Issues Addressed
Eliminate the direct discharge of sewage, and eliminate the “constant water flow” and backflow at the drainage outlet to the maximum extent.
Features and Advantages
The unpowered interception and backflow prevention weir gate can keep the water level constant. It can be used as an overflow control weir in the storage tank. It can ensure the storage water level of the storage tank is constant (the maximum fluctuation deviation of the water level in the tank is about ±4% ), and it can be set flexibly. The overflow water level can be adjusted with high precision through the counterweight, which effectively increases the storage volume, improves the utilization rate of the storage space of the storage tank, and reduces the operational cost of the storage tank.
The system is fully mechanically controlled, requiring no power supply, with simple structure and exquisite design. There is only the resistance of the transmission device, and the frictional resistance is small (<0.5kg). There is no trouble of valve opening and closing control, power consumption and other problems, and it is reliable and stable. It works very well against backflow during flood / high water level.
The system reacts very sensitively to the water level difference. When the water level on both sides of the weir gate is high, the water level difference only needs 0.01 meters to overcome the force of tens of kilograms (the counterweight is generally selected within 10kg). When the water level of the outer river is high, the water level difference required for opening the weir gate is mainly used to overcome the water loss of the water flowing through the weir, which is similar like the water head difference required by the electric gate.
Because of the characteristics of the unpowered interception and backflow prevention weir door, the floating impurities will gather at the maximum water level of the interception well, about 5mm away from the weir door, and will not be discharged with the sewage discharge.
Application (Where & How)
According to the "Implementation Plan for the Elimination of Sub-Class V Water Bodies and the Renovation of Tributaries into the River in Pukou District" issued by the Pukou District Government of Nanjing City, the rivers within the Chengnan River Basin must reach Class V. The Dongfanghong River is a primary tributary of the Chengnan River and is included in the scope of the river improvement project. The Dongfanghong River (Pukou section) has a total length of 1.8km with width of about 30m.
In order to achieve the main runoff pollution control, collect the initial rainwater and dry-day mixed sewage along the Yingjiang Road section (Kanghua Road-Guangming Road), solve the existing sewage and diffused pollution , the initial rain storage tank have been built. The Dongfanghong River storage tank is located in Dongfanghong River Binhe Park in Pukou District. The net dimensions of the storage tank is 40.5m in length and 10m in width with effective storage volume of 2000 m3.
Dongfanghong River discharge interception well adopts unpowered interception and anti-backflow weir gate. The weir gate is automatically closed on sunny days, and the weir gate is automatically opened by the pressure difference of the water level in rainy weather to prevent the river from backflowing when the water level of the river rises. The weir gate does not require signal and electric control, which simplifies the system control. It can be sealed on all sides without overflow. And there is no need to set up an overflow, the anti-backflow performance is good, and it is completely dependent on hydraulic control, and there is no risk of water retention.
Comments on the Solution
The use of unpowered weir gate at the interception well can not only effectively avoid the defects of traditional anti-backflow equipment, but also realize the function of interception wells to intercept sewage, eliminate direct drainage of sewage in dry days, reduce overflow in rainy days, and reduce the operating water level of the system. At the same time, it can achieve multiple goals such as adjusting the volume and quality of sewage, reducing the impact of load on the sewage treatment plant, improving the efficiency of sewage treatment, and reducing the pressure on the urban drainage pipe network. A few days ago, the Jiangsu Provincial Department of Ecology and Environment announced the ranking of Jiangsu counties (cities, districts) in terms of surface water environmental quality and degree of improvement from January to December 2020, and Pukou District ranked first in the province.
