Application of Cu@Cu foam and RuO2@Ti for removal of nitrogen compounds and organic matters from non-standard treated municipal wastewater by continuous electrochemical process: Optimization and mechanism

Public health, potable water supplies, and ecosystems are endangered by the disposal or reuse of non-standard effluents of wastewater treatment plants. To achieve the Sustainable Development Goals (SDG 6) and USEPA quality standards, this work utilized an innovative electrochemical technique with continuous flow. Cu@Cu foam and RuO2@Ti were prepared for NO3 reduction and NH4 and COD oxidation, respectively. The characterization of electrodes was performed by XRD, EDS, FTIR, FE-SEM, and CV analysis. The effects of parameters including NH4 concentration (10-30 mg N/L), NO3 concentration (4-12 mg N/L), current (0.5-1.5 A), and Cl- concentration (100-400 mg/L) were examined for the removal of NH4, NO3, and COD. Characterization results confirmed that Cu and RuO2 were successfully coated on the surface of electrodes. Operating parameters were optimized using response surface methodology. The ideal conditions for current, Cl- concentration, and HRT were 1.5 A, 347.7 mg/L, and 120 min, respectively for concentrations of 9 mg /L NO3-N, 30 mg/L NH4-N, and 30 mg/L COD. Under these conditions, NO3-N, NH4-N, and COD removal efficiencies were 78 %, 97.8 %, and 61.2 %, respectively. The proposed electrochemical process was a sustainable technology for the concurrently removal nitrogen and carbon with advantages including environmental compatibility, versatility merits, and simplicity.