Integrated efficient sedimentation tank

Abstract

The utility model discloses an integrated high-efficiency sedimentation tank which comprises a coagulation tank, a flocculation tank, a plug flow area and a sedimentation tank which are communicated in sequence, a first stirrer is arranged in the coagulating basin, and is provided with a first dosing assembly; a second stirrer and a guide cylinder are arranged in the flocculation tank, the guide cylinder is vertically arranged, the second stirrer is arranged in the guide cylinder, and the second stirrer is provided with a second dosing assembly; a communicating pipe is arranged in the flocculation basin; one end of the communicating pipe is connected with the lower part of the side wall of the coagulating basin, and the other end of the communicating pipe extends into the guide cylinder and is arranged below the second stirrer; and the coagulating basin is communicated with the flocculating basin through a communicating pipe. According to the technical scheme, a medicament and sewage are fully mixed, the flocculation effect is good, the sludge concentration is high, the precipitation effect is improved, the precipitation time is shortened, and the effluent quality is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of environmental protection, in particular to an integrated high-efficiency sedimentation tank. Background Art

[0002] The integrated high-efficiency sedimentation tank is a sewage treatment process that integrates the coagulation system, flocculation system, sedimentation system, sludge return system, dosing system and automatic control system to achieve rapid sedimentation. However, the following conditions will affect the efficient operation of the process: coagulants and coagulants are added at a single point, and the agents often flow into the next process before they are diluted, causing uneven mixing of the coagulation and flocculation processes, resulting in uneven size and distribution of alum flowers in the mixed liquid, which affects the subsequent sedimentation process and prevents the process from running efficiently. Summary of the invention

[0003] Technical problem: The technical problem to be solved by the utility model is to provide an integrated high-efficiency sedimentation tank to achieve full mixing of the reagent and sewage, good flocculation effect, high sludge concentration, improved sedimentation effect, shortened sedimentation time, and improved effluent quality.

[0004] Technical solution: To solve the above technical problems, the technical solution adopted by the embodiment of the utility model is:

[0005] An integrated high-efficiency sedimentation tank comprises a coagulation tank, a flocculation tank, a plug flow zone and a sedimentation tank which are connected in sequence; a first mixer is provided in the coagulation tank, and the first mixer is provided with a first dosing assembly; a water inlet is provided at the upper part of the side wall of the coagulation tank; a second mixer and a guide tube are provided in the flocculation tank, the guide tube is vertically arranged, the second mixer is arranged inside the guide tube, and the second mixer is provided with a second dosing assembly; a connecting pipe is provided in the flocculation tank; one end of the connecting pipe is connected to the lower part of the side wall of the coagulation tank, and the other end extends into the interior of the guide tube and is arranged below the second mixer; the coagulation tank and the flocculation tank are connected through a connecting pipe; the flocculation tank is provided with a water outlet; the water outlet of the flocculation tank is located at the lower part of the side wall close to the plug flow zone; the plug flow zone is provided with a water outlet; the water outlet of the plug flow zone is located at the upper part of the side wall close to the sedimentation tank.

[0006] As a preferred example, the first mixer includes a first impeller, a first driving member, a first dosing component and a first transmission shaft; the first dosing component includes a first distributor, a second distributor, a first dosing tube and a first doser; the first driving member is arranged above the coagulation tank, the upper end of the first transmission shaft is connected to the lower end of the first driving member, the lower end of the first transmission shaft is connected to the first impeller, the first distributor is arranged above the first impeller, the second distributor is arranged above the first distributor, the diameter of the second distributor is 0.5 to 0.8 times the diameter of the first distributor, the doser is arranged above the second distributor and is located on the upper part of the first transmission shaft; the first distributor, the second distributor and the first doser are all mounted on the first transmission shaft; one end of the first dosing tube is located above the coagulation tank, and the other end of the first doser passes through the upper surface of the coagulation tank and is connected to the first doser.

[0007] As a preferred example, the first transmission shaft is a structure with a hollow interior and a closed bottom, and the first distributor, the second distributor and the first dosing device are all provided with cavities therein, and the cavities are communicated with the first transmission shaft.

[0008] As a preferred example, the first distributor includes a main body and a connector; the connector is arranged at the upper end of the main body and connected to the main body; the connector is adapted to the first transmission shaft; a through hole is provided at the center of the main body, the through hole is adapted to the first transmission shaft, and the main body is provided with evenly distributed medicine outlets.

[0009] As a preferred example, the second mixer includes a second impeller, a second driving member, a second dosing assembly and a second transmission shaft; the second dosing assembly includes a third distributor, a fourth distributor, a second dosing pipe and a second doser; the second driving member is arranged above the flocculation tank, the upper end of the second transmission shaft is connected to the lower end of the second driving member, and the second impeller is connected to the lower end of the second transmission shaft; the third distributor is arranged above the second impeller, the fourth distributor is arranged above the third distributor, and the diameter of the third distributor is 0.5 to 0.8 times the diameter of the fourth distributor; the second doser is arranged above the fourth distributor and located at the upper part of the second transmission shaft; the third distributor, the fourth distributor and the second doser are all mounted on the second transmission shaft, one end of the second dosing pipe is located above the flocculation tank, and the other end of the second doser passes through the upper surface of the flocculation tank and is connected to the second doser.

[0010] As a preferred example, the second transmission shaft is a structure with a hollow interior and a closed bottom, and the third distributor, the fourth distributor and the second dosing device are all provided with cavities therein, and the cavities are all communicated with the second transmission shaft.

[0011] As a preferred example, during operation, the upper end surfaces of the first doser and the second doser are both located above the liquid surface.

[0012] As a preferred example, the first distributor, the second distributor, the third distributor and the fourth distributor have the same structure.

[0013] As a preferred example, the guide tube includes an upper tube and a lower tube; the upper tube is a hollow cylindrical structure with an open top; the lower tube is a hollow truncated cone structure, and the bottom end of the upper tube is connected to the top end of the lower tube.

[0014] As a preferred example, the sedimentation tank includes a pre-sedimentation zone and a sedimentation zone; the pre-sedimentation zone is arranged on the side close to the plug flow zone; the sedimentation zone is arranged on the side away from the plug flow zone; the sedimentation zone includes a scraper, an inclined pipe and a sump from bottom to top; a supernatant outlet is provided on the side of the sedimentation zone; a sludge outlet is provided at the bottom of the sedimentation tank, and a sludge discharge pipe and a sludge return pipe are provided at the lower part of the sludge outlet; the sludge return pipe is connected to the bottom of the coagulation tank.

[0015] Beneficial effects: Compared with the prior art, the technical solution of the utility model has the following beneficial effects: the technical solution of the utility model, by setting the dosing component, allows the agent and sewage to be mixed more fully, with good flocculation effect, high sludge concentration, and improved sedimentation effect. At the same time, it shortens the sludge sedimentation time and improves the water quality of the effluent. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural diagram of an embodiment of the utility model;

[0017] Figure 2 It is a structural diagram of a coagulation tank in an embodiment of the utility model;

[0018] Figure 3 This is a structural diagram of a flocculation tank according to an embodiment of the utility model;

[0019] Figure 4 It is a structural diagram of the first distributor of an embodiment of the utility model.

[0020] The figure includes: coagulation tank 1, first mixer 2, flocculation tank 3, second mixer 4, guide tube 5, plug flow area 6, sedimentation tank 7, supernatant outlet 8, sludge discharge pipe 9, sludge return pipe 10, connecting pipe 11, water inlet 12, first impeller 21, first distributor 221, second distributor 222, main body 223, connector 224, drug outlet 225, first driving member 23, first dosing pipe 24, first doser 25, first transmission shaft 26, second impeller 41, third distributor 421, fourth distributor 422, second driving member 43, second doser pipe 44, second doser 45, second transmission shaft 46, upper cylinder 51, lower cylinder 52, pre-sedimentation area 71, scraper 72, sedimentation area 73, sump 74, inclined pipe 75, sludge outlet 76. DETAILED DESCRIPTION

[0021] The technical solution of the utility model is described in detail below in conjunction with the accompanying drawings.

[0022] like Figure 1 As shown, an integrated high-efficiency sedimentation tank of the embodiment of the utility model comprises a coagulation tank 1, a flocculation tank 3, a flow-pushing area 6 and a sedimentation tank 7 which are connected in sequence; a first mixer 2 is arranged in the coagulation tank 1, and the first mixer 2 is provided with a first dosing assembly; a water inlet 12 is arranged on the upper part of the side wall of the coagulation tank 1; a second mixer 4 and a guide tube 5 are arranged in the flocculation tank 3, and the guide tube 5 is arranged vertically, and the second mixer 4 is arranged inside the guide tube 5, and the second mixer 4 is provided with A second dosing component; a connecting pipe 11 is provided in the flocculation tank 3; one end of the connecting pipe 11 is connected to the lower part of the side wall of the coagulation tank 1, and the other end extends into the interior of the guide tube 5 and is arranged below the second mixer 4; the coagulation tank 1 and the flocculation tank 3 are connected through the connecting pipe 11; the flocculation tank 3 is provided with a water outlet; the water outlet of the flocculation tank 3 is located at the lower part of the side wall near the plug flow area 6; the plug flow area 6 is provided with a water outlet; the water outlet of the plug flow area 6 is located at the upper part of the side wall near the sedimentation tank 7.

[0023] In an integrated high-efficiency sedimentation tank of the above structure, by setting the first dosing component in the coagulation tank, the dilution mode is changed from single-point dilution to circumferential multi-point dilution, thereby improving the mixing effect. By setting the second dosing component in the flocculation tank, the flocculation effect is improved. Through the cooperation of the first dosing component and the second dosing component, the reagent and sewage are fully mixed, the mixing effect and the flocculation effect are improved, and then the sludge density is higher, and the sedimentation effect is improved. At the same time, through the action of the two dosing components, the sludge sedimentation time is reduced and the effluent water quality is improved.

[0024] The working process of the sedimentation tank of the above embodiment is as follows: sewage enters the coagulation tank 1 through the water inlet pipe 12, and at the same time, the coagulant is added to the first doser 25 through the first doser pipe 24, and then the coagulant enters the first transmission shaft 26 through the cavity of the first doser 25, and then flows into the second distributor 222 and the first distributor 221 through the first transmission shaft 26. The second distributor 222 and the first distributor 221 rotate synchronously with the mixer, and at this time, the coagulant flies out of the drug outlet and mixes with the sewage. The single-point dilution is changed to circumferential multi-point dilution, which greatly improves the mixing effect. Two distributors are set up to perform a second dilution and mixing. The dilution and mixing effects are gradually improved, and while improving the mixing effect, the mixed liquid is also made more uniform. At this time, the first impeller rotating at high speed mixes the mixed liquid again after two dilutions and mixing, so that the agent is fully diluted to form small flocs.

[0025] A coagulant is added to the second dosing tube 44, and the coagulant enters the second dosing device 45 through the second dosing tube 44, and then enters the second transmission shaft 46 through the cavity of the second dosing tube 45, and then flows into the fourth distributor 422 and the third distributor 421 from the second transmission shaft 46. The fourth distributor 422 and the third distributor 421 rotate synchronously with the mixer. At this time, the coagulant flies out through the outlet and mixes with the external liquid, thereby improving the mixing effect. When the mixed liquid with fine flocs in the coagulation tank 1 enters the flocculation tank 3, the mixed liquid enters the guide tube 5 through the connecting tube 11, and the rotating second impeller 41 lifts the mixed liquid in the guide tube upward.

[0026] When the mixed liquid in the guide tube 5 moves upward, it is continuously mixed again with the mixed liquid that has been initially diluted and mixed with the flocculant in the middle and upper part of the guide tube. After flowing out from the upper part of the guide tube, it moves from top to bottom outside the guide tube. The mixed liquid enters the guide tube again under the lifting of the second mixer 4 for circulation, so that the alum flowers continue to grow. The mixed liquid flows into the plug flow area 6 and the pre-precipitation area 71 in turn, and the size of the alum flowers increases here, the sedimentation rate is relatively high, and most of the coagulation flocs with relatively high density settle in the pre-precipitation area 71. The unsettled liquid with sludge enters the sedimentation area 73, and the sludge is precipitated by the combined action of the scraper 72, the inclined pipe 75, and the water collection tank 74 in the sedimentation area 73. A part of it enters the coagulation tank 1 through the sludge return pipe 10, so that the coagulant in the sludge is recycled. The other part of the sludge is discharged from the system through the residual sludge pipe 9. The clear water after precipitation is collected by the water collection tank 74 and flows out through the supernatant outlet 8.

[0027] like Figure 2As shown, as a preferred example, the first mixer 2 includes a first impeller 21, a first driving member 23, a first dosing assembly and a first transmission shaft 26; the first dosing assembly includes a first distributor 221, a second distributor 222, a first dosing pipe 24 and a first dosing device 25; the first driving member 23 is arranged above the coagulation tank 1, the upper end of the first transmission shaft 26 is connected to the lower end of the first driving member 23, the lower end of the first transmission shaft 26 is connected to the first impeller 21, the first distributor 221 is arranged above the first impeller 21, and the The second distributor 222 is arranged above the first distributor 221, and the diameter of the second distributor 222 is 0.5 to 0.8 times the diameter of the first distributor 221. The doser 25 is arranged above the second distributor 222 and located at the upper part of the first transmission shaft 26; the first distributor 221, the second distributor 222 and the first doser 25 are all mounted on the first transmission shaft 26; one end of the first doser pipe 24 is located above the coagulation tank 1, and the other end of the first doser pipe 24 passes through the upper surface of the coagulation tank 1 and is connected to the first doser 25. A first agitator 2 is arranged in the coagulation tank 1. The first agitator 2 adopts a paddle-type agitator with a high impeller speed, and quickly stirs the sewage and coagulant entering the tank. After the sewage enters the coagulation tank 1, the coagulant is added to the first doser pipe 24, and the coagulant flows through the first doser 25 and the first transmission shaft 26 to reach the second distributor 222 and the first distributor 221. Since the second distributor 222 and the first distributor 221 are both provided with drug outlets and rotate synchronously with the first mixer 2, they are integrated into the liquid in multiple directions, thereby improving the mixing effect. By setting up two distributors, the coagulant can enter the liquid step by step, making the coagulant and liquid mixed more evenly.

[0028] As a preferred example, the first transmission shaft 26 is a structure with a hollow interior and a closed bottom. The first distributor 221, the second distributor 222 and the first doser 25 are all provided with cavities, and the cavities are connected to the first transmission shaft 26. When the coagulant enters the first doser 25 from the first dosing tube 24, since the doser 25 is provided with cavities and is connected to the first transmission shaft 26, the coagulant can smoothly enter the first transmission shaft 26. As the coagulant slowly falls and fills a certain height, the coagulant in the first transmission shaft 26 will enter the first distributor 221 and the second distributor 222. When the first mixer 2 rotates, the coagulant in the first distributor 221 and the second distributor 222 flies out from the drug outlet. The mixing is completed more smoothly and efficiently.

[0029] like Figure 4As shown, as a preferred example, the first distributor 221 includes a body 223 and a connector 224; the connector 224 is arranged at the upper end of the body 223 and connected to the body 223; the connector 224 is adapted to the first transmission shaft 26; a through hole is arranged at the center of the body 223, the through hole is adapted to the first transmission shaft 26, and the body 223 is provided with evenly distributed drug outlets 225. The first distributor 221 is fixed to the first transmission shaft 26 through the connector 224 and the through hole in the center of the body 223, which can be fixed more firmly and will not cause the first distributor 221 to be separated during rotation. The through hole is adapted to the first transmission shaft 26 to ensure that the medicine of the first transmission shaft 26 flows into the distributor, and the multiple evenly distributed drug outlets 225 are arranged to ensure that the coagulant flies into the liquid smoothly in multiple directions, improve the mixing effect, and make the mixed liquid more uniform.

[0030] like Figure 3 As shown, as a preferred example, the second mixer 4 includes a second impeller 41, a second driving member 43, a second dosing assembly and a second transmission shaft 46; the second dosing assembly includes a third distributor 421, a fourth distributor 422, a second dosing pipe 44 and a second dosing device 45; the second driving member 43 is arranged above the flocculation tank 3, the upper end of the second transmission shaft 46 is connected to the lower end of the second driving member 43, and the second impeller 41 is connected to the lower end of the second transmission shaft 46; the third distributor 421 is arranged above the second impeller 41, the The fourth distributor 422 is arranged above the third distributor 421, and the diameter of the third distributor 421 is 0.5 to 0.8 times the diameter of the fourth distributor 422; the second doser 45 is arranged above the fourth distributor 422 and located at the upper part of the second transmission shaft 46; the third distributor 421, the fourth distributor 422 and the second doser 45 are all mounted on the second transmission shaft 46, one end of the second doser pipe 44 is located above the flocculation tank 3, and the other end of the second doser pipe 44 passes through the upper surface of the flocculation tank 3 and is connected to the second doser 45. A second mixer 4 is arranged in the flocculation tank 3, and the second mixer 4 is a frame mixer with a low impeller speed, which is slowly mixed with the mixed liquid entering the tank to form larger alum flowers, creating conditions for subsequent efficient precipitation. Flocculant is added to the second doser pipe 44, and the flocculant flows through the second doser 45 and the second transmission shaft 46, and reaches the fourth distributor 422 and the third distributor 422. Finally, when the third distributor 421 and the fourth distributor 422 rotate, the flocculant flies into the liquid. The two distributors are provided to make the flocculation effect better and more uniform.

[0031] As a preferred example, the second transmission shaft 46 is a structure with a hollow interior and a closed bottom, and the third distributor 421, the fourth distributor 422 and the second doser 45 are all provided with cavities inside, and the cavities are all connected to the second transmission shaft 46. After the flocculant is added through the second doser pipe 44, the flocculant reaches the fourth distributor 422 and the third distributor 421 after passing through the second doser 45 and the second transmission shaft 46, and finally flies smoothly to the outside and mixes with the external mixed liquid under the driving of the rotation of the second mixer 4, thereby improving the mixing effect and the flocculation effect.

[0032] As a preferred example, when working, the upper end surfaces of the first doser 25 and the second doser 45 are both located above the liquid surface. The first doser 25 is arranged above the liquid surface to ensure that all the coagulants enter the first distributor 221 and the second distributor 222 through the first transmission shaft 26, and then fly uniformly into the water body of the coagulation tank 1 through the first distributor 221 and the second distributor 222 for uniform mixing and dilution.

[0033] The second doser 45 is arranged above the liquid surface to ensure that all the coagulant enters the third distributor 421 and the fourth distributor 422 through the second transmission shaft 46, and then flies evenly into the water body in the guide tube 5 of the flocculation tank 3 from the third distributor 421 and the fourth distributor 422 for uniform mixing and dilution to obtain a large amount of high-density homogeneous alum flowers.

[0034] As a preferred example, the first distributor 221, the second distributor 222, the third distributor 421 and the fourth distributor 422 have the same structure. The four distributors have the same structure, are all flat drum-shaped, and are all distributed with drug outlets on the side. It can ensure that both the coagulant and the flocculant can smoothly enter the water body for mixing, thereby improving the mixing effect. At the same time, the diameter of the first distributor 221 is larger than the diameter of the second distributor 222, and the second distributor 222 is located above the first distributor 221. Since the sewage moves from top to bottom in the coagulation tank 1, when the coagulant and the sewage are mixed, they can be mixed step by step, thereby improving the mixing effect and making the mixed liquid more uniform; the diameter of the third distributor 421 is smaller than the diameter of the fourth distributor 422, and the third distributor 421 is located below the fourth distributor 422; since the liquid moves from bottom to top in the guide tube 5 of the flocculation tank 3, when the flocculant and the sewage are mixed, they can be mixed step by step, thereby improving the mixing effect and making the mixed liquid more uniform.

[0035] As a preferred example, the guide tube 5 includes an upper cylinder 51 and a lower cylinder 52; the upper cylinder 51 is a hollow cylindrical structure with an open top; the lower cylinder is a hollow truncated cone structure, and the bottom end of the upper cylinder 51 is connected to the top end of the lower cylinder 52. By setting the guide tube 5, after entering the flocculation tank 3, the coagulant mixed liquid moves upward inside the guide tube 5 under the action of the guide tube 5, and is secondary mixed with the flocculant mixed liquid, and then overflows from the upper end of the guide tube 5 under the action of the second mixer 4, and moves from top to bottom outside the guide tube, and then the mixed liquid enters the guide tube again under the lifting of the second mixer 4 to circulate, so that the alum flocs continue to grow.

[0036] As a preferred example, the sedimentation tank 7 includes a pre-sedimentation area 71 and a sedimentation area 73; the pre-sedimentation area 71 is arranged on a side close to the plug flow area 6; the sedimentation area 73 is arranged on a side away from the plug flow area 6; the sedimentation area 73 includes a scraper 72, an inclined pipe 75 and a water collection tank 74 from bottom to top; a supernatant outlet 8 is arranged on the side of the sedimentation area 73; a sludge outlet 76 is arranged at the bottom of the sedimentation tank 7, and a sludge discharge pipe 9 and a sludge return pipe 10 are arranged at the lower part of the sludge outlet 76; the sludge return pipe 10 is connected to the bottom of the coagulation tank 1. After the sewage realizes the crowded sedimentation, sludge filtration and sedimentation process in the sedimentation area 73, it rises to the inclined pipe 75. The inclined pipe 75 uses the shallow pool principle to reduce the path of the suspended particles in the water to settle, shorten the sedimentation time, and the clear water after sedimentation is discharged from the supernatant outlet 8 through the water collection tank 74.

[0037] A part of the sludge in the bottom pit of the sedimentation tank 7 enters the coagulation tank 1 through the sludge return pipe 10, so that the coagulant in the sludge is recycled and the operating cost is reduced. The other part of the sludge is discharged out of the system through the residual sludge pipe.

[0038] The above shows and describes the basic principles, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above specific embodiments. The above specific embodiments and the description in the specification are only for further illustrating the principles of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection claimed by the utility model is defined by the claims and their equivalents.

Claims

1. An integrated high-efficiency sedimentation tank, characterized in that: The invention comprises a coagulation tank (1), a flocculation tank (3), a flow-pushing area (6) and a sedimentation tank (7) which are connected in sequence; a first mixer (2) is arranged in the coagulation tank (1), and the first mixer (2) is provided with a first dosing component; a water inlet (12) is arranged on the upper part of the side wall of the coagulation tank (1); a second mixer (4) and a guide tube (5) are arranged in the flocculation tank (3), and the guide tube (5) is arranged vertically, and the second mixer (4) is arranged inside the guide tube (5), and the second mixer (4) is provided with a second dosing component; the flocculation tank (3) is provided with a first mixer (2), and the first mixer (2) is provided with a first dosing component; the flocculation tank (3) is provided with a second mixer (4) and a guide tube (5), and the guide tube (5) is arranged vertically, and the second mixer (4) is arranged inside the guide tube (5), and the second mixer (4) is provided with a second dosing component; the flocculation tank (3) is provided with a first mixer (2), and the first mixer (2) is provided with a first ...1) is provided with a first mixer (2), and the first mixer A connecting pipe (11) is provided in the pool (3); one end of the connecting pipe (11) is connected to the lower part of the side wall of the coagulation pool (1), and the other end extends into the interior of the guide tube (5) and is arranged below the second mixer (4); the coagulation pool (1) and the flocculation pool (3) are connected through the connecting pipe (11); the flocculation pool (3) is provided with a water outlet; the water outlet of the flocculation pool (3) is located at the lower part of the side wall close to the plug flow area (6); the plug flow area (6) is provided with a water outlet; the water outlet of the plug flow area (6) is located at the upper part of the side wall close to the sedimentation pool (7).

2. The sedimentation tank according to claim 1, characterized in that: The first mixer (2) comprises a first impeller (21), a first driving member (23), a first dosing assembly and a first transmission shaft (26); the first dosing assembly comprises a first distributor (221), a second distributor (222), a first dosing pipe (24) and a first dosing device (25); the first driving member (23) is arranged above the coagulation tank (1), the upper end of the first transmission shaft (26) is connected to the lower end of the first driving member (23), the lower end of the first transmission shaft (26) is connected to the first impeller (21), the first distributor (221) is arranged above the first impeller (21), and the second distributor (222) is arranged above the first impeller (21). The distributor (222) is arranged above the first distributor (221), the diameter of the second distributor (222) is 0.5 to 0.8 times the diameter of the first distributor (221), the doser (25) is arranged above the second distributor (222) and is located on the upper part of the first transmission shaft (26); the first distributor (221), the second distributor (222) and the first doser (25) are all mounted on the first transmission shaft (26); one end of the first dosing pipe (24) is located above the coagulation tank (1), and the other end of the first dosing pipe (24) passes through the upper surface of the coagulation tank (1) and is connected to the first doser (25).

3. The sedimentation tank according to claim 2, characterized in that: The first transmission shaft (26) is a structure with a hollow interior and a closed bottom. The first distributor (221), the second distributor (222) and the first dosing device (25) are all provided with cavities therein, and the cavities are communicated with the first transmission shaft (26).

4. The sedimentation tank according to claim 2, characterized in that: The first distributor (221) comprises a main body (223) and a connector (224); the connector (224) is arranged at the upper end of the main body (223) and connected to the main body (223); the connector (224) is adapted to the first transmission shaft (26); a through hole is provided at the center of the main body (223), the through hole is adapted to the first transmission shaft (26), and the main body (223) is provided with evenly distributed medicine outlets (225).

5. The sedimentation tank according to claim 4, characterized in that: The second mixer (4) comprises a second impeller (41), a second driving member (43), a second dosing assembly and a second transmission shaft (46); the second dosing assembly comprises a third distributor (421), a fourth distributor (422), a second dosing pipe (44) and a second dosing device (45); the second driving member (43) is arranged above the flocculation tank (3), the upper end of the second transmission shaft (46) is connected to the lower end of the second driving member (43), and the second impeller (41) is connected to the lower end of the second transmission shaft (46); the third distributor (421) is arranged above the second impeller (41), the fourth distributor (422) is arranged above the second impeller (41), and the The doser (422) is arranged above the third distributor (421), and the diameter of the third distributor (421) is 0.5 to 0.8 times the diameter of the fourth distributor (422); the second doser (45) is arranged above the fourth distributor (422) and is located on the upper part of the second transmission shaft (46); the third distributor (421), the fourth distributor (422) and the second doser (45) are all mounted on the second transmission shaft (46), one end of the second dosing pipe (44) is located above the flocculation tank (3), and the other end of the second dosing pipe (44) passes through the upper surface of the flocculation tank (3) and is connected to the second doser (45).

6. The sedimentation tank according to claim 5, characterized in that: The second transmission shaft (46) is a structure with a hollow interior and a closed bottom. The third distributor (421), the fourth distributor (422) and the second dosing device (45) are all provided with cavities therein, and the cavities are all communicated with the second transmission shaft (46).

7. The sedimentation tank according to claim 5, characterized in that: When in operation, the upper end surfaces of the first doser (25) and the second doser (45) are both located above the liquid surface.

8. The sedimentation tank according to claim 5, characterized in that: The first distributor (221), the second distributor (222), the third distributor (421) and the fourth distributor (422) have the same structure.

9. The sedimentation tank according to claim 1, characterized in that: The guide cylinder (5) comprises an upper cylinder (51) and a lower cylinder (52); the upper cylinder (51) is a hollow cylindrical structure with an open top; the lower cylinder is a hollow truncated cone structure, and the bottom end of the upper cylinder (51) is connected to the top end of the lower cylinder (52).

10. The sedimentation tank according to claim 1, characterized in that: The sedimentation tank (7) comprises a pre-sedimentation zone (71) and a sedimentation zone (73); the pre-sedimentation zone (71) is arranged on a side close to the plug flow zone (6); the sedimentation zone (73) is arranged on a side away from the plug flow zone (6); the sedimentation zone (73) comprises a scraper (72), an inclined pipe (75) and a water collecting tank (74) in order from bottom to top; a supernatant outlet (8) is arranged on the side of the sedimentation zone (73); a sludge outlet (76) is arranged at the bottom of the sedimentation tank (7), and a sludge discharge pipe (9) and a sludge return pipe (10) are arranged at the lower part of the sludge outlet (76); the sludge return pipe (10) is connected to the bottom of the coagulation tank (1).

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