Influence of Particles on the Roller Discharge of Thin-Film Filtration without Gas Throughput

Abstract

If fine and compressible particle systems need to be separated, the ground layer compaction caused by the compacting of the filter cake leads to high flow resistances. Thin-film filtration is a suitable method to avoid the limiting effect of the filter cakes. Gas-impermeable filter membranes prevent shrinkage cracking, which can occur during demoisturing of the filter cakes. Titanium dioxide and baker's yeast are used as model particle systems, which are present in different concentrations and are filtered with track-etched membranes in different particle-to-pore size ratios. The parameters determined during the investigation are the residual moisture, the specific solid mass, and the completeness of the discharge. Filtration causes progressive blocking of the membrane pores, resulting in filter medium resistances that are increased by up to a factor of 175. Metabolism of yeast can cause bubbles to accumulate on the membrane and decreasing the free filter area. Without regeneration the specific solid mass flow rate is reduced by 61 % for titanium dioxide and by 13 % for yeast under ideal conditions of this experimental study.