At the present time “Enfriho Group” Ltd. in Latvia offers BIOMAX  wastewater treatment plant, holding the test protocols issued by a notified body, which certifies the conformity of the typical wastewater treatment plants to the requirements of Latvian standard LVS EN 12566-3: 2005, accordingly the company has given right to mark its product with CE mark. Factory-built typical „Small wastewater treatment plants up to 50 GE” M5-M50 have high quality and are outlined with very high efficiency of treatment.


Basic processes of biological treatment are biological pull down of organic matter in aerobic (in presence of sufficient oxygen) and anaerobic (without oxygen) environment.

Biological treatment plants are the most suitable for treatment of domestic and municipal wastewater.

There is a great demand for them, while also constructive solutions are various, all technologies basically is built on such processes:

Ammonification – pull down of microorganism caused, nitrogen including organic matter in anaerobic or insufficient oxygen circumstances, as a result of what formed ammonium hydrate available for herbage and microorganisms; Second title of ammonification is anaerobic process – anaerobic process or zone is needed to raise separation of phosphorus. If circumstances are more anaerobic, more acetate is being produced during the process. In the same way it leads up to greater separation of phosphate. To ensure anaerobic environment in section of treatment plants, it may be without aeration system. Result of this process is gas – methane, carbon dioxide, ammonia and hydrogen sulphide, as well as intermediate products of organic matter decay. This process is used for sewage sludge treatment. Aerobic chemical processes oxidize organic matter containing carbon, nitrogen, sulphur, phosphorus, and mineral salts (carbonic acid, nitric acid, sulphuric acid and phosphoric acid) and carbonic acid.

Denitrification – degration (reduction) of oxidized nitrogen compounds and eduction of free nitrogen.

Nitrification – ammonium compounds caused by microorganisms oxidize to nitrite and nitrate in bacterium’s aerobic conditions (in presence of sufficient oxygen – at least 2 mg/l); Second title of nitrification is aerobic process – Aerobic process happens if the system (plant) is supplied with air of a pump or a compressor. In aerobic process supplied with air, a part of organic matter has been oxidized to CO2 and water, but the rest of waste-water is used for the synthesis to form a surplus of biomass, known as active sludge. Biochemical reactions leading to the removal of organic compounds characterized by the following equation: Organic matter + O2 + nutrients —> microorganisms CO2 + H2O + new cells

Ammonia is removed from the system with two groups of bacteria together called as nitrification bacteria, as they catalyze reaction of nitrification. Nitrification is a process of ammonia oxidation in which ammonia is being oxidized to nitrate in two reactions which realized different groups of aerobic bacteria.
NH3 + 1,5 O2 —> NO2 +H+ +H2O
NO2 +1,5 O2 —>NO3