Study on the Advanced Treatment of Coking Wastewater by a Hierarchical Oxidation System Built with Chlorine Dioxide and Fenton

以某焦化厂焦化废水生化出水为研究对象，筛选出由二氧化氯(ClO2)和芬顿(Fenton)构建的分级氧化体系法进行深度处理，研究pH、ClO2浓度以及Fenton试剂投加量、配比对废水COD去除效果的影响。得到分级氧化体系深度处理焦化废水的最佳条件为：H2O2 和COD质量比为1.6、50 mg/L ClO2、pH = 8和n (H2O2) : n (Fe2+) = 3:1，反应时间60 min，在此条件下COD的去除率为93.32%，处理后出水水质满足《炼焦化学工业污染物排放标准》(GB16171-2012)表2的直接排放限值。同时自由基捕获实验表明分级氧化体系中羟基自由基(·OH)起主导氧化作用。焦化废水生化出水处理前后的GC-MS结果表明：分级氧化体系能去除焦化废水生化出水中芳香蛋白类物质和大部分类腐殖酸物质，含氮类有机物被完全降解，部分芳香族化合物中的苯环裂解，大部分长链有机物断裂为短链有机物，整体分子量减小，并部分矿化。The biochemical effluent of coking wastewater of a coking plant was selected as the research object, and the fractional oxidation system method constructed by ClO2 and Fenton was selected for further treatment, and the effects of pH, ClO2 concentration, dosage and ratio of Fenton reagent on COD removal were studied. The optimal conditions for the advanced treatment of coking wastewater by the hierarchical oxidation system are as follows: The mass ratio of H2O2/COD (mass ratio) = 1.6, 50 mg/L ClO2, pH = 8 and n (H2O2): n (Fe2+) = 3:1, and the reaction time is 60min. Under these conditions, the COD removal rate is 93.32%. The treated effluent meets the direct emission limit in Table 2 of the Pollutant Discharge Standard for the Coking Chemical Industry (GB16171-2012). The experiment of free radical capture shows that hydroxyl radical (·OH) plays a leading role in the hierarchical oxidation system. The GC-MS results before and after the biochemical effluent treatment of coking wastewater showed that the hierarchical oxidation system could remove most of the aromatic protein substances and humic acid substances in the biochemical effluent of coking wastewater, the nitrogenous organic matter was completely degraded, the benzene ring in some aromatic compounds was cracked, most of the long chain organic matter was broken into short chain organic matter, the overall molecular weight was reduced, and part of the mineralized.