At present, most domestic and foreign water treatment processes use sedimentation (clarification) filtration and disinfection forms, among which the sedimentation part is particularly important for the removal of suspended solids in raw water. As one of the main facilities for removing suspended solids in water, sedimentation tanks have been widely used in the water industry. Looking at the development of sedimentation structures, it can be found that before the 1960s, horizontal flow, vertical flow, and radial flow sedimentation tanks were mainly used. Since the 1960s, various clarification tanks have been popular for a while. After the 1970s, mainly inclined tube, inclined plate, and composite sedimentation tanks were used. The improvement of sedimentation structure form has improved the efficiency of sedimentation separation. The design and development of sedimentation tanks revolve around two aspects: increasing sedimentation area and changing water flow patterns. The design of sedimentation tanks always aims to improve their sedimentation efficiency.

1) Shortening the sedimentation distance of particles and increasing the sedimentation tank area, inclined tube sedimentation belongs to this category;

2) Increasing the settling speed of alum flower particles is achieved by using efficient flocculants and optimizing flocculation processes.

Horizontal sedimentation tank is currently the most widely used tank type in large and medium-sized water supply plants in China, with advantages such as simple structure, convenient management, and strong resistance to impact loads. The horizontal sedimentation tank is rectangular, with the upper part being the sedimentation area and the lower part being the sludge area. There is an inlet area in the front of the tank and an outlet area in the rear. After coagulation, the raw water flows into the sedimentation tank and is evenly distributed along the entire cross-section of the inlet area, entering the sedimentation area, and then slowly flowing towards the outlet area. The particles in the water settle at the bottom of the tank, and the deposited sludge is regularly discharged outside the tank.

Honeycomb inclined plate (tube) sedimentation is the placement of numerous honeycomb inclined plate (tube) components at a certain angle (usually 60 degrees) to the horizontal plane in a sedimentation tank. Water can flow from bottom to top or from top to bottom, while particles settle at the bottom and then slide down automatically. From the analysis of improving the hydraulic conditions of the sedimentation tank, due to the significant reduction in the hydraulic radius of the sedimentation tank, the Reynolds number R is greatly reduced and the Froude number is greatly increased, meeting the requirements of water flow stability and laminar flow. In order to further improve sedimentation efficiency, many improved honeycomb inclined plate (tube) sedimentation tanks have emerged.

1. Large wet perimeter and small hydraulic radius.

2. The laminar flow state is good, and particle settling is not affected by floc flow interference.

3. When the length of the inclined pipe is 1 meter, the effective load is calculated as 3-5 tons/meter 2· Time design. Control V0 within the range of 2.5-3.0 millimeters per second for optimal effluent quality.

4. When using a honeycomb inclined pipe at the water intake, with a length of 2.0-3.0 meters, it can operate safely in high turbidity with a sediment content of 50-100 kg/m3.

5. Adopting a inclined tube sedimentation tank, its processing capacity is 3-5 times that of a horizontal flow sedimentation tank, and 2-3 times that of an accelerated clarification tank and a pulse clarification tank.

Product specifications: Φ 25mm Φ 35m Φ 50mm Φ 80mm

The labyrinth type inclined plate sedimentation tank is equipped with several wing shaped blades in the vertical direction of the inclined plate of the ordinary inclined plate sedimentation tank. The wing shaped blades divide the incoming water flow into the main flow area, swirl area, and circulation area. The flocs located in the mainstream area gradually sink under the combined action of flow velocity and sedimentation rate. The flocs in the vortex zone are forcibly transported to the circulation zone, and some flocs are intercepted through each wing. The flocs entering the circulation zone move in a spiral shape under the action of the circulation and sink along the fins to the bottom of the pool. The vortex forced transport in the vortex area of the labyrinth inclined plate sedimentation tank and the efficient sedimentation in the circulation area make it have a high sedimentation efficiency.

The particle separation of labyrinth inclined plates belongs to dynamic separation, especially in the vortex zone, which includes the separation process of gravity, fluid resistance, and inertial force under the action of swirling flow. Moreover, the mass exchange generated in the mainstream and swirling zones also has the effect of causing the flocs to collide and coagulate with each other. Therefore, its treatment effect is better than that of ordinary inclined plate precipitation.

In theory, the water flow in the honeycomb inclined tube packing sedimentation tank is in a laminar state, but in reality, there is pulsation in the water flow in the inclined tube sedimentation tank. This is because when the large alum particles in the inclined tube move relative to the water during sedimentation, small vortices will be generated behind the alum particles, and the motion generated by these vortices causes pulsation in the water flow. These pulsations have no effect on large alum particles, but play a supporting role in the precipitation of small particles with incomplete reactions, thus affecting the effluent quality. In order to overcome this phenomenon and suppress the pulsation of water flow, small spacing inclined plate sedimentation equipment has emerged.

1. Due to the significant reduction in spacing, the precipitation distance of alum flowers is also significantly reduced, allowing more small particles to precipitate down;

2. Due to the decrease in spacing, the hydraulic resistance increases, making it the main part of the water flow resistance in the sedimentation tank. As a result, the flow distribution in the sedimentation tank is uniform, which significantly improves the sedimentation conditions compared to inclined pipes;

3. The sludge discharge performance is much better than other forms of shallow sedimentation tanks, because this type of equipment has basically no lateral constraints, and the sedimentation area of the equipment is equal to the sludge discharge area.

3. High density sedimentation tank

The high-density sedimentation process is based on the traditional horizontal sedimentation tank, fully utilizing the principles of dynamic coagulation, accelerated flocculation, and shallow tank theory, optimizing the three processes of coagulation, enhanced flocculation, and inclined tube sedimentation. Mainly based on four mechanisms: unique integrated reaction zone design, lower flow rate variation from reaction zone to sedimentation zone, sludge circulation from sedimentation zone to reaction zone, and adoption of inclined tube sedimentation arrangement. The reaction tank is divided into two parts: a fast coagulation stirring reaction tank and a slow coagulation push flow reaction tank. The rapid coagulation stirring reaction tank introduces raw water into the center of the bottom plate of the reaction tank, and an impeller is installed in the middle of the cylinder. The function of the impeller is to evenly mix the water flow in the reaction tank and provide the necessary kinetic energy for flocculation and the distribution of polymeric electrolytes. The alum flower slowly enters the clarification tank from the pre settling tank, which can avoid alum flower breakage and generate vortices, allowing a large number of suspended solid particles to uniformly deposit in the area.

Alum flowers gather and concentrate sludge in the lower part of the clarification tank. Concentration is divided into two layers: the upper layer is the concentration of recycled sludge, and the lower layer is the place where a large amount of concentrated sludge is produced. The countercurrent inclined tube sedimentation zone will precipitate the remaining alum flowers. By fixing it in the clear water collection tank for hydraulic distribution, the inclined pipe will improve the uniform distribution of water flow. Clear water is collected by a collection tank system. Flocculants accumulate in the lower part of the clarification tank, and the formed sludge is also concentrated in this area.

This sedimentation tank has the following advantages:

1. Separate the mixing zone, flocculation zone and sedimentation tank, adopt a rectangular structure, and simplify the tank type;

2. The lower part of the sedimentation and separation area is equipped with a sludge concentration area, which occupies less land;

3. An external circulation of sludge is set up between the concentration zone and the mixing section. Some of the concentrated sludge is pumped back to the mechanical mixing tank and fully mixed with the raw water and coagulant. Through mechanical flocculation, a high concentration mixed flocculant is formed, which then enters the sedimentation zone for separation.

The new mid mounted high-density sedimentation tank is a new type of tank designed by Shanghai Municipal Engineering Research Institute. This process combines the advantages of inclined tube sedimentation tank, mechanical stirring clarification tank, and high-density sedimentation tank, integrating mixing, flocculation, sedimentation, and sludge concentration. The central high-density sedimentation tank has 5 process zones: mixing zone, flocculation reaction zone, separation sedimentation zone, concentrated sludge discharge zone, and separated effluent zone.

1. Small footprint;

2. The flocculation time is relatively short, and due to sludge reflux, a high concentration mixed liquid can be formed, greatly improving the flocculation effect and shortening the flocculation time in the mechanical stirring stage;

3. Uniform water distribution, due to the adoption of a uniform water distribution form from the pool to both sides, greatly shortens the water distribution path, effectively avoiding the problem of uneven water distribution affecting the effluent quality;

4. Reduced dosage of medication;

5. The water flow in the sedimentation tank is reasonable. As the water flow in and out of the sedimentation tank moves vertically from bottom to top and then from bottom to top, the separation effect of mud and water is more thorough, and it is not suitable to run alum flowers;

6. The water plant does not need to install a concentration tank. Due to the use of concentrated sludge scraping at the bottom of the sedimentation tank, the sludge has a high solid content and can be directly dehydrated;

7) The structural design is simple and the layout is simple and reasonable.

Interceptor sedimentation tank is a sedimentation tank that integrates various sedimentation effects such as gravity, collision adsorption force, contact adsorption force, etc., improving the efficiency of particle sedimentation. Intercepting sedimentation tank is equipped with an interceptor inside the tank, which sets obstacles for freely moving particles in the water. When particles move, they collide with the interceptor in three-dimensional space, so that the moving particles collide with the fixed interceptor in three-dimensional space and remain stationary, that is, the particle motion speed is zero.

This is because the particles are constrained by the frictional force of the interceptor, making it easy for them to attach and adsorb onto the interceptor. The interceptor adsorbs countless small particles that are still waiting for continuous motion to collide, forming a large mud mass. When the mud mass reaches sufficient mass, it overcomes the frictional force of the interceptor and precipitates. Due to the fact that the movement of particles in water collides and precipitates with a fixed interceptor in three-dimensional space, it exhibits multidirectionality and short distance. Regardless of the differences in particle size, mass, and shape, as long as it collides with the interceptor, it can adhere to the interceptor to form large mud masses and precipitates. Interception sedimentation has an ideal effect on treating low turbidity water. Without the use of coagulants, treating the same amount of water can reduce the dosage of coagulants in the interception sedimentation tank by about 20% compared to other sedimentation tanks.