Crossflow filtration of yeast broth cultivated in molasses

Abstract

A broth of yeast cells cultivated in molasses was crossfiltered with a thin-channel module. The permeation flux gradually decreased at a constant cell concentration. The flux was much lower than that obtained for yeast broth cultivated in yeast extract, polypeptone, and dextrose (YPD) medium during the filtration. The flux did not depend on the membrane pore size (0.45 to 5 mum). The steady-state flux was one-twentieth that calculated for a cake filtration mode from the amount of cake per unit filtration area and the specific resistance of the cake measured in a dead-end filtration apparatus. The lower flux was due to small particles (most of which were less than 1 mum in diameter) in the molasses. The mehanism of crossflow filtration of broths of yeast cells cultivated in molasses was clarified by analysis of the change in flux with time and observations with scanning electron microscopy. At the initial stage of crossflow filtration the yeast cells and particles from the molasses were deposited on the membrane to form the molasses were deposited on the membrane to form a cake in a similar way to dead-end filtration. After the deposition of cells onto the membrane ceased, the fine particles from molasses formed a thin layer, which had higher resistance than the cake formed next to the membrane. The backwashing method was effective to increase the flux. The flux increased low when the pore size was 0.45 to 0.08 mum, but using larger pores of 3 to 5 mum it returned almost to the bases line. (c) 1994 John Wiley & Sons, Inc.

Flocculation of biological cells: Experiment vs. theory

“…A number of investigators Kim et al, 2001;Dharmappa et al, 1992;Wickramasinghe, 1999;Huisman et . al., 1999;Tanaka et al, 1994;Chellam and Wiesner, 1998 have shown that, for polydisperse feeds, the presence of smaller particles often leads to lower permeate fluxes during microfiltration than would be expected based on the average particle size. Thus, determining the properties of the particle-size distribution after flocculation is essential in order to predict the effect of flocculation on the permeate flux.…”

Dead-end filtration of yeast suspensions: Correlating specific resistance and flux data using artificial neural networks

“…Solid medium components may cause cake clogging [17] while concentration polarisation of soluble components may also be significant if solute rejection occurs [18]. Both of these phenomena may increase the effective specific cake resistance.…”

Effect of Flocculation on Critical Flux during Crossflow Microfiltration of Bentonite Suspensions

“…This can have a significant effect on the critical flux, for instance the SIDM predicts a critical flux dependence on particle diameter to the power of 4/3. A number of other investigators (15,(21)(22)(23)(24)(25) have either shown or suggested that the presence of smaller particles often leads to lower permeate fluxes during microfiltration than may be expected based on the mean particle size.…”