Prospect and Challenges of Tight Ultrafiltration Membrane in Drinking Water Treatment

Ultrafiltration (UF) membrane for drinking water treatment has been consistently modified to improve the selectivity towards trace organic compounds (TrOCs) and maintain the flux stability for long-term application. Currently, the tight UF membrane has been developed to answer the challenges of conventional UF membranes. With small pore size (300 - 5000 Da), the tight UF showed higher TrOCs rejection and lower irreversible fouling than the conventional UF membranes. Two methods have been proposed to fabricate the low molecular weight cut off (low-MWCO) UF membranes, i.e. blending membrane solution with fillers (nanoparticles or volatile solvent) and modifying membrane surface layer by chemical or plasma grafting method. Low water flux and high operating pressure are some challenges to be solved during the application of the tight UF membrane. Hence, the development of tight UF membrane with low-MWCO pore size has focused on improving flux while maintaining high selectivity. In this paper, the development and prospect of tight UF membrane will be reviewed. Challenges during the application of low-MWCO UF membrane for water treatment and methods to solve the challenges will be discussed. (paper)