Problem: The City of Tucson water treatment plant was treating 1,4-dioxane using a UV advanced oxidation process with eight granular activated carbon vessels for peroxide quenching. Water quality testing revealed significant PFAS contamination, requiring the plant to expand capacity for the longer empty-bed contact time PFAS removal requires.

Solution: AqueoUS Vets provided the treatment and delivery systems, which included two 12-foot-diameter lead-lag granular activated carbon systems, with two pressure vessels per system. The systems have an empty bed contact time at 930 gpm of 5 minutes per vessel, and 10 minutes per system.

Result: While there are no state regulatory limits for PFAS in Arizona, the EPA issued interim updated health advisory levels for PFOA and PFOS in June 2022, with updates expected in early 2023. The health advisories are currently 0.004 parts per trillion for PFOA and 0.02 ppt for PFOS. Since July 2020, the city has been removing PFAS to non-detectable levels. 925-331-0573; www.aqueousvets.com