Combining Electrochemical Nitrate Reduction and Anammox for Treatment of Wastewater With Low C/N Ratio Nitrate

ABSTRACT The treatment of high concentration and low C/N ratio of nitrate wastewater is a promising and challenging research topic. Combining electrochemical reduction and anammox is a technology with great development potential for nitrogen removal from wastewater. In this work, Cu─Ag─Co cathode materials were prepared by two‐step electrodeposition method. The effect of current density and initial pH value on nitrate reduction efficiency was investigated in a single chamber electrolytic cell equipped with Cu─Ag─Co cathode and Ti/RuO 2 ─IrO 2 anode. The results showed that under the conditions of initial NO 3 − ─N concentration of 500 mg L −1 , Na 2 SO 4 concentration of 0.125 mol L −1 , current density of 10 mA cm −2 , initial pH value of 7, and treatment time of 5 h, NO 3 − ─N removal ratio was 84.5%, the concentration of NO 2 − ─N and NH 4 + ─N was 180.2 mg L −1 and 173.2 mg L −1 . Wastewater with a concentration ratio of NO 2 − ─N and NH 4 + ─N of 1.04:1 meets the influent requirements for anaerobic ammonia oxidation. Through the combination process, the final NO 3 − ─N removal ratio was 82.6%, the NO 2 − ─N concentration was 3.2 mg L −1 , and the NH 4 + ─N concentration was 26.4 mg L −1 . It provided a reference for the treatment of wastewater with low C/N ratio nitrate by combining electrochemical reduction and anammox.