TSMC Realizes Circular Economy; 12-inch Fabs Achieve Copper Ion Emission Concentration Target Ahead of Schedule
In order to fulfill its mission on green manufacturing, the development of water pollution prevention technology is an important part of TSMC's water management. Following the innovative work of electroplating copper rods with high concentration of copper-containing waste liquid, TSMC further executed three steps of copper ion reduction and pollution reduction in 2019; that is, source drain shunting, intermediate treatment, and by-product value increase. TSMC continuously optimized the treatment efficiency, reduced the discharge concentration, and successfully concentrated the waste to high-value products. In September of 2019, all 12-inch fabs reached the annual target of reducing emission concentrations of less than 0.1ppm (drinking water copper standards: 1ppm) ahead of the schedule.
Shunt Wastewater in Different Concentration, Optimize the Recipe, and Reduce Dosage of Chemicals
In order to find out the most suitable dosage for the treatment of copper waste liquid, TSMC conducted a comprehensive review of the usage and discharge of raw materials. After testing, evaluations and analysis of the results for many times, we found the most suitable dosage for different discharge concentrations.
In 2019, all 12-inch fabs used the low-concentration copper-containing waste liquid (<2ppm) shunt treatment system, effectively reducing the generation of mis-synthesis ions which the copper ion capture efficiency per unit dose affecting copper capture efficiency and bond dissociation strength, increasing from 20% to 30%, and reducing the amount of chemical dosage and unwanted by-products to avoid the second pollution of copper dissolution.
TSMC Treatment Procedures of Copper-Containing Liquid Waste
Continue Recycling Spirit; Treat Concentrated Water of By-products Again to Promote Resource Regeneration
In addition to improving the recycling efficiency of low-concentration waste liquid, TSMC conducted the high-pressure reverse osmosis treatment process in 2019 in accordance with the regulatory standards for the general concentration of copper-containing waste liquid, and further re-directed the treated wastewater to the wastewater treatment system again. After the second treatment, the copper concentration of the discharged water was successfully reduced to 0.06 ppm, and its improvement rate reached 14%. At the same time, the reduced copper-containing wastewater can also be formed into building material by using coagulation sedimentation.
Establish Low-concentration Wastewater Concentration System to Increase By-product Value and Fully Realize Circular Economy
In 2016, TSMC was industry pioneer to introduce the recycling of copper sulphate to electronic grade copper materials. In 2019, it further evaluated to establish a " regenerated wastewater electroplating recycling system” to concentrate the waste liquid into copper rods. It broke the cycle of the medium and low concentration copper-containing waste liquid to the building materials through the metal capture agent, enhancing the economic value. By selecting the concentration of resin and regenerated waste liquid, the system regenerates the low concentration copper ions adsorbed by the cationic resin tower to copper rods by electroplating. After the system is completed, it will 100% replace the existing discharge treatment process, and further fulfill the vision on circular economy to have zero copper-containing waste liquid discharge and resource regeneration.