The modification of poly(vinylidene fluoride)/polyethersulfone (PVDF/PES) blend membranes was carried out by adding polyvinyl alcohol (PVA) to improve their antifouling ability. The physicochemical characteristics of the membranes in terms of porosity, contact angle, pure water flux, critical flux and fouling rate were systematically analyzed. The extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory was used to assess the antifouling ability of the modified membranes, and the membrane's long-term performance was also evaluated in a pilot-scale submerged anoxic/oxic membrane bioreactor for wastewater treatment. The results showed that the hydrophilicity and permeability of PVDF/PES blend membrane were efficiently improved by adding 0.3% PVA. The increase of critical flux and the decrease of fouling rate for the modified membrane were also observed in batch filtration experiments. XDLVO analysis indicated that the addition of PVA significantly improved the cohesion free energy of the membranes. The energy barrier between soluble microbial products and membrane surfaces was increased, which therefore reduced the adsorption of membrane foulants. The long-term filtration process also demonstrated that the antifouling ability of PVDF/PES membrane modified by 0.3% PVA was significantly enhanced. The study offers an effective way to enhance membrane antifouling ability of PVDF/PES membrane through the addition of PVA additives. (C) 2014 Elsevier B.V. All rights reserved.