The nitrifying microorganisms belong to the chemoautotroph bacteria. They use the inorganic carbondioxide
as carbon source and ammonium is used as energy source.
The nitrification process consists of two steps. As a first step the “ammonia oxidizing bacteria” (AOB,
mainly: Nitrosomonas, in addition Nitrosospira, Nitrosococcus, Nitrosolobus and Nitrosovibrio) oxidizes the
ammonium content of the water to nitrite:
In the second step the nitrite-oxidizing bacteria (NOB, in particular:
Nitrobacter, in addition Nitrospira, Nitrospina and Nitrococcus) oxidizes the nitrite to nitrate: