Characterizing PFAS concentrations in drinking water treatment residuals

Abstract

While drinking water treatment plants (DWTPs) are not considered a source of per- and polyfluoroalkyl substances (PFAS), PFAS concentrate in treatment residuals relative to their source water concentrations. Regulatory actions considered for PFAS-impacted residuals could affect the cost and viability of conventional residual management practices. This study estimated the annual quantity of residuals generated in the United States and presents a framework for understanding how PFAS may concentrate in these residual streams. Findings of this work indicate that PFAS may substantially impact DWTP residuals management, especially coagulation and softening solids, at concentration factors greater than 100 and spent adsorbents at PFAS concentration factors greater than 10,000. If potential regulatory actions were to apply to coagulation and softening residuals, those regulations must consider impacts on disposal of more than 420,000,000 wet tons of at-risk DWTP residuals which are generated annually.