Wastewater treatment is the use of physical, chemical and biological methods of wastewater treatment, so that waste water purification, reduce pollution, and even to waste water recycling, reuse, make full use of water resources. The process of separating or contaminating the contaminants in the wastewater into harmless substances.
(Including oil film and oil beads) waste water treatment method which can be divided into gravity separation method, centrifugal separation method and screen cutting method. The principle of heat exchange is also based on the physical processing method.
Through the chemical reaction and mass transfer to separate, remove the dissolved water, colloidal state of the pollutants or to convert it into harmless matter of wastewater treatment. In the chemical treatment method, the processing unit based on the chemical reaction of the dosing agent is: coagulation, neutralization, redox, etc .; and the mass transfer-based processing unit is: extraction, stripping, stripping , Adsorption, ion exchange and electrodialysis and reverse osmosis. The latter two processing units are collectively referred to as membrane separation techniques. Which use the mass transfer of the processing unit has both a chemical effect, but also associated with the physical role, it can also be separated from the chemical treatment method, as another type of treatment, known as physical chemistry.
3. Biological treatment
Through the metabolism of microorganisms, so that the wastewater was solution, colloid and micro-suspended state of organic pollutants, into a stable, harmless material waste water treatment. According to the role of microbial differences,  biological treatment can be divided into aerobic biological treatment and anaerobic biological treatment of two types. Wastewater biological treatment is widely used in aerobic biological treatment, according to the traditional, aerobic biological treatment method is divided into two types of activated sludge and biofilm. The activated sludge process itself is a processing unit, it has a variety of operating methods. The biofilm treatment equipment is a biological filter, a biological turntable, a biological contact oxidation tank and a recently developed biofluidized bed. Biological oxidation pond law, also known as natural biological treatment. Anaerobic biological treatment, also known as biological reduction treatment, mainly used to deal with high concentrations of organic wastewater and sludge. The processing equipment used is mainly digestion tank.
4. Biological contact oxidation method
The biological contact oxidation process is used to treat the wastewater, that is, with the biological contact oxidation process in the biological reaction tank filled with filler, has been filled with oxygen filled all the filler, and a certain flow rate through the filler. In the filler covered with biofilm, sewage and biofilm wide contact, in the biofilm on the role of microbial metabolism, the sewage in the organic pollutants are removed, the sewage is purified. Finally, the treated wastewater is discharged into the biological contact oxidation treatment system and mixed with the domestic sewage treatment, chlorine disinfection after discharge. Biological contact oxidation method is a biofilm process between activated sludge method and biofilter. It is characterized by filling in the pool, filling the effluent with oxygen at the bottom of the pool, and flowing the sewage in the pool State, in order to ensure that the sewage and immersion in the sewage in full contact with the filler to avoid the existence of biological contact oxidation tank and filler contact uneven defects, this aeration device called blast aeration.