Abstract

Nitrate contamination is a great concern all over the world. However, the conventional biological processes like the modified Ludzack-Ettinger process are time-consuming. Accordingly, a rapid process for nitrate removal is desired. We conceived an electrochemical process for rapid removal of nitrate, which contained electrochemical reduction of nitrate to ammonia and electrochemical break-point chlorination of ammonia. In this research, we investigated effects of operational parameters such as volumetric electric charge, flow rate and chloride ion concentration on electrochemical nitrate removal. A hand-made divided flow cell with a copper mesh cathode, a platinum-coated titanium anode and a cation exchange membrane as a separator was developed as well as applied to the treatment of synthetic water containing 1.42 mM of nitrate at various volumetric electric charges, flow rates and chloride ion concentrations. As a result, it was observed that the flow cell operated at a flow rate of 20 mL/min, chloride ion concentration of 800 mg/L, volumetric electric charge of 5,100 C/L and at pH 7 successfully removed nitrate from 1.42 mM to 0.43 mM without ammonia and nitrite accumulation within 1 minute contact time. Consequently, the electrochemical technique was thought to be feasible for the rapid removal of nitrate from water streams.