Advanced reduction processes (ARPs) have emerged as a promising method for destruction of persistent perand polyfluoroalkyl substances (PFAS) in water due to the generation of short-lived and highly reductive hydrated electrons (e aq − ). This study provides a critical review on the mechanisms and performance of reductive destruction of PFAS with e aq − . Unique properties of e aq − and its generation in different ARP systems, particularly UV/sulfite and UV/iodide, are overviewed. Different degradation mechanisms of PFAS chemicals, such as perfluorooctanoic acid (PFOA), perfluorooctanesulfonate (PFOS), and others (e.g., short chain perfluorocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs), per-and polyfluoro dicarboxylic acids, and fluorotelomer carboxylic acids), are reviewed, discussed, and compared. The degradation pathways of these PFAS chemicals rely heavily upon their head groups. For specific PFAS types, fluoroalkyl chain lengths may also affect their reductive degradation patterns. Degradation and defluorination efficiencies of PFAS are considerably influenced by solution chemistry parameters and operating factors, such as pH, dose of chemical solute (i.e., sulfite or iodide) for e aq − photoproduction, dissolved oxygen, humic acid, nitrate, and temperature. Furthermore, implications of the stateof-the-art knowledge on practical PFAS control actions in water industries are discussed and the priority research needs are identified.

This study aimed to probe the interactions of hydrated electrons (eaq –) and perfluorooctanoic acid (PFOA)-laden ion-exchange (IX) resins in the presence of natural organic matter (NOM). PFOA and Suwannee River NOM-loaded resins were prepared through the removal of PFOA in simulated natural water with weak-base anion (WBA) resins (IRA67). Adsorption tests reveal that sorbed NOM was much more abundant than cosorbed PFOA, highlighting the role of NOM in resin saturation. Ensuing UV/SO3 2– treatment of PFOA/NOM-laden resins (pH 10.0) under a dissolved oxygen-free condition indicates that eaq – generated could effectively degrade sorbed and aqueous PFOA, the latter of which derived from desorption of PFOA due to pH increase. Finally, cyclic adsorption-UV/SO3 2– treatment tests demonstrate that the PFOA sorbed on the WBA resins could be mostly degraded over six cycles. However, eaq – could not effectively decompose cosorbed NOM, resulting in a gradual decrease in the recovered PFOA adsorption capability with the cycle number. This study spotlights that eaq – can decompose PFOA sorbed on the WBA resins in the presence of NOM. The UV/SO3 2– process, when jointly used with appropriate strategies for mitigating cosorbed NOM, can enable a promising on-site resin regeneration process with PFOA degradation while producing a relatively small volume of regenerant waste.

The frequency and magnitude of natural disasters (e.g. hurricanes) have increased globally over the past century.

Clean water is vital amid a disaster or disease outbreak-related emergency. This study aimed to evaluate an inventive emergency water treatment (EWT) process with the joint use of ferrate(VI) and...