1. IV. Wastewater Treatment Topic IV. 3
IV. Wastewater Treatment Topic IV. 3. Ammonification, Nitrification and Denitrification. Cycle of Nitrogen in the Nature
Ammonification
Definition: Anaerobic processes of proteins and carbamide - CO(NH2)2
decomposition resulting in generation of ammonium salts and ammonia as
end-products.
First faze - carbamide hydrolyses
Second faze - ammonification

2. Nitrification
Definition: Aerobic processes leading to decomposition of ammonium salts
to nitrites and finally to nitrates (salts of the nitric acid) as end-products.
First faze - performed by specific hemotrophic bacteria specie - Nitrosomonas
Second faze - performed by specific autotrophic bacteria specie - Nitrobacter
Autotrophes utilise the energy, released in ammonum oxidation for cells mass building, delivering the necessary carbon out from CO2 in the air. In this way cycles of C and N transformations interact in the Nature. Dissolved organic substances strongly inhibit the autotrophes.

3. Denitrification
Definition: Anaerobic processes leading to N2 as end-product in a result of carbon assimilation by oxidation of organic substances with as electrons acceptor.
Processes of denitrification are due to activities of heterotrophic facultative bacteria species, such as Pseudomonas and some other facultatives
Dissolved oxygen is a strong inhibitor for the processes of denitrification
In the processes of denitrification less oxygen is utilize than the one, incorporated into the nitrates in the processes of nitrification
Nitrogen-gas release in the atmosphere, further on is fixed in the soil by specific bacteria (N-fixators) and is utilized by plants. In this way the cycle of N in the Nature is closed

4. Cycle of Nitrogen in the Nature