Evaluation and optimization of the process parameters for the photo-electrochemical treatment of urea using mixed metal oxide anodes

Abstract

The present study investigates the electro-oxidation (EO) treatment of urea containing wastewater using mixed metal oxide (MMO) anodes. Box-Behnken design (BBD) was employed to analyze the effects of various operational process parameters like current density (j), NaCl dose (n), treatment time (t) and pH in an EO reactor in batch mode. The performance of the treatment process was evaluated in terms of % degradation and energy consumption. Under optimum conditions, the experimental results showed that more than 94.78% of degradation of urea was achieved. Electro-oxidation has effectively reduced the TOC (90%) under optimum conditions. Attempts were made to integrate the two process electro-oxidation and photocatalysis i.e. Photoelectrocatalysis within the same treatment unit for the enhanced degradation of target pollutant. The electro-oxidation process with mixed metal oxide anode has also attained a significant removal of nitrogen by transforming into the NO3− and NH4+ through the formation of OH and reactive chlorine species. Characterization techniques like SEM-EDX and XRD have confirmed the durability of mixed metal oxide anodes even after 90 recycles of the experimental run. The total operating cost for electro-oxidation treatment of urea under optimized conditions is found to be 0.78 $/m3.