Use the Select-Fields below to filter the programme.
Opening & Plenary Lecture
K1 - Keynote Lecture I
F1 - Filter Media Quality Control / Pore Size Analysis I
G1 - Surface Filtration
L1 - Fractionation of Fine Particles in Liquids
K2 - Keynote Lecture II
F2 - Filter Media Quality Control / Pore Size Analysis II
G2 - Respiratory Masks I
L2 - Filter Presses I
F3 - Progress in Filter Media Manufacturing
G3 - Respiratory Masks II
G4 - Particle-Collector-Interaction
L3 - Integrated Processes – Crystallization / Separation / Drying
L4 - Filter Presses II
F4 - Filter Media Development I
F5 - Filter Media Development II
G5 - Industrial Air and Gas Cleaning
L5 - Press Filtration – Pressing / Shearing / Electro-Assistance
M1 - Waste Water Treatment
K3 - Keynote Lecture III
F6 - Filter Media Development III
L6 - Filter Cake Washing
M2 - Ultrafiltration
K4 - Keynote Lecture IV
F7 - Filter Media Development IV
G6 - Automotive Applications
L7 - Backwashing Filtration
F8 - Poster Session
G7 - Poster Session I
G8 - Poster Session II
L8 - Modelling Centrifugal Filtration + Sedimentation
L9 - Poster Session II
F9 - Surface Finishing of Filter Media
G9 - Filter Test Systems
L10 - Modelling Pressure Cake Filtration
L11 - Depth Filtration – Adsorption
M3 - Ultra- and Nanofiltration
G10 - Modelling and Simulation I
G11 - Air Filtration I
L12 - Modelling Decanter Centrifuges
M4 - Modelling and Simulation
M5 - New Processes
G12 - Modelling and Simulation II
G13 - Air Filtration II
L13 - Flotation-Adsorption-Coalescence / Surface Effects
L14 - Metrological Analysis of Data for Particle/Liquid-Separation
M6 - Water Production
G14 - Mist and Droplet Separation I
G15 - Air Filtration III
L15 - Flocculation / Filter Aids
L16 - Characterization and Modelling and Pore Structures
M7 - New Membranes I
G16 - Mist and Droplet Separation II
G17 - Air Filtration IV
L17 - Innovative Separation Processes
L18 - Optimization of Cake Filtration by Physico-Chemistry
M8 - New Membranes II
Day: 08 March 2022
Time: 10:15 - 12:00 h
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Roaring twenties in air filtration - driving for a cleaner world
Dr. Martin Lehmann*, MANN+HUMMEL GmbH, Germany
In medias res: Air filtration is omnipresent for delivering clean air: protecting engine and equipment known as engine filtration, enabling processes and technology known as industrial filtration, providing comfort and indoor air quality known as HVAC filtration. Adding gas adsorption, the domain of cabin air filtration shows up. However, in this talk the focus will be on particle filtration.
Tempora mutantur et nos mutamur in illis. A bit more than twenty years ago, the digital revolution in air filtration started. First realistic simulations of particle collection on single fibers. First time visualization of the 3D microstructure of a fibrous filter. CFD and FEA have become a key tool for designing air intake systems. Nowadays, we are starting to use AI-based simulation tools for designing air filter elements. In addition, in the past twenty years the design of the filter elements changed significantly. There is no longer a set of just rectangular or round filter elements. With evolving production technology, we are now thinking and designing in flexible design shapes with concave curvature, oval shape or variable pleat heights. Customers have become used to filter elements fitting just right into their complex 3D design space.
Quo vadis air filtration? Our decade of the 2020s is a quite prosperous time for air filtration. The production of new internal combustion cars is still growing (until the end of 2020s), the vehicle in operations will further grow, and filtration for heavy duty and industrial equipment will continue to be in demand. But it is also a time to redefine air filtration: New air filtration products will be needed, even for e-mobility. Focusing on reducing emissions adds the need for innovative filtration solutions, such as brake dust filtration, but also demands some kind of an altruistic, community-centered approach: With my frond-end air filter, I contribute to lower fine dust emissions while driving!
The plenary lecture will be a personal collection of examples illustrating the evolution of air filtration in the approximately last twenty years as well as an outlook into the roaring 2020s in air filtration....
12:00h - Lunch
Day: 08 March 2022
Time: 13:00 - 14:15 h
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Membrane science and functional materials
Prof. Dr. Liang-Yin Chu, Sichuan University, China
Functional membranes are playing paramount roles for sustainable development in myriad aspects such as energy, environments, resources and human health. However, the unalterable pore size and surface property of traditional porous membranes restrict their efficient applications. The performances of traditional functional membranes will be weakened upon the unavoidable membrane fouling, and they cannot be applied to the cases where self-regulated permeability and selectivity are required. Inspired by the natural cell membranes with stimuli-responsive channels, artificial stimuli-responsive smart functional membranes are developed by chemically/physically incorporating stimuli-responsive materials as functional gates into traditional porous functional membranes to provide advanced functions and enhanced performances for breaking the bottlenecks of traditional membrane technology. The smart functional membranes, integrating the advantages of traditional porous membrane substrates and smart functional gates, can self-regulate their permeability and selectivity via flexible adjustment of pore sizes and surface properties based on the “open/close” switch of the smart gates in response to environmental stimuli.[1-4] This presentation will introduce the recent development of stimuli-responsive smart functional membranes, including the design strategies and the fabrication strategies that based on introduction of the stimuli-responsive gates after or during membrane formation, the responsive models of versatile stimuli-responsive smart functional membranes, as well as the advanced applications of smart functional membranes for separating chemical/biological substances based on size or affinity, regulating substance concentration in reactors, and controlling release rate of drugs. With the self-regulated membrane performances, smart functional membranes show great power for global sustainable development...
Nonwovens for hygiene and medical applications: Optical quality control can manage the increasing requirements for functional membranes
M. Klein*, Dr. Schenk GmbH, Germany
Triggered by the intensive need for medical respirators, surgical masks and face masks (personal protective equipment) since the beginning of 2020, the production of high-end filter material was increased dramatically. However, not only the volume was boosted, but also the requirements on the quality of the mask material were tightened to fight the Covid 19 pandemic.
Defects in functional membranes, e.g. for medical respirators, may result in more airborne particles, e.g. droplets containing bacteria and viruses, passing through. The number of particles passing through is one of the main factors determining the protection class of a medical respirator:
Harmful dusts, smoke, aerosols and infectious agents.
Toxic and harmful dusts, smoke, aerosols and infectious agents.
Filtration of particles
As high filtration rates are essential according to the requirements given above, meltblown material is the favorite for MPE and PPE applications. However, local defects (such as micro-holes, dirt, drops and many more) can impair the function of the filter medium. Detecting these problems inline during production of the base material is a safeguard against delivery of defective products. Inline optical inspection in the subsequent converting process will provide the required attention and care to quality aspects.
In parallel, monitoring of more general material properties is necessary. Optical quality control systems can also help..
Air filter testing using bacteriophages as virus surrogate
B. Führer*, H. Elsayed, C. Hartl, M. Kaiser, G. Ettenberger, OFI Technology & Innovation Ltd, Austria; U. Häfner, Freudenberg Filtration Technologies SE & Co. KG, Germany
Infectious particles such as viruses or bacteria are ubiquitous and most occurring transmission is from human to human. Virus-laden particles originating from the respiratory tract produced during sneezing or coughing is typically 5 µm or less in diameter. Particles that are smaller than 5 µm can remain airborne for hours and can be inhaled by a person. Indoor air filters or face masks can play a significant role within reduction or inactivation of infectious particles in respiratory aerosols, especially during pandemics such as COVID-19. Currently, air filters are mostly tested with well-defined mineral particles or plasticizer aerosols such as ISO 12103-1 A2 fine dust or DEHS. These standardized test dusts represent the particle size of bioaerosols, but are often not representative for the physicochemical properties of bioaerosols.
As biological particles such as viruses have a different behaviour and show detectable infectious potential compared to non-biological particles it is important for filter design and testing to investigate the interactions between bioaerosols and (biofunctional) filters. The aim was to develop a standardized method for testing filter media and modules with defined bioaerosol containing MS2 bacteriophages, serving as virus surrogate, via a special designed filter test rig. The focus lay on comparison of biological separation efficiency with the separation efficiency of common non-biological aerosols as it is important to know about the biological risk of the particles exposed to the filter and to humans and not only number and size.
A method to test filter media and whole filter modules directly with bioaerosols was developed on a filter test rig. Test aerosol consisting of a defined amount of MS2 bacteriophages was applied in order to determine viral filtration efficiency of filters. A stable method was established for different air flow rates depending on the field of application. Results demonstrate that...
Efficient filter media and membrane testing (cut-off) by number-based size distribution of nano- and microparticles (SPLS-Technology®)
E. Wollik, H. Woehlecke, H. Lichtenfeld, Dr. Lerche KG; M. Hussels, Physikalisch-Technische Bundesanstalt (PTB); D. Lerche*, LUM GmbH, Germany
Many products of daily life and industrial use are based on suspension and emulsions. Monitoring of product compositions is essential for the control of unit processes. Nowadays, it is given a clear preference of in-line solutions. Changes in product quality have to be detected continuously and quickly to adjust the production process.
Measurements based on optical methods are used widespread. Optical response is fast, do not need to measure direct inside the sample and work without any chemicals and sampling.
This contribution introduces an optical method for in-situ measurement of suspensions and emulsions based on reflectance. The so called Multi reflectance spectroscopy (MRS) technology is an innovative technique based on multiwavelength reflectometry and capable of predict dispersion quality parameter such as suspended solid concentration or particle size...
Identification of particle emission hotspots in baghouse filters via spatially resolved pm measurement
P. Bächler*, J. Meyer, A. Dittler, Karlsruhe Institute of Technology (KIT), Germany
Baghouse filters are used in a variety of gas cleaning applications in order to lower dust emissions and protect the environment. State of the art filter media generally enable low particle emission levels, where a particle emission peak occurs for a short duration after filter regeneration due to penetration of particles through the filter medium. After sufficient cake formation, the emission drops to a zero level in the case of ideal, leak free operation. Leaks of the filter bag, damaged media surfaces or other defects can significantly increase the overall particle emission of the baghouse. The emission contribution of these “hotspots” may easily exceed the emission contribution of all other filter elements. Triboelectrical sensors can be installed on the clean gas side for the measurement of the total emission and alarm plant operators about an increase in particle emission, however these sensors do not offer spatial resolution and information about the location of the emission hotspot. In many applications fluorescent dust is used to determine the location of leaks and defects, however the localization of the leak itself requires a shutdown of the filter house. A potential technology for spatially resolved online measurement of particle emissions are low-cost PM-sensors due to their compact size and low investment cost. In this study, each of a total of nine filter bags of a small scale baghouse filter has been equipped with a low-cost PM-sensor of the model OPC-N3 from the manufacturer Alphasense...
Penetration of soluble material through surface filters due to exposure to water mist
- impact of the filter material wettability
A. Schwarz*, J. Meyer, A. Dittler, Karlsruhe Institute of Technology (KIT), Germany
The presence of water droplets in gas cleaning filtration systems due to fog, spray rain or condensation has an impact on the filters’ operating performance. The differential pressure between the raw and the clean gas side of the filter is a key parameter considering the energy efficiency of the filter.
The exposure of an established filter cake with soluble components on the filter surface to water mist leads to structural changes of the deposited particle collective. Dendrite structures collapse and particles rearrange on the filter surface. Soluble particles dissolve. The solution may penetrate through the filter medium to the clean gas side depending on the composition of the cake (e.g. ratio of soluble salt particles and insoluble dust) and the operation parameters (mainly duration of liquid exposure).
The presented work focuses on the penetration of soluble material through surface filters due to contact with water mist and the resulting change in the differential pressure, depending on the wettability of the filter (hydrophilic or hydrophobic filter medium)...
High resolution permeability study of used non-woven filtration media from a u.k. energy from waste combustion site
D. Curry*, W. Nimmo, University of Sheffield; J. Howarth, B. Dannatt, Durham Filtration, UK
Assessment methods such as permeability, mass, and thickness are often utilized to characterize used nonwoven filtration media. Nonwoven filtration media commonly displays some degree of variation from the fabrication process, which can be exacerbated in the used filtration media. Current standard testing methods assess filtration media in three localised regions: this study shows that there is a considerable permeability variation across the vertical and axial length of the media which warrants consideration during analysis.
This novel, high resolution permeability, study illustrates the variation between pre and post pulse jet cleaning using an industrial derived sample. The test method illustrates the limitations of current industrial test methods...
Continuous fractionation of fine particles using crossflow
P. Lösch*, S. Paas, K. Nikolaus, S. Antonyuk,
Institute of Particle Process Engineering, Technische Universität Kaiserslautern, Germany
The increasing demand of fine particles in suspensions requires new processes which can provide such dispersed particle collectives. These suspensions are for example intermediates for the production of coatings, structured reinforced plastic or for printed electronics. While production processes like precipitation or crystallization are often generating particles with broad particle size distributions, a succeeding process step of classification is necessary. In known separation processes, such as sedimentation, filtration or centrifugation, the particles are either classified according to a certain grain size or sorted by a physical characteristic. However, in many applications in which finely dispersed multicomponent mixtures of particles with sizes < 10 μm with different properties are to be separated in industrially relevant quantities, the usage of a single separating feature is often no longer sufficient.
In this contribution, a novel cross-sectional fractionation technique is being presented, which is a promising method for the highly specific separation of micro- and sub-micron suspensions...
Automatic fractionation of particles from lithium-ion batteries in a tubular centrifuge with model-based control
T. Sinn*, M. Gleiß, H. Nirschl, Karlsruhe Institute of Technology (KIT), Germany
The process industry is currently undergoing various changes at the moment. For economic and ecological reasons, resource-efficiency is more and more requested, meaning the optimal exploitation of energy and materials through by optimal operation of existing production plants. However, when processes are too complex, conventional practices are often not able to operate the process satisfactorily close to the optimum. The same challenge arises when specific product properties are demanded, but the process changes its behavior during operation. Accurate setting of operational parameters is required, which must be realized through a sensible control strategy. In such complex cases, a model-based control is a potentially sound solution.
At the same time, mobility is about to undergo a fundamental transformation towards electric vehicles. This will certainly entail a growing demand for materials needed in batteries (Li, Mn, Co for example) as well as increase the urgency to develop recycling processes for end-of-life batteries.
This work treats the investigation of centrifugation as a potential step in a battery recycling chain. The well-known unit operation is examined as the key step – separation of battery constituents for further selective treatment – in a newly developed direct recycling approach for Li-ion battery cathodes. The partially nano-sized particulate cathode material enters a tubular centrifuge to fractionate the constituents. In order to assure the separation of only one species from the watery suspension, the operational parameters must be carefully set. Due to the progressive sediment build-up inside the rotor, the separation conditions in tubular centrifuges change accordingly. If this is not counteracted, centrate properties are time-dependent and the desired fractionation output is not attained. To achieve complete fractionation over the entire operation time, continuous control of the operating parameters, that are rotational speed and volumetric flow rate, is realized in form of...
Modeling of shape and density fractionation in tubular centrifuges
M. Winkler*, H. Nirschl, Karlsruhe Institute of Technology (KIT), Germany
Classification is an established process in solids processing technology to divide particulate products into defined fractions based on their size. However, complex particle systems with strict specifications regarding product-relevant properties often require a different approach. Thus, multi-dimensional fractionation is needed in which both geometric (particle size and shape) and material (density, interfacial properties) separation characteristics are considered. If a task involves the efficient separation of nanoparticles based on their shape, size or solid density, high centrifugal forces are required. Due to their advantageous throughput rates and extreme operating conditions, tubular centrifuges are well suited for this application.
During separation, a low concentrated suspension is fed into the tube centrifuge rotor with a constant volumetric flow rate. Suspended nanoparticles settle along the radial and axial coordinates inside a fluid reservoir. Their sedimentation velocity is determined by their geometric and chemical properties and the operating conditions of the apparatus. Fractions with sufficiently low settling rates are transported beyond the rotor weir and enter the fine product stream. The removed solids accumulate along the separation zone on the inner rotor wall. To gain process knowledge and estimate the separation result for a well characterized product, dynamic process simulation is an effective tool. Previous studies focused on the one-dimensional classification of fines, whereby only one separation characteristic, the particle size, and its distribution, was considered in the calculation. This work strives to further extend well established one-dimensional model equations by an additional separation criterion, i.e. the shape or aspect ratio of individual particles. The numerical calculation of the particle transport behavior in tubular centrifuges shall thus be given a broader range of applications and help to identify advantageous operating parameters and apparatus specifications.
This study includes the generation of multi-dimensional density distributions that define a property range of non-spherical particles as a function of at least two geometric features...
14:15h - Coffee Break
Day: 08 March 2022
Time: 14:45 - 16:00 h
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The role of structural and surface properties of depth filter media designed for selected separation processes
Prof. Dr.-Ing. Andrzej Krasinski, Warsaw University, Poland
The presentation covers examples on the enhancement of filtration performance by modification of fibrous media tailored for specific processes. The topic will include an optimization of depth filter for solid filtration and coalescence (both gas-liquid and liquid-liquid), methods for modification of filter structure by deposition or synthesis of particles on the fibers to obtain expected wettability as well as fabrication and testing of antibacterial filters. The latter application will be addressed for filtration of water biofuels, where the formation of biofilm can lead to a rapid clogging of filter due to bacteria growth and bacteria reemission to the outlet. Other prospective features like photocatalytic effects of the composite filters for organics decomposition will also be presented...
Assessing cloudiness in non-wovens
M. Godehardt, A. Moghiseh, C. Oetjen, K. Schladitz*, Fraunhofer Institute for Industrial Mathematics (ITWM); J. Ohser, University of Applied Science Darmstadt; S. Ringger, I. Windschiegel, Institute for Textile Technology and Process Engineering Denkendorf (ITV), Germany
The homogeneity of filter media is important for material selection and quality control, along with the specific weight (nominal grammage) and the distribution of the local weight. Cloudiness or formation is a concept used to describe deviations from homogeneity in filter media. There are various image analysis methods for measuring cloudiness differing in the exact definition of this term. Cloudiness concepts based on the range of interaction, the coefficients of the Laplace pyramid, or the power spectrum have been suggested. Measured cloudiness is reproducible. However, cloudiness measured with varying instruments usually cannot be compared. We have developed a theoretically sound cloudiness index and a method to measure it from the power spectrum. The eligible frequency band depends on the image acquisition. Reproducibility of the method is guaranteed as long as the non-woven sample attenuates the light proportional to the material thickness. Our method is hence well suited to build a technical standard on it.
Following, we suggest to derive the cloudiness index from the power spectrum of the relative local area weight, averaged over a selected frequency range. Here, relative local area weight means local area weight divided by specific weight. This cloudiness measure has various advantages over popular alternatives, both in terms of the information contained and the robustness of the measurement . The power spectrum captures the energy density in a broad spectral range. Moreover, under certain conditions, the structure of a nonwoven is fully characterized by the specific weight, the variance of the local weight, and the power spectrum. Consequently, the power spectrum is the parameter that exclusively reflects the cloudiness.
Here, we address questions arising from practical application. The most prominent is the choice of the spectral band to properly capture a non-woven’s cloudiness relevant for the physical properties as well as meeting visual perception. The band...
Determination of the first bubble point by capillary flow porometry
D. Dutczak*, K. Chojnacka-Gorka, I. Struzynska-Piron, POROMETER NV; E. Pattyn, D. Pattyn, APTCO Technologies, Belgium; K. van der Kamp, IB-FT GmbH, Germany
The largest pore size often called the first bubble point (FBP) is one of the most critical properties of a porous material. It determines the barrier properties of the membrane and affects the flux of permeating species across the membrane. The first bubble point test is used to confirm the pore-size rating, which is among others the key selection criterion for membrane filters. This is especially important in water filtration applications and in the pharmaceutical and medical industries as it indicates the extent of particle size that can effectively be retained.
The ASTM F-316-03 defines the first bubble point at the pressure at which the first continuous gas bubbles are detected. The “bubble point” method as described in ASTM F-316 is based on a visual determination, and thus it is influenced by the subjectivity and precision of the operator.
In this work, we present the determination of the largest pore size in different filtration media by using an automated first bubble point tester POROLUX™50 and a capillary flow porometer POROLUX™1000...
Membrane characterization by analytical multisample photo-centrifugal filtration (ACF)
P. Lösch*, C. Weibel, S. Antonyuk, Technische Universität Kaiserslautern, S. Boldt, D. Krause, D. Lerche, LUM GmbH, Germany
The continuous development of new products in pharma and biotechnology leads to a need of required processes for further processing. Especially proteins or vaccines, which are obtained from cell suspensions, require separation processes for further processing. To achieve the best filterability for a special application, the membranes, woven or nonwoven filter materials with tailor-made structure have to be developed For the design and dimensioning of filtration processes, standardized laboratory tests are usually performed [1,2]. To cover a wide range of processes, the standardized tests require a quite large filtration area and a large amount of the suspension to be filtered. For cost reduction in both the use of valuable pharmaceutical products and newly developed membranes, it is advisable to reduce the required material input. A new possibility is to perform the filtration experiments by means of analytical photo-centrifugation filtration (ACF) which allows a simple and fast membrane characterization and filterability with high throughput [3,4]. With ACF it is possible to analyze up to 12 different...
Investigation of the near-field and far-field protection effect of face masks using micro-scale and macro-scale CFD simulations
A. Baumann*, D. Hoch, J. Niessner, Heilbronn University of Applied Sciences, Germany
Due to the Corona pandemic, the wearing of masks is mandatory in many fields of life. Inhaling and exhaling while wearing a mask can be stressful over a long period of time, especially during strenuous exertions - even for healthy persons. Providing masks with a low pressure drop at a high filtration efficiency is crucial for persons with preexisting trouble breathing who are especially vulnerable. Therefore, the aim of this work is to investigate both the near-field and the far-field protection effect of existing medical and FFP2 masks and of a proposed optimized mask with.
The set-up of the CFD model is carried out in 4 stages corresponding to 4 spatial scales. In the first stage, based on µCT scans, individual fibers of mask materials are resolved and pressure loss, filtration efficiency and macro-scale material parameters are determined by micro-scale simulation. In stage two, these macro-scale parameters are used in macro-simulations on flat sheet samples of face masks to determine the pressure loss of the entire mask material and compare them to the results obtained in stage 1. Stage 3 focusses on the near field of a mask and takes the different mask shapes into account. The simulations serve for determining pressure loss of the complete mask including the effect of the shape of the mask. Last but not least, in stage four, the exhalation of aerosols through a mask is investigated in order to determine the far-field reduction of aerosol concentration by the mask. For this purpose, the flow field corresponding to different aerosol generation processes such as breathing, talking and coughing is simulated using a Eulerian approach and a specific particle distribution for every case is injected after the steady-state flow solution has occurred (Lagrangian approach).
Simulation results of pressure drop and filtration efficiency of medical, FFP2, and optimized masks are shown and validated by comparison to experimental data. We investigate the influence of the shape of the mask, the leakage due to a bad fit of the mask as well as the effect of different aerosol injection scenarios (breathing, coughing, talking) on the reduction of the far-field aerosol particle concentration allowing to assess the protection effect of the different types of masks.
Modeling and simulation of moisture penetration and wearing time of face masks
M. Böhle, R. Kirsch, S. Osterroth, Technische Universität Kaiserslautern; A. Schwarzwälder*, Karlsruhe Institute of Technology (KIT), Germany
The last two years has shown an increasing awareness of the use of face masks and respirators in order to protect the wearer or the surrounding people against infections.
Two protection concepts can be distinguished: self-protection and external protection. In the first concept, the wearer wants to protect himself or herself against infectious pathogens or viruses in the surrounding. Depending on the availability, corresponding filter masks should be preferably used by people working in health and nursing care. In the second concept, the wearer protects people in the surrounding from being infected.
A reliable protection does not only depend on the filtration properties of the mask material. In the literature, it is discussed whether moisture penetration decreases the filtering efficiency. If this is the case, the safety is reduced. The most critical state is reached when the mask is imbrued entirely (moisture breakthrough) since the moisture can serve as an "infection bridge" spanning across the depth of the filter material. This holds for highly efficient filter masks (e.g. FFP-2), but even more so for masks to protect others: Coughing and sneezing can lead to the detachment of potentially infectious droplets from the outer surface, which will then spread into the vicinity. In standard test procedures such as DIN EN 14683, DIN EN 149, or 42 CFR Part 84, the temperature and the moisture content are considered as constant and static. The test material is adjusted to given conditions. However, when breathing out, the face mask is exposed to moisture and the temperature (body heat) is different from the surrounding.
Most wearing time recommendations are reference values, based on an average usage scenario. The speed and intensity of the moisture penetration of a mask depend heavily on the physical stress level of the wearing person. The time it takes until the moisture breaks through cannot be derived in a simple way ("rule of thumb") from the physical activity, which is usually fluctuating. In general, a visual check of the mask is neither feasible without aid nor reliable enough to detect a moisture breakthrough.
Specialized computer simulation tools have proven to be very useful for the innovation and optimization of filtration devices. Previous studies were mostly focused on filtration efficiency and have not considered the moisture transport. Additionally, the breathing behavior was modeled using an idealized sinusoidal profile.
The present work is devoted to the adaptation of well-known transport models to the transport of moisture in porous media...
Evaluation of various face covering filter materials using particles classified by aerodynamic diameter up to 5 µm
S. Payne, J. Symonds, Cambustion Ltd., UK
During the COVID-19 pandemic, face coverings have been widely worn in public spaces to capture respiratory particles produced by the wearer and reduce spread of infection. These commonly consist of layers of woven fabric. Surgical masks are intended for health care staff to protect patients during surgical procedures and in other medical settings. Respiratory filtering half masks are intended to protect the wearer and are regulated as personal protective equipment (PPE) for inhaled air only.
Numerous recent studies have emphasised the possibility of airborne coronavirus transmission. While the World Health Organisation (WHO) defines droplets as ≥5-10 μm diameter and aerosols as <5 μm, both can be generated as a continuum of particle sizes during various respiratory activities including coughing, talking and singing.
In this study the filtration properties of various face mask materials were investigated across a broad range of particle sizes. The interception mechanism is important for large particle capture, for which aerodynamic diameter is the most useful measure of size. A suitable instrument for achieving this is the Aerodynamic Aerosol Classifier (AAC), which can select particle sizes between 25 nm and >5 μm by using a rotating cylinder to balance opposing centrifugal and drag forces for the desired aerodynamic diameter, so that particles move across a sheath flow to the outlet. This principle of aerosol selection is independent of the charge state and produces a truly monodisperse aerosol with a high transmission efficiency limited only by diffusion and impaction losses.
This study uses an AAC to select monodisperse test particles by aerodynamic diameter in order to assess the filtration performance of various face covering materials, in both flow directions and at filter face velocities representative of inhalation and exhalation flow rates...
Setting the grounds for a dynamic adjustment of the operational parameters of a press filter using ai to compensate for slurry quality changes
J. Bruzzo*, J. Koskela, S. Manninen, K. Kettunen, Flowrox Oy, Finland
The step of solid/liquid separation (pressure filtration for the case of this study) is usually one of the last steps in the chain of raw material transformation in concentration plants adding tremendous value to the product being handled. As in every production process, it is expected that the resulting products (cake) comply with a series of prescribed conditions in terms of planned production, operational expenses (resource consumption), and quality. Sound world-class asset management of the solid/liquid separation equipment is key to meet these operative requirements and might well be the difference between reaching budgeted profits or wasting company money continuously.
Nonetheless, not even the most rigorous world-class asset management structure can completely foresee the level of impact that deviated process variations in equipment upstream can have on the filtration step. Nor the reactive measures taken by the filtration team can guarantee to compensate for these process deviations in time to keep production, consumables, and quality in the budgeted levels.
Filtration units such as pressure filters are provided with rigid settings, a fixed set of stages to be followed or physical conditions to be met during each filtration cycle regardless of the quality of the slurry being fed to the filter. This rigidity makes continued reactive adjustments an untenable endeavor. Constant supervision is needed to manually change these filtration settings to accommodate to slurry conditions to get the best possible output from the filter. Unfortunately, this task is labor-intensive, and having constant supervision plays against the limited organizational structure in place. Many cycles can be run before a suitable action is taken in the filtration settings or ideally before the deviation is corrected in the upstream process. There seems to still prevail an independency of pipelined processes, where changes in key variables are not automatically communicated to the rest of the actors across the production chain introducing thus negative consequences.
This paper aims to set the grounds for migrating from a manual and close-to-obsolete filter supervision to a novel automatized adaptive supervision-free response philosophy...
Artificial intelligence (AI) for filter presses to predict filter cloth change and dry substance
A. Decker*, ANDRITZ Separation GmbH, Germany
In all industries, efficient filtration is a key process step in achieving high product quality. One of the most common products used for filtration is the filter press, which has gone through a lot of changes over the decades. Among the latest innovations in filter press development is the use of artificial intelligence (AI) on mobile devices.
One of the challenges for filter press operators is estimating when the best time will be, from an economic perspective, to clean the machine or even change the filter cloths in order to avoid any damage to the filter press and achieve filter press efficiency at the most constant level possible.
By collecting process parameters and making use of AI, ANDRITZ has found a way of providing its customers with a tool that can tell the customer in advance, on the basis of the data collected, when the filter press will need to be cleaned and the filter cloths will have to be changed.
The AI records the filter press process data and then says when the filter cloths should be changed as well as predicting the dry substance in the suspension based on the data gathered.
By using process parameters such as pressure, temperature and feed, the AI is able to say what the dry substance will be and when the optimum time is to terminate the cycle, thus saving time and energy as well as avoiding unnecessary mechanical strain on the plates and cloths.
These programs are a part of the ANDRITZ Intelligent Filter Press, and they are explained in this paper by means of examples...
Optimization of the dewatering process for concentrate pressure filtering by support vector regression
H. Liu, K. You*, Jiangxi University of Science and Technology, China
In order to better improve the efficiency of the concentrate filter press dehydration operation, this paper studies the mechanism and optimization methods of the filter press dehydration process. Machine learning models of RBF-OLS, RBF-GRNN and support vector regression (SVR) are constructed respectively, and Perform laboratory simulation and industrial simulation separately. SVR achieves the best accuracy in industrial simulation, the simulated mean relative error (MRE) of moisture and processing capacity are respectively 1.57% and 3.81%. Finally, a simulation model of the filter press dehydration process established by SVR, and the optimtical simulation results Obtained by optimization method based on control variables. The results show that...
Day: 08 March 2022
Time: 16:45 - 18:00 h
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Foaming adhesives – More joy or pain for industrial filtration?
F. Steegmanns*, Stockmeier Urethanes GmbH & Co.KG, Germany
In the industrial filtration industry, compact adhesives and potting systems been used for several years for the production of cartridges and filter elements. Here we will only consider the application of polyurethane systems. Obvious, the advantage for this is no other material offers such a comparable performance spectrum. From very soft to high-strength, as compact material or foam, with very good temperature and/or chemical resistance and a broad adhesion spectrum on a wide variety of substrates, almost all requirements can be met in the formulation of polyurethane.
When companies forced with the decision to reduce costs, they first have the possibility to change the material or the supplier. This brings smaller savings, but can also lead to disadvantages in quality and/or other disadvantages. The laws of business also apply here: Good chemistry costs money!
With the used adhesive and potting systems, a gap between the filter paper and the frame or end caps is usually filled and the filter stabilized. What could be more obvious than the idea of foaming exactly this system and thus quickly saving half or more of the adhesive and potting system used. In addition, you gain another decisive advantage: The weight of the filters is reduced by the amount of material saved also. So much for the theory.
The otherwise standardized and good-natured adhesive and potting systems used as a compact material cannot be replaced just so easily by foaming systems. Nearly every application needs to be considered in a separate project and requires a more or less individual solution as our many years of experience show us.
Advantages and disadvantages have to be weighed up against each other and the possible additional investments have to be compared with the expected savings. In lots cases the development of a new filter generation, including frames or endcaps, is necessary because the previous design does not allow the use of foaming products so easily.
A common, comprehensive and close cooperation is necessary in such a project from the very beginning.
Laser precision drilling for future applications against viral diseases
T. Barthels*, M. Reininghaus, Fraunhofer Institute for Laser Technology ILT, Germany
In the field of micro and nano laser structuring, ultrashort pulse (USP) laser material processing is attracting increasing attention due to its ability to generate precise hole pattern with high throughput and quality requirements. The multibeamscanner (MBS) enables laser processing with strong parallelization of more than 200 beams in order to achieve even higher throughputs while maintaining the same drilling quality.
The aim is transferring latest research results and years of process development for laser-based multibeam machining of tool inserts in consumer electronics to new and technologically demanding markets such as the filter industry. On the basis of the existing process knowledge the process of effectively drilling holes with micro- and sub-micrometer diameters is content of further investigations. The use of USP lasers offer the potential to produce filters made of stainless steel foil with < 1 µm sized holes. The MBS production technology is suitable for manufacturing micro and nano filters for industrial applications in the fields of biotechnology, pharmacy and medical technology. The use of the manufactured filters is also conceivable for special applications such as an atomizer module in inhalation devices for a targeted dosing of antiviral medication. Latest USP laser machines...
Sustainable weaving: Modular weaving machine concepts for the production of high-performance filter fabrics
L. Öller*, Lindauer DORNIER GmbH, Germany
The modern weaver faces many challenges: Digitisation is weaving its way deep into the production chain, sustainability requirements are increasing, and there is a shortage of young people and skilled workers. Flexibility in production is increasingly becoming an existential question. DORNIER's weaving machine system family offers answers to this – in the form of the very latest weaving machines and weaving solutions.
Under the motto "The Green Machine", the family-owned company from Lake Constance, which manufactures its machines exclusively in Germany, presents comprehensive solutions for sustainable technologies.
With this guiding principle DORNIER is not just hinting at the well-known green varnish of the weaving machines but, above all, at the "green effect" of the fabrics they produce.
These fabrics are of crucial importance for many "green technologies" in almost all industrial sectors. Whether finest filters for cleaning water or air, fabrics as carriers for catalysts or exhausts, in all these sectors DORNIER "Green Machines" are indispensable for the production of precision fabrics. Especially in these areas, where the highest demands are placed on the fabric, DORNIER weaving machines unfold their unique performance. This results from the quality of production, the imagination of the developers and engineers and the consequent exchange of ideas with customers.
Even more flexible, faster and more efficient: This is what the P2 rapier weaving machine in three versions stands for. In addition to the standard version, the P2V is also supplied as a reinforced version with a reed impact force of up to 37 kN and the P2S heavy fabric weaving machine with a maximum reed impact force of 50 kN for particularly heavy and dense technical fabrics. Like all DORNIER weaving machines, the P2 in all versions features the unrivalled DORNIER SyncroDrive® drive concept and the powerful interface for easy integration into the IT and tool environments of the weaving mills.
Further developments of the machines are always carried out under sustainability aspects and the company motto "Quality creates value". The DisCoS® (DCS) colour selector and feed system, which allows up to 16 colours to be processed particularly easily, and the DoPPIO® double-weft rapier heads with free colour feed and parallel weft insertion provide an additional increase in productivity.
Machines and plants with a service life of several decades, and worldwide support even for “green machines” that have been in production for over 30 years are not uncommon. With trained technicians working close to the customer, we guarantee a worldwide mechanical, electronic and weaving technological service...
Filtration performance of certified face masks with respect to usage in the covid-19 pandemic context
S. Berger*, M. Mattern, J. Niessner, Heilbronn University of Applied Sciences, Germany
During the COVID-19 pandemic, certified respiratory masks emerged as a key protective measure against direct and indirect infections from virus-laden aerosols. However, their standardised test procedures lack relevant aspects to evaluate the filtration performance with respect to respiratory aerosol particles. The presented work deals with two of these under-represented factors, namely the filtration efficiency depending on the nature and size of exhaled aerosol particles and the filtration performance associated with facial leakage considering a differentiated distinction between self-protection and third-party protection. Therefore, the fractional efficiency and the net pressure loss are experimentally determined within a screening of different medical masks (EN 14683) and filtering face pieces (FFP2, FFP3) (EN 149).
While the certification of medical masks and filtering face pieces either uses bacteria-laden aerosol particle distributions with a mean diameter of 3 µm (EN 14683) or liquid paraffin oil droplets and solid-phase sodium chloride particles (EN 149), that neither represent the species nor the size of exhaled droplet nuclei, we use aerosol particles from artificial saliva. A comparison of both artificial and actually exhaled aerosol particles shows that...
PALAS - Quick and reliable test of community masks with regard to the new EN Guideline CWA 17553
S. Schütz*, M. Schmidt, PALAS GmbH, Germany
Community mask are the most common national strategies to in Europe to lift legal relationships caused by covid pandemic. Uniform security standards across Europe can be part of this, to contain the COVID-19 pandemic across borders. The CWA assist producer who switched their production to non-medical mask, the so-called community masks.Therefore, an upcoming new EU directive CWA 17553 will be released by CWA with the title “Community face coverings – Guide to minimum requirements, methods of testing and use”.
Even before that Palas already started a development of a fast, economical and easy to handle measurement device the Mas-Q-Check. The Mas-Q-Check was developed by Palas to subject protective masks to a quick, simple and yet meaningful test before use. A particle counting measurement device is used, which is able to detect efficiencies in the size range of viruses and bacteria. The system can also be used for training purposes as it immediately shows the efficiency of protective masks.
The mask is placed on the test head before use. Using a high-resolution aerosol spectrometer, the particle contamination (size and quantity) in the ambient air is measured. Afterwards the device switches automatically and determines the value of the particle contamination behind the protective mask. This can be repeated automatically several times.
How face masks help stop COVID-19
K.-J. Choi*, Clean & Science Co., Ltd., USA
The Centers for Disease Control and Prevention (CDC) continues to recommend that persons in the U.S. wear masks in public settings “around people who don’t live in your household and when you can’t stay 6 feet away from others.” Masks help stop the spread of COVID-19. In many states there is a legal requirement to wear masks in public buildings and spaces. This presentation will cover the nature of COVID-19 virus particles, the current test methods of facemask filtration, and the test results comparing N-95 mask, surgical mask, and cloth mask.
Detachment and transport of reactive-inert agglomerates at different flow velocities in a gas cleaning model filter channel
J. R. D. Thieringer*, J. Meyer, A. Dittler, Karlsruhe Institute of Technology (KIT), Germany
Particulate filters are a standard component in exhaust aftertreatment systems of trucks and cars to remove reactive (soot) and inert (ash) particles from the exhaust gas. The particulate filters consist of parallel channels with alternately blocked ends. Particles are deposited in the inlet channel, while the gas flows through the porous filter wall into the outlet channel. After reaching a defined pressure drop to clean the filter from the reactive components, the filter is regenerated. During the regeneration, the soot particles are oxidized and the particle layer breaks up. Agglomerates can be detached, transported along the filter channel and deposited at the end plug of the inlet channel.
Nevertheless, the influence of the particle properties on the resulting deposition pat-terns and the rearrangement of agglomerates in the particulate filters remain unclear.
In this study, the rearrangement (detachment, transport and deposition) of agglomerates without regeneration of the reactive particles in the filter is investigated in order to observe the fundamental processes of detachment and transport of agglomerates in cross-flow filters...
Influence of structure morphology on detachment behavior of deposited agglomerates from a stretchable single fiber during multiple fiber elongations
L. Poggemann*, J. Meyer, A. Dittler, Karlsruhe Institute of Technology (KIT), Germany
Depth filters are commonly used for particulate matter removal in several fields of application like air-conditioning, cleanroom technology and cabin air filters. Two main parameters are of interest for the characterization of the operating behavior: separation efficiency and pressure drop. In general, the pressure drop across a filter system is increasing with the deposited particulate mass in the filter medium (Payatakes and Gradon 1989, Kanaoka and Hiragi 1990; Brown 1993). In conventional used depth filter systems operating flow velocities are roughly below 1 m/s. At this range of velocity, the particles deposit on the fiber. At flow velocities above 1 m/s particles are likely to bounce off or being blown off from the fiber. To detach particles of 10 µm from filter fibers, high flow velocities above 1 m/s are required (Löffler 1972). All findings by Löffler are valid for stiff fibers. By stretching the fiber, mechanical shear and tensile stress are induced to the compact structure and detachment is observed at operational flow velocities of about 0.4 m/s (Poggemann et al. 2021). The particle structures are weakened and detach more likely at lower flow velocities due to the stretching process of the fiber. In the investigations of Poggemann et al., only compact structures (based on inertial deposition) were obtained on the top side of the fiber. As shown by Kanaoka et al. (1986) there is a systematic relationship between the deposited structure on the fiber and the filtration velocity during the deposition process (Kanaoka et al. 1986). It is assumed that the overall morphology of the deposited particulate structure on a single fiber has an influence on the detachment behavior during fiber stretching.
To investigate this influence on the detachment behavior, a compact or a more dendritic and open structure is deposited on a stretchable single fiber. By applying a flow velocity of...
Enhanced nano-aerosol loading performance of multilayer PVDF nanofiber electret filters
W. W.-F. Leung*, The Hong Kong Polytechnic University, China
Aerosol loading behavior of PVDF nanofiber electret filters using neutrally charged nano- and submicron aerosols was investigated experimentally for the first time. The loading behavior include variations of filtration efficiency and pressure drop and distribution of deposited aerosols in the filters all having the same fiber basis weight (3.060 gsm). Through the filtration efficiency variations of uncharged/charged, single-/multi-layer filters with aerosol loading, it was observed that mechanical PVDF filters had continuously increasing filtration efficiency, while PVDF electret filters had initially decreasing and subsequently increasing filtration efficiency until reaching 100% due to diminishing electrostatic effect and enhancing mechanical effect. By combining the pressure drop evolution of different filters during aerosol loading and detailed SEM images of the loaded filters, we have demonstrated that multilayer PVDF filters, especially the electret ones, could significantly slow down the pace of filter clogging (skin effect) and increase significantly the aerosol holding capacity during depth filtration. Generally, the multilayer nanofiber filters received the most aerosol deposit during depth filtration, whereas the single-layer nanofiber filters with the same basis weight of fibers received the most deposit during cake filtration. The multilayer nanofiber filters had approximately...
A novel modular small-scale apparatus for continuous solid–liquid separation and washing of crystal suspensions
C. Steenweg*, A. Seifert, J. Habicht, K. Wohlgemuth, Technical University Dortmund, Germany
Control of product quality, such as particle size distribution (PSD), residual moisture and purity, is of high importance during pharmaceutical and fine chemical production processes. Each process step in the whole process chain can affect all following steps and thus may interfere with reliable in-spec production. During the last decade, a shift towards continuous manufacturing can be observed to eliminate the batch-to-batch variability. Thus, novel process concepts are required to replace or extend unit operations that have predominantly been batch operations, such as crystallization and subsequent solid-liquid separation, washing and drying.
Various concepts for continuous crystallization for small volume flow rates of 10 ‑ 100 mL min‑1 are available improving the critical quality attributes . However, within the crystallization process chain, further process steps like filtration, washing, and drying are required to obtain the final solid and dry product. Such techniques have been scarcely investigated in continuous operation mode in the typical API production scale of 250 - 1000 kg a-1.
Only few equipment concepts for the continuous downstream of crystalline products have been commercialized by now. Alconbury Weston Ltd. offers a quasi-continuous automated batch filtration with a semi-continuous inlet and solid discharge. Disadvantageously, buffer tanks for the slurry inlet are required, which entails several drawbacks regarding product quality, traceability and process efficiency. [2,3]
Continuus Pharmaceuticals Inc. provides a continuous rotary plate filter that was tested for volume flow rates in the range of 20 - 100 mL min-1. However, this device does not enable a deliquoring and further thermal drying of the crystals and the filter cake may not be uniformly dispersed radially on the filter medium. 
Thus, innovative process solutions for integrated downstream product design are required. We aspire to design, set up, and characterize an innovative continuous process concept for solid-liquid separation, washing, and drying of crystal suspensions that is connectable to different continuous small-scale crystallizers such as a MSMPR cascade, a continuous oscillatory baffled crystallizer or a slug flow crystallizer with small volume flow rates between 10 - 100 mL min-1.
This contribution will show the characterization of the innovative apparatus for small-scale continuous solid-liquid separation and washing...
Quantification of granule formation as a function of solubility in residual solvents
M. Siddique*, S. Ottoboni, C. Price, University of Strathclyde, UK; A. Laux, P. Mulheran, University Toulouse III - Paul Sabatier, France
Active Pharmaceutical products (APIs) are produced mainly by crystallization to form a high purity product with controlled particle size distribution.1 The crystallization process generates particles with the required physical properties and purity in suspension. The isolation (filtration, washing, and drying) process is needed to separate the pure product crystals from the impure mother liquor to produce dry, free-flowing particles while preserving the particle size distribution achieved by crystallization. Drying is the last and critical processing step in the isolation and purification of API crystals which is performed to remove the residual solvent remaining after filtration and washing. The effectiveness of the drying process affects the quality attributes of the final drug product, and it can impact the subsequent manufacturing steps, including blending and tableting.2
Residual solvent levels must meet ICH guidelines to guarantee patient safety. Traces of residual solvent may also affect the stability of the formulated product.3 API dissolves in the residual solvent left during drying tends to create "sticky" points at the contacts between particles, promoting solid bridges and being responsible for particle agglomeration.4 The residual moisture content and composition, solvent polarity5,6, surface tension7, and viscosity8 significantly impact agglomeration. The drying process can also impact on final drug product leading to non-uniform powder flowability, inconsistent drug product dissolution profile, and bioavailability. +
A series of experiments were performed to investigate the effect of residual solvent on isolated, dried particles. The system...
Highly efficient extraction of egg yolk powder thanks to continuous filtration and drying
M. Rahmann*, BHS-Sonthofen GmbH, Germany
Significant savings, greater yield and increased throughput – a pharmaceutical company benefits from various improvements as a result from switching to a continuous extraction process and leaving the traditional batch operation behind. Key components that make these improvements possible are the Indexing Belt Filter and the AVA continuous horizontal dryer from BHS-Sonthofen.
Previously egg yolk powder extraction was a complicated slurrying process with dilution washing, having a series of equipment and resulting in tremendous resources requirements. The user replaced this complex batch process with a continuous process. BHS analyzed the existing process and tested alternative options in the laboratory. As a result they recommended the use of a belt filter as the most suitable solution in combination with a continuous, efficient contact dryer.
BF belt filter from BHS increases yield of phospholipids
HTK-T continuous dryer dries egg yolk powder gentle and energy efficient
Filter press solid liquid separation: comparative study on cake drying and washing performances with different plate designs.
N.M. Finocchiaro*, F. Kaswalder, A. Grosso, Aqseptence Group s.r.l., Italy
In the last few years, sludge treatment with filter presses has become more and more common in the mining industry as well as in other sectors. These machines offer great advantages: first, the dewatering level that can be reached with filter presses is much higher compared with other separation technologies, and this grants a substantial water recovery level. Moreover, filter presses are very versatile machines that can easily adapt to changes in both production capacity and solids concentration.
The mining sector requires higher and higher performances, in particular on residual moisture content in cake and machine’s throughput. The optimization of the filter press process parameters is therefore essential to meet customers’ needs.
This paper presents the results of two case studies where we compared different plate designs by conducting bench-scale simulations.
The first case study described in this paper is focused on the analysis of cake drying performances with different plate types. Plates used had different arrangements such as different membrane types and a different positioning of drainage holes. The parameter monitored was the residual moisture content in cake. This study was carried out on a coal concentrate.
The second case study was focused on the fluid dynamics of the washing liquor inside the filtration chamber in case of cake washing. The movement of a fluid inside the chamber was analysed by using a tracer...
In-situ cleaning process of chamber filter presses with sensor-controlled and demand-oriented automation
P. Morsch*, M. Gleiß, H. Nirschl, Karlsruhe Institute of Technology (KIT); R. Werner, D.U. Geier, T. Becker, Technical University of Munich, Germany
Cleaning plants for the chemical industry is essential to avoid cross-contamination, especially in batch operation, and thus to ensure safe production. This applies in particular to solid-liquid separation processes and to filtration. Due to the difficult to clean surfaces of filter cloths, these devices have special requirements for cleaning. The cleaning of filters is therefore often designed conservatively, which is equivalent to excessive cleaning. A demand-oriented cleaning method based on image analysis offers a lot of optimization potential in this area, especially to reduce the required cleaning agent, document the cleaning result and reduce the amount of wastewater....
Regeneration of filter press fabrics in the mining sector
B. Fränkle*, Karlsruhe Institute of Technology (KIT), Germany
Generally, filter media used in filter presses have a limited operation life. Beside mechanical damage, there is a growing deposition of fine particles with increasing filtration cycles, the so-called blinding, inside the filter cloth. Resulting decreasing pore diameters not only affect the efficiency of the filtration process itself by increasing the filter medium resistance, but also makes it more difficult to regenerate the filter press between the individual cycles, e.g. leading to an insufficient cake discharge. Since tailings filtration requires handling of large process flows containing a significant fraction of particles in the lower micrometer range an investigation into media rejuvenation is of interest.
Therefore, the regeneration of three industrial used cloths from a gold, silver and an iron ore mine provided by FLSmidth differing in cycle amount, material, weave and fiber type is investigated by using different agents as well as changing exposure times and concentrations and ultrasound. The effectiveness of the different cleaning procedures is evaluated based on the process engineering parameters permeability and pore size in flow measurements and permeability tests. Subsequently, an additional elementary analytical examination of selected sample states is carried out to determine whether the composition of the tailings influences the regenerability. Possible negative effects on the mechanical properties of the cloths, both by the high number of filtration cycles and by the cleaning process, are analyzed by means of tensile tests...
Day: 09 March 2022
Time: 09:00 - 10:15 h
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Enhanced performance for high efficiency filter media design with a sustainable competitive advantage
N.W.M. Edwards*, A.P. Slater, Lenzing Fibers Grimsby Ltd., UK
The Lenzing Group stands for the ecologically responsible production of high-quality, specialty fibers made from the renewable raw material wood. The LENZINGTM Lyocell manufacturing process is distinguished by its conversion efficiency and closed cycle design, which recovers, purifies and re-uses the process solvent and process water...
Biopolymers in filtration technology: Effects of PLA on pleating characteristics of synthetic filter media
G. Müller*, D. Weidt, F. Bauer, Sandler AG, Germany
In HVAC filtration and other sectors, such as automotive filtration, the trend for decreasing installation spaces requires smaller filters without compromising their performance and durability. Hence, the demand for pleatable filter media, which provide largest possible filtration surface in limited spaces, is continuing to grow.
Today, the pleatable filter market is dominated by glass fibre paper treated with chemical binders or adhesives. However, even small amounts of water or moisture can result in a reduced fold stability leading to the final collapse of the folds and, thus, of filter performance. Moreover, glass fibre filters may easily get damaged during production, assembling or due to in-service impact events causing fibrous airborne matter. Such fibre shedding poses health risks to skin, eyes and to the respiratory tract.
Self-supporting synthetic filter media compensate these drawbacks. When compared to traditional glass fibre, the high resilience and mechanical stability of such synthetic media leads to an extended lifetime and an excellent price-performance-ratio. Moreover, fibre shedding is not present. However, they possess also disadvantages. Synthetic filter media are (a) usually based on petrochemical raw materials such as PP (polypropylene) or PET (polyethylene terephthalate) and (b) show difficulties during pleating. The latter is visible in the lack of contour precision and pleat stability, which is most dominant for rotative pleating systems.
As the sustainable use of resources and the impact of products on the environment are shifted towards the centre of public attention, many efforts are made to exchange petrochemical by bio-based materials. Polymers such as polylactide (PLA) offer promising means for such applications due to their specific deformability, stiffness, electrical chargeability and sustainability.
To our knowledge this is the first study that describes the effect of incorporation of bio-based polymers into the meltblown on pleat characteristics. The work addresses the use of biopolymers from the perspective of processability and pleatability. The medium can either be based on the incorporation of renewable resources as component in a polymer blend, a meltblown monolayer or as a single layer within a composite. It is believed that material such as polylactide acid leads to a significant improvement in pleat performance.
The investigations covered the classical scale-up production process from laboratory to semi- and industrial scale. Two critical technical parameters were selected to quantify the pleatability of a medium: CRA (Crease Recovery Angle) and ∆ CRA (angle variation). Scanning electron microscopy (SEM) was used to study the morphology of the nonwovens. To investigate the thermal behaviour and the influence of crystallinity on CRA differential scanning calorimetry (DSC) was used. In addition, industrial conversion tests on a rotary mini pleat machine were performed.
Our investigations show that...
Comparison of Bekipor® filter media to alternative metallic solutions
A. Goux*, S. Vandendijk*, Bekaert Fiber Technologies, Belgium
Bekipor® filter media consists of one or more sintered web layers of very fine metallic fibers (1 to 40µ). The multi-layered structure of the media provides superior filtration efficiency, high contaminant (dirt) holding capacity and low pressure drop, which increases the on stream lifetime of the filter element. Unlike alternative materials with binder, fiber migration is not an issue as the fibers are physically bonded together. Bekipor® metal fiber media has the advantage of high corrosion and temperature resistance, high heat dissipation and mechanical resistance. All of the characteristics are highly beneficial in many applications. Bekipor® sintered metal fiber media are widely used for over 40 years in liquid and gas filtration for various industries such as polymer production, chemical processes, power generation or oil filtration. Filters made out of Bekipor® metal fiber media are cost effective, as they will lead to minimal downtime and maintenance. Moreover, the filter elements can be easily cleaned off-line to be reused. This all leads to the best Total Cost of Ownership (TCO).
An overview of the design and manufacturing of this media will be provided. A recent independent testing of the Bekipor® sintered metal fiber media compared its filtration performances in term of filtration efficiency, permeability, and dirt holding capacity to commercially available woven wire mesh and sintered metal powder. This study shows that...
New developments in woven wire filtration media: 3D high performance filter cloth – woven wire mesh combinations in solid-liquid separation
F. Edelmeier*, F. Meyer, Haver & Boecker OHG, Germany
Previous filter cloths with small pore sizes lead to reduced flow rates and significant pressure loss in the production process. The cloth structure of a newly developed three-dimensional weave increases the number of pores and thus the open surface over the same area. For a given pore size, the flow rate is more than doubled compared to conventional Dutch Weaves. The pore size within a batch can be calibrated as desired from 5 µm to 40 µm. Conventional woven wire filter cloths can cause turbulences that affect the filtration process at high flow rates. Turbulences with the 3D-filter cloth is effectively avoided. Its pore size can be calculated precisely in advance and adapted to the respective requirements. The mathematical formulae for determining permeability were developed in cooperation with the University of Stuttgart within the scope of AVIF projects A224 and A251, and experimentally validated by glass bead tests and air flow-through measurements. These predictable pore sizes can achieve extremely high cut-points and dimensional stability. The depth structure of the new woven wire filter cloth facilitates high separation efficiency without rapid blinding. This leads to longer filtration processes between cleaning intervals and longer service life for greater production reliability. The 3D metal filter cloth is woven from standard diameter wires. Moreover, it is possible to weave special materials such as Alloy 310 S, Hastelloy C 22, Inconel 600 or titanium even in the small pore range. Thus, for the first time, filter cloth with pore sizes below 40 µm can be manufactured in corrosion- and temperature-resistant alloys.
The effect of different gradient structures on the load-dependent fractional separation efficiency and its dirt hold capacity have been subject of design considerations in single and multi-layered woven wire mesh combinations in solid-liquid and solid-gaseous separation. In cooperation with the Institute of Mechanical Process Engineering in Stuttgart (IMVT) different gradient structures of wire mesh filtration media were investigated as to their influence on the load-dependent fractional separation efficiency (FAG) as well as their dirt holding capacity. In addition, different offline measurement techniques and particle systems and their influence on the result of the FAG and the dirt hold capacity were investigated and evaluated....
A woven wire mesh for highest separation performance at lowest power consumption
M. Müller*, Spörl KG, Germany
The core element of every filter unit is the filter medium. To select a filter medium for a specific filtration task, also commercial aspects and the ability to form the medium into the desired design without damaging it have to be considered. Nevertheless, the main request is to ensure, that the medium complies with the filtration requirements of the process. Thus, the pore size needs to be selected so small that the desired purity of the filtrate is achieved. At the same time, the filter medium needs to be able to withstand the chemical, thermal and mechanical stresses which occur. For a resource-saving filtration process, the filter medium should have a high permeability and a large dirt-holding capacity, which is associated with a long service life. For filtration processes with a large dirt load which has to be separated, the filter medium should be easily cleaned e. g. by pulse-jet or back flushing. Many of these filtration properties mentioned are contrary to each other and cannot be combined in one filter medium at the same time. For example, a high separation efficiency due to a small pore size is always associated with a high flow resistance.
There is a wide range of filter media of different structure made of various materials. For demanding process conditions, for instance in the form of high process pressures and temperatures or if sharp-edged particles have to be deposited, metallic filter media and in particular metal woven wire meshes are often used. Dutch Twilled Weaves as one of the weaving types of woven wire meshes are established filter media for the deposition of finest particles down to the single-digit micrometer range and to realize highest separation performances already in the unloaded state. To achieve these small pore cross-sections, the weft wires need to be woven as closely together as possible. This results in a fabric with a low porosity, low free passage area and low number of pores, and thus a high pressure loss and power consumption of the filtration process. Furthermore, the narrowest pore cross section is located inside the fabric, which is why this weaving type is very difficult to clean. Frequent replacements of the filter elements made from them is necessary, which leads to high maintenance costs and long plant downtimes.
An alternative weaving type to produce finest wire meshes are the so called Betamesh-PLUS fabrics. In these plain weave fabrics, the wire diameters of the warp and weft as well as the pitches are combined in such a way that these fabrics are characterized by...
Development and evaluation of precision woven wire cloth for sieves and filters, an ultrafine woven wire cloth with a square opening size of 13 µm and mesh counts of 977 wires per linear inch
S. Nojima*, N. Hirajo, S. Shimokomaki, T. Matsumoto, Y. Mizuguchi, ASADA MESH Co. Ltd., Japan
With narrow square opening size distribution woven wire cloth guarantees an excellent separation and classifying accuracy. Stainless-steel is a common material for woven wire cloth, and due to the thermal and mechanical strength of stainless-steel and its high chemical stability, it can be used in demanding conditions, such as at high temperatures and high pressures. Therefore, the woven stainless-steel wire cloth has a wide range of applications as sieves and filters. We are an ultrafine woven wire cloth manufacturer and were the first in the world to successfully produce a precision woven stainless-steel wire cloth with a square opening size of 13 µm (0.0005 inch) and 977 wires per linear inch (product name Sieve SV13/13, hereafter called #977). Furthermore, a technique was also developed for weaving #977 with a width of 1220 mm. This abstract gives an overview of the evaluation of #977's square opening sizes.
Until now, ASTM E-11 designates nominal opening sizes of industrial woven wire cloth for sieving down to 20 µm (0.0008 inch) with 635 wires per linear inch. Our product list includes a woven stainless-steel wire cloth with a square opening size of less than 20 µm with a square opening size of 16 µm (0.0006 inch) and 795 wires per linear inch (product name Sieve SV16/16, hereafter called #795). However, no industrial standards for measuring the square opening size of #977 and #795 have been defined. In this study, the square opening size of #977 was measured using an image analyzer, PoreSizerTM (Whitehouse Scientific Ltd). The square opening size of #977 ranged from 11.0-15.7 µm, with a mode diameter of 13.0 µm and σ = 0.667. These results confirm that #977 is a high-precision woven wire cloth...
Feasibility of high-temperature electrostatic precipitation for the removal of nanoparticles: A case study on iron oxide separation at up to 800 °C
P. Bürger*, U. Riebel, Brandenburg University of Technology Cottbus - Senftenberg, Cottbus (BTU)
The removal of nanoparticles, especially from hot gas streams, is a challenging task and often associated with high energy demands. However, processes such as catalyst production, additive manufacturing and pyrolysis require an efficient way of particle separation. Ceramic filters are state of the art above 400 °C but they cause high pressure drops. The common assumption that electrostatic precipitation is not feasible above 400 °C at atmospheric pressure due to the convergence of corona onset voltage and sparking voltage appears to be short-sighted.
This case study evaluates the performance of a high-temperature electrostatic precipitator (HT-ESP) between 400 – 800 °C for both discharge polarities. The tube-type ESP with...
SMF® - Innovative thin metallic filter media for industrial filtration applications
S. Steigert, K. Schrewe*, HJS Emission Technology GmbH & Co. KG, Germany
More than 2 million m² of HJS Sintered Metal Filter (SMF®) material have been produced within the last 15 years, with a peak production of 300.000 m² p.a.. The SMF® material is a thin (< 0.5 mm) porous sintered metal in which a precisely defined stainless steel powder is sintered with an expanded metal carrier. This results in a thin, mechanically and thermally very stable filter medium, which can be treated in further processing similar to sheet metal. The SMF® basis material is industrially manufactured as quasi endless sheet with a width of 125 to 130 mm. Approved for hot gas and exhaust filtration, the material is further processed into filter modules that are designed for the named applications.
These SMF® modules are proven for a very large number of exhaust gas filtration applications used by vehicle manufacturers for applications that are subject to the current European emission legislation and thus strict requirements for particle number reduction. Furthermore, there are first applications in the industrial filtration of gases. In addition to the thermal robustness of the filter material, the high retention capacity and good cleanability of inert filtrate is also a key factor.
The aim is to use the known advantages of the thin foldable SMF® material, such as sharp separation efficiency or good cleanability, for new industrial filtration applications...
A CFD study on gas flow and liquid spray atomization using a spiral nozzle in a wet scrubber
O. Kristof, P. Bulejko*, T. Sverak, J. Kalivoda, Brno University of Technology, Czech Republic
This work is a first attempt to simulate liquid spray atomization using a spiral nozzle in a spray. Spiral nozzle has a special non-axisymmetric geometry able to create a spray pattern in the form of three concentric hollow cone liquid sheets. This geometry leads to a mass transfer intensification among pollutant gas and the absorption liquid as well as a better capturing efficiency of PM. Thus, only one nozzle can be used instead of a system of several nozzles in the spray column. First, we simulated the gas phase distribution inside the scrubber chamber using a Reynolds stress model with the coupled solving scheme. This model is suitable for description of extremely turbulent flow. Second, we used a two-phase VOF model to investigate basic parameters of liquid flow escaping the spiral nozzle (refer to figure below). Both simulations can then be used to study liquid shower in the scrubber in a counter-flow with the entering polluted gas using a DPM model of the sprayed liquid. The DPM model provides us with information about distribution of liquid fragments and individual droplets to estimate the interface area necessary for adequate mass transfer rate. Result of this study can help to better optimize gas scrubbers in terms of capturing efficiency, size, usage/regeneration of absorption liquids and energy demands, which is tightly related to acquisition and operating costs...
Re-wetting during belt filter press operation
G. Krammer*, F. Mazzi, Graz University of Technology; R. Raberger, Andritz AG, Austria
Belt filter presses are widely used for the separation of solid particles from liquids. In a first stage, the free draining liquid of a suspension is removed by a gravity table. This pre-thickened suspension is further compacted by feeding it through two converging filter belts, i.e., the wedge zone to form a filter cake that is sufficiently stable to cope with increasing press forces exerted on the cake during a sequence of subsequent rollers. With the diameters of the rollers decreasing, the operation parameters belt speed and belt tension as well as the geometric set-up resulting in the enlacement lengths, the gradual, though step-wise increase of the exerted areal pressure as well as the respective exposure time of the cake are ensured to meet the targeted cake dryness and specific throughput.
Under the premise that no gas bubbles are present in the cake during its formation, mere press filtration results in a filter cake that is fully saturated by liquid. Further reduction of the liquid content is accomplished by liquid evaporation (thermal drying or desorption) or liquid displacement by gas blowing. However, a filter cake that has elastic properties will expand when the pressure is released. Under the premise that adjacent free liquid is present and sufficient time is given, such an expanding filter cake can pick up liquid that was removed from the cake already previously. However, when time is too short and/or liquid for re-wetting is lacking, a filter cake is obtained with a saturation below one, i.e., with a higher cake dryness and shrinking cracks may form.
In the laboratory two different aqueous suspension were investigated, hard coal and a waste material containing metal and organic matter. Mimicking the belt filter process, the free liquid was drained before the pre-thickened suspension was compacted by applying normal pressure. The resulting filter cake was fed to a laboratory roller test set-up at conditions typical for large-scale applications. The filter cake dryness was determined with and without a liquid suction and storage layer positioned between the rubberized and dense roller and the filter medium. The results show...
Vibration-enhanced compaction of compressible filter cakes for mechanical dewatering on a vacuum belt filter
T. Yildiz*, H. Nirschl, Karlsruhe Institute of Technology (KIT), Germany
Cake filtration is a proven method for separating solid particles from a suspension. After cake formation, there is a particle network whose pores are filled with liquid. To reduce the residual moisture of the filter cake, mechanical dewatering measures are a more cost-effective alternative to thermal drying. After cake formation, gas pressure is applied to the filter cake, allowing the liquid to be largely displaced from the pores of the particle network. This can lead to the formation of shrinkage cracks, especially in fine-particulate products, which result in higher gas consumption and thus higher process costs. It is known from previous research activities that shrinkage cracks during liquid removal can be prevented by pre-compaction of the filter cake. Furthermore, compaction contributes significantly to further dewatering of the filter cake. Since the required pressing pressure can be very high, depending on the particle system, and this measure is therefore often not feasible on a continuous technical scale, alternative compaction methods are desirable. An innovative method is the application of an oscillatory shear into the filter cake using significantly lower pressing pressure, which has already been successfully tested on a discontinuous laboratory scale for compressible materials. It was shown that vibration-enhanced pre-compaction reduces crack formation and even causes a higher compaction state and a lower residual moisture compared to pure pressing for some materials.
The aim of the current research project is to investigate the applicability of the novel compaction process to a continuous filter apparatus...
Electro-assisted filtration of microfibrillated cellulose: insights gained from experimental and simulation studies
N.K. Karna, A. Lidén*, H. Theliander, Chalmers University of Technology; J. Wohlert, Wallenberg Wood Science Centre - Royal Institute of Technology, Sweden
Microfibrillated cellulose (MFC) has gained a lot of attention during present decade owing to its sustainability potential, availability for surface modification and mechanical properties. Commercial scale up of this material is, however, restricted due to the lack of an energy efficient production and transportation process. One of the main factors, in the present process solution, that increases the energy demand during the production and transportation is the high water content of the process streams and the final product. MFC is often produced in dilute suspension and hence a lot of water needs to be separated to allow for an economical transportation and/or further modifications. Although dewatering of MFC is a key factor to commercial scale up of the process, progress is still needed. Current suggested methods for the water removal greatly rely on drying techniques, all of which are rather energy intensive and may lead to irreversible particle aggregation which can cause difficulties in dispersibility.
A preceding mechanical dewatering step, with a lower energy demand than that of the drying, may be added to reduce the total energy demand of the production process. The most common method of solid-solvent separation is mechanical dewatering by filtration; however, it is not suitable for MFC due to the large surface area subjected to the liquid flow and because of mechanical interlockings and friction between the fibrils that may cause extensive filtration resistance. A means to aid the filtration is to apply an additional force to the particles in the solution. In this context, an electro-assisted filtration technique, in which an electric field is applied across part of the filter chamber may prove to be beneficial. The application of an electric field introduces several electrokinetic phenomena which can be beneficial to the dewatering process.
Considering the benefits of electric field and complexity of the material to be filtered; an electro-assisted filtration of MFC produced...
Membrane bioreactor for the cleaning of surface water of a solid waste treatment site
T. Sieder*, B. Mayr, EnviCare, Austria
At solid waste treatment facilities, waste is partially stored outdoor on sealed surfaces. Therefore, rainwater might be considerably polluted with organic and inorganic compounds, depending on the leaching behaviour of the waste pile.
The discharge of rainwater is by law only allowed into storm water or combined wastewater sewers. If it is going to be discharged into a receiving water body, anthropogenic polluted surface water has to be treated according to the state of the art. The so-called first flush, the rainwater from the first 15 minutes during heavy rain events, has to be collected, stored and cleaned properly. Normally the water quality after the first flush already allows for direct discharge.
High fluctuating quantities and qualities of this surface water with differing temperature causes high demands on the treatment technology. In the case presented in this paper the COD (Chemical Oxygen Demand) concentration in the inflow ranges from 50 mg/l to 1,000 mg/l, in addition there can also be fluctuating and substantial nitrogen and phosphorus loads. In biological treatment plants, the retention of activated sludge has to be guaranteed for sudden heavy rain events as well as for longer dry periods. Membrane bioreactors meet both criteria while in a conventional sedimentation-based system, the activated sludge flocs will be washed out.
In membrane bioreactors (MBR) biological wastewater treatment is combined with membrane technology. Organic compounds, nitrogen and phosphorus are removed in aerobic processes. Ultrafiltration membranes prevent biomass and inert particles from wash-out. In this case hollow fibre membranes with a cut off of 50 nm are used.
This paper presents the design, construction and operation of an MBR plant for the cleaning of surface water of a solid waste treatment site...
Technical and economical evaluation of a membrane-based filtration process to remove micropollutants, resistant bacteria/genes and nutrients from treated wastewater
M. Werner*, D. Schreier, MANN+HUMMEL Water & Fluid Solutions; A. Merz, Darmstadt University of Applied Sciences, Germany
Since the last decade, the global concern regarding the release of harmful substances to the aquatic ecosystem is growing.
Chemical substances referred to as “micropollutants” originate from the production and use of products such as pharmaceuticals, biocides, pesticides, industrial and domestically applied chemicals, or personal care. These substances are frequently entering the aquatic ecosystem occasionally and via diffuse paths. The main path of entry represents industrial and municipal wastewater which is collected and treated in wastewater treatment plants (WWTPs) and subsequently discharged to waterbodies.
In addition to micropollutants the emergence and increasing spread of antibiotic resistant bacteria (ARB) and genes (ARG) holds a growing risk to environmental and public health. In several studies ARB and ARG have been extensively detected in wastewater. Published data illustrated a significantly higher proportion of ARG in raw and treated wastewater compared to surface water. The prevalent conditions in WWTPs, especially the biological treatment, tend to favour the accumulation and distribution of ARB to receiving waterbodies.
To deal with micropollutants in the outlet of WWTPs, processes e.g. ozonation, granulated activated carbon filtration and powdered activated carbon filtration have been implemented in plants all over Central Europe to further purify treated wastewater. However, those processes do not guarantee a removal of ARB/ARG. The challenge to significantly reduce micropollutants and separate ARB/ARG from treated wastewater led to a rising demand for additional filtration processes and triggered the development and application of membrane-based filtration processes which provide a physical barrier for harmful substances.
Such a process represents the “BIO-CEL® Activated Carbon process”, a combination of submerged ultrafiltration (UF) membranes, the dosage of Powdered Activated Carbon (PAC) and precipitants. A detailed description of the process can be found in M. Werner, M06 FILTECH 2019. In order to provide a customized solution for advanced wastewater treatment, MICRODYN-NADIR has been operating pilot plants at five locations since 2016 by testing different feed water as...
End-of-Life RO membranes: from autopsy to wastewater treatment
M. Pontié*, Angers University; S. Awad, IMT Atlantique, France; B. Chaouachi, ENI Gabes, Tunisia; F. Seibel, V. Barbosa Briao, Universidade de Passo Fundo, Brazil
The overall objective of the present work is to estimate the degradation level of end-of-life reverse osmosis (RO) membranes sampled from different countries (Senegal, Mauritania, Tunisia, Brazil, Israel) in terms of water permeability, salts rejection, roughness changes and chemical analysis by following a membrane autopsy methodology, in order to help to manage those products made of plastics. SEM/AFM and EDX experiments completed the approach showing i.e. crystals (i.e. CaCO3) or bacteria as (bio)fouling agents deposited.
Furthermore a mechanistic approach using Spiegler–Kedem–Katchalsky mass transfer model convective vs diffusional mass transfer was studied. We defined a novel adimentionnal number (denoted Pe′) to estimate the weight of diffusion vs convection mass transfer. Also a transmembrane streaming potential measurement tool help us to observe a displacement of the isoelectric point (IEP) of the pristine membrane i.e 5.7±0.3 to 4.5±0.3 in comparison to the old one illustrating a chemical modification of the inner active layer suspected to be due to (bio)fouling residuals deposition. Such end-of-life RO membranes were oxidized with chlorine attacked and tested to treat various waters : brackish water, surface water and wastewaters, (1,2).
At the end the possibility to transform end-of-life RO spacers to alternative fuels via pyrolysis is studied...
Day: 09 March 2022
Time: 10:45 - 12:00 h
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Simulation of solid-liquid separation processes: Challenges in modeling and experimental validation
Prof. Dr.-Ing. Sergiy Antonyuk,Technische Universität Kaiserslautern, Germany
With the rapid increase in computing power, numerical simulation is becoming increasingly important for the prediction and description of solid-liquid separation processes. Numerical studies can improve knowledge of complex separation mechanisms and support the model-based optimization of existing and the development of novel separation processes.
The approaches used for the modeling and simulation of solid-liquid flow processes differ in the resolution of the flow and boundary layer, consideration of physical effects, microprocesses and interactions as well as the computational effort. This contribution gives an overview of the different approaches and demonstrates their suitability and challenges for the description of the transport and separation of fine particles by comparing simulations with measurements.
The focus is on the detailed description of the separation of particles from suspensions in complex nonwoven structures or in a filter cake by taking into account micromechanisms and real filter medium microstructure. The particle-particle, particle-fibre and particle-fluid interactions, formation and breakage of aggregates, clogging of pores and the compressibility of particles in the filter cake can show a major influence on the filtration process. For the description of these microprocesses, the particle separation can be simulated with the coupled Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD). The contacts between particles and fibres are calculated numerically by DEM with force and angular momentum balances, where contact deformation and adhesion as well as drag and viscous forces due to flow obtained with CFD are considered. The kinematics and dynamics of each individual particle and the entire particle collective in the suspension can be obtained. In contrast to other methods, DEM is able to consider such effects as particle size distribution and irregular shape, plastic deformation, friction, rotation, sticking of particles and breakage of agglomerates. The real microstructure of the filter medium can be obtained by computed microtomography and implemented in a 3D model for simulation of particle deposition.
The recent applications of DEM-CFD methods in the field of filtration are presented. The measurement methods for the parameter estimation (mechanical particle properties, friction, restitution coefficient, adhesion) and validation of the DEM-CFD model will be explained with examples of experiments...
Influence of the layer structure on the filtration performance of fiber fleece-woven wire mesh-composite cloths
M. Müller*, Spörl KG, Germany
At the conference of the last Filtech in 2019 the different methods to increase the areas of application as well as the filtration performance of metal woven wire meshes were presented by the author . With their narrow pore size distribution metal woven wire cloths guarantee an excellent separation and classification accuracy. Due to their high chemical, thermal and mechanical resistance, wire meshes as metallic filter media can be used in demanding operating conditions, for instance in the form of high process pressures and temperatures or if sharp-edged particles have to be deposited. Depending on the combination of the warp wires and the weft wires during the weaving process, the production of different types of weave with different aperture sizes and filtration behaviors is possible.
One of the clarified methods to increase the filtration performance is the coordinated combination of a metal wire mesh with a metal fiber fleece on the upstream side. In the so-called Compomesh-media the fiber fleece as a depth filter medium ensures a high dirt holding capacity and prevents the metal wire mesh as surface filter in the second layer to be blocked. Due to its narrow pore size distribution the wire cloth acts as a control filter and guarantees a certain purity of the filtrate in every loading state. To prevent the discharge of nonwoven fibers to the filtrate side, in the Compomesh the individual filter layers are sintered together.
By combining metal fiber nonwovens with different properties, such as fiber diameter, specific weight or porosity, with metal wire cloths of different weaving type and aperture size, the filtration performance of the composite cloth Compomesh can be adapted to the requirements of the filtration process....
Virtual production of filter media using simulation driven design
A. Schmeißer*, S. Gramsch, W. Arne, R. Wegener, Fraunhofer Institute for Industrial Mathematics (ITWM); F. J. Hahn, T. Gose, A. Koronai-Bauer, K. Riedinger, F. Keller, MANN+HUMMEL GmbH, Germany
The emission of fine dust from industrial processes and traffic as well as contamination-sensitive manufacturing technology and clean rooms call for the provision of clean indoor air and therefore requires highly efficient air filter media. Considering the rise in energy cost and the necessity of worldwide CO2 reduction the energy consumption of air filters becomes increasingly relevant. Developing filter media featuring both highest levels of filtration efficiency and lowest possible pressure drop poses an optimization challenge, as both design goals are conflicting.
The increased demand for high performance filters gives rise to challenging engineering tasks to develop efficient filters for different applications. An important aspect in the research and development of new filter media is virtual production with software simulation. A common approach for this models filters as fibrous media with given statistical properties. Using a simulation loop, these properties can be designed to yield optimal performance. However, this does not yet account for how a filter medium with the designed properties can be produced in an actual production process. Thus, the realization of virtually predicted optimal filter media prototypes requires extensive validation in trial runs and may sometimes not be achievable.
We aim to address this issue by means of a novel, holistic approach to the virtual media development. Within the scope of a publicly funded research project, we develop a simulation chain for the simulation-driven design of new filter media demonstrated exemplary using the spunblown process.
Our coupled approach uses a complex chain for the complete simulation from the production process to the final product and its filtration properties, along with a validation of results using experiments on the corresponding real filter media. Instead of the conventional parametric material model of the resulting filter media, we use a fully physical model of the production process starting from the spinning of filaments at the spinneret, down to the stretching in turbulent airflow and web forming of the nonwoven material. The visco-elastic material models used can...
Adding value to filtration media using metal additive manufacturing
N. Burns*, M. Burns, Croft Additive Manufacturing Ltd; D. Travis, L. Geekie, Croft Filters Ltd, UK
Croft Filters manufactures customised filtration solutions for industrial processes. Most filtration media are manufactured conventionally but almost all manufacturing processes involve both automated and hand operations. Filter media design is driven by the required filtration level. Delivering the filtration media with the maximum open area will provide a greater efficiency. However, operational pressures may require the woven wire mesh to be supported, or consist of one or more layers also with support. This decreases the overall open area and increases the pressure drop across the filter. Any changes in design that can decrease the pressure drop across the filter will increase the efficiency of the filtration media.
Selective Laser Melting (SLM) Additive Manufacturing (AM) technology manufactures components layer by layer which delivers design freedom to produce complex geometry components. The manufacturing process has been utilised to create innovative AM filters.
The aim is to demonstrate the wide range of added value that the AM process can deliver to improve filtration filter media efficiency as well as filtration media through an alternative manufacturing process...
Tasty wash liquor – Coffee extraction from the perspective of filter cake washing
M. Kuhn, V. Pannusch*, H. Briesen, Technical University of Munich; T. Sprott, B. Hoffner, Mannheim University of Applied Sciences, Germany
Coffee is a valuable trading commodity and an important good of consumption. In recent years, the coffee beverage was additionally promoted as luxury food similar to red wine in a movement called the “third wave” of coffee. Within the “third wave” also various brewing methods have been (re-)discovered and coffee extraction itself has seen a growing interest. This trend, in turn, brought along an increasing number of academic studies on coffee extraction, a process whose influence on the final beverage has been underestimated for a long time. Recent modeling approaches now describe coffee extraction in terms of mass transfer rates, diffusion, dispersion, and convection. A first comparison of coffee extraction with filter cake washing shows that similar physical effects prevail in both cases and that measured concentrations at the outlet exhibit a comparable dynamic behavior. This analogy motivates a systematic juxtaposition of the two fields of research.
In this contribution, we therefore compare recent insights on coffee extraction with approaches and findings on filter cake washing. Physical phenomena and their incorporation in the corresponding washing and extraction models are discussed. The explanatory power of different modeling approaches is examined and the potential of transferring models and process strategies between filter cake washing and coffee extraction is assessed...
Fluid and impurity transport during online isolation experiments conducted with x-ray tomography
S. Ottoboni*, M. Shahid, A. Martin, C. J. Price, University of Strathclyde; T. Kathyola, G. Das, S. Schroeder, University of Leeds; S. Marathe, C. Rau, K. Wanelik, Diamond Light Source, UK
The pharmaceutical industry requires active pharmaceutical ingredients (APIs) to be pure with the required particle size distribution. Investigations of fluid flow and porosity in porous beds using FEM, or synchrotron-based X-ray tomography have been reported.1-7 In this study the evaluation of fluid flow and impurity transport during filtration, washing a drying are observed using tomography to visualise the location of impurities during incomplete and complete washing, consequences of non-ideal filtration and washing, and residual mother liquor inclusions after washing and link these with agglomeration during drying. A pre-formed slurry made with API particles, impure saturated crystallization solution was filtered to remove the mother liquor to dryland or breakthrough. The effect of particle size distribution was evaluated using three different particles grades. The effect of crystal shape was studied using paracetamol as test compound. Iodine was used to mimic impurities dissolved in the mother liquor. The filter cake was washed with two different solvents to displace the remaining impure solution. Cake drying was performed at ambient temperature with flowing gas. The data collected during the 3D X-Ray Nano-tomography were reconstructed to generate 3D images of the solid cake fraction, where the distribution of larger particles and the particle layering effect were observed (TBTH) and the pore cake fraction where the X-ray absorption indicated the presence of iodine (TBSP). The pore cake fraction 3D structure was used to identify...
Integrated filtration and washing modelling: optimization of impurity rejection for the filtration and washing of active pharmaceutical ingredients
S. Ottoboni*, B.A. Mehta, E. Gramadnikova, C.J., Brown, University of Strathclyde; N.A. Mitchell, Siemens Process Systems Engineering Ltd. , UK
To facilitate integrated end to end pharmaceutical manufacturing using digital design, a digital tool capable of transferring material property information between operations to predict the product attributes in integrated purification processes has been developed. The focus of the work reported here combines filtration and washing operations commonly used in active pharmaceutical ingredient (API) purification and isolation by combining predicted and experimental data generated during upstream crystallization process. In detail, this work focuses on the development of a mechanistic model-based workflow for the optimization of an integrated filtration and washing model, with a view to minimize impurities in the isolated cake...
Electrospray deposition of polyelectrolytes for tailoring physicochemical properties and enhancing filtration performances of commercial UF membranes
S. Déon*, E. Korzhova, P. Fievet, Université de Bourgogne Franche-Comté, France
Compared with reverse osmosis and tight nanofiltration membranes, ultrafiltration membranes allow large permeation flux with relatively low applied pressures. Unfortunately, rejection performances are often low due to large pores and especially that of divalent cations (such as heavy metals) is impeded by the usual negative charge of commercial membranes. Hence, the widespread use of nanoporous membranes in the removal of ionic contaminants requires the adjustment of their physicochemical properties to allow adequate ion rejection and fouling mitigation. In this study, it is proposed to tailor physicochemical properties of a commercial low molecular weight cut-off ultrafiltration membrane by electrospray deposition (ED) of polyethylenimine (PEI) and polystyrene sulfonate (PSS). This self-assembly of positive and negative polyelectrolyte layers is based on electrostatic attraction between polymers (membrane and polyelectrolytes) exhibiting opposite charge sign. The electrospray deposition is a common technique which, up to now, has not often been used for membrane modification. This technique consists in spraying fine droplets of polymer solution on the membrane surface under a high voltage between the needle containing the solution and the metallic support on which the membrane is stuck. Compared with classical dip-coating technique, the advantages of this process are the small quantities of polymer required and the inhomogeneous polymer dispersion at the membrane surface.
It is shown in this study that it is possible, with adequate conditions, to adjust the charge of the membrane surface from −40 to +40 mV by...
A new pvdf ultrafiltration hollow fiber with durable performances for mbr and tertiary filtration
O. Lorain*, J.M. Espenan, I. Duchemin, Polymem SA, France
The history of the choice of the material for hollow fiber ultrafiltration fabrication is very interesting. At the beginning, in the late 1980s, cellulose acetate (CA) was chosen because it was the most hydrophilic material, ideal for the filtration with low fouling and low need for chemical cleaning. However, due to its low biological resistance and sensitivity to high pH, in the late 1990s, the use of this material declined, and it was completely replaced by polysulfone (PSU) and polyethersulfone (PES). To compensate the low hydrophilicity of these materials, the membranes were doped with hydrophilic additives like PVP during the manufacturing process. Then in the 2000s, and particularly in the United States, where the membranes market was rapidly evolving at this time, PSU and PES hollow fiber manufacturers faced problems of severe hollow fiber breakage. This was due to the use of large amount of chlorine during cleaning which degraded both the polymers backbone and the hydrophilic additives. A new fluorinated material, the polyvinylidene fluoride (PVDF), was then used to make membranes more resistant. With PVDF, the fibers no longer break, however the chlorine during chemical cleaning steps continued to degrade the hydrophilic additives causing an unexpected increase in irreversible fouling of the membranes over time. In addition, the release of the additives which are located on the surface of the pores, involved an increase in the size of the pores of the UF membrane leading also to an unexpected decrease of the rejection performances of the membranes.
Polymem with its partner Arkema have developed a new PVDF material incorporating an innovative amphiphilic di-block copolymer which is anchored in the polymer backbone during the early stages of membrane fabrication. Compared to conventional additives, this new hydrophilic polymer is not degraded by chlorine and the membrane retains its hydrophilicity throughout its service life. In addition, the pores size does not change, keeping the same rejection performances...
New PANFLUTE ultrafiltration membrane: Filtration and anti-fouling performance with complex water composed of water/oil/particles
El hadji Ibrahima Ndiaye, H. Nabet, J.-M. Pereuilh, S. Nowe, M. Jacob, Total; J.M. Espenan; Polymem SA; N. Abidine, ABC Membranes Sarl, France, J.-M. Pandraud, Clean Membranes, Inc., USA
Water plays a vital role in the production of petroleum. Producing oil or gas generates a large quantity of produced water, which is extracted with the hydrocarbons. The management of produced water is a critical challenge for operators. Produced water can be successfully reused for well injection or safely discharged to the environment, to do so, it is necessary to efficiently remove the hydrocarbons and the suspended solids. Separation processes using membrane technology have been developed to meet these challenges, but capital cost (mainly for offshore installations) and operability (fouling) remain crucial challenges.
It is well known that polyacrylonitrile (PAN) membranes have good hydrophilicity and chemical stability, but the utilization of PAN in hollow-fiber membranes has only met limited success with hydrocarbons. However, Clean Membranes developed a novel variation of the PAN polymer by grafting it with PEO to form a proprietary amphiphilic comb copolymer, polyacrylonitrile-graft-poly (ethylene oxide) (PAN-g-PEO). Hollow fiber membranes made with PAN-g-PEO were demonstrated by Clean Membranes to have exceptional capabilities for separating hydrocarbons from produced water without fouling, but these early membranes lacked sufficient mechanical strength for commercial applications. Clean Membranes subsequently collaborated with ABC Membranes and Polymem to develop and manufacture a novel in-out, multi-bore PAN-g-PEO UF membrane named PANFLUTE. Laboratory studies conducted by ABC Membranes using their proprietary PANFLUTE structural membrane design demonstrated good filtration performance in terms of wettability, permeability, and resistance to irreversible fouling with complex water composed of water/oil/particles.
Despite the success of ABC Membranes’ laboratory studies, it was understood that the expected benefits of treating oily water with PANFLUTE could best be achieved by working with a leader in the oil and gas industry, utilizing their test platforms and conducting the tests under their control. Clean Membranes, ABC Membranes, and Polymem teamed with Total to conduct this testing. This paper reports on the early data derived from these tests and the preliminary evaluation of PANFLUTE for the treatment produced water in the oil and gas industry...
Day: 09 March 2022
Time: 13:00 - 14:15 h
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Test membrane filtration and sustainable development
Prof. Dr. Pierre-Yves Pontalier, ENSIACET LCA Laboratoire de Chimie Agro-industrielle / France
Membrane processes are used in a very large number of industrial fields such as the food industry, the chemistry, the pharmaceuticals or the environment. Membrane processes contribute to the protection of the environment as they allow the depollution of industrial and urban effluents. They may also help to limit environmental degradation by integrating new cleaner processes, particularly those related to the biorefinery concept. This concept, which aims at the multivalorization of plant and animal resources, is a perfect example of the integration of membrane processes in this approach. For example, in the context of the valorization of lignocellulosic biomasses, the purification of hemicelluloses and lignins is carried out through a membrane filtration stage. Similarly, the valorization of proteins contained in wheat bran or rapeseed cake passes through an ultrafiltration stage. Another pathway that is developing is the fractionation of microalgae, called algo-refining, in which membrane processes are involved in the purification of polysaccharides and proteins.
In the case of drinking water production or industrial effluent treatment, very large membrane surfaces are used, with a lifetime of a few years. Thus, membrane processes become a very important source of pollution. The life cycle analysis of membrane processes thus shows that their impact is not negligible. Two types of impacts are generally highlighted, those related to the production of the membranes (e.g., the use of petro-sourced materials) and those related to the operation of the processes (e.g., the energy used and the chemicals during the cleaning phase). One environmental impact that is neglected is the end-of-life impact of the membranes, the fate of which poses problems. Studies are beginning to appear to evaluate methods of reusing used membranes in order to increase their lifespan, but this does not solve the problem of the end-of-life of the materials. Within the framework of sustainable development, it would be desirable to produce membranes from bio-sourced molecules and above all to facilitate their destruction...
Flow-induced deformation of filter media – Part 1: Experimental characterization and 3D simulation of the mechanical properties of filter media during perfusion
V. Puderbach*, S. Antonyuk, Technische Universität Kaiserslautern; R. Kirsch, R. Deshpande, Fraunhofer Institute for Industrial Mathematics (ITWM), Germany
Filter media made of nonwoven fibers are commonly used in multiple filtration applications especially oil and fuel filtrations. The filter medium in each case causes a specific pressure drop and the flow process applies forces on the medium. Those forces have an effect on the fibers and also the fiber bonds. Nonwoven filter media achieve their stability through the resulting fiber bonds, which can also be added by binders or additives (Petterson 1959; Backer und Petterson 1960; Ridruejo et al. 2010). Fibers and fiber bonds describe the planar structure of the material. However, not only the planar shape of the medium is relevant in the use case. Nonwovens are often used in a pleated form. So the fold causes a structural change that influences the pressure drop of the process (Grosjean et al. 2015) (Bourrous et al. 2016; Traut 2017).
This work is meant to investigate the mechanical properties of relevant liquid filter media and to use that information for the design of 3D simulations in order to make further investigations on the in-use behavior of the filter media...
Flow-induced deformation of filter media - part 2: modeling and simulation
R. Kirsch*, O. Lykhachova, Fraunhofer Institute for Industrial Mathematics (ITWM); S. Antonyuk, V. Puderbach, Technische Universität Kaiserslautern, R. Deshpande, Ruhr-Universität Bochum, Germany
The majority of simulation models for filter elements assume that the filter media are “rigid bodies”. In reality however, it is observed that the fluid flow causes deformations which can lead to well-known (and undesired) effects like pleat collapse, pleat crowding etc.
Several works were devoted to the development of models and methods to take into account this Fluid-Porous-Structure Interaction (FPSI) in order to obtain more realistic simulation results. By nature, the earlier studies focused on liquid filtration applications, of which only few are mentioned here: In , an effective permeability approach was used for an improved prediction of the relationship between pressure drop and flow rate in pleated cartridges. A coupling of flow and structural mechanics simulation based on Stokes-Brinkman equations and hyperelastic porous materials in three dimensions in space was presented in . Taber’s model for poroelastic plates was the starting point for the numerical simulation (two-dimensional in space) and experimental validation of small flow-induced deformations in . Deformations of filter media are observed in air filtration, too. In , a coupled simulation (two-dimensional in space) of the deformation of pleats in cabin air filters was studied.
The aim of the present work is to extend the applicability of the coupled simulations for liquid filtration at constant flow rates in a way that the simulations will be done in 3D, include faster flow regimes (Navier-Stokes-Brinkman) and allow for larger deformations and non-linear elasticity...
Filter modeling and simulation with GeoDict
M. Azimian*, A. Weber, A. Wiegmann, Math2Market GmbH, Germany
Several key parameters are essential as input data to precisely simulate the filtration characteristics of a filter element at macro scale, e.g. simulating the particles filtration through a whole filter with housing, as shown in Fig. 1. Flow conditions, simulation stop criterion, the fluid and particles characteristics, as well as input parameters related to the micro-structure of the media, should be defined. The main input parameters for the macro-scale simulation, which are related to the micro-structure of the media, are: permeability of the media, maximum particle packing density and maximum flow resistivity for both the depth filtration regime and cake filtration regime (four parameters), and also the fractional filtration efficiencies. These parameters are routinely obtained by flat sheet experiments through the filter media. However, the GeoDict software, a pioneer modeling and simulation tool can be applied to obtain these input parameters, thus reducing the need for the time-consuming and costly experimental tests.
The study of the micro-structure of the filter media is the starting point to understand, analyze, and optimize a filter. The first simulation step on the media scale (here woven media) consists of modeling the micro-structure of the woven media using WeaveGeo module of GeoDict...
Performance evaluation of engine intake air filter media coated with Nylon-66 nanofibers
J. Johnson*, M. Muzwar, K.A. Prakasha, R. Chetty, Indian Institute of Technology Madras, India
Air filtration plays a vital role in the performance and operations of heavy-duty vehicles. The supply of clean air into all engines is critical to their performance. A good air filter supports the engine operation by ensuring that the air entering the system is clean and free of grit and dust. Fibre diameter and pore size are the two critical parameters that significantly affect the media's filtration performance and dust deposition. Nanofibers are typically fibres with less than 1 μm, and the nanofiber-coated filter media offers higher filtration performance than the conventional filters. Adding nanofibers also extends the life of the filter by making it easier to clean because the fibres keep the particulate at the surface rather than depth loading. In this study, Nylon 66 nanofibers were coated over a cellulose based conventional filter media using electrospinning and the performance of the coated media were evaluated in terms of filtration efficiency, dust holding capacity, quality factor (Q-factor), etc. The filtration performance...
CFD simulation of open-cell polyurethane foams using Kelvin model
H.J. Parekh*, G.G. Garkhedkar, S.M. Chakote, Varroc Polymers Pvt Ltd, India
Polyurethane (PU) foam has a wide variety of applications in various industries such as automobiles, textile, chemical, foundry etc. This paper focusses on the filtration application, of PU foam, used to supply clean-air in (2W) motorcycle engine. Oil impregnated PU foam is widely used in the two-wheelers motorcycle industry in India and other African countries. The oil-impregnated filter foam, in the times of ultra-high performance filter media (cellulose and non-woven filter media), is used because they are in-expensive, cleaned, re-oiled and re-used again and again. Also, as PU foam are compressible in nature, they don’t require extra special sealing material around periphery. Such an open-cell PU foam is often characterized by the unit PPI (Pores-Per-Inch). PPI of the filter foam directly affects the pressure drop of the air intake system and more importantly its filtration efficiency. Engine Air filter assembly pressure restriction has direct impact on the performance of an engine motorcycle (fuel economy, exhaust emissions, power deliver etc.) Therefore, it is crucial to predict & control the airflow resistance of such an open-cell PU foam.
This study focuses on the pressure drop prediction of dry (without oil impregnation) foam through CFD (Computational Fluid Dynamics). The aim is to predict the initial pressure drop of (open-cell) PU foam filters used in Indian motorcycle engine air filters...
Comparative presentation of a filter element test according to EN 15695-2 using monodisperse aerosols classified by aerodynamic diameter
D. Keßlau*, Institute of Air Handling and Refrigeration (ILK), Germany
Microfiber disc filter for water & wastewater treatment
S. Choi*, G. Kim, Digiwatec; Y. Kim, Hanyang University; K. Koh, CtoC; S. Kim, EE Company, Korea
Materials such as plastic, cotton, fiberglass, wool, and paper have been widely applied as economical and effective filter materials in the field of water purification and water treatment in the form of cartridge filters. In addition, plastic-based fiber materials are applied to filter devices in the form of media and filter yarns, because they have better filtration performance than conventional filter media such as sand, but have a narrow installation area and a feature of backwashing.
In this study, a plastic microfiber material was used to form a circular disk and utilized not only the excellent filtration characteristics of the microfiber fibers, but also the excellent cleaning characteristics of the circular disk structure.
A filter in which tens of microfiber circular disk filters were stacked was subjected to a performance comparison test with a cartridge filter and a media filter. It was confirmed that the microfiber disk filter can control the filtration performance through changes in the filtration thickness and filtration speed of the filter, and form a turbulent flow between the disks, thereby providing excellent backwash performance. The multi-array structure in which tens of microfiber disk filters with smaller and larger diameter are arranged alternately is intended to improve filtration and backwash performance. Through conducting the optimization and field performance tests with the various water qualities, we plan to commercialize the microfiber disc filter as the 1st stage filter before membrane filtration or media filtration system, the safety filter before RO membrane, the fiber media filter in the wastewater system, etc....
How programmable materials can be used to design woven filter media with optimized backwashing properties
R. Kirsch, S. Osterroth, S. Rief*, Fraunhofer Institute for Industrial Mathematics (ITWM), Germany
Global challenges such as sustainable development, climate change, renewable energy, or individual mobility increase the necessity for a much more efficient and sustainable use of our resources. Programmable materials have the potential to initiate a paradigm shift since they can perform system functions through their internal design. This allows for increased functional integration while simultaneously reducing system complexity. Programmable materials are materials whose inner structure is designed and manufactured in such a way that properties and behavior can be controlled and reversibly changed by external stimuli, e.g. temperature changes or chemical agents. Moreover, new manufacturing methods make it possible to specifically produce these structures in the micrometer range. These methods include for example, additive processes like 3D-printing.
In this paper, the focus is on the use of programmable materials in the area of effective filter cleaning. More precisely, we investigate weaves in a liquid filtration application. In the regular filtration step, it is desirable to have high filtration efficiencies, a low pressure drop and a high dust holding capacity. Low pressure corresponds to energy savings and low operating costs. The dust holding capacity ensures efficient use of operational capacity. When certain limits are reached, the backwashing step is performed to clean the filter medium from deposited dust. Thereby, the filter medium does not need to be replaced and maybe used several filtration cycles. However, backwashing cannot clean the medium entirely and the motivating question is: What is the potential to improve the backwashing efficiency by geometrical changes of the filter medium using programmable materials? Backwashing efficiency means short regeneration time, low clean water consumption and minimal particulate residues. We answer the above question by...
Removal of very fine suspended solid particles with mechanically self-cleaning filter from hot rolling mill cooling water
S. Gluck, Sofi Filtration Ltd, USA; V. Hakala*, S. Pandey*, Sofi Filtration Ltd, Finland
Water resource management is a key sustainability challenge for steelmakers in order to improve the production cycle as the water scarcity grows. Water is used extensively in the steel industry for cooling process for e.g. continuous casting or hot rolling. In the hot rolling mills filtration is required to remove the suspended particles that remain in the water following the decantation process. To maintain the efficiency of the production cycle as well as to protect the operational environment from corrosion and microbial growth, cost-effective fine particle filtration is required to efficiently remove suspended solids contaminants build up.
Herein, Sofi Filtration conducted a pilot study as part of the WHAM EU project. In this pilot operation Sofi's technology was tested against sand filter technology in an Italian steel mill. A research study was carried out for a cooling water of a hot rolling mill by feeding both technologies with the same water in conjunction and sampling for the Total Suspended Solids. The effluent from a hot rolling mill contains oil and other compounds containing elements such as iron, copper, boron, and manganese.
The pilot operation result shows that...
14.45h - Coffee Break
Day: 09 March 2022
Time: 14:45 - 16:00 h
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Inorganic membranes made of sintered clay for the treatment of biologically modified water
J. Bentama*, Sidi Mohamed Ben Abdellah University, Morocco
It is now commonly believed that membrane crossflow filtration processes can be considered as high performance separation techniques, not only in laboratory experiments but also for many industrial applications. The present work aims to describe and characterize inorganic membranes at low cost and to study their performance through a fermentation–crossflow microfiltration (MF) coupling process. New mineral membranes were created from sintered clay in which a certain quantity of coal was added to the mixture before the sintering operation in order to increase and control the membrane porosity.
Previous works have shown that these low-cost membranes can be used as MF membranes for surface water clarification. Crossflow MF of a biological fluid model was performed in a membrane bioreactor. In this technique the cell culture was continuous. This allowed us to control the environment of cells and to obtain very high active concentrations by the recycling of the microorganisms. The biological fluid model used in different operations of MF was a suspension of yeast. Periodic back-flushing coupled with chemical cleaning was done without isolating the membrane from the filtration module. Experiments of characterization of the fouling state of the membrane after a certain time of operation were started using an acoustic technique. The results are promising...
Ceramic membrane technology for efficient separation of chemical degraded lignosulfonates and target products
M. Ebrahimi, F. Boruta*, A. M. Oestreich, C. Lin, P. Rinn, Schmitz, P. Czermak, University of Applied Sciences Mittelhessen; F. Ehlen, Justus Liebig University Giessen, S. Schütz, MANN+HUMMEL GmbH, Germany
The ongoing discussion about a necessary reduction of CO2-emissions and depleted reservoirs of crude oil worldwide lead to an increasing interest in sustainable, renewable and alternative sources for aromatic molecules. In this context, lignin-containing process streams are in focus of several research programs as lignin is the most abundant renewable source of aromatic molecules on earth. The pulp and paper industry e.g. produces ca. 50 million tons of lignin per year, but only 2% are used for production of industrial products, the rest is incinerated for internal energy supply.
In this work, a membrane based separation process for chemically degraded lignosulfonates is investigated. For the separation of desired products from partly degraded lignosulfonates (PDL) ceramic ultrafiltration membranes were examined. The influence of relevant process parameters on separation efficiency, permeate flux and fouling effects strategies is part of this research work...
Perfusion bioreactor with integrated dynamic crossflow filter
G. Grim*, ANDRITZ Separation GmbH, Germany
Continuous manufacturing plays a growing role at chemical and biological processing. Also for bioreactions, the advantages meanwhile are common knowledge. Higher cell densities can be achieved, even the cell culturing can be done continuous, sensitive and unstable proteins can be removed.
In fermenters, it is easy to add e.g. new nutrition. But removing the metabolism product and eventually the target protein is the challenge. To achieve a constant process volume and steady state process a separation process is required. State of the art is, that a crossflow filter is installed next to the bioreactor and the retentate with the cells is pumped in and out of the bioreactor.
The full benefits of this idea can be utilized, if the crossflow filter is mounted directly into the process chamber of the bioreactor. This is possible, if the crossflow system does not need a pumping of the retentate. The Krauss-Maffei Dynamic Crossflow Filter is the optimum technology to realize this combination of two process steps within one unit, since no pump, piping, or instrument is required at the retentate side of the technology. The rotation of the filter membrane is causing the crossflow effect. At the same time, the filter membrane cleans it’s surface, but also is causing the required mixing effect in the bioreactor and avoids sedimentation.
The size of the filtration surface is selected, so that approx. 10% of the fermenter volume can be filtered per hour. Depending on growth rates, a constant or fluctuating harvest flow rate can be adjusted. By correct selection of the pore size of the installed membrane, it can be decided, if the target protein will remain inside of the bioreactor or will be removed together with the metabolism products.
In case the protein is instable or sensitive, microfiltration will be selected, so that it will be constantly harvested from the bioreactor. Isolation and purification can be done in parallel to the bioreaction process. Optimum is...
Meltspinning and post-treatment of gas separating hollow fibers from poly(4-methyl-1-pentene)
M. Pelzer*, T. Gries, RWTH Aachen University, Germany; M. Shalygin, S. Markova, V. Teplyakov, A.V. Topchiev Institute of Petrochemical Synthesis, Russia
There is a need to create targeted membranes designed for specific practical problems such as the separation of hydrogen sulfide from oil and accompanying gas, the separation of CO2 from different process streams or the conditioning of biogas. These processes require integrated membrane systems possessing stability of membrane material under the process conditions. Due to its outstanding chemical resistance, good mechanics and stability at the presence of different organic compounds (including C3+ hydrocarbons), poly(4-methyl-1-pentene) (PMP) is suitable for the use in the mentioned petrochemical separation processes. The scope of this work is the production of hollow fiber (HF) membranes from the semicrystalline PMP via the environmental friendly melt spinning process and the corresponding permeation performance in a membrane module for gas separation...
Production of nanofibers for filtration applications via solution electrospinning: Approaches of industrial scale production
T. Schneiders*, T. Gries, RWTH Aachen University, Germany
Nanofibers and submicronfibers, as a textile structure in the form of a nonwoven fabric, show excellent properties for applications such as tissue engineering, drug delivery in medical products, filtration, catalysis but also technical textiles and protective clothing. These properties include a high specific surface area, interconnected pores and adjustable pore sizes on the nanoscale. Several technologies are used and developed to produce fibers with a diameter below one micrometer. Most processes have either a high investment and operating cost and are limited to few polymers or material combinations like phase separation and melt blowing or produce wide spread and non-uniform fiber diameters like flash spinning.1,2 Solution electrospinning is considered a viable method to produce nanoscale fibers due to its simplicity, cost efficiency and material compatibility.
As solution electrospinning so far was used for small scale production and applications, a major challenge for the use in filtration and industrial scale production is the upscaling of nanofiber production while staying competitive to other technologies. Within solution electrospinning there are several approaches that demonstrate the possibility for upscaling or first results in industrial production. Needle based and open surface technologies pursue different innovations and ways to reach a higher output of nanofiber materials. A short overview of different solution electrospinning technologies and their challenges facing upscaling as well as the benefit for the filtration market will be given in this presentation...
Microfiltration membranes based on nonwoven materials for particle separation
E. Boyraz*, F. Yalcinkaya, I. Gallus, J. Maryska, Technical University of Liberec, Czech Republic
The existing water resources in the world are decreasing nowadays due to domestic, agricultural, industrial and similar wastes. Therefore, the treatment of wastewater is important for our present and future. The membrane process (microfiltration and ultrafiltration), chemical destabilization (conventional coagulation) and electrochemical destabilization (electrocoagulation) are the most common processes for the wastewater filtration. Non-woven materials are commonly used in the decontamination process for the particle separation removal larger than 1 µm.
Non-woven materials have randomly oriented fibers creating pores that the fluid can flow through. They have many advantages that can be controllable such as pore size, the density of fibers and design. They are also cheap material for the water filtration. In this work, the non-woven membranes were prepared and they have been used for the particle separation. The performance of non-woven membranes such as flux, and the relationship between pore size, air permeability, and lamination process were investigated...
Effect of spacer on heat and mass transfer in direct contact membrane distillation
Y. Taamneh*, Jordan University of Science and Technology, Jordan
Membrane Distillation (MD) has become a prominent technology for desalination. It differs from other membrane technologies in that the driving force for desalination is the difference in vapour pressure of water across the membrane, rather than total pressure. One of the most probably critical problems facing this technology is known as temperature polarization (TP) phenomena. This phenomenon occurs because the membrane surface temperatures always contrast with bulk temperatures. It may lead to a considerable loss of the thermal driving force and lower rates of mass transfer.
Hence, to reduce the concentration polarization effect in many membranes application, enhancing the shear rate near the membrane as well as eddy generating is always needed. Many researchers have come up with a solution of using frame-like turbulence promoter in various MD modules to augment the mass flux and minimize the polarization effect across the membrane. Many research groups have utilizing CFD techniques to gain a deeper understanding of what taking place inside membrane modules, to put up the optimum design process and modulate the performance of MD modules.
This study was intended to develop the heat transfer correlation for the spacer-filled channels using experimental and numerical results presented in a previous paper by the same author. Computational fluid dynamics (CFD) simulations...
New generation of filter media for ePM1 applications
A. Baderschneider*, A. Seeberger, IREMA-Filter GmbH, Germany
In the last years, the demand for better air quality has continuously increased. Especially indoor air quality IAQ is of concern and reliable filtration solutions are more important than ever to provide a safe and healthy environment in occupied buildings. Therefore, tailored filter media with an enhanced filtration efficiency for HVAC (heating, ventilation, air conditioning) applications is required. At the same time, it is needed to focus on energy conservation, which is favorable for the environment and additionally reduces the energy costs. To decrease the energy consumption of HVAC units, the filter media needs to have a low pressure drop during its complete time of usage. Based on those requirements, IREMA-Filter has set the goal to develop a new generation of pleatable filter media that combines a high filtration efficiency with a decreased pressure drop.
The filters that are made with the new media are tested and described by DIN EN ISO 16890. This standard categorizes HVAC filters depending on the fractional efficiency for aerosol removal during testing. ePM1 results are reported for aerosol (DEHS) that has an aerodynamic diameter of 1 µm and less. This particle size range is of major concern due to its negative effects on human health.
During the test for DIN EN ISO 16890 a filter’s performance is tested twice, under initial conditions (new filter) as well as after an isopropyl alcohol (IPA) vapor treatment which removes all of the electrostatic charges within the material. After this discharge step the filter can pass the ePM1 test successfully, if its minimum efficiency is at least 50% regarding aerosol diameters smaller than 1 µm (0,3-1,0 µm). Previously the mechanical efficiency (after discharge) that was needed to pass this requirement generally was linked to a high pressure drop of the filter.
IREMA-Filter developed an enhanced type of synthetic filter material that combines high initial efficiency with high mechanical efficiency while keeping the pressure drop low due to its unique integrated prefilter fiber design. Based on this innovation a new generation of synthetic filter media for ePM1 applications is achieved with an extended service life and improved energy consumption footprint. The following table shows...
Development of an efficient hybrid filter media for removal of microplastics from wastewater
L. Weiter*, J. K. Duchowski, HYDAC FluidCareCenter GmbH , Germany; S. Leyer, University of Luxembourg, Luxemburg
The dramatic increase in water consumption on the one hand and plastic production and use on the other hand have resulted in a combined issue of microplastic contamination spread throughout the multiple water sources and points of use. Although most of the plastic products are designed for short use, they exhibit long lifespans. Because these materials do not decompose biological degradation, their existence in the environment may extend for hundreds of years. Moreover, through the mechanical friction and abrasion processes, the original relatively large items, such as bottles, can get ground down to the small particulate size well into the micrometer and even sub-micrometer size range. The extremely small size of these particles makes them invisible to the naked eye and therefore difficult to detect and/or remove. In order to address these issues, a considerable amount of effort in several past years has been devoted to the improvement of the detection methods as well as the means of removal and/or recovery of these cumbersome materials.
A natural point for the concentration of these efforts is at the point of treatment of the wastewater streams. However, in contrast to the retention of large particulate that can be removed by screens or sieves, the retention of the micro particulate materials presents a much greater challenge. Because the wastewater treatment plants process 100s of liters per hour, the application of nano or micro filters is difficult if not impossible. The huge amount of micro particulate would lead to a nearly immediate blockage of the porous structure making the process not viable in practice. Therefore, the intent of the project is to develop a new hybrid filter media that contains a modified fiber matrix. The new material should exhibit enhanced filtration efficiencies without the penalty of high-pressure drops. The first stage of the project will include microplastic contaminant analysis in sewage water samples. The second step will consist of preparation of the modified materials and the evaluation of their performance characteristic. The filter setup performance will be...
Filter screen from permeable matrix of pressed metal wire and its properties
I.S. Pyatov, L.V. Vorobeva, A.N. Korchagin, I.V. Kirpichev, K.N. Petrunina*, REAM-RTI, LLC; V.N. Ivanovsky, A.V. Bulat, Gubkin National University of Oil and Gas, Russia
REAM-RTI, LLC introduce an innovative permeable matrix of pressed metal wire (PM), products from which are patented and used for filtration of liquids and gases. The manufacturing technology complies with modern ISO: 9001 standards and allows the manufacture of filter elements with a filtration rating up 5 to 500 microns with various geometry and sizes. The material is a wire structure that, as a result of cold pressing, forms an openly porous and elastic system permeable in all directions.
2. Low hydraulic resistance due to the use of round wire provides:
- high erosion resistance;
- high ratio of the area of the slots channels passing the filtered medium to the total area of the filter surface.
3. The possibility of manufacturing a filtering screen from various materials allows....
Dosing of hygroscopic salt particles for influencing the operating behavior of surface filters for dust separation
D. Horst*, Q. Zhang, E. Schmidt, University of Wuppertal, Germany
When separating dusts with surface filters, the structure of the dust cake that forms in the process is of great importance, as it has a decisive influence on the operating behavior of the filter. With regard to the cyclic regeneration of the filter, the mechanical strength of the dust cake is particularly relevant, which in turn can be influenced by so-called raw gas conditioning. The adhesive forces of the particle contacts have a considerable influence on the mechanical strength of the dust cake. An increased mechanical strength in turn improves the cyclic regeneration of the filter, resulting in sufficient removal of the dust cake from the filter medium with less energy input.
In any dust cake of non-hygroscopic particles, the metered addition of a fraction of hygroscopic salt particles offers a possibility to influence the operating behavior of surface filters. For this purpose, a temporary change in gas humidity induces the deliquescence and efflorescence of the added salt particles. In this case, the deliquescence and efflorescence properties of hygroscopic salt particles are used to subsequently change the adhesive forces of the particle contacts as well as the structure of the dust cake formed on the filter medium and thus influence the operating behavior of the filter.
In the present paper experimental investigations on the influence of the concept on the operating behavior of test filters, especially with regard to the regeneration of the filter, are presented...
Precoating: influence of moisture and thickness on collection efficiency
B.K.S.A. Andrade*, M.L. Aguiar, Federal University of São Carlos; R. Sartim, ArcelorMittal Global R&D, Brazil
Precoating consists of covering filter media with particulate material forming an initial powder layer which is responsible for reaching the clogging point. The particulate matter accumulates in the fibers and in the particles already captured, forming the dendrites, and then the cake. Consequently, it increases the efficiency of dust collection at the beginning of filtration, guarantees the passage of air flow freely through the bag, promoting better detachment of the cake while extending its life span. In order to analyze the influence of moisture and precoating layer thickness on the collection efficiency for micrometric particles, were performed filtrations following the VDI 3926 Standard. Initially, the characterization of the particulate material was carried out to obtain the aerodynamic diameter, the average volumetric diameter, the chemistry composition and images in a Scanning Electron Microscope (SEM). Then, the filter medium was characterized to obtain the fiber diameter, porosity and permeability. Then, an experimental design was made, varying the conditions of humidity (5, 10 and 15%) and thickness according to the limit pressure drop (50, 100, 150, 200, 300 e 400 Pa). Precoating was carried out to the desired thickness by feeding the particulate material with the specified humidity. Then, primary sintering powder was fed to evaluate the collection efficiency...
Correlation between clogging point and precoat to obtain high collection efficiency in bag filters
B. Râmela de Melo, C.R. de Lacerda*, B.J. Chiaramonte de Castro, M.L. Aguiar, Federal University of Sao Carlos, R. Sartim, ArcelorMittal Global R&D, Brazil
Mostly virgin filter media have low collection efficiency, which requires superficial treatments to obtain a better performance. One of these treatments is coating filters with PTFE membrane. However, surface treatment increases the pressure drop and its cost, and consequently also increases the cost of equipment maintenance and operation. Another alternative commonly used in the industry is precoating, which is less expensive and has good performance in terms of filtration efficiency, but there are few studies on this subject. Other advantages of precoating are the lower initial filter media pressure drop, the possibility of increasing the useful life of the filter bag, and can also contributes to the chemisorption of pollutants present in the gas, such as HCl and SO2. For the efficient use of this technique, it is necessary to know the ideal mass of precoat material that guarantees high filtration efficiency. In the present work we evaluated the necessary mass of precoating material to be used and its correlation with the clogging point.
The grade collection efficiencies for micro and nanoparticles were analyzed for different masses of limestone precoat deposited on the polyester filter medium (PE), in which, one of them was the mass obtained by the clogging point. Also a polyester filter medium with PTFE membrane (PE/PTFE) was used to compare the results. The clogging point, obtained by...
Upgrade of existing kiln/raw mill bag filter optimising technology and performances
M. Colombo*, M. Rovetta, D. Bacco, M. Recalcati, CTP Team S.r.l., Italy
The concept of optimisation is considered one of the keyways of permanently resolving issues impacting OPEX and helping a business be sustainable. This study shows how measure the gap between the present and optimised operation levels of a dust collector system and decide on how convenient it is to proceed given existing conditions by focussing on particular areas of expertise – performances, reliability of technology, quality and savings.
In this case study, the existing dust collectors on kiln / raw mill of the cement plant are not performing according to the design conditions, the initial guaranteed value of pressure drop is always exceeded inevitably leading to the main following conditions:
Some examples of the criticalities highlighted by a preliminary analyse were related to the internal filter design, the exit available area reduced, the bottom, vertical and lateral gas velocity. Rendering the existing filter with a 3D model suitable for running a CFD simulation combined with a tailored process data collection campaign, allow both to perform a detailed gas behave analysis and rectify the mechanical criticalities affecting the equipment performances. This novel “OTP OPTIMISE PERFOMANCESR” approach passes through the deep process analysis and equipment validation and the study of a comprehensive solution to optimize the existing bagfilter with low impact modifications and saving capex.
The main results have been...
Synergistic effect between electrostatic precipitation and fabric filtration of nanoparticles
B.J.C. de Castro; C.R. de Lacerda; B.R. de Melo; M.L. Aguiar*, Federal University of São Carlos; R. Sartim, ArcelorMittal Global R&D, Brazil
Exposure to nanoparticles offers a great risk to human health, since, once inhaled, they can reach the bronchioles and alveoli and pass into the bloodstream, being then transported throughout the body. Several serious illnesses have been related to the inhalation of air polluted with nanoparticles, such as vascular disfunctions and permanent damages to the central nervous system. One of the promising alternatives for controlling particulate emission by industries is the hybrid filter, which combines electrostatic precipitation and fabric filtration in a single device. Even though good results have been obtained and reported for the collection of microparticles, there are few studies in the literature that assessed the performance of hybrid filters for nanoparticles. The purpose of this study was to address the question of whether the synergistic effect previously observed for larger particles in hybrid filters is also evidenced for nanoparticles, with diameters in the size range of 10-300 nm. A bench scale hybrid filter...
Nanoparticle filtration from table 3D printers using hollow-fiber membranes
P. Bulejko*, K. Mayerová, O. Krištof, A. Zatočilová, Brno University of Technology, Czech Republic
Applied geometry optimization of a novel 3D-printed wet-scrubber nozzle with Lattice Boltzmann methods
F. Reinke*, J. Meyer, A. Dittler, Karlsruhe Institute of Technology (KIT); M. Novosel, ESTA Apparatebau GmbH & Co. KG, Germany
In the course of progress in metal cutting processes (grinding, brushing, polishing), increasingly fine metal particles are produced. The separation of these particles is becoming more complex. Particularly in the case of submicron particles (mainly PM1 and PM2.5 fraction), downstream filter elements are required, which are associated with an additional pressure loss of the overall system. For this reason, new technologies with high particle separation efficiency and minimal energy input are required. One possibility can be wet-separation processes with innovative 3D-printed nozzle geometries for dispersion of the washing liquid. Since the dispersed washing fluid captures the particles, a fundamental understanding of the prevailing flow conditions is necessary. Here, numerical flow simulations can support the development in many steps of the product development cycle. Enabling pre-manufacturing studies for various designs, represents one major benefit of such an approach. Due to the degrees of freedom in terms of the geometry shapes by using rapid prototyping technology, the simulation is able to assist with the selection of design choices by predicting relevant physical properties. On the one hand, it therefore expands the overall range of possible design studies and on the other hand, reduces the amount of physical testing and premature manufacturing steps e.g. printing. This results in a reduction of time and cost in the whole development cycle.
In this contribution, an applied numerical geometry optimization with several design studies of an innovative 3D-printed wet-scrubber nozzle is presented...
Influence of pulse jet cleaning interval on the effective filtration area of a pleated filter in the plug-in type dust collector
K. Fukui*, T. Narita, K. Furumoto, T. Fukasawa, T. Ishigami, Hiroshima University, Japan
Pulse-jet plug-in type compact dust collectors remove dust from the gases generated in factories. A pleated filter is widely used in this device because the filter media is folded in a pleated shape to increase the filtration area. In order to operate this device continuously, the dust particles deposited on the filter should be removed from the filter. However, since some dust particles accumulate inside the filter and form a thin layer (the primary adhesion layer) which cannot be removed, the performance of the dust collector changes with operation time.
Therefore, in this study, the effect of the pulse jet cleaning interval on the deposition state of the dust particles on the filter was analyzed and it was also aimed to develop the evaluation method for the dust collection performance...
ISO ePM1 60 % grade type filter (F7) behavior in a building with air recirculation
V. Silvonen*, L. Salo, T. Raunima, P. Karjalainen, T. Rönkkö, Tampere University; I. Kulmala, VTT Technical Research Centre of Finland Ltd, Finalnd
Mechanically ventilated buildings use filtration to remove particles from supply air. In cases without recirculation, the concentration of particles in the supply air is simply the outdoor concentration multiplied by the filter penetration. However, some building ventilation systems partially recirculate exhaust air to reduce energy consumption and, to some extent, lessen particle loading on the filters. Under these circumstances the indoor air concentration is more difficult to estimate. Here, we present a case study from measurements in an office building, where the average recirculation ratio was measured as 0.6. The efficiency of the filter is compared to the true particle penetration when air is recirculated, showing...
Improvement of air filtration performance using patterned nanofibrous membrane
Yufeng Liu*, Zhongli Ji, China University of Petroleum, China
Nanofibrous filter has a very wide range of applications in the removal of particulate matter in the air and the prevention of disease aerosol transmission because of its fine diameters and high specific surface areas. Using a denser nanofibrous structure or finer nanofiber diameters is a common approach to improve its filtration efficiency, but usually results in a striking increase of air resistance, which means high energy consumption and more likely to be blocked. Here, we have shown a novel nanofibrous composite filter that combined two layers of staggered patterned nanofibrous membranes which could improve the filtration performance due to its non-uniform packing density distribution. Electrospinning was employed to fabricate patterned nanofibrous membranes with different parameters on non-woven fabric. The air resistance and the particle penetration rate of the dual-layer staggered filter were reduced to...
Highly efficient electrospun recyclable pet nanofibers for airborne filtration and disease prevention
K. Machry, D. Bonfim, M. L. Aguiar*, A. Bernardo, Federal University of São Carlos, Brazil
Electrospinning techniques have been explored in the last years due to the high efficiency of particle collection. The population increase of the last decades contributed to global pollution, such as the emission of harmful materials into the environment. The rapid consumption and discard of PET derivatives, such as soda and water bottles, is a topic of growing concern due to the high volume of waste in the oceans and the lower decomposition of this thermoplastic. A way to reduce the global waste of PET is to recycle and give another destiny for plastic. The objective of the present work is to develop a highly efficient recycled PET filter for airborne filtration by electrospinning...
Investigation of accumulation of particles into ﬁbrous ﬁlters using x-ray tomography and flow simulations
J. Virkajärvi, A. Koponen*, T. Turpeinen, VTT Technical Research Centre of Finland Ltd., Finland
Fibrous ﬁlters are commonly used to separate suspended particles from air. Cellulose was previously a commonly used raw material in air filters. Presently fibrous filters are made either from plastic or glass fibres, but it would be environmentally important if one could replace them at least partly with more environmentally friendly and healthy fibres.
In this study we made generic test filters with a mixture of viscose fibres (0.5 dtex, length 5 mm, diameter 6 um) and either softwood pulp (30% of weight, KP1) or nanocellulosic fibres (10% of weight, KP2). The sample properties were: thickness 3 mm, the basis weight 200 g/m2 and porosity 95%.
The samples were made using foam laying . Foam enables the use of higher fiber consistencies with wood fibers and mixes of staple and wood fibers than the traditional nonwoven techniques.
Pressure drop and capture efﬁciency are the most important parameters for assessing the performance of these filter. The filtration efficiency was measured using the ISO16890 procedure. Both samples had similar pressure loss and capture efficiency. Their capturing performance was similar to typical EU5 filters with a two times higher pressure loss...
Influence of stitching holes in the clogging point and filtration efficiency of a filter medium
C.R. de Lacerda*, B. J. Chiaramonte de Castro, B. Ramela de Melo, M. L. Aguiar, Federal University of São Carlos; R. Sartim, ArcelorMittal Global R&D, Brazil
Seams are commonly used during the manufacturing of filter bags to ensure the cylindrical design. However, the seam may influence the filtration performance due to the presence of stitching holes. In the initial moments of filtration, more specifically in the first filtration cycle, the filter pores are filled with particles, however at that moment the stitching holes can cause preferential paths to the airflow and thus, changing the clogging point behavior. The issue of seam has been discussed in the literature from the perspective of emissions but there are few works concerning the influence of seam in clogging point of the filter media. The aims of this work were to investigate the influence of stitching holes in the clogging point behavior and to evaluate the filtration performance of microparticles using a filter material of an aromatic polyimide (PI) and polytetrafluorethylene (PTFE) scrim...
Formation and rearrangement behaviour of ash particles in diesel particulate filters
M. Kaul*, E. Schmidt, University of Wuppertal, Germany
Diesel particulate filter (DPF) are used for exhaust aftertreatment in passenger cars and commercial vehicles. The particles to be separated are primarily carbon-based components formed in the engine compartment due to incomplete combustion. The aftertreatment converts those components into ash particles.
The particle-formation inside the DPF has an impact on the filtration device´s operating performance, e.g. the separation and the backpressure behaviour. Three different kinds of particle formation can be differentiated as shown in figure: The layer formation, the filling at the end of the channel, and a blocking at the front side of the channel.
At the Institute of Particle Technology of the University of Wuppertal, a wind tunnel with a DPF unit brick has been built to study the storage and rearrangement processes inside the channels...
Conceptional design for fractional filtration efficiency testing of gasoline particle filters (GPF)
D. Göhler*, C. Rupf, S. Große, C. Peters, A. Rudolph, Topas GmbH, Germany
Gasoline particle filters (GPFs) are gaining an increasing importance since regulations for engine particle emissions become more and more strict not only for diesel engines (Joshi & Johnson 2018). Thus, high effort was spent in the recent years on the development of GPFs (Lambert et al. 2017). But the current state of the art regarding production control related to particle removal efficiency is claimed to be not satisfying (e.g.: test time, GPF loading).
To fill this gap, a comprehensive testing program was performed by means of an approved production control test system (AFC 132 QC HEPA, Topas GmbH, Germany) that permits a complete particle separation efficiency testing in 30 s. On the basis of several GPF specimens with quite different separation efficiencies, a comprehensive testing program was performed using quasi-monodisperse and polydisperse, metastable reference aerosols composed either of liquid or solid (see Fig. 1) particles. Separation efficiencies were characterised by contemporaneous analyses of upstream and downstream aerosol. For this purpose, different aerosol-analytical instruments/methods like condensation particle counters, optical particle counters or optical particle size spectrometers were operated. Moreover, separation efficiencies of quasi-monodisperse aerosols were cross-checked with fractional separation efficiencies based on polydisperse test aerosols and differential electrical mobility analysis.
Received data are promising and allow....
Morphology of deposits on single fibres build by deposition of aerosol particles in the diffusion and interception regime
J. Zoller*, J. Meyer, A. Dittler, Karlsruhe Institute of Technology (KIT), Germany
The morphology of particulate structures build on single filter fibres due to exposure to aerosol is not reported experimentally for particles smaller 360 nm in literature, although common particles from exhaust gases are in this size range.
This study investigates the morphology of deposits build on a 40 μm single fibre exposed to propane soot (157 – 238 nm count median diameter) or aerosol generated by spark discharge between carbon electrodes (68 – 134 nm count median diameter). The fibre was positioned perpendicular to the flow and the flow range was 6 – 57 cm/s. The figure shows...
Hot gas filtration for the recovery of heavy metal-reduced ashes from sewage sludge incineration
L.F. Köhl*, U. Petasch, J. Adler, M. Lincke, B. Faßauer, A. Michaelis, Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Germany
Ashes from sewage sludge incineration contain phosphorus which is a vital and irreplaceable nutrient and is used as a fertiliser in agriculture. Due to the chemical composition of the phosphorus compounds and the excessive content of heavy metals, sewage sludge ashes do not fulfil the requirements for direct use as fertiliser in agriculture. To be able to use the ashes, they must be reduced of heavy metals. In recent years various chemical and thermal processes have been developed. Thermochemical processes are used for phosphorus recovery from sewage sludge ashes in which the desired substance conversions can be achieved by reacting the ashes with special additives. This technique is exclusively carried out in downstream process steps that are completely decoupled from the actual sewage sludge incineration but uses reaction temperatures of 800 – 1000 °C, which are in the range of the of the temperatures of the incineration process. Energetically advantageous would be processes which directly utilise the thermal energy in the incineration process to modify the ashes and, by fractionating the reaction products via hot gas filtration, enable the production of ash fractions suitable for use as fertiliser. However, the combination of hot gas filtration and thermochemical conversion is not yet a sufficiently researched process and can lead to considerable stress on the filter material.
In this work, the novel procedure with its technological challenges will be introduced and the advantages and disadvantages will be presented. Special focus will be placed on the hot gas filter, which are exposed to particularly high loads due to the new process...
Improvement of dust release functions on the basis of single particle investigations
N. Schwindt, G. Reznik*, M. Kaul, E.Schmidt, University of Wuppertal; D. Schulz, H. Kruggel-Emden, Technical University Berlin, Germany
Dust emissions result from the handling of bulk solids in production processes. These emissions can lead to environmental pollution, long-term diseases or cause explosive atmospheres. In order to reduce all this kind of possible hazards for the environment and humans prediction methods of dust emissions determining the dust mass reliable during a process step have to be developed.
In order to improve the dust release functions gained in a previous project collaboration between the Institute of Particle Technology (University of Wuppertal) and the Department of Mechanical Process Engineering and Solids Processing (Technische Universität Berlin) further investigations on an experimental and numerical level are carried out. Here, the first parts of the experimental studies are presented which are achieved by the Institute of Particle Technology. In contrast to previous investigations now experiments with single particles, which derive from a so-called Rerefence Test Bulk Material (RTBM), are performed. The RTBM is a blend of spheres and a well-defined powder in which the powder represents the fine material and the spheres act as the coarse material. The aim of the focus on single particles is to gain more detailed information about the impact factors of the release of fine particles (powder) from a surface (spheres) in dependency of physical parameters...
Concept for the simultaneous release and separation of dust by means of electrostatically assisted spray nozzle systems
M. Weidemann*, E. Schmidt, University of Wuppertal,Germany
The use of various raw materials in the form of bulk material takes place in the building materials industry, agriculture and the food industry, among others. Here, the processes of handling, transport and storage result in the emission of particles due to external stresses. This discharge of material is also referred to as dusting.
The aim of the project is to demonstrate the effectiveness of the dust reduction measure "use of spray nozzles" in combination with the effect of electrostatic charging. The special feature here is that the investigations are oriented to the type of stress and the material and thus take into account the character of the dust discharge. Different test set-ups are used to realistically illustrate the handling operations during which dust is released. The effectiveness of the reduction measure is investigated under different operating parameters. The subsequent electrostatic charging of the spray mist allows the use of water and compressed air to be reduced and a standard for reduction adapted to the dust generation to be determined. An evaluation method for spray nozzle systems is being developed, which provides an assessment from the point of view of the economy of the resources used and the material-related efficiency of the abatement. This is to be made available to SMEs and thus simplify the choice of suitable dust reduction measures...
Concept for jet-based direct mixed aggregation in the gas phase
J Witte*, E. Schmidt, University of Wuppertal, H. Kruggel-Emden, Technical University Berlin, Germany
The overall objective of the research is to contribute to the development of new particulate products based on heteroaggregates formed in the gas phase. To achieve this goal, gas-phase-based processes must be established that allow the controlled formation of the aforementioned aggregates in sufficient quantity and quality.
Since the processes for this are clearly still lacking, a beam-based process is being developed, realised and simulated. The beam-based process comprises three steps. In the first, the various primary particles are dispersed and dosed as part of a carrier gas stream. In a second step, the jets interact with the different primary particles, contact occurs, allowing the formation of heteroaggregates. In a third step, the formed products have to be removed from the aggregation zone in a controlled manner.
Currently, the process parameters of the described process as well as the three sub-processes are unknown with regard to optimising the throughput and the quality of the formed heteroaggregates. The overall process including the three sub-processes must therefore be investigated in greater depth, which requires a process analysis that can be carried out offline on the basis of the aggregates formed. Spatially resolved insights into the process are obtained by laser light diffraction and characterisation of the flow field. In addition, the structure of the formed heteroaggregates should be assessed by offline imaging techniques (SEM, EDX) to link the structure to the properties of individual aggregates.
Since the time and length scales are small and therefore challenging, the gas phase-based process will also be mapped within a DEM/CFD framework. After a suitable model calibration and model validation, which is achieved by detailed benchmarking with the experimental investigations, process details that are not experimentally accessible will be addressed...
Investigation into paper dust formation during knife edge cutting
J. Lunewski*, E. Schmidt, University of Wuppertal, Germany
Especially in the field of paper and print post-processing on an industrial scale, continuous knife edge cutting and shearing operations generate paper dust. Despite preventive measures like dedusting units, the high paper web velocity induces the particulate dust release. As a result, the dust particles settle and accumulate on machine components and in the surrounding area. Resuspended particles around a potential ignition source represent a fire hazard. Another exemplary problem relates to particulate paper constituents adhering to greased ball bearings of conveyor systems. In the worst case, the heat transfer restriction increases the surface temperature and triggers an ignition of the paper web. Frequent servicing and maintenance prevent such fire incidents. However, the shutdown time during manual paper dust removal on industrial scale applications remains cost-intensive.
The main objective of this research project is to identify significant parameters affecting the release of paper dust particles on a micro scale. In this context, a cutting plotter executes the reproducible movement of cutting tool operations...
Performance of a sampling cyclone at different flow regimes
D. Misiulia,*, S. Antonyuk.a, Technische Universität Kaiserslautern, Germany; G. Lidén, Stockholm University, Sweden
Personal cyclone samplers have been widely used to measure the respirable mass of particles in occupational and ambient environments. In respirable dust sampling, it is essential that the cyclone cut-off characteristics be known and constant, and that each cyclone be operated at a flow rate which produces the desired cut-off.
The aim of this work is to investigate the ﬂow pattern and performance of a sampling cyclone at different flow rates and reveal the dependence of main cyclone performance characteristics on flow rate (Reynolds number) using Large Eddy Simulations (LES)...
Retaining hazardous gases towards enhanced protective equipment
A. Polyzoidis *, C.-G. Piscopo, M. Weinert, Fraunhofer Institute for Chemical Technology ICT, Germany
Due to their exceptionally high specific surface area and porosity, coupled with a great tunability of their chemical properties, Metal-Organic frameworks (MOFs) are promising candidates for irreversible trapping of toxic gases. Combining the conventional state-of-the-art sorbents, like active carbons, with MOFs, can lead to compounds that achieve a higher adsorption potential especially for polar gases allowing the manufacture of a new generation of clothing and respiratory cartridges that provide protection against a wider range of toxic substances at the same time.
The first step to successfully implement MOFs in protective clothing and respiratory cartridges includes the identification and selection of suitable candidates. Micro-breakthrough experiments of various gases (e.g. NH3, H2S etc.) conducted on several MOFs structures revealed that...
Application of box-behnken design methodology for the optimization of nanoparticle collection by a spray scrubber operated under waste incineration conditions
E. Adah*, A. Joubert, Laurence Le Coq, IMT Atlantique ; M. Henry, S. Durécu, Séché Environnement, France
Nanomaterials (NMs) are increasing used in industries such as healthcare, cosmetics and agriculture. As a result, the likelihood that NMs will end up in the natural environment and adversely affect both the environment and indeed humans have increased in recent times. In the absence of regulations on the end-of-life management of NMs, they are treated via recycling, composting, incineration and/or landfilling. To date, only a handful of studies have been conducted on the fate of NMs in waste incineration plants particularly on the removal efficiency of nanoparticles emitted by the flue gas cleaning technologies (FGCT) present in these plants. As part of the FGCT used in waste incineration plants, scrubbers aid to remove acid gases, but they are also capable of collecting particles. The collection of particles by scrubbers is governed by several particle collection mechanisms with the primary ones been impaction, diffusion and interception. Conventionally, scrubbers are believed to be ineffective for the collection of particles less than 5 µm. However, research by Kim et al. (2001) established that under favorable operating conditions, scrubbers could be effective in collecting smaller particles. A review of the literature revealed that no study has been carried out on the capture of nanoparticles (NPs) by spray scrubber under waste incineration plant conditions.
To bridge this knowledge gap, the present study employs a design of experiment methodology (Box-Behnken Design) to evaluate the effects of the operating parameters of a spray scrubber on its NPs collection efficiency. The collection of NPs is evaluated from...
Coronavirus, filtration efficiency and the advancement of industry testing
N. Sasher*, AAF Flanders, USA
Air quality has profound health implications in all indoor environments where the world’s population normally spends most of their time. The quality of indoor air is therefore a prominent public health concern that requires a clear understanding of the transmission processes for the development and implementation of targeted infection prevention and control measures. World-wide outbreaks of severe acute respiratory syndrome (SARS) and other viral agents have caused a substantial health impact to the population and have increased public concerns for the spread of viral disease. The global pandemic caused by the novel coronavirus SARS-CoV-2, which causes the disease known as COVID-19, has changed the world in ways no one could have imagined. There is much more to learn about this ever-changing global threat, however, there are some aspects of the virus that are known such as its main route of transmission being that of an airborne nature and therefore, there is a strong desire to mitigate risk to the general population through the use of engineering controls such as filtration. Utilizing a test method developed and adopted at AAF International in collaboration with the University of Minnesota in 2018, a test for virus removal efficiency of air filters based on ASHRAE 52.2 methodology and transport particle capture was implemented as a first in the air filtration industry. At the beginning of the pandemic, AAF’s Biological Research Department launched a study utilizing a safe surrogate for the SARS-CoV-2 virus in order to evaluate the virus removal efficiency of several filters ranging in efficiency ratings of MERV 14-16. Air samples containing surrogate virus were collected upstream and downstream from the filters using aerosol test equipment such as Anderson Cascade Impactors and optical particle counters to be able to separate particles by size (approximately 0.3 to 10 microns). Then the samples were tested by quantitative reverse transcription polymerase chain reaction (RT-PCR) and a fluorometer to estimate mass. For each particle size, the particle size removal efficiency was calculated. The results showed that under the conditions of the study, filter efficiency for SARS-CoV-2 surrogate virus was comparable to filter efficiency using KCl particles (ASHRAE 52.2 standards). In addition, the efficiency of particle removal...
Masks characterization for nanoaerosol maximum
T.C. Passos Pereira*, B. de Araújo Lima, M.L. Aguiar, Federal University of São Carlos, Brazil
The COVID-19 has spread all over the world due to its high transmission rate. Because of this, demand for PPE’s has increased to protect frontline health professionals and the population. Therefore, studies are being carried out to improve PPE's, promoting better protection for people. The objective of our study was to propose methodologies of characterizations more appropriate for filter materials, such as surgical masks. We perform filtration efficiency and differential pressure (breathability) tests according to The Brazilian Standard ABNT NBR 15052 (2004). The standard proposes that the particle filtration efficiency test be performed with latex, particles of 100 nm and flow rate of 4.67x10-4 m³/s. After performing these tests, we changed the particle to NaCl and performed the test for flow rate of 4.67x10-4, 1.17x10-4 and 6.67x10-5 m³/s. These last flows were chosen after the study of the American Standard F2299 (2017) which proposes to use face speeds between 0.005 to 0.25 m/s. We tested 6 different masks, including one for non-professional use. The results exposed that...
Hybrid carbon nanotube active filters for virus and pathogen removal
L. Issman, M. Pick, Q-Flo Ltd., B. M. Graves, J. Terrones, M. Hosmillo, R. Qiao, M. W. J. Glerum, I. Goodfellow, J. A. Elliott, A.M. Boies*, University of Cambridge, UK; S. Yeshurun, Tortech Nano Fibers Ltd., Israel
To reduce ambient concentrations of viral particles, filtration media must allow for high fluxes of gases at low static pressure loss with high rates of particle removal and viral trapping or deactivation. Nanofiber-based filtration can achieve high aerosol filtration efficiency while exhibiting low-pressure drops. Here we report the first mass-producible air filter to possess HEPA-like pressure drop and efficiency, which is simultaneously self-sanitizing. The active filtration system is based on an electrically conductive, hybrid CNT-polyester mat that can rapidly be sanitized via resistive heating. Our material meets all relevant metrics required for HVAC filtration (i.e. filtration efficiency, pressure drop, heating rate, disinfection capabilities and price). The multifunctional aspect of the hybrid filter allows its implementation in an innovative HVAC filtration system that can act as an advanced alternative to current solutions, especially being able to tackle the well-known surface persistence of the SARS-Cov-2. The mat is produced via the direct CNT spinning method by the floating catalyst CVD (FCCVD) process. Tests showed...
Batch filter centrifuges - Software supported and reliable scale-up with minimal experimental effort
I. Nicolaou, NIKIFOS Ltd, Cyprus
The reliable scale-up and optimization of soft is a big filtration challenge due to the complex phenomenology. That is why pilot tests are necessary. By not considering the up-to date theory for the steps cake formation, cake washing and cake deliquoring, such pilot tests are carried out unsystematically. Such approach is usually too time consuming and uneconomical. In this paper it will be explained how a cobination of laboratory and pilot tests can minimize the experimental effort for a reliable centrifuge scale-up. A novel, theory and computer based approach for the analysis of laboratory and pilot test data will be presented. This theory considers in a big extent the real phenomenology in the centrifuges like intermittent suspension and wash liquid feeding, cake compressibility and depending on the cake compression different cake heights and cake resistances for each step.
It will be explained, which suspension and cake characterizing parameters (so called efficiency parameters) are needed for reliable performance predictions for all steps: cake formation, cake washing and cake deliquoring. Taking a real case as example, it will be demonstrated by using the software CENTRISTAR how the test measurements can be analyzed and judged and how the efficiency parameters can be determined...
Modeling cake formation within a basket-type vertical centrifugal filter using the discrete element method and high-performance computing
D. Serper*, M. Lafont, P. Oinas, Aalto University, Finland; K. Hanley, University of Edinburgh, UK
Centrifugal filtration is widely applied in the bio/pharma and chemical industries, as well as in laboratory-scale scientific research. This unit operation comes with its complexities in terms of modeling and simulation, which along with the scarcity of computational resources, has resulted in simplified mathematical models that are not adequate for industrial application. Recently with the increased availability of computational resources, Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) coupling has become a candidate for modeling centrifugal filters with differing geometries and complexities. Here, the aim is to model cake formation in a vertical, basket-type centrifugal filter focusing on the solid phase as a first step...
Cyclonplus - A novel software for the analysis of hydocyclone test data and the design and performance calculation of hydrocyclones
I. Nicolaou*, NIKIFOS Ltd, Cyprus
In this paper a novel software for the theory based analysis of hydrocyclone test data and the design and performance calculation of hydrocyclones (parallel connection considered) with reliable and physically based mathematical models is presented. The reliability is due to the used adaptation parameters, which depend on the given suspension and the given cyclone geometry and can be determined by analysis of test data. Characteristic to this tool is the highest flexibility regarding the input parameters. For example, we can design a hydrocyclone (diameter D, number of cyclones in parallel connection n, underflow (apex) diameter Du) for definite (required) solids mass fraction in the underflow (Cmu) and simultaneously demand a definite clarification or classification result for the overflow, as for example 90% of the solids in the overflow should have a particle size smaller than a definite entered size (x90o) and additionally demanding a definite flow rate Q and definite pressure drop Dp. The program calculates and displays for each simulation the particle size distributions, the flow rates and the solids content of overflow and underflow as well as the total efficiencies ET, ET’ and the grade efficiency curves G(x) and G’(x) of the hydrocyclone.
What makes the program more user-friendly is that all calculations including tables and graphs are taking place/displayed in one window with automatically updating of the diagram and table with any change of the input parameters. Any material or setting parameter can be systematically varied and its influence on any result parameter can be studied. For example we can study how the diameter of the hydrocyclone influences the cut size, the total efficiency, the particle size distribution and solids content of the overflow and underflow...
Bernoulli offers a solid basis for crystallization
H. Meldau*, Sulzer Escher Wyss, Germany
The state of knowledge about crystallization is associated with the names Mersmann, Mullin and Randolph and Larson, who showed 40 years ago that the average crystal size in stirred crystallizers is < 1 mm
Crystallization and crystal solvation are opposing physical processes in the tiny cosmos of nanoparticles. They occur in the boundary layer on the crystal surface. The reaction enthalpy that is implemented in these processes is 3890 J / mol for NaCl.
1 Mol = 6.022 1023 Particle
1 J = 0,624x1019 eV
Related to a NaCl molecule these are:
RENaCL = 40,31 x 10-3 eV
Where's the energy that is permanently fed into the process? It is converted into kinetic energy, which serves various consumers or degrees of freedom in the turbulence area and thereby releases many molecules.
This locally increasing supersaturation with hydrated ions is neither visible nor measurable. However, the effect is convincing. A large number of very small crystal nuclei form spontaneously while releasing energy. Waste heat resulting from this process increases the temperature of the suspension insignificant. But the formation of these small crystal nuclei are extremely undesirable. The reduction of energy supplied helps here.
It is not necessary to keep crystals in suspension. A slowly sinking crystal should not be stopped and its growth should not be disturbed by unnecessary energy input. If the crystal is down, it can be transported with little energy back to the place where supersaturation is generated.
The Bernoulli principle makes this possible with many economic consequences.
Production and separation of temperature-sensitive crystals on an integrated, quasi-continuous laboratory plant
T. Dobler*, B. Radel, M. Gleiß, H. Nirschl, Karlsruhe Institute of Technology (KIT), Germany
For the production or purification of temperature-sensitive products, crystallization followed by solid-liquid separation is a common process. Typically, the individual process steps are carried out batch-wise and on different devices, which in turn entails a number of disadvantages. These include deficits in the area of process efficiency, the risk of product contamination during transfer between the individual apparatuses as well as the need for transport equipment (e.g. pumps or pipelines) and the implementation of existing safety standards.
To minimize the mentioned problems, the development of integrated, (quasi-) continuous plant concepts becomes more and more significant. One example of such a concept is the so-called Enhanced Belt Crystallizer, which is an advanced version of the Belt Crystallizer and combines the process steps crystallization, ripening and solid-liquid separation on a single device.
In the poster contribution, the basic concept and its technical implementation will be presented. Subsequently, the plant functionality is demonstrated using lysozyme as a material system. Thus, the conventional production and separation process is successively transferred to the Enhanced Belt Crystallizer...
Magnetic seeded filtration as a holistic solid-liquid separation concept
F. Rhein*, H. Nirschl, Karlsruhe Institute of Technology (KIT), Germany
The demands on separation technology have steadily increased over recent years. Highly specific, selective separation techniques that are also suitable for fine particles in dilute suspensions, are needed more and more. In this work, magnetic seeded filtration (MSF) is presented as a separation concept that is capable of handling these challenges. Here, magnetic seed particles are added to a suspension and after agglomeration with the target particles, the agglomerates are removed by magnetic separation. However, the necessity of adding magnetic material is economically and ecologically questionable and is the main point of criticism against the process.
In the scope of this work, it was shown that high separation efficiencies of up to 95% on a broad parameter scale are achievable with MSF, even in dilute suspensions with particle concentrations of under 10-2vol%. Moreover, the electrostatic interactio..n
Adsorption of microplastic particles on the surface of freshwater plants
A.-C. Swertz*, E. Schmidt, University of Wuppertal, Germany
Plastic litter is a severe problem of modern society gaining more attention in recent times. The term “microplastics” is often used in this context referring to small plastic particles or fibres with a diameter < 5 mm. These particles are not only widespread in marine environments but can also be detected in inland water bodies and soils. Although modern sewage treatment plants can retain most of the incoming microplastic, a small fraction finds its way into rivers with the final effluent.
At the Institute of Particle Technology of the University of Wuppertal, the adsorption behaviour of microplastics on the surface of freshwater plants was studied.
As a first step, a benchtop experiment was realised to observe the general interaction of plastic microparticles (e. g. PE and PVC) with common freshwater plants as rigid hornwort (Ceratophyllum demersum) or eelgrass (Valisneria sp.). The adsorption of microplastics on the plant’s surface has been analysed using light microscopy with visible and UV-light as shown in figure 1.
As the lab experiment could successfully show that microplastics have a strong adsorption behaviour on the surface of aquatic plants, the contamination of plants from inland water bodies were analysed. For this purpose plant material was collected from different spots in Ruhr river. Parts of these plants were examined using light microscopy with visible and UV light, as shown in figure 1.
The method of the lab experiments and the first results regarding the distribution of aquatic plants with adsorbed microplastics in the environment will be presented in this paper...
Hydrocyclone for reduction of abrasive wear in sand trap piping of wastewater treatment plants
T. Senfter*, B. Stern, M. Berger., M. Pillei, M. Kraxner, MCI Management Center Innsbruck; H. Erber, Innsbruck Municipal Administration, Austria
Sand traps are typically installed in wastewater treatment plants for the removal of abrasive particles from the inlet flow. The particle rich water at the lower stage of the sand trap is pumped to a second sedimenter, which is connected to a sand washer.
Particles, which cannot be separated by the second sedimeter, are pumped back to the inlet of the wastewater treatment plant. This leads to a recirculation of the non-separable particles and results in abrasive wear in the first stages of the wastewater treatment plant.
For the removal of these particles a hydrocyclone was installed in the recirculation line of a wastewater treatment plant (capacity 400.000 population equivalents) in Austria. The system was investigated in terms of optimum operational parameters (high separation efficiency, low pressure drop) and separated particles properties (particle size distribution, composition). The hydrocyclone was operated in bypass-mode with an inlet flow rate of 3 m³/h and 1.93 kg/h of particles (average) were separated. The separated particles (median diameter 1.1 mm) consisted of 50.12% organic and 49.88 % anorganic material (average).
It was shown, that...
Imperfections in wash liquid application during displacement cake washing processes
H. Henn*, B. Hoffner, Mannheim University of Applied Sciences, Germany
Cake filtration is a common process, which is used in various industrial sectors (e.g. chemical, pharmaceutical, energy) for solid-liquid separation. Frequently the filter cake is washed in a subsequent process step by a displacement washing with a molecularly miscible liquid to remove impurities or valuable substances dissolved in the pore liquid. The aim here is to achieve a given residual impurity content with minimum use of wash liquid and equipment allocation in order to achieve the most economical process.
The physical principles of displacement washing of saturated filter cakes have been known for many years, the research findings are already being applied in practice. However, previous research work is based on highly simplifying assumptions, e.g. a homogeneous cake geometry and structure and no deformation of the cake surface due to wash water application.
In reality, deviations from these simplifying assumptions frequently occur, which can negatively and uncontrollably influence the course and result of a filter cake washing process. This leads to an increased demand of wash liquid and/ or an extension of the process time. The presented study is mainly concerned with imperfections caused by the wash liquid application and the interaction with the cake surface. The main focus lies on the reproducible experimental creation of imperfections as well as their description and quantification...
Impact of geometric cake imperfections on displacement cake washing processes
F. Sauer*, B. Hoffner, University of Applied Sciences Mannheim, Germany
A well-known and frequently used method for solid-liquid separation in the industrial environment is cake filtration using gas differential pressure fields. Due to dissolved impurities within the pore liquid of the filter cake, usually a displacement washing is performed as an additional process step. The reduction of these impurities within the filter cake is to be accomplished by requiring the least possible amount of wash liquid, time and filter area. In order to meet given specifications in terms of residual impurity content, the amount of wash liquid and/or wash time have to be adjusted, as well as potential predewatering and postdewatering steps.
The underlying transport mechanisms during displacement washing are widely understood and allow the design and operation of industrial processes based on laboratory experiments under certain assumptions. However, little attention is paid to the gap between these laboratory experiments and a real process, which can be caused by various imperfections (e.g. reslurrying of the filter cake during wash water application, inhomogeneous filter cake structure, uneven filter cake height, etc.). These imperfections can usually be neglected on small scale equipment but may dominate real processes on a larger scale, leading to an increase in washing effort and cost. This ongoing study is concerned with replicable geometric imperfections of the filter cake and their effect on the displacement washing process. Their impact is investigated in experimental studies, as well as theoretical studies applying the dispersion model. The aim is not only their qualitative, but also their quantitative evaluation on the course of the washing process...
Comparative study of dehydration performance with filterpress of waste sludges pre-treated with hydrothermal carbonization
D. Pirini*, D. Collini, B-PLAS Sbrl; F. Kaswalder, N.M. Finocchiaro, Aqseptence Group S.r.l. , Italy
Sludges from civil and industrial WWT plants and from agri-food industry are a growing problem throughout the EU, due to a production trend growth faster than the availability of disposal plants (landfills and incinerators), and due to the tightening of regulatory constraints and chemical-physical limits that make the spreading in agriculture as a soil improver possible. For this reason, the urgency to reduce the volumes of sludges to be disposed of, improving the performance of dehydration technologies, is increasingly pressing.
This work reports the comparative study of the dehydration performance of the sludge module of the innovative industrial process B-PLAS®, applied to sewage sludge from different sources: WWT primary sludge, WWT post anaerobic digester sludge, WWT mixed sludge, sludge from anaerobic digester of a biogas plant treating agri-food waste...
Description of the properties of filter media for surface filtration in automatic filters
T. Buchwald*, U.A. Peuker, Technical University Bergakademie Freiberg, Germany
Whenever large quantities of liquids need to be cleaned of small amounts (in the ppm–range) of suspended solids, automatic filters are used, which clean the filter medium after a certain threshold (time or pressure drop) is reached. Commonly, the medium is backwashed with filtrate and the resulting liquid containing the concentrated particles is discarded. In order to determine the efficiency of a filter medium in regards to separation size, solids capacity and tendency to blocking, all relevant process variables need to be constantly monitored.
This is achieved in a laboratory filtration apparatus, which semi-automatically backwashes a planar filter medium with an effective diameter of 100 mm. The process variables pressure drop, volumetric flow rate, the liquid’s turbidity at the inlet and outlet of the medium, and the cleaned filter resistance are monitored. In addition...
Development of a standardized measurement method for ESD (ElectroStatic Discharges) in hydraulic filters
F. Pedroli*, A. Ripamonti, C. Mazzucchi, M. Sanna, A. Negri, MP Filtri S.p.a., E. Villa, Università degli Studi di Milano, Italy
In hydraulic filters, electrostatic charges are generated by triboelectric effect occurring every time hydraulic fluids are traversing insulating filter medias. For this reason, generation of electrostatic charges is a phenomenon always present in hydraulic filtration systems when insulating materials such as paper and glass fiber are used. In most cases, when systems are not able to dissipate the electric charges, accumulation of this latter results in strong ESD (ElectroStatic Discharges), which are detrimental for both filter element integrity and environmental safety. In practice, when ESD occur internally within filter housing they consist in a local electrical-breakdown of hydraulic oil (namely sparks) followed by an extremely high local increase of temperature (in the order of thousands of Celsius degree) leading to irreversible damages of filter element components (filters media, sealing parts, end-cups) and hydraulic fluids. Moreover, an electrostatic potential is induced on filter housing and may reach values close to air electrical-breakdown (⁓50kV). If this occurs, electrical arcs develop in air and along pipelines bringing to high-risk industrial environment (explosion, electrical shocks, etc.) for humans and hydraulic system components (filter indicators, pumps, electrical apparatus).
As discussed in previous section, ESDs are the results of an unbalanced situation between electric charge generation and dissipation. This work aims at developing a robust and standardized method, which is able to evaluate and quantify these two electrostatic phenomena occurring within hydraulic filters...
Innovative arduino-based sensor kit for online monitoring of growth and well-being parameters in a smart shrimp farm
F. Boruta*, P. Rinn, O. Schmitz, M. Ebrahimi, University of Applied Sciences Mittelhessen; P. Czermak, Justus-Liebig University, Germany
In the context of the bioeconomy, the trend towards improving fish stocks worldwide is increasingly moving towards fish farms. The project described here aims to develop an overall system for marine animal husbandry. Starting with the design of an online controlled measurement system for monitoring water quality parameters for sensitive shrimp species and other edible fish in tank farms, improved and flexible sensors will be used for the desired application, while providing high coverage of relevant parameters. Furthermore, the developed measuring instruments are used to monitor the standards to be met for the cultivation of insects by using biogenic waste materials. To achieve this goal, water quality is of crucial importance and can be kept stable in this sensitive ecosystem by the adaptable online sensor technology. The cost of an entire measurement system is usually very high for existing techniques due to the large number of parameters to be covered in different ways, and the economic benefits for the development of sensors for parameters that are not often in demand is necessarily high, so this is the starting point for development. The first prototype shows a stable data recording of the measured values of a multitude of simultaneously recorded parameters at low costs, with the planning to integrate further parameters into the system in the future for a greater flexibility at application sites...
16:00h - Poster Viewing
Day: 09 March 2022
Time: 16:45 - 18:00 h
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New plasma nanocoatings to boost performance of filtration media and their relevance to the fight against COVID-19
F. Legein*, Europlasma NV, Belgium
Plasma is a unique technology to deposit ultra-thin coatings on all exposed surfaces of a material or product. It is increasingly used in manufacturing of filtration media and elements to achieve functionalities such as hydrophilic, hydrophobic or oleophobic. Improvements in process and machine design allow to deposit the coatings in a very cost effective way, with a process that is completely dry and clean. The technology is giving an increasing number of producers of technical nonwovens, membranes, mesh or nanofibers a clear competitive edge. The presentation will introduce a new generation of plasma nanocoatings specifically designed to boost performance of electret filter media and discuss their relevance to the fight against COVID-19.
The presentation will start with a short introduction of plasma technology.
Then it will review industrial concepts for both batch and roll-to-roll treatment. It will also compare industrial equipment for atmospheric and low pressure plasma deposition. An overview will be given of typical coating chemistries used for such coatings.
Subsequently advances will be discussed using real industrial case studies.
One case study will discuss the use of hydrophilic nanocoatings for culture growth media. Another case study will review the use of similar nanocoatings for blood filter media.
One of the key areas of interest is the nanocoating of electrets used in HEPA filters. A new generation of plasma nanocoatings (Nanofics E) specifically designed for electrets will be discussed. Advances in process chemistry allow to deposit coatings which boost and maintain filter efficiency over time, while not affecting the pressure drop.
Also advances in durable water repellent coating of membranes for use in sporting and outdoor jackets will be discussed.
The presentation will conclude with an overview of the societal and environmental benefits of plasma technology, with a special focus on the importance of nanocoated electrets in the fight against COVID-19.
PlasmaMAX™ a versatile tool for high-functional coatings on filtration media and technical textiles
J. Jolibois*, H. Weiss, AGC Interpane Demonstration and Research Center, Germany; G. Arnoult, J. Schotsaert, H. Wiame, AGC Plasma Technology Solutions, Belgium; C. Gottlieb, AGC Business Development, USA
Conventional repellent coatings for filtration media are mainly based on long perfluoroalkyl chemicals (PFAS), deposited through wet coating or padding process. However, PFAS are subjected to restriction by REACH and in case of PFOS (i.e. C8) banned for use. In addition, wet processes require huge inputs of energy, water, and chemicals. The growing environmental and energy-saving concerns are incentives for the well-established surface finishing industry to gradually substitute many traditional wet chemical-based textile processing by dry-finishing processes such as plasma. Until now, plasma technologies have not yet proven to be really suitable for textile applications. Problems related to current plasma sources are the difficulty to scale up them for substrate widths beyond hundred centimeters resulting in poor uniformity and low durability of the deposited functionalities, and high OPEX.
PlasmaMAXTM developed by AGC Plasma is a cutting-edge technology designed to address different problems related to wet processes and overcome weaknesses of commercially available plasma systems. Technology core of PlasmaMAXTM is hollow cathode (HC) plasma source. This source can achieve high deposition rate with high uniformity (± 1% across 1-m web width) and allows functional coating without damaging the web. Functional coatings are deposited via plasma-enhanced chemical vapour deposition (PECVD) at low pressure. HC-PECVD is achieved by introducing reactive precursor gas in the vicinity of plasma area (see Figure 1). Chemical reactions are initiated by plasma-precursor interaction inducing the growth of functional thin-film (e.g. water repellent finish) on web surface.
In the present work, durable water repellent (DWR) and oil repellent coatings made by HC-PECVD on different types of substrate (e.g. PE woven) are shown. Then, we will discuss on how plasma parameters (i.e. pressure, power, precursor, etc.) modify the coating properties such as wettability, adhesion and so on. Finally, we will present two examples of HC-PECVD coatings, a DWR halogen-free finish and then oil repellent surface...
Lotus range™ filter media
T. Soyer*, Clear Edge Germany GmbH, Germany; D. Fogg, Clear Edge UK, UK
One major contributing factor that limits the service life of conventional filter media is blinding. This is caused by the constant ingress and accumulation of particulate matter inside the structure of the filter media. If unaddressed, this blinding results in a reduction in the cycle count or increased cycle times, reduced production rates and a decrease in throughput, an increase in the number of wash cycles, poor cake release, increased filter maintenance, premature wearing and holing leading to bypass and early failure as well as unscheduled changeovers leading to reduced machine availability and capacity.
Historically, the filtration properties of the fabric have been improved with surface chemical applications to address the above-mentioned limitations. The surface treatment eventually washes off during the process and the achieved benefits diminish with time and do not last the full lifetime of the media. To address this issue, Lotus Range™ filter fabrics have been invented with new release enhancing properties engineered directly into the yarn itself. This means that the achieved benefits can be seen throughout the service life of the filter media.
Multiple field trials were carried out in the mining and minerals as well as the chemical industry to validate this newly engineered technology. As a result of the anti-scale and anti-blinding properties, service life of the media was dramatically increased and fewer change overs meant greater machine availability and production output. The efficient cake discharge lead to a direct reduction in cycle time, this benefit can additionally reduce manpower and ultimately create a safer working environment. Efficient washing minimised solids residue and blinding which effectively results in lowered costs by washing with reduced frequency and less water consumption.
Overall the performance...
Filter testing according to ISO 29461 - Air intake filter systems for rotary machinery
M. Neukirch, C. Kappelt, A. Rudolph, C. Peters, S. Große*, Topas GmbH, Germany
For the application of rotary machinery the air filter systems are an essential component of the complete turbine/compressor system. The machines have become more complex over the last few years and therefore the protection of the machines is becoming more and more important. Particulate contamination with salt or other corrosive particles can significantly impair a turbine power system through erosion, fouling or hot corrosion. Another challenge is the different climatic conditions from desert, offshore, rain forest to arctic conditions.
Due to the different requirements for the filters, the ISO 29461 standard is divided into 7 parts. It should be noted, that part 1 is the only part which is already approved by the ISO committee, the parts 2 to 7 are still under development.
Topas has developed a test system that covers the parts 1, 5 and 7 of the ISO 29461 series of standards respectively of the drafts of the ISO 29461 standard. The presentation will show the latest state of the test procedure as well as the test system and focuses on the description of the fully automated filter test system with flame photometer and optical particle counters. Furthermore, important key components for filter performance testing like humidifier, water spray system and aerosol generators (DEHS, NaCl and ISO A2 fine dust) will be presented. As well as the evaluation of the obtained measurement data such as differential pressure, particle separation efficiency, water separation efficiency, dust loading, salt and water deluge challenge. The creation of a summary report, which includes all determined and recorded parameters for a direct interpretation of the test results, is also a part of the presentation...
PALAS - EN149 Penetration test – Uncertainties and physical background of the measurement technology
M. Schmidt*, PALAS GmbH, Germany
Face masks are currently and in future one of our major weapons to protect people from infections by airborne particles as viruses or bacteria.
As the perfect function of the mask is the basis for the safety of the user, these masks need to be tested concerning their performance in particle removal.
Standards as EN 149 in Europe, GB 2626 in China and 42 CFR 84 in United States must ensure a clear comparability of test results for the protection degree of the mask. Below is an extract of the main test parameters for the evaluation of face mask efficiency:
Comparable penetration test results in respiratory filter testing – From the QC-lab to the production line
J. Spielvogel*, S. Percot, TSI GmbH, Germany; T. Johnson, J. Koczak, TSI Incorporated, USA
Filtration products need to be regularly tested in order to assess the correct protection level against harmful airborne matter. It is also important, that equipment that is used for testing the filtration products gives consistent results. Usually test equipment can be verified by tracing the results to a standard. For respiratory filter testing commonly used standards are EN 143/149, 42CFR part 84, and GB2626. These standards define key parameters for testing such as flow rate, aerosol concentration, count median diameter, geometric standard deviation, and ambient conditions. Some standards also specify the test equipment. Still, measurements that are compliant to the standards requirements don’t necessarily result in consistent penetration test results. While count median diameter and the geometric standard deviation are accurate means to define a sub-micrometer particle size distribution, the aerosol undergoes changes in the aerosol path of the filter tester that can change the size distribution.
When TSI developed a new model filter tester, the model 8130A, which replaced the model 8130, TSI executed a detailed test matrix in order to obtain continuity of measurement results between models. It consisted of:
In conclusion, these tests showed an excellent agreement between the models 8130A and 8130 for every media/aerosol combination and at different flow rates with measured penetrations typically within ±10% of the global mean.
To apply these results to in-line production filter testing requires...
FILOS – Protocol & report for the filtration of suspensions a novel software tool for planning, analysing, judging, saving and reporting of measured and calculated test data
I. Nicolaou*, NIKIFOS Ltd, Cyprus
In this paper a novel and powerful module of the Filtration Software FILOS for entering and saving all known and measured data for every experiment of a given Filtration test series will be presented. Each experiment belongs to a definite test series and every series belongs to a definite project. Projects and Series as well as experiments of each series, test goal and tested steps for each experiment are listed in the first column (see figure below). The second column displays the geometrical parameters of the test apparatus and basic material data for the tested suspension. The data for each tested step (Cake Formation and the optional Steps: Cake Washing, Cake Squeezing and Cake Deliquoring) are displayed in a separate column. The Protocol is also a Calculator because it calculates and displays from the entered measured data the values of many important parameters, which enable the judgment of each experiment. All data of one test series can be transferred to the FILOS-Analysis modules for Detailed judgment and determination of the necessary efficiency parameters for the filter performance simulation. Highest flexibility regarding input and calculated parameters enables the use of Protocol even as a Simulator, which can be used even for the planning of the experiments. The Series Overview Table displays for comparison reasons all important input and calculated parameters for all experiments of the current test series...
The advantages of nonlinear regression of cake filtration experiments
Cake filtration data, in the form of filtrate volume Vf = f(t), i.e. as a function of time, is commonly fitted in the linearized t/Vf–Vf–plot to gain knowledge of the specific cake resistance and the filter medium resistance. There are some apparent shortcomings to this method, most commonly errors in the determination of the Vf (t)–data, which will lead to the resulting plot deviating from the ideal, linear slope.
These problems can be overcome by fitting the original Vf (t)–equation nonlinearly. This can be achieved by any modern statistical software. The method offers many advantages, most prominently identifying initial parts of an experiment where cake filtration may not be the dominant process. Data with non–constant pressure can be fit by use of the pressure–time integral. Moreover, additional models can be incorporated into the nonlinear equation, which can give information on, for example, cake compressibility. Additional knowledge may be gained in the beginning of the filtration process by fitting models for blocking filtration.
The paper presents a method for nonlinear parameter estimation of cake filtration data. The method was tried on a dataset of 225 cake filtration experiments and was found to be superior to the linearized regression method by reducing errors due to time offset and transformation of the dependent variable. New findings...
Digital design of continuous filtration processes via mechanistic modelling
B.A. Mehta*, Siemens Process Systems Engineering Ltd; N. A. Mitchell, C. Brown, S. Ottoboni, University of Strathclyde, UK
The separation of solid particles from liquids via filtration is a key unit operation in the pharmaceutical sector. This processing step normally occurs after crystallization of an Active Pharmaceutical Ingredient (API) and could include a number of wash cycles in order to deliqour the cake and remove any residual solvents and other impurities below specified limits.
In this work we detail a digital design approach via mechanistic model-based workflow for the modelling of a filtration unit, with a view to developing an optimized continuous filtration model...
Using ceramic fibres for enhancing filtration efficiency in al-melts based on a room-temperature model system
D. Hoppach*, U.A. Peuker, Technical University Bergakademie Freiberg, Germany
Al-melts contain non-metallic inclusions, which have a negative influence on mechanical properties. Therefore, ceramic foam filters are widely applied for the cleaning of the Al-melt by removing these solid impurities.
With increasing inclusion size it is well known that particle separation within a ceramic foam filter (CFF) is increasing. In contrast, especially particles in the single-digit µm range are difficult to separate at the filter struts due to weaker transport mechanism. Hence, larger amounts of impurities may remain in the ingot.
Moreover, a clustering of these inclusions, when not separated in the CFF, turns out to be detrimental in terms of material properties.
The application of CFF with elevated number of pores per inch (ppi), in this case 30, is a common solution for removing impurities in the given size range but is strongly dependent on the exerted casting process. But the usage of 30 ppi filters in the case of sand casting is already critical due to freezing of the melt in the filter and leads to abortion of the casting process.
A promising technique is the additional appropriation of ceramic fibres with diameters much smaller than the filter strut thickness. Already minor amounts of fibres increase the surface for potential particle separation and hence increase filtration efficiency. Furthermore, SEM analysis indicates...
Innovative two stage water filter
J. Roßbauer*, Grünbeck Wasseraufbereitung GmbH; M. Wilkens*, Hengst SE, Germany
“Water is life!” this simple sentence shows how important clean drinking water becomes, even in industrial countries. Due to this, the company Grünbeck, as a leader in water treatment solution and the company Hengst, known for leading filtration solutions in industrial and automotive applications, joined to start a cooperation to develop an innovative filter solution for hygienic water treatment applications.
The main target of the development is to find a mobile filtration solution for leisure vehicles, which can adapt to nearly all drinking water tanks to provide hygienic and pure water.
To ensure a filtration system which is reliable for nearly all drinking water standards a two-stage filter system with a minimum amount of auxiliary materials – for example without any kind of glue within the filter element – has been developed.
The filter element consists of two innovative filter stages with active carbon as, for example, an agent for the removal of chlorine and an additional material for the removing of pathogens and colloids.
Due to the use of the Hengst Energetic concept and ultra-sonic welding processes it is possible to produce a filter element that only consist of the filter materials and plastic components (end cap and inner tube), without any kind of glue or further materials.
The filter element is evaluated by several parameters, especially by retention of chlorine, turbidity and germ reduction...
Separation of varnish from turbine oil by adsorption technology
E. Barega*, T. van der Linde, John Crane Indufil, Netherlands
Recent developments in industrial turbines to improve efficiency resulted in higher firing temperatures. As a result of these extreme operating conditions, oil oxidation products and varnish are formed. At present, one of the solutions offered to remove varnish is filtration. However, filtration increases the energy consumption in cooling and later heating the lubrication oil. Additionally, filtration cannot remove the soluble varnish and frequent replacement of filters is required. Compared to filtration, adsorption provides a higher capacity due to its high specific area. Besides this, adsorption can remove both soluble and insoluble varnish. Nevertheless, some currently used adsorbents release unwanted substances such as water. Moreover, the adsorbents need to be replaced after use.
This paper presents a technology to remove varnish from lubrication oil using a polymeric adsorbent material...
Studying fouling behavior of layer-by-layer modified nanofiltration capillary membranes in water treatment and its effect on separation performance
H. Abuelgasim*, I. ElSherbiny, N. Meshki-Zadeh, University Duisburg-Essen (UDE); R. Niestroj-Pahl,inge GmbH - DuPont C. Staaks, Center for Water and Environmental Research; S. Panglisch, DGMT German Society of Membrane Technology, Germany
Recently capillary nanofiltration (NF) membranes are gaining attention because of more emerging restrictions regarding micropollutants in surface water and quality of drinking water. NF membranes can produce permeates of higher quality compared to ultrafiltration (UF) and might be less susceptible to internal pore fouling, which is one of the most prevalent fouling problems with UF. Nevertheless, the fouling behavior of capillary NF membranes and its impact on the retention of dissolved organics as well as monovalent and divalent salts is relatively poorly understood.
In this study, the performance of novel capillary NF membranes (MWCO ∼ 400 Da), prepared by layer-by-layer modification of polyether sulfone-based hollow fiber modules, is investigated during mini-plant filtration experiments employing synthetic model feed water, imitating moderately loaded surface water...
A dynamic transport model to predict evolution of nanofiltration performances in partial recycling and diafiltration modes
S. Déon* , B. Lam, P. Fievet, Université de Bourgogne Franche-Comté, France
Although many knowledge models describing the rejection of ionic compounds by nanofiltration membranes are available in literature, they are all used in full recycling mode. In these previous works, both permeate and retentate streams are recycled in order to maintain constant concentrations in the feed solution. However, such “steady state” approaches are not relevant for real applications. Indeed, nanofiltration of real effluents is implemented either in partial recycling (retentate only) or diafiltration modes, for which the permeate stream is collected during filtration. In these conditions, concentrations progressively evolve over time and classical models fail to predict performances.
Here, an improvement of the classic “Donnan Steric Pore Model”, which includes both volume and concentration variations over time is proposed. The model is based on...
Impact of sugar beet molasses purification by ultra – and nanofiltration on the 5-hydroxymethylfurfural production
M. Sjölin, M. Sayed, J. Thuvander, R. Hatti-Kaul, O. Wallberg, F. Lipnizki*, Lund University, Sweden
Today, sugar beet molasses is an underutilized by-product from sugar mills, which is mainly used as animal feed. However, the sucrose in the beet molasses is also interest raw material in the concept of biorefineries. 5-Hydroxymethylfurfural (5-HMF) has been identified as interesting platform chemical for biorefineries to produce different building blocks and polymers. However, since the 5- HMF formation process is affected by purity and concentration of the sugar compounds used, a pre-treatment of the molasses is required.
In this study, two different membrane processes - ultrafiltration (UF) and nanofiltration (NF) - were investigated and evaluated for the purification of the sucrose fraction from beet molasses...
Day: 10 March 2022
Time: 09:00 - 10:15 h
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Influence of an inhomogeneous material distribution on the overall filtration efficiency of fibrous media
C. Mercier*, R. Kirsch, S. Osterroth, S. Rief, Fraunhofer Institute for Industrial Mathematics (ITWM), Germany
It is well known that the level of uniformity of nonwoven filter materials is related to their filtration efficiency and therefore, this feature is an important subject to quality control (QC). The COVID19 pandemic has once again revealed the importance of efficient manufacturing processes for high-quality nonwovens, such as they are required for face masks that provide sufficient protection. While specialized 3D computer simulations have shown to be very helpful for the design and optimization of nonwovens, their computational cost is (in general) too high to allow for a quick assessment of the properties of a filter material. In addition, the acquisition of images of the microstructure created during production is not practicable.
This work is devoted to a fast and effective simulation-based analysis of the influence of the non-uniformity of the material distribution in nonwovens on their filtration efficiency. Both mechanical efficiency and the enhanced capturing due to fiber charging are included in the simulation model. ..
Simulation of slip flow for nanofiber filters
L. Cheng*, S. Linden, A. Wiegmann, Math2Market GmbH, Germany
When the air in motion contacts with a solid surface, usually the air is thought to be approaching to a complete stop at the surface, and the velocity is zero relative to the solid surface. However, when the solid is so small that when the air passes the solid, only a fraction of the air molecules contact the surface. As the result, only those molecules have their velocities changed. The remaining air molecules remain their bulk flow motion. When we still consider the air as a continuum, the air velocity near the solid surface is not zero. That is the phenomenon called as slip flow.
The slip flow effect explains the low pressure drop for nanofiber filters because fewer air molecules exchange momentum with the fiber, there is less air drag on the fiber leading to less energy loss. Also because of the slip flow, the flow streamline is closer to the fiber surface and the single fiber efficiency of small particles is increased on nanofiber . Therefore, the slip flow is a very important factor for nanofiber filtration. It must be considered when simulating the nanofiber filtration.
The slip flow was studied historically either with empirical equations or for very simple 1D or 2D structures, which cannot provide detailed information for a complicated 3D fibrous material structure. Cheng et al.  presented the approach to implement slip flow for 3D voxelized structures. In this approach, the expression of the slip velocity, which assumes the slip velocity proportional to the shear stress at the surface, is reformulated for a locally quadratic velocity profile instead of the standard linear profile, and reimplemented in our flow solver. The direct simulation of the slip flow is then possible, and it can be validated with analytic solutions.
The simulation results are compared to the newly obtained measurement data for nanofiber filters. The influence of slip flow in nanofiber structures then is studied and the results of flow and filtration simulations are presented...
Simulating filter quality of nanofiber filter: Effects of slip-flow and implications for filter design
Y.T. Chen, T.C. Hsiao, C.W. Lin, S.H. Huang, C.C. Chen*, National Taiwan University; Y.M. Kuo, Chung Hwa University of Medical Technology, Taiwan
This work presents simulated results of filter quality factors (FQ), also referred to as Figure of Merit (FOM), of nanofiber/microfiber mixed filters in order to produce the filter with the highest FQ. The computational scheme is based on the theory of single-fiber efficiency and the semi-empirical equation of pressure drop proposed by Davies (1953) and Bian et al. (2018). The equation cited here has considered the air molecule “slip-effect” on particle collection efficiencies and the pressure drop across the filter. We assumed here that filter with micro-size (1 μm) and that with nano-size (50 nm) contribute independently to the particle collections and air resistances. The results of pressure drop predictions, both with and without considering the effects of gas-slip on nanofiber were...
One step beyond: From the experimental investigation of discharging methods to numerical optimization potential of electret filter media
M. Kerner*, S. Antonyuk, Technische Universität Kaiserslautern; K. Schmidt, IT for Engineering (it4e) GmbH; S. Schumacher, C. Asbach, Institute of Energy and Environmental Technology e.V. (IUTA), Germany
Electret filter media are commonly used in aerosol filtration to remove particles from gases. They provide a high initial particle removal efficiency combined with a low pressure drop as the fibers of the electret filter media are electrostatically charged. In addition to the mechanical deposition mechanisms (diffusion, impaction and interception), charged particles are deposited by the Coulomb effect and any (charged or uncharged) particles by dielectrophoresis.
The high initial particle deposition is reduced with increasing filter life, as already deposited particles attenuate the electrostatic effects mentioned above. In the worst case, the electrostatic effects have vanished and the aged electret filter media become conventional mechanical filter media. With regard to the application, it is necessary that even the aged filter media achieve a minimum filtration efficiency. For this reason, testing standards for electret filter media take into account ageing by discharging the electret filter media or the entire filter with isopropanol.
In this work experimental investigations on the influence of discharging methods on ten different corona charged and triboelectrically charged electret filter media are performed by means of deposition experiments. The focus is on the discharging methods with isopropanol prescribed in DIN EN 779 (liquid isopropanol) and its replacement ISO 16890-4 (isopropanol vapor)...
Modelling of the mechanical aging behaviour of PLA-based nonwovens and monofilaments under filter application-relevant conditions
R. Taubner*, Saxon Textile Research Institute (STFI), Germany, C. Schippers*, L. Tsarkova, Deutsches Textilforschungszentrum Nord-West gGmbH (DTNW); J. S. Gutmann, University Duisburg-Essen (UDE), Germany
Nonwovens and felts from synthetic fibers (polyester, polypropylene) or from glass fibers are the mostly used filter media in air filtration. These materials offer high efficiency, long service life and a good price-performance ratio. However, the modern growing trend to replace petroleum-based fibers with bio-based and bio-degradable polymers dictates a new challenge for researchers, filter developers and manufatures.
Presented research focuses exploring PLA fibers as an alternative material for applications in air filtration. Particular emphasis was made on the characterisation of the mechanical properties of PLA monofilaments under aging conditions, which are relevant for the applications as filter media, with an aim to quantify the biodegradability of the PLA based materials. Furthermore, the air filtration characteristics of the PLA nonwovens depending on the textile media parameters were tested.
Multiple methodologies were used to characterise structural changes and mechanical properties PLA monofilaments before and after respective aging treatments. The results of the DSC analysis, tensile stress tests, 3D optical microscopy and scanning electron microscopy were...
Changing a filter – A change of principle
T. Stoffel*, DELBAG GmbH, Germany
The new filter classes based on ISO 16890 are already looking back upon more than four years since their approval, not only by national European bodies of standardization but industrial associations around the globe. Still, large portions of the facility management business segment have not yet fully embraced their existence. Even under the old standards, maintenance crews were more often than not confused about when to change filters in an air treatment system. To even add to their misperception, historically, various recommendations have in the past led to considerable confusion with installers of air filters about the legally required or economical optimum time to change the filter.
This essay should look back at the insecurity caused in the past related to filter change intervals. We will engage in the difference between the final pressure drop measured on the former EN779:2012 and the recommended air filter change intervals stated in the former EN13779. Both of these standards have long been replaced for some time: ISO 16890 for air filters and the ISO 16798 for air treatment systems. Unfortunately, none of the two regulations have given our global strive adapt the layout of air treatment systems and service thereof - to configure to real ambient conditions - any simplicity, or given more safekeeping for the consumer. Neither have the requirements for energy efficiency made the configuration and timely service of air filters any easier.
The European Energy Efficiency Directive was first passed by the European legislation 2009. It introduced an unprecedented SFP value to calculate the specific fan performance and the fans overall energy consumption in 2009 to asses each component of an air treatment system. Since then the filter community has relentlessly been heavily scrutinizing the SFP’s lack of evaluating the dynamic change of energy consumption caused by air filters.
Guided by the Eurovent energy ratings system for air filters, the EU is expected to pass a motion in 2021 to update the European Energy Efficiency Directive that shall plan to reflect new change interval for filters that will fulfill both initial claims. Not only will the service life of a filter reflect the ambient conditions, but it will moreover guide users to change intervals that will minimize energy costs induced by the air filters design and filter medium...
Grey-box modelling of decanter centrifuges by coupling a numerical model with neural networks
P. Menesklou, M. Gleiß, O. Zhai*, H. Nirschl, Karlsruhe Institute of Technology (KIT), Germany
Continuously operating decanter centrifuges are often used for solid-liquid separation in the chemical and mining industries. Simulation tools can assist in the configuration and optimisation of the separation apparatus, which means controlling the quality characteristics of the product. Increasing computation power has led to a renewed interest in grey-box modelling. The name is deduced from the fact that in the simplest case the model consists of two kinds of models. The white-box model is a representative example of known mathematical and physical relationships, such as analytical equations or numerical models, which often contain multiple assumptions. The black-box model, typically a regression model or neural network, requires a training data set and correlates a model, which is predicting output parameter as a function of input parameters. Combining both has the advantage that effects, which cannot be modelled with the assumptions of the white-box model, can be predicted by the black-box model if appropriate training data is selected for it.
In this presentation a grey-box model for the simulation of the mechanical dewatering of a finely dispersed product in decanter centrifuges will be discussed. Here, the white-box model is a numerical and dynamic process model, which considers the settling behaviour, the sediment consolidation and the sediment transport. The black-box model is a neuronal network trained with experimental data. Now, the simulation tool is able to check the accuracy of the model on the one hand, and on the other hand, effects that have not been modelled so far can be learned using training data with a neural network, thus extending the range of validity....
Method development for the resolved numerical simulation of mechanical solid-liquid separation in decanter centrifuges
H. Wettich*, M. Gleiß, H. Nirschl, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
The sustainable and efficient use of resources and plants while providing a high product quality is the challenge for the process industry in this century. Nearly 60 % of the processes in the chemical industry involve the production, processing and usage of particulate systems. One basic process operation is the separation of solids from liquids. For the separation of finest solid particles from liquids, continuously operating decanter centrifuges are commonly used on an industrial scale. The design of these apparatuses is based on simplified black box models for the stationary state. Though, the physical behavior of the separation process as well as sediment formation and its transport remain unconsidered in this approach. For the selection of a suitable apparatus as well as the optimum adjustment of the operating parameters, a large number of experiments on a pilot scale are necessary. However, changes in the material properties of the initial suspension can lead to a significantly different process behavior, so that different running parameters are required for an optimal operation of the apparatus.
Here, one challenge is that the process takes place on different time and length scales: The characterization of the disperse phase takes place at the smallest scale. Solids phase characteristics influence the separation-related material functions such as sedimentation, consolidation and sediment transport. In combination with the adjustable operating parameters, this defines residence time behaviour and flow conditions. Advancing digitalization can make an important contribution to a sustainable development under consideration of all scales. CFD simulation allows the resolved observation of the physical processes in the separation apparatus.
In this presentation, a simulation approach will be discussed which takes sedimentation, sediment formation and solids transport into account...
Simulation of multi-phase fluid flow in porous membrane boundary layer based on momentum sink added to navier-stokes equation
L.F. Esteves*, I.M.A. ElSherbiny, S. Panglisch, University Duisburg-Essen (UDE), Germany
Computational Fluid Dynamics (CFD) simulates the flow of liquids and gases, heat and mass transfer and any related behavior by solving the numerical equations that represents the physical models. In porous membrane applied to water treatment, which are characterized by the ability of physical separation between solid and liquid components, CFD analisys is typically carried out earlier in the design process before the first prototype for validation its performance. Although CFD has presented itself as an interesting alternative for modelling and simulating membrane filtration systems, developing a generic model able to encapsulate all aspects of membranes in complex geometries can be however quite challenging in terms of computational cost and calculation efforts. In this regard, a code package using SIMPLE algorithm with apropriate boundary conditions and parameters related to different types of membrane, from dense to microfiltration technique, has been used for simulations considering their specifications based on practical background. The main focus of this work is the simulation of a small rectangular area of cylindrical membrane geometry...
PES membrane fouling: Insights from fluid dynamic gauging and atomistic simulations
K. Arandia*, N.K. Karna, A. Larsson, H. Theliander, Chalmers University of Technology, Sweden
As a cost- and energy-efficient operation, cross-flow membrane filtration can be expected to be utilized in the future biorefinery. However, membrane fouling is inevitable in membrane operations, likewise for complex, heterogeneous mixtures of extracted wood components containing suspended particles and dissolved components. In recent years, various analytical techniques have been developed to characterize fouled membranes (e.g. streaming potential measurements, atomic force microscopy, and scanning electron microscopy). These methods have increased our understanding of fouling, but several fouling aspects are still poorly understood and as a consequence, fouling is still difficult to predict and model. In order to overcome this, a better mechanistic understanding of membrane fouling must be gained. One essential type of knowledge is in situ information of the conditions when fouling layers are formed. This study employs fluid dynamic gauging (FDG), an in situ, real-time monitoring technique, to estimate the thickness and the cohesive and adhesive strengths of fouling layers....
A graphical representation of membrane filtration with adsorption
B. Gu, L. Cummings, L. Kondic*, New Jersey Institute of Technology (NJIT), USA
We discuss mathematical modeling applied to the flow of particle suspensions through membranes, and in particular on the influence of membrane's internal structure on its flow properties and on adsorptive behavior. While in our previous work  we considered a simplified flow geometry, here we focus on a membrane filter based on a complex pore network illustrated in Figure 1 (pore network). We study the performance of such a membrane filter based on considering two criteria: 1) total volumetric throughput and 2) accumulated foulant concentration. We first formulate the governing equations of fluid flow on a general network. Then, we model adsorptive fouling by imposing an advection equation on each pore (edge) and imposing conservation of fluid and foulant volumetric flow rate at each pore junction (vertex), which yields a system of partial differential equations. We study the influence of three geometric network parameters on filter performance...
Membrane nano reactor with nano catalysts immobilized in membrane pores for enhanced catalysis
S. Fan*, Z. Xiao, Sichuan University, China
Membrane nano reactor can be obtained if nano catalysts can be immobilized in membrane pores with micro or nano scale. Multi scale synergistic enhanced catalysis can be achieved in this membrane nano reactor under the flow-through mode as the operation mode of conventional fix bed reactor. Enhanced contact between the reactants and nano catalysts without shaped can be achieved, and enhanced mass transfer can be achieved owing to the confined space effect of the membrane pores; Furthermore, uniform field distribution at the scale of catalytic bed layer can be achieved, owing to the uniform distribution of membrane pores. Therefore, the apparent reaction rate and products selectivity will be increased in this membrane nano reactor. Effective immobilization of the nano catalysts in membrane pores to realize the even distribution of nano catalysts along the thickness direction of the membrane is the prerequisite for this membrane nano reactor. In order to resolve this problem, flowing synthesis...
Coronavirus and bacteriophage removal in wastewaters using membrane distillation
M. Rezaei*, M. W. Hlawitschka, Johannes Kepler University Linz, Austria
The constancy of pathogenic viruses and bacteria in treated used water sewage conceives decontamination essential to realizing wastewater recycle. Membrane technologies such as reverse osmosis (RO) have bestowed encouraging outcomes for reuse utilization for virus and other pollutant discharges from treat wastewater sewages. Nevertheless, RO unfolds a concentrated stream that carries high amount of pathogens and pollutants that regularly demand processing and bulk cut before discarding. Membrane distillation (MD) is a separation method that proved to lessen RO retentate dimensions while enlarging the potable water supply. MD is likewise a twofold blockade strategy for virus elimination as it functions at an elevated temperature and penetrates solitary the vapor phase through the membrane pores. The impacts of temperature on feasible concentration of virus and membrane retention of viruses in MD are examined in this research using two nonenveloped phages commonly employed as surrogates for enteric virus and an enveloped pathogenic virus for SARS-CoV-2. The high retention of viruses and viral inactivation at high temperatures confirm that...
Degradation and removal of polyester microplastics via TIO₂/g-C₃N₄ photocatalytic membrane reactor
M. Sharifi Teshnizi, S. Ayoubian Markazi, H. Khoramshahi, M Karimi*, Amirkabir University of Technology, Iran
Microplastics (MPs) have become an emerging pollutant due to the expansive usage and improper management of plastic production. Up to 300 million tons of plastic are produced annually, of which around 13 million tons are discharged into aquatic environments. Microplastics are defined as plastic particles which are smaller than 5mm, and they have been classified into two types, primary MPs and secondary MPs. In addition, microplastics are diverse in terms of shape (fragments, fibers, bead, foam, etc.) and type of polymer (polypropylene, polyethylene, polyethylene terephthalate, etc.), among which polyethylene terephthalate microfibers due to significant population growth and thus increase the consumption of clothing made of Synthesized polymers have one of the highest abundances in the environment. Since wastewater treatment plants are one of the most important sources of microplastics entering the aquatic environment, it is essential to study microplastics' behavior in different treatment stages. Various methods such as filtration, coagulation, Electrocoagulation, and advanced oxidation processes (AOPs) have been identified to separate or remove microplastics from water sources. To the best of our knowledge, this is one of the first studies that has considered a type of photocatalytic membrane reactor as a novel hybrid process to investigate both partial degradation and then filtration of MPs and prevent them from discharging into the environment...
10:15h - Coffee Break
Day: 10 March 2022
Time: 10:45 - 12:00 h
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Simulation of particulate matter detachment and transport in wall flow filters using lattice Boltzmann methods
N. Hafen*, A. Dittler, M.J. Krause, Karlsruhe Institute of Technology (KIT), Germany
Wall-flow particulate filters are used for particulate matter (PM) removal from exhaust gas in a variety of aftertreatment systems of combustion engines. Here, they significantly reduce PM emissions. Inside these filters, the gas flow is forced through a porous wall between oppositely arranged inlet and outlet channels.
During this process, porous PM layers, which consist of both reactive and inert components, are formed inside the filter channels, resulting in an increase of the filter back pressure. This leads to the necessity of regenerating the filter by oxidizing the reactive components continuously or in reoccurring intervals and breaking up the continuous PM layer into individual layer fractions. When reactive-inert particulate matter structures re-arrange during the regeneration process, remaining inert material can be observed in different deposition patterns, impacting operational filter performance. The objective of this work is a deeper understanding of wall flow filter operational behaviour beyond sole engine applications.
Due to its massive parallelization capability, the Lattice Boltzmann Method has been shown...
Modeling and simulation of catalytic converters for exhaust gas after-treatment with GeoDict
A. Weber*, M. Azimian, Math2Market GmbH, Germany
Since many years, the software GeoDict is used to simulate filtration processes and modeling of filtration media. This includes simulation of the air flow inside the filter as well as tracking particles and simulation of their interaction on the filter surface.
In our newest version - GeoDict 2021 - we have adapted these functionalities for the simulation of Diesel Particulate Filters and Catalyst Monoliths. For example, new ways of modeling monolithic structures, detailed diffusive movement statistics, and 1st order reaction simulation are now available. These improvements aim to model and optimize air flow, soot filtering, and noxious gas reduction in exhaust gas systems.
Exhaust gas treatment bears many challenging problems at different scales. From the larger scale, where macroscopic flow through the monolith channels is of interest, down to the diffusive movement between and even inside the highly porous ceramic grains. Surely, completely different effects take place at each scale. Nevertheless, GeoDict simulates all those effects through different modeling and simulation modules.
At different scales and using various modules, we present some examples on how:
In essence, we show how GeoDict helps optimizing the catalytic and filtration efficiency....
CFD modelling of a bag filter plant for flue gas cleaning under consideration of flow shift and particle deposition relocations
U. Heck*, M. Becker, DHCAE Tools GmbH, Germany
Bag filter systems for exhaust gas purification are characterized by a large number of bag filters (usually over 1000), which are loaded with dust particles and cleaned at regular intervals with a pressurized medium. In plant operation, malfunctions often occur due to uneven loading of the filters, which leads to reduced service life with typically high repair costs and plant downtime.
In the problem at hand, a bag filter system for flue gas cleaning in a power plant operation showed several failures within one year, in which cracks occurred in the filter fabric of individual bags. As a result, the specifications for air pollution control could no longer be met. The plant had to be shut down frequently and defective filters had to be replaced.
In general, CFD analyses have proven their potential for optimizing various processes, especially in plant construction industries considering the relatively high investment and operating costs of the plants, but also to avoid plant failures. But the size of the bag filtration plant with the high amount of filters to be considered as well as the dynamic interactions between the continuous particle deposition on filters, the local increase in flow resistance at the filter and the associated flow and deposition displacement make it difficult to optimize the plants with typical flow simulation tools. Since common CFD tools cannot take these interactions between deposition, resistance increase and displacement into account, adapted calculation tools are required especially for these problems.
The CFD modelling was done using the filter modelling tool from DHCAE Tools based on the CFD toolbox OpenFOAM  . The modelling extension uses an Euler-Lagrangian approach whereby the interactions between filter loading, displacement of the continuous flow due to the increase in resistance and subsequent particle deposition are considered in an iterative process. This enabled the filters in the plant to be identified which receive a permanently increased particle load. As a result, these filters showed...
Test methods for indoor air cleaners with alternative test aerosols and considering ultrafine particles
S. Schumacher*, A. Banda Sanchez, A. Caspari, U. Schneiderwind, C. Asbach, Institute of Energy and Environmental Technology e.V. (IUTA), Gemany
In the light of the growing awareness for air pollution, indoor air cleaners are meanwhile widely used to improve the indoor air quality. The market is expected to continue growing strongly during the COVID-19 pandemic as air cleaners may contribute to minimizing infection risks by filtration of virus-carrying droplets. Up to now, there are various national standards to test indoor air cleaners that determine the clean air delivery rate (CADR) as a measure for the cleaning performance. In the light of developing the first international testing standard ISO/IEC 63086 for air cleaners, there is the chance to harmonize and complement the current test methods. In this context, this work deals with the choice of suitable test aerosols and methods for considering ultrafine particles.
Most of the national standards use cigarette smoke as test aerosol. However, the aerosol properties such as concentration, agglomerate size, particle morphology and charge state are expected to strongly depend on the combustion conditions. Furthermore, tobacco smoke is carcinogenic and cigarettes are comparably expensive. However, for introducing an alternative test material to an international standard, different aspects have to be considered. Primarily, the new method has to yield highly repeatable results that allow a comparison between the performances of different appliances. Secondly, it is important for the testing institutions that all materials are globally available at reasonable costs, are easy to handle without risks for the operator and the properties are independent of the supplier. Thirdly, for the manufacturers and consumers it is desirable that the results using the new test material do not strongly differ from the results from the previous national standards using other test materials. Although the latter is not a strict requirement, it may facilitate the introduction of the new test method and increase the acceptance by the consumers.
With this motivation, we investigated the performance of three air cleaners using different filtration technologies with respect to NaCl, KCl and DEHS and compared it to results derived with cigarette smoke. We show that the CADR can be very reproducibly measured with all investigated test aerosols and does not strongly depend on the choice of the material. This means that the filtration efficiency curves in the relevant particle size range are sufficiently flat and discharging effects by the test aerosol are negligible at the low exposures involved.
Concerning the particle size, recent national testing standards typically consider only particles larger than about 0.3 µm since considerably smaller particles are not accessible by optical particle counters. However, a test method considering smaller particles, especially in the ultrafine particle (UFP) size range <0.1 µm, is highly desirable for different reasons: Firstly, it is know that the relevance for health effects increases with decreasing particle size, since smaller can enter deeper the human respiratory system and have a higher surface to volume ratio. Furthermore, the largest fraction of the number size distribution of typical indoor aerosols lies in this size range and is thus most representative for real conditions. Finally, a previous study has shown that the efficiency of air cleaners can considerably degrade with decreasing particle size, especially when using of electret filters (Schumacher, 2018).
For these reasons, we investigated two different methods for determination of a CADR for UFP. As test aerosol, potassium chloride (KCl) particles were generated from an aqueous solution and dispersed in a 30 m³ test chamber, where the air cleaner was located. The first approach used a condensation particle counter (CPC) to measure the total concentration of particles larger than several nanometers, depending on the exact type of CPC used. By fitting the exponential decay curves with and without air cleaner, the CADR was derived. The method is easy to perform, but has the disadvantage that there is generally a dependence on the exact size distribution of the test aerosol. We investigated how large this effect is and how reproducibly size distributions can be generated by using different atomizers.
To circumvent the dependence on the particle size distribution, the CADR was alternatively determined by measuring the decay rates for monodisperse fractions in the UFP range using a differential mobility analyzer (DMA) adjusted to classify one certain particle size. As disadvantage, this restricts information on the cleaning performance to a specific particle size and has worse statistics because of the substantially lower particle concentrations. The results from both methods were evaluated and compared. The findings from the study shall drive the development of new methods in the recently published IEC 63086 testing standard for air cleaners...
Impact of roadside filtration devices on the concentration levels of road traffic pollutants at an urban traffic hotspot
T.K. Müller, T. Warth*, MANN+HUMMEL GmbH, Germany
In recent years, air quality in German cities has improved continuously, but hotspots in several cities still do not comply with the 2008/50/EC immission limit values. Currently, most exceedance events in Germany are related to NO₂ values being too high. In contrast, excessive particulate matter (PM) concentrations pose the greatest challenge from a worldwide perspective. A novel approach to locally improve the contaminant level is to employ outdoor air filtration devices, as e.g. the MANN+HUMMEL Filter Cube.
Stuttgart’s ‘Am Neckartor’ area is the most prominent air quality hotspot in Germany and therefor offers an ideal location for the exemplary investigation into the effectiveness of filtration devices at an urban traffic hotspot. As part of a public-private field testing project, 23 outdoor air filtration devices (MANN+HUMMEL Filter Cube) with a nominal flow rate of 14.500 m³/h per unit were installed in the ‘Am Neckartor’ area beside federal highway B14. The employed filters were equipped with high capacity activated carbon filter media capable of reducing the local NO2 and PM concentrations. The focus of this publication is set on the proof of concept investigations conducted at the Neckartor site...
Using ultrafine aerosols to understand service life of air filters for gas turbine applications
A. Corradi, G. Costa, Ahlstrom-Munksjö ; J. A. Marval Díaz, P. Tronville*, Politecnico di Torino, Italy
The concentration of airborne particulate pollution and the size distribution of the mass of the particles captured during air filters service life affect strongly how their airflow resistance changes throughout their operation. Therefore, the ageing process of air filters depends strongly on the place and on the system where they are employed. Urban and industrial areas are very challenging because of the high concentration of atmospheric sub-micrometer particles which clog fibrous filter media quickly. In fact, smaller particles get into the fibrous matrix (deep filtration) and occupy the space available among the fibers. Larger particles tend to deposit on the top of the filtering material (surface filtration) and increase much less its airflow resistance.
Depending of the type of filter material, natural ageing can show very different behaviors. For sure it is very useful to compare service life of filter elements in severe conditions. However, such testing programs should last six to twelve months to be meaningful and reliable. Moreover, the trend observed in data sets obtained during various years may differ because of the season or atmospheric conditions.
These considerations are relevant and of practical interest for most air filters and especially for those used in gas turbine air intake systems. In fact, their service life, maintenance costs and energy implications are strongly influenced by the type of airborne particulate pollution in a specific place and system. The availability of a repeatable and reproducible laboratory procedure to predict the natural ageing process, as closely as possible, is highly desirable. This procedure would allow to design and to optimize the filter media and the filter cartridge geometry, together with the combination of the most appropriate prefiltration choice.
For this reason, Ahlstrom-Munksjö and Politecnico di Torino carried out a research project to develop a new synthetic ultrafine aerosol able to clog a full scale filter element in laboratory in a few hours...
Novel method for removal of microplastics from various waters using organosilanes
M. Sturm, D. Schober, Wasser 3.0 gGmbH / abcr GmbH; K. Schuhen*, Wasser 3.0 gGmbH, Germany
Microplastics (MP) are ubiquitous in the aquatic environment and need to be removed. A new method uses organosilanes for the removal of MP from various waters. When organosilanes are added to water containing MP, they attach to the surface of the microplastics, collect it in agglomerates and fix it chemically. The trick is that MP agglomerates float on the surface and do not sink down to the ground. An easy separation with a skimmer leads to a reproducible MP removal efficiency of > 95% independent of polymer type and concentration.
To ensure the functionality of the process and to identify microplastics hotspots and sources, microplastics in the water needs to be quantified. Microplastics monitoring in waters with the common methods is very complex, time-consuming and expensive. Therefore, we developed a new approach to detect microplastics fast and inexpensive using fluorescent dyes. Those are selective for microplastics, which makes them easily detectable using a fluorescent imaging device.
According to circular economy, we are also looking for ways to reuse and recycle the microplastics agglomerates from the water. One promising approach is the use in concrete production. Another, but less favorable approach, is energy production.
Summarized, Wasser 3.0 applies a holistic concept for detection, removal, and reuse of microplastics from wastewater, industrial process water, seawater, and freshwater systems to combine environmental protection, sustainability, and resource efficiency...
Investigations on the process strategy of aqueous two-phase flotation (ATPF)
L. Jakob*, M. Heinzmann, H. Nirschl, Karlsruhe Institute of Technology (KIT), Germany
The purification of industrial enzymes from complex biosuspensions represents a major challenge for the bioprocess. Many separation steps are necessary to capture the target protein from the fermentation broth and to increase the purity up to the final product. Losses and energy costs of the individual steps sum up and purification costs for enzymes usually represent more than 50% of production costs.
Flotation of enzymes in aqueous two-phase systems (aqueous two-phase flotation, ATPF) combines selectivity of extraction with high mass transfer of flotation. Proteins attach themselves with their hydrophobic part to rising bubbles and are transported from bottom into top phase. This allows to perform "Capture" and "Clean" in one step. ATPF promises to be an efficient alternative to conventional purification processes of biotechnological products by eliminating several separation steps, warranting mild conditions and high product concentration in an aqueous top phase. However, more research is needed to develop the new technology on its way to an industrial use.
Especially the process design needs to be investigated. Looking on common foam separation techniques for bio-products, a cylindrical flotation cell might be preferred for ATPF as well. During a long ascent during bottom phase the bubbles might collect more target molecules and transfer them into top phase of the aqueous two-phase system. On the contrary a horizontal flotation tank, like used in mineral flotation, would provide high throughput and should be preferred for continuous flotation.
In this talk, fundamental perceptions how an optimized ATPF-process should be realized will be presented...
Microscale modelling and simulation of the removal of water from diesel fuel using hydrophobic separator meshes
S. Antonyuk, Technische Universität Kaiserslautern; O. Elsayed*, R. Kirsch, S. Osterroth, Fraunhofer Institute for Industrial Mathematics (ITWM), Germany
Liquid-liquid separation systems are vital for many applications: power generators, automotive, hydraulic lines, etc. In the special case of diesel fuel, the trend towards sustainable fuel production and reduction of hazardous emissions lead to the increasing usage of ultra-low-sulfur diesel and bio-diesel. Such fuels exhibit a significantly reduced the surface tension between the diesel and the inevitable water content, rendering the removal of the water more difficult. Consequently, the design of separators in diesel fuel filters meeting today’s performance requirements imposes a challenge to the developing engineer and suitable simulation techniques. Hence, in order to improve and further optimize the current separator systems, a better understanding of the influence of material parameters such as wettability and geometric properties of the mesh on the separation performance would be very useful.
The challenge in modeling and simulation of such systems is the fact that phenomena on different length scales influence each other:
On the microscale, individual droplets are considered. In the free flow region, they are much smaller than the hydrodynamic length scale and their motion is mainly due to the flow. After coalescence at the hydrophobic separator screen, gravitational forces are more and more dominant and separation by drainage occurs. Both coalescence and drainage influence how much of the mesh surface is open. On the macroscopic scale, this affects the over-all differential pressure and the distribution of the local flow speed near the mesh, which in turn changes the transport of the water droplets towards the mesh.
The present work is devoted to the modeling and simulation of the interaction between the water droplets and the separator screen taking into account the gravity forces in the microscale. It is seen that...
Characterization of suspensions and emulsions by means of multiwavelength reflectance and machine learning methods
S. Boldt*, D. Lerche, LUM GmbH; P. Menesklou, O. Zhai, H. Nirschl, Karlsruhe Institute of Technology (KIT), Germany
Sedimentation of bidisperse polymer suspensions in aqueous polymer solutions
T. Sobisch, U. Schuldt, D. Lerche*, LUM GmbH, Germany
Basically, separation processes can be described by extended Stokes law taking into account volume concentration of disperse phase (hindrance) and rheological behaviour of continuous phase. To deduce separation behaviour under high gravity in centrifuges one can assume that separation velocity scales linearly with acceleration in Newtonian liquids. Situation in non-Newtonian liquids is much more complex, however, this is often characteristic for industrial separation tasks, e.g. during downstream bioprocessing. Modelling of the separation processes gets even more complicated when taking into account polydispersity of real-world suspensions.
To contribute to a better understanding, model investigations were performed with monodisperse polymer particles (6 and 15 µm) and their bidisperse mixtures in aqueous solutions of carboxmethyl cellulose (CMC). Measurements were conducted as function of centrifugal acceleration and at gravity...
3D information about the multiphase processes in the pore space of a filter cake using X-ray tomography
E. Löwer*, T. Leißner, U.A. Peuker, Technical University Bergakademie Freiberg, Germany
Predicting the dewatering of porous structures is the key to evaluate the efficiency of mechanical solid-liquid separations: The investigation of the developing liquid distribution and the characterization of the saturation process usually requires experimental data/support points. Direct computed tomographic insights into the structure of the filter cake allow the tracking of micro processes during the desaturation process. The used ZEISS Xradia 510 Versa X-ray microscope used combines classic X-ray tomography with microscopy optics, which makes significantly smaller imaging voxel sizes possible.
The investigated geometric filter cake properties depend mostly on the distributed particle properties, which are deterministically coupled to each other. Typical technically relevant size distributions (narrow monomodal, logarithmic normal distribution or bi-modal distributed particle sizes) are investigated in 2D and 3D analyses of the individual particles (size, shape) and in tomographic characterization of the resulting filter cake. The size range of the particles is selected under the condition that the weight force remains the dominant size with respect to the interaction forces of the particles (x10 > 20 µm). The structural information about the pore system is systematically evaluated and quantified by characteristic parameters (integral and local porosity, horizontal and vertical pore radius, coordination number, pore connectivity, tortuosity, local contact angle) of the system.
In addition to the completely saturated cake structures, the mentioned parameters are also determined on dewatered filter cakes...
Membrane distillation for the production of pharmaceutical-grade water
C. Nellessen*, T. Klein, Wilhelm Werner GmbH; H.-J. Rapp, DEUKUM GmbH; F. Rögener, Technical University Cologne, Germany
The water used for pharmaceutical applications is subject to strict regulations. Water quality as well as processing measures are clearly defined. In the European Union, the quality of water for pharmaceutical use is determined by the European Pharmacopeia (Ph.Eur.). Within the current pharmacopoeias, a distinction is made between purified water (PW) and water for injection (WFI) [EU2017].
PW is used for the production of medical products that are neither pyrogen-free nor sterile. Pyrogens are substances that cause fever in humans during parenteral intake (bypassing the intestine, e.g. intravenously). WFI is water for the production of medical products, solutions and dilutions for parenteral use. Drinking water is the raw material for both, PW and WFI production according to the respective national regulations [EU2017].
The Ph. Eur. sets limits and requirements for the quality of PW and WFI. Some parameters are depicted in Table 1....
Membrane distillation (MD) is investigated worldwide as a low cost, energy saving alternative to conventional separation processes such as distillation and reverse osmosis (RO). The porous and hydrophobic membranes used in MD processes allow the passage of vapors only and retain all nonvolatile components and liquids on the retentate side, thus the product obtained is theoretically 100% pure water vapor. Therefore, it is important that the dry pores must not be wetted by the liquid feed, which is directly in contact with the membrane. Due to the low required temperature level, the use of waste heat as well as solar thermal energy and geothermal energy is possible for the MD.
MD processes can be categorized into four basic module configurations, which play a fundamental role in separation efficiency and processing cost: direct contact membrane distillation (DCMD), air gap membrane distillation (AGMD), sweeping gas membrane distillation (SGMD), and vacuum membrane distillation (VMD).
A MD test plant was build up in the technology center of Wilhelm Werner Reinstwassertechnik GmbH, using membrane modules in AGMD configuration provided by DEUKUM GmbH. The condensate runs out of the module through gravity at the bottom. Different membranes were investigated. First results show that...
Nanofiltration versus reverse osmosis for brackish water desalination process considering wide range of salinity: pilot scale investigation
H. Dach*, M. Pontié, Angers University, France; A. Lhassani, Fez University, Morocco
The most commonly used technology for brackish water desalination is Reverse Osmosis (RO), due to its lower energy consumption. Newer generation membranes, such as Nanofiltration (NF) and ultra-low pressure Reverse Osmosis (ULPRO) membranes may provide the opportunity to reduce feed pressures and operating costs associated with RO desalination while providing similar permeate water quality. Since NF membranes are supplied in the same configurations as RO membranes, utilities could replace RO with NF spiral-wound elements without the need for significant additional capital investment. In this study, the tradeoffs in choosing NF and ULPRO membranes over RO were investigated including whether or not significantly lowering operating pressures/costs would result in diminished permeate water quality...
Possibilities for increasing the efficiency of decentralized production of potable water from seawater using membrane processes
T. Peters*, Membrane Consulting, Germany
Increasing demand for water resources is straining available supplies to an unprecedented degree, sparking the emergence of many innovative technologies for enhancing the efficiency of i. a. pressure driven membrane processes.
For more than five decades there has been remarkable growth in the need for quality water purification by all categories of users. The increasingly broad range of requirements for water quality has motivated the water treatment industry to refine existing techniques, combine methods and explore new water purification technologies.
Although great improvements have been made, misconceptions still exist. Therefore, it is necessary to increase the understanding of the capabilities of available technologies and how these technologies might be applied. Thereby it has to be considered that in principle and by experience there are no two water treatment problems exactly alike. There will always be slight differences with more than one technically acceptable and scientifically-sound solution to any given water treatment problem. As guideline shall be considered “each case is different”.
Based on activities and involvement of the author in seawater desalination in the last 40+ years with focus on optimization and improvement of seawater reverse osmosis desalination plants it can be stated, that actually sustainable, environmental sound and cost saving solutions, that are familiar to real experts in this market, often are not considered by potential user as it should be or could be. This applies mainly to the areas „seawater intake and pre-treatment“, „pumping and energy saving devices“ in combination with renewable energy sources at e. g. off-grid situations, „post-treatment“ (mineralization), „brine mining” and “machine learning (ML)” as part of Artificial Intelligence (AI) for optimizing the control of the function of desalination plants.
Facing the actual situation and the future demand, the user of such plants should obtain “best of the best” solutions if arguments as “cost saving”, “long-term sustainability” and “environmental sound” are of importance. Thereby the success achieved at centralized huge seawater reverse osmosis desalination plants should be adapted as far as possible to decentralized and small plants in order to increase the resource efficiency and to reduce the related carbon footprint during manufacturing, commissioning and operation of such units.
Selected example for such solutions for decentralized plants will be presented...
12:00 h - Lunch
Day: 10 March 2022
Time: 13:00 - 14:15 h
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Characterization of deposited oil structures on thin, porous oil mist filter media applying µ-CT imaging
C. Straube*, J. Meyer, A. Dittler, Karlsruhe Institute of Technology (KIT), Germany
Fibrous coalescence filters are widely applied in gas cleaning processes to separate liquid droplets from a gas flow (e.g. oil mist). When separated on the fibres of the filter medium, the oil droplets can take many shapes dependent on the wettability, roughness and diameter of the fibres, droplet volume and fibre arrangement (e.g. axisymmetric barrel-shaped droplets and axially asymmetric clamshell-shaped droplets). The overall morphology of the deposited droplets on the filter fibres is well known from optical microscopy, however, no studies exist regarding the impact of these separated droplets within the filter matrix on the separation efficiency. To investigate a change in the filtration efficiency the exact morphology of oil structures on and between adjacent filter fibres has to be characterised. Thus, the spatial deposition of the droplets on the fibres (upstream, downstream or partially upstream and downstream side) as well as...
Comparing mesh-based and voxel-based CFD models for aerosol deposition in complex fibrous filters
D. Hoch*, A. Baumann, J. Behringer, J. Niessner, Heilbronn University of Applied Sciences; M. Azimian, Math2Market GmbH, Germany
Today, liquid aerosols are generated in many industrial processes like machining, manufacturing of catalysts or in pneumatic compressors. Liquid aerosols may be harmful since small droplet may enter the respiratory system and cause lung cancer, allergies, or other diseases. Also, due to the recent COVID-19 outbreak, aerosols containing viruses are classified as dangerous. We present results of micro-scale simulations of mist deposition on fibrous structures and validate them by comparison to single fiber efficiency (SFE) theory and to experimental data...
On the performance enhancement of fibrous filter for removal of oil mist droplets
F. Chen*, Q. Ba, W. Yu, Z. Ji, China University of Petroleum, China
Oil mist coalescence filtration is widely used in process industry. Efficient removal of micro droplets and enhancement of filtration performance of filter media are the focus of attention at present. In this work, different methods were used to modify the traditional filter materials for oleophilic (dry and wet) and oleophobic (dry and wet) treatment. The effects of the modification methods on the coalescence filtration performance and surface liquid distribution of the filter media were studied, and the optimal performance enhancement method for liquid aerosol separation with high efficiency and low resistance was proposed. The results show that...
Topology optimization of gas-particle filters using an adjoint solver
N. Jüngling*, T. Gaugler, J. Pospichl, J. Niessner, Heilbronn University of Applied Sciences, Germany
Conventional filters consist of one or more filter layers, which are either woven or composed of tangled fibers. The quality of the separation results almost only from density of the fiber arrangement. Due to the manufacturing process, compromises between separation and pressure loss that are in the opposite relationship to each other are inevitable.
The development of additive manufacturing has made great progresses in recent years. Using this technology, filter manufacturing is no longer restricted to conventional methods. At this point, the adjoint topology optimization of filters is a promising alternative opportunity of filter development. The idea behind this is to use the adjoint solver to generate geometries that have been optimized with regard to pressure loss and the filtration efficiency. The complex non-linear relationships between the separation mechanisms and the pressure drop offer the opportunity for improvement. The fluid region with the CAD model of the initial geometry is divided into volume cells. The cells at the fibers are then varied by mesh deformation until an optimum is found. Using the often bionic-looking optimized structures physical prototypes are generated using additive manufacturing. In a further process step the structure is coated and thus, functionalized. The new approach offers the chance to develop filters in a new way, avoiding the previous parametric development and even crossing the Pareto front in the multi-objective optimization of filtration efficiency and pressure loss.
The key to topology-optimized "bionic" filters are...
Prediction of the filtration performance for submicron aerosol particles using deep neural networks
M. Kerner*, R. Hesse, S. Antonyuk, Technische Universität Kaiserslautern, Germany
Nonwovens are commonly used in aerosol filtration to remove particles from gases. The nonwovens can differ, for example, in fiber diameter (distribution), porosity, thickness and grammage, which affect air permeability and filtration performance. In conventional nonwovens, the particles are deposited by the mechanical deposition mechanisms (diffusion, impaction and interception). The fibrous structure can also be electrostatically charged (electret nonwovens). In addition to the mechanical deposition mechanisms, charged particles are deposited by the Coulomb effect and any (charged or uncharged) particles by dielectrophoresis. This increases filtration performance while maintaining air permeability.
This allows a wide range of variation in the development and selection of suitable nonwovens for the desired application. Accordingly, experimental investigations can be performed using existing or specially manufactured nonwovens. However, experiments are time-consuming, so that more or less complex model calculations appear useful. Empirical models or formulas are not sufficient for complex three dimensional structures as nonwovens, since they are based on single fiber theories. Numerical simulations are more suitable, although the computational power is high for fiber diameters in the submicron and nanometer size range.
In this work, a new and time-optimized approach for predicting filtration performance based on machine learning (LeCun et al. 2015, Nature) is established. For a first...
Evaluation of aerosolized MS2 bacteriophages inactivation using activated carbon fiber (ACF)
Y.L. Jang*, J.S. Heo, D. Park, Korea Railroad Research Institute, Korea
Infectious diseases occur by spreading into the air through particulate matter (PM) and droplets containing viruses. To prevent the virus transmission in the air, research on inactivation of floating viruses is needed. In this study, we examined inactivation characteristics of MS2 bacteriophages according to the thickness of Activated Carbon Fiber (ACF). ACF is a material processed in the form of fibers to improve the adsorption performance of activated carbon, which has a high performance on the removal of gaseous and particulate matter. In, the effects of inactivation MS2 bacteriophages was examined by comparing before and after passing the ACF. The experimental results showed that...
Metris addIQ RheoScan AI – real-time, automatic adjustment of polymer with the use of Artificial Intelligence
S. Peter*, M. Karner, ANDRITZ AG, Austria
ANDRITZ is paving the way for sustainable improvements in the availability, productivity and quality of solid/liquid separation processes by leveraging advances in digitalization and IIoT. One excellent illustration of this process-focused innovation is RheoScan, which draws on Artificial Intelligence (AI) to achieve measurable savings in terms of investment and operating costs.
Sludge thickening and dewatering processes require the injection of polymer as flocculants, necessary to allow solid/liquid separation by filtration. But polymer can be pricey in terms of running costs and environmental impact. In traditional set-ups, the initial polymer dose is selected by the machine operator and rarely adjusted throughout the day, regardless of changes in the sludge characteristics or production needs.
Metris addIQ RheoScan, the first optical measurement system on the market, applies an intelligent camera system that detects the clear belt area and actual sludge viscosity during the thickening and dewatering process. With support of AI, Metris addIQ RheoScan ensures that the thickening and dewatering equipment always uses the optimum dose of polymer. It automatically adjusts and optimizes the polymer dose 24/7 and provides maximum flexibility to control and monitor the entire operation remotely, eliminating the need for on-site supervision.
The results of case studies in environmental and mining applications...
Floc characterization with turbiscan apparatus: Which useful information for sludge thichening and dewatering?
P. Ginisty*, I. Igwet, IFTS - Institute of Filtration & Techniques of Separation; R. Ramsch, Formulaction, France
Sludge is produced by wastewater treatment and is in the form of a liquid slurry with a water content of 95-99% and the is treated (treatment principle represented by the figure below) to be compatible with its final destination (use in agriculture, incineration, landfilling…)
Effectiveness and cost of sludge treatment and disposal operations are strongly affected by its volume, so reduction of volume is certainly a pillar for the development of sustainable management systems. To this purpose, thickening and dewatering are the necessary steps to improve sludge solids concentration and most of these operations require flocculation pretreatment to obtain an efficient separation process between water and solids.
Treatment optimization is very empirical as operators should continuously adapt the machines performances to sludge and flocs properties and variations of these properties over time. If some methods are classically used for sludge characterization, relatively few are available for flocs and levels of knowledge of flocs behavior remains low. It is necessary to take into account the water release from flocs, depending of the constraints in the mechanical dewatering machines. Only free water, sum of the supernatant water and bulk water, respectively present between and inside the flocs can be removed by mechanical processes but flocculation can modify the ratio between free and bound water .
Laboratory methods and devices should be tested to get more knowledge about flocs properties and behavior, too help the selection of polymers and corresponding dosage and to collect data about their dewaterability. Among them, drainage and CST tests vs mixing time, basket spin tests with shearing, limit dryness determination can give useful information . It is also necessary to take into account how the way of floc formation can influence their properties.
This paper presents flocs characterization by Turbiscan apparatus. Its allows detection at an early stage all kinds of destabilisation such flocculation, sedimentation, coalescence… 20 to 50 times faster than the visual detection. The Turbiscan works on...
Compressibility in filter aid filtration with cellulose depending on the loading
D. Neuber*, U.A. Peuker, Technical University Bergakademie Freiberg, Germany
Filter aid filtration, also known as precoat filtration, is used to separate very small, colloidal or gelatinous impurities from a generally low–concentrated suspension. It is a very flexible application in solid-liquid separation due to the wide range of available filter aids with different particle sizes and modifications. The aim of using filter aids is building up a stable permeable network in which submicron particles can be separated from the liquid to gain a particle–free filtrate. The most commonly used filter aids in industry are kieselguhr, perlite and cellulose, which each have their own advantages and disadvantages depending on the field of application, due to their different structure and origin.
Kieselguhr, fossil skeletons of diatoms, builds up a very stable filter cake, has a large surface area and there is a great wealth of experience in handling it. In comparison, cellulose is a renewable resource, no threat to health, and better disposable, but forms a significantly more compressible filter cake. This leads to a porosity change over the cake height and mainly to a decrease in porosity in the lower filter layers close to the filter medium. The pores are getting narrower, leading to higher flow velocities and higher shear rates. Separated solid particles can remobilise again and re-enter into filtrate. Such redispersion negatively affects the process behaviour of the precoat filtration. For optimization of filter aid filtration processes with cellulose, these effects of compression need to be investigated.
In this work, the compression behaviour of cellulose filter cakes depending on titanium dioxide loading is investigated by using a Compression-Permeability-Cell. The results show...
Steam pressure filtration - Combination of water insoluble liquids and dewatering with steam
S. Esser*, U.A. Peuker, Technical University Bergakademie Freiberg, Germany
Steam pressure filtration (SPF) has been established in the field of solid-liquid separation for the last 20 years, while the field of application is steadily expanding. The treatment of solvent-loaded solids, e.g. following a solid-liquid extraction presents a challenge in practice. This challenge becomes even more complicated if the solvents used are volatile organic compounds (VOC) which are poorly soluble in water and thus bio-incompatible. A complete mechanical separation of the VOC from the solid is not possible and a following drying process is usually energy intensive and expensive.
In comparison with conventional filtration, in SPF the saturated filter cake is treated with saturated or superheated steam instead of gas, which results in excellent washing and dewatering behaviour of the filter cake.
Due to the uniform mechanical displacement of the suspension liquid, the SPF promises a lower residual VOC load of the filter cake in contrast to conventional filtration at the end of the mechanical displacement phase. The end of mechanical displacement is defined as the time of steam breakthrough in SPF or gas breakthrough in conventional filtration.
The filtrate accumulated up to these times is pure VOC in both processes. Another steam flow through the filter cake, which in this context can also be seen as steam stripping, further reduces the VOC load of the filter cake. The driving force here is the minimization of the thermodynamic potential to the thermic equilibrium. The energy required to evaporate the VOC is supplied by the vapor phase in form of enthalpy of vaporization of water condensing on the particle surface. In this process phase, the filtrate is collected as a two-phase mixture of VOC and water according to the vapor composition at the outlet of the filter.
The investigations on SPF in combination with a water-insoluble liquid phase were carried out in the context of the already completed AiF project IGF 19305 BR. The presentation gives an overview on the project and a summary of the results....
Modelling packed bed structures
W.L. Eales*, C. J. Price, P.A. Mulheran, University of Strathclyde, UK
Agglomeration is an issue that causes many problems during secondary processing of pharmaceuticals, requiring material to need further processing and thus costing additional time and resources to ensure a satisfactory outcome. A potential source of agglomeration is the particle contact established during filtration, leading to robust agglomerates forming during drying when these contacts are cemented in place with precipitating material. Here we present a two-dimensional model for the formation of packed bed structures during filtration, in order to better understand the distribution and properties of the inter-particle contacts. The model uses circular particles of different sizes, mimicking bimodal particle size distributions often encountered in practice. The statistics of packing and void formation, along with the distribution of inter-particle contacts, are presented and discussed in the context of filtration and drying. The model paves the way for predictive capabilities that can lead to the rational design of processing steps that minimise the impact of agglomeration.
The model simulates circular particles of different radius falling from the top of the box to the bottom, as if settling under gravity or in a gentle solvent flow. Once a particle impacts the bed, it then moves across the bed surface until a position of stability is found where it is positioned to rest on top of other particles. This repeats until the box is full or a predetermined number of particles have been placed.Figure 1 shows...
1½-Way CFD-DEM coupling with DNSlab: The optimal compromise between modeling depth and computer resources demand for the 3D simulation of microscale fluid-particle-processes
K. Schmidt*, IT for Engineering (it4e) GmbH; V. Puderbach, S. Antonyuk, Technische Universität Kaiserslautern, Germany
Microscale fluid-particle processes, especially such as filtration of solid particles from liquid by porous media, involve the effect of the fluid flow on the particles as well as the effect of the particles on the fluid flow. For the simulation of such processes, where the CFD method is used to model the fluid flow and the DEM method to model particle-particle and particle-structure interactions, several approaches of coupling these two methods can be applied with different modelling depths and demands regarding computer resources. Using the it4e simulation software DNSlab, different variants of coupling the CFD and the DEM method have been implemented and evaluated regarding their suitability especially for microscale fluid-particle processes...
Removal of pharmaceuticals from aqueous solutions using hybrid ceramic membranes
J. Radeva*, A.G. Roth, C. Göbbert, Nanostone Water GmbH; R. Niestroj-Pahl, L. Dähne, Surflay Nanotec GmbH; J. Wiese, University of Applied Science Magdeburg, Germany
In the presented study the technological advantages of ceramic filtration elements were combined with polyelectrolyte films in the development of hybrid membrane for elimination of pharmaceuticals from aqueous solutions. Standard alumina ultrafiltration ceramic membranes were coated with nanosized polyelectrolyte films using Layer-by-Layer technology. The polyelectrolyte chains form a network with nano-pores on the ceramic surface. This enables the retention of small molecules like pharmaceuticals and microplastics even with standard ultrafiltration filter. Additionally, the polyelectrolyte coating provides the possibility for repulsion of contaminant’s molecules with opposite charge due to its adjustable Zeta Potential.
Properties like permeability, bubble point, pore size distribution and Zeta Potential of the ceramic and hybrid membranes were characterized using various laboratory and pilot tests. The main focus of the present study was the filtration behavior investigation of the hybrid membranes...
ZIF-8/GO/PIM-1 thin film nanocomposite membrane for butanol/water separations by pervaporation
B. Qiu*, X. Fan, P. Budd, A. Foster, University of Manchester, UK; P. Gorgojo, Zaragoza University, Spain
Membranes to recover organic compounds from dilute aqueous solutions are desired for application such as biobutanol production. Among them, membranes of the polymer of intrinsic microporosity PIM-1, with unique rigid and contorted ladder-like backbone, have outstanding permeability and high selectivity as compared to the more conventional glassy polymer membranes. Freestanding polymeric membranes of several tens of microns are typically prepared at lab scale for pervaporation (PV), and thin film composite (TFC) membranes are the preferred configuration for industrial PV applications as they can provide high flux, while maintaining a good mechanical stability. However, the infiltration of the PIM-1 into the porous substrate during the coating process used for their fabrication can lead to a higher effective thickness of the active layer and reduce the permeate flux. In an attempt to avoid penetration...
Bilayer composite membranes: fabrication and optimization for improved gas permeability
S. Farrukh*, F. Yousaf, National University of Sciences & Technology (NUST), Pakistan; X. Fan, University of Edinburgh, UK
Membranes with high gas permeability are greatly attractive to both academia and industry. As single layer dense membranes are being utilized in industries for separation and purification of gases such as CO2, CH4 and N2. The selectivity of these membranes is good and depends on polymer selection. However, the permeability of single layer dense membranes is very low. According to Robeson’s curve, selectivity and permeability of gases have inverse relationship. To address this point, composite membranes with superior performance can be employed for CO2 separation from CH4 and N2. Herein, we report comparison between high performance composite membranes of Cellulose acetate (CA)/ γ-CD(Cyclodextrin)MOF and Polyurethane(PU)/γ-CD-MOF supported on a porous structure of Poly vinyl alcohol (PVA). Fourier Transform Infra-Red spectroscopy was used to study the existence of different functional groups in the membranes. The presence of γ-CD-MOF in the membranes was also confirmed by X-Ray Diffraction. Universal Testing Machine was used to determine the maximum tensile strength of the prepared membranes. Scanning Electron Microscopy shows good dispersion of γ-CD-MOF and it also displays defect free selective and porous layers. The resultant membranes show excellent...
Day: 10 March 2022
Time: 14:45 - 16:00 h
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Modeling and simulation of coalescence in the context of oil mist filtration using a distance map
D. Hoch*, A. Weber, J. Niessner, Heilbronn University of Applied Sciences, Germany
Today aerosols are produced in many industrial processes like machining or in pneumatic compressors. The harmfulness of these industrially produced droplets often lies in the liquid itself as it can be toxic or cancerous while exhaled natural aerosols can carry viruses or other pathogens. For health protection, the filtration of these aerosols is an important task. The wetting properties of the fibers have a large influence on the filtration efficiency and coalescence of droplets on the fibers. Oleophilic fibers are better in capturing the oil aerosols while the drainage increases with oleophobic fibers. For improved efficiency and drainage properties, a mixed-wet fiber system could therefore be advantageous.
Deposition of droplets and the resulting coalescence is highly complex and extremely dependent on the wetting properties. Describing these processes in filter-scale simulations is computationally extremely demanding, if not infeasible. We present a new approach for simulating oil mist deposition and droplet coalescence correctly accounting for the wettability of the fibers, especially for mixed-wet filter media. The aim is to gain a more realistic pressure loss of a fibrous filter structure which takes the presence of the filtered phase into account as well as the coalescence of the liquid phase on the fibers depending on the wettability and the fluid parameters...
Profiled bicomponent filaments for oil mist filter media
L. Beek*, A. Becker, T. Gries*, RWTH Aachen University, Germany
Liquid aerosols endanger human health if their concentration in the air is too high or if people are exposed to them for too long. In the industrial sector, oil mist can cause severe lung diseases in workers. Therefore, coalescing filters are used for air purification. The use of filters results in a pressure loss of 2 – 5 % at the filter medium and residual emissions of more than 20,000 particles/m³. There is a conflict of objectives between a low pressure drop and a high degree of separation. In addition, clogging due to oil occurs quickly inside the filter media.
Therefore, a novel fiber for coalescing filters is presented in this paper...
Filtration performance of compressed coalescing fibrous media
C. Chang*, C. Linghu, Z. Ji, China University of Petroleum, China
Fibrous materials are subjected to compression in many industrial processes, such as natural gas filtration at high pressures. A number of investigations have been conducted to study the relationship among compression load, pore size and permeability. However, the effect of structural parameters on the filtration performance of compressed media has not been reported.
In our study, the variation of packing density, pore size distribution and contact angle for both oleophilic and oleophobic glass fibrous materials with different degrees of compression were experimentally measured. Furthermore, the filtration performance of compressed filters such as wet pressure drop, penetration, saturation, and liquid distribution are investigated.
The results showed that...
Charged PVDF multilayer nanofiber filter in filtering simulated airborne novel coronavirus covid-19 using ambient nanoaerosols
W.W.-F. Leung*, The Hong Kong Polytechnic University, China
The novel coronavirus (COVID-19), average size 100 nm, can be aerosolized by cough, sneeze, speech, and breath of infected persons. The airborne carrier for the COVID-19 can be tiny droplets and particulates from infected person, fine suspended mists (humidity) in air, or ambient aerosols in air. To-date, unfortunately there are no test standards for nano-aerosols (≤100 nm). A goal in our study is to develop air filters (e.g., respirator, facemask, ventilator, medical breathing filter/system) with 90% capture on 100-nm airborne COVID-19 with pressure drop of less than 30 Pa (3.1 mm water). There are two challenges. First, this airborne bio-nanoaerosol (combined virus and carrier) is amorphous unlike cubic NaCl crystals. Second, unlike standard laboratory tests on NaCl and test oil (DOP) droplets, these polydispersed aerosols all challenge the filter simultaneously and they are of different sizes and can interact among themselves complicating the filtration process. For the first time, we have studied these two effects using ambient aerosols (simulating the bio-nanoaerosols of coronavirus plus carrier of different shapes and sizes) to challenge electrostatically charged multilayer/multimodule nanofiber filters...
Research on the development of materials for removing airborne pathogens using low-temperature plasma
S. Lee*, J.-Y. Park, K.-H. Baek, S.-J. Kim, J.-H. Choi, J.-H. Ha, H.-H. Park, Korea Institute of Materials Science (KIMS), Korea
As the management of airborne pathogens in the indoor air has emerged due to the COVID-19 pandemic, active quarantine technologies using air conditioning systems are being developed. Since 2019, the Korea Institute of Materials Science has been actively developing material parts that can effectively trap and sterilize or inactivate pathogens such as bacteria and viruses floating in indoor air. We developed a low-temperature plasma filter that physically traps pathogen particles and sterilizes or inactivates pathogens with ozone, which has strong oxidation potential. A low-temperature plasma filter uses a ceramic foam with pores of several tens of micrometers, which simultaneously acts as a dielectric for plasma generation and as a filter for collecting pathogens. The currently developed low-temperature plasma filter has a size of 100 cm2 and generates ozone at a level of 0.5 ppmv at a wind speed of 1 m/s to oxidize captured pathogens. The catalyst located at the rear end of the low-temperature plasma filter reduces the emitted ozone to a level of...
A study of copper fiber type ionizer to inactivate aerosolized viruses
J. S. Heo*, Y.L. Jang, D. Park, Korea Railroad Research Institute, Korea
A matter that threaten health are increasing due to deterioration of air quality. Among, bio-aerosols and fine particulates are the main causes of air quality deterioration. There are two methods for reducing such particulate matter: a fiber filter method or an electrostatic precipitation method. However, due to the characteristics of microbes, they can survive for long period of time and changing these filters improperly could lead to the transmission of pathogenic bacteria or virus, and even to outbreaks. In addition, the existing electrostatic precipitation method has a problem in that ozone is generated. In this study, a copper fiber type ionizer that operate at low voltage to reduce ozone generation and inactivate viruses using antibacterial properties was studied...
Development of membrane-woven-composite filter media for continuous cake filtration without gas throughput
N. Benz*, P. Lösch, S. Antonyuk, Technische Universität Kaiserslautern, Germany
Filter cakes resulting from the filtration of concentrated suspensions in continuously operating filters are often dried thermally afterwards to obtain the dry product. This is the most expensive process step. Mechanical dewatering can significantly reduce the moisture in the filter cake and thus the energy required for thermal drying. The result is significant cost savings. In gas differential pressure dewatering, the liquid present in the pore system of the filter cake is removed after overcoming the inlet capillary pressure. As can be seen in the figure on the left, the emptied pores of the filter cake lead to an undesired gas throughput. This has economic and technical disadvantages, because the gas throughput has to be compensated by the vacuum pump. The result is higher energy costs , . In this contribution, the developed filter media is presented which can avoid gas throughput during cake dewatering. A combination of a woven filter cloth and a microporous membrane is used for this purpose. Due to the microporous properties of the membrane, the conditions for gas throughput-free cake filtration are given. The membrane capillary pressure is higher than usual differential pressures for filter cake dewatering. Therefore, liquid can be removed from the filter cake but not from the membrane pores. The result is a gas throughput-free cake filtration, as can be seen in the figure on the right. The focus of this work is on the systematic investigation of a highly stressable connection between filter cloth and membrane...
Roller discharge of pasty filter cakes on drum filters - Influence of the particle system
V. Bächle*, M. Gleiß, H. Nirschl, Karlsruhe Institute of Technology (KIT), Germany
The filtration of organic particles is increasingly becoming the focus of science. Organic single-celled organisms such as microalgae or yeast are an efficient supplier of important proteins, unsaturated fatty acids, oils, colourants and vitamins. They are therefore interesting raw materials in the food, chemical, bioindustry and pharmaceutical sectors. One disadvantage is still the comparatively high harvesting costs. These are caused by a high compressibility of the organic microparticles, which considerably reduces the filtrate flow. Increasing the pressure, for example via centrifugation, is also uneconomical due to the additional acceleration of the considerable water content. As a possible economical continuous option, thin film filtration of small cake heights (< 1 mm) on drum filters offers a process with which the pressure loss across the filter cake can be kept constantly low. Thin film filtration is based on the formation of a thin filter cake with immediate decrease after dehumidification. However, the removal of pasty thin filter cakes remains a challenging process. Due to the cake heights of < 1 mm, the risk of damaging the filter medium is high with the commonly removal via scrape. Therefore, an alternative cake discharge via a roller is used. According to the current state of research, an effective prediction of the cake removal behaviour and fouling of the membrane is not possible for thin film filtration.
In the context of this study, the influences of an inorganic particle system (titanium dioxide) and a biological particle system (yeast) are shown...
Innovative filter module to separate microplastics from wastewater
A. Lanfermann*, T. Barthels, M. Nießen, P. Abels, Fraunhofer Institute for Laser Technology ILT; G. Klass, C. Doisl, Klass-Filter GmbH; C. Riester, LaserJob GmbH; B. Hoche, Lunovu GmbH; T.Q. Pham, OptiY GmbH, Germany
The pollution by microplastics is currently a major topic in the society. Microplastics are defined as plastic particles with a diameter < 5 mm. They are divided into primary microplastics, deliberately introduced particles in e.g. shower gels or soap, and secondary microplastics, e.g. plastic bags dissolved by UV light. Both types of microplastics get in our wastewater and later in the wastewater treatment plants (WWTPs). Bigger particles can be separated reliably in the WWTPs but small particles < 63 µm are not filtered and are released in our rivers and seas. But exactly these small particles are the dangerous ones for our flora and fauna because they accumulate in the tissues of humans, animals and plants as well as in the soil. This fact makes it necessary to develop better filter systems to separate even particles < 63 µm out of wastewater.
The project aims to develop a filter to separate microplastic particles down to 10 µm from wastewater. The basis of this filter is the Klass cyclone filter that has an actual pore size of 100 µm and is used in different cleaning processes for wastewater and canal water. To adapt this cyclone filter to the challenge of filtrate microplastics, the project team develops a new filter insert with pore sizes of 10 µm. At the end of the project a prototype will be built and tested in a WWTP to evaluate the function of the filter. The new developed filter insert consists of...
Electrodewatering of different sewage sludges under constant electric current: impact of physico-chemical parameters on the separation kinetics and improvement of the kinetics model
A. Chiboub*, J. Olivier, J. Vaxelaire, University of Pau and Pays de l'Adour, France
A sewage sludge is the by-product of wastewater treatment, and is mainly composed of water (up to 99% of its total mass), the rest of its mass is the dry solids (DS) (Wu et al. 2020). Prior to the transport and valorisation of these sludges, a liquid-solid separation is necessary. Various processes allow this aim, but their performance is limited and can be enhanced, plus some processes like thermal drying consume high amounts of energy, and needs to be limited (Olivier et al. 2014).
Electro-dewatering (EDW) is a hybrid process in which a conventional filtration-compression process is combined with the application of an electric field in order to enhance sludge dewatering with lower energy consumption compared to a conventional drying process (Mahmoud et al. 2010).
Previous studies (Olivier et al. 2015) have proposed an empirical model that reveals a relationship between the evolution of DS during time (Equation 1), where the dewatering kinetics depends on the properties of the sludge. This model is developed for I-EDW process under a constant electric current, unlike most of the studies presented in the literature where a constant voltage (U-EDW) is commonly used. I-EDW is an interesting operating mode as already mentioned by (Citeau et al. 2012)....
...The objectives of this study are:
Alkaline leaching behavior of zinc from egyptian zinc ore and filtration performance at various pressure difference
D.M. Abdo *, E.A. Abdel-Aal, Central Metallurgical Research and Development Institute (CMRDI), Egypt
This study was performed in two phases of work. In the first stage, alkaline leaching of zinc from Egyptian zinc ore at the Um Gheig area was examined and the influence of the operating variables including stirring speed, leaching temperature, NaOH concentration and liquid to solid ratio was determined experimentally. The optimum condition was found to be NaOH concentration of 4 M, liquid to solid ratio of 20 ml/g, temperature of 80 °C and a stirring speed of 400 rpm for time 2 hrs, in the range of investigated parameters. Under these conditions, the highest recovery of zinc was obtained to be 86.52%. In the second stage, the filtration process was examined under various pressure difference ranging from 0.66 to 0.80 bar. The finding reveals that...
Enhancing egyptian phosphate filtration rate during chemical processing into phosphoric acid
E.A. Abdel-Aal*, Central Metallurgical Research and Development Institute (CMRDI), Egypt
This study was carried out to enhance the filtration rate of phosphoric acid from phosphogypsum during chemical processing of Egyptian phosphate using Dihydrate process. Enhancing the filtration rate was applied using different additives and/or increasing the filter speed. The obtained results are compared with the filtration rates from different international phosphates from Florida, Morocco, Tunisia and others. In industry, better filtration rate of phosphoric acid means higher production as well as less capital and operation costs. Chemical techniques for enhancing the filterability are reaction with the suitable surface–active agent or mixing with a poly acrylamide polymer just before filtration while the physical technique is related to decreasing the cake thickness via increasing rotation speed of filter under the standard applied vacuum. The applied additives include but not limited to surfactants, aluminum bearing materials, oxidizing agents, blending of two phosphate ores, …etc. Phosphoric acid is produced under simulate industrial Dihydrate process. To understand effect of additive from fundamentals point of view, induction time was measured under different supersaturation ratios. The results show that...
Molecular grafting on porous polymer membranes boosts filtration performance
C. Pehoviak*, A. Braun, qCoat GmbH; A. Schulze, Leibniz Institute for Surface Modification, Germany
The production of functional membrane filters is achieved by a one-step surface modification with molecular grafting. Selected functional molecules significantly reduce the tendency of membrane fouling, increase flow rate, save energy, and extend the lifetime of the grafted membrane.
Using low energy electron beams (150-200keV), low molecular weight compounds dissolved in water, are atomically bound on the activated surface of a membrane. The permanently fixed molecules change the chemical and physical properties of the grafted membrane, while the morphology and pore size remain unchanged. Since the electron beam penetrates thoroughly the membrane, the inner surface of the membrane, i.e., its pores, are also activated for the desired modification. Preferably, pore-bound membranes made of PES, PSf, PVDF, PAN, PDMS, PET and PC can be grafted, as flat membrane or hollow fiber /1/.
The choice of functional molecules bound on the membrane depends on the base membrane and the target application. Various economic advantages in operation are derived from primary base effects for the membrane end user, which can be used differently depending on the industry. Field results with the use of grafted membranes in drinking, waste and process water as well as beverage filtration applications, will be presented. ..
Modification of commercial UF membranes by plasma polymerization: Impact on structural / physicochemical properties and filtration performances
S. Déon* , Z. Koubaa, E. Korzhova, P. Fievet, Université de Bourgogne Franche-Comté; A. Airoudj, V. Roucoules, Université de Haute-Alsace, France
Commercial membranes often exhibit difficulties in rejecting multivalent cations, such as heavy metals, due to their usual negative charge. To face this drawback, it is proposed in this study to tailor surface properties of a GK membrane (Osmonics) by allylamine plasma polymerization. The impact of two polymerization durations on both structural/physicochemical properties and filtration performances was investigated. Impact on performances was investigated through permeation flux and ion rejection by cross-flow filtration of single salt solutions as well as ternary and quaternary ion mixtures (containing mono- and divalent anions and cations). Meanwhile, the properties of the modified membranes, namely mean pore radius, roughness, hydrophobicity, and surface zeta potential were estimated to discuss the impact of modification on filtration performances.
It is first proved that modification by cold plasma polymerization is an adequate and sustainable modification technique since...
Thin-film composite polyamide membrane modified by incorporating polyethylene glycol grafted graphene oxide nanoparticles for reverse osmosis
Z. Sanei, A. Sharif *, T. Ghanbari, Tarbiat Modares University, Iran
In recent decades, due to the serious global crisis of water scarcity, reverse osmosis (RO)-based technologies using thin-film composite (TFC) polyamide (PA) membranes, prepared by interfacial polymerization (IP), have received considerable attention. An acceptable membrane for the RO process is characterized by its high water flux and salt rejection. Modifying PA-TFC membranes with nanoparticles has proven effective for improving their characteristics. In this study, the effects of introducing polyethylene glycol grafted graphene oxide (PEG-g-GO) nanoparticles into the thin PA layer were investigated on the structure, morphology, water flux and salt rejection of the final TFC membranes. The impacts of the addition of nanoparticles depended on whether they had been previously dispersed in the aqueous or organic phases of the IP reaction. Thicker and rougher top layers were formed when PEG-g-GO had been added to the organic solution than when they had been dispersed in the aqueous phase of the IP reaction. The results were interpreted in terms of the hydrophilicity of the nanoparticles and their dispersion in the organic and aqueous phases. Furthermore, the TFC membrane prepared by the addition of the nanoparticles to the aqueous phase of the IP reaction showed...
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