A ‘Concentrate-&-Destroy’ technology for enhanced removal and destruction of per- and polyfluoroalkyl substances in municipal landfill leachate

Abstract

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in landfill leachate due to their widespread applications in various industrial and consumer products. Yet, there has been no cost-effective technology available for treating PFAS in leachate because of the intrinsic persistency of PFAS and the high matrix strength of landfill leachate. We tested a two-step ‘Concentrate-&-Destroy’ technology for treating over 14 PFAS from a model landfill leachate through bench- and pilot-scale experiments. The technology was based on an adsorptive photocatalyst (Fe/TNTs@AC), which was able to selectively adsorb PFAS despite the strong matrix effect of the leachate. Moreover, the pre-concentrated PFAS on Fe/TNTs@AC were effectively degraded under UV, which also regenerates the material. The presence of 0.5 M H2O2 during the photocatalytic degradation enhanced the solid-phase destruction of the PFAS. Fresh Fe/TNTs@AC at a dosage of 10 g/L removed >95% of 13 PFAS from the leachate, 86% after first regeneration, and 74% when reused three times. Fe/TNTs@AC was less effective for PFBA and PFPeA partially due to the transformation of precursors and/or longer-chain homologues into these short-chain PFAS. Pilot-scale tests preliminarily confirmed the bench-scale results. Despite the strong interference from additional suspended solids, Fe/TNTs@AC removed >92% of 18 PFAS in 8 h under the field conditions, and when the PFAS-laden solids were subjected to the UV-H2O2 system, ~84% of 16 PFAS in the solid phase were degraded. The ‘Concentrate-&-Destroy’ strategy appears promising for more cost-effective removal and degradation of PFAS in landfill leachate or PFAS-laden high-strength wastewaters.