How to treat sewage in sewage treatment plant

It mainly removes suspended solid pollutants from sewage, and most physical treatment methods can only meet the requirements of primary treatment. After primary treatment, BOD can generally be removed by about 30%, which can not meet the discharge standard. Primary treatment belongs to the pretreatment of secondary treatment.

2. Secondary treatment

It mainly removes colloid and dissolved organic pollutants (BOD, COD) in sewage, and the removal rate can reach above 90%, which makes the organic pollutants meet the discharge standard, and the removal rate of suspended solids can reach 95%, with good effluent effect.

3. Three-stage treatment

Further treatment of refractory organic matter, nitrogen and phosphorus and other soluble inorganic substances that can lead to eutrophication of water body. The main methods include biological nitrogen and phosphorus removal, coagulation and sedimentation, sand filtration, activated carbon adsorption, ion exchange and electrodialysis.

Extended data

The selection of sewage treatment stations is an integral part of the overall planning of cities and industrial areas. The site selection is closely related to the layout of drainage pipes in cities and industrial areas and the outlet of treated sewage. In-depth investigation and technical and economic comparison should be conducted, and the following principles should be considered:

1, and the site must be located downstream of the water supply source; If the town, industrial area and living area are located near the river, the site must be located downstream, downwind of the main wind direction in summer, and keep a certain distance from the town, industrial area, living area and rural residential area, but not too far, so as not to increase the pipeline length.

2. The site should be as close as possible to the main destination of treated wastewater (such as irrigated farmland) or the receiving water body.

3. Make full use of the terrain, select areas with appropriate slopes, meet the needs of the vertical layout of sewage treatment structures and equipment, and save energy and electricity.

4. Try to occupy and not occupy farmland as little as possible, and consider the possibility of subsequent construction and development.

Baidu encyclopedia-sewage treatment plant