Nanjing Kang Zhuo Environmental Technology Co., Ltd. (hereinafter referred to as Kang Zhuo Technology) is a manufacturer of automatic control system for sewage treatment plant. This article has introduced the process flow of sewage treatment plant automation control system in detail by Kang Zhuo Technology Electrical Engineer. Welcome to consult. At the same time, your sewage treatment plant project is looking for an automation control company, you can contact us, Kang Zhuo Technology National Unified Customer Service Hotline: 400-0940-400.
Sewage treatment refers to certain methods adopted after the water has been treated to meet certain standards and then discharged into the water body or reused. The main process of sewage treatment is: the sewage enters the plant area and passes through the 1. interceptor (according to the sewage The nature of the treatment plant allows the sewage that the plant can treat to enter the plant area) into 2. coarse grid (for salvaging larger dregs) to 3. water inlet pump house (to raise the height of sewage) to 4. fine grid (for salvaging) Small dregs) to 5. Settling pond (based on gravity separation, sedimentation and removal of inorganic particles with a larger proportion of sewage) to 6. Biochemical pond (removing BOD5, SS, and nitrogen in wastewater by activated sludge method) Or phosphorus) into 7. Final settling tank (excluding excess sludge and returning sludge) to 8. Filter cloth filter (further reducing SS to make water quality reach national standards) enter 9. UV disinfection (eliminate E. coli) and then enter 10 Water outlet (drain into external river). All of the above areas are made up of various equipment, each of which has an independent control loop or a button box set next to the equipment for easy operation by the user. The detailed description of the feasibility of automatic control is mainly based on 2-10 of the above process.
First, the coarse grille
The coarse grille mainly catches the large dregs floating with the sewage. Generally it consists of a mechanical grille and a screw conveyor. There are two automatic control methods that can be adopted. 1. Time interval control (control the grille and screw conveyor at intervals Run once after a certain time), 2. Ultrasonic level difference meter control (detect the liquid level difference before and after the grille, when the liquid level in front of the grille is higher than the liquid level after the grille by a certain value, start the grille and (Screw conveyor) Generally, the mechanical grid starts before the screw conveyor and stops before the screw conveyor, but it can also start at the same time and stop at the same time.
The coarse grid and screw conveyor are shown in Figure 1:
Second, the inlet lift pump room
The inlet lift pump room is mainly used to raise the height of sewage. Generally, in order to facilitate the external flow of sewage into the plant area, the water inlet pipeline is underground. After entering the plant area, a series of treatment processes require an automatic inflow of sewage. The pump room is used to raise the height of the sewage. In addition, the water inlet lift pump room can also control the sewage flow into the plant area. The automatic control method that can be adopted is mainly to automatically input one or two or more water pumps according to the height of the liquid level in the pump room, and each pump has a rotation start and automatic fault switching function.
The sewage lifting pump room is shown in Figure 2:
Third, fine grille
The fine grid is mainly used for salvaging the smaller dross in the sewage. Generally, the fine grid is composed of a mechanical fine grid and a screw conveyor. The automatic control method that can be adopted is the same as that of the coarse grid.
The fine grid is shown in Figure 3:
Fourth, settling pond
The sedimentation tank is mainly based on gravity separation, and the inorganic particles with a large proportion of sewage are precipitated and eliminated. The sedimentation tank is generally composed of a stirring device, a sand washing system and a sand absorption system. The sand washing system and the sand suction system cannot work at the same time. The equipment is generally operated manually. The solenoid valve installed on the pneumatic pipeline can also run automatically. Generally, the equipment in the system is started and stopped in sequence during automatic control. Users can adjust the inlet sand extraction time and the startup time of the sand-water separator according to the sand content in the water.
The grit chamber is shown in Figure 4:
V. Biochemical Pool
Biochemical tank or oxidation ditch uses activated sludge method to remove BOD5, SS and nitrogen or phosphorus in sewage. There are mainly underwater mixers, underwater thrusters, aerators and other equipment in the biochemical tanks, underwater mixers and underwater thrusters. The device is always running. The automatic control system can only monitor the running status of each device. The automatic control of the aerator generally adopts the control mode of time rotation and fault rotation.
The biochemical pool is shown in Figure 5:
Final sink pond
The final settling tank can exclude excess sludge and returning sludge. Generally, it consists of a rotary sludge scraper and a sludge return pump room. The rotary sludge scraper is generally in an always-on state and an automatic control system monitors its operating status, and the sludge returns The sludge return pump placed in the pump room can automatically control the operation according to the sludge height in the pump room. It has rotation start and fault rotation functions.
The final sinking pond is shown in Figure 6:
Seven, filter cloth filter
Filter cloth filter can further reduce SS and make the water quality meet national standards. Filter cloth filter consists of filter cloth turntable, turntable motor, flushing pump and valve. Automatic control is generally controlled by time or liquid level. The time control is to set the flushing time, the corresponding motor of the turntable motor and the operation of the flushing pump. When the liquid level is controlled, determine whether the turntable needs to be cleaned according to the water depth in the tank.
Filter cloth filter is shown in Figure 7:
Eight, ultraviolet disinfection
UV disinfection mainly removes E. coli in water. It mainly consists of UV disinfection tube, compressor and control system. The UV disinfection system is always running and has water shortage protection function. You can set the time to clean the UV disinfection tube. The internal components generate a lot of heat and are generally equipped with air conditioners. The system cannot be started without turning on the air conditioners.
Ultraviolet disinfection is shown in Figure 8:
Nine, outlet pump room
The control logic of the outlet pump room is similar to that of the inlet lift pump room. Generally, the water in the outlet pump room flows into the external river by gravity. The outlet pump room can also be controlled according to the control method of the inlet lift pump room. description.
Ten, data collection
Data collection is the main task of the automatic control system of the sewage treatment plant. The host computer system saves the data transmitted from the on-site PLC in the database. The user can view the data information of a certain period of time or convert the data into a trend chart according to his needs. The main storage indicators of sewage treatment plants are generally: influent COD, influent ammonia nitrogen, influent total phosphorus, influent PH, effluent COD, effluent ammonia nitrogen, effluent total phosphorus, effluent PH, sludge concentration at important locations, dissolved oxygen and Redox potential and so on.
The screen of the host computer of the automatic control system is shown in Figure 9: