Photoinduced graft polymerization of acrylamide on polypropylene microporous membranes for the improvement of antifouling characteristics in a submerged membrane-bioreactor

Polypropylene hollow fiber microporous membranes (PPHFMMs) were surface-modified by the photoinduced graft polymerization of acrylamide (AAm). Structural and morphological changes on the membrane surface were characterized by attenuated total reflection-Fourier transform infrared spectroscopy (FT-IR/ATR) and field emission scanning electron microscopy (FE-SEM). Water contact angles of the membrane surfaces were also measured by the sessile drop method. Results of FT-IR/ATR indicated the successful graft polymerization of AAm onto the membrane surface. Water contact angle of the modified membrane decreased with the increase of the grafting degree. It showed 34.9 degrees for the modified membrane with a grafting degree of 278.4 wt.%, nearly 94 degrees lower than that of the nascent one. The antifouling characteristics of the PPHFMMs before and after surface modification were assessed by the filtration of activated sludge in a submerged membrane bioreactor for synthetic wastewater treatment. It demonstrated that after continuous operation for about 42 h, the flux recovery were 36.9, 63.7% and the relative flux ratio were 1.00, 1.32 for the nascent and modified PPHFMMs, respectively. (c) 2006 Elsevier B.V. All rights reserved.