Crossflow microfiltration of low concentration-nonliving yeast suspensions

Abstract

Crossflow microfiltration of low concentration-nonliving yeast suspension was studied and effects of transmembrane pressure drop (Δ P), membrane pore size and crossflow velocity on the membrane fluxes have been investigated. Filtration mechanism was explained by various flux decline models such as standard, intermediate, complete blocking and cake filtration. It was shown that permeate flux decay could be divided into three distinctive regions such as constant, rapid flux decay and slow flux decay periods by using relations of J( t)– t, t/ V– V and V– t on the same plot. It was concluded that flux decline model fit to intermediate blocking model at the beginning of the filtration and then classical cake filtration became dominant filtration mechanism. It was found that specific cake resistance increased with increasing Δ P. Compressibility coefficient ( n) was calculated to be 1 and 0.39 for crossflow and dead-end filtration modes, respectively. Steady-state permeate fluxes increased with membrane pore size and crossflow velocity, and decreased with increasing yeast concentration. It was determined that pseudo-gel concentration on the membrane surface was 45 g/l and it was independent from crossflow velocity and membrane pore size.