Biological treatment of domestic wastewater

Effluent biotreatment facilities are open or underground ponds, filtration fields or digesters, depending on the method used. In ponds and filtration fields, organic particles dissolved in wastewater decompose during the vital activity of bacteria with an aerobic type of metabolism. At the same time, activated sludge is formed in ponds with dissolved pollutants - a suspension consisting of pollutant particles and bacteria that have grown on them. Anaerobic organisms develop in digesters, which do not require the presence of oxygen to exist.

With air or without?

Aerobic and anaerobic methods differ in their specifics. Anaerobic bacteria cope better with strong organic pollution and are characterized by a small increase in biomass. However, they do not completely decompose organic matter and after them additional waste treatment is required under aerobic conditions. Aerobic bacteria, on the other hand, decompose almost 100% of organic residues to molecular water and carbon dioxide, but they are viable and active only at relatively low concentrations of pollutants and require aeration - saturation of the substrate with oxygen. To increase the improvement of the output indicators, the treatment plant is specially populated with certain strains of bacteria. The species composition of the bacterial material is selected depending on the composition of pollutants in wastewater.

Purification of domestic wastewater

Domestic wastewater includes wastewater discharged into the sewer network from catering units, latrines, showers, laundries and similar facilities. The composition of these effluents is characterized, in addition to organic (about 58%), by a significant content of mineral pollutants (40%) and surfactants used as components of detergents. A large proportion of organic pollution is physiological excretions and organic residues from food processing. The presence of detergent components in the solution complicates the course of biological treatment processes.

Features of biotreatment

- this is one of the stages of complex cleaning, which is preceded by mechanical cleaning and followed by chemical methods to bind pollutants and destroy pathogens. Taking into account the scale of the treatment facilities and the average composition of the effluents, the optimal method of biotreatment is selected with or without additional aeration, with the return introduction of activated sludge, a counterflow system and other auxiliary means to achieve acceptable levels of treated water at the outlet.