Commonly used methods of domestic sewage treatment

Physical Treatment Method: a wastewater treatment method that separates and recovers insoluble suspended pollutants (including oil film and oil droplets) in wastewater through physical action. It can be divided into gravity separation method, centrifugal separation method and sieve retention method. The treatment method based on the principle of heat exchange also belongs to the physical treatment method.

Chemical Treatment Method: a wastewater treatment method that separates and removes dissolved and colloidal pollutants in wastewater or converts them into harmless substances through chemical reactions and mass transfer. In the chemical treatment method, the treatment units based on chemical reaction by adding chemicals are: coagulation, neutralization, redox, etc.; while the treatment units based on mass transfer are: extraction, stripping, stripping , adsorption, ion exchange, electrodialysis and reverse osmosis, etc. The latter two processing units are collectively referred to as membrane separation technology. Among them, the treatment unit that uses mass transfer has both chemical effects and physical effects related to it, so it can also be separated from chemical treatment methods and become another type of treatment method, which is called physical and chemical methods.

Biological Treatment Method: Through the metabolism of microorganisms, the organic pollutants in the wastewater in the state of solution, colloid and fine suspension are converted into stable and harmless substances. According to the different microorganisms, biological treatment methods can be divided into two types: aerobic biological treatment and anaerobic biological treatment. The aerobic biological treatment method is widely used in the biological treatment of wastewater. Traditionally, the aerobic biological treatment method is divided into two categories: activated sludge method and biofilm method. The activated sludge process is itself a treatment unit, and it operates in a variety of ways. The processing equipment belonging to the biofilm method includes biological filters, biological turntables, biological contact oxidation tanks and biological fluidized beds. Biological oxidation pond method is also called natural biological treatment method.

Anaerobic Biological Treatment, also known as biological reduction treatment, is mainly used to treat high-concentration organic wastewater and sludge. The processing equipment used is mainly a digester. Biological contact oxidation method: The biological contact oxidation method is used to treat wastewater, that is, the biological contact oxidation process is used to fill the filler in the biological reaction tank, and the oxygenated sewage immerses all the filler, and flows through the filler at a certain flow rate. The filler is covered with biofilm, and the sewage is in extensive contact with the biofilm. Under the action of the metabolism of microorganisms on the biofilm, the organic pollutants in the sewage are removed and the sewage is purified. Finally, the treated wastewater is discharged into the biological contact oxidation treatment system and mixed with domestic sewage for treatment, and then discharged up to the standard after chlorine disinfection.

The biological contact oxidation method is a biofilm process between the activated sludge method and the biological filter. In order to ensure that the sewage is in full contact with the filler immersed in the sewage, and to avoid the defect of uneven contact between the sewage and the filler in the biological contact oxidation tank, this aeration device is called blast aeration.

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