Currently, there is a real need for rapid progress and development in almost all industries and areas of human activity [...]

Nitrogen is a chemical element commonly occurring in natural environment. Its main source is gaseous nitrogen making up to 80% of the earth's atmosphere and chemically bounded nitrogen being the component of vegetable and animal proteins. The fact that nitrogen undergoes fast and multidirectional transformations is one of its main features (Fig. 1). Such transformation occurs especially in the processes of atrophy and decomposition of organisms and the products of their metabolism (R). Ammonification results in forming of ammonia nitrogen according to the reaction [1]: R -NH 2 + HOH → R -OH + NH 3 + energy (1) Ammonia nitrogen can be assimilated by plants and microorganisms. Then, it is changed into nitrate nitrogen at favourable conditions biological decomposition is a commonly used method to remove inorganic nitrogen compounds from wastewater. Ammonia nitrogen occurring in wastewater is partly used to build new microorganism cells and part of it is removed in the gaseous form. In the initial phase nitrogen compounds are transformed to ammonia. Next, ammonia compounds are oxidized to nitrite and nitrate in aerobic conditions in the process of nitrification. In the fol-