MICROFILTRATION OF PROTEIN SOLUTIONS AT THIN-FILM COMPOSITE MEMBRANES

An experimental study of the interaction of the enzyme yeast alcohol d ehydrogenase (YADH) with polysulfone thin film composite microfiltrati on membranes (Dow-Danmark) has been carried out. It was found that the membranes adsorbed only approximately 3/4 of a monolayer of the enzym e under the conditions studied. Even so, under filtration conditions, the membrane permeation rate decreased continuously with time. This de crease in permeation rate was due neither to concentration polarisatio n nor to protein adsorption alone. However, it could be quantified usi ng the standard blocking filtration law, which describes a decrease in pore volume due to deposition of protein in the interior structure of the membrane. Reversal of the membrane, so that the supporting matrix faced the feed solution, gave more stable permeation rates. Implicati ons for the microfiltration of industrial fermentation broths are disc ussed.