Nickel, cyanide, zinc, and copper removal from the effluent using photo-electrocoagulation-oxidation

Abstract

One emerging approach for eliminating organic and inorganic pollutants from wastewater is electrocoagulation, often coupled with traditional methods to enhance efficacy. This study investigates the simultaneous elimination of nickel (Ni), cyanide (CN), zinc (Zn), and copper (Cu) from the natural wastewater of a gold processing plant using the photo-electrocoagulation method with ozone as an oxidizing agent (ECOUV), both in continuous and batch modes, produced in situ. When performing the test in batch mode, CN, Ni, Cu, and Zn were removed at their peak of 100, 79.1, 100, and 89 %, respectively, at pH=10 and at i = 15 mA/cm² using graphite-aluminum cathodes and stainless-steel anodes for 60 min without injecting oxidizing agent and solely based on in-situ ozone production. During the continuous mode test, the highest removal efficiencies achieved were 100 % for CN, 73 % for Ni, 100 % for Cu, and 78.8 % for Zn, all under identical operational parameters. These results confirm that ECOUV holds promise as a feasible approach for removing pollutants from the wastewater discharged by mineral processing facilities.