Study On Synergistic Biological Denitrification With Wastewater And Flue Gas By Nitrification/Denitrification/Anammox Process

NO_x contained in the flue gas will not only harm human health,but also cause environmental problems such as photochemical smoke and acid rain.Biological denitration has the advantages of simple method and low energy consumption.In addition to nitrification and denitrification biological denitrification,Anammox,which can simultaneously remove ammonia nitrogen and nitrite nitrogen in sewage and has the characteristics of green energy saving,has also been found to have the ability to purify NO.Therefore,this paper intends to develop a simultaneous biological treatment of wastewater and flue gas based on nitrification,denitrification and Anammox reaction.In this study,Bio-Trickling Filter（BTF）was established.Firstly,the anaerobic activated sludge of the sewage treatment plant was inoculated for experiment,and then the Anaerobic Ammonia Oxidation bacteria（An AOB）in the laboratory was inoculated to form biofilm.The influence of influent C/N,oxygen concentration,spray liquid operation mode,intake NO_x concentration and influent NO₂^--N concentration on the removal performance of system process pollutants was studied.High-throughput sequencing was used to analyze the microbial community structure and predict the changes in molecular ecological functions.The main research results are as follows:（1）When the C/N ratio was 10:1 and the An AOB was added to SND,the effluent nitrate concentration of SNAD system decreased to 0.06 mg·L^-1,and the total nitrogen removal rate increased from 65%to 99%.However,after holiday shutdown,the effluent nitrate nitrogen increased,the C/N increased to 12:1,the effluent nitrate concentration decreased to 0.19 mg·L^-1,and the total nitrogen removal rate increased to 91.8%.In the SNAD system,the abundance of bacteria with denitrifying function increased with the increase of C/N,and the An AOB was transformed from Candidatus Brocadia to Candidatus Anammoxoglobus.（2）C/N was 10:1,5%oxygen was introduced into the system,the effluent ammonia nitrogen concentration decreased from 8.3 mg·L^-1 to 1.8 mg·L^-1,and the TN removal rate increased from 78.9%to more than 95%.The relative abundance of norank＿f＿norank＿o＿SBR1031 with nitrification function increased after 5%oxygen was introduced.（3）The C/N gradient decreased from 10:1 to 2:1,the effluent nitrate concentration increased from 0 mg·L^-1 to 49 mg·L^-1,and the total nitrogen removal rate decreased from 95%to 50%.The relative abundance of denitrifying bacteria decreased with the decrease of C/N,and the abundance of Candidatus Brocadia increased（from 10:1 to 3.3:1）,and then decreased.The abundance of KEGG pathway genes was down-regulated with the decrease of COD concentration,and up-regulated with the increase of ammonia and nitrite concentration.（4）Oxygen concentration in the system changed from 5%to 3%and sealing the mouth of the circulating spray bucket,dissolved oxygen concentration in the system decreased,effluent nitrate concentration decreased to 4 mg·L^-1,and the total nitrogen removal rate of the system increased to more than 95%.The abundance of denitrifying bacteria and An AOB Candidatus Brocadia increased with the decrease of oxygen and dissolved oxygen concentration.The relative abundance of denitrifying pathway genes in KEGG pathway was up-regulated.（5）The nitrogen removal efficiency of continuous flow（65.4%）was lower than that of sequential batching-circulating flow（92.7%）,and the Anammox and denitrification activities decreased.The relative abundance of Candidatus Brocadia and denitrifying bacteria,the only An AOB in the system,decreased.The NO_xconcentration of intake gas increased from 200 ppm to 800 ppm,the average removal rate of total nitrogen decreased from 65.4%to 62.5%.The relative abundance of denitrifying bacteria in the system decreased.The gas phase denitration rate is stable above 99%.（6）The concentration of NO₂^--N in influent decreased from 50 mg·L^-1 to 0mg·L^-1,and the total nitrogen removal rate decreased from 62.5%to 31.9%.The relative abundance of denitrifying bacteria and An AOB Candidatus Brocadia decreased in the system.The relative abundance of denitrifying related KEGG functional genes was not uniform.The gas phase denitrification rate has been maintained above 99%.