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

By Shubhashini Oza, Hui Li, Qingguo Huang, John W Norton, Lloyd J Winchell, Martha J M Wells, Thomas Nangle, Natalia Perez, Dan DeLaughter, Jan M Hauser, Malcolm Taylor, Zonetta E English, Mike Melnyk, Phuong Truong, and Katherine Y Bell
Water Environ Res.
February 9, 2025
DOI: 10.1002/wer.70039

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. PRACTITIONER POINTS: Among the 40 target PFAS, four were above reporting limit in the pre-stabilized sludge and nine in the post-stabilized product. Incineration ash (post-stabilized product) samples did not have any reportable PFAS. 5:3 FTCA and PFOS were the two frequently observed compounds; concentrations were higher in the post-stabilized product compared to the pre-stabilized sludge. PFPeA and PFHxA were the only two short chain perfluoroalkyl carboxylic acids reported. PFOA was reported in only one of the 54 samples evaluated.

View on PubMed