Per-and polyfluoroalkyl substances removal in water and wastewater treatment plants: overall efficiency and performance of adsorption

Per- and polyfluoroalkyl substances (PFAS) in aqueous environment attracted prodigious attention due to the deleterious effects and environmental persistence. Many studies suggested that adsorption is an economical and efficient method to remove PFAS and a variety of adsorbents were developed. However, few adsorbents were conveniently applicable in real wastewater treatment plants (WWTPs) or drinking water treatment plants (DWTPs). This review discusses the gap between laboratory results of PFAS removal by adsorbents and the realistic efficiency in water treatment. First, the overall performance of PFAS removal by conventional WWTPs and DWTPs was discussed. Second, PFAS removal efficiencies by different units along the treatment trains of DWTPs were compared and summarized. Third, benchtop results for the efficiency of different adsorbents including activated carbon, ion exchange resin, minerals, and metal-organic frameworks were reviewed. These studies collectively concluded that dissolved organic matter in water is the most consequential component influencing the absorptive removal of PFAS; PFAS removal efficacy was discounted in water enriched in organic matter due to competitive absorption. To obtain application implications, research on novel adsorbents of high selectivity is suggested to couple with realistic demonstration. As the battle with 'forever chemicals' escalates, this is a timely and insightful review to help future research efforts bridge the gaps between laboratory performance and realistic removal of PFAS applying adsorbents.