Treatment of organic wastewater discharged from semiconductor manufacturing process by ultraviolet/hydrogen peroxide and biodegradation

This study investigates the feasibility of using a two-stage process combining a photochemical oxidation process (UV/H₂O₂) and a biological fluidized-bed system to treat dilate-organic wastewater discharged from semiconductor manufacturing facilities. This combined process has the merits of decomposing recalcitrant organic chemicals into intermediate products more amenable to biodegradation, thereby achieving high degree of mineralization of organic compounds that are otherwise toxic to aerobic biodegradation. Six organic solvents, including propylene glycol methyl ether acetate, ethyl lactate, tetramethylammonium hydroxide, 1-methyl-2-pyrrolidone, isopropanol, and phenol, were evaluated due to their common applications in various wafer fabrication processes. The optimal operating conditions (H₂O₂ dosage, pH, exposure time) for the first-stage UV/H₂O₂ were determined for each chemical, and a nominal condition was selected for the ensuing biodegradation, experiments. GC/MS analyses demonstrated that UV/H₂O₂ indeed decomposed the chemicals into smaller fragments that could be effectively mineralized by aerobic biodegradation.