Destruction process that holds water above its critical point (374 degrees Celsius, 22.1 MPa) so that organics, oxygen, and water form a single phase and oxidize rapidly. Demonstrated to mineralize PFAS to fluoride, CO2, and water, but currently limited to liquid and slurry feeds.
Supercritical water oxidation operates above the critical point of water, where the fluid loses its liquid-gas distinction and dissolves organics and oxygen in a single phase. Reaction times are seconds, and destruction efficiencies above 99.99 percent have been reported for PFOA, PFOS, and AFFF concentrates by vendors including 374Water, General Atomics, and Battelle.
SCWO is a strong candidate for PFAS-laden liquids: spent activated carbon regenerant, ion exchange brine, landfill leachate, and AFFF stockpiles. Throughput is currently measured in tens of gallons per minute per unit, and energy demand is offset partially by the exothermic oxidation of co-contaminant organics.
Limitations are material: salt precipitation and chloride-driven corrosion of reactor walls have constrained scale-up, and SCWO does not handle bulk solids or contaminated soil. For soil-bound PFAS the prevailing destruction route remains high-temperature thermal treatment with secondary oxidation of off-gas.
Also known as: SCWO, supercritical water oxidation.
PFAS (Per- and Polyfluoroalkyl Substances): treatment approach
A family of thousands of synthetic fluorinated organics — including PFOA, PFOS, GenX, PFHxS, and AFFF constituents — defined by C-F bonds that resist conventional treatment and require destruction technologies to close a site.
An ex-situ soil treatment process that heats contaminated soil to volatilize and separate organic contaminants from the soil matrix, after which the liberated vapors are captured and treated, usually in a high-temperature oxidizer.
A thermal desorption configuration where the heat source contacts the soil directly inside the rotary unit, delivering high heat-transfer efficiency and supporting higher treatment temperatures.
A thermal desorption configuration where heat is conducted through the wall of the treatment vessel without combustion gases contacting the soil, producing a concentrated, lower-volume vapor stream suitable for condensation and recovery.
Treatment that heats contaminated soil and groundwater in place, typically with electrical resistance, thermal conduction, or steam injection, to volatilize and recover contaminants without excavation. Used where excavation is impractical or where the contaminant zone sits beneath active infrastructure.