Municipal landfills are part of the next generation of hazardous waste sites. The leachate coming from landfills is a highly complex matrix containing a myriad of compounds of environmental concern, including poly and perfluoroalkyl substances (PFASs). To quantify the influence on PFAS concentration and composition of (1) abiotic leaching and (2) biodegradation their release was studied in laboratory scale bioreactors and microcosms. Said reactors contain shredded municipal waste and circulating pH neutralized leachate under carefully controlled methanogenic conditions that mimic landfill biodegradation. The background laboratory contribution to overall PFAS levels was found to be below 10 ng/L by mimicking reactor operation with reagent water and synthetic model leachates representing the extreme acid and methane phases of landfill degradation. Streptomycin and Dowicil QK-20 (2,2-dibromo-3-nitrilopropionamide) were used to inhibit microbial growth in abiotic reactors because of the lesser degree of PFAS signal suppression in the analytical method at effective concentrations. Anaerobic decomposition in the reactors is characterized by methane production rate, leachate pH, and chemical oxygen demand (COD). To identify product specific PFAS contributions, reactors are assembled with textiles and carpets sorted from whole refuse. Individual microcosms were also analyzed for individual paper products ranging from picnic ware and magazines to dog food bags. Over the first month of operation, PFAS concentrations in biologically active reactor leachate reached a maximum with in the first 10 days. The observed PFASs included well known constituents, as well as new PFASs, like fluorotelomer phosphates, as of yet unobserved in leachate.

Biodegradational influence on poly and perfluoroalkyl substance (PFAS) release into landfill leachate

246th National Meeting (2013)

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