Evaluation of Direct and Alternating Current Electrochemical Process using Aluminum and Zinc Electrodes in the Nitrate Removal from Aqueous Solutions

Nitrate is one of the most important pollutants in surface and groundwater. The present study aimed to evaluate the effect of different parameters on the performance of the electrical coagulation process in the removal of nitrate from contaminated water.

This study was conducted based on an experimental design and the statistical community was urban water. A cylindrical batch reactor with aluminum and zinc electrodes (monopolar arrangement) was used to remove 100 mg/L nitrates. The experiments were performed three times in direct and alternating currents using standard methods. Factors of pH, contact time, and weight of electrodes were evaluated, and the results were reported in tables and graphs.

Nitrate removal efficiency (87.4%) was higher in direct current, as compared to that in alternating current (39.1%). The highest nitrate removal efficiency of 87.4% was obtained in direct current, in comparison with 61% for alternating current. As the contact time increased, the pH of the solution increased in two currents, from 7 to 11.21 and 8.47, respectively. Total dissolved solids (TDS) at optimal conditions in alternating and direct current were 79 and 126 mg/L, respectively. After 30 min of settling, the produced sludge was measured as 17.66 and 280 mL/L in direct and alternating current, respectively. The weight of the anode electrode had the greatest decrease in direct current.

The results of this study pointed out that the process of electrical coagulation could reduce the concentration of nitrate to less than the standard. Nitrate removal with the direct current was performed with less energy consumption and cost than alternating current. As a result, the use of optimal conditions increases the process efficiency in the electrochemical removal of nitrate.