Correlations of filtration flux enhanced by electric fields in crossflow microfiltration.

Abstract

The steady state filtration flux in electrically-enhanced crossflow microfiltration is estimated using a correlation equation proposed for several kinds of suspensions. Baker's yeast and Rhodotorula glutinis were used as model samples of microbial cells, and PMMA particles were used as samples of non-living solids. Application of the electric field in crossflow microfiltration is a useful method for improving the filtration flux of these samples. High flux levels for the cells were achieved when an electric field above 3000 V/m was applied. The effect of the electric field in increasing the filtration flux of the steady state was analyzed theoretically using a force balance model where the viscous drag force, FJ, the electrophoretic force, FE, and the re-entraining force, FB, were considered to act on a particle on the membrane surface under a steady state of filtration, respectively. From force balance analysis, it is found that on application of an electric field, the electro-osmotic effect can be neglected in the present study, so that the filtration flux of the steady state, JES, can be presented by, JES = UEPE + J0S where UEP is the electrophoretic mobility of particles and E is the electric field applied. J0S is the filtration flux in the absence of an electric field, which is correlated with the operating parameters for suspensions tested.