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Nitric oxide (NO) and nitrogen dioxide (NO2) are both important Green house gases, which also cause air pollution. Industrial flue gas emissions are responsible for 17% of NOx/SOx released into the atmosphere. Treatment of flue gas to remove NO and NO2 had started a few decades ago and several chemical and biological processes have been developed to remove NOx from the flue gas BioDeNOx is a biological NOx removal process in which microbial communities are used for the reduction of NO to N2 at elevated temperatures (50 to 55 °C). Many microbiologists and process engineers have tried to use pure or co-cultures of bacteria for this purpose, however so far mixed cultures have not been studied extensively. Recently, the BioDeNOx-process has been proposed and developed for the removal of NO from flue gas by Buisman et al. (1999). In this process the NOx is absorbed in a Fe(II)EDTA2- solution followed by microbial denitrification of the NO in Nitrosyl complex (Fe(II)EDTA.NO2-) to N2. This thesis deals with the microbiology of the BioDeNox process. The diversity, identity and activity of the microorganisms performing the above-mentioned reactions are described. This was achieved by the isolation and characterization of the microorganisms, and by using culture-independent molecular tools for the identification and quantification of unculturable microorganisms. In addition, the relationship between diversity and activity in the BioDeNOx process was studied by operating a labscale reactor in which simultaneous Fe(II)EDTA.NO2- reduction and Fe(III)EDTA- reduction were taking place. |
