Study Of Nitric Oxide Removal In Flue Gas Via Anammox Process

Compared with the traditional denitrification process,anammox process was famous for low energy consumption,low operating cost and simple process flow.At present,the most studies on anammox process are combined with partial nitrification and denitrification for full-scale application in high-ammonium wastewater and municipal sewage treatement.Nitric oxide,as intermediate of anaerobic ammonia oxidation reaction,can be alternative substrate.The purpose of this study is to explore the possibility of nitric oxide removal in flue gas by anammox process,and try to combine it with ammonium wastewater treatment.Furthermore,it could be providing an alternative method in biological NOx removal process and a complement of anammox process and application.The possibility of ammonium removal with Fe(II)EDTA-NO via anammox was explored.The Fe(II)EDTA-NO solution negatively affected the conventional nitrite-dependent anammox bacteria when the solution concentration exceeded 0.5 mM in batch tests.Fe(II)EDTA-NO-cultivated anammox bacteria removed the ammonium coupled to complex NO reduction(≤3.5 mM),the optimal removal efficiency was 85%,and the best nitrogen load was 0.092 g N/L·d.The batch test results demonstrated that Fe(II)EDTA-NO/NH4+molar ratio was approximately 0.97 and the complex NO-dependent process existed lesser nitrate than that generated by conventional anammox.Moreover,Kuenenia stuttgartiensitiensis became the dominant anammox bacteria when the biomass is cultivated using the inoculated bacteria,and the proportion increased to 67.5%for ribosomal intergenic spacer analysis and library construction.Anammox biofilters with modified non-woven biomass carriers were developed to remove NO in the gaseous phase.The NO removal rate was maintained at 40-60%in the range of 100-500 ppm,and the removal eefficiency reached 80%at 600-1000 ppm.Fe(II)EDTA was introduced to enhance NO removal efficiency.When the Fe(II)EDTA concentration increased to 0.24 mM from 0.03 mM,the NO reduction rate increased from 44.1%to 68.8%.The NO removal efficiency increased significantly with the temperature increased,37℃ was optimum.The gas liqid ratio became an outstanding operating parameter in the reactor;NO removal rate increased one times when the ratio was increased to 1000 from 50.The removal efficiency of nitric oxide was not significantly affected by inlet pH(7.0-8.0)and ammonia nitrogen concentration(50-150 mg/L).A novel AnammoxDeNOx process was designed to simultaneously remove NOx in flue gas and ammonium wastewater,which anammox biofilter combined with a complex adsorbing reactor.The RSM results showed that the optimal values of Vc and Va were 42.69 and 43.83 mL/min,and the total nitrogen removal rate was 62.68 mg N/h,NO removal efficiency was 85%.On the same condition,the results of verification experiment presented that the total nitrogen removal rate was 67.45 mg N/h,NO removal efficiency was 90.9%.The performance of the AnammoxDeNOx process indicated a NOx removal efficiency from simulated flue gas(including CO2,SO2,O2 and NO2)of 87-96%using simulated ammonium wastewater.With municipal wastewater,the removal efficiencies for NOx were 70-90%,total nitrogen were 40-70%,and COD were 70-90%(NO concentration:100-500 ppm).The anammox genus underwent considerable changes from the dominant Candidatus Kuenenia in the stage of domestication to the predominant Candidatus Brocadia,which then became the dominant species in the simulated flue gas and actual municipal wastewater stages.To further understand the difference of microbial community and nitrogen metabolic pathway in nitrte-dependent Anammox system and AnammoxDeNOx system which the substrates were simulated flue gas and municipal wastewater.Candidatus Kuenenia was the dominant bacteria and completed the nitrogen metabolism alone in nitrte-dependent Anammox system.When the simulated flue gas and municipal wastewater were introduced,the nitrogen metabolic process was completed via anammox,nitrification and partial denitrification,and Candidatus Brocadia and Candidatus Kuenenia were dominant anammox bacteria in the system.In addition,the functions related to carbon metabolism,microbial activity,anabolism,growth and reproduction were significantly increased.