Ultrafiltration membranes are largely applied as macromolecular solutes and heavy metal ion separation from aqueous streams. Cellulose acetate and polycarbonate blend ultrafiltration membranes were prepared by the phase inversion technique in 100/0, 95/5, 85/15 and 75/25% polymer blend compositions in the absence and presence of a polymeric additive, poly(ethylene glycol) 600, at different additive concentration and were used for the rejection of proteins trypsin, pepsin, egg albumin (EA) and bovine serum albumin (BSA). The toxic heavy metal ions copper, nickel, zinc and cadmium from dilute aqueous solutions were subjected to rejection by the blend membranes. Permeate flux studies of proteins and metal ions were performed simultaneously with the rejection experiment. The rejection and permeate flux of the blend membranes were compared with those of pure cellulose acetate membranes. (c) 2008 Elsevier B.V. All rights reserved.