Optimization of ammonia and COD removal from municipal wastewater effluent by electrochemical continuous flow reactor equipped with Ti/RuO2 and Cu foam

Abstract

The aim of the present work was to study an electrochemical continuous-flow reactor for the removal of ammonia nitrogen (NH4+N), its by-product, and Chemical Oxygen Demand (COD) from synthetic and real municipal wastewater effluent. In this study, Ti/RuO2 electrode was prepared by the thermal decomposition method for the removal of NH4-N and COD. Characterization of the Ti/RuO2 was accomplished using FE-SEM, EDS, AFM, and XRD. Cyclic voltammetry and Tafel curves were used for the electrochemical feature of the Ti/RuO2 electrode. Box-Behnken Design (BBD) method was used to optimize the operating conditions. The effects of four independent parameters including the initial concentration of NH4+ (10–30 mg/L as N), Cl− concentration (100–500 mg/L), HRT (30–100 min), and current (0.4–1.4 A) were examined using continuous experiments for the removal of NH4+N and COD. Characterization results confirmed that RuO2 was successfully coated on the surface of titanium mesh. Optimum conditions for Cl− concentration, HRT, and current were 490 mg/L, 100 min, and 1.36 A, respectively for an effluent concentration of 30 mg/L NH4+N and 30 mg/L of COD. Under these conditions, the removal efficiencies of NH4+N and COD were respectively 97.79 and 89.64 %, and the concentration of NO3−N was 1.93 mg/L. This work highlights the importance of an electrochemical continuous flow reactor for further removal of nitrogen and COD from the effluent of municipal wastewater treatment plants.