High-pressure membrane filtration processes for separation of Per- and polyfluoroalkyl substances (PFAS)

The development of remediation technology for Per- and poly-fluoroalkyl substances (PFAS) has become one of the nation's top research priorities as adverse impacts to environmental and human health have been increasingly identified. Of various water treatment routes, high-pressure membrane processes such as nanofiltration (NF) and reverse osmosis (RO) are considered most promising by virtue of the excellent rejection of both short- and long-chain PFAS and the proven technological maturity demonstrated with various water sources. Consequently, research activities have rapidly increased to accommodate research needs to advance NF and RO processes targeting PFAS removal from the aquatic environment. Therefore, the present review highlights recent findings in the areas of (a) rejection mechanism for PFAS, (b) the effects of membrane property and the water matrix, (c) challenges in high-recovery operation due to adsorption of PFAS and subsequent membrane fouling or scaling, and (d) complementary technologies to overcome the significant challenge to manage or treat a large volume of the waste stream from NF and RO. Overall, this review emphasizes research opportunities to develop engineering solutions that can be implemented in practical water treatment applications to address the imminent threat from PFAS.