Study On Denitrification Mechanism Of Partial-denitrication And Anammox Sludge And Its Application Development

Nitrogen pollution in water has become an urgent environmental problem in the world.Anaerobic Ammonia Oxidation（ANAMMOX）process has been gradually applied in sewage treatment projects due to its advantages of low cost and less energy consumption.Inmunicipal wastewater,carbon sources are limited,and short-cut denitrification is easy to achieve.The accumulation of NO₂^-provides a substrate for the anaerobic ammonium oxidation process.Therefore,the process of denitrification coupled with anaerobic ammonium oxidation（ANAMMOX）undoubtedly has a good prospect in the municipal wastewater treatment process.Anammox and denitrifying sludge were inoculated in this experiment,and UASB reactor was successfully started.Follow-up experiments were conducted to explore the accumulation of NO₂^--N and the influence of salinity in the coupling system under the conditions that the average removal rates of NO₃^--N,NH₄⁺-N and total nitrogen were 87.95%,94.53%and 91.97%,respectively.In order to investigate the impact of salinity shock on denitrifying ammonia-oxidation coupled sludge,continuous flow experiment and batch experiment were combined on the basis of stable operation of the reactor.In the long-term salinity shock experiment,when the concentration of Na Cl was less than 10g/L,the removal rates of both changed smoothly,and the average removal rates of NO₃^--N and NH₄⁺-N were both above 80%.When the concentration of Na Cl reached 30g/L,the removal rate of NH₄⁺-N decreased to 54.21%,while the average removal rate of NO₃^--N at this stage was 77.44%.In the short-term experiment of salinity shock,Na Cl could inhibit both denitrifying bacteria and Anammox bacteria,but Anammox bacteria were more sensitive to Na Cl concentration.Microbial diversity in the system decreased during reactor start-up due to laboratory acclimation.As the salinity gradient increases,the species diversity in the system decreases.In the genus property,the dominant strain is Thauera,which is in a dominant position in the competition of high salinity populations.The abundance of two kinds of Anammox bacteria,Candidatus＿Brodacia and Candidatus＿Kuenenia,fluctuates obviously with the increase of salinity.In order to explore the denitrifying bacteria and anaerobic ammonia oxidation bacteria respectively for the coupling contribution of denitrification process in the sludge.Specificity,respectively,in through the use of inhibitors of penicillin G and acetylene inhibition of heterotrophic denitrifying bacteria and anaerobic ammonia oxidation bacteria found in the experiments of the activity of isotopes,inhibition of denitrifying bacteria denitrification efficiency of reaction system significantly,denitrifying bacteria for short-range denitrifying accumulating process of NO₂^--N,bacteria is anaerobic ammonia oxidation in the system,the basis of good denitrification effect.Combined with the calculation results of denitrification contribution rate,the average denitrification contribution rate of denitrifying bacteria in the whole process was 55%,and that of anaerobic ammonium oxidation bacteria was 45%,both of which made great contributions to the efficient denitrification of the process.Under the condition of HRT=4h,C/N=3:1,the concentration of the main products was preliminarily simulated by Aquasim software.The model was verified by the measured effluent concentration in two groups of reactors with HRT=2h and HRT=3h under different conditions.HRT=2h.The quantitative analysis showed that the simulated results were ideal.Quantitative analysis:There was no significant difference between the measured and simulated values of NO₃^--N and NO₂^--N concentrations in effluent.According to the results,the measured values of the model are in good agreement with the simulated values,and the simulation results are obtained.According to the results,the measured values of the model are in good agreement with the simulated values,and the ideal simulation results are obtained.At the same time,the software was used to simulate the effluent under different C/N conditions,and the comparison of the changes in the concentration of trinitrogen effluent in the reactor reaction process showed that when the C/N was between 2.5-3.5,the short-cut denitrification accumulation of NO₂^--N was easy to occur,so as to realize the high-level denitrification of the coupled process of denitrification-anaerobic ammonium oxidation（ANAMMOX）,and the nitrogen removal rate was above 90%.