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Remediation of PFAS-Contaminated Soil and Granular Activated Carbon by Smouldering Combustion.

This study explored smouldering combustion for remediating PFAS-impacted granular activated carbon (GAC) and PFAS-contaminated soil. GAC, both fresh and PFAS-loaded, was employed as the supplemental fuel supporting smouldering in mixtures with clean sand (≈175 mg PFAS/kg), with PFAS-spiked, laboratory-constructed soil (≈4 mg PFAS/kg), and with a PFAS-impacted field soil (≈0.2 mg PFAS/kg). The fate of PFAS and fluorine was quantified with soil and emissions analyses, including targeted and non-targeted PFAS as well as hydrogen fluoride and total organic fluorine. Results demonstrated that exceeding 35 g GAC/kg soil resulted in self-sustained smouldering with temperatures exceeding 900˚C. Post-treatment PFAS concentrations of the treated soil were near (2 experiments) or below (7 experiments) detection limits (0.0005 mg/kg). 44% of the initial PFAS on GAC underwent full destruction, compared to 16% of the PFAS on soil. Less than 1% of the initial PFAS contamination on GAC or soil was emitted as PFAS compounds in the quantifiable analytical suite. Results suggest that the rest were emitted as altered, shorter-chain PFAS and volatile fluorinated compounds, which were scrubbed effectively with GAC. Total organic fluorine analysis proved useful for PFAS-loaded GAC in sand, however analyzing soils suffered from interference from non-PFAS compounds. Overall, this study demonstrated that smouldering has significant potential as an effective remediation technique for PFAS-impacted soils and PFAS-laden GAC.