Sewage treatment generally includes the following three-level treatment: primary treatment removes stones, sand, fat, and grease contained in sewage through mechanical treatment, such as grilles, sedimentation, or air flotation. wait. Secondary treatment is biological treatment, in which pollutants in sewage are degraded and converted into sludge under the action of microorganisms. Tertiary treatment is the advanced treatment of wastewater, which includes the removal of nutrients and disinfection of wastewater through chlorination, ultraviolet radiation or ozone technology. Depending on the treatment objectives and water quality, some sewage treatment processes may not include all of the above processes. Mechanical treatment section The mechanical (level one) treatment section includes structures such as grilles, grit chambers, and primary sedimentation tanks, with the purpose of removing coarse particles and suspended solids. The principle of treatment is to achieve solid-liquid separation through physical methods, and remove pollutants from Separation from sewage is a commonly used sewage treatment method. Mechanical (primary) treatment is a must for all sewage treatment processes (although some processes sometimes omit the primary sedimentation tank). The typical removal rates of BOD5 and SS in the primary treatment of urban sewage are 25% and 50% respectively. In biological phosphorus and denitrification sewage treatment plants, aeration of grit chambers is generally not recommended to avoid the removal of rapidly degrading organic matter; when the water quality characteristics of raw sewage are not conducive to phosphorus and denitrification, the setting and setting of primary sedimentation The method needs to be carefully analyzed and considered based on the subsequent processes of special water quality injection to ensure and improve the incoming water quality of subsequent processes such as phosphorus removal and denitrification. Biochemical treatment of sewage. Biochemical treatment of sewage is a secondary treatment, with the main purpose of removing unsinkable suspended solids and soluble biodegradable organic matter. Its process composition is diverse and can be divided into activated sludge method, AB method, A/O method, A2/O method, SBR method, oxidation ditch method, stabilization pond method, land treatment method and other treatment methods. Currently, most urban sewage treatment plants use the activated sludge process. The principle of biological treatment is to complete the decomposition of organic matter and the synthesis of organisms through biological action, especially the action of microorganisms, and convert organic pollutants into harmless gas products (CO2), liquid products (water) and organic matter-rich products. Solid product (microbial community or biological sludge); excess biological sludge is separated from solid and liquid in the sedimentation tank and removed from the purified sewage. Tertiary treatment: Tertiary treatment is an in-depth treatment of water. Currently, not many sewage treatment plants in my country are put into practical application. It denitrifies and dephosphorizes the secondary-treated water, uses activated carbon adsorption or reverse osmosis to remove remaining pollutants in the water, and uses ozone or chlorine to disinfect and kill bacteria and viruses, and then sends the treated water into the central Waterways serve as water sources for flushing toilets, spraying streets, watering green belts, industrial water, fire protection, etc. It can be seen that the role of the sewage treatment process is only to purify the sewage and enrich the pollutants into the sludge through biodegradation and solid-liquid separation, including the primary sludge generated in the primary treatment section, The remaining activated sludge produced in the secondary treatment section and the chemical sludge produced in the tertiary treatment section. Since this sludge contains a large amount of organic matter and pathogens, and is easily putrid and smelly, it can easily cause secondary pollution, and the task of eliminating pollution has not yet been completed. The sludge must be properly disposed of through certain volume reduction, volume reduction and stabilization harmless treatment wells. The success of sludge treatment and disposal has an important impact on the sewage plant and must be taken seriously. If the sludge is not treated, it will have to be discharged with the treated effluent, and the purification effect of the sewage plant will be offset. Therefore, in the actual application process, sludge treatment in the sewage treatment process is also very critical. !--EndFragment--