The biological treatment method of aerator in sewage treatment can be divided into aerobic method and anaerobic method according to the aerobic status of the participating microorganisms. Generally, aerobic method is more suitable for lower concentration sewage, such as ethylene plant sewage; The anaerobic method is more suitable for the treatment of sludge and sewage with higher concentration. Aerobic biological treatment can be divided into two categories: activated sludge method and biofilm method. Activated sludge method is an artificial enhancement method of self-purification of water body, and it is a method of removing organic matter in sewage relying on activated sludge main body. It is necessary for the aerobic microorganisms present in activated sludge to function in the presence of oxygen. In the aeration tank of the sewage treatment biochemical system, there is a positive correlation between the oxygenation power and the growth of aerobic microorganisms. The amount of dissolved oxygen supply should be considered according to the number of aerobic microorganisms, physiological characteristics, matrix properties and concentration. In this way, activated sludge can be in the best condition to degrade organic matter. According to the experiment, it is appropriate to maintain the dissolved oxygen in the aeration tank at 3 ~ 4mg/L. If the oxygen supply is insufficient, the activated sludge performance is poor, resulting in the reduction of wastewater treatment. To ensure adequate oxygen supply, it is necessary to rely on a device, such as an aerator.
