Physiological characterization and identification of the NOx utilizing quotas of an autotrophic mixed population to the purification of exhaust gases

Waste gases CO and NOx can support the growth of autotrophic microorganisms. The best studied bacterial groups are the aerobic CO-oxidizing bacteria. The problems are the chemical and physical properties of CO and NOx. Such low concentrations react extremely slow under standard conditions and their solubility in water is low. Nitric oxide or, in a more precise nomenclature, nitrogen monoxide autoxidation in the aqueous phase yields nitrite and not nitrate: 4 NO + O2 + 2 H2O => 4 NO2- + 4 H+. This simple equation involves a complex chemistry with generation of intermediate, highly oxidizing species. In contrast to them NO2 reacts vastly with water to yield HNO2 and HNO3. In the gas phase the free radical nitrogen dioxide exits in equilibrium with its dimer N2O4. The dimer reacts rapidly in aqueous solution to form nitrite and nitrate. Nitrification, the oxidation of reduced nitrogen compounds and denitrification, the reductions of oxidized nitrogen compounds are two of the dominant driving forces in the microbiological nitrogen metabolism. The major recent advance has been to establish that nitric oxide is an intermediate in the denitrification pathway. The microbial and enzymatic basis of NO and N2O production and consumption is not exact clear. Both compounds are intermediates in the sequential reduction pathway of nitrate or nitrite by denitrifiers and nitrifiers, and both are consumed by this microbial group. In contrast to d...(this text has been cut automatically)