Microorganism denitrification

Attached growth processes Wastewater treatment processes in which the microorganisms and bacteria treating the wastes are attached to the media in the reactor. The wastes being treated flow over the media. Trickling filters, bio-towers, and RBCs are attached growth reactors. These reactors can be used for removal of BOD, nitrification, and denitrification. 

Denitrification, a dissimilatory pathway of nitrate reduction (see Section 3.3 also) into nitrogen oxides, N2O, and dinitrogen, N2, is performed by a wide variety of microorganisms in the forest ecosystems. Measurable rates of N20 production have been observed in many forest soils. The values from 2.1 to 4.0 kg/ha/yr are typical for forest soils in various places of Boreal and Sub-Boreal Forest ecosystems. All in situ studies (field monitoring) of denitrification in forest soils have shown large spatial and temporal variability in response to varying soils characteristics such as acidity, temperature, moisture, oxygen, ambient nitrate and available carbon. 

Tiedje JM. 1988. Ecology of denitrification and dissimUatory nitrate reduction to ammonium. In Zehnder AJB, ed. Biology of Anaerobic Microorganisms. New York Wiley-Interscience, 179-244. 

Under field eonditions, not all intermediate products are eonverted to N. Nitrate reductase, for example, eauses a decrease in the enzymatie aetivity. Denitrifieaton in the absence of oxygen is eaused by a large number of baeteria Table 15.4 lists the main microorganisms capable of denitrification. 

Application methods may be adapted to deliver microorganisms, enzymes, nutrients, and electron donors to subsurface zones in order to stimulate or enhance denitrification. 

Tiedje, ]. M. (1988). Ecology of denitrification and dissimilatory nitrate reduction to ammonia. In Biology of Anaerobic Microorganisms (A. J. B. Zehnder, ed.). pp. 179-244. Wiley, New York. 

Ammonia is oxidized in nature to nitrate via several intermediates in the process of nitrification. Nitrate may be reduced to nitrite by either a dissimilatory or an assimilatory process. Nitrite may be assimilated into the cell via reduction to ammonia, or it may be reduced by microorganisms to N20 and N2 in denitrification. A major part of the total nitrogen in this pathway is lost to the atmosphere. However, in turn, atmospheric dinitrogen is converted to ammonia by various bacteria in nitrogen fixation. 

In 1888, Beijerinck published a series of reports entitled Die bakterien der Paplionacen-Knollchen which he called Bacillus radicicola. At about the same time (1885-1891) Bertholet, Warington and Winogradsky had isolated the main microorganisms from soil and water responsible for ammonification, nitrification and denitrification. 

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