Basic concept of bioreactors in nitrification

Bioreactors are closed systems designed to facilitate controlled biological processes, where specific microorganisms carry out metabolic reactions to transform substances. In the context of nitrification, these devices allow the biological oxidation of ammonia to nitrite and then to nitrate, an essential process in wastewater treatment and environmental management.

Nitrification facilities based on bioreactors optimize these transformations through controlled conditions of oxygen, pH, temperature and organic load, guaranteeing high efficiency in the elimination of nitrogenous compounds. Its implementation is vital to comply with environmental regulations and reduce eutrophication in receiving water bodies.

Microorganisms involved in nitrification

Nitrification is a microbiological process in two main stages, mediated by chemoautotrophic bacteria. In the first stage, bacteria of the Nitrosomonas genus oxidize ammonia (NH3) to nitrite (NO2-). In the second, bacteria of the genus Nitrobacter convert nitrite into nitrate (NO3-). These bacteria require specific conditions for their development, such as adequate oxygen levels and a toxin-free environment.

Furthermore, the sensitivity of these microorganisms to environmental factors such as pH and temperature determines the speed and efficiency of the process. For example, the optimal pH range for nitrification is typically between 7.0 and 8.0, and ideal temperatures generally range between 25 and 35°C. Understanding these characteristics is essential for the design and operation of bioreactors.

Chemical and biochemical reactions involved

The nitrification process involves the aerobic oxidation of ammonia to nitrite and subsequently to nitrate, releasing energy that bacteria use for their metabolism. The first reaction is: NH3 + 1.5 O2 → NO2- + H+ + H2O, carried out by Nitrosomonas. The second is: NO2- + 0.5 O2 → NO3-, mediated by Nitrobacter.