微生物法净化烟气中NO的机理

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

为搞清微生物法净化烟气中NO的机理,采集脱氮塔生物膜高效功能菌群样品,建立16S rRNA基因、nxrA功能基因各自相应的克隆文库,研究脱氮塔脱氮效率最高时微生物的群落结构及功能特征。结果表明:具有反硝化作用的异养菌较具有硝化作用的自养菌在数量和种类上均占绝对优势,但其在功能上却达到了一定程度的动态平衡,出现循环液中NO-3浓度范围基本稳定的状态。反硝化菌造成了体系中的N素损失,使循环液中NO-3不被大量累积。硝化杆菌属的Nitrobactor winogradskyi与Nitrobacter alkalicus等细菌发生了将NO氧化为NO-2,NO-3的硝化作用;变形菌门β亚群(Betaproteobacteria)、变形菌门γ亚群(Gammaproteobacteria)、厚壁菌门(Firmicutes)等微生物发生了将NO-2,NO-3还原为N2或N2O的反硝化作用。

Abstract：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 NO~ and microbial community. Also, its functional characteristics were investigated. The results demonstrate that the heterotrophic denitrification bacterium is a predominant group compared with autotrophic nitrifica- tion 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. Nitrobaetor winogradskyi and Nitrobacter alkalicus belonging to Nitrobacter are responsible for nitrification and the oxidization of NO to NO2 and NOx. The Betaproteobacteria, Gammaproteobacteria, and Firmicutes are mainly responsible for denitrification and reduction of NO,NO2,and NO3- to N2 or N2O. Key words：microbial purification mechanism of NO; 16S rRNA gene library; nxrA functional gene library; nitrification ; denitrifieation ; microbial community