Fate and Risk Assessment of Perfluoroalkyl Substances (PFASs) in Water Treatment Plants and Tap Water in Bangkok, Thailand

Perfluoroalkyland Polyfluoroalkyl Substances (PFASs), especially Perfluorooctanoic acid (PFOA) and Perfluorooctanesulfonate (PFOS), were found to contaminate the natural water sources serving as a raw material in producing tap water. The main purpose of this study was to measure the quantities of PFASs in both conventional and advanced water treatment processes, and of the PFASs contaminated tap water in various forms, with comparison made between tap water and water passing through drinking devices. It was found from the investigation that the conventional treatment process using coagulation, sedimentation, filtration and chlorination was incapable of removing PFASs, and that the concentration of effluent increased more than 27% compared to the influent. On the contrary, advanced water treatment process using GAC filter and RO was able to remove more than 86% of PFASs. The tap water was found to contain PFASs at 0.58-1.15 ng/L. However, a comparison between the average of the water passing through drinking devices and direct faucet showed insignificant difference, but the concentration of PFASs decreased by a small amount when passing a filter-equipped device.