| Coking wastewater is a kind of complex wastewater, which contains a large number of toxic and hazardous substances. By conventional biological treatment, effluent quality will not meet the standards and physical or chemical treatment costs higher. In a variety of coking wastewater processing technology, the use of the predominant bacterium has demonstrated its unique role. By the measurement of dehydrogenase activity and biomass, this paper analyses the synergistic reaction in predominant bacterium. Then different co-metabolic matrixes are added to further study on the predominant bacteria's impact on the removal of COD.After expanding culture of sifted seven predominant bacterium (EWV17,DPⅢ20,EPⅣ1,EWV7,DPⅢ16,DPⅢ21,EPⅣ2), gradually increase the proportion of coking wastewater for acclimation culture, then culture the predominant bacteria respectively, measure the change of dehydrogenase activity and biomass, sift the united predominant bacterium (DPⅢ20+ EPⅣ2+DPⅢ16+ DPⅢ21) whose dehydrogenase activity has increased. Then carry out the initial experimental study on the growth characteristics of the united predominant bacterium. Based on the experimental results, the united dominant bacterium should be cultured in 30℃, pH 7.2 for 24 h for use.After the immobilization of sifted united predominant bacterium and activated sludge in various proportions, carry out the comparative analysis, and the ratio of the two should be controlled in 4:1. Under this ratio, measure the COD removal under different temperature, pH and dissolved oxygen concentration, it proved that the temperature should be controlled in 30～35℃, pH in 7.0～7.5, dissolved oxygen in 3.0 to 3.5 mg / L. According to the change trend of COD concentration and dehydrogenase activity within 48h, it is proved that the reaction time should be controlled in 24h.Control the same influent concentration and reaction condition, add different united predominant bacteria to do a parallel group experiment. It is proved that by adding single dominant bacteria (EPⅣ2) the COD removal rate increases only 6.3%, while by adding united predominant bacteria (DPⅢ20+ EPⅣ2 +DPⅢ16+ DPⅢ21), the COD removal increases 10.2%. The results show that the selected united predominant bacteria can break down refractory material more effectively by synergistic reaction and enhance the removal rate of COD.Add different co-metabolic matrixes in reaction system which contains united predominant bacteria. When co-metabolic matrixes as carbon source, the removal rate of COD will increase by different degrees. Especially when glucose is co-metabolic matrixes, the COD removal can enhance effectively. Control reaction condition, add predominant bacterium once and react for one month, measure the everyday COD, the removal rate of color. The results show that in the previous 15 d～20d, the removal of COD and color is higher.This study shows: The measurement of dehydrogenase activity and biomass can determine the synergistic reaction in predominant bacterium, and the selected predominant bacteria group can enhance COD removal effectively. At the same time, by adding co-metabolic matrixes, the removal of COD can be further increased. The results of the experiment obtained in this paper provide references for further research and utilization.
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