Distribution and variability of per- and polyfluoroalkyl substances (PFASs) across three categories of wastewater treatment plants in Kaohsiung, the industrial hub of Taiwan

Abstract

Paired surface wastewater samples from seven wastewater treatment plants (WWTPs) in Kaohsiung, Taiwan, were analyzed to quantify environmental PFAS loadings. Seventeen per- and poly-fluoroalkyl substances (PFASs) were analyzed, whereby WWTPs 1–4, treating domestic discharges, exhibited relatively low concentrations of 10.5–46.8 ng L⁻¹. WWTP 5, handling mixed domestic and light industrial wastewater, had moderate levels of 45.7–102.3 ng L⁻¹. WWTPs 6 and 7, which process heavy industrial discharges, recorded the highest PFAS concentrations of up to 2790 ng L⁻¹ and 4290 ng L⁻¹, respectively. The dominant PFAS compounds varied by facility: perfluoropentanoic acid (PFPeA) and 6:2 fluorotelomer sulfonate (6:2 FTS) in WWTPs 1–4, 6:2 FTS and perfluorooctanesulfonic acid (PFOS) in WWTPs 5, 6, and 7. Principal Component Analysis (PCA) confirmed that reverse osmosis (RO) effectively reduced PFAS concentrations, while conventional treatment processes lacked significant degradation capability. Three WWTPs (5–7) in Kaohsiung's heavily industrialized southern region had effluent PFAS levels exceeding the EPA lifetime health advisory limit of 70.0 ng L⁻¹. These findings highlight the urgent need for advanced treatment technologies and provide essential data to support Taiwan EPA's PFAS management regulations in WWTPs.