Optimization of High-Strength Semiconductor Wastewater by Sequential Fenton Oxidation and Gas-Induced Ozonation

Abstract

Treatment of organic-containing wastewater from a semiconductor plant treated by chemical oxidation was experimentally investigated. The wastewater was characterized by strong color, high chemical oxygen demand (COD) and low biodegradability. Treatment of this wastewater by traditional activated sludge method was essentially impossible. In the present work, advanced chemical oxidations by Fenton’s reagent and ozonation were utilized to tackle the problems of wastewater color and low biodegradability. To facilitate the particulate removal after Fenton oxidation, chemical coagulation using polyaluminum chloride and polymer was adopted as an integral part of the Fenton process. Experimental tests were conducted to determine the effectiveness and the optimum operating conditions of the chemical oxidation methods. Test results demonstrate that the two advanced oxidations were able to lower the wastewater COD concentration from as high as 15,000 mg/L to below 150 mg/L and completely eliminating the wastewater color, resulting in very good quality of the treated wastewater. A generalized kinetic model was employed to describe and elucidate the oxidation mechanisms of oxidation processes and the kinetic parameters of the models were appropriately identified using the test data.