Catalytic Ozonation Oxidation-Biofilm Coupling Process For Petrochemical Wastewater Treatment Research

The petrochemical industry produces a large volume of waste emission endangering the environment. The characteristics of petrochemical production determine the universality and complexity of its pollution. Numerous researchers have conducted a lot of studies for petrochemical wastewater treatment techniques, including coagulation, electrochemical oxidation, Wet oxidation, photocatalytic oxidation, catalytic ozonation, biofilm, MBR, BAF etc.. With the promulgation of the new national standard of wastewater emission,Liaoning Province tntegrated wastewater discharge standard? DB21/1627-2008?, the original wastewater treatment facilities and techniques have been unable to meet the requirements,thus it is essential to upgrade and modify the existing wastewater treatment facilities and technics to improve the quality of wastewater treated and satisfy the rigorous standard and discharge.Due to the characteristics of high concentration, high COD and NH₄⁺-N, low carbon nitrogen ratio as well as poor biodegradability of petrochemical wastewater, the traditional physicochemical and biological treatment methods cannot solve the problem. Therefore, we reasonable design and exploit a new combined technology aimming at the high-efficient removal the carbon and nitrogen from the petrochemical wastewater in this paper.Firstly, the pretreatment process using the catalytic ozonation technique conducted to improve wastewater biodegradability and thereby create the favorable conditions for subsequent biological treatment. Then, the wastewater after treated by the catalytic ozonation proceeded into the anoxic-aerobic biofilm to achieve the efficient elimination of carbon and nitrogen. Finally, the combine technics of “catalytic ozonation oxidation-biofilm” coupling process was established and the treatment efficiency of the petrochemical wastewater ware investigated in detail.The designed catalyst for the catalytic ozonation process was synthesized through the dipping-drying-roasting procedure with commercial g-Al₂O₃ as supports and Ce?NO₃?₃ and Mn?NO₃?₃ as precursors. Different techniques such as SEM-EDX?XRD,BET and XPS were applied to characterize the morphology, structure and chemical composition, etc..Experimental results showed that the CODCr removal rate of petrochemical enterprises' s outfall wastewater reached as high as 60.3% through the catalytic ozonation process, under the optimal operation conditions, satisfing emission standards. After analyzing the hydrolysisand acidification processes of biofilm by the upflow non-woven fabrics biofilm reactor, the average removal rate of CODCr and TN of ca. 71%, and 70.5%, respectively, were obtained from the catalytic ozonation oxidation-biofilm coupled process, both attaining the emission standard.The integrated catalytic ozonation oxidation-biofilm technology can effectively enhance CODCr and total nitrogen removal of refractory organic contaminant in petrochemical total outfall wastewater and the effluents finally meet the Liaoning Province wastewater discharge comprehensive standard. The coupled catalytic ozonation oxidation-biofilm technics provides a potential technical support for domestic similar wastewater treatment.