This project seeks to evaluate through direct measurement the ability of high temperature incineration to destroy per- and polyfluoroalkyl substances (PFAS). More test data are needed to confirm the ability of incineration to destroy PFAS at high efficiency. The research will focus on a mass balance of PFAS incineration within a certified/permitted hazardous waste incinerator. Previous testing at the facility showed >99.9999% destruction of principal PFAS, and this additional testing is planned to confirm the high destruction/removal efficiencies and to investigate products of incomplete destruction (PIDs) and hopefully demonstrate minimal PFAS emissions to air. More specific goals will be to (i) determine the degree of principal PFAS destruction/removal; (ii) identify PIDs and the amounts liberated during PFAS decomposition; and (iii) evaluate the likely cost-effectiveness of incineration relative to other PFAS destruction technologies.

The study is a collaborative effort between the facility owner, the U.S. Environmental Protection Agency (EPA), and the U.S. Department of Defense. A mass balance approach will be applied to targeted PFAS to estimate their fate and destruction efficiencies in a high temperature combustion process designed to burn/destroy organic hazardous wastes. Testing will be conducted in a hazardous waste combustion facility that provides long combustion gas residence times at high temperatures. PFAS will be measured in and out of the combustion process, and samples of waste byproducts from air pollution control equipment will be analyzed for PFAS mass balances. Aqueous film-forming foam (AFFF) will be injected into the combustion device at sufficient PFAS loads to be measurable in stack emissions assuming limited destruction. Waste feeds will also be spiked with principal PFAS and hexafluoroethane (C2F6). Stack emissions will be measured using the EPA’s Other Test Methods (OTMs) 45 and 50, designed respectively for principal (polar) PFAS and non-polar PID PFAS, and “OTM-55” (U.S. EPA SW-846 Method 0010 combined with SW-846 Methods 3542/8270) for semi-volatile non-polar PFAS. Stack exhaust will also be analyzed by fourier-transform infrared (FTIR) spectroscopy to look for short-chain PFAS such as carbon tetrafluoride and C2F6 that may be present as residual products of incomplete combustion. Process samples (e.g., ash and scrubber residue) will be collected during the stack test period and analyzed for PFAS to check for PFAS transfer to these materials. Destruction efficiencies will be estimated from the differences between the amount of PFAS introduced to the combustion process less the amounts measurable in combustion effluents and process streams. The effectiveness and cost of high temperature incineration will be compared with other data and information on other treatment methods as available.

Viable disposal options are needed for managing PFAS-containing wastes and materials that are preferably destructive in nature (and not simply sequestering). These waste streams include impacted soil and drill cuttings, spent granular activated carbon, spent resin, filtered sludge and filter bags, piping used for AFFF, and concrete. Stack testing will evaluate PFAS destruction to inform on the degree to which incineration destroys PFAS, and hence its reliability as a safe and effective PFAS disposal option. If incineration of PFAS waste is shown to destroy PFAS at high efficiency, this would provide a method to permanently destroy PFAS-containing materials releasing any future liability. (Anticipated Project Completion - 2025)