Sewage treatment level:

Primary treatment: through mechanical treatment, such as grating, sedimentation or air flotation, to remove stones, sand, fat, grease, etc. contained in sewage.

Secondary treatment: biological treatment, the pollutants in the sewage are degraded and converted into sludge under the action of microorganisms.

Tertiary treatment: Advanced treatment of sewage, including removal of nutrients and disinfection of sewage by chlorination, ultraviolet radiation or ozone technology. Depending on the treatment goals and water quality, some sewage treatment processes do not include all the above-mentioned processes.

Sewage treatment process: A/O process, which uses anaerobic hydrolysis technology as the pretreatment of activated sludge, connects the front anoxic section and the rear aerobic section in series, the DO of the A section is not more than 0.2mg/L, and the O section DO=2～4mg/L, in addition to degrading organic pollutants, it also has certain denitrification and phosphorus removal functions, which is an improved activated sludge method. A2/O process is the abbreviation of anaerobic-anoxic-aerobic biological nitrogen and phosphorus removal process. Through the organic coordination of three different environmental conditions, anaerobic, anoxic, and aerobic, and different types of microbial flora, it can simultaneously remove organic matter, nitrogen, and phosphorus. The treatment efficiency of this process can generally reach: BOD5 and SS It is 90% to 95%, the total nitrogen is more than 70%, and the phosphorus is about 90%. Oxidation ditch, also known as continuous circulation aeration tank, is a variant of activated sludge process. Oxidation ditch not only has the characteristics of push flow reaction, but also has the advantage of complete mixing reaction; the former makes it have excellent conditions for water effluent, and the latter makes it have the ability to resist shock load. In the SBR process, a certain amount of activated sludge is pre-cultured and domesticated in the reactor. When the wastewater enters the reactor and is mixed and contacted with the activated sludge and there is oxygen, the microorganisms use the organic matter in the wastewater to metabolize, degrade the organic matter and make the microorganisms at the same time. Cell Proliferation. The microbial cell material is separated from the water precipitation, and the wastewater is treated. The treatment process is mainly completed by several purification processes of initial removal and adsorption, metabolism of microorganisms, formation of flocs and flocculation and sedimentation performance. CASS process, CASS biological treatment method is the abbreviation of cycle activated sludge method, CASS pool is divided into pre-reaction zone and main reaction zone. In the pre-reaction zone, microorganisms can quickly absorb most of the soluble organic matter in sewage through the rapid transfer mechanism of enzymes, and undergo a rapid accumulation process of high-load substrates, which plays a better role in the quality, quantity, pH and toxic and harmful substances of influent water. The buffering effect of the filamentous bacteria at the same time inhibits the growth of filamentous bacteria, which can effectively prevent sludge bulking; then it undergoes a lower load substrate degradation process in the main reaction zone. The CASS process integrates reaction, precipitation, drainage and functions. The degradation of pollutants is a push-flow process in time, while the microorganisms are in the periodic changes of aerobic, anoxic and anaerobic, so as to achieve the removal of pollutants. It also has good denitrification and phosphorus removal functions.