New insights into the occurrence and fate of per- and polyfluoralkyl substances in textile dyeing wastewater along different treatment processes to receiving rivers

Abstract

Per- and polyfluoroalkyl substances (PFASs) are widely used in the textile dyeing industry resulting in textile dyeing wastewater being discharged as a significant source of PFASs in aquatic environments. However, very limited information is available on the occurrence and fate of PFASs among different textile dyeing wastewater treatment processes. This study investigated thirteen targeted PFASs across 15 textile dyeing enterprises (abbreviated as A1–A15), 4 wastewater treatment plants (abbreviated as WWTPs 1–4), and 5 receiving surface waters. Specifically, WWTP-1 and WWTP-2 were equipped with an anaerobic–anoxic–oxic (A²/O) process, while WWTP-3 and WWTP-4 with an anoxic–oxic (A/O) process. Four WWTPs respectively treated raw textile dyeing wastewaters from A1–A6, A7–A11, A12 and A13, and A14 and A15 for standard emission. Results indicated that the total concentration of 13 PFASs (Σ₁₃PFASs) ranged from 23.80 to 1867.33 ng L⁻¹ in raw textile dyeing wastewaters, with short-chain perfluorocarboxylic acids (PFCAs) accounting for 60%. The comparison of two different treatment processes demonstrated that the A²/O process was more effective for the removal of long-chain PFCAs, which was attributed to the transformation of long-chain PFASs by the anaerobic environment. Moreover, the Σ₁₃PFASs in five surface waters were 235.46 to 2787.03 ng L⁻¹, and the correlation analysis revealed significant similarity of PFAS composition among surface waters with A3, A11, and WWTP-1 effluent (p < 0.01). Overall, this study comprehensively investigated the PFAS occurrence and fate in textile dyeing wastewater and receiving rivers along associated wastewater treatment processes, thus providing new insights into different textile dyeing wastewater treatment processes for PFAS dynamic alteration.