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

Abstract

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.