Ultrafiltration permeate flux decline prediction for gel layer forming solutes using monotubular ceramic membranes

Experimental results on permeate flux decline with time obtained from ultrafiltration tests were compared with those predicted by means of Song and Elimelech's model. Feed solutions consisted of aqueous solutions containing 15 g/L of polyethylene glycol 35 kg/mol. All model parameters were theoretically estimated, except the gel layer concentration that was estimated as described by Lee et al. Experimental tests were performed with monotubular ceramic Tami MSKT membranes from Tami Industries (France). TMP (0.2, 0.3, 0.4 and 0.5 MPa) and crossflow velocity (1, 2 and 3 m/s) were varied. Permeate flux slightly decreased with time for all the experimental conditions tested. The best predictions were obtained for long time scales for a crossflow velocity of 1 m/s. For those experimental conditions the probability of gel layer formation on the membrane surface is the highest. For short time scales, model predictions showed a rapid initial permeate flux decline that was not experimentally observed because it may occur instantly before the first permeate was collected.