A comprehensive overview on the occurrence and removal of per- and polyfluoroalkyl substances through adsorption and biodegradation

Abstract

Per- and polyfluoroalkyl substances (PFAS), known for their exceptional stability and hydrophobic properties, have become prominent environmental contaminants due to their persistence and toxicity. This review provides a comprehensive analysis of PFAS occurrence in groundwater and surface waters, their degradation by various microbial species and the effectiveness of different adsorbents in PFAS removal. Microbial degradation is a cost-effective and environmentally friendly method for PFAS removal, with aerobic biotransformation being more widely studied. Microbial strains, including Acidimicrobium sp. A6, Pseudomonas, and Gordonia sp. showed sustainable reduction (up to 99 %) in PFAS concentrations. Under aerobic and anaerobic conditions, microbial mechanisms differ significantly, requiring specific microbial strains or engineered systems to break the strong C-F bonds. Various adsorbents, such as carbonaceous materials, ion exchange resins, and other synthetic materials, have been used to remove PFAS from water. Positively charged adsorbents were more effective in removing PFAS than neutral or negatively charged ones. Ion exchange resins outperform other adsorbents in removing both long and short-chain PFAS. This review outlines significant research needs, including the need to understand the complex interactions between dissolved organic matter and PFAS removal, as well as the potential of advanced materials to improve adsorption processes. Future research should focus on scalable, cost-effective, and environmentally sustainable methods to reduce PFAS contamination and provide safer water resources for future generations.