Research On Small Town Wastewater Of The Microporous Aeration Oxidation Ditch Treatment Effectiveness

With the rapid development of society, the continuous expansion of urbanization to increase prominence of the public’s environmental awareness is gradually increased. Excess of nitrogen and phosphorus emissions caused eutrophication problem, cause the attention of the height of the society. Sewage plant is not appropriate of using technology. Not only denitrification and phosphorus removal effect is not ideal, but also caused a lot of waste of energy consumption. Strengthening of the sewage plant denitrification and phosphorus removal process, It is great significant.to control eutrophication and to improve water environment.Oxidation ditch has covers less area, simple process and so on. Partition aeration can form different dissolved oxygen environment, provide good denitrification and phosphorus removal for microbial conditions.Through the study of different partitions aeration, can optimize the oxidation ditch running situation, achieve the goal of energy saving.This topic on the basis of the oxidation ditch pilot plant, Through the experiment, in the depth of 0.6m, and the reflux ratio of 100%,the three division under the best conditions, and compared to each partition processing effect to get the best partition. Under the condition of optimum partition, winter running effect is studied, and take the corresponding improvement measures. After studying the macroscopic test, and microscopic study of the sewage plant of activated sludge, tested the internal changes of each index and sludge microbial population structure, compare all aspects of the oxidation ditch sewage treatment was studied. Main results as follows:The best working condition of AO partition for hydraulic retention time is 10 h, dissolved oxygen concentration is 1.5mg/L, SS、COD、NH₃-N、TN、TP water concentration respectively is 17.2mg/L、51.2mg/L、4.2mg/L、14.8mg/L、1.3mg/L, Total phosphorus effluent can be solved through chemical phosphorus removal. The best working condition of A2 O partition for hydraulic retention time is 12 h, dissolved oxygen concentration is 2.5mg/L, SS、COD、NH₃-N、TN、TP water concentration respectively is 15.5mg/L、44.2mg/L、7.3mg/L、19.7mg/L、1.8mg/L, Total phosphorus also can be solved through chemical phosphorus removal. The best working condition of three stage AO partition for hydraulic retention time is 12 h, dissolved oxygen concentration is 1.5mg/L, NH₃-N、TN、TP water concentration is 3.6mg/L, 14.3mg/L, 0.8mg/L.By comparison, three stage AO partition for each index can steady the water standard, the water is better than other partitions, so three stage AO partition as the best partition, The optimal condition of hydraulic retention time is 12 h, dissolved oxygen concentration is 1.5mg/L.The path of dissolved oxygen on the optimal partition monitoring, sampling points in the vertical direction from the surface of 0.1m, 0.5m, 0.8m,Dissolved oxygen of anaerobic zone is 0.1⁰.2mg/L, at all levels anoxic zone of dissolved oxygen is 0.4⁰.6 mg/L, all levels aerobic zone of dissolved oxygen is 1.4¹.6 mg/L. Ensure the district of anaerobic phosphorus release, nitrification and denitrification reaction.Under the optimal partition, NH₃-N、TN、TP water concentration is 3.8mg/L, 15.3mg/L, 0.8mg/L in summer. NH₃-N、TN、TP water concentration is 7.4mg/L, 18.9mg/L, 1.1mg/L in winter. The water effect is poor in winter. So the sludge concentration increased from 3000mg/L to 4000mg/L, aerobic zone dissolved oxygen increased from 1.5 mg/L to 2.0 mg/L. After transforming such measures, NH₃-N、TN、TP water concentration is 6.5mg/L, 17.2mg/L,0.8mg/L. The effect is obvious for improving and to be used for reference in sewage plant.After the macroscopic test, anoxic pool and aerobic pool sludge of oxidation ditch to be used for microenvironment and bacterial population structure research. Monitoring the DO、NH₄⁺-N、NO₃^--N、NO₂^--N in the sludge. The result is almost not changed much. The process mainly to be completed through facultative bacteria, such as Bacteroidetes、Nitrospirae and Proteobacteria. The whole process of nitrification and denitrification mechanism is denitrification for the entire way.