| Coke plant wastewater contains complex components, which are threatening the propagation and human health. So far, the treatment combining the physicochemical method with biochemical method is more suitable for coke plant wastewater treatment .The Anaerobic-Anoxic-Oxic system is a most widely-used biochemical process, it can enhance the degradation efficiency and have a simple equipment.An Anaerobic-Anoxic-Oxic system was used to treat coke plant wastewater in this paper. At first, the activated sludge was fostered and tamed in the aerobic reactor, this work lasted more than a month before it was finished. During this period, the biodegradation characteristic of the major pollutants was studied. After this, we began to study the operating condition of the aerobic reactor, which contain temperature, pH, hydraulic retention time(HRT), reflux ration.Based on the analysis of the experiment result, we know that while the influent is 2L/h, the best operation parameters in aerobic reactor under the conditions of this experiment obtained as follows: temperature is 25℃～35℃; pH range is 6.5～7.5; HRT is about 60h; reflux ration is 5:1～6:1.After experimental study, we carried out a engineering practice in a coke plant of Shan xi province. During the period of the acclimation of the activated sludge, we found that while the temperature of the aerobic stage reached 20℃, the degradation efficiency seems to be ideal, beneath this point, the bacteria growth was easily influenced. In the wastewater treatment system,the pH range of the system is 6.5～7.5, HRT of the aerobic stage is about 36h, reflux ration is 3:1～6:1, influent water is about 20m3/h. The effluent quality of the A2/O system can meet the classⅠcriteria specified of Integrated Wastewater Discharge Standard (GB8978-1996).During measuring time, the effluent NH3-N is below 1.0mg/L in normal operations, but the average NH3-N in the effluent is 3.9 mg/L because of a few fluctuation of influent; the effluent COD below 100mg/L. |
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