Operational conditions of electrochemical oxidation process for removal of cyanide (CN-) in real plating wastewater

An electrochemical oxidation process was applied to remove cyanide (CN-) from real plating wastewater. CN- removal efficiencies were investigated under various operating factors: current density and electrolyte concentration. Electrolyte concentration positively affected the removal of both CN- and Chemical Oxygen Demand (COD). As the electrolyte concentration increased from 302 to 2,077 mg Cl-/L, removal efficiency of CN- and COD increased from 49.07% to 98.30% and from 23.53% to 49.50%, respectively, at 10 mA/cm2. Current density affected the removal efficiency in a different way. As current density increased at a fixed electrolyte concentration, CN- removal efficiency increased while COD removal efficiency decreased, this is probably due to lowered current efficiency caused by water electrolysis.