Aerobic Granular Sludge Synergistic Nitrogen Removal Process Control And N₂O Emission Characteristics

In recent years,a large amount of nitrogen pollutants in domestic sewage and industrial wastewater,including ammonia nitrogen,nitrite nitrogen and nitrate nitrogen,have been discharged in China,which has caused the eutrophication of water bodies to become increasingly serious and endanger human health.At present,aerobic granular sludge technology,as a new type of sewage treatment technology,is one of the most valuable new biological treatment technologies,making up for the shortcomings of traditional biological treatment methods such as activated sludge method and anaerobic biological treatment.However,with China's increasingly strict wastewater discharge standards,due to the imbalance of carbon-to-nitrogen ratio and insufficient carbon source in the wastewater treatment process,it is difficult for single aerobic granular sludge and biological denitrification technology to achieve efficient nitrification reaction,subsequent denitrification reaction and The total nitrogen removal rate is up to standard,and in the process of denitrification,it will be accompanied by the release of a large amount of greenhouse gases such as nitrous oxide?N₂O?,causing many problems such as ozone layer destruction and global warming.In addition,aerobic granular sludge itself is limited by the demand for carbon sources.Many studies have used a large number of liquid carbon sources to meet the carbon sources in the process of aerobic granular sludge co-biological nitrogen removal,which will cause environmental problems such as excessive waste and secondary pollution.Therefore,based on the aerobic granular sludge technology,this thesis collaborates with other biological denitrification processes to study the N₂O release characteristics during the biological denitrification process,and determine the aerobic granular sludge collaborative denitrification process as well as the dominant bacterial groups and functions in its coupling system.The characteristics of microorganisms and microbial products provide a theoretical basis for further strengthening subsequent denitrification,achieving total inorganic nitrogen removal and improving effluent quality.The main contents and conclusions are as follows:1.Use light conditions to cooperate with aerobic granular sludge to achieve short-range nitrification.After 150 days of reactor operation,TIN removal efficiency and NAR were63.6%and 88.5%,respectively.The ratio of?SOUR?_NH4/?SOUR?_NO2 increased from 1 to 2.8,indicating that NOB activity was inhibited.The presence of algae in AGS-PSBR led to the release rate of N₂O up to 12.9?g/min.The biocommunity in AGS-PSBR showed significant difference,under the illumination of 200?mol/m²s,there was enrichment of Nitrosomonas bacteria.2.Biological denitrification is carried out in aerobic granular sludge coupled solid-phase nitrification staged reactor.In the whole stage,the effluent NH4⁺-N and TIN were as high as99.6%and 99.4%,respectively.In a cycle of AGS nitrification and PBS denitrification,the highest N₂O release rates were 12.9?g/min and 4.6?g/min,respectively.The fluorescence intensity score of component 2 is reduced from 0.66 to 0.15 in AGS-SBR and increased from0.02 to 0.05 in PBS-SBR,which indicates that proteinaceous substances may be used in the nitrification process,and nitrate or The denitrification of nitrite can stimulate the production of SMP.Microbial community analysis showed that Thauera is the main genus of AGS-SBR,while Hydrogenophaga Simplicispira and Thiomanas are the main genus of PBS-SBR.3.Integrate the coupled segmented reactor and use the additional PBS powder as carbon sources to enhance the biological denitrification in the AGS system.PA-SBR finally realized the removal of total inorganic nitrogen,and the final TIN removal rate was 98.4%.In one cycle,the concentrations of NH4⁺-N,NO2^--N and NO3^--N were all lower than 0.1,0.2 and 0.1mg/L,and the total inorganic nitrogen was removed.In one cycle,the maximum difference in N₂O release rate between PA-SBR and A-SBR was 0.8.In PA-SBR,the three-dimensional fluorescence intensity of tryptophan protein and aromatic protein substances increased from low quality a.u.to 243.4 and 400.5 a.u.,indicating sufficient PBS is consumed by AGS and SMP is not consumed as carbon sources.