Investigation about cohesion and adhesion in backwashing filtration based on penetrometry and tension tests

Y. Feith*, P. Morsch, H. Anlauf, H. Nirschl, Karlsruhe Institute of Technology (KIT), Germany; P. Ginisty, Institut de la Filtration et des Techniques Séparatives (IFTS), France

Various equipment in liquid-solid separation (filter press, leaf filter, candle filter, rotary drum filter, nutsche filter, filtering centrifuge, cartridge filters and more) use filter cloth to retain particles as valuable particles or contaminants. An incomplete cake discharge and/or filter cloth cleaning after the filtration process causes yield losses, cycle time increase, irregular cake formation, increase cleaning liquors volumes, decrease of filter cloth lifetime. As cake filtration, washing or deliquoring, cake discharge and filter cloth cleaning/regeneration is a key step of the process cycle time. The choice of adapted operating conditions such as filter cloth characteristics, suspension pretreatment to modify sludge properties (e.g. granulometry, morphology), pressure, flow rate and further are necessary to decrease the duration of these operations to a minimum.

To describe the detachment behaviour, measurements of the cohesion in the filter cake are carried out on the basis of penetrometry. These measurements are accompanied by tensile tests, which aim at measuring the adhesion between tissue and the first particle layers. Framework of this investigation is to compare the adhesion between different filter cloth – particle combinations (weave type, fiber diameter, mesh size, particle size/shape/distribution and more) and the cohesion of different particle systems (particle size/shape/distribution and more). Based on this, the ad-/ and cohesion measurements shall be used to describe the regeneration through filter cake discharge on a laboratory filter candle test setup. Main task is to found out the mechanism of discharge based on strength measurements.

The presentation includes the presentation of the project, the measuring equipment and test materials used (filter fabric and particle system) as well as the current status of the project. In addition to the measurements of co-/adhesion, selected backwashing processes in the chamber and backwash filter will be demonstrated...

Session: L20 - Enhancement of Backwashing and Cake Filtration Performance
Day: 24 October 2019
Time: 14:45 - 16:00 h

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