Optimization of the electrochemical reduction process and ORP effects in nitrate removal.

Abstract

Nitrate contaminated water resources, a huge environmental problem for countries, including our own. This research aims to evaluate the efficiency of the electrochemical process for the removal of nitrate from the aqueous solution by direct and alternating current. Experiments were done by the Taguchi method, including electrode array, time exposure, voltage, pH, and the initial concentration of nitrate. Minitab 17 and SPSS 18 software were utilized to design and data analysis. In detail, the connection of the electrodes was monopolar, and the direct current (DC) has a greater efficiency as alternating current (AC) in the nitrate removal (p > 0.001). In AC, the nitrate initial concentration, voltage, electrodes material, contact time, and pH have the most effect on the nitrate removal. The optimized conditions for nitrate removal include Al-Al electrode, pH of 7, a voltage of 30 V, and nitrate initial concentration of 100 mg/L with the contact of time 150 min. Selection of appropriate materials for electrodes construction, adequate voltage, and removal of intervention agents from aqueous solution led to greater removal efficiencies. The optimized conditions that can reduce the aqueous solution ORP with high speed and the electrochemical reactor efficiency for nitrate removal were increased. PRACTITIONER POINTS: Electrochemichal (EC) process is evaluated for treatment of nitrate wastewater for the first time. High removal efficiency (over 95%) from nitrate wastewater was obtained. Minimizing energy consumption and maximizing nitrate removal were simultaneously achieved in the integrated single EC process.