Colorado School of Mines
Raul Tenorio is a PhD student at the University of Illinois at Urbana-Champaign and is currently performing research as a visiting scholar in the Civil and Environmental Engineering department at Colorado School of Mines. His current research involves the treatment of per- and polyfluoroalkyl substances using photochemical processes. He received a B.S. degree in Civil Engineering from the University of Texas at Austin and an M.S. degree from the University of Illinois at Urbana-Champaign in Environmental Engineering.
Effects of water matrix on UV-sulfite treatment of per-and polyfluoroalkyl substances (PFAS) in groundwaters impacted by aqueous film forming foam (AFFF)
Studies have shown widespread contamination of per- and polyfluoroalkyl substances (PFAS); one point source of contamination being the use of aqueous film forming foam (AFFF) during fire training activities at military and municipal sites. While effective at extinguishing fires, AFFF contains PFAS, known to be highly recalcitrant and bioaccumulative. In 2016, a health advisory limit (HAL) of 70 ng/L was set by the EPA for perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), combined. Current estimates indicate that millions of people in the U.S. are exposed to PFAS levels above HALs. Because natural biological/abiotic processes cannot effectively degrade PFAS and conventional treatment technologies can become cost-prohibitive, the development of alternative PFAS abatement strategies is crucial. Photochemical approaches such as the UV-sulfite process (i.e., UV254 + Na2SO3) have been explored recently for PFAS destruction. The production of short-lived but highly reactive hydrated electrons (eaq-; E0 = -2.9 V) during UV-sulfite treatment has shown promising reactivity with PFOS and PFOA. However, little is known about treatment efficacy in (1) complex PFAS mixtures found in AFFF or (2) AFFF-impacted groundwater with varying geochemical conditions. In this study, the UV-sulfite process was applied to AFFF-impacted groundwaters to investigate the efficacy of PFAS treatment in relevant geochemical matrices. LC-QTOF-MS was used to quantify PFAS for a diverse set of compound classes. The effects of dissolved organic matter (DOM), cations (e.g., Ca2+), and oxyanions (e.g., nitrate) will be discussed. Initial results show that PFOS and perfluorocarboxylic acids (PFCAs, including PFOA) are readily degraded during treatment, indicating UV-sulfite treatment is a promising strategy for treating PFAS relevant to the EPA HALs. Additionally, results show PFAS reactivity can be enhanced or diminished in groundwater matrices depending on compound class. Insights and challenges for future water treatment will also be discussed.