A combined pore blockage and cake filtration model for protein fouling during microfiltration

Previous studies of protein fouling during microfiltration have shown signi ficant discrepancies between filtrate flux data and predictions of the clas sical pore blockage, pore constriction, and cake filtration models. A new m athematical model was developed for the filtrate flux which accounts for in itial fouling due to pore blockage and subsequent fouling due to the growth of a protein cake or deposit over these initially blocked regions. The mod el explicitly accounts for the inhomogeneity in the cake layer thickness ov er different regions of the membrane arising from the time-dependent blocka ge of the pore surface, The model was shown to be in excellent agreement wi th experimental data obtained during the stirred cell filtration of bovine serum albumin solutions through polycarbonate track-etched microfiltration membranes over the entire course of the filtration. The model provides a sm ooth transition from the pore blockage to cake filtration regimes, eliminat ing the need to use different mathematical formulations to describe these t wo phenomena. In addition, the model provides the first quantitative explan ation for some of the unusual observations reported previously in investiga tions of protein microfiltration. The results provide important insights in to the underlying mechanisms of protein fouling during microfiltration. (C) 2000 Academic Press.