The overall objective of this project is to advance a SERDP-validated treatment technology for destroying per- and polyfluoroalkyl substances (PFAS) present in concentrated liquids, thereby allowing liquids to be reused in the treatment process or discharged to the environment. This project will provide field-scale performance data treating a concentrated PFAS liquid stream. The project will also provide a basis for assessing technology performance treating other waste streams including regenerable ion exchange resin concentrate, foam fractionate, reverse osmosis reject, and aqueous film-forming foam (AFFF).

The technology consists of ultraviolet activated silica-based granular media (UV/SGM) that contains titanium dioxide as a photocatalyst. When configured as a packed bed reactor, UV/SGM can treat liquids containing high concentrations (i.e., parts per million) of PFAS mixtures to non-detectable concentrations under low flow conditions. Work conducted under SERDP project ER19-1403 characterized treatment kinetics for different SGM catalysts as well as basic and acidic amendments to enhance mechanisms for degrading various PFAS and their precursors. Fluoride recovery has been tracked to differentiate between PFAS destruction and other potential removal mechanisms. Experiments have been conducted at several different scales and reactor/lamp configurations including batch-scale, 35-milliliter (mL) borosilicate mini-column reactors, a 500-mL flow-through reactor containing UV lamps encased in quartz sleeves, a 3.8-gallon per minute recirculation reactor utilizing 85-watt UV lamps, and a modified recirculation reactor. The field demonstration will provide a basis for assessing field performance including treatment efficiency and kinetics of PFAS mixtures, treatment duration, energy requirements, effect of co-occurring chemicals and water quality parameters. It will also assess ease of operation, media fouling, costs, and other operation and maintenance considerations. This study will identify factors affecting technology cost and performance when treating various concentrated PFAS liquid wastes.

Destructive PFAS treatment technologies may offer several advantages when used in combination with technologies that sequester PFAS. Spent granular activated carbon, ion exchange resin, membrane reject streams, and other concentrated wastes are typically shipped off-site for incineration or placed in a hazardous waste landfill. UV/SGM treatment has a greater potential to reduce toxicity and volume, lower cost, improve long-term effectiveness and permanence, and foster regulatory and community acceptance. UV/SGM technology has the potential to achieve PFAS destruction at room temperature and pressure, thereby keeping energy requirements low. UV/SGM has already been demonstrated to destroy the complex mixtures of PFAS that are typically found in the environment. (Anticipated Project Completion - 2026)