Tail water treatment system and method for eel culture

Abstract

The invention relates to a tail water treatment system and method for eel culture. A tail water treatment system for eel culture comprises a rotational flow sedimentation tank, a water inlet of the rotational flow sedimentation tank is connected with a tail water outlet of a culture pond, a water outlet of the rotational flow sedimentation tank is connected with a water inlet of a fiber filter, and a water outlet of the fiber filter is connected with a water inlet of a clean water tank through a third pipe set. A water outlet of the clean water tank is connected with a water inlet of the buffer tank; a water outlet of the buffer tank is connected with a culture water inlet of the culture tank. By arranging the rotational flow sedimentation tank and the fiber filter and based on a water circulation mode, the eel breeding tail water can be treated to obtain clear water meeting the eel breeding requirement, the clear water flows back to the breeding pond to be supplemented with breeding water, and therefore cyclic utilization of the breeding water is achieved, growth of eels is facilitated, and water resources are effectively saved.

Description

Technical Field

[0001] The invention relates to the technical field of eel breeding, in particular to a tail water treatment system and method for eel breeding. Background Art

[0002] Eel has always been popular in the market for its unique taste, rich nutritional value and medicinal value. With the improvement of people's living standards and the change of consumption concepts, the demand for eels is also increasing.

[0003] In the prior art, eel farms usually use closed breeding ponds for eel breeding, and regularly replace the pond water to maintain water quality. The water in the breeding pond cannot be effectively circulated, and often requires a large amount of new water to be replenished to maintain a good breeding environment and ensure the normal growth of eels and other breeding organisms. This method has the following problems:

[0004] (1) Eel tail water contains a large amount of particulate matter. If it is discharged directly without being collected and treated, it will aggravate the eutrophication of the water body and water pollution, causing damage to the surrounding ecological environment;

[0005] (2) Due to the high viscosity of aquaculture water, extremely high requirements are placed on the capacity of tailwater treatment equipment;

[0006] (3) Centralized water exchange results in large single-time drainage volume and short time. Based on 10,000 cubic meters of aquaculture water, the single-time drainage volume is 2000m 3 , with a displacement of about 1000m per hour 3 Not only does it waste precious water resources, but it may also cause stress to the eels due to improper operation during the water change process, which is not conducive to the growth of eels. Summary of the invention

[0007] Based on this, it is necessary to provide a tailwater treatment system and method for eel farming to address the problems in the prior art that the pond water needs to be replaced regularly to maintain the water quality in the eel farming pond, resulting in difficulties in subsequent treatment of the eel farming tailwater, high performance requirements for the treatment equipment, waste of water resources, and being unfavorable to the growth of eels.

[0008] The technical solution adopted by the present invention is as follows:

[0009] A tailwater treatment system for eel farming, comprising a cyclone sedimentation tank, wherein the water inlet of the cyclone sedimentation tank is connected to the tailwater outlet of a farming pond, the water outlet of the cyclone sedimentation tank is connected to the water inlet of a fiber filter, the water outlet of the fiber filter is connected to the water inlet of a clear water tank through a third pipe group, the water outlet of the clear water tank is connected to the water inlet of a buffer tank, and the water outlet of the buffer tank is connected to the farming water inlet of the farming pond;

[0010] The tail water in the breeding pond flows into the cyclone sedimentation tank, and drives the water in the cyclone sedimentation tank to rotate and rise, so that the upper water in the cyclone sedimentation tank flows into the interior of the fiber filter, and becomes clear water after being filtered by the fiber filter. The clear water flows into the clear water tank to supplement the breeding water in the breeding pond.

[0011] As a further improvement of the above technical solution:

[0012] The structure of the cyclone sedimentation tank is as follows: it includes a sedimentation tank body, a water turning weir is arranged on the inner wall surface of the sedimentation tank body along the circumferential direction, the water turning weir is arranged obliquely, so that a water collecting ditch with a decreasing width from top to bottom is formed between the wall surface of the water turning weir and the inner wall surface of the sedimentation tank body, an inlet pipe and an outlet pipe are respectively installed on the inner wall surface of the sedimentation tank body, the outlet of the outlet pipe leads to the water collecting ditch, the inlet pipe is arranged below the outlet pipe, and a slope is arranged on the inner wall surface of the sedimentation tank body below the inlet pipe;

[0013] The tail water in the breeding pond flows into the sedimentation tank body through the water inlet pipe. The tail water in the sedimentation tank body collides with the slope under the action of its own flow velocity, so that a rotating upward water flow is formed inside the sedimentation tank body, and then the upper water body inside the sedimentation tank body overflows the water weir into the water collecting ditch. The water in the water collecting ditch flows into the fiber filter through the water outlet pipe.

[0014] A sewage outlet is provided at the center of the bottom wall of the sedimentation tank body, the sewage outlet is connected to the sludge inlet of the sewage collecting tank through a sewage pipe, the sewage outlet of the sewage collecting tank is connected to the sewage inlet of the air flotation machine, the clean water outlet of the air flotation machine is connected to the water inlet of the biological digestion tank, the scum outlet of the air flotation machine is connected to the sludge inlet of the sludge tank, the sludge outlet of the sludge tank is connected to the sludge inlet of the plate and frame filter press, and the sewage outlet of the plate and frame filter press is connected to the sewage inlet of the sewage collecting tank.

[0015] The air flotation machine is equipped with a dosing device.

[0016] The backwash discharge port of the fiber filter is connected to the sludge inlet of the sludge collecting tank.

[0017] The water inlet of the biological digestion tank is also connected to the water outlet of the buffer tank.

[0018] The water inlet pipe enters the interior of the sedimentation tank body along a tangent line of the side wall surface of the sedimentation tank body.

[0019] The structure of the fiber filter is as follows: it comprises an outer shell, and a filtering device is installed inside the outer shell to filter the water in the outer shell.

[0020] The structure of the filtering device is as follows: it comprises at least one filter disc, and the outer surface of the single filter disc is wrapped with a fiber filter cloth;

[0021] It also includes at least one connecting rod, one end of the single connecting rod is hinged to the fixed cantilever, and at the same time, the other end of the single connecting rod is hinged to the mud suction box. The mud suction boxes are arranged in a one-to-one correspondence with the filter discs, and two adjacent mud suction boxes are connected by a spring. Under the action of the spring, the suction nozzle of a single mud suction box presses the fiber filter cloth on the corresponding filter disc.

[0022] A method for treating tailwater of eel farming based on the above system comprises the following steps:

[0023] Step 1: The tail water of the breeding pond enters the cyclone sedimentation tank through the first pipe group, and the cyclone sedimentation tank performs sedimentation treatment on the tail water based on centrifugal force and gravity;

[0024] Step 2: The supernatant in the cyclone sedimentation tank overflows into the second tube group, and is introduced into the fiber filter through the second tube group for filtration to become clear water;

[0025] Step 3: The clean water in the fiber filter flows into the clean water tank through the third pipe group for recycling or direct discharge after reaching the standard.

[0026] The beneficial effects of the present invention are as follows:

[0027] The invention has a compact and reasonable structure and is easy to operate. By arranging a cyclone sedimentation tank and a fiber filter, based on a water circulation mode, the tail water of eel farming can be treated to obtain clean water that meets the requirements of eel farming. The clean water flows back to the breeding pond for breeding water replenishment, thereby realizing the recycling of breeding water, being beneficial to the growth of eels, and effectively saving water resources.

[0028] The present invention also has the following advantages:

[0029] (1) The present invention only requires one water extraction process, and the tail water extracted from the aquaculture pond is completely used for the subsequent process by gravity, which effectively saves the cost of secondary water extraction and can minimize the disturbance of particulate matter in the water body inside the cyclone sedimentation tank, effectively reducing the difficulty and cost of subsequent treatment.

[0030] (2) The present invention provides a water inlet pipe and a slope that enter the interior of the sedimentation tank body along a tangent line of the side wall surface, so that the tail water entering the sedimentation tank body can push the water inside the sedimentation tank body to rotate and rise in a certain rotation direction.

[0031] (3) The present invention can prevent the particles inside the sedimentation tank from rising by setting a water-turning weir. The blocked particles will sink to the bottom of the tank under the action of the vortex flow of the water in the tank and be discharged from the sewage pipe.

[0032] (4) The present invention provides an air flotation sedimentation tank inside the air flotation machine and integrates it at the front end thereof. After the sewage enters the air flotation machine, it can first be separated into solid and liquid in the air flotation sedimentation tank, so that the heavier particles in the sewage can be deposited, thereby preventing such heavier particles from entering the rear section of the air flotation machine and increasing the workload of bottom sewage discharge, thereby effectively improving the operation effect and work efficiency of the air flotation machine.

[0033] (5) The present invention provides a spring, a connecting rod, and a fixed cantilever so that the suction box and the filter disc move together, thereby ensuring that the pressing force between the suction nozzle of the suction box and the fiber filter cloth is always balanced, ensuring the consistency of the backwash effect of the filter disc, and avoiding wear of the fiber filter cloth caused by excessive force on one side, thereby increasing the service life of the fiber filter cloth.

[0034] (6) The present invention adopts a three-layer structure of fiber filter cloth, wherein a three-dimensional space is arranged inside the fiber filter cloth, and a filter cloth medium with an effective filtration depth of 3mm-5mm can be formed on the surface of the fiber filter cloth, so that the fiber filter cloth can directly intercept and adsorb fine particles, has high filtration efficiency, low manufacturing cost, and large dirt holding capacity. It is suitable for efficient interception of high-viscosity liquids or small-diameter particles, and can be effectively used for filtering eel farming. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structure of the present invention.

[0036] Figure 2 It is a schematic diagram of the present invention in working state.

[0037] Figure 3 It is a schematic diagram of the structure of the cyclone sedimentation tank in the present invention.

[0038] Figure 4 for Figure 3 Top view of the .

[0039] Figure 5 It is a schematic diagram of the structure of the filtering device in the present invention.

[0040] Figure 6 for Figure 5 A partial enlarged view of point A in the middle.

[0041] Among them: 1. Breeding pond; 2. Cyclone sedimentation tank; 3. Fiber filter; 4. Clear water tank; 5. Buffer tank; 6. Filter device; 7. Ozone generator; 8. Sewage collection tank; 9. Air flotation machine; 10. Dosing device; 11. Sludge tank; 12. Plate and frame filter press; 13. Biological digestion tank;

[0042] 201, sedimentation tank body; 202, slope; 203, water inlet pipe; 204, sewage pipe; 205, water outlet pipe; 206, water weir; 207, water collection ditch;

[0043] 601, filter plate; 602, fixed cantilever; 603, mud suction box; 604, spring; 605, connecting rod. DETAILED DESCRIPTION

[0044] The specific implementation of the present invention will be described below in conjunction with the accompanying drawings.

[0045] Traditional eel farms usually adopt centralized water exchange to replace the aquaculture water in the aquaculture pond. The amount of water exchanged each time is large, and in order to avoid affecting the eels in the aquaculture pond, the water exchange is required to be completed in the shortest possible time. Based on 10,000 cubic meters of aquaculture water, a single water discharge of 2000m3 is required. 3 , hourly displacement of about 1000m 3 In addition, the water used for eel farming has high viscosity, which places extremely high performance requirements on water exchange equipment.

[0046] Based on this, Figure 1-Figure 6 As shown, this embodiment proposes a tailwater treatment system for eel farming, including a cyclone sedimentation tank 2, the water inlet of the cyclone sedimentation tank 2 is connected to the tailwater outlet of the farming pond 1, the water outlet of the cyclone sedimentation tank 2 is connected to the water inlet of the fiber filter 3, the water outlet of the fiber filter 3 is connected to the water inlet of the clean water tank 4 through the third pipe group, the water outlet of the clean water tank 4 is connected to the water inlet of the buffer tank 5, and the water outlet of the buffer tank 5 is connected to the farming water inlet of the farming pond 1; the tailwater in the farming pond 1 flows into the cyclone sedimentation tank 2, and drives the water in the cyclone sedimentation tank 2 to rotate and rise, so that the upper water in the cyclone sedimentation tank 2 flows into the interior of the fiber filter 3, and becomes clean water after being filtered by the fiber filter 3, and the clean water flows into the clean water tank 4 to supplement the farming water of the farming pond 1. By setting up the cyclone sedimentation tank 2 and the fiber filter 3, based on the water circulation mode, the eel tail water can be fully separated from the solid and liquid, so as to obtain clean water that meets the requirements of eel farming. The clean water flows back to the breeding pond 1 for breeding water replenishment, thereby realizing the recycling of breeding water, which is beneficial to the growth of eels and effectively saves water resources.

[0047] In addition, the tail water treatment system of this embodiment only pumps water once during the whole process, and the tail water pumped from the breeding pond 1 completes the subsequent process completely by gravity, effectively saving the cost of secondary water pumping, and can minimize the disturbance of particulate matter in the water body inside the cyclone sedimentation tank 2, effectively reducing the difficulty and cost of subsequent treatment.

[0048] The cyclone sedimentation tank 2 is used for preliminary solid-liquid separation of eel tail water. Figure 3-Figure 4As shown, the structure of the cyclone sedimentation tank 2 is as follows: it includes a sedimentation tank body 201, and a water turning weir 206 is arranged on the inner wall surface of the sedimentation tank body 201 along the circumferential direction. The water turning weir 206 is arranged obliquely, so that a water collecting ditch 207 with a decreasing width from top to bottom is formed between the wall surface of the water turning weir 206 and the inner wall surface of the sedimentation tank body 201, and an inlet pipe 203 and an outlet pipe 205 are respectively installed on the inner wall surface of the sedimentation tank body 201, and the outlet pipe 205 leads to the water collecting ditch 207, and the inlet pipe 203 is arranged on the outlet pipe 205. The inner wall surface of the sedimentation tank body 201 below the water inlet pipe 203 is provided with a slope 202; the tail water in the breeding pond 1 flows into the sedimentation tank body 201 through the water inlet pipe 203, and the tail water inside the sedimentation tank body 201 collides with the slope 202 under the action of its own flow rate, so that a rotating upward water flow is formed inside the sedimentation tank body 201, and then the upper water body inside the sedimentation tank body 201 overflows the water turning weir 206 into the water collecting ditch 207, and the water in the water collecting ditch 207 flows into the fiber filter 3 through the water outlet pipe 205. The water turning weir 206 adopts a 304 stainless steel plate with a thickness of 1.0 mm, and the connection with the side wall of the sedimentation tank body 201 is sealed with cement.

[0049] A sewage outlet is provided at the center of the bottom wall of the sedimentation tank body 201, and the sewage outlet is connected to the sludge inlet of the sewage collection tank 8 through a sewage pipe 204, the sewage outlet of the sewage collection tank 8 is connected to the sewage inlet of the air flotation machine 9, the clean water outlet of the air flotation machine 9 is connected to the water inlet of the biological digestion tank 13, the scum outlet of the air flotation machine 9 is connected to the inlet of the sludge tank 11, the outlet of the sludge tank 11 is connected to the sludge inlet of the plate-frame filter press 12, and the sewage outlet of the plate-frame filter press 12 is connected to the sewage inlet of the sewage collection tank 8. The sewage pipe 204 is a pre-buried pipeline, and the sludge in the sedimentation tank body 201 flows into the sewage collection tank 8 through the sewage pipe 204 for secondary solid-liquid separation treatment.

[0050] The water inlet pipe 203 enters the sedimentation tank body 201 along the tangent of the side wall of the sedimentation tank body 201. The cyclone sedimentation tank 2 adopts a tangential feeding method, and the tail water enters the sedimentation tank body 201 along the tangent of the side wall of the sedimentation tank body 201. Relying on its own flow velocity and under the action of the slope 202, the water inside the sedimentation tank body 201 rotates and rises along a certain rotation direction (counterclockwise in the northern hemisphere and clockwise in the southern hemisphere).

[0051] The water inlet pipe 203, the sewage pipe 204 and the water outlet pipe 205 are all made of UPVC hard polyvinyl chloride material, which is light and durable.

[0052] Since the water inlet pipe 203 enters along the tangent direction of the side wall of the sedimentation tank body 201, some lighter particles will rotate and rise along the tank wall with the water flow. By setting up a water-turning weir 206, the particles inside the sedimentation tank body 201 can be blocked from rising. The blocked particles will sink to the bottom of the tank under the action of the vortex of the water in the tank and be discharged from the sewage pipe 204.

[0053] When the weir 206 is designed, its angle and width will be adjusted according to the particle size and weight of the particles in the tail water and the unit processing capacity of the cyclone sedimentation tank 2.

[0054] The cyclone sedimentation tank 2 is constructed of a steel-concrete structure or a fiberglass assembled structure. The sedimentation tank body 201 is cylindrical in shape and has a conical bottom. The area and height of the sedimentation tank body 201 are calculated based on the amount of water treated per hour:

[0055] The area of ​​the sedimentation tank body 201 S (㎡) = the amount of water to be treated L (m 3 / h) / unit area loadθ(m 3 / ㎡·h)·Correction coefficient α;

[0056] The height h (m) of the sedimentation tank body 201 = unit area load θ (m 3 / ㎡·h)·precipitation zone time t(min) / 60.

[0057] The air flotation machine 9 is equipped with a dosing device 10. The dosing device 10 is used to inject a bioflocculant into the air flotation machine 9; the bioflocculant uses animal and plant proteins as raw materials, and is catalyzed by proteases, undergoes enzyme catalytic synthesis, and is graded and purified to eventually form an organic high molecular polymer, which has a large number of active functional groups on its molecular chain, and can effectively generate hydrogen bonds and van der Waals forces with the surface of colloidal particles in sewage, and has extremely strong adsorption, bridging and netting capabilities.

[0058] The flotation machine 9 of this embodiment is internally provided with a flotation sedimentation tank integrated at its front end, so that after the sewage enters the flotation machine 9, it can first be separated into solid and liquid in the flotation sedimentation tank, so that the heavier particles in the sewage can be deposited, and such heavier particles are prevented from entering the rear section of the flotation machine 9 to increase the workload of bottom sewage discharge, thereby effectively improving the operation effect and work efficiency of the flotation machine 9.

[0059] The water inlet of the biological digestion tank 13 is also connected to the water outlet of the buffer tank 5. By setting up the biological digestion tank 13, the clean water output by the flotation machine 9 and / or the excess clean water in the buffer tank 5 can be biologically digested to further remove harmful substances in the water body, so that the clean water can be discharged after meeting the discharge standard.

[0060] The backwash discharge port of the fiber filter 3 is connected to the sludge inlet of the sludge collecting tank 8. The fiber filter 3 has a backwash function, which can perform self-cleaning of the filter cloth and effectively extend the service life of the filter cloth.

[0061] The structure of the fiber filter 3 is as follows: it includes an outer shell, and a filter device 6 is installed inside the outer shell to filter the water in the outer shell. Figure 5-Figure 6 As shown, the structure of the filtering device 6 is: it includes at least one filter disc 601, and the outer surface of the single filter disc 601 is wrapped with fiber filter cloth; it also includes at least one connecting rod 605, one end of the single connecting rod 605 is hinged to the fixed cantilever 602, and at the same time, the other end of the single connecting rod 605 is hinged to the mud suction box 603, the mud suction box 603 is arranged one by one with the filter disc 601, and two adjacent mud suction boxes 603 are connected by a spring 604. Under the action of the spring 604, the suction nozzle of the single mud suction box 603 presses the fiber filter cloth on the corresponding filter disc 601. By setting the spring 604, the connecting rod 605 and the fixed cantilever 602, the mud suction box 603 can move with the filter disc 601, and can ensure that the mud suction box 603 always presses the corresponding filter disc 601 during the left and right swinging of the filter disc 601, so that the suction nozzle of the mud suction box 603 always presses against the fiber filter cloth on the corresponding filter disc 601, thereby ensuring that the pressing force between the suction nozzle of the mud suction box 603 and the fiber filter cloth is always balanced, ensuring the consistency of the backwashing effect of the filter disc 601, avoiding the wear of the fiber filter cloth caused by excessive force on one side, and improving the service life of the fiber filter cloth.

[0062] In this embodiment, the color of the fiber filter cloth is natural white without any special bleaching and dyeing treatment. The fiber filter cloth adopts a three-layer structure, and a three-dimensional space is set between two adjacent layers. The surface of the fiber filter cloth is densely covered with organic fiber piles, and the organic fiber piles include 50% ultrafine polyester fibers and 50% modified acrylonitrile fibers, and the polyester fiber is used as a support body; in a dry state, the fiber hairs are upright; in a wet state, the fiber hairs droop to form a filter cloth medium with an effective filtration depth of 3mm-5mm, and an equivalent pore size of 10μm; thereby, the fiber filter cloth can directly intercept and adsorb fine particles, with high filtration efficiency, low manufacturing cost, and large dirt holding capacity. It is suitable for efficient interception of high-viscosity liquids or small-diameter particles, and can be effectively used for filtering eel farming.

[0063] The clean water tank 4 is provided with an ozone generator 7 . By providing the ozone generator 7 , the clean water in the clean water tank 4 can be disinfected by passing ozone, thereby further improving the water quality of the clean water in the clean water tank 4 .

[0064] The working process of the present invention is as follows:

[0065] like Figure 2As shown, the tail water in the culture pond 1 enters the sedimentation tank body 201 through the water inlet pipe 203. Under the action of its own flow velocity and the slope 202, the water in the sedimentation tank body 201 spirally rises, so that the upper water in the sedimentation tank body 201 overflows the water weir 206 and enters the water collecting ditch 207. The water in the water collecting ditch 207 flows into the fiber filter 3 through the water outlet pipe 205, and becomes clean water after being filtered layer by layer by the fiber filter cloth on the filter disc 601. The clean water flows into the clean water tank 4, and after being disinfected by the ozone generator 7, it flows into the buffer tank 5. The clean water in the buffer tank 5 flows back to the culture pond 1 and continues to be used as culture water. If there is a lot of clean water to be reused in the buffer tank 5, the excess clean water can be introduced into the biological digestion tank 13 for further sterilization and disinfection, and then discharged after reaching the discharge standard;

[0066] The sludge in the cyclone sedimentation tank 2 enters the sewage collection tank 8 through the sewage discharge pipe 204. Under the action of the sludge pump, the sewage in the sewage collection tank 8 is lifted into the flotation machine 9. Under the action of the biological flocculant added to the flotation machine 9 by the dosing device 10, the sewage inside the flotation machine 9 is separated into solid and liquid. The upper clear liquid is introduced into the biological digestion tank 13 and is discharged after sterilization and disinfection. The lower turbid liquid is lifted into the plate and frame filter press 12 under the action of the diaphragm pump, filtered by the plate and frame filter press 12, and the obtained filtrate is led back to the sewage collection tank 8. The obtained sludge filter cake is centrally transported or composted.

[0067] Using the above-mentioned tailwater treatment system for eel farming, this embodiment provides a tailwater treatment method for eel farming, comprising the following steps:

[0068] Step 1: The tail water of the breeding pond 1 enters the cyclone sedimentation tank 2 through the first pipe group, and the cyclone sedimentation tank 2 performs sedimentation treatment on the tail water based on centrifugal force and gravity;

[0069] Step 2: The supernatant in the cyclone sedimentation tank 2 overflows into the second tube group, and is introduced into the fiber filter 3 through the second tube group for filtration and becomes clear water;

[0070] Step 3: The clean water in the fiber filter 3 flows into the clean water tank 4 through the third pipe group for recycling or direct discharge after reaching the standard.

[0071] The above description is an explanation of the present invention, not a limitation of the present invention. The scope of the present invention is defined in the claims. Any form of modification may be made within the scope of protection of the present invention.

Claims

1. A tailwater treatment system for eel farming, characterized in that: It comprises a cyclone sedimentation tank (2), the water inlet of the cyclone sedimentation tank (2) is connected to the tail water outlet of the breeding pond (1), the water outlet of the cyclone sedimentation tank (2) is connected to the water inlet of the fiber filter (3), the water outlet of the fiber filter (3) is connected to the water inlet of the clean water tank (4) through a third pipe group, the water outlet of the clean water tank (4) is connected to the water inlet of the buffer tank (5), and the water outlet of the buffer tank (5) is connected to the breeding water inlet of the breeding pond (1); The tail water in the breeding pond (1) flows into the cyclone sedimentation tank (2), and drives the water in the cyclone sedimentation tank (2) to rotate and rise, so that the upper layer of water in the cyclone sedimentation tank (2) flows into the interior of the fiber filter (3), and becomes clean water after being filtered by the fiber filter (3). The clean water flows into the clean water tank (4) and is used to supplement the breeding water of the breeding pond (1).

2. The tailwater treatment system for eel farming according to claim 1, characterized in that: The structure of the cyclone sedimentation tank (2) is as follows: it comprises a sedimentation tank body (201); a water turning weir (206) is arranged on the inner wall surface of the sedimentation tank body (201) along the circumferential direction; the water turning weir (206) is arranged obliquely, so that a water collecting ditch (207) with a decreasing width from top to bottom is formed between the wall surface of the water turning weir (206) and the inner wall surface of the sedimentation tank body (201); a water inlet pipe (203) and a water outlet pipe (205) are respectively installed on the inner wall surface of the sedimentation tank body (201); the outlet of the water outlet pipe (205) leads to the water collecting ditch (207); the water inlet pipe (203) is arranged below the water outlet pipe (205); and a slope (202) is arranged on the inner wall surface of the sedimentation tank body (201) below the water inlet pipe (203); The tail water in the culture pond (1) flows into the sedimentation tank body (201) through the water inlet pipe (203). The tail water in the sedimentation tank body (201) collides with the slope (202) under the action of its own flow velocity, thereby forming a rotating upward water flow in the sedimentation tank body (201), thereby causing the upper water body in the sedimentation tank body (201) to overflow the water overflow weir (206) and enter the water collection ditch (207). The water in the water collection ditch (207) flows into the fiber filter (3) through the water outlet pipe (205).

3. The tailwater treatment system for eel farming according to claim 2, characterized in that: A sewage outlet is provided at the center of the bottom wall of the sedimentation tank body (201); the sewage outlet is connected to the sludge inlet of the sewage collecting tank (8) through a sewage outlet pipe (204); the sewage outlet of the sewage collecting tank (8) is connected to the sewage inlet of the air flotation machine (9); the clean water outlet of the air flotation machine (9) is connected to the water inlet of the biological digestion tank (13); the scum outlet of the air flotation machine (9) is connected to the sludge inlet of the sludge tank (11); the sludge outlet of the sludge tank (11) is connected to the sludge inlet of the plate and frame filter press (12); and the sewage outlet of the plate and frame filter press (12) is connected to the sewage inlet of the sewage collecting tank (8).

4. The tailwater treatment system for eel farming according to claim 3, characterized in that: The air flotation machine (9) is equipped with a drug adding device (10).

5. The tailwater treatment system for eel farming according to claim 3, characterized in that: The backwash discharge port of the fiber filter (3) is connected to the sludge inlet of the sludge collecting tank (8).

6. The tailwater treatment system for eel farming according to claim 3, characterized in that: The water inlet of the biological digestion tank (13) is also connected to the water outlet of the buffer tank (5).

7. The tailwater treatment system for eel farming according to claim 2, characterized in that: The water inlet pipe (203) enters the interior of the sedimentation tank body (201) along a tangent line of the side wall surface of the sedimentation tank body (201).

8. The tailwater treatment system for eel farming according to claim 1, characterized in that: The structure of the fiber filter (3) is as follows: it comprises an outer shell, and a filtering device (6) is installed inside the outer shell to filter the water in the outer shell.

9. The tailwater treatment system for eel farming according to claim 8, characterized in that: The structure of the filtering device (6) is as follows: it comprises at least one filter disc (601), and the outer surface of the single filter disc (601) is wrapped with a fiber filter cloth; The invention also comprises at least one connecting rod (605), one end of the single connecting rod (605) is hinged to the fixed cantilever (602), and the other end of the single connecting rod (605) is hinged to the mud suction box (603). The mud suction boxes (603) are arranged in a one-to-one correspondence with the filter discs (601), and two adjacent mud suction boxes (603) are connected by a spring (604). Under the action of the spring (604), the suction nozzle of a single mud suction box (603) presses the fiber filter cloth on the corresponding filter disc (601).

10. A method for treating tailwater of eel farming according to claim 1, characterized in that: The steps include: The first step: the tail water of the breeding pond (1) enters the cyclone sedimentation tank (2) through the first pipe group, and the cyclone sedimentation tank (2) performs sedimentation treatment on the tail water based on centrifugal force and gravity; Step 2: The upper clear liquid in the cyclone sedimentation tank (2) overflows into the second tube group, and is introduced into the fiber filter (3) through the second tube group for filtration and becomes clear water; Step 3: The clean water in the fiber filter (3) flows into the clean water tank (4) through the third pipe group to be recycled or directly discharged after reaching the standard.

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