Distribution of per and polyfluoroalkyl substances (PFAS) and metals in United States municipal solid waste...

Fly ash formed during municipal solid waste incineration (MSWI) contains constituents of concern including per- and polyfluoroalkyl substances (PFAS) and trace metals. However, PFAS occurrence in distinct fly ash fractions and the relationship between PFAS and metals in such systems is not well understood. This study investigated the occurrence and distribution of PFAS and trace metals (As, Ba, Cd, Cr, Pb, Sb, Se) in distinct MSWI fly ash fractions and the influence of physical-chemical characteristics (i.e. pH, particle size distribution, loss-on-ignition). In characterizing two, full-scale MSW combustors and their generated fly ashes, we demonstrated that PFAS and volatile metals (As, Cd, Pb, Sb) exhibit similar distributions, with concentrations in distinct FA fractions ranging from 0.007 - 0.830 ng/g and 1,080 - 3,640 mg/kg, respectively. PFAS and volatile metals concentrations exhibited positive correlations with loss-on-ignition and negative correlations with particle size, suggesting combustion efficiency, organic carbon content, and surface area to be primary drivers. A positive correlation exists between PFAS and volatile metals concentrations (r_s > 0.7), suggesting they could be managed in concert. The highest constituent concentrations were observed in fly ash captured within the baghouse of both combustors, pointing to an opportunity for optimized management of fly ash through targeted segregation of baghouse residuals. This data provides the first comprehensive assessment of PFAS and metals in distinct FA fractions from US MSWIs and identified the drivers for PFAS and trace metals partitioning to inform safe and optimal management.