Smouldering Combustion Treatment of Soils and Granular Activated Carbon Contaminated with Per- and Polyfluoroalkyl Substances

Abstract

Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants, ubiquitous in the environment, and are challenging to remediate. Self-sustaining Treatment for Active Remediation (STAR) destroys organic contaminants embedded in porous media using smouldering combustion. Self-sustaining smouldering conditions allow the reaction to propagate through the contaminated media without external energy. This study explored STAR as a remediation option for PFAS-impacted granular activated carbon (GAC) and PFAS-contaminated soil. Three smouldering mixtures were used (i) PFAS-spiked GAC and sand, (ii) PFAS-spiked soil and GAC, (iii) PFAS-contaminated field site soil and GAC. Smouldering temperatures were greater than 900˚C, destroying the GAC. Post-treatment PFAS concentrations of the sand, soil, and ash were near or below detection limits (0.5 μg/kg). Analysis of emissions demonstrated hydrogen fluoride and shorter-chain PFAS were produced suggesting PFAS had been mineralized and altered during smouldering. Results suggest STAR is an effective remediation technique for PFAS-impacted soils and PFAS-saturated GAC

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