LAUSR

Abstract Reverse osmosis (RO) concentrate becomes a new knotty problem in water treatment for its high concentrated salts and complex pollutants. In this study, we presented a photoelectrocatalytic (PEC) chloride-radical (Cl•) system to efficiently remove its pollutants including total nitrogen, natural organic matter and emerging pollutants simultaneously in taking advantage of pre-existing chloride and sulfate salts as electrolytes. NH4+-N, humic acid and emerging pollutants of nitrosodiethylamine and bisphenol A were used as model pollutants. A WO3|[Pd- Cu/NF] electrode couples were used in the PEC system, and HO• and Cl• radicals were generated on the surface of WO3 photoanode. Organics including humic acid and emerging pollutants were degraded by HO•, and NH4+-N was efficiently oxidized to N2 with the selective reaction of Cl• and NH4+. NO3--N over oxidized from NH4+-N was selectively reduced into N2 on [Pd-Cu/NF] cathode. The results showed that the total nitrogen (TN) and total organic carbon (TOC) removal rate were 99.90% and 50.95% in 180 min for the model RO concentrate with 28 mg/L NH4+-N and 20 mg/L humic acid. The emerging pollutants including nitrosodiethylamine and bisphenol A performed removal rates of almost 100%. This study offers a novel, efficient and eco-friendly PEC system for deep purification of RO concentrate.