Science Inventory

Municipal solid waste incineration (MSWI) ash co-disposal: Influence on per- and polyfluoroalkyl substances (PFAS) concentration in landfill leachate

Citation:

Liu, Y., P. Mendoza-Perilla, K. Clavier, T. Tolaymat, J. Bowden, H. Solo-Gabriele, AND T. Townsend. Municipal solid waste incineration (MSWI) ash co-disposal: Influence on per- and polyfluoroalkyl substances (PFAS) concentration in landfill leachate. WASTE MANAGEMENT. Elsevier Science Ltd, New York, NY, 144:49-56, (2022). https://doi.org/10.1016/j.wasman.2022.03.009

Impact/Purpose:

Description:

To explore the contribution of municipal solid waste incineration (MSWI) ash to PFAS in landfills, leachate was collected from four landfills disposing of municipal solid waste incineration (MSWI) ash, either as a sole waste stream or co-disposed with other unburned materials (sewage sludge and MSW screenings). These samples were analyzed for 26 per- and polyfluoroalkyl substances (PFAS). Greater ash content was associated with lower measured landfill leachate PFAS concentrations: pure ash monofill had the lowest PFAS in its landfill leachate (290 ng L-1) while the landfill dominated by unburned wastes had the highest PFAS in its leachate (11,000 ng L-1). In addition, EPA 1316 leaching test was conducted on ash and unburned materials to assess the leachable PFAS in the individual components (leachate produced are referred to as sample leachates). Average leachable PFAS in ash sample leachate (310 ng L-1) was comparable to landfill leachate from pure ash monofill, but was 10 and 24 times lower than those observed in sewage sludge sample leachate (3,200 ng L-1) and MSW sreenings sample leachate (7,500 ng L-1), respectively. A mass-weighted calculation indicated that other unburned PFAS-rich wastes contribute a disproportionately greater PFAS content to the landfill leachate, with a small fraction of unburned wastes in the landfill greatly elevates PFAS in landfill leachate. We hypothesize that the bulk ash matrix has low permeability and thus leachate generated in co-disposal scenarios preferentially flows through the PFAS-rich unburned materials prior to collection. Given the disproportionate contribution of PFAS from the unburned components, a true monofill scenario will produce leachates with lower PFAS levels.