Protein fouling of asymmetric and composite microfiltration membranes

Although many microfiltration membranes have asymmetric or composite struct ures, there is little understanding of the effects of this multilayer struc ture on fouling. A new model was developed that explicitly accounts for flu id flow through two layers: an upper layer with noninterconnected pores and a substructure with highly interconnected pores. Initial fouling occurs by pore blockage, with a cake layer then forming over those regions covered b y foulant. Model calculations are in excellent agreement with experimental data for the filtrate flux and resistance during constant-pressure filtrati on of bovine serum albumin. The highly interconnected pores within the supp ort structure reduce the rate of flux decline by shunting more fluid throug h the open pores. The extra resistance provided by the support also reduces the relative importance of the protein deposit. The results provide import ant insights into the effects of pore morphology on membrane fouling.