PFAS release from wastewater residuals as a function of composition and production practices

Per- and polyfluoroalkyl substances (PFAS) are a class of highly persistent contaminants that have been linked to human health effects at low exposure concentrations. Public concerns exist that land-application of biosolids may result in the release of PFAS into terrestrial and aquatic ecosystems. The relative importance of inorganic constituents such as Fe and Al, which are known to impact PFAS retention/release behavior in soils, on PFAS release from wastewater residuals (WWRs, i.e., biosolids and sewage sludges) is not well understood. Here, we examine native concentrations and WWR-water partition coefficients of a range of PFAS in the context of WWRs characteristics including oxalate-extractable Fe and Al, organic matter (OM), dissolved organic carbon, and total protein content. Total PFAS concentrations, which included perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, fluorotelomer sulfonates and some sulfonamides, ranged from similar to 480 to 3500 mu g PFAS kg(-1) dry weight. PFAS WWR-water partition coefficients ranged from similar to 10 to 20,000 L kg(-1), consistent with the literature. PFAS partitioning was significantly correlated to oxalate extractable Al and Fe as well as bulk OM and protein content. These results have important implications for wastewater treatment facilities that recycle Al-and Fe-based drinking water treatment residuals in terms of both PFAS retention and loading.

Automated summary

Per- and polyfluoroalkyl substances (PFAS) are persistent contaminants that may pose health risks at low doses. Concerns exist regarding the release of PFAS into the environment through land application of biosolids. The relationship between inorganic constituents (such as Fe and Al) and PFAS release from wastewater residuals is not well understood.