Recovery of Copper from Semiconductor Wastewater Using a Graphite-Anode Electrowinning System

Copper is widely used in semiconductor manufacturing, but elevated concentrations in wastewater pose environmental and public health risks. In response to the stringent dissolved copper effluent standard of 1.0 mg L-¹ imposed by the Department of Environment and Natural Resources (DENR) Administrative Order (DAO) 2021-19, this study aimed to identify the optimal electrode materials, determine the optimal operating conditions for copper electrowinning, and evaluate a scaled-up electrowinning prototype for semiconductor wastewater treatment. The study involved electrode material screening, laboratory-scale cell optimization, and prototype scale-up validation. Graphite and copper were identified as the optimal anode and cathode materials, respectively, due to their favorable electrochemical performance and minimal metal leaching. Optimized electrode spacing, current, and cell configuration were subsequently applied to a scaled-up system. Proof-of-concept testing reduced dissolved copper concentrations from 50 mg L-¹ to as low as 0.56 mg L-¹. Under scaled-up conditions using actual semiconductor wastewater with initial copper concentrations of approximately 8,000 mg L-¹, the optimized system achieved copper removals exceeding 99.9%, reducing concentrations to typical final values of approximately 4.19 mg L-¹. Scaled-up runs exhibited Faradaic Current Efficiencies of 17–21% and Specific Energy Consumption of 14.7–15.8 kWh kg-¹ Cu recovered. While downstream processing is required to meet the absolute DAO 2021-19 discharge limit, these results demonstrate that high-rate electrowinning functions as a highly effective resource recovery and cleaner production pretreatment technology, significantly mitigating heavy metal pollution at the source.