| In order to study the modified A~2+OSA step feed process in sludge reduction under the condition of the main pollutants in raw water removal, were constructed by modified A~2+OSA step feed device after the device starts to realize the normal operation of the process, the main water ratio, hydraulic retention time, sludge reflux ratio and nitrification liquid reflux ratio and other parameters were optimized, the water distribution ratio of 5:5, the hydraulic retention time in 8.5H, sludge reflux ratio is 75%,reflux ratio of nitrification in 250%, COD, NH3-N, TN of the system, the removal rate of TP can reach above 90%, 94%, 76.29%, 94.95%, in accordance with the "urban sewage effluent concentration treatment plant pollutant discharge standard" level A standard, the modified A~2+OSA step feed process to determine the optimal operating parameters.In this paper, the research object of the artificial water distribution was investigated.The removal efficiency of main pollutants was investigated by the improved A~2+OSA step feed process, and the main operating parameters were optimized. The raw water is allocated to anaerobic tank and anoxic tank according to a certain proportion of the raw water. The anaerobic tank and anoxic tank water enter the aerobic pool at the same time.A part of the water outlet of the aerobic pool enters a sedimentation tank, and a part of the water pool is returned to the anoxic tank. After the mixed liquid is separated in the sedimentation tank, the sludge is fed into the sludge reduction tank, and the reflux sludge is reduced to the anaerobic tank. In the process of reducing the sludge reduction,the conventional water quality indexes were measured and analyzed, and the operation effect of the improved A~2+OSA process was compared with that of the improved A~2/O process equipment.In this study the proportion of water allocation factors, are located2:8、5:5、3:7 to study the impact of this factor A~2+OSA step feed process, the results showed that the water distribution ratio of COD and NH3-N little impact, TN removal and anoxic water was directly proportional to increase in the proportion, but with TP removal will reduce the raw water into the anaerobic tank is reduced. Therefore, in order to meet the nitrogen and phosphorus removal requirements, reasonable water distribution ratio is 5:5.By changing the system inside and outside the reflux ratio found in the sludge reflux ratio and nitrification liquid reflux ratio of 100% were taken and 200%, themodified A~2+OSA step feed nitrogen and phosphorus removal process works best for COD,TN and TP average removal rate can reach 92.31%, 70% and 90%; the removal of NH3-N were more than 95%, the effluent COD, NH3-N, TN and TP were average concentration of 42.13 mg/L, 1.83 mg/L,13.13 mg/L and 0.4 mg/L.When the hydraulic retention time to the minimum, when about 6.56 h, then the process of TN removal rate is about 72.06%, TP removal rate fell to 54.52%; when HRT was adjusted to 8.5h, the system of TN removal rate reached 75.15%, average effluent concentration of 13.98 mg/L; sequencing batch tests were adding filler to further study in this process the reactor sludge nitrification and denitrification performance to better understand the process of denitrification performance, It was found by the biofilm on the packing serving to strengthen denitrification, denitrification sludge within the system to good effect. Meanwhile, the effect of nitrogen in various biological changes along the section of the system, the system provides a theoretical basis for better optimization improvements. |
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