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

Abstract

An environmentally friendly coupling process of electrodeposition—chemical precipitation—electrooxidation was explored to recover copper and silicate, and remove COD, showing a promising effect in treating catalyst wastewater. The feasibility and the key influencing factors of the process were investigated. The results showed that more than 99.8% of copper and 89.7% of silicate were recovered through the electrodeposition process and precipitation process, and 96.4% of COD was removed in the electrooxidation process. The purification of recovered copper was higher than 99.12% and the residual COD was lower than 500 mg/L. A higher initial pH value (>12.9) or the addition of a certain amount of NaCl is essential in avoiding the fouling of the anode in the electrodeposition process. In the chemical precipitation process, CaCl2 was selected as the precipitator, and the dosage of Ca: Si molar ratios of 1:1 was feasible for silicate removal. After processing, the content of copper and COD met the discharge standard.