A Critical Review and Meta-Analysis of the Occurrence and Fate of Per- and Polyfluoroalkyl Substances in Global Wastewater Treatment Plants

This critical review presents a comprehensive meta-analysis
on
the global occurrence and fate of per- and polyfluoroalkyl substances
(PFAS) in wastewater treatment plants (WWTPs). We reviewed over 86
peer-reviewed studies and extracted PFAS concentration data from 717
WWTPs worldwide, encompassing influent, effluent, and residual streams
across all treatment stages. A publicly accessible, open-source ArcGIS
map was developed to display key information from each study, including
geographic location, sampling year, treatment train details, and measured
PFAS concentrations. Descriptive and inferential statistical analyses
were used to assess occurrence patterns, treatment performance, and
transformation trends. Results show strong regional bias in PFAS monitoring,
with data concentrated in the U.S., China, and Europe. Despite differences
in treatment configuration, conventional WWTPs were generally ineffective
at removing PFAS. In WWTPs with secondary treatment, PFOA and PFOS
were the most frequently reported and abundant PFAS (>10 ng/L)
in
aqueous streams, while residuals were dominated by PFOA, PFOS, PFNA,
and EtFOSAA. Tertiary systems showed several PFAS had aqueous median
concentrations exceeding 10 ng/L. Industrial sources contributed significantly
higher influent concentrations than municipal or combined systems.
Paired influent and effluent data sets revealed an increase in terminal
perfluoroalkyl acids and a decrease in precursors across treatment.
Despite these trends, data on precursors, short-chain PFAS, and the
impact of specific treatment processes and operating conditions remains
limited. This review underscores the critical need for standardized
sampling approaches across treatment trains and highlights opportunities
to improve PFAS mitigation through targeted monitoring and technology
development.