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Nitrification

2007 Schools Wikipedia Selection. Related subjects: General Chemistry;
Geology and geophysics

   Nitrification is the biological oxidation of ammonia with oxygen into
   nitrite followed by the oxidation of these nitrites into nitrates.
   Nitrification is an important step in the nitrogen cycle in soil. This
   process was discovered by the Russian microbiologist, Sergei
   Winogradsky.

   The oxidation of ammonia into nitrite, and the subsequent oxidation to
   nitrate is performed by two different bacteria ( nitrifying bacteria).
   The first step is done by bacteria of (amongst others) the genus
   Nitrosomonas and Nitrosococcus. The second step (oxidation of nitrite
   into nitrate) is (mainly) done by bacteria of the genus Nitrobacter.
   All organisms are autotrophs, which means that they take carbon dioxide
   as their carbon source for growth.

   Nitrification also plays an important role in the removal of nitrogen
   from municipal wastewater. The conventional removal is nitrification,
   followed by denitrification. The cost of this process resides mainly in
   aeration (bringing oxygen in the reactor) and the addition of an extra
   organic energy source (e.g. methanol) for the denitrification.

   In most environments both organisms are found together, yielding
   nitrate as the final product. It is possible however to design systems
   in which selectively nitrite is formed (the Sharon process).

   Together with ammonification, nitrification form a mineralisation
   process which refers to the complete decomposition of organic material,
   with the release of available nitrogen compounds. This replenishes the
   nitrogen cycle.

Chemistry

   Nitrification is a process of nitrogen compound oxidation (effectively,
   loss of electrons from the nitrogen atom to the oxygen atoms) :
    1. NH[3] + O[2] → NO[2]^− + 3H^+ + 2e^−
    2. NO[2]^− + H[2]O → NO[3]^− + 2H^+ + 2e^−

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