Occurrence and Treatment Technologies of Per- and Polyfluoroalkyl Substances in Electroplating Wastewater: A Review.

Per- and polyfluoroalkyl substances (PFASs) are a class of persistent pollutants, and China's electroplating industry is a major source of their emissions. This paper systematically reviews the sources, occurrence characteristics, and treatment technologies of PFASs in electroplating wastewater. The chrome plating process is the primary source of PFASs, with concentrations of perfluorooctane sulfonic acid (PFOS), 6:2 fluorotelomer sulfonate (6:2 FTS), and 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFESA, F-53B) in some chromium mist suppressants reaching up to 985, 735, and 875 g/kg, respectively. Monitoring data from 15 electroplating parks and 97 enterprises revealed that 29 PFAS were detected in electroplating wastewater, with long-chain compounds dominating and PFOS concentrations reaching up to 3.6 × 107 ng/L. Non-target screening further identified the widespread presence of various concealed PFAS, including monohydro-substituted perfluorobutanoic acid (H-PFBA) and sodium p-perfluorous nonenoxybenzenesulfonate (OBS). Regarding treatment technologies, coagulation/flocculation showed very poor PFAS removal efficiency; flotation achieved up to 88% removal of perfluoroalkane sulfonic acids (PFSAs) but was constrained by process integration; biological treatment led to an increase in dissolved-phase PFAS concentrations; ion exchange resins achieved 98% removal of PFOS but were ineffective for short-chain PFASs due to their low affinity and rapid breakthrough; membrane technology achieved nearly 100% removal of long-chain PFASs but faced challenges, such as membrane fouling and concentrate disposal. This paper aims to provide a reference for PFAS pollution control in China's electroplating industry.