Simultaneous removal of fluoride and disinfection by-product precursors through Zr salt enhanced coagulation

Increasing fluoride (F - ) in groundwater sources due to geological and anthropogenic activities poses a threat on human health. Simultaneous removal of F - and natural organic matter (NOM) is challenging during the drinking water treatment. In this study, the coagulation performance of a novel Zirconium (Zr) salt coagulant for removing F - and disinfection by-products (DBPs) precursors was tested against with a traditional aluminum sulfate (Alum) coagulation. F - can be effectively removed by both Alum (25.5 %-93.4 %) and Zr salt (41.8 %-94.2 %) coagulation at a wide pH ranging from 4.5 to 8.5, while the metal residual in the Zr salt coagulation effluent (< 0.05 mg Zr/L) was much lower than that in Alum coagulation effluent (> 0.1 mg Al/L). In the case of Zr salt enhanced coagulation, the maximum removal of F - was 64.8 % at pH 4.5. The adsorption of F - onto the Zr salt precipitates through the electrostatic attraction and ion-exchange was the main route for removal of F - . Meanwhile, the formation potential and the calculated toxicity of DBPs were reduced by 43.1 % and 41.8 % in Zr salt enhanced coagulation, respectively. The enhancement in removing low molecular weight (LMW) acids contributed to the effective control of DBPs formation and associated toxicity in Zr salt enhanced coagulation. Hence, Zr salt coagulants show great promise in controlling F - and highly toxic DBPs precursors simultaneously during drinking water treatment.