1. Activated sludge technology: Activated sludge technology is a biological method that introduces air into wastewater to allow aerobic microorganisms to multiply and cultivate to form activated sludge with strong adsorption capacity. Biological methods have gradually become the mainstream method of sewage treatment technology. The basic process of activated sludge technology: It consists of an aeration tank, a secondary sedimentation tank, an aeration system, and a sludge return system. The wastewater flowing out of the primary sedimentation tank and the activated sludge returning from the bottom of the secondary sedimentation tank enter the aeration tank at the same time to form a mixed liquid. Under the action of the aeration tank, the mixed liquid is fully aerated, and the activated sludge and wastewater are fully in contact. The soluble organic pollutants in the wastewater are adsorbed by the activated sludge and decomposed by the microbial community, so that the wastewater is purified.
2. A/O process: also called anaerobic aerobic process. In addition to removing organic pollutants in wastewater, it can also remove nitrogen and phosphorus at the same time. For high-concentration organic wastewater and difficult-to-degrade wastewater, a hydrolysis acidification section is set before the aerobic section to significantly improve the biodegradability of the wastewater.
3. A2/O method: The biological denitrification and phosphorus removal process is a combination of traditional activated sludge process, biological nitrification and denitrification process and biological phosphorus removal process. The treatment efficiency of this process can generally reach: BOD5 and SS are 90%~95%, total nitrogen is more than 70%, and phosphorus is about 90%. It is generally suitable for large and medium-sized urban sewage treatment plants that require denitrification and phosphorus removal. However, the capital construction cost and operating cost of the A2/O process are higher than those of the ordinary activated sludge method, and the operation and management requirements are high. Therefore, for the current national conditions in my country, this process is only used when the treated sewage is discharged into a closed water body or a slow-flowing water body to cause eutrophication, thereby affecting the water supply source.
4. Biofilter: Its biggest feature is that it integrates biological oxidation and interception of suspended solids, saving subsequent sedimentation tanks. The anaerobic hydrolysis-high-load biofilter treatment system integrates primary sedimentation tanks, aeration tanks, sludge return facilities and oxygen supply facilities, which greatly simplifies the sewage treatment process.
5. Artificial wetland: It is a method of removing or reducing pollutants in water by using the dilution and degradation of multi-level organisms in artificial water ecosystems. As a new type of ecological sewage treatment technology, artificial wetlands have many advantages, such as low investment and operating costs, strong impact load resistance, stable treatment effect, good effluent quality, and aquatic plants have certain economic value. The main subsurface artificial wetlands used for rural domestic sewage treatment are subsurface artificial wetlands.
6. Unpowered buried domestic sewage treatment device: Domestic sewage first enters the anaerobic digester, and the suspended matter in the sewage settles down to become sludge. The sludge is naturally fermented for a certain period of time, and the organic matter is degraded. The effluent water quality is stable and meets the national secondary emission standards.
7. Biofilm technology: The biofilm method is an artificial treatment technology mainly used in decentralized domestic sewage treatment, including anaerobic and aerobic biofilms. Anaerobic or aerobic microorganisms attach to the surface of the carrier to form a biofilm to adsorb and degrade pollutants in the sewage to achieve the purpose of purification. This method has simple equipment, low operating costs, and high treatment efficiency. The reactor is generally composed of three parts: filler, water distribution device and drainage system. The fillers used are inorganic and organic. At present, new biofilm reactors and immobilized microorganism technologies have also been widely studied. MBR (membrane bioreactor) technology is one of them, and it also includes biological.
8. Aerated biological filter: BAF for short, is the third generation of biological filter that combines the advantages of biofilm method and activated sludge method. BAF has the functions of removing organic matter, harmful substances, denitrification and phosphorus removal; it occupies a small area, has low infrastructure investment, and has low energy consumption and operating costs.
9. Integrated MBR process: a traditional improved process that combines the activated sludge method with the integrated submerged membrane separation system. The solid-liquid separation process using the membrane assembly replaces the traditional sedimentation process, which can effectively remove solid suspended particles and organic particles and prepare sterile water. The effluent from the system can be directly used for production or life reuse. All indicators of the effluent discharged by the treatment system can meet the specified standards of “Urban Sewage Recycling and Urban Miscellaneous Water Quality”. This technology is suitable for sewage treatment facilities with reuse requirements or limited land use, with a treatment scale of 20 to 500 tons/day. Process parameters: the residence time in the anoxic reaction zone is not less than 2 hours, the residence time in the MBR zone is not less than 4 hours, and the sludge treatment cycle is 360 days.
