keywords ACTIVATED-SLUDGE CROSS-FLOW ULTRAFILTRATION Engineering Engineering, Chemical Engineering, Environmental GAS/LIQUID 2-PHASE FLOW HOLLOW-FIBER MEMBRANE OF-THE-ART PERMEATE FLUX PROTEIN DENATURATION Physical Sciences SLUG FLOW Science & Technology TUBULAR MEMBRANE Technology Ultrafiltration WASTE-WATER TREATMENT Water Resources concentration polarization flux enhancement fouling gas sparging membrane bioreactor protein fractionation