Pilot-Scale Demonstration of Conductive Thermal Desorption Coupled with On-Site Vapor Reburn for PFAS Mineralization

PFAS-contaminated soils remain challenging to remediate because many approaches remove but do not destroy PFAS. This study presents an integrated thermal process combining ex-situ Thermal Desorption Remediation (TDR) with on-site high-temperature oxidation of desorbed PFAS vapors, enabling simultaneous soil treatment and on-site PFAS destruction. Two pilot-scale demonstrations treated 28-ton batches of contaminated soil in Thermal Conductive Heating (TCH)-equipped containers. Six steel conduction tubes heated by gas burners achieved uniform soil temperatures of 350 °C within 14 days. Initial PFAS concentrations (85–210 µg/kg dry weight, Σ22 PFAS, mainly PFOS) decreased to 0.11 µg/kg dry weight after treatment, corresponding to a mass removal efficiency exceeding 99.8%. Desorbed vapors were directly injected into the burner flames of the conductive heating tubes, where they were exposed to a Reburn® oxidation zone above 1400 °C under oxygen- and steam-rich conditions, promoting extensive PFAS destruction. Stack monitoring following U.S. EPA OTM-45 and OTM-50 methods detected volatile fluorinated compounds and PFBA before reburn, whereas no PFAS compounds were detected after treatment (<0.0001 µg/Nm³ for PFOS/PFOA), indicating effective destruction under the monitored conditions. The process consumed approximately 980 kWh per ton of soil, mainly due to sensible heat losses in exhaust gases; heat recovery integration is expected to reduce energy demand below 350 kWh/t. Ambient air monitoring showed no measurable increase in PFAS concentrations compared with baseline levels. These results demonstrate the technological feasibility, environmental performance, and scale-up potential of the proposed PFAS remediation process.