Cross-Flow Microfiltration Characteristics of Streptococcus bovis in the Lactic Acid Fermentation Broth Produced by Fresh Cassava Roots

The cross-flow filtration characteristics of bacterial cells (S. bovis) obtained from a lactic acid fermentation broth of fresh cassava roots have been investigated in terms of specific cake resistance. The amount of particles accumulated on the membrane surface was evaluated using a cake filtration model. The effects of the operating conditions (transmembrane pressure, cross-flow velocity and cell concentration) on permeate flux, cake resistance and specific cake resistance were studied. The cake properties in cross-flow filtration were then compared to those in dead-end filtration. The specific cake resistance in the cross-flow filtration shows a higher value than in the dead-end filtration for almost the same cake compressibilities of about 1.0. The specific cake resistance increases with increasing cross-flow velocity and decreases with increasing cell concentration until reaching a concentration at which the specific cake resistance hardly changes. The increasing ratio of the specific cake resistance in the cross-flow filtration over the dead-end filtration is found to be independent of the transmembrane pressure and cell concentration.