Filtration characteristics in dead-end microfiltration of living Saccharomyces cerevisiae cells by alumina membranes

Abstract

Dead-end microfiltration of live Saccharomyces cerevisiae (yeast) suspensions of low concentration was carried out in a stirred membrane cell and corresponding permeate flux as a function of trans-membrane pressure (TMP) and membrane pore size were estimated. The deposition mechanism on the membrane surface and/or into its porous structure was analyzed in terms of various kinetic models, viz., cake filtration, standard blocking and complete pore-blocking models. It was seen that an initial intense flux decline due to external blockage followed by an internal deposition (partially retained cells) or the formation of a cake. Steady state permeate fluxes increased with the increase in the pore size of the membranes and decreased with the increase in yeast concentrations. In the present study, linear regression analysis of the filtration data showed that β values (filtration characteristic constant) were in the same order of magnitude as those of theoretical values. It was found that specific cake resistance increased with the increase in the TMP. The β values were found to vary in the range of –0.5 to 1.4. Compressibility factor (n) was found to be 0.853. According to the values, it has been found that all the above filtration mechanisms were simultaneously occurring rather than contributing individually.