The inclined tube sedimentation tank is an efficient sedimentation equipment designed based on shallow tank theory, widely used in the field of water treatment. The core principle is to divide the sedimentation area into multiple shallow sedimentation units by setting inclined parallel pipes or inclined plates in the sedimentation tank, thereby significantly improving sedimentation efficiency.
1、 Working principle
（1）The core of the inclined tube sedimentation tank is the shallow tank sedimentation theory. When the effective volume of the sedimentation tank is constant, increasing the sedimentation area or reducing the tank depth can significantly shorten the settling distance of particles, thereby improving the sedimentation efficiency. The specific principle is as follows:
（2）Shallow sedimentation: The inclined tube divides the sedimentation tank into multiple shallow units, with each unit having a depth much smaller than traditional sedimentation tanks, shortening the particle settling distance and reducing settling time.
（3）Laminar flow effect: The water flow inside the inclined tube tends towards laminar flow, with a decrease in Reynolds number and an increase in Froude number, enhancing the stability of the water flow and facilitating particle settling.
（4）Gravity separation: Suspended particles settle on the surface of the inclined tube and slide down along the inclined tube to the bottom of the pool, while clear water rises through the inclined tube to the outlet area.
2、 Structural characteristics
The inclined tube sedimentation tank mainly consists of the following parts:
（1）Diagonal pipe or inclined plate: It is usually made of lightweight materials such as plastic and fiberglass. The inclined pipe is at a 60 ° angle to the horizontal plane, and the spacing or aperture between the inclined pipes is generally 80-100mm.
（2）Inlet water distribution area: Ensure even distribution of water flow and avoid short flow phenomena.
（3）Sedimentation zone: The area filled with inclined pipes or inclined plates is the main site for particle sedimentation.
（4）Clear water outlet area: located above the inclined pipe, collecting clear water through a collection device.
（5）Sludge area: located at the bottom of the tank, collecting settled sludge and discharging it through a sludge discharge device.
3、 Application scenarios
The inclined tube sedimentation tank is suitable for the following fields:
（1）Municipal sewage treatment: used for pre-treatment or deep treatment of urban domestic sewage, removing suspended solids and particulate matter.
（2）Industrial wastewater treatment: widely used in industries such as electroplating, printing and dyeing, chemical industry, mining, etc., to treat high concentration suspended solids wastewater.
（3）Water treatment: As a pre-treatment equipment for water plants, it removes suspended solids and algae from raw water.
（4）Cooling water treatment: used for bypass treatment of circulating cooling water systems to remove suspended solids and sediments from water.
4、 Advantages analysis
Advantages
（1）High sedimentation efficiency: The sedimentation efficiency of the inclined tube sedimentation tank is 3-5 times higher than that of the traditional horizontal flow sedimentation tank, and can remove more than 90% of suspended solids.
（2）Small footprint: Due to high sedimentation efficiency, the footprint of the inclined tube sedimentation tank is only 1/4 to 1/3 of that of the horizontal sedimentation tank.
（3）Short residence time: The settling time of particles is shortened, and the hydraulic retention time is generally 30-60 minutes, which is much lower than traditional sedimentation tanks.
（4）Strong impact resistance: The inclined tube sedimentation tank has a strong adaptability to changes in water quantity and quality, and operates stably.
5、 Design parameters and key operating points
（1）The length of the inclined pipe is generally 1.0-1.2m. If it is too short, it will affect the sedimentation efficiency, while if it is too long, it will increase the cost and installation difficulty.
（2）Tilt angle of inclined pipe: usually 60 °. If the tilt angle is too small, it will cause the sludge to slide smoothly, and if the tilt angle is too large, the length of the inclined pipe will be increased.
（3）Surface load: generally 5-10m ³/(m ² · h), the specific value needs to be determined according to the inlet water quality and treatment requirements.
（4）Sludge discharge method: Mechanical sludge discharge or gravity sludge discharge can be used. Mechanical sludge discharge has a better effect, but the equipment is complex; Gravity sludge discharge is simple, but requires regular cleaning.
6、 Summary
The inclined tube sedimentation tank is an efficient and compact water treatment equipment, suitable for situations that require high sedimentation efficiency. Its core advantage lies in significantly improving sedimentation efficiency through shallow pool theory, while reducing land occupation. However, issues such as easy blockage, high cost, and complex maintenance of inclined pipes also need to be taken seriously in design and management. In practical applications, it is necessary to select the parameters and operating mode of the inclined tube sedimentation tank reasonably based on the inlet water quality, treatment requirements, and site conditions to ensure its long-term stable operation.