FOULING MECHANISMS OF MEMBRANES DURING PROTEIN ULTRAFILTRATION

Fouling mechanisms of various ultrafiltration membranes were studied by high resolution field emission scanning electron microscopic (FESEM) examination of deposits formed during ultrafiltration of albumin protein. Fouling appears to be a surface phenomenon even for membranes that pass substantial amounts of protein. There was no FESEM observable protein within the pores. Two different types of foulant deposit were observed on the membrane surface; fouling by multilayer (cake) coating and fouling by aggregates of proteins. While aggregating type fouling was observed for membranes with high initial UF fluxes, those with lower initial UF flux showed cake formation. Aggregation may be initiated by rapid supersaturation of proteins above the pores due to high convective flows.