Transcript No Slide Title

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
CO( NH 2 ) 2  H 2O  ( NH 4 ) 2 CO3
 Second faze - ammonification
( NH 4 ) 2 CO3  2NH 3  CO2  H 2O
1
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
2NH 4  3O2  2NO2  2H 2O  4H   heat
 Second faze - performed by specific autotrophic bacteria specie Nitrobacter
2NO2  O2  2NO3  heat
 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.
2
Denitrification
Definition: Anaerobic processes leading to N2 as end-product in a
result of carbon assimilation by oxidation of organic substances

with NO3 as electrons acceptor.
5C6 H12 O6  24KNO3  24KHCO3  6CO2  12N 2  18H 2O
 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
3
this way the cycle of N in the Nature is closed
Cycle of Nitrogen in the Nature
metabolism
Plants' proteins
fixing
dead
food
N2
Nitrogen
ammonification
NH3
compounds
Carbamide
NO3-
hydrolises
II faze
nitrification
I faze
nitrification
food
Animals' proteins
metabolism
dead
NO2-
denitrification
4