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Opening & Plenary Lecture

Day: 08 March 2022
Time: 10:15 - 12:00 h

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


K1 - Keynote Lecture I

Day: 08 March 2022
Time: 13:00 - 14:15 h
Room 1

Session Chair:
Prof. Hermann Nirschl

Simulation of solid-liquid separation processes: Challenges in modeling and experimental validation

Prof. Dr.-Ing. Sergiy Antonyuk / Fabian Krull, 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...


F01 - Filter Media Quality Control / Pore Size Analysis I

Day: 08 March 2022
Time: 13:00 - 14:15 h
Room 4

Session Chair:
Prof. Dietmar Lerche

Intelligent AOI solutions for nonwoven filter media production: simplify your work

T. Dörr*, M. Klein, M. Bradley-Vogel, Dr. Schenk GmbH, Germany

The goal of Automated Optical Inspection (AOI) is to ensure the filter media’s quality and help optimize the production process. Both are achieved by inline inspection of base material and converted material after value-adding roll-to-roll and converting processes or roll-to-sheet process steps. The AOI quality data can be applied to subsequent production steps so only material that satisfies the quality requirements is further processed. The challenge for any nonwoven AOI is the inhomogeneous material structure, generating a lot of “noise” in the signal the AOI cameras receive. This is not an issue as long as the signal-to-noise ratio is good, allowing for detection of defects using a typical single-channel transmission, e.g. a hole in the material. Defects that are embedded in the material though such as a bristle or metal defect, and oil defects are challenging to distinguish from the material background and may escape detection.

This presentation gives an overview of how modern AOI solutions have evolved to make the inspection process quicker, more accurate and easier to control for line operators and product quality engineers.

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...

Filter media and membrane testing by micro- and nano-particles: determination of size and count by a single particle spectrophotometer

E. Wollik, H. Woehlecke, Dr. Lerche KG; D. Lerche*, LUM GmbH, Germany

For the quality and safety of filter media, the retention capacity of particulate components in liquids is often a critical factor. Particle size, size distribution and particle number are important characteristics, whose determination requires valid measuring methods. Number-based quantifying becomes more difficult the smaller the particles to be examined are and creates a great challenge for the measurement technology, especially for particles in the nano- and sub-micrometer range. In this paper, we describe the measuring technique of an advanced photometer measuring simultaneously forward and sideward light scattering of single particles (SPLS-Technology). Light intensities then allow for the determination of size distribution and particle concentration of the nano- and microparticles in suspensions and emulsions with unparalleled resolution and a dynamic range from below 40 nm to 8 µm. We report on the application of this measuring technique for the case of filter media and membrane testing (cut-off). Opto-electronics measures the intensity of light scattered in different directions caused by individual nano- and microparticle as they pass one by one through a very small measuring volume. Separation of particles is achieved by hydrodynamic focusing. A laser (405 nm, non-spherical beam cross-section) illuminates each particle and the scattered intensities are detected by two identical PMT-sensors and two-stage amplifiers with a dynamic range of more than 120 dB. The fluidic system separates particles before they pass the laser focus. The light scattered in the forward and sideward directions is recorded and analyzed in real time, after amplification. The internal sampling rate amounts to 2.5 x 106 s-1 and resolution amounts to 22 bits, respectively. The new sensor system is able to discriminate between very narrow monomodal particle fractions (< 10 nm). The minimum particle number to be detected depends on the particle size (e.g., 1554 nm, 2 particles/ml; 494 nm, 5.600/ml). The table below displays results of filter testing using suspensions of monodisperse polystyrene particles. Mixed samples were filtered through two different 450 nm and a 100 nm filter, respectively. Results show that cellulose filters of the same nominal pore size were more efficient than Nylon ones....


G01 - Surface Filtration

Day: 08 March 2022
Time: 13:00 - 14:15 h
Room 3

Session Chair:
Prof. Wilhelm Höflinger

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 air permeability, mass, and thickness are often utilized to characterize post operational nonwoven filtration media. Nonwoven filtration media commonly displays some degree of variation from the manufacturing process, which can be exacerbated in the used filtration media. Current standard testing methods, laid out in BS 22032:2021, assess filtration media in three localised regions: The vertical top, middle, and bottom of the filtration media. This study shows that there is a considerable permeability variation across the machine and cross direction of the filtration 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...


L01 - Fractionation of Fine Particles in Liquids

Day: 08 March 2022
Time: 13:00 - 14:15 h
Room 5

Session Chair:
Prof. Hermann Nirschl

Continuous fractionation of fine particles using crossflow

P. Lösch, S. Paas*, K. Nikolaus, S. Antonyuk, 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*, M. Gleiß, 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


F02 - Filter Media Quality Control / Pore Size Analysis II

Day: 08 March 2022
Time: 14:45 - 16:00 h
Room 4

Session Chair:
Prof. Dr. Dietmar Lerche

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 [5]. 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...

Characterization of highly interconnected pores by liquid extrusion porometry (LEP), gas liquid displacement porometry (GLDP) and pore network simulation (PNS)

R. Peinador-Dàvila*, IFTS - Institute of Filtration & Techniques of Separation; D. Lasseux, Université de Bordeaux et Arts et Métiers ParisTech; O. Maalal, M. Prat, University Toulouse III - Paul Sabatier, France; J.I. Calvo, University of Valladolid, Spain

Characterization of the pore-size distribution (PSD) of a porous/fibers materials has been widely studied among the scientific community and membrane manufacturers in this terms understanding the constitution, structure and functional behavior of the media have been improved last years with of the media properties and the media process scale up.

The microstructure of a porous medium is generally quite different from a simple bundle of parallel cylindrical tubes. Most porous systems are rather characterized by a system of highly interconnected pores. As a result, the information on the PSD obtained from simple extraction models can be questioned and must be assessed. Another issue is that the PSD so obtained makes no difference between the throats, i.e. the constrictions in the pore space, and the “pores”, defined here as the locally larger cavities

This works aims to study the characterization of several commercial Gas Diffusion Layers (GDL) and FM (Face Mask) by using the experimental techniques Gas Liquid Displacement Porometry (CFP) and Liquid Extrusion Porometry (LEP) for getting their pore size distributions (PSD), mean pore diameters (davg)...

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...


G02 - Respiratory Masks I

Day: 08 March 2022
Time: 14:45 - 16:00 h
Room 3

Session Chair:
Prof. Achim Dittler

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 an existing medical and FFP 2 mask.

The set-up of the CFD model is carried out in 3 stages corresponding to 3 spatial scales. In the first stage, based on µCT scans, individual fibers of mask materials are resolved and filtration efficiency as well as macro-scale material parameters are determined by micro-scale simulation. Stage 2 focusses on the near field of a mask and takes the different mask shapes into account as well as the results of stage 1. 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 three, the exhalation and inhalation 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 is established (Lagrangian approach).

Simulation results of pressure drop and filtration efficiency of medical and FFP2 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 have 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.

Specialized computer simulation tools have proven to be very useful for the innovation and optimization of filtration devices. Previous studies were mostly focusing on filtration efficiency and have not considered the moisture transport. Additionally, the breathing behavior was modeled using an idealized sinusoidal profile or a set of linear functions.

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...


L02 - Filter Presses I

Day: 08 March 2022
Time: 14:45 - 16:00 h
Room 1

Session Chair:
Prof. Gernot Krammer

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, Roxia 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. Using developments and applications in artificial intelligence algorithms in industrial processes, and data from a filtration process consisting of three pressure filters and their auxiliary equipment in a Zinc concentration plant, it will be shown that optimization algorithms subjected to the operative, resource consumption, and quality constraints are viable to provide key operational information...

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, when the filter press will need to be cleaned and the filter cloths will have to be changed.

By using process parameters such as pressure, temperature and feed in combination with the Lenser I-Plate, it’s easy to say 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...



MEMS: How to use them in filter plates to optimize production planning, to increase capacities and continuously to improve product quality

J. Zeller*, JZ Engineering GmbH, Germany

MEMS are Micro-Electro-Mechanical Systems. They are small components that combine logic elements and micromechanical structures in one chip and can process mechanical, electrical and chemical information. MEMS are very small and can be placed at positions which previously could not be reached. The measuring results are less influenced by the measuring devices. The energy requirement for the measurements and transmission of the information is very low. MEMS are able to generate this energy by themselves, they take energy from vibrations, from temperatures or pressure changes.

These properties allow measurements in filter equipment and having the results available during the running process. Further it enables corrections in the manufacturing process which previously were not possible. These corrections are used to protect employees, to improve quality of products, to increase capacities and to protect product equipment and machinery.

The target is, that the filter press learns and initiates appropriate actions, documenting these and informing the user. However, control over the process always remains with the user. For different tasks there are different types of MEMS; combinations of sensors are more and more usual. One of the most common sensor-combination is the accelerometer with gyroscope and the sensor for temperature. This sensor-combination allows monitoring all movements in the filter press. It provides information about position of plates in the filter, that means if plates or equipment is moving or bent due to high forces. It includes also the movement of membranes at membrane plates and allows for example the measuring of cake thickness in chambers in closed filter press. An additional common sensor-combination is used to measure pressures and temperatures in filter presses. These sensors allow...


L03 - Integrated Processes – Crystallization / Separation / Drying

Day: 08 March 2022
Time: 14:45 - 16:00 h
Room 5

Session Chair:
Dr. Nabin Kumar Karna

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

Integrated continuous manufacturing processes of active pharmaceutical ingredients (APIs) and fine chemicals provide key benefits concerning product quality control, scale‑up capability, and a reduced time‑to‑market. Thereby, the crystallization step, which is used in approximately 90 % of API productions, mainly defines the final API properties. Especially, the final product purity is influenced directly by the crystallization step and should be optimized to ensure both consistent purity and particle size distribution (PSD). Upcoming challenges are the solid-liquid separation as well as washing and drying steps to meet specific product specifications regarding residual moisture reduction and preservation of PSD. The overall goal is to create an end-to-end small-scale continuous manufacturing process for the typical API production scale of 250 ‑ 1000 kg per year, starting from raw material treatment to final dosage form. Versatile approaches and concepts are available for small-scale continuous crystallization, divided into the main concepts of mixed-suspension mixed-product removal and tubular crystallizers. Continuous solid-liquid separations, on the other hand, are rather scarce.

In the framework of our research, we patented the Continuous Vacuum Screw Filter (CVSF) for small-scale solid-liquid separation, washing, and drying of particle suspensions. The modular set-up of the CVSF offers a maximized flexibility and thus rapid adaptability to changing market demands and product requirements. This contribution shows the general working principle of the CVSF as well as the results of the systematic apparatus and process characterization...

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...

Quantification of granule formation as a function of solubility in residual solvents

M. Siddique, S. Ottoboni*, C. Price, P. Mulheran, University of Strathclyde, UK; A. Laux, University Toulouse III, France

Pharmaceutical products (APIs) are produced mainly by crystallization to form a high purity product with controlled particle size distribution 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. Traces of residual solvent may also affect the stability of the formulated product. 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. The residual moisture content and composition, solvent polarity, surface tension, and viscosity 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.

The aim of this work was to quantify the correlation between the mass of material deposited during drying and lump formation.....


F03 - Progress in Filter Media Manufacturing

Day: 08 March 2022
Time: 16:45 - 18:00 h
Room 4

Session Chair:
Dr. Harald Anlauf

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.

Ultrafast laser precision drilling of metal and polymer membranes using multibeam scanner and UV-microscanner

M. Osbild*, T. Barthels, M. Reininghaus, Fraunhofer Institute for Laser Technology ILT, Germany

In the field of laser micro and nano structuring, ultrashort pulse (USP) laser processing is attracting increasing attention due to its ability to produce precise hole patterns with highest quality requirements. The multibeam scanner (MBS) enables laser processing with strong parallelization of more than 200 beams for high throughput while maintaining the same drilling quality. The UV-microscanner enables the most precise direct laser drilling of polymers due to its tight focus down to <1 µm and the low heat impact.

The aim is to apply the latest research results and years of process development to new market requirements for laser-drilled membranes such as stainless steel micro filters or perforated polymer membranes in general. The use of USP lasers offers the possibility to produce membranes from stainless steel or polymer films with <1 µm holes. The use of the produced filters is also conceivable for special applications, e.g. as atomizer module in inhalation devices for targeted dosing of antiviral medication or for test device calibration.

Latest USP laser machines like the MBS and the UV-microscanner combine ultrashort pulse laser technology with a sophisticated optical concept. To machine precise filter elements, the primary task is to generate the hole diameter precisely with tolerances of less than 1 µm.

The content of the ongoing research is the drilling of holes with exit diameters of 3 µm and less in stainless steel and various polymers. With the systems presented here, the highest repeatability for the hole diameter can be achieved...

GKD's porometric a test winner once again in performance comparison of nine meshes at exploration company

M. Knefel*, GKD - Gebr. Kufferath AG, Germany

Industrial filtration basically has three main requirements: high flow, low pressure loss and a sufficient particle removal. Of course, these three may not be perfectly reached in one and the same application, but modern engineering methods can help to find an optimum for a given process. This paper intends to show how many years of practical experience and modern simulation methods can be combined to engineer a whole new product. The latest result of this continuous development procedure, the mesh family called Porometric, will serve as an example to illustrate the research process. This ultra-high flow mesh has special pores designed to show a low blocking tendency combined with low in-pore flow velocities to avoid damage when filtering abrasive media. In addition to that the flow rate through the new mesh was tripled compared to other weaving patterns by the use of state of the art CFD simulations. The theoretical and virtual developments were supported by extensive in-house and external performance testing, confirming the expected results...


G03 - Respiratory Masks II

Day: 08 March 2022
Time: 16:45 - 18:00 h
Room 5

Session Chair:
Prof. Paolo Tronville

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, the wearing of certified respiratory masks emerged as a key protective measure against direct and indirect infections from virus-laden aerosols. However, 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 surgical masks (DIN EN 14683 [1]) and filtering face pieces (FFP2, FFP3) (DIN EN 149 [2]).

While the certification of surgical masks and filtering face pieces either uses bacteria- laden aerosol particle distributions with a mean diameter of 3 µm (DIN EN 14683) or liquid paraffin oil droplets and solid-phase sodium chloride particles (DIN EN 149), that neither represent the species nor the size of exhaled droplet nuclei, we use aerosol particles generated from artificial saliva. A comparison of both artificial and actually exhaled aerosol particles shows that...

Filter media testing in accordance with QM and R&D requirements

S. Schütz*, PALAS GmbH, Germany

Air pollution concerning Fine Dust in- and outdoors are currently one of the most discussed topics in public. The new ISO 16890 provides new filter classes ISO ePM1, ISO ePM 2.5 and ISO ePM 10 to forward the operator an idea how far a certain product may reduce the amount of fine dust in his application. As an aerosol either oil (ePM 1), salt (ePM 2.5 & ePM 10) or for very open filter (ePM <50%) dust is used for the fractional efficiency measurement and filter class evaluation. Further dust is used for the dust holding capacity.

Other standards, like ISO 11155-1 or DIN 71466 for cabin air filters, require a fractional efficiency and dust holding capacity test. In the DIN dust and in the ISO salt is used for the fractional efficiency. Both standards use dust for the dust holding capacity. ISO 5011 respectively ISO/TS 19713 for motor engine inlet filters requires dust in very high concentration up to 1.000 mg/m³ for the fractional efficiency as well as for the dust holding capacity measurement.

Usually, the above-mentioned standards are tested at the complete filter element. The efficiency of the complete filter element is resulting from the design of the element as well as the characteristics of the filter material used. The difficulty is now to estimate which filter class results if a certain material is used without manufacturing a completely new element. As the main air flow for such a test is, depending on the size of the sample, up to 120 times lower than for the complete element. This influences especially the requirements for the Aerosol Generators concerning their concentration output. Therefore Palas® has designed a modular filter material test system, the MFP 3000 series, which can perform the whole test procedure according to ISO 16890, as well as parts of cabin air filters or motor engine intake filter at a flat sheet media system.The MFP 3000 series can...

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 community face covering mask.

COVID-19 viruses are from 0.06 to 0.14 microns in size (average of 0.125 microns). Viruses released by infected persons do not float in the air by themselves: they require a medium to travel. COVID-19 viruses attach to water droplets or tiny droplets of aerosols that are generated by breathing, talking, and coughing. These droplets consist of water, mucus protein and other biological materials. Aerosols from human atomization appear to be the dominant route for the transmission of COVID-19. Bioaerosol particles (systems of viable particles such as fungi, bacteria, and viruses suspended in air) are normally larger than 1 micron in size.


G04 - Particle-Collector-Interaction

Day: 08 March 2022
Time: 16:45 - 18:00 h
Room 3

Session Chair:
Dr. Philipp Lösch

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...

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.

As a first step, an ash substitute could be found to load the unit bricks well defined with different masses, different raw gas-concentration and different gas velocities. After the loading process, the unit brick has been analysed using computer tomography (CT). The CT-images provide an insight into each channel to study the particle formation.

To investigate the rearrangement behaviour of already deposited material inside the filter brick, a further module for the wind tunnel was constructed. The task of this design should be to load a filter brick with test material in the first step, in order to be able to overflow it with unladen ambient air in the second step.

The methods and the first results will be presented in this paper...

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...


L04 - Filter Presses II

Day: 08 March 2022
Time: 16:45 - 18:00 h
Room 1

Session Chair:
Prof. Gernot Krammer

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. The cleaning procedures consist of the...


F04 - Filter Media Development I

Day: 09 March 2022
Time: 09:00 - 10:15 h
Room 3

Session Chair:
Dr. Harald Anlauf

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 eco- responsible production of high-quality, specialty fibers. The LENZING™ Lyocell manufacturing process is distinguished by its conversion efficiency and closed loop design, which recovers, purifies and re-uses the process solvent and process water. Fibrillated LENZING™ Lyocell Shortcut fibers may be directly incorporated into filter media formulations.

This work aims to demonstrate the performance enhancement conferred by incorporation of fibrillated LENZING™ Lyocell Shortcut fibers on the filtration performance of a cellulosic base paper formulation. Current and future market trends in Air and Liquid filtration related to sustainability will also be examined...

Pleating characteristics of synthetic filter media: New test method & parameter to assess pleatability using a PLA/PP blend

G. Müller*, F. Bauer, D. Weidt, Sandler AG, Germany

The market for pleatable filters is dominated by media made of glass fibre paper. Such media offer high efficiency and stiffness, which supports a good processability during pleating. However, this material exhibits certain disadvantages such as hygroscopic behaviour or deleterious fibrous airborne matter caused by fibre shedding. Synthetic filter media compensate these drawbacks, which makes them attractive for pleatable filters. However, the media are more difficult to pleat than glass fibre paper, especially on a rotative pleating process. Though, the use of such synthetic media is indispensable due to the various advantages against glass fibre media and the fact that some markets can only be served by rotative pleated media.

As 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, such as polylactide. This work addresses the use of biopolymers from the perspective of processability and pleatability. For this, a meltblown PLA/PP blend was produced on a pilot line and its pleatability on rotative pleating machines was characterised using a new testing method. To the author´s knowledge there is no comparable method and parameter that quantify pleatability of filter media. Therefore, a new testing method is proposed, which involves a new parameter, auxiliary device as well as a small-scale pleating device.

The functionality of the testing method was investigated using media that can be classified as well and poorly pleatable. The proposed parameter pleating angle and the testing method were able to distinguish between those two media classes. The obtained angles of the well and poorly pleatable media are 43° and 97°, respectively.

Finally, the parameter folding angle was used to describe and investigate the pleatability of a PLA/PP blend. The mean of the measurements is 43° and equal to the analysed well pleatable media. Therefore, the measured angles indicate a good pleatability of the tested blend...


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 ...


F05 - Filter Media Development II

Day: 09 March 2022
Time: 09:00 - 10:15 h
Room 4

Session Chair:
Prof. Antti Häkkinen

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. The main task of the filter medium is to retain the impurities, which have to be deposited. 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, 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.

For demanding process conditions, e. g. 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. 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 therefore 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.

An alternative weaving type to produce finest wire meshes are the so called Betamesh-PLUS fabrics. In these plain weave fabrics, the diameters of the warp- and weft-wires as well as the pitches are combined in such a way that these fabrics are characterized by a high permeability, a high dirt holding capacity and ideal back flushing properties. Thus, the Betamesh-PLUS fabrics combine a large number of the advantageous properties in one filter medium. So far, these fabrics could only be woven for pore sizes of approx. 10 µm and coarser. By adapting the weaving technology and the wires used, it has yet been possible to produce this advantageous weaving type for geometric pore sizes down to 5 µm.


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

Y.C. Lau*, 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...


G05 - Industrial Air and Gas Cleaning

Day: 09 March 2022
Time: 09:00 - 10:15 h
Room 5

Session Chair:
Prof. Wilhelm Höflinger

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 (BTU) - Germany

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 media (SMF®) have been pro­duced over the past 15 years, with a peak production of 300.000 m² p. a. The aim is today to use the known advantages of this thin, pleatable SMF® material, such as sharp separation efficiency at 10 µm or good cleanability, for new industrial applications, like hot gas, liquid and process filtration.

SMF® material is a thin (< 0.4 mm) porous sintered metal in which a precisely defined stainless steel powder is sintered and supported by an expanded metal carrier. This re­sults in a mechanically and thermally highly stable filter medium, which can be pleated similar to paper or synthetic filter media. The SMF® base material is industrially man­ufactured as quasi endless sheet that is wound on a coil. Approved for hot gas and exhaust filtration, the material is further processed into typical filter modules for the named applications.

At the beginning the performance of the current filter medium is described by qualify­ing it in line with the corresponding standards of both oil filtration, e. g. multi-pass acc. ISO 16889 and gas filtration in accordance with ISO 16890 and e. g. VDI 3926.

The multi-pass with A4 test dust gives a DHC of 7.18 mg/cm² @ 10 bar and an effi­ciency e.g. Beta 100 of 9.6 µm. Gas filtration tests acc. ISO 16890 are in preparation and results similar to the known media for APC are expected in derivation from other test results from gas filtration with SMF®.

Based on the results of these investigations the standard SMF® material has been adapted via adjustments of the powder metallurgy pro­cess in three steps from 45% to 50% porosity. As a result permeability increases...

Upgrade of existing kiln/raw mill bag filter optimising technology and performances

M. Colombo, M. Rovetta*, 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:

  • premature bags failure, mainly due to overcleaning to manage the very high pressure drop across the filter
  • extremely high compressed air consumptions
  • high power consumptions of the fan

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 and sustainable goals achievable have been...


L05 - Press Filtration – Pressing / Shearing / Electro-Assistance

Day: 09 March 2022
Time: 09:00 - 10:15 h
Room 1

Session Chair:
Dr. Marco Gleiß

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. An innovative method for mechanical dewatering is filter cake compaction by using an oscillatory shear and a low normal pressure. After the successful testing on a laboratory scale, the present work was concerned with the transfer of the compaction process to a continuous filter apparatus. For this purpose, a module for the compaction of compressible filter cakes under oscillatory shear was developed and implemented on an existing indexing vacuum belt filter...

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...


M01 - Waste Water Treatment

Day: 09 March 2022
Time: 09:00 - 10:15 h
Room 2

Session Chair:
Prof. Sébastien Déon

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 polluted with organic and inorganic compounds. If the water 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.

High fluctuating quantities and qualities of this surface water with differing temperature cause high demands on the treatment technology. In biological wastewater treatment processes the retention of activated sludge has to be guaranteed for sudden heavy rain events as well as for longer dry periods. In membrane bioreactors (MBR) biological wastewater treatment is combined with membrane technology for the retention of biomass and particles.

An MBR pilot plant was installed at a waste treatment facility and operated for four months to evaluate the suitability of this technology. The pilot phase proofed that the MBR technology is suitable to treat the polluted surface water in order to fulfil the stipulated discharge limits. The cleaned filtrate can be discharged directly into the receiving water body. The large-scale plant was designed, constructed and put into operation based on the results from the pilot phase. Due to the previously gained experience during the pilot test, the COD limit value was met right from the start of the large-scale plant. Even longer dry periods, a cold winter and sudden hydraulic flushes showed no negative effects on the biological cleaning performance as well as the permeability of the membrane.

A pilot test offers several advantages such as becoming familiar with the wastewater, the operating conditions, but also the important “human factor” in plant management. It is recommended to design the membrane surface with sufficient hydraulic reserves. Thus, a flexibility for higher amounts of surface water can be ensured and the average lower hydraulic load extends the lifetime and generally leads to a relaxed operation mode.

The experiences gained by using an MBR as treatment for surface water at a waste treatment facility show that ...

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...

Old RO membranes end-of-life : from autopsy to reuse as NF/UF/MF or IEM in water and wastewater treatments

M. Pontié*, Angers University; M. Shabani, Tarbiat Modares University, Tehran; S. Awad, IMT Atlantique, France; H. Hannachi, 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, and Israel). We have characterized those membranes in terms of water permeability, salts rejection, roughness changes and physico-chemical characterizations (i.e. ATR-FTIR, wettability, zetâ potential…) by following a membrane autopsy approach. We have by this way develop an original management of those old RO elements as new NF/UF/MF operations and for the first time as a cationic exchange membrane in a microbial fuel cell.

The main aim the present study was to estimate by the way of membrane autopsy methodology the level of performances degradation of end-of-life RO membranes in order to envisage their reuse application as NF, UF, MF or as IEM...


K2 - Keynote Lecture II

Day: 09 March 2022
Time: 10:45 - 12:00 h
Room 1

Session Chair:
Prof. Eberhard Schmidt

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...


F06 - Filter Media Development III

Day: 09 March 2022
Time: 10:45 - 12:00 h
Room 3

Session Chair:
Dr. Lars Spelter

Influence of the layer structure on the filtration performance of fiber fleece-woven wire mesh-composite cloths

M. Müller*, Spörl KG, Germany

Due to their high chemical, thermal and mechanical resistance, metallic filter media can be used in demanding operating conditions. Depending on the combination of the warp wires and the weft wires during the weaving process of woven wire meshes, the production of different types of weave with different aperture sizes and filtration behaviors is possible. With their narrow pore size distribution metal woven wire cloths guarantee an excellent separation and classification accuracy. Depending on the type of weave, the filter media pores can be blocked by separated particles and the pressure loss increases sharply. Pore sizes smaller than 5 µm, especially in the submicron range, cannot be realized with wire cloths.

In the so-called Compomesh composite cloth, wire cloths are combined with metal fiber fleeces on the upstream side. Fiber nonwovens as depth filter media guarantee a large dirt holding capacity and are characterized by a broad pore size distribution. Therefore, also particles in the submicron range can be separated. 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 media the individual filter layers are sintered together.

By combining metal fiber nonwovens with different properties, such as fiber diameter, specific mass per unit area 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 specific requirements of a certain filtration process. Within the paper, the influence of the properties of the individual layers on the overall performance of the composite cloth is investigated in detail. Based on the systematically conducted investigations, it is possible to produce fiber fleece-woven wire mesh-composite cloths, which are explicitly adapted to the specific requirements of a 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, L. Spelter, 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 require 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.

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. However, this does not 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. We develop a simulation chain for the simulation-driven design of new filter media demonstrated exemplary using the spunblown process....

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...


L06 - Filter Cake Washing

Day: 09 March 2022
Time: 10:45 - 12:00 h
Room 5

Session Chair:
Prof. Antti Häkkinen

Tasty wash liquor – Coffee extraction from the perspective of filter cake washing

V. Pannusch*, M. Kuhn, 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...

Impact of cake imperfections during displacement washing processes

F. Sauer*, 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...

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...


M02 - Ultrafiltration

Day: 09 March 2022
Time: 10:45 - 12:00 h
Room 4

Session Chair:
Dr. Thomas Peters

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

I. Duchemin*, O. Lorain, J.M. Espenan, Polymem SA, France

Polymem with its partner Arkema have developed Neophil®, the 4th generation of membrane material. This is a new PVDF material incorporating an innovative amphiphilic di-block copolymer (BCP) 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. Neophil® incorporates an amphiphilic nanostructured dibloc-copolymer in a PVDF Kynar® resin backbone. A deep and permanent anchoring of the BCP into the PVDF matrix thereby offers a long-lasting hydrophilicity. The average pores size of Neophil® is between 15 nm and 20 nm which is normally difficult to achieve in a PVDF membrane. In addition, BCP remains in the PVDF membrane matrix during ageing while conventional additives are almost completely degraded and released out of the membrane. It is showed this type of membrane keeps its pore size distribution constant and its MS2-Phages rejection performances stable, higher than 4log, during all the exposure periods, (Lorain and all 2020).

Several demonstration trials were carried out for tertiary filtration of waste waters. They confirmed the remarkable durability of the performance of Neophil®. Then large-scale plants have been built with this new membrane. Neophil® membranes now equip new tertiary filtration plants where filtered water is used to irrigate grass, corn fields, golf courses… Operating results are presented...

Ceramic membrane technology for efficient separation of chemical degraded lignosulfonates and target products

P. Rinn*, N. Schneider, F. Boruta, M. Ebrahimi, P. Czermak, University of Applied Sciences Mittelhessen; C. Schneider, CMBlu Energy AG, 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...

12:00h - Lunch


K3 - Keynote Lecture III

Day: 09 March 2022
Time: 13:00 - 14:15 h
Room 1

Session Chair:
Dr. Harald Anlauf

Closing the gaps: How can we stop microplastics pollution?

Dr. Katrin Schuhen, Wasser 3.0 gGmbH, Germany

Due to the fact, that microplastics are a global environmental problem, clarity about microplastics pollution, its entry path and distribution, its behavior in ecosystem and influence on human life is important to setting political restrictions and promoting efficient reduction strategies.

During the last two decades, the scientific community started their intensive work in different fields of microplastic research. An overview of the current state of knowledge about microplastics pollution will be given. Additionally, fields of application in which the removal of microplastics from waters is necessary or useful will be presented as well as technological solutions.


F07 - Filter Media Development IV

Day: 09 March 2022
Time: 13:00 - 14:15 h
Room 4

Session Chair:
Dr. Martin Lehmann

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*, O. Lykhachova, Fraunhofer Institute for Industrial Mathematics (ITWM), Germany

Nonwoven filter media are commonly used in multiple filtration applications especially oil and fuel filtrations. The filter media are subjected to the forces from the fluid flow that cause the deformation of fibers and fiber bonds. The flow-induced strong deformation can lead to the irreversible change of the fiber microstructure causing an undesirable change of the permeability and efficiency or, in the critical case, the rupture of the filter medium. For optimization of filter media and filtration processes, the mechanical interactions between the fluid and the filter media have to be described depending on the material properties of fibers and the binder, microstructure and bonding mechanisms by experiments and numerical calculations.

This paper describes the first part of this work that focuses on the experimental characterization of the mechanical properties of relevant liquid filter media. ...

Flow-induced deformation of filter media - part 2: modeling and simulation

R. Kirsch*, 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, 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. This is accomplished by suitable coupling of Computational Fluid Dynamics (CFD) with Computational Structural Mechanics (CSM).

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 and include faster flow regimes (Navier-Stokes-Brinkman). The essential difference between FPSI and the interaction between fluids and solid structures (FSI) is that the forces do not act on the fluid-porous interface (alone), but inside the medium via the pressure gradient, which is a volumetric force density. Therefore, the pressure gradients obtained by the CFD simulations serve as input (volumetric mechanical load) for the CSM computations. The corresponding material parameters are obtained from experiments. The CSM simulation provides – amongst others – the displacement field which is applied to the shape of the filter medium before the flow field for the deformed configuration is recomputed. These two-way coupling steps are repeated until an equilibrium state is reached. Here, two cases are considered: The computational grid is the same for both CFD and structural analysis or they use different grids, which requires additional effort to transfer data between CFD and structural mechanics simulation.

The present paper discusses the algorithmic details such as the verification of the simulation method and the validation by comparison with experimental results....

Filter modeling and simulation with GeoDict

M. Azimian, P. Eichheimer*, A. Weber, A. Wiegmann, Math2Market GmbH, Germany

The recent Covid-19 pandemic showed the necessary demand of filter devices at various scales ranging from face masks to protect human beings from spreading infections as well as providing clean air in interior rooms. For this reason, Math2Market GmbH developed further features in GeoDict software to design, model, simulate and optimize filter media and filter elements at different scales. These features are especially beneficial for many GeoDict users worldwide, which expanded their activities towards digital design of modern and optimized filters.

As shown in Fig. 1, besides design, modeling, simulation and optimization of filter media, single pleat, and filter element, it is now possible to precisely simulate the flow through nano-fibrous media considering slip length on nano fiber surfaces. At the macro-scale, there have been further developed capabilities, especially when simulating the flow through any complicated filter geometry, with or without housing, and also cross-flow filtration simulations e.g., for membranes. Last but not least, solutions for air simulations at room scale considering air purifiers is provided in the GeoDict software...



G06 - Automotive Applications

Day: 09 March 2022
Time: 13:00 - 14:15 h
Room 2

Session Chair:
Dr. Harald Banzhaf

Nanofibered depth filtration media

K. Luukkonen*, A. Fons, Fibertex Nonwovens A/S, Denmark

Nanofiber coated filtration medias have been used for a long time in surface loading filter systems due to easy dust cake release and easy pulsing. In depth filtration applications nanofiber products have not gained notable success. This problem has been related to the premature blinding of the nanofiber layer collecting most of the dust filtered causing a fast pressure drop increase and a short filter life.

On this presentation recent developments to overcome this problem is presented in a form of couple examples on HVAC and cabin air filter applications. As comparative products conventional glass fiber and electret meltblown composite product results are presented.

The development of new combined pleating and dust holding layer overcomes the problems previously associated with nanofibered depth filtration medias. This new type of gradient media acts as an excellent dust holding layer and prefilter to eliminate the premature blinding of nanofiber layer due to excessive dust accumulation. The slow pressure drop increase reduces energy consumption during the lifetime of the filter.

At the same time the media layer functions well in all pleating processes, both in rotary and blade pleating and in further embossing. The new gradient layer can be used in all depth filtration applications from ePM1 >50 % efficiencies up to HEPA grade efficiencies.

CFD simulation of open-cell polyurethane foams using Kelvin model

G.G. Garkhedkar, S.M. Chakote, H. Sauter*, 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)...

Comparative presentation of a filter element test according to EN 15695-2 using monodisperse aerosols classified by aerodynamic diameter

D. Keßlau*, R. Heidenreich, Institute of Air Handling and Refrigeration (ILK), Germany

The objective of the EN 15695 series of standards is to limit the concentration of hazardous substances inside the cabin of agricultural and forestry tractors when applying plant protection and liquid fertilizers. EN 15695-2 applies for filter elements used in tractor cabins of various categories. It also refers to EN 1822-2 and EN 1822-5 concerning a test procedure for determining aerosol separation efficiency of cabin air filters using a monodisperse aerosol. Due to the working principle of the differential mobility analyzer (DMA) used to create that aerosol, test particle concentration is low, and particle size distribution is not absolutely monodisperse.

Research conducted by the ILK Dresden has shown a better solution for this case by using an Aerodynamic Aerosol Classifier (AAC), which in contrast produces a truly monodisperse Aerosol with high concentrations. The separation efficiency...


L07 - Backwashing Filtration

Day: 09 March 2022
Time: 13:00 - 14:15 h
Room 5

Session Chair:
Dr. Marco Gleiß

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 sepa- ration 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 back- washes a planar filter medium with an effective diameter of 100 mm. The process var- iables 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, the cut size of the filter medium is determined before and after a filtration test.

The collected data can be used to sufficiently describe the behavior of filter media during operation as well as the change of its properties due to blinding by particles and mechanical/hydrodynamic stresses...


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...


L08 - Modelling Centrifugal Filtration + Sedimentation

Day: 09 March 2022
Time: 13:00 - 14:15 h
Room 3

Session Chair:
Prof. Ioannis Nicolaou

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 modelling and simulation which, along with the scarcity of computational resources, has resulted in simplified mathematical models that are not adequate for industrial applications. Recently, with the increased availability of computational resources, Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) coupling has become a candidate for modelling 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.

To achieve this, simulations are carried out for two selected aqueous suspensions: calcium carbonate (CaCO3) and microcrystalline cellulose (MCC). LIGGGHTS® (DEM) software is used to carry out the simulations. The particles are...

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...

14.45h - Coffee Break


F08 - Poster Session

Day: 09 March 2022
Time: 14:45 - 16:00 h
Room 4

Session Chair:
Prof. Kyung-Ju Choi

Prevention of microbial contamination and biofilm formation with AGXX®, a new antimicrobial catalyst

M.-L. Harwardt*, M. Hoerteis, Heraeus Deutschland GmbH & Co. KG, C. Meyer, O. Wagner, Largentec GmbH, Germany

Microorganisms such as bacteria and viruses, can be found in abundant numbers in all parts of this planet. While microorganisms are crucial for the basic workings of life, they may also pose a threat to human or animal health. Fighting the spread of harmful microorganisms is one of the main challenges of our time. Ensuring supreme air and water quality by filtration is a crucial contribution to health protection in various fields, such as public transport, car sharing, water treatment, animal farming, or in public buildings. However, global health is endangered by the increasing development of bacterial resistances against antibiotics as well as common antimicrobial technologies.

AGXX is a new antimicrobial technology which is based on a catalytical reaction induced by an interaction of the two precious metals silver and ruthenium. In the presence of water and oxygen, reactive oxygen species (ROS) are generated which target all types of microorganisms by first destroying their outer membranes followed by organelles and DNA. The mechanism is based on a circular redox system meaning that AGXX is not consumed but regenerated continuously. Additionally, the occurrence of a microelectric field between the two precious metals further supports the antimicrobial effect. AGXX is not based on the release of any metals or harmful compounds into the environment and therefore offers long-lasting protection. To this date, AGXX has shown antimicrobial efficacy against over 130 microorganisms including bacteria, viruses, algae, and fungi, among others silver-resistant E. coli s(MRSA), or CoV2 viruses.AGXX has also been shown

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 a steep rise in plastic production and use on the other, 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 through 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 the 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 ...

Filter screen from permeable matrix of pressed metal wire and its properties

A. Shindyalov * 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 introduces 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.

Key advantages:

  1. The elastic system of filter allows:
  • providing multiple regeneration (at least 50 times) with an efficiency of up to 90% recovery of initial properties without dismantling the equipment;
  • change in filtration rating by axial compression, which allows it to be adaptive to changes in filtration fineness requirements;
  • provides durability and high impact resistance of the filtering system;
  • resistance to destruction in a hydrogen sulfide and hydrogen environment (SSK).

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....

Simulation-based optimization and characterization of woven filter screens

D. Herper*, GKD - Gebr. Kufferath AG, Germany

Modern filtration processes have high demands: high efficiency, short and few downtimes and low energy demand. One, if not the crucial part of a filtration device is the filter medium. Developing new filter media solutions is typically time consuming and costly. This is especially true for woven filter screens. Simulation can significantly decrease development timeframes by modelling a new mesh virtually before actually weaving it. In addition to this filtration processes can be simulated and replace long and extensive test runs. In this presentation you will see how simulation on woven media can be carried out in an industrial environment. Various examples will be shown and will illustrate how numerical simulation can generate multiple advantages for filter media manufacturer as well as the client using a filtration process.

Sizable iodine uptake of porous copolymer networks bearing Tröger's base units

S. Shetty, N. Baig, B. Alameddine*, Gulf University for Science and Technology, M. Sherief Moustafa, S. Al-Mousawi, University of Kuwait, Kuwait

Copolymer networks containing Tröger's base units TBP1-3 were synthesized in very good yields from a Sonogashira cross-coupling reaction of a specially designed diethynyl Tröger's base synthon TB with various tetrabrominated aryl derivatives. Thermogravimetric analysis (TGA) of TBP1-3 discloses high 10% weight loss temperature values reaching up to 443 °C. Nitrogen adsorption measurements of the target copolymers TBP1-3 reveal a strong correlation between porosity and the geometry of the aryl spacer whose inflexible rigid structure (biphenyl, TBP1), contorted configuration (spirobifluorene, TBP2), or fused aromatic structure (pyrene, TBP3) affords Brunauer-Emmett-Teller (BET) surface areas ranging from ∼586 m2 g−1 to ∼620 m2 g−1. Inspection of the iodine adsorption properties of TBP1-3 reveals...

Advantages of mobile activated carbon filtration for purification of air emissions

M. Westerkofort*, Desotec, Belgium

Throughout Europe, environmental legislation is becoming more strict. A recent example is the modification of the TA Luft, Germany’s main air pollution legislation, which came into force in December 2021. As a result, there are a lot of companies in various industries who are now facing stricter emission limits or expect their limits to tighten in the coming years. In order to comply to the stricter environmental legislation, additional air purification technology will be needed.
Typical challenges in air purification
In general there are two key challenges that companies in industry face: exceeding the emission limits for VOCs in general or for specific molecules or odour complaints from the neighbourhood. Overall, there are three main sources at companies that lead to emissions. VOCs and odours may be emitted at practically any stage in production processes such as emissions from reactor tanks, coating lines and drying processes. Also in the production halls itself, emissions are possible although concentrations tend to be lower due to diffuse emissions from leaks in valves or sealants. The last main source is the storage of chemicals, both on a small scale such as the storage of a specific solvent for paint manufacturing as on large scale such as the storage of petrochemicals in ports.
Application area of different technologies
As the challenges in air purification are very diverse, many different technologies exist to purify air emissions. The application areas are illustrated in Image 1. Activated carbon is typically used in the lower concentration ranges. On the other hand, activated carbon is a good technology in a wide range of flowrates. Additionally, it is often used for discontinuous operations. Unlike thermal oxidisers or biofilters, no natural gas has to be burnt and no strict process conditions have to be managed for the microorganisms when there is no production. Although activated carbon is not always economically viable on the long term for very high VOC concentrations, it is still used in these applications. However, this is often for temporary use during maintenance or unexpected shutdowns and in emergencies...


G07 - Poster Session I

Day: 09 March 2022
Time: 14:45 - 16:00 h
Room 5

Session Chair:
Prof. Gerd Mauschitz

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, C.R. de Lacerda*, 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...

Synergistic effect between electrostatic precipitation and fabric filtration of nanoparticles

B.J. Chiaramonte 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...

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...

ISO ePM1 60 % grade type filter (F7) behavior in a building with air recirculation

V. Silvonen*, L. Salo, T. Raunima, P. Karjalainen, J. Vinha, T. Rönkkö, Tampere University; I. Kulmala, VTT Technical Research Centre of Finland Ltd, Finland

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 (the portion of recirculated exhaust air of the total supply air) was measured as 0.65. The single-pass efficiency of the filter is compared to the apparent particle penetration when air is recirculated, showing a benefit of air recirculation...

Nanofiber filtration for gas turbines

C. Akduman, Pamukkale University, V. Demirel, F. Tezcan*, Hifyber - Acik Kart Bilgi Teknolojileri , Turkey

High efficiency air filtration is a basic requirement for the most cost-effective operation of high efficiency gas turbines. According to the region and environment, ambient air includes high amount of dust, hydrocarbons, water and salts. The quality of the air entering the turbine through the filter material is a significant factor in the performance and lifetime of the gas turbine [1]. The filtration system protects the gas turbine from damaging debris. Also, as the dust load increases, the pressure drop across the filter increases and gas turbine performance and power output are negatively affected [2]. In gas turbine/dust collector applications, the higher filtration efficiency and lower pressure drop can be achieved with nanofiber coating which provides higher equipment protection and lower energy consumption than traditional media and also meant reduced soot fouling and maintenance requirement. With a nanofiber performance filter layer, the dust accumulates on the surface of the filtration media rather than within the media and could be cleaned off easily with a back pulse resulting in long filter life and a low operating pressure drop.

Nanofibers are produced in the form of spider web like structures [3]. Because of easy usage and ability to fabricate nanofibers, electrospinning is one of the most commonly used method [4]. Nanofiber media have low weight, high air permeability and small pore size that make them suitable for various filtration applications, particularly for smaller particles [5-7]. The nanofiber layer collects dust, dirt and contaminants on the surface of the filter; and this layer increases the filtration efficiency of cellulose, cellulose/synthetic or fully synthetic conventional filtration media. In a nanofiber based cleanable media, the nanofiber layer is the upstream side and dust accumulates on the surface of the filtration media rather than inside the media and can be easily cleaned off with a back pulse, resulting in long filter life and low operating pressure drop.

When nanofiber coating on corrugated cellulose/synthetic filter media adjusted for five filtration efficiency level as 50 ≤ E < 60, 60 ≤ E < 70, 70 ≤ E < 85, 85 ≤ E < 95 and 95 ≤ E, it was seen that...

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 [1]. 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...


G08 - Poster Session II

Day: 09 March 2022
Time: 14:45 - 16:00 h
Room 3

Session Chair:
Prof. Gernot Krammer

Conceptional design for 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....

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. A new approach is to circumvent the energetic disadvantage by combining the processes in one process step. 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.

The new process for reducing the heavy metal load of sewage sludge and using it as fertiliser was presented and various filter materials for this purpose were investigated. Important parameters were...

Improvement of dust release functions on the basis of single particle investigations

N. Woschny*, 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 hazards for the environment and humans, prediction methods determining the dust mass reliable during a process step have to be developed.

In order to improve the dust release functions investigated in a previous project collaboration between the Institute of Particle Technology (University of Wuppertal) and the Chair of Mechanical Process Engineering and Solids Processing (Technische Universität Berlin) [1] 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 Reference 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. Then, these data are implemented in the existing dust release functions improving their accuracy...


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...


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 materials takes place in the building materials industry, agriculture and the food industry, among others. Bulk material handling, transport and storage result in the particle emissions, 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 emissions. 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 using different operating parameters for dust emission as well as separation. The subsequent electrostatic charging of the spray mist allows the use of water and compressed air to be reduced. An evaluation method for spray nozzle systems is being developed, which considers the economics of the used resources and the material-related efficiency of the reduction...


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 ...

Flow field andperformance comparison of single and double inlet cyclone separators with different inlet types

Z. Wang*, G. Sun, China University of Petroleum . China

Cyclone separators, as a gas-solid separation device, are used in various fields. It is a common method for performance improvement of cyclone separators to use a symmetrical double inlet structure [1-4]. However, in the existing conclusions, it is found that symmetrical double inlet structure can both increase the pressure drop [1] and reduce pressure drop [2-4], which is confusing and has not yet been explained, which may lead to the case that the double inlet structure cannot be conducive to optimizing the performance of the cyclone separator in practice.

Through literature review, the conclusion of performance comparison between single and double inlet cyclone separators may be affected by selected types of inlets, such as tangential inlet [2-4], volute inlet [1]. As a result, it is essential to investigate the influence of the inlet type on the flow field and performance of the double inlet cyclone separator.

In this paper, two kinds of a common single inlet and four kinds of double inlet geometry with the same inlet area were proposed and the efficiency, and pressure drop were mainly studied by computational fluid dynamic (CFD) method....

Application of high-speed camera to measuring particle velocity distribution in a cyclone separator

M. Cao*, J. Che, X. Fan, Y. Hao, H. Cui, China University of Petroleum, China

This study focuses on analyzing the particle velocity characteristics in a cyclone separator to reveal the mechanism of the separation space. The test cyclone separator was made of plexiglass with an inside diameter of 160mm. The glass particle of density 2453kg/m3 with diameters of 150μm was used as conveying materials. This study applied a high-speed camera (FASTCAM SA-X2) to measure particles' velocity and inclination angle in a cyclone separator. We set four observation points along the circumferential direction. The calibration of the high-speed camera suggests the method was capable of measuring particle movement with errors of no more than 3% , and the high-speed camera was proven to be a helpful method in gas-solid flow study. This experiment measured the particle velocity distribution at an inlet air velocity of 20m/s and the solid concentration of 100g/m3~1700g/m3. The results suggest...


L09 - Poster Session

Day: 09 March 2022
Time: 14:45 - 16:00 h
Room 1

Session Chair:
Dr. Nabin Kumar Karna

Magnetic seeded filtrations 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...

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...

Mechanisms of bacteria transport and filtration in porous media for soil remediation purposes

X. Zheng, Y. Rossez, E. Lamy*, Sorbonne Université, Université de Technologie de Compiègne, Frnce; H. Bai, Henan University of Technology, China

Bioremediation technologies such as bio-augmentation, bio-stimulation or natural attenuation have widely been proposed as cost-effective means for soil treatment of contaminated sites. These techniques rely on the use of bacteria to degrade or immobilize recalcitrant pollutants. Although bioremediation has many advantages compared to the traditional technologies, it is important to recognize that some scientific challenges need to be met, due in part to our lack of understanding of microorganism interactions in different hydrologic environments. The design of efficient bioremediation strategies can be improved by a better understanding of the complex interplay of physical, chemical, and biological factors affecting bacteria transport and filtration. Differences in transport and filtration behavior can be caused by bacteria surface properties that will influence interactions with the surfaces of solid soil particles. Bacteria transport and filtration is more complex in the vadoze zone, when compared to that occurring in the saturated zone, due to the presence of air phase in the pores. Bacteria may interact with these multiples interfaces (air-water-solid) and this may highly influence the mechanisms of filtration as well as the amount of bacteria retained. The objective of this work was to investigate bacteria filtration mechanisms under saturated and unsaturated flow conditions....

Hydrocyclone for reduction of abrasive wear in sand trap piping of wastewater treatment plants

T. Senfter, S. Kahl*, 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...

Study on performance of parallel common bucket of hydrocyclone

X. Liu*, J.-Y. Chen, H. Cui, Y. Zhou, M. Cao, X. Ma, China University of Petroleum, China

Hydrocyclone separator is a device that uses centrifugal force to separate multiphase substances with different densities. It is widely used in wastewater treatment, oil-water separation and other fields. While the development of hydrocyclone, the separation efficiency and treatment capacity become the factors limiting the application of this technology. On the one hand, the high treatment capacity requires the hydrocyclones with large diameter, on the other hand, the separation efficiency of hydrocyclone will decrease with the increase of diameter. The parallel connection of hydrocyclones is a solution to increase the treatment capacity. However, compared with the single hydrocyclone, the separation efficiency of parallel hydrocyclones will decrease.

A new type of common bucket is designed to solve the problem of the decline of separation efficiency of parallel hydrocyclones, which can make the parallel rotating flow field produce inherent stability, and reduce the negative influence of the air core on the separation performance through the self liquid sealing. In this paper, the influence of the common bucket on the stability of parallel flow field in liquid bucket and the separation performance is studied by numerical simulation...

Filter cake washing: Unintended cake reslurrying as a wash limit

F. Sauer, 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*, H. Henn, B. Hoffner, Mannheim University of Applied Sciences, 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...


On pore scale numerical simulation of complex homogeneous reactions with application to filtration processes

O. Iliev, P. Toktaliev*, Fraunhofer Institute for Industrial Mathematics (ITWM), Germany

Numerical modeling at pore-scale which is based on high-resolution CT images has proven its validity and importance in many areas. It is especially important in the case of heterogeneous porous media (e.g., broad pore size distribution with potential for channeling effects) and chemical heterogeneity (e.g., nonuniform distribution of the size and locations of the washcoat particles/coating layer in the case of catalytic filters, nonuniform distribution of the size and locations of active carbon particles in air filters, etc.). Typically the reactive transport is described by convection and diffusion processes in the pore space and by homogeneous reactions within the reactive particles (washcoat, active carbon, etc.). Note that earlier we have addresses heterogeneous reactions, here we concentrate on homogeneous reactions, mainly in connection with catalytic filters. To be more precise, the reactions are heterogeneous at nanoscale, however here our investigations are carried out at micron scale, and the nanoscale heterogeneous reactions are averaged to homogeneous reactions at micron scale. To tackle pore scale simulation of reactive transport Fraunhofer ITWM has developed PoreChem Software which is a highly scalable solver for multispecies reactive flow in porous media. PoreChem uses a voxelized representation of geometry, includes implementation of numerical solution of Stokes(-Brinkman) equation for the flow problem and convection-diffusion-reaction equations for species transport, and can be used for problems with up to tens of billions of voxels.

In [1] PoreChem was used for pore scale simulations in the case of first order reaction. The role of the geometrical and chemical heterogeneity was highlighted. Nevertheless, reduction of the whole Selective Catalytic Reduction (SCR) process to a first order reaction has limited applicability and neglects reactions in the non-porous region and complex chemical transformations in the washcoat. Thus, in the current paper, we discuss several complex reactions...

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.

The study focuses on the first part of the process (sludge module), evaluating the solid-liquid separation performance by means of a filter press, without the use of polyelectrolytes or other filtration conditioning, depending on the operating conditions of the hydrothermal carbonization reactor, in particular temperature, pressure and residence time.The results show...


JZ-analysis-system for membrane filter presses and filter towers to increase capacity and to improve quality

J. Zeller*, JZ Engineering GmbH, Germany

In the field of solid-liquid separation, membrane filter plates have been established in filter presses. Using membrane filter plates, a higher solid content of sludges can be achieved in less time compared to chamber filter plates. In membrane filter presses capacity and quality of cake and filtrate depend on a lot of factors and in particular on condition of filter cloth and membranes.

With the developed JZ-Analysis-System, information in the filter plate pack, a so-called Black Box, are made transparent. Now collected data refer to leaking membranes, blinded or damaged filter cloth, cake thickness distribution in different chambers and filling degree of the complete filter. This information is transmitted wirelessly from the plate pack to smartphones, to laptops or is sent to the control centre. All these data are available during the running process, during squeezing the membrane plates, and allow a fast reaction already during the process.

If squeeze medium is lost, the Analysis-System will indicate the number of the affected membrane plate and the operator is able to change this plate during the next cake discharge. No additional searching for the plate is necessary. If filter cloths are blinded, broken or not fixed properly, the Analysis System will indicate the corresponding chambers again during the running filtration process and the filter cloths can be corrected during cake discharge. After the squeezing step our Analysis-System will indicate, if the complete filter is overfilled or underfilled. This will influence the results of...

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...

Development of an innovative arduino-based multi-sensor for the online-monitoring of growth and health parameters in smart aquacultures

F. Boruta*, P. Rinn, O. Schmitz, M. Ebrahimi, University of Applied Sciences Mittelhessen; T. Wilke, 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


F09 - Surface Finishing of Filter Media

Day: 09 March 2022
Time: 16:45 - 18:00 h
Room 4

Session Chair:
Prof. Kyung-Ju Choi

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, oleophobic or dielectric. 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, nanofibers or film a clear competitive edge.

The paper 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 dielectric nanocoatings (Nanofics®K or ‘Kappa’) 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 paper 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 widely rely on PFAS, deposited through wet coating or padding process. However, PFAS are restricted under REACH and, in case of C8 chemistry banned of 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) and allows functional coating without damaging the web. Chemistry is injected in vicinity of the plasma area (Figure 1), inducing the plasma polymerization of surface finishes. Here, water and oil repellent coatings on PE fabrics are shown. Then, we discuss on how plasma parameters and precursors modify the coating performances such as wettability, adhesion and so on. Finally, we present few examples of coating such as halogen-free water repellent finish...

Lotus range™ filter media

T. Soyer, Clear Edge Germany GmbH, Germany; D. Fogg*, Clear Edge, 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...


G09 - Filter Test Systems

Day: 09 March 2022
Time: 16:45 - 18:00 h
Room 3

Session Chair:
Prof. Achim Dittler

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...

Penetration test of face masks –standards, 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....

Palas® has developed with the PMFT Series a new test bench which covers the requirements of all standards and will give therefore comparable test results. The PMFT Test system is equipped with two Aerosol Generators for oil and for salt and includes for Aerosol Mass and Size detection the well-known Promo® Aerosol Photometer with a size range from 100 nm up to 40 µm.

In this paper we will show the influence of differences and tolerances concerning the test conditions, especially the mass concentration and size distribution of the Aerosol to the test results of face masks. The second focus will be the reflection of the influence of the measurement device used for the test and how the instruments can be adjusted to get comparable results about all standards.

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:

  • Two types of test aerosol, NaCl and Emery Oil
  • Different types of flat-sheet media
  • Different flow rates

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...


L10 - Modelling Pressure Cake Filtration

Day: 09 March 2022
Time: 16:45 - 18:00 h
Room 1

Session Chair:
Dr. Pascal Ginisty

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

T. Buchwald*, U.A. Peuker, Technical University Bergakademie Freiberg, Germany

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/VfVf–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 several wash cycles in order to deliquor 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...


L11 - Depth Filtration – Adsorption

Day: 09 March 2022
Time: 16:45 - 18:00 h
Room 5

Session Chair:
Dr. Lars Spelter

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...

Engineered carbon based filtration for the removal of micropollutants and microplastics from municipal wastewater treatment plant effluent

C. Perego*, R. König, P. Principi, University of Applied Sciences and Arts of Southern Switzerland (SUPSI); M. Süsser, DrM Dr. Müller AG, Switzerland

The optimization of industrial, civil and agricultural processes for higher resource efficiency, separation of rain and black water and the increasing awareness of water value lead to a decreasing wastewater discharge resulting in higher concentrated wastewaters.

Emerging contaminants, MicroPollutants (MPs) and MicroPlastics (MPlas), have become important for municipal and industrial wastewater treatment, as surface water high quality is the fundament of drinking water quality.

Industrial chemicals and Active Pharmaceutical Ingredients (API) lead to increase heterogeneous organic chemical loads, which are often poorly degraded in conventional municipal wastewater treatment plants (WWTP).

First mover plants are tackling this issue with quaternary treatment steps, using ozonization or carbon-based sorption processes to remove MPs and to retain plastic fragments. The processes are anyway still subject to optimization due to incomplete oxidation products, Powdered Activated Carbon (PAC) loss and sustainability.

This project develops a technological innovative solution, revamping an existing industrial candle filtration product, towards a tailored solution for MPs adsorption through PAC and MPlas retention, within a unique process combination.

The innovative filtration process combines an engineered mixture of PAC and a filter aid (cellulose) with pre-coat filtration. The main challenges are hydraulic performance, resources optimization and MPs and MPlas elimination performance. Testing several carbon/filter aid combinations in laboratory scale, allows insights in the MPs and MPlas removal performance. To evaluate the optimization of hydraulic performance and of resource conservative PAC/filter aid mixture, experimental design is used during test set-up and results’ statistical evaluation. Best operation settings are characterized by...


M03 - Ultra- and Nanofiltration

Day: 09 March 2022
Time: 16:45 - 18:00 h
Room 2

Session Chair:
Prof. Pierre-Yves Pontalier

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, Surflay Nanotec GmbH; M. Krug, C. Staaks, inge GmbH - DuPont 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

The remediation of waters containing ionic pollutants such as heavy metals is an overriding issue for many types of industries and membrane technologies, and especially nanofiltration (NF), are a relevant option. NF allows a good removal of ionic compounds due to mechanisms governed by both size and electrical charge. For decades, many researchers have developed models to predict the filtration performances of nanofiltration. Such models can be useful for the development of new processes, the diagnostic, scale-up or optimization of existing processes. In literature, several approaches are proposed based on phenomenological permeances or mechanistic description of mass transfer. Among all the models available, those based on the coupling between transport within the membrane pores by convection, diffusion and electro- migration, and an equilibrium partitioning at the membrane/solution interfaces, governed by steric, electric and dielectric exclusions, have shown the best potential. These models have demonstrated their ability to describe the rejection performances for salts solutions and multi- component ionic mixtures. Nevertheless, simulations are always carried out in full recycling mode, which means by recycling both retentate and permeate streams into the feed tank.

In works published, 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.

Two different tubular ceramic membranes were investigated for this concept, a NF membrane (IKTS Fraunhofer, Germany) with 200 Da MWCO and a UF membrane (Atech, Germany) with 10 kDa MWCO. All experiments were ...


G10 - Modelling and Simulation I

Day: 10 March 2022
Time: 09:00 - 10:15 h
Room 5

Session Chair:
Dr. Martin Lehmann

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*, M. Azimian, 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 [1]. 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. [2] 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 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...

Performance of a sampling cyclone at different flow regimes

D. Misiulia,*, S. Antonyuk, 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)...


G11 - Air Filtration I

Day: 10 March 2022
Time: 09:00 - 10:15 h
Room 3

Session Chair:
Matthias Waldenmaier

Electret filter media: Experimental and numerical study of submicron aerosol deposition

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 fine particles from gases. In addition to the mechanical deposition mechanisms, particles are deposited by electrostatic effects as the fibers are electrostatically charged. However, the particle deposition is reduced within operation, since already deposited particles alter the fiber charge and thus weaken the above-mentioned electrostatic effects. Standards mimic this ageing by discharging with isopropanol (IPA).

In this work discharged electret filter media were experimentally investigated applying different discharging methods (liquid IPA vs. IPA vapor), while the media are exposed to a sodium-chloride test aerosol with a bipolar equilibrium charge distribution. The test aerosol is therefore conducted through an aerosol neutralizer. The particle size distribution is measured upstream and downstream the electret filter media with a Scanning Mobility Particle Sizer obtaining the filtration efficiency. It could be shown that...

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...

The new approach to evaluating air filters under the ErP directive

T. Stoffel*, DELBAG GmbH, Germany

The Ecodesign directive was first passed by European legislative bodies back in 2009. It created an at the time unprecedented legal framework for attaining the climate goals within the realm of energy-consuming products. This meant that the manufacturers across the board were obliged to increase the energy efficiencies of their products. Naturally, this directive has since its initial enforcement affected mechanical engineering as well as the manufacturers of decentralized and central ventilation systems. Electric motors drive the fans in ventilation systems and are therefore not exempt from the legislative bill. And yet once again, the requirements for reducing energy consumption in commerce were once again tightened in July 2021.

Until then, calculating the SFP energy consuming contribution caused by the air filters under the ErP directive was based solely on their initial pressure drop across all the filters in the air treatment system. This approach to calculating the air filters contribution to a CO2 footprint has been subjected to professional scrutiny for a long time.

Despite the introduction of an energy classification scheme for air air filters 10 years ago, evaluating the SFP value under the ErP Directive regarding the filters failed to change under the Ecodesign Directive during this time.

The new version of the ErP directive that came into force in mid-2021, however. has been welcomed by experts for its re-evaluation of air filters. The new version of the directive no longer assesses an air filter for its initial pressure loss only. The new version is based on ...


L12 - Modelling Decanter Centrifuges

Day: 10 March 2022
Time: 09:00 - 10:15 h
Room 1

Session Chair:
Prof. Urs A. Peuker

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), 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...



M04 - Modelling and Simulation

Day: 10 March 2022
Time: 09:00 - 10:15 h
Room 4

Session Chair:
Dr. Thomas Peters

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

Porous Membranes are widely used in water treatment. When the membrane filtration process is operated in dead-end mode, the driving force is generated by applying certain pressure to the feed side that forces the water to flow through the porous membrane to the permeate side. For simulation the membrane is usually considered as a single permeable body with unified permeability. In fact, however, the active part of the membrane is a surface with a discrete distribution of pores of different sizes. Such a system has a high complexity because the fluid will penetrate the membrane depending on local permeabilities inhomogeneous. This will result in a boundary layer close to the membrane surface in which a distribution of tangential streamlines is found. It is suspected that this will impact the formation of particulate fouling. This highlights the demand to develop a generic model able to consider the membrane-related aspects in addition to defining reliable boundary conditions that fits with the problem and predicts the corresponding axial and radial velocity profile. Computational Fluid Dynamics (CFD) is an interesting alternative for modelling and simulating membrane filtration systems, even though complex geometries can be however quite challenging in terms of computational cost and calculations efforts. In this regard, a code package using SIMPLE algorithm with appropriate boundary conditions and parameters related to porous membranes has been used for simulations. The focus of this work is the simulation of a small rectangular area of a membrane surface in a dead-end operation...

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 future biorefineries. However, membrane fouling is inevitable in membrane operations, and several fouling aspects are still poorly understood. 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 employed fluid dynamic gauging (FDG), an in situ, real-time monitoring technique, to estimate the thickness and strength of the fouling layers formed.

In this work, the fouling behavior of microcrystalline cellulose (MCC) during cross-flow microfiltration (MF) was investigated at 40 kPa transmembrane pressure using 0.45 µm polyethersulfone (PES) membranes in a series of membrane flushing and physical cleaning....

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 [1] 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...


M05 - New Processes

Day: 10 March 2022
Time: 09:00 - 10:15 h
Room 2

Session Chair:
Prof. Pierre-Yves Pontalier

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...

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...

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...

10:15h - Coffee Break


G12 - Modelling and Simulation II

Day: 10 March 2022
Time: 10:45 - 12:00 h
Room 3

Session Chair:
Dr. Martin Lehmann

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:

  • The flow passes through a plugged or un-plugged monolith
  • The molecules interact with the washcoat layer and the catalytic centers within
  • The catalytic reaction is simulated in the micro scale

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.

The size of the bag filtration plant with its high number of filters to be considered, the complex dynamic interactions between the continuous particle deposition on filters, the local increase in flow resistance at the filter and the associated flow and deposition relocation 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 flow shift into account, adapted calculation tools are required especially for these problems.

In the case study presented here, the CFD modelling was done using the filter modelling tool from DHCAE Tools based on the CFD toolbox OpenFOAM. The modelling extension uses an Eulerian-Lagrangian approach whereby the interactions between filter loading, shift of the continuous flow due to the increase in resistance and subsequent particle deposition are considered in an iterative process.

The meshing of the geometry is of particular importance in the implementation of the simulation model: to be able to resolve the large number of bag filters in the iterative loading process, a particularly efficient meshing technique is required to ensure high mesh quality with lowest number of elements possible. This was achieved by...


G13 - Air Filtration II

Day: 10 March 2022
Time: 10:45 - 12:00 h
Room 4

Session Chair:
Matthias Waldenmaier

Test methods for indoor air cleaners in the context of COVID-19

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 growth has significantly increased during the COVID-19 pandemic as air cleaners can 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. However, the CADR is usually given only as a size-integrated value for particles >0.3 μm. Correspondingly, it does not take into account ultrafine particles, which include individual airborne viruses, nor does it allow conclusions to be drawn about the size dependency of the collection efficiency in the range of exhaled droplets.

Thus, a test method was developed which determines the CADR as a function of the particle diameter the size range of exhaled droplets as well as for the average size of the SARS-CoV-2. Potassium chloride (KCl) particles were used as a surrogate for individual SARS-CoV-2 by classifying the fraction at 0.12 µm from a polydisperse aerosol using a differential mobility analyzer (DMA) and counting the particles with a condensation particle counter (CPC). The exhaled droplets were simulated by paraffin, covering well the range between about 0.1 and 1 µm. The droplets were measured with an optical particle counter (OPC) and an aerodynamic particle sizer (APS) to cover a broad size range.

We show for different air cleaners with fibrous filters that they are capable to subtantially reduce the concentration of particles in the size range of viruses and virus-laden droplets. By comparing filters with different efficiency in the same air cleaner we demonstrate that...

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. Marval, M. Rubio, P. Tronville, Politecnico di Torino, Italy

The concentration of airborne particulate pollution and its mass distribution, as a function of the size of the particles captured during the air filter's service life, strongly affect how their airflow resistance changes throughout its 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 challenging because of the high concentration of atmospheric sub-micrometer particles that clog fibrous filter media quickly. 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.

These considerations are relevant and of practical interest for most air filters, especially those used in gas turbine air intake systems. 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 natural ageing processes as closely as possible is highly desirable. This procedure would allow to design and optimize the filter media and the filter cartridge geometry, together with 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 in the laboratory in a few hours. The mass distribution as a function of the particle size of such aerosol should be as close as possible to one of the typical urban atmospheric aerosols. The intent was to reproduce the same loading kinetics governing the ageing process in standard air filtration systems serving gas turbine applications.

According to the currently standardized procedures, several types of air filters manufactured with different filter media were loaded in the laboratory by dispersion of ISO A2 Fine and Kronos titanium dioxide synthetic dusts, according to the currently standardized procedures (ISO 16890-3:2016). The same filters were also aged with a KCl ultrafine aerosol in the laboratory. This aerosol was generated with a new procedure employing a thermal aerosol generator burning a salt stick. This new procedure provides a particle size distribution much closer to the typical urban aerosol, like in ISO 16890-2:2016. The test dust capacity obtained with ISO A2 Fine dust is around four times higher than that obtained with Kronos 2160 dust ...


L13 - Flotation-Adsorption-Coalescence / Surface Effects

Day: 10 March 2022
Time: 10:45 - 12:00 h
Room 1

Session Chair:
Dr. Katrin Schuhen

Novel method for removal of microplastics from various waters using organosilanes

M. Sturm, D. Schober, A. Korzin, Wasser 3.0 gGmbH / abcr GmbH; S. Haubensack, 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, based on Green Chemistry, 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 them, form agglomerates and fix them chemically. The trick is that MP agglomerates then float onto 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 removal processes - and to generally identify microplastics hotspots and sources in the global watercycle -, microplastics in the water need to be quantified. However, microplastics´ monitoring in waters with conventional 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. In the sense of a future circular economy, we also investigate ways to reuse and recycle the microplastics agglomerates from the treated 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 the detection, removal, and reuse of microplastics from wastewater, industrial process water, seawater, and freshwater systems. It achieves environmental protection, sustainability, and resource efficiency with low-tech, low-maintenance and low-cost solutions...


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

Modern water-diesel separators employ a so-called two-stage approach, which combines both hydrophilic and hydrophobic materials to collect and separate the suspension of water. The hydrophobic layer (sieve) is designed to have a low wettability such that the collected mass retains almost spherical and falls along the sieve due to gravity. In general, the droplets exhibit complicated and various interactions with the sieve: partial clogging, retention (breakthrough), and drainage (rolling or sliding). In addition, those interactions interfere with the flow fields yielding an additional pressure drop, which in turn affect the dynamics. On the other hand, the choice of the material of the sieve affects its efficiency and the overall pressure drop. The sieves are characterized by the wettability condition, open-area ratio, and the mean fiber diameter. Thus, studying the effect of the properties of the sieves on the dynamics of a single droplet is vital to quantify the mechanisms in the process of liquid-liquid separation.

The present work uses the computational fluid dynamics (CFD) package OpenFOAM®*, coupled with an improved scheme designed for an accurate computation of the surface tension force for capillary dominated regimes in the framework of the volume of fluid (VoF) method. Fully resolving simulations are carried out to simulate the interaction of water droplets in a diesel fuel flow with a screen mesh. This study yields correlations, which...


L14 - Metrological Analysis of Data for Particle/Liquid-Separation

Day: 10 March 2022
Time: 10:45 - 12:00 h
Room 5

Session Chair:
Prof. Dr. Dietmar Lerche

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

Monitoring of product compositions is essential for the control of unit processes. Nowadays, it is given a clear preference to in-line solutions. Product quality parameters have to be observed in almost real-time and the sensor should be used for different applications. This contribution introduces the Multi-Reflectance-Spectroscopy (MRS) as an innovative technique based on multiwavelength reflectometry for in-situ quality/process control of suspensions and emulsions. This technology is fast, has no direct contact to the sample and is applicable without any chemicals and sampling.

Using machine learning approaches, the measuring signals can be correlated with quality parameters of dispersions (e.g., suspended solid concentration or particle size) with high accuracy. We present exemplary the potential of machine learning methods improving prediction-accuracy in process industry and give various example applications and results of suspensions and emulsions...

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...


M06 - Water Production

Day: 10 March 2022
Time: 10:45 - 12:00 h
Room 2

Session Chair:
Prof. Sébastien Déon

Membrane distillation for the production of pharmaceutical-grade water

C. Nellessen*, T. Klein, EnviroFALK PharmaWaterSystems GmbH; H.-J. Rapp, DEUKUM GmbH; F. Rögener, Technical University Cologne, Germany

Water is the most important medium in the pharmaceutical industry. The production of ingredients, intermediates and final products heavily relies on water. The required water quality depends on the intended purpose and this in turn influences the effort involved in water treatment. Water for pharmaceutical purposes is strictly regulated. Both quality and treatment processes must comply with legal guidelines. In the European Union the European Pharmacopeia (Ph. Eur.) sets the standards for the quality of medical products. The Ph. Eur. differentiates between Water for Injection (WFI) and Purified Water (PW).

Today the production of water for the pharmaceutical industry is mainly based on distillation (thermocompression and multistage distillation) and membrane processes, especially the combination of reverse osmosis, electro chemical deionization and ultrafiltration. Both processes are highly complex multistage processes which in case of distillation also have high energy demands.

Membrane distillation (MD) as a relatively new method is an alternative for pure and ultrapure water production. A thermic process used for the separation of two liquids with different temperatures from each other. Heated-up feedwater (50-80 °C) is separated from the cooled distillate by a hydrophobic, porous membrane. The driving force for the transmembrane mass transfer is the vapour pressure difference induced by the temperature difference. Because of the low temperature level MD process can use alternative energy sources (e.g. solar and geothermal energy) and industrial waste heat as an energy source.

In an especially build test plant the suitability of MD for the treatment of pharmaceutical grade pure water is investigated...

Numerical simulation of heat and mass transfer in direct contact membrane distillation module

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...

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


G14 - Mist and Droplet Separation I

Day: 10 March 2022
Time: 13:00 - 14:15 h
Room 3

Session Chair:
Dr. Jörg Meyer

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 consisting of micro glass fibers and sometimes small amounts of synthetic fibers are widely applied in gas cleaning processes to separate liquid droplets from a gas flow (e.g. oil mists). When separated on the fibers of the filter media, the deposited oil can take different shapes dependent on the oil saturation, wettability, roughness and diameter of the fibers and fiber arrangement (e.g. axisymmetric barrel-shaped droplets, axially asymmetric clam-shell droplets or oil sails between adjacent fibers). To understand the initial state of the coalescence filtration process as well as the impact of the deposited oil structures within the filter matrix on the separation efficiency, it is essential to characterize these structures. Using X-Ray microtomography (µ-CT) and an artificial intelligence tool for segmentation, this work presents a novel approach to visualize, identify and analyze deposited oil structures down to sizes in the micrometer region. For a first time, the droplet distribution of deposited oil droplets on filter fibers of an oleophilic filter medium is presented. Furthermore, the liquid distribution of the oil in the direction of the flow, determined by calculating the volume fractions of the different phases (air, oil, fibers), is evaluated and discussed...

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...

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, L. Le Coq, IMT Atlantique ; M. Henry, S. Durécu, Séché Environnement, France

Nanomaterials (NMs) are increasingly used in industrial and consumer products. As a result, the likelihood that NMs will end up in the natural environment and adversely affect both the environment and human health have been on the rise. The lack of regulations on the end-of-life management of NMs indicates that they are currently been treated via recycling, composting, incineration and/or landfilling. A handful of studies have been conducted on the fate of NMs in waste incineration plants (WIP) particularly on the removal efficiency of nanoparticles 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. Traditionally, scrubbers are believed to be ineffective for the collection of particles less than 5 µm. However, recent studies established that under favorable operating conditions, scrubbers could be effective in collecting smaller particles.

The present study employs a design of experiment methodology - Box-Behnken Design (BBD) to evaluate the effects of the operating parameters of a spray scrubber on NPs collection efficiency...


G15 - Air Filtration III

Day: 10 March 2022
Time: 13:00 - 14:15 h
Room 4

Session Chair:
Dr. Qian Zhang

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...

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 the 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. The often bionic-looking optimized structures can be realized using additive manufacturing. In a further process step the structure can be coated. 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. The fibrous structure can also be electrostatically charge. In addition to the mechanical deposition mechanisms, charged particles are deposited by the Coulomb effect and any (charged or uncharged) particles by dielectrophoresis.

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 is established....


L15 - Flocculation / Filter Aids

Day: 10 March 2022
Time: 13:00 - 14:15 h
Room 1

Session Chair:
Dr. Pascal Ginisty

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 [1].

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 [2]. 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, T. Buchwald*, 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...


L16 - Characterization and Modelling and Pore Structures

Day: 10 March 2022
Time: 13:00 - 14:15 h
Room 5

Session Chair:
Prof. Urs A. Peuker

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 are carried out in the context of the AiF project IGF 19305 BR. The overarching goal is to expand comprehension of the interaction of several influence parameters such as steam temperature, boiling temperature of the VOC, filter cake resistance and height. The presentation shows the results of the investigations and demonstrates the advantages of processing VOC contaminated solids by SPF. Furthermore, it is shown that....

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; This leads 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...

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...


M07 - New Membranes

Day: 10 March 2022
Time: 13:00 - 14:15 h
Room 2

Session Chair:
Dr. Thomas Peters

Functional molecules on porous polymer membranes increase filtration performance

A. Braun*, qCoat GmbH; A. Schulze, Leibniz Institute for Surface Modification, Germany

The performance of commercially available membrane filters is improved by a one- step enhancement process, i.e. grafting with selected small functional molecules. These significantly reduce the tendency to membrane fouling, increase the flow rate, save energy and extend the service life of the refined membrane.

Using low energy electron beams (150-200keV), low molecular weight compounds dissolved in water are covalently bonded to the activated surface of a membrane. The molecules thus fixed permanently change the chemical and physical properties of the grafted membrane, while the morphology and pore size remain unchanged. Since the electron beam penetrates the membrane completely, the inner surface of the membrane, i.e. its pores, is also activated for the desired modification. Preferably, porous 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...


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

In this study, ZIF-8/GO (ZG) composites were prepared by the in-situ growth of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles onto the surface of graphene oxide (GO) nanosheets and were filled into PIM-1 matrix to fabricate ZIF-8/GO/PIM-1 thin-film nanocomposite (TFN) membranes for butanol recovery via pervaporation. The as-prepared ZG composites and ZIF-8/GO/PIM-1 TFN were characterized by various techniques. The results showed that ZIF-8 nanoparticles were uniformly grown on the surface of GO nanosheets. The 2D ZG has an average lateral flake size of 3.9 μm and a thickness of ~45 nm. The ZG composite has both good dispersity and compatibility in the PIM-1 matrix compared with ZIF-8 of GO alone and has continuous inner channels for butanol molecules. The size of supported ZIF-8 is ~24 nm, which is 73%...

Bilayer composite membranes: fabrication and optimization for improved gas permeability

S. Farrukh*, F. Yousaf, National University of Sciences & Technology (NUST); M. Younas, University of Engineering Technology, Pakistan, M. Ayoub, Universiti Teknologi Petronas, Malaysia

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...

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...

14:15h - Coffee Break


G16 - Mist and Droplet Separation II

Day: 10 March 2022
Time: 14:45 - 16:00 h
Room 3

Session Chair:
Dr. Jörg Meyer

Modeling and simulation of coalescence in the context of oil mist filtration using a distance map

D. Hoch*, J. Niessner, Heilbronn University of Applied Sciences, A. Weber*, Math2Market GmbH, 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...


G17 - Air Filtration IV

Day: 10 March 2022
Time: 14:45 - 16:00 h
Room 4

Session Chair:
Dr. Qian Zhang

Innovative silverized nonwovens with antiviral/antimicrobial performance for face mask and air filtration applications

J. Fan*, J. Levine, Folia Materials Inc. , USA

Folia Materials is a Boston-based materials science company that develops and supplies innovative and sustainable materials. Folia has a proprietary and patented nano-silver coating process technology that provides affordable antiviral and antimicrobial solutions for a cleaner, healthier, and safer world. Folia’s patented technology has led to successful commercialization in water filtration and antiviral face mask applications, leading to our next markets: self-disinfecting/odorless air filtration applications.

Folia’s patented nano-silver coating technology (IP patent: WO2017124057A1) was invented by Dr. Theresa Dankovich, based on fundamental research for her McGill University Chemistry Ph.D. This technology costs only a fraction of other metal coating technologies to make antiviral and antimicrobial nano-silver coated materials. Folia’s silverized nonwoven eliminates viruses and other pathogens on face masks and air filters, preventing virus cross contamination and improving indoor air quality. Third party test reports show the Folia’s silverized nonwoven reduces 99.97% of the SARS-CoV-2 virus within one hour (Virology Research Services, UK, test method ISO 18184), and reduces 99.99% of Staphylococcus Aureus and Klebsiella Pneumoniae (Microchem Lab, USA, test method AATCC-100). The Folia’s face masks are safe to wear, with silver levels one thousand times lower than the NIOSH particulate emission limits (NanoSafe lab, USA, test method NST-47 nanomaterials safety test).

These promising performance and safety test results give the Folia’s silverized nonwoven significant business potential in PPE and air filtration applications. We are focusing on premium self-disinfecting face mask and air filters applications, both long-term growing market segments, even after the COVID-19 pandemic. Antiviral face masks made with Folia’s silverized nonwoven reduces 99.97% of the SARS-CoV-2 virus within one hour and meets all ASTM F2100 medical face mask requirements, with >99% VFE, PFE, and BFE...

Nanofiltration must be combined with laminar vertical flow to minimize virus infection risk

A. Mayer*, J. Mayer, H. Burtscher, J. Czerwinski, T. Lutz, R. Mayer, NanoCleanAir GmbH; B. Rothen-Rutishauser, University Fribourg, J. Frey, University Bern, C. Lämmle, Combustion Flow Solutions GmbH, T. Rüggeberg, P. Specht, Fachhochschule Nord-West, Switzerland

A Corona infected person may emit more than 10 million viruses with each m3 of exhaled air and on the other hand the infection dose for his neighbour may be as low as 300-1000 viruses. Given these numbers, the infection risk in a room with one or more infected persons can not be sufficently redu- ced by periodic window ventilation or by cleaning a part of the air by mobile air cleaners but requires a continuous perfect virus elimination and avoidance of any lateral flow from the infected persons to their direct or distant neighbours.

This sounds utopic but can indeed be solved by body heat induced vertical laminar flow and venti- lation from floor to the ceiling, extracting the contaminated air at the ceiling and recycle it via a filter back to the floor. Filtration must be very close to 100%, deactivation of all deposited viruses does not tolerate any survivals and lateral risk must be below 1%.

Since the naket Corona virus has a size of 60-150 nm which is the typical range of particles emitted by combustion engines, the DPF (Diesel Particle Filter), a honeycomb type ceramic wall flow filter so far exclusively applied for combustion engines, might be an ideal soluton. These filters reach > 99% efficiency for soot particles of 10-500 nm and have attractive properties since their filtration surface is > 1 m2 per liter bulk volume, they can easily be cleaned in situ, if needed thermically desinfected, if required catalytically coated and have the life, the quality and low cost of a high vo- lume automotive product.

To test the bioaerosol filtration properties of these filters a research program was set up with virolo- gists and micro biologists of the universities Bern and Fribourg, using bacteriophages MS2 instead of SARS-CoV-2, a virus which is even smaller...

Masks characterization for nanoaerosol maximum retention and good breathability

T.C. Passos Pereira, B. de Araújo Lima, B. J. Chiaramonte de Castro*, 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

to 0.25 m/s. We tested 6 different masks, including one for non-professional use. The results exposed that using latex particles, the mask that obtained...


L17 - Innovative Separation Processes

Day: 10 March 2022
Time: 14:45 - 16:00 h
Room 1

Session Chair:
Prof. Ioannis Nicolaou

Development of membrane-woven-composite filter media for continuous cake filtration without gas throughput

N. Benz*, P. Lösch, K. Nikolaus, 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. Mechanical dewatering can significantly reduce the moisture in the filter cake and thus the energy required for thermal drying. 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 [1-2]. In this contribution, the investigations for the development of a filter media is presented, which can avoid this gas throughput....

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 – Simcondrill

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; O. Steffens, 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...


L18 - Optimization of Cake Filtration by Physico-Chemistry

Day: 10 March 2022
Time: 14:45 - 16:00 h
Room 5

Session Chair:
Dr. Harald Anlauf

Electrodewatering of different sewage sludges under constant electric current: impact of physico-chemical parameters on the dewaterability and the separation kinetics

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 (WWTP), and is mainly composed of water and the rest of its mass is the dry solids (DS). 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 to avoid the use of processes like thermal drying which consume high amounts of energy, that need to be limited.

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).
Previous studies have proposed an empirical model that reveals a relationship between the evolution of DS over time. This mathematical model includes a kinetics coefficient that is proportional to the sludge’s properties. This model was developed for EDW carried out under a constant electric current (I-EDW), unlike most of the studies presented in the literature where a constant voltage (U-EDW) is commonly used. Although less studied in the literature, the I-EDW mode remains an interesting operating mode as mentioned in some previous studies.

The objectives of this study are: (i) to evaluate the influence of the physicochemical parameters on the response of the process (notably the kinetics of the liquid-solid separation), and (ii) to incorporate the influencing parameters on the kinetics into the model...

Alkaline leaching behavior of zinc from Egyptian zinc ore and filtration performance at various pressure difference

D. Magdy 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,..

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