How to deal with PFAS in urban water systems? A combination of removal strategies, fate modelling and risk assessment

Per- and polyfluoroalkyl substances (PFAS) are persistent emerging contaminants of increasing environmental and human health concern. Urban water systems face significant challenges in managing PFAS contamination due to multiple sources, including industrial and municipal wastewater treatment plant (WWTP) effluents, stormwater runoff, and groundwater infiltration. While the revised Urban Wastewater Treatment Directive (UWWTD) does not explicitly address PFAS, stringent regulations on PFAS concentrations in drinking water necessitate effective mitigation strategies. This study integrates laboratory, pilot-scale, and full-scale assessments to evaluate PFAS removal in both WWTPs and drinking water treatment plants (DWTPs). Four case studies were analyzed, focusing on PFAS occurrence, fate, and removal through adsorption and ozonation. A modelling framework was developed to predict PFAS transport and assess environmental risks under different water management scenarios. Results indicate that short-chain PFAS, despite lower toxicity, pose greater removal challenges due to their hydrophilic nature. Adsorption efficiency was found to be highly dependent on activated carbon characteristics, with pre-ozonation improving PFAS removal. Breakthrough analysis demonstrated that larger pore sizes enhance retention of long-chain PFAS, while short-chain PFAS remain difficult to capture. The findings highlight the need for optimized PFAS management, combining targeted removal technologies and regulatory interventions. This research provides a valuable framework for assessing mitigation strategies, guiding water utilities in implementing effective solutions to reduce PFAS contamination and associated risks in urban water systems.