Removal of short- and long-chain perfluorinated compounds from surface water by coagulation

Per- and poly-fluorinated compounds (PFCs) are persistently found during drinking water treatment processes, which can also be found in tap water. However, the mechanisms for removing PFCs during drinking water treatment processes have not been fully understood. In this study, we investigated the effect of coagulation on the removal of short- and long-chain PFCs. The PFCs mixture (C5-C10) resulted in a lower removal efficacy via coagulation treatment, and the average removals of selected PFCs were found to be below 5%. Only long-chain perfluorodecanoic acid (PFDA) (C10) and perfluorooctanesulfonic acid (PFOS) were significantly removed via coagulation. The removals of suspended particles and bacterial cells via coagulation were correlated with the reduction of PFDA and PFOS. However, higher turbidity, humic substances, and biopolymers in the source water were found to significantly reduce the removal efficiency of PFDA and PFOS, resulting in insignificant changes between the PFC species. We concluded that coagulation was not effective in removing selected PFCs, hence, a multiple-barrier treatment strategy is needed for PFC removal.