Study On The Nitric Oxide Removal In Rdb Cooperated With Edta Complexing And The Microbial Community Structure

Nitrogen oxides(NOx) are major atmospheric pollutants.Traditional technologies for NOx removal have some drawbacks such as high costs, secondary pollution and difficulty in maintenance.Biofilter is a widely adopted method for air pollution control due to its security and lower operating costs.Rotating drum biofilter(RDB) has been highly concerned overseas in VOC_s control,demonstrating good performance.Nevertheless, little was reported on nitric oxide(NO) removal with RDB.In this thesis,denitrificaion purification of waste gases containing NO (NO normally accounted for more than 95%of the NOx) was preliminarily investigated in RDB based on the original research.By adding EDTA (Ethylene Diamine Tetraacetic Acid,EDTA) to enhance the mass transfer rate of NO,thereby the process conditions of the RDB will be optimizing. The microbial structural changes in RDB will be researched,the transformation process of NO in RDB will be explained,and then,the N balance in RDB will be described.The experimental results indicated that,when the EDTA concentration reached 500 mg/L,NO removal efficiency was increased to 99%.EBRT is a key factor influencing the denitrification process.It is reasonable to control the nutrient solution amount of 1.0～2.0 L in the experiment. Ethanol was better than glucose as external carbon source on NO removal. The optimal operating pH was 8,as well,when 500 mg/L Fe^â…¡(EDTA) was added,the optimal temperature was 47.5℃.PCR-DGGE was applied to analyze the microbial communities in RDB.The gene analysis of 16S rRNA showed that the major populations are Clostridiumsp.,β-Proteobacterium,γ-Proteobacterium and Cytopahga-Flexibacteria-Bacteroides(CFB) group Bacteroides.In addition, denitrification is related with band G25,G26 and G28.G25 is affiliated withγ-Proteobacterium.Both G26 and G28 are affiliated withβ-Proteobacterium.With the addition of Fe^â…¡(EDTA),the change of microbial community is not significant during the process.There are many different nitrogen sources in the process,including NO,NO₂,N₂,N₂O,NO₃^--N,NO₂^--N,NH₄⁺-N,biomass N,of which N₂ is the most important product.As the important intermediate product,the production of N₂O is related to pH,DO and C/N.At the end,through the analysis of N balance,the enter and exit amount of N element in gas/liquid/ biological phases balanced basically.