Occurrence, Fate, and Removal of Per- and Polyfluoroalkyl Substances (PFAS) in Small- and Large-Scale Municipal Wastewater Treatment Facilities in the United States

Juhee Kim; Xiaoyue Xin; Gary L Hawkins; Qingguo Huang; Ching-Hua Huang

doi:10.1021/acsestwater.4c00541

Occurrence, Fate, and Removal of Per- and Polyfluoroalkyl Substances (PFAS) in Small- and Large-Scale Municipal Wastewater Treatment Facilities in the United States

ACS ES T Water. 2024 Nov 15;4(12):5428-5436. doi: 10.1021/acsestwater.4c00541. eCollection 2024 Dec 13.

Authors

Juhee Kim^{1

2}, Xiaoyue Xin¹, Gary L Hawkins³, Qingguo Huang⁴, Ching-Hua Huang¹

Affiliations

¹ School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
² Department of Civil, Environmental and Construction Engineering, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States.
³ Department of Crop and Soil Sciences, University of Georgia, Athens, Georgia 30223, United States.
⁴ Department of Crop and Soil Sciences, University of Georgia, Griffin, Georgia 30223, United States.

Abstract

Wastewater treatment plants (WWTPs) could be conduits of polyfluoroalkyl substances (PFAS) contaminants in the environment. This study investigated the fate of 40 PFAS compounds across nine municipal WWTPs with varying treatment capacity and processes. High concentrations of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) were detected in wastewater, with the ratio of their total concentrations (∑PFCAs/∑PFSAs) always greater than one. Transformation of precursors by activated sludge processes significantly increased the concentrations of short-chain PFCAs (e.g., perfluoropentanoic acid (PFPeA) and perfluorohexanoic acid (PFHxA)), while further advanced treatment processes offered minimal removal of perfluoroalkyl acids. Treatment capacity and PFAS removal efficiency showed no apparent correlation. The maximum possible PFAS loads discharged from WWTPs were 340-9645 g·year^-1, similar to those entering the WWTPs. Among six regulated PFAS compounds, detection frequency was 100% for five (perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorononanoic acid (PFNA), perfluorobutanesulfonic acid (PFBS), and perfluorohexanesulfonic acid (PFHxS)) and 67% for hexafluoropropylene oxide dimer acid (HFPO-DA) (Gen-X). Concentrations of PFOA and PFOS in WWTP discharges consistently exceeded 4 ng·L^-1. The hazard index (HI) for mixtures containing two or more of the four PFAS (PFNA, PFBS, PFHxS, and HFPO-DA) ranged from 0.2 to 6.1. These findings indicate that wastewater discharges may pose a risk, emphasizing the need for enhanced PFAS removal strategies in wastewater treatment processes.