Science Inventory

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

Citation:

Liu, Y., N. Robey, J. Bowden, T. Tolaymat, B. da Silva, H. Solo-Gabriele, AND T. Townsend. From Waste Collection Vehicles to Landfills: Indication of Per- and Polyfluoroalkyl Substance (PFAS) Transformation. Environmental Science & Technology Letters. American Chemical Society, Washington, DC, 8(1):66-72, (2020). https://doi.org/10.1021/acs.estlett.0c00819

Impact/Purpose:

In this study, a diverse suite of PFAS were detected in the leachate of residential and commercial waste collection vehicles prior to waste disposal in a landfill. These results confirm that PFAS historically measured in landfill leachates are not necessarily derived from special waste (e.g., remediation waste, biosolids, industrial waste), suggesting that even the basic components of our waste streams produced from houses and businesses are significant contributors to PFAS loading at municipal landfill sites. It should be noted that while a direct comparison of concentrations between landfill and vehicle leachates is problematic, due to different exposure conditions (i.e., liquid to solid ratio, contact time) and the high variability of leachate samples obtained from waste collection vehicles, the relative diversity of the compounds measured in these two leachate types is noteworthy and warrants further attention. The majority of PFAS present in vehicle leachate were precursor compounds whereas those detected in landfill leachate were mainly comprised of terminal PFAS. This suggests that, to some degree, PFAA-precursors were being transformed to PFAA throughout the “landfilling” process from transport through landfill degradation. The substantially higher contributions (by concentration) of select PFAS, like PFHxA, in landfill leachate versus vehicle leachate, also supports the theory of transformation of precursors to PFHxA, and likely other PFAA compounds, within the landfill environment. The sources of PFAS in MSW should be further scrutinized to identify the major waste contributors of PFAS that are being transferred to landfills on a daily basis to better address mitigation actions.

Description:

Wastes produced daily from households and businesses contain a diverse and significant amount of per- and polyfluoroalkyl substances (PFAS) and these compounds may be transformed during transport and decomposition within landfills. Fresh vehicle leachates, from residential and commercial waste collection vehicles at a transfer station, were measured for 51 PFAS species. Results were compared to PFAS levels obtained from aged landfill leachate at the disposal facility. A variety of PFAS chemicals were detected in vehicle leachates from both residential and commercial sources, with a predominance of perfluoroalkyl acid (PFAA) precursors (66% and 75% in commercial and residential waste vehicle leachate, respectively) with 6:2 diPAP, a phosphate diester that is known to present in food packaging materials and other consumer products. Overall, landfill leachates had higher levels of measured PFAS and were dominated by terminal species (87%), when compared to vehicle leachate. These results suggest that there is likely precursor transformation to terminal PFAS over the course of the waste degradation process starting with waste transport.