Remediation of water from per-/poly-fluoroalkyl substances (PFAS) - Challenges and perspectives

Per-/poly-fluoroalkyl substances (PFAS) are an emerging class of environmental contaminants used as additives to either enhance the thermo-chemical stability of products or alter the properties of surfaces. PFAS are amphiphilic molecules, composed of fluoro-alkyl chains terminated by specialized functional groups such as carboxylic, sulphonic acids, phosphates, sulphonamides, and betaines; offering surfactant-like behavior, and making them highly persistent and mobile across all environmental compartments. The treatment of PFAS contaminated water remains very complex due to the typically low concentrations and because of the complexity of the wastewater matrix in which PFAS are present. Exposure to trace amounts of PFAS can cause severe health impacts across all life forms. Trains of treatment or removal techniques must be employed to achieve higher removal rates. This review assesses existing methods for PFAS capture, concentration, and degradation from wastewaters. The performance and selectivity, as well as scalability and cost-effectiveness, of these techniques are critically compared while operating limitations, as well as emerging solutions, are presented to evaluate the combinatorial benefits of tandem operations for successful PFAS remediation. The discussion is then focused on prospects for more cost-effective and scalable PFAS remediation solutions enabling the treatment of dilute and complex water matrices, required to deal with these extremely persistent pollutants.