Wastewater treatment process is an economic, reasonable, scientific and effective process for urban domestic sewage and industrial wastewater. Wastewater treatment is widely used in construction, agriculture, transportation, energy, petrochemical, environmental protection, urban landscape, medical, catering and other fields. The urban wastewater treatment process shall be optimized and determined according to the treatment scale, water quality characteristics, environmental functions of the receiving water body and local actual conditions and requirements after comprehensive technical and economic comparison. The environmental protection staff of Fenglv have sorted out the process application, selection criteria and process level of wastewater treatment for everyone. As for wastewater treatment, you will understand this article!

1、 Application of wastewater treatment process

Wastewater treatment: the process of purifying wastewater to make it meet the water quality requirements for drainage of a certain water body or reuse. Wastewater treatment is widely used in construction, agriculture, transportation, energy, petrochemical, environmental protection, urban landscape, medical, catering and other fields, and more and more people are entering the daily life of ordinary people.

2、 Selection criteria

1) The urban wastewater treatment process shall be optimized and determined according to the treatment scale, water quality characteristics, environmental functions of the receiving water body and local actual conditions and requirements after comprehensive technical and economic comparison.

2) The main technical and economic indicators for process selection include: investment per unit of water treatment, reduction of investment per unit of pollutants, power consumption and cost per unit of water treatment, reduction of power consumption and cost per unit of pollutants, floor area, reliability of operation performance, ease of management and maintenance, overall environmental benefits, etc.

3) The inlet water quality of wastewater should be determined practically and the process design parameters should be optimized. The current water quality characteristics and pollutant composition of wastewater must be investigated or measured in detail to make reasonable analysis and prediction. When the water quality composition is complex or special, the dynamic test of sewage treatment process shall be carried out, and pilot study shall be carried out when necessary.

4) Actively and prudently adopt efficient and economical new processes. For the new process applied for the first time in China, it must go through pilot test and production test, and be applied after providing reliable design parameters.

3、 Wastewater treatment process level

Modern sewage treatment technology can be divided into primary, secondary and tertiary treatment according to the treatment degree.

Primary treatment is mainly used to remove suspended solid pollutants in sewage. Most physical treatment methods can only meet the requirements of primary treatment. BOD can generally remove about 30% of the sewage after primary treatment, which cannot meet the discharge standard. The primary treatment belongs to the pretreatment of secondary treatment.

Secondary treatment is mainly used to remove colloidal and dissolved organic pollutants (BOD, COD) in the sewage, with a removal rate of more than 90%, so that the organic pollutants can meet the discharge standard.

Tertiary treatment, further treatment of refractory organics, nitrogen, phosphorus and other soluble inorganic substances that can lead to eutrophication of the water body. The main methods include biological nitrogen and phosphorus removal, coagulation sedimentation, sand filtration, activated carbon adsorption, ion exchange and electroosmosis analysis.

The whole process is that the raw sewage passing through the coarse screen is lifted by the sewage lift pump, passes through the screen or sand filter, and then enters the grit chamber. The sewage passing through the sand water separation enters the primary sedimentation tank, which is for primary treatment (i.e. physical treatment). The effluent from the primary sedimentation tank enters the biological treatment equipment, including the activated sludge method and the biofilm method. The effluent from the biological treatment equipment enters the secondary sedimentation tank, The effluent from the secondary sedimentation tank is disinfected and discharged or enters the tertiary treatment. After the primary treatment, it is the secondary treatment. The tertiary treatment includes biological nitrogen and phosphorus removal, coagulation sedimentation, sand filtration, activated carbon adsorption, ion exchange and electrodialysis. Part of the sludge from the secondary sedimentation tank returns to the primary sedimentation tank or biological treatment equipment, part enters the sludge thickening tank, and then enters the sludge digestion tank. After dehydration and drying equipment, the sludge is finally used.