Microbiology
The oxidation of the ammonium to nitrogen gas has been achieved with attached growth and suspended growth wastewater treatment processes. The most common bacteria responsible for the two step conversion are the autotrophic organisms, Nitrosomonas and Nitrobacter, and many different heterotrophs. The former obtain energy from the oxidation of ammonia, obtain carbon from CO2, and use oxygen as the electron acceptor. They are termed autotrophic because of their carbon source and termed aerobes because of their aerobic environment. The heterotrophic organisms are responsible for denitrification or the reduction of nitrate, NO3-, to nitrogen gas, N2. They use carbon from complex organic compounds, prefer low to zero dissolved oxygen, and use nitrate as the electron acceptor.
Read more about this topic: Simultaneous Nitrification-denitrification