Per- and polyfluoroalkyl substances in untreated and treated sludge/biosolids from 27 water resource recovery facilities across the United States and Canada

Per- and polyfluoroalkyl substances (PFAS) are being studied in all environmental matrices because of their ubiquitous presence and adverse human health impacts. This study conducted a surveillance of 27 water resource recovery facilities throughout the United States and Canada to screen the range of PFAS concentrations in pre-stabilized sludge and post-stabilized product. Among the 27 water resource recovery facilities, 82% use anaerobic digestion and the rest use chemical stabilization and/or incineration for sludge stabilization. Forty PFAS compounds were evaluated by US Environmental Protection Agency Method SW846/537.1, and four and nine compounds were reported in the pre-stabilized sludge and post-stabilized product, respectively. Concentrations of reported compounds in pre-stabilized sludge and post-stabilized product varied from 5 to 33 ng/g dry basis and 2 to 220 ng/g dry basis, respectively. 3-Perfluoropentylpropanoic acid (5:3 FTCA) and perfluorooctanesulfonic acid (PFOS) were the most frequently observed compounds, and PFAS concentrations in the post-stabilized products were generally higher than the corresponding pre-stabilized sludge.