| The experiment used the BAC craft to treatment the sewage, in order to make the water reused. The sewage after secondary treatment is the primary water of the experiment, and then pumps it into a 100cm-height BAC filter with the flow quantity of 1L/h, 2L/h and 4L/h.The process achieved a remarkable effect of tertiary treatment of domestic wastewater. The effluent's turbidity, NH3-N, COD and petroleum content can attract the standard for reuse. The consistency of COD has changed from 107.88mg/l to 21.05mg/l, it was reduced 80.4%. The consistency of NH3-N has changed from 14.5305mg/l to 4.2995mg/l, it was reduced 71.2%. The consistency of turbidity has changed from 19.55NTU to 0.736NTU, it was reduced 96.2%. The consistency of petroleum has changed from 14.67mg/l to 4.87mg/l, it was reduced 66.8%.BAC's clearance of COD was increased with the reducing of flow quantity. So reduce the flow quantity as well as increase the HRT can raise the clearance of COD greatly. BAC's clearance of COD was also changed with the BAC's height. With the increase of the height of BAC, the clearance of COD was raised. But the clearance of COD happened in the upper of the BAC.The volume loading of BAC changed from 1.117kgCOD/cm~3·d to 0.290 kgCOD/cm~3·d, under such the fluctuations, BAC's clearance of COD was more than 80%, the effluent's consistency of COD was less than 25mg/l. So the BAC has good ability of shock resistance. But when the consistency of COD was more than 200mg/l, the quality of the effluent was dropped. The effluent's consistency of COD was more than 35mg/l. So when the consistency of COD was more than 200mg/l, the BAC craft was unsuitable.Based on the analysis of bioreactor kinetics, a three-stage kinetic model was proposed to characterize organic substance removal in the BAC filter. Because the biomass decreases with the depth of the BAC filter, the rate coefficient of the first-order reaction decreases with the filter depth as well. |
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