Denitrification oxidized nitrogen compounds

Although all oxidized nitrogen compounds that occur in wastewater can undergo denitrification, nitrate is the most important substance. The following... 

Denitrification (mediated by aerobic bacteria capable of anaerobic growth with oxidized nitrogenous compounds, also known as facultative bacteria)... 

Denitrification The reduction of oxidized nitrogen compounds (nitrate NO3, nitrite NO2 ) by denitrifying (anaerobic) bacteria. Nitrous oxide is an intermediate gaseous denitrification product. The final end product is molecular nitrogen (N2). Gases are either consumed by organisms or emitted to the atmosphere. 

The anaerobic and aerobic nitrifier denitrification pathways differ in that NO is an end product under anaerobic conditions rather than an intermediate compound. In addition, nitrogen dioxide-dependent NH3 oxidation by N. eutropha does not require ammonium monooxygenase (Schmidt et al., 2002), demonstrating that the two pathways are enzymatically different. In the absence of NH3, N. eutropha can use H2 or simple organic compounds as electron donors (Abeliovich and Vonhak, 1992 Bock et al., 1995). In contrast to the anammox process, which is strictly anaerobic, O2 does not inhibit N02-dependent NH3 oxidation and N2 production can occur even under aerobic conditions (Zart and Bock, 1998). However, Shrestha et al. (2002) observed N2 production... 

The dominant product from denitrification is N2. This process, therefore, represents a reversal of nitrogen fixation, returning fixed nitrogen from the biosphere to the pool of atmospheric N2. The release of N20 also constitutes a loss of fixed nitrogen, as the main fate of N20 in the atmosphere is photodecomposition by ultraviolet (UV) radiation with N2 and O atoms as products. The release of NO or N02, in contrast, does not lead to a loss of fixed nitrogen, because these compounds are oxidized further to HN03, which is then returned to the earth surface by wet and dry deposition. 

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