Treatment and Mitigation of PFAS in Drinking Water | AAAS EPI Center
processes in PFAS applications to reduce the load of other compounds on the media, improving PFAS removal capabilities. Also, the spent GAC media will contain adsorbed PFAS and must be disposed of properly. Spent media are often disposed of in landfills or sent to an incineration facility. Research is ongoing to characterize PFAS behavior in air emissions and determine the conditions required for the destruction of PFAS during high- temperature incineration. In addition, GAC units may need to be periodically cleaned by reversing flow through the filter — a process known as “backwashing.” 23 Water used during backwash requires disposal and may contain PFAS. WWTPs that would typically accept GAC backwash waste may be reluctant to receive this waste if PFAS are present. Compared to other PFAS treatment methods, GAC requires a moderate capital and operating cost . GAC can be a cost-effective PFAS removal alternative, but it is important to consider PFAS removal goals and influent water quality that may impact GAC’s ability to adsorb PFAS. Ion Exchange (IX) Is Considered a Best Available Technology for PFAS Removal and Provides Secondary Water Quality Benefits IX is an established drinking water technology that utilizes anionic (negatively charged) or cationic (positively charged) resin beads to attract contaminants of interest out of the water. Unlike PAC and GAC, which remove compounds through adsorption, IX exchanges one compound for another benign compound. Compounds that are removed leave the water and attach to the resin, while a harmless compound originally contained in the resin leaves the resin and enters the water. Anionic resins are most often used for water softening (e.g., removing calcium and magnesium), and to remove PFAS, TOC, and/or color. PFAS-selective resin has been developed, although effectiveness varies for different types of PFAS and research is ongoing 24 . Figure 3 shows an IX vessel and IX resin beads. Figure 8 - IX Vessel (Left) and IX Resin (Right)
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