Hydrothermal Treatment of PFAS-Contaminated Groundwater

Per- and polyfluoroalkyl substances (PFAS) have been used extensively since the 1940s due to their chemical stability and unique thermophysical properties. Those same properties make PFAS extremely recalcitrant environmental pollutants and bioaccumulative toxins. The most significant PFAS issues are a direct result of the discharge of aqueous film-forming foam (AFFF), both for firefighter training activities and suppression of petroleum fires. For decades, firefighters were told that AFFF was �biodegradable�, and instructed to wash the foam directly into the soil after discharge. In response to the PFAS crisis, several states have issued regulatory standards for PFAS, and the U.S. EPA has established health advisory levels for PFOA and PFOS, two of the most prevalent and persistent PFAS compounds. While several technologies exist for filtration of PFAS from water supplies, the end-of-life destruction of PFAS remains a challenge. Project managers at environmental engineering firms have a strong need for effective, affordable, and field-deployable PFAS destruction systems, especially for contaminated liquids. Aquagga has robustly demonstrated the efficacy of the hydrothermal alkaline treatment (HALT) process for destroying >99.99% of PFAS in a wide range of liquid matrices. Aquagga�s HALT system effectively destroys all PFAS (including short- and long-chain compounds) with low energy consumption and scalable processing parameters. Total PFAS destruction via HALT ensures compliance with emerging regulations, and protection against future liability, unlike the current industry practices of incineration or landfilling. Additionally, HALT is well-suited for on-site deployment for the destruction of stockpiled wastes and remediation byproducts. In the Phase I project, Aquagga demonstrated >99.9% destruction of total PFAS in a contaminated liquid sample from a fire training pit, with total starting PFAS levels of ~2 ppm. Destruction tests were performed in a continuous HALT reactor, which showed faster destruction rates than similar batch reactor systems. Additionally, a pilot-scale HALT system was fully designed, and viable pilot sites were identified. In this Phase II project, a pilot-scale HALT system will be fabricated, and pilot tested for PFAS destruction performance. Metrics of performance will be quantified, including PFAS destruction efficacy, energy usage, throughputs, operational costs, and capital costs. Pilot testing will de-risk the HALT technology for use at PFAS-impacted sites and will demonstrate the ease of integration with existing remediation practices. By the end of the Phase II project Aquagga�s HALT system will be ready to transition towards contracted commercial deployments at active PFAS remediation sites.