Research on the microbial purification mechanism of NO in the coal-fired flue gas

In order to understand the microbial purification mechanism of NO in the coal-fired flue gas, the 16S rRNA gene and nxrA functional gene libraries were constructed by using biofilm sample with the highest removal rate of NOx in removal tower of NOx and microbial community. Also, its functional characteristics were investigated. The results demonstrate that the heterotrophic denitrification bacterium is a predominant group compared with autotrophic nitrification bacterium. However, their functions(denitrification and nitrification) reach a certain degree of dynamic equilibrium and result in a related stable state of NO3 - concentration in the circulating fluid. The denitrification causes the losses of N in the system and reduces the NO3 - accumulation in the circulation solution. Nitrobactor winogradskyi and Nitrobacter alkalicus belonging to Nitrobacter are responsible for nitrification and the oxidization of NO to NO2 - and NO3 -. The Betaproteobacteria, Gammaproteobacteria, and Firmicutes are mainly responsible for denitrification and reduction of NO, NO2 -, and NO3 - to N2 or N2O.