Study On Advanced Treatment Of Chemical Wastewater By Ozone Oxidation + BAF Combined Process

To achieve the goal of characteristic organic contaminants’removal from centralized wastewater in chemical industrial park, and to solve the problem of the selection of wastewater treatment processes for obtaining effluent’s quality in compliance with regulations, combined technologies of ozonation and biological aerated filter (BAF) were applied in both lab and pilot scales in this work for deep treatment of the effluent from centralized wastewater treatment plant in a chemical industrial park. The synthesis routes of catalysts and the effect of catalysts’types in the unit process of ozonation on the treatment performance were systematically investigated by several characterization methods. The effects of different sequences of combined technologies, ozone dosage, hydraulic retention time and pH on the treatment efficiencies were studied for obtaining optimal operation conditions. Meanwhile, fast-start-up conditions of BAF were also optimized. The improvement of both biodegradability of wastewater and degradation of organic contaminants were tested, through combination of ozonation and BAF.The experimental results demonstrated that, the treatment performances were similar between different sequences of treatment technologies from the viewpoint of removal efficiencies of both COD and UV254. However, from another view of chromaticity removal, it was better to place the ozonation step after BAF. The three-component-catalyst of Mn-Cu-Sn was selected due to its better performance. By experiments in both lab and pilot scale, the optimal operation conditions for ozonation were selected to be 30-50 mg/L of ozone dosage and 1 h of hydraulic retention time. Under this condition, the removal efficiencies of COD and UV254 were 12% and 37%, respectively. Besides, the operation conditions for BAF were optimized to be 3:1 of the ratio between air and water, and 6 h of hydraulic retention time. In this situation, the the removal efficiencies of COD and UV254 could reach to 33% and 50%, respectively.3-D fluorescence analysis indicated that, the biodegradability of wastewater, as well as the degradation degree of toxic organic contaminants, was significantly enhanced via ozonation. At last, the cost of the combined process in this work was 0.5675 yuan per ton through a comprehensive calculation.