Treatment of catalyst wastewater through an environmentally friendly electrodeposition-precipitation-electrooxidation coupling process: Recovery of copper and silicate, and removal of COD

•99.8% of copper in the Cu-TEPA complex was recovered at the cathode through electrodeposition process.•High concentration of silicate in water has a restraining effect on the anodic electrooxidation process.•Amorphous silica generated at the anode surface can be avoided by keeping the initial pH higher than 12.9.•89.7% of silicate can be removed when CaCl2 was used as the precipitant and the Ca:Si molar ratio was 1:1.•TEPA was easier mineralized through active chlorine indirect oxidation process.