Filtrate flux and sieving characteristics of virus filtration membranes

Virus filtration is increasingly used in the biopharmaceutical industry, but capacity and fouling remain problematic. Experimental studies were conducted in dead-end, stirred filtration cells with Viresolve 180 polyvinylidene fluoride membranes using the protein bovine serum albumin. Data were obtained for membranes in two different flow orientations, with the selective "skin" layer oriented on either the upstream surface or downstream relative to the fluid flow. Compaction of the substructure occurs when the skin layer is downstream, leading to a significant increase in membrane resistance. Concentration polarization in the bulk solution or membrane substructure caused a substantial increase in the protein sieving coefficient, with this effect being greatest when the flow entered through the substructure. Fouling is primarily due to the deposition of large protein aggregates. The effect of this fouling on the flux was reduced when the skin layer was oriented downstream since the substructure acted as a prefilter. These results demonstrate that the membrane morphology and orientation play a critical role in determining the overall performance of virus filtration membranes.