A Review of Research Advances on Treatment Technologies for Per- and Polyfluoroalkyl Substances (PFAS) in Wastewater

Per- and polyfluoroalkyl substances (PFAS) have emerged as global environmental pollutants due to their extreme chemical stability, environmental persistence, and potential ecological risks. Despite their widespread industrial applications, the recalcitrant nature of PFAS leads to continuous accumulation in water bodies, soils, and organisms, posing significant environmental and health concerns. This review summarizes recent advances in conventional (e.g., adsorption, membrane separation, electrochemical oxidation) and emerging (e.g., hydrothermal alkaline treatment, plasma technology, mechanochemical degradation) PFAS wastewater treatment technologies, focusing on their mechanisms, applicability, and research progress. The review aims to analyze the degradation principles, treatment efficiency, and scalability of existing technologies while providing future optimization recommendations. Adsorption offers cost-effectiveness advantages; membrane separation avoids chemical usage; electrochemical oxidation operates under mild conditions; pyrolysis achieves complete mineralization; hydrothermal alkaline treatment demonstrates notable environmental friendliness. However, these technologies still face multiple challenges, including secondary pollution risks, high energy demands (e.g., pyrolysis and flash Joule heating), limited efficiency for short-chain PFAS (e.g., foam fractionation), and low technological maturity (e.g., ultrasonic and biodegradation). From an engineering perspective, adsorption and membrane separation have reached commercialization, while electrochemical oxidation, Fenton oxidation, and ozonation are at pilot-to-demonstration stages. Most other technologies remain confined to laboratory research. Based on current limitations, future development should prioritize: (1) novel functional materials (e.g., pH-adaptive catalysts and hybrid membranes), (2) process optimization and integration, (3) engineering improvements (e.g., continuous reactor design and energy consumption control), and (4) comprehensive environmental risk assessment. Breakthroughs in these areas will advance PFAS treatment toward higher efficiency, cost-effectiveness, and environmental sustainability.