Membrane fouling during cross-flow microfiltration of Polyporus squamosus fermentation broth

The application of microfiltration to biological systems is hindered by membrane fouling that results in a decrease in the filtrate flux and solute transmission with time. In this work, the effects of transmembrane pressure, cross-flow feed velocity, biomass structure and feed composition, on membrane fouling during cross-flow microfiltration of Polyporus squamosus fermentation broth, were investigated. The results of cross-flow trials with 0.2 mum aluminum oxide membrane showed the existence of the optimal operation transmembrane pressure and cross-flow velocity, in respect of membrane fouling, for examined range of operation conditions. It was noticed that the process of membrane fouling was moved from a predominantly surface layer phenomenon to internal membrane fouling as the cross-flow velocity was increased. Comminution of the fungal biomass prior to microfiltration to reduce particle size showed a beneficial effect on the transient flux. The steady-state flux and the transmission of solutes were not significantly affected by the biomass comminution. The observations of the filtrate flux and the transmission of solutes indicated a decrease in the rate of fouling with decreasing content of soluble components with large molecular weights in the feed. (C) 2001 Elsevier Science B.V. All rights reserved.