Yeast suspension filtration: Flux enhancement using an upward gas/liquid slug flow—application to continuous alcoholic fermentation with cell recycle

Abstract

This study deals with the use of an upward gas/liquid slug flow to reduce tubular mineral membrane fouling. The injection of air into the feedstream is designed to create hydrodynamic conditions that destabilize the cake layer over the membrane surface inside the filtration module complex. Experimental study was carried out by filtering a biological suspension (yeast) through different tubular mineral membranes. The effects of operating parameters, including the nature of the membrane, liquid and gas flowrates, and transmembrane pressure, were examined. When external fouling was the main limiting phenomenon, flux enhancements of a factor of three could be achieved with gas sparging compared with single liquid phase crossflow filtration. The economic benefits of this unsteady technique have also been examined. To investigate the possibility of long‐term operation of the two‐phase flow principle, dense cell perfusion cultures of Saccharomyces cerevisiae were carried out in a fermentor coupled with an ultrafiltration module. The air injection allowed a high and stable flux to be maintained over 100 h of fermentation, with a final cell concentration of 150 g dry weight/L. At equal biomass level, a twofold gain in flux could be attained compared with classical steady crossflow filtration at half the cost. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:47–57, 1998.

Enzyme Transmission during Crossflow Filtration of Yeast Suspensions Using Gas/Liquid Two‐Phase Flows

“…As much as a 140% increase in permeate flux was then achieved. This permeate flux behavior was in good agreement with previous studies of microfiltration with only yeast in the feed 4…”

“…One approach to reducing the deposition of suspended cells or particles on the membrane is to use improved fluid hydrodynamics. In this respect, several studies have pointed out the value of gas/liquid two‐phase flows to enhance the flux in ultrafiltration and microfiltration for various applications (drinking water production,1 biological treatment,2–4 and macromolecule separation5–8). In all these studies, the permeate flux enhancements were always significant, ranging from 20 to 320%, according to the application, the membrane type and the two‐phase flow pattern.…”

Novel Membrane Bioreactor with Gas/Liquid Two-Phase Flow for High-Performance Degradation of Phenol

“…In previous experiments relating to the alcoholic fermentation (Mercier et al, 1998), it has been observed that an important part of the fouling was due to the adsorption of medium components onto the filter. To evaluate the fouling capacity of the fresh medium, due notably to the chemical affinity of the phenol toward the carbon filter support, the bioreactor was filled with fresh culture medium (phenol concentration of 0.4 g L− 1 ) which was pumped through the system with complete recycling and for 3 h. No noticeable difference in the phenol concentration within the bioreactor was measured, indicating that the phenol does not adsorb selectively onto the membrane.…”

Continuous culture for the bioproduction of glycerol and ethanol by Hansenula anomala growing under salt stress conditions

“…Production rate is under control of the dilution rate: its increase results in increasing rates. However, the limit of the continuous process appears to be the relatively low cellular concentrations achieved, which may be overcome by cell recycling (Cheryan and Mehaia 1984;Mercier et al 1998), cell immobilization (Kourkoutas et al 2002;Lebeau et al 1998), or by the continuous extraction of the inhibitory produced ethanol (Honorato da Silva et al 1999).…”