Selected advanced water treatment technologies for perfluoroalkyl and polyfluoroalkyl substances: A review

Numerous perfluoroalkyl and polyfluoroalkyl substances (PFASs) have been widely found in both wastewater effluent and drinking water worldwide; thus, these chemicals have become a global issue as emerging organic contaminants. Aliphatic PFASs with saturated carbon-fluorine bonds appear to be incompletely removed during conventional chemical/physical (coagulation, flocculation, sedimentation, and filtration) and biological (activated sludge) treatment processes. However, they can be effectively removed by advanced treatment technologies such as sorption, membranes, and oxidation. Thus, it is essential to understand the removal mechanisms of various PFASs during these advanced treatment processes, in particular because the physicochemical characteristics of various PFASs impose difficult challenges regarding determining the transport and fate of these compounds in aqueous solution. Several review studies have been conducted to evaluate the removal of PFASs in various drinking water treatment and environmental remediation processes. However, to the best of our knowledge, very little information is still available on the effects of water quality conditions on the removal of PFASs. Therefore, in this study, we comprehensively summarize the recent state of knowledge of selected advanced water treatment technologies (sorption, membrane, and oxidation) for the removal of PFASs under different water quality conditions (e.g., pH, temperature, background ions, natural organic matter, and solute concentration).