Product Details

The A/O sewage treatment device is mainly used for treating domestic sewage and industrial organic wastewater.
The integrated anoxic/oxic (A/O) sewage treatment device combines an anaerobic tank, an anoxic tank, an aerobic tank, a sedimentation tank, a disinfection tank, and a sludge tank. It is a high-efficiency sewage treatment equipment that integrates the removal of BOD5, COD, and NH3-N. It effectively combines the contact oxidation method with the activated sludge method, giving full play to the advantages of the two methods and overcoming their disadvantages, further improving the level of sewage treatment.

Working Principle

A/O is the abbreviation of Anoxic/Oxic. Its advantage is that it can not only degrade organic pollutants but also has a certain function of nitrogen and phosphorus removal. Anaerobic hydrolysis technology is used as the pretreatment of activated sludge, so the A/O method is an improved activated sludge method.

The A/O process connects the front anoxic section and the rear aerobic section in series. The DO in section A is not greater than 0.2mg/L, and the DO in section O is 2-4mg/L. In the anoxic section, heterotrophic bacteria hydrolyze suspended pollutants in the sewage, such as starch, fiber, carbohydrates, and soluble organic matter, into organic acids, breaking down large-molecule organic substances into small-molecule organic substances and converting insoluble organic substances into soluble organic substances. When these products are hydrolyzed under anoxic conditions and then enter the aerobic tank for aerobic treatment, the biodegradability of the sewage and the utilization efficiency of oxygen can be improved. In the anoxic section, heterotrophic bacteria ammonify pollutants in the sewage, such as proteins and fats (N on the organic chain or amino acids in amino acids), into free ammonia (NH3, NH4+). Under sufficient oxygen supply conditions, the nitrification of autotrophic bacteria oxidizes NH3-N (NH4+) into NO3-. Through reflux control, it is returned to tank A. Under anoxic conditions, the denitrification of heterotrophic bacteria reduces NO3- to molecular nitrogen (N2), completing the cycle of C, N, and O in the ecosystem and achieving harmless treatment of sewage.

Process Characteristics

Before the anoxic tank, the organic carbon in the sewage can be utilized by denitrifying bacteria, which can reduce the organic load of the subsequent aerobic tank. The reduction caused by denitrification can compensate for the demand for alkalinity in the nitrification of the aerobic tank.
After the anoxic tank, the aerobic treatment can further remove the residual organic pollutants from denitrification, improving the effluent water quality.
The removal rate of BOD5 can reach more than 90-95%, but the effect of nitrogen and phosphorus removal is slightly poor. The nitrogen removal efficiency is 70-80%, and the phosphorus removal efficiency is only 20-30%. However, due to the simplicity and prominent characteristics of the A/O process, it is still widely used at present. This process can also combine the anoxic tank and the aerobic tank into one, with a baffle in the middle, reducing the project cost and being beneficial to the renovation of existing push-flow aeration tanks.

Applications

Municipal sewage treatment

Residential sewage treatment
Sewage treatment plants.