The biological contact oxidation method is one of the main facilities of the biofilm method. The biofilm method is a general term for a large category of biological treatment methods. It mainly uses microorganisms attached to the surface of certain solid objects (ie, biofilm) for organic sewage treatment method. Biofilm is an ecosystem composed of highly dense aerobic bacteria, anaerobic bacteria, facultative bacteria, fungi, protozoa, and algae. The solid medium attached to it is called filter material or carrier. From the filter material, the biofilm can be divided into the Qingqi layer, the good gas layer, the attached water layer, and the sports water layer. The principle is that the biofilm first adsorbs and adheres to the organic matter in the water layer, decomposes it by the aerobic bacteria in the aerobic layer, and then enters the anaerobic layer for anaerobic decomposition, and the flowing water layer washes away the aging biofilm to grow a new biofilm. , So back and forth in order to achieve the purpose of purifying sewage. The aging biofilms continuously fall off and are removed by precipitation as the water flows into the secondary sedimentation.

The treatment structure of the biological contact oxidation method is an immersion aerated biological filter, also called a biological contact oxidation tank. The biological contact oxidation tank is equipped with fillers, the fillers are submerged in wastewater, and biofilms grow on the fillers. During the contact between the wastewater and the biofilms, the organic matter in the water is adsorbed by microorganisms, oxidized and decomposed and converted into new biofilms. The biofilm shed from the filler is removed after flowing to the secondary sedimentation tank with the water, and the wastewater is purified. In the contact oxidation tank, the oxygen required by the microorganisms comes from the water, and the waste water is constantly replenishing the lost dissolved oxygen from the air. Air enters the water flow through a perforated cloth air pipe at the bottom of the pool. When the bubbles rise, oxygen is supplied to the waste water, and sometimes it is used to return the pool water.

The characteristics of biological contact oxidation method:

  1. Due to the large specific surface area of ​​the filler, the oxygenation conditions in the tank are good. The amount of biological solids per unit volume in the biological contact oxidation tank is higher than that in the activated sludge process aeration tank and biological filter. Therefore, the biological contact oxidation tank has a higher volume load;
  2. The biological contact oxidation method does not require sludge return, so there is no sludge expansion problem, and the operation and management are simple;
  3. Due to the large amount of biological solids and the completely mixed type of water flow, the biological contact oxidation pond has a strong ability to adapt to sudden changes in water quality and quantity;
  4. When the organic volume load of the biological contact oxidation tank is high, its F/M is kept at a low level, and the sludge output is small
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