| The project is based on the AAO process that is modified by Yixing City,Jiangsu Province,the new 75,000 tons of urban sewage treatment plant.It presents a reference for the process to optimize the operation,which studied the process technology and advanced nitrogen removal mechanism on the basis of regular operation.Through the analysis of COD and TN during one year,it was found that the annual influencing water quality of the sewage treatment plant has a great influence on the seasonal variation and the periodic production of the industry,which is mainly characterized by high concentration of pollutants in winter and low concentration of pollutants in summer.Water quality fluctuations more features in spring.Increasing the concentration of sludge has a significant effect on the effluent in the winter under low temperature operating conditions.The analysis of the contribution of denitrification at room temperature and low temperature showed that the total removal of nitrogen was in the order of anoxic,pre-anoxic,post-anoxic,anaerobic and high denitrification efficiency are pre-anoxic and anoxic.Post-anoxic as a strengthening of the process of denitrification functional areas,its contribution and denitrification efficiency is obviously inadequate.According to the analysis and evaluation of process denitrification,the identification and control of the key points and key indexes of the whole process are put forward,and the utilization and distribution of carbon sources in the optimization operation are put forward to provide reference for the further improvement of the standard optimization of the sewage treatment plant.The analysis of microbial sequencing under normal and low temperatures showed that the diversity and abundance of dominant genera showed some similarity.In the phylum-level classification of the dominant species,mainly including the Proteobacteria,Bacteroidetes,Chloroflexi and so on.In the genera-level analysis,a large number of core genus have been reported,including some functional bacteria such as nitrifying bacteria,denitrifying bacteria,hydrolytic bacteria and so on.These genera have the same functional characteristics in different environments and temperatures,and have some reference significance for the identification of key genera.Three kinds of nitrifying bacteria and twenty three denitrifying bacteria were found in the denitrification microorganisms,including heterotrophic genus,autotrophic genus,and aerobic denitrifying bacteria.There are also denitrifying bacteria that have a certain effect on certain substances,such as Denitratisoma,Dechloromonas and so on.During comparision of whole process microbial community was found that some specific microorganisms have different environmental factors,such as Sphingobacteriales,Blastocatella,etc.Energy-saving optimization of the operational effect was achieved through the use of bacteria in different environmental factors in the abundance of changes in the effective control of operating conditions.At the same time for several environmental factors sensitive bacteria in the sewage treatment research also has some reference significance.Through the pilot experiment,the influencing factors such as influent distribution,multipoint reflow and HRT of the modified process were tested,and the effects of the post-hypoxia dosing carbon source and the double-anoxic enhanced denitrification were verified.The results showed that the ratio of pre-anoxic and anaerobic influent is 3:7,when the ratio of nitrate nitrogen is less than 8mg/L,the ratio of influent can be adjusted to 2: 8,the results of postanoxic influent showed that nitrate decreased and ammonia nitrogen increased,which had no effect on total nitrogen removal.The results showed that the average removal rate of nitrate nitrogen in the anoxic decreased from 74.90% to 53.21%.The reason may be to destroy the dissolved oxygen concentration in the anoxic zone,so that the heterotrophic bacteria consumes carbon sources to reduce the denitrification effect.The increase of residence time in the anoxic is helpful for the denitrification.The end of the anoxic tank may be endogenous denitrification due to the lack of carbon source,saving the carbon source.After the addition of 20mg/L acetic acid,the average concentration of total nitrogen decreased by 2.95mg/L,and the average effective utilization rate of carbon was 47.19%.When the two anoxic plus 20mg/L of acetic acid,the average concentration of TN effluent can reach 3.17 mg / L,unit tons of water costs rose to 0.08 yuan/ton,for the operation of the sewage plant to provide reference. |
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