The phrase which has been taken out in heading, is schematical, but in fact is true — danger of pollution of water proceeds mainly from organic connections. To split them on simple chemical components, having turned in inorganic to (mineralize), it is possible by means of uglevodorodokislyayushchy bacteria which are loaded into capacity in the form of the weighed active silt (the deposit consisting of weighed particles, not detained by primary settler, and adsorbed colloidal substances) or biofilms (a colony usual which is formed on a surface of contents bio or the aero filter). Silt has property to swell, emerge on a surface finally fermentations, to a biofilm it is not typical. It develops quicker, and in case of drying of loading does not spoil and even keeps the activity. Thus, it is steadier against "stresses", is not afraid neither sharp growth of percentage of inhabitants of a colony, nor decrease in concentration of oxygen.
During reaction the energy suitable for activity of bacteria is released, on it their mass shred, properly, volume of working substance grows. Finally there is a bio cleaning of drains: aerobic or anaerobny. Microorganisms aerobes which live participate in the first case and breed during oxidation reaction, on another speaking, in the presence of oxygen. In the 2nd — opposite, at its absence: anaerobny "bacilli" are capable to exist, being fed with splitting organic and inorganic a component. Both methods approach as for natural aspect, and artificially made. Quite often anaerobny process is preliminary, after it sewage passes a phase of a final aerobic filtration.
Habitat of all participating bacteria — the biofilter. In the tank with a double bottom (distance between partitions — 0,5 m), filled with an adsorbing material like rubble, also arise a bio film. The thickness of this layer — to 2 m Aerofiltr differs from listed above a design that the working layer in it is more impressive than time in two and there is a compulsory ventilation. Its capacity — about 5 CBM of already applicable water a day on 1 CBM of volume of a tank. This or that version of the filter simply "immerse" in flowing capacity of a clearing construction and pass a liquid waste through loading.
The described operation is ecologically safe, universal (is suitable for all types of drains), is simple and with comfort in operation (regeneration of bacteria occurs at the expense of the energy received finally of oxidation of organic chemistry), it is economic. Efficiency of filtering makes 80–99 % is dependent on a type of junk. This way mainly is suitable for the sewage containing nitrogen, phosphorus and the potassium, necessary for activity of bacteria. In a number of various cases these elements in the form of consistences of salts even add in advance to dirty water. But here with the weighed rigid particles, pitches and oils usual not to consult — the filtration by means of lattices, peskolovka, settlers is required.