The sewage treatment plant construction log (1) refers to some measures or methods taken to make the sewage reach a certain set standard after it is treated by certain methods and discharged into the water body, discharged into the water body or reused.
Modern sewage treatment technology can be divided into primary, secondary and tertiary treatment according to the degree of treatment. ? Primary treatment mainly removes suspended solid pollutants from sewage, and most physical treatment methods can only meet the requirements of primary treatment. After primary treatment, BOD can generally be removed by about 30%, which can not meet the discharge standard. Primary treatment belongs to the pretreatment of secondary treatment.
The secondary treatment mainly removes colloid and dissolved organic pollutants (BOD, COD) in sewage, and the removal rate can reach over 90%, so that the organic pollutants can meet the discharge standards.
Tertiary treatment, further treatment of refractory organic matter, soluble inorganic matter such as nitrogen and phosphorus that can lead to eutrophication of water body. The main methods include biological nitrogen and phosphorus removal, coagulation and sedimentation, sand ratio, activated carbon adsorption, ion exchange, electrodialysis and so on.
The whole process is as follows: the raw sewage after coarse grid removal is lifted by the sewage lifting pump, and then enters the grit chamber, and the sewage after sand-water separation enters the primary sedimentation chamber, which is the primary treatment (that is, physical treatment). The effluent from the primary sedimentation tank enters biological treatment equipment, including activated sludge method and biofilm method. (The reactors of activated sludge process include aeration tank and oxidation ditch, etc. ), biofilm method includes biological filter, biological turntable, biological contact oxidation method and biological fluidized bed). The effluent from biological treatment equipment enters the secondary sedimentation tank, and the effluent from the secondary sedimentation tank is discharged after disinfection or enters the tertiary treatment. The primary treatment ends here as secondary treatment, and the tertiary treatment includes biological nitrogen and phosphorus removal, coagulation and precipitation, sand filtration, activated carbon adsorption, ion exchange and electrodialysis. Part of the sludge in the secondary sedimentation tank flows back to the primary sedimentation tank or biological treatment equipment, and part of it enters the sludge concentration tank and then enters the sludge digestion tank. After dehydration and drying equipment, the sludge is finally utilized.
Construction Log of Sewage Treatment Plant (2) This ten-day study in Huizhou No.7 Sewage Treatment Plant has taught me a lot, not only because ten days is enough, but also because we have a comprehensive and detailed understanding of the process flow, experiment and central control, and have a certain understanding of the software and hardware equipment of the sewage treatment plant. First of all, to understand a sewage treatment plant, we should start with its treatment process. The seventh sewage treatment plant in Huizhou City adopts SBR process (commonly known as sequencing batch activated sludge process), and the specific process flow is: water inlet → lifting pump house → coarse and fine grid → cyclone grit chamber →SBR tank → ultraviolet disinfection tank → water outlet, and the sludge generated in the whole process is concentrated in sludge tank for sludge dehydration and transportation.
In the inflow stage, detection instruments are installed to detect the contents of heavy metals such as COD and BOD in the inflow water, and these data can be timely reflected to the central control room for timely monitoring and timely response to various indicators such as water quality and metal content exceeding the standard. The lifting pump house will raise the water level to a long-term water level, and then the larger floating objects in the water will be removed through the thick and thin grids. Then, in the cyclone grit chamber, the sewage generates centrifugal force through cyclone motion to remove the suspended fine sand in the sewage to ensure the subsequent process.
SBR pool is the key to the treatment process of the seventh sewage treatment plant. There are six sewage tanks, and each tank has five processes in a treatment cycle, including water intake, reaction, sedimentation, drainage and standby. Firstly, water is fed to receive sewage, and when the water level meets the requirements, aeration is carried out. This time is the reaction period of sewage. During this period, the aeration time, intensity and sludge reflux can be determined according to the above water quality data to meet the requirements of effluent COD, total nitrogen and total phosphorus content. After the reaction, the solid-liquid separation of the mixed liquid can ensure a good mud-water separation effect, which is the key to control the effluent SS. After the precipitation is completed, the reactor can remove clarified water or discharge excess sludge from the reaction tank. After the drainage period is over, the reaction tank will enter the standby state, waiting for the next round of reaction. At this stage, in order to avoid the corruption of sludge, slight aeration should be carried out. In this way, the six ponds alternately complete the sewage treatment task at each stage.
The effluent from SBR tank will enter the disinfection tank, and the last process before the sewage leaves the factory will kill the toxic microorganisms in the water and ensure the quality of the effluent.
Laboratory is also an important part of waterworks. Its main task is to collect water from the influent of the factory and the effluent of the reaction tank every two hours, and then determine the contents of COD, total nitrogen and total phosphorus the next morning. Please refer to the chemical inspection method document of the Ministry of Environmental Protection for specific experimental steps. The laboratory test data should be sent to the central control room or the factory director at the first time, and then decide whether to adjust the treatment process according to these data. The central control room is to monitor and record all kinds of data of sewage in the factory area in time, adjust the process, observe the running state of equipment in the factory area at any time, and reflect and deal with problems in time.