From Waste Collection Vehicles to Landfills: Indication of Per- and Polyfluoroalkyl Substance (PFAS) Transformation

Municipal solid waste contain diverse and significant amounts of per- and polyfluoroalkyl substances (PFAS), and these compounds may transform throughout the landfilling process from transport through landfill degradation. Fresh vehicle leachates, from commercial and residential waste collection vehicles at a transfer station, were measured for 51 PFAS. Results were compared to PFAS levels obtained from aged landfill leachate at the disposal facility. The landfill leachate was dominated by perfluoroalkyl acids (PFAAs, including perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs); 86% of the total PFAS, by median mass concentration), while the majority of PFAS present in commercial and residential waste vehicle leachate were PFAA-precursors (70% and 56% of the total PFAS, by median mass concentration, respectively), suggesting precursor transformation to PFAAs during the course of landfill disposal. In addition, several PFAS, which are not routinely monitored-perfluoropropane sulfonic acid (PFPrS), 8-chloro-perfluoro-1-octane sulfonic acid (8CI-PFOS), chlorinated polyfluoroether sulfonic acids (6:2, 8:2 CI-PFESAs), sodium dodecafluoro-3H-4,8-dioxanonanoate (NaDONA), and perfluoro-4-ethylcyclohexanesulfonate (PFECHS)-were detected. Potential degradation pathways were proposed based on published studies: transformation of polyfluoroalkyl phosphate diester (diPAPs) and fluorotelomer sulfonic acids (FTS) to form PFCAs via formation of intermediate products such as fluorotelomer carboxylic acids (FTCAs).

Automated summary

Municipal solid waste contains significant amounts of PFAS, which may transform during landfilling. Landfill leachate was found to be dominated by PFAAs, while commercial and residential vehicle leachate contained mostly PFAA-precursors, indicating precursor transformation during landfill disposal. Additional PFAS not routinely monitored were detected, with proposed degradation pathways involving diPAPs and FTS transformation into PFCAs via FTCAs.