Sudhakar Viswanathan

Supercritical Water Oxidation for Permanent Destruction of PFAS in Stockpiled AFFF

Sudhakar Viswanathan, Vice President, 374Water

The use of firefighting foams for training, calibration activities, and emergency response is essential, but increased attention on the unintentional release of per- and polyfluoroalkyl substances (PFAS) are changing which types of foams are used. With numerous bans on the discharge of foam into the ground, storm drain, or sewer systems and the transition away from aqueous film-forming foams (AFFF) there will be increasing volumes of stockpiled AFFF. Safely storing the stockpiles on site is only a short-term solution as, amongst other factors, upcoming RCRA definitions of hazardous waste that may include PFAS jeopardize this practice. These warrant planning for the disposal of AFFF stockpiles.  Current techniques included in EPA’s 2024 Version 2 Interim Guidance document are thermal treatment, landfills, and underground injection. The guidance also presents EPA’s PFAS Innovative Treatment Team (PITT) evaluations of emerging technologies including electrochemical oxidation, mechanochemical degradation, pyrolysis, gasification, and supercritical water oxidation (SCWO).  This talk will equip the audience with the data and considerations needed to start planning for safe cost-effective disposal, even in the face of new regulations. Firstly, the concept of “concentrate and destroy” will be used to categorize interim and emerging technologies. A brief overview of how each technology works to concentrate or destroy hazardous compounds in AFFF will be given to facilitate selection of methods capable of achieving the desired treatment efficiency. The focus will then shift to a comparison of the technology readiness level, cost/funding mechanisms, and potential benefits of the emerging technologies including electrochemical oxidation, mechanochemical degradation, pyrolysis, gasification, and supercritical water oxidation (SCWO). The main takeaway of the talk is to emphasize the importance of keeping costs down, ensuring compliance, and advancing the industry toward sustainable waste management practices. 

Sudhakar (Sunny) Viswanathan is Vice President at 374Water, a global cleantech, social impact company based in Durham, NC. He has a bachelor’s and a master’s degree in environmental engineering, and is a Syracuse University alumnus with nearly 25 years of industry experience including leadership positions at Suez and Veolia. Sunny has authored over 35 technical papers and currently spearheads the commercialization and business development of the Supercritical Water Oxidation technology.