A Combined Biological and Advanced Oxidation Process for the Treatment of Wastewaters from the Microelectronics Industry

Micro-electronics manufacturing is one of the fast-growing industries in America, Europe, Asia and Australia, and the semiconductor market grew by 61% in North America in 2011 compared to the previous year. Exponential growth of thin-film-transistor liquid crystal display (TFT-LCD) manufacturing generates a large amount of high-strength wastewater containing monoethylamine, dimethyl sulphoxide, tetra-methyl ammonium hydroxide (TMAH), and many other organic and inorganic compounds. This study was focused to develop a sustainable and cost-effective processto treat the wastewaters from the micro-electronics industries. Several bench-scale and pilot-scale studies were conducted to investigate complete degradation and/or removal of TMAH employing biological (activated sludge) and chemical (advanced oxidation) processes. Combination of aerobic oxidation followed by advanced oxidation and biological denitrification was the most successful option for TMAH degradation and nutrient removal from TFT-LCD wastewaters. The aerobic-AOP-anoxic system removed >98% TMAH, Total Organic Carbon (TOC), ChemicalOxygen Demand (COD) and >96% Total Nitrogen (TN) from wastewater containing TMAH of 5,000±100 mg/L, TOC of 2800±50 mg/L and TN of 750±30 mg/L. This patent pending biological-chemical process will benefit micro-electronics industries and the ailing publicly owned treatment works (POTWs) attributed to the increased nutrient loadings coupled with stringent regulations.