What is denitrification?

There are fives stages in nitrogen cycle, namely, fixation or volatilization, mineralization, nitrification, immobilization, and denitrification.  The last stage or process is called denitrification. Let's look into denitrification topic in detail. 

What is denitrification? 

Denitrification is a  facilitated process of nitrate reduction performed by a large group of heterotrophic facultative anaerobic bacteria that may ultimately produce molecular nitrogen N2 through a series of intermediate gaseous nitrogen oxide products. This respiratory process  will reduce the oxidized form of nitrogen in response to the oxidation of an electron donor such as organic matter. The preferred nitrogen electron acceptors in order of most to least thermodynamically favorable include nitrate number three  nitrite. And number two, nitric oxide  No, Nitrous oxide N2o. 

Finally, resulting in the production of the nitrogen. Where N2, completing the nitrogen cycle by denitrifying microbes require a very low oxygen concentration of less than 10% as  well as organic C4 energy, since denitrification can lower leaching of number 3 to groundwater, it can be strategically used to treat sewage or animal residues of high nitrogen content. Denitrification allows for the production of N2o, which is the green house gas that can have considerable influence on global warming. The process is performed primarily by heterotrophic bacteria such as pseudomonas. Although, autotrophic T nitrifies have also been identified. 

For example, biobacillus nitrificans with against the nitrifiers are represented in all main phylogenetic groups. Generally several species of bacteria are involved in the complete reduction of niter to molecular nitrogen and more than one in somatic pathway has been identified in the reduction process direct reduction from nitrogen to ammonium. A process known as dissimilator nitrate reduction to ammonium is also possible  for organisms that have NRF gene. This is less common than denitrification in most ecosystems as a means of nitrate reduction. Other genes known in microorganisms which denitrifying clued near nitrite reductase nitrous oxide reductase among others. Organisms identified as having these genes alcoligen xylose oxidants, many in the pseudo monas genus. Brady Rhizobium japonicum and blasto back during night. 

Denitrification work:

In waste water treatment, denitrification describes the final step of the conversion from ammonium NH4+  to nitrogen gas. After, ammonium is oxidized by microorganisms in a two-step process. Ammonium at first converted to nitrate. Nitrate is still in the waste water and although is less harmful than ammonia. It can still cause diseases. Microorganisms for denitrification are more difficult to cultivate compared to nitrifying microorganisms such as nitrosomonas or nitrobacter denitrifying are also called heterotrophic bacteria. And they require organic carbon as food as well as oxygen. Therefore, In waste water treatment applications, o certain  BOD amount has to be maintained in the anoxic Basin. This is achieved by recirculating sludge from the secondary clarifier and aerobic basin back to the anoxic basin. The heterotrophic bacteria  try to oxidize the available BOD, under the consumption of oxygen. However, as no dissolved oxygen is present in an anoxic basin, they have to look for alternative sources heterotrophic has the ability to strip the oxygen from nitrate NO3-. And to concert nitrate to nitrogen gas. Nitrogen gas floats then as bubbles to the water surface and into the atmosphere. 

The activated sludge process usually separates the anoxic basin from the aerobic basin either by building two different tanks or by creating different zones within one basin with controlled aeration or by on off Operation of aerators. It was found that under certain conditions, micro anoxic zones can be formed inside bacterial layers. This effect which is also known as simultaneously nitrification/denitrification which is especially benefitted in submerged fixed bed reactors. So here, microorganisms are attached to the film media surface and form a biofilm layer while the top layers of microorganisms consume the available oxygen to oxidize ammonia.