Semi-conductor wastewater pre-treatment for water reclamation

• Main Author: Lee, Bing Xuan
• Other Authors: Darren Sun Delai
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Environmental engineering
• Online Access: https://hdl.handle.net/10356/172583
• Institution: Nanyang Technological University

Treatment of semiconductor wastewater is an important aspect by implementing efficient methods to treat wastewater, and to reduce the overall water usage by recycling these wastewaters. An excessively high TOC level increases oxidant demand reduces efficacy of sterilization and creates toxic byproducts. When they exist in substantial quantities in the water bodies, a higher dissolved oxygen depletion and toxicity wastewater will be released into the environment. This report provides an overview of the challenges faced in water recycling, particularly to the issues posed by dimethyl sulfone (DMSO2). DMSO2 is an addition to the spetrum of environmental contaminants. At high concentrations, DMSO2 can have adverse effects on aquatic life, primarily through changes in water quality and potentially through direct toxicity to aquatic organisms. Furthermore, DMSO2 may undergo chemical transformation in aquatic systems, leading to the formation of breakdown products with unknown environmental consequences. Standards and procedures for monitoring and removal of DMSO2 are not well-established as those for traditional contaminants. Therefore, there is a pressing need for research and development to address DMSO2 in semiconductor wastewater effectively. The aim of the report is to test the viability and efficiency of installing UV in the final polishing of the treatment process or to replace the Activated Carbon Filter (ACF) entirely with the Advanced Oxidation Process (AOP) treatment system. The report presents an approach in describing how changing part of the treatment system can lead to a cleaner effluent along with higher efficiencies. This report proposes 3 experiments with the focus on increasing the flow rate through the treatment process and reducing concentration of wastes respectively. The first experiment aims to utilize a UV radiator in the last stage of the treatment process to reduce Total organic carbons (TOC) concentration before leaving the treatment plant. Second experiment aims to replace the ACF entirely with the AOP to maintain a constant flow rate through the treatment process and keep the TOC concentration low. Monitoring metrics include plotting the concentration of TOC in milligram/liter (mg/l) with respect to time (seconds) using the different treatment methods. Using equipment that include TOC analyzer, ozonation machine, UV lamp for static batch reactor experiment to simulate the application of real-life wastewater feed. The wastewater samples went through various experiments to showcase how the change of processes affects the flow rate and concentration of effluent. With the results obtained, the experiments will thus create an optimal treatment for semiconductor wastewater to save costs and reduce overall usage of water by recycling. These results provide opportunities for further optimization for the semiconductor wastewater treatment where introducing new equipment and methods to reduce the TOC concentration will prove to be more efficient.