The effects of osmotic pressure and fouling during a concentration process of BSA solutions by ultrafiltration

The contribution of membrane fouling and osmotic pressure on permeate flux decline and reduction was investigated during a series of ultrafiltration experiments of BSA solutions in a plate and frame tangential flow filtration unit equipped with a flat-sheet polysulfone membrane of 10,000 MWCO. Five concentrations, namely 4, 8, 18, 43 and 88 kg/m(3), were investigated in the order given. The osmotic pressure-adsorption model was selected for the determination of both contributions. The results show that the flux decline is determined by membrane fouling while flux reduction is controlled by membrane fouling and osmotic pressure at earlier stages and by osmotic pressure at later stages of the process.