Perfluorochemicals in Korean Wastewater Treatment Plants: Implications on Sources and Monitoring

The occurrence of perfluorochemicals (PFCs) in two wastewater treatment plants (WWTPs) in Korea, Plant I and G2, is investigated from a year-round sampling campaign. Plant I influent is characterized by the dominance of perfluorohexanesulfonate showing 10.8-fold higher per capita mass discharge value in the service area than that of Plant G2 service area. Plant G2 influent shows the dominance of perfluorooctanote and perfluorohexanoate, whose per capita mass discharge values are 3.7- and 11.8-fold higher than those of Plant I, respectively. Contrary to the dramatic difference of concentration and per capita mass discharge pattern of PFCs, the per capita mass discharge values for typical wastewater quality indicators are nearly identical for two WWTPs. This result implies that industrial contribution is significant for the PFC loading at the two WWTPs despite the fact that Plant I and G2 influents are officially reported to include only 0.4% and 7.5% of industrial wastewater in flowrate, respectively. This disagreement between the implication from the PFC data and the official report suggests the need to improve our knowledge on the impact of industrial sources on PFCs in WWTP influents, including those sources that are not officially registered or are poorly managed. The PFC fate during the wastewater treatment is slightly different between the two WWTPs, which can be partially explained by the different biological treatment processes applied. Seasonal variations in PFC concentrations observed in this study suggest that any monitoring program should be performed at least on a seasonal basis.