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/RuO2─IrO2 anode. The results showed that under the conditions of initial NO3−─N concentration of 500 mg L−1, Na2SO4 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, NO3−─N removal ratio was 84.5%, the concentration of NO2−─N and NH4+─N was 180.2 mg L−1 and 173.2 mg L−1. Wastewater with a concentration ratio of NO2−─N and NH4+─N of 1.04:1 meets the influent requirements for anaerobic ammonia oxidation. Through the combination process, the final NO3−─N removal ratio was 82.6%, the NO2−─N concentration was 3.2 mg L−1, and the NH4+─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.