A device and method for treating factory aquaculture tail water using monocyclic spiny worms

Abstract

A device and method for treating factory aquaculture tailwater using Echinops monocylindrica belongs to the technical field of aquaculture tailwater treatment. The method uses Echinops monocylindrica to treat factory aquaculture tailwater in a sand filter; the sand filter body is divided into three layers by a sea intestine aquaculture box support screen plate, a coarse sand screen, and a pebble screen, namely a fine sand layer, a coarse sand layer, and a pebble layer. The fine sand layer is divided into four fan-shaped sea intestine aquaculture boxes for aquaculture of Echinops monocylindrica. The method utilizes the sea intestine's own absorption of bait residues in the aquaculture tailwater, as well as the silt to filter large particles in the aquaculture tailwater. The method organically integrates mechanical, microbial, and biological methods to purify aquaculture tailwater, which is relatively time-saving and labor-saving. It is suitable for filtering natural seawater or factory and pond seedling and aquaculture tailwater, and has a wide range of applications; it improves the utilization rate and output rate of unit seawater resources and avoids the waste of water resources.

Description

Technical Field

[0001] The present invention relates to a device and method for treating industrial aquaculture tailwater using sea cucumber (sea cucumber), belonging to the technical field of aquaculture tailwater treatment. The device is primarily aimed at the primary treatment of industrial aquaculture tailwater from seawater, as well as the reuse of residual bait and feces in the tailwater. It has applications in industrial and pond breeding and aquaculture of marine economic organisms, as well as in the desalination industry and large-scale seawater aquarium industry. Background Art

[0002] With the increasingly vibrant development of the marine economy and technology, seawater resources are becoming increasingly valuable. A consensus is emerging on the efficient, energy-saving, environmentally friendly, and ecological utilization of seawater resources. Factory-based, large-scale aquaculture production is currently a major development trend. The reuse of seawater in land-based factory aquaculture has led to eutrophication, a problem that urgently needs to be addressed. Under factory-based, intensive aquaculture, high-density feed residues in seawater aquaculture can lead to excessively high levels of organic matter, nitrogen, and phosphorus in the water. Furthermore, domestic aquaculture technology is not yet industrialized. The indiscriminate discharge of aquaculture tailwater will exacerbate eutrophication in coastal waters and easily pollute the marine environment.

[0003] Currently, water purification technology in my country primarily relies on physical (precipitation, filtration, foam separation), chemical (oxidation-reduction, flocculation), and biological (biotransformation, biodegradation) methods to purify aquaculture water to meet the needs of industrial aquaculture. However, in roadbed industrial aquaculture plants, the water treatment technologies currently used still present various challenges. For example, the use of chemical agents can easily cause secondary contamination of aquaculture water; physical filtration is ineffective in removing soluble organic and inorganic matter, total nitrogen, and total phosphorus; and while biological treatment offers ecological and safety advantages, it suffers from long treatment cycles and slow effectiveness. Newer water treatment technologies, such as membrane technology, ozone oxidation, and improved biofilter media, often come with high costs and variable filtration performance. Membrane technology is expensive, has a short lifespan, and is susceptible to contamination and scaling. Ozone oxidation is expensive and expensive to process, lacks selectivity, and is less effective against certain halogenated hydrocarbons and pesticides. Improved biofilter media are also expensive and have low utilization rates.

[0004] Specifically, in industrialized marine aquaculture, residual bait can pollute the water. Current technologies for treating aquaculture tailwater using mechanical, physical, biological, and chemical methods often struggle to achieve the desired results or are prohibitively expensive. Therefore, the technical challenges addressed in this application are how to treat this tailwater, which is rich in aquatic organic matter, nutrients such as nitrogen and phosphorus, at low cost and with high returns, or how to utilize it during the treatment process. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a method for treating factory aquaculture tailwater using Echinops monocylindrica (sea cucumber), which is cultured in a sand filter tank to pre-treat the aquaculture tailwater. The Echinops monocylindrica has a strong ability to adapt to the seawater environment and has the characteristics of improving water quality, which makes it less likely for the Echinops monocylindrica to become ill during the aquaculture process; at the same time, the culture of Echinops monocylindrica also has a certain water permeability, which increases the water permeability of the sand filter tank and avoids the problem of the existing sand filter tank needing to be sealed and pressurized due to poor water permeability; finally, the culture of Echinops monocylindrica in the sand filter tank can effectively absorb and utilize aquatic organic matter, N and P and other nutrients in the seawater aquaculture tailwater, avoiding the problem of eutrophication caused by the direct discharge of the tailwater; thus, the aquaculture tailwater can be treated at a low cost and with high returns.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0007] A single-ring spiny worm sand filter, wherein the bottom of the sand filter is supported by legs, a water inlet pipe is provided on the top, and a sand filter body is provided inside. A hollow overflow layer and an outer protective layer are provided on the outside of the sand filter body in sequence, a tank body protective cover is provided above the outer protective layer, and the tank body protective cover is provided with a protective cover vent; an overflow siphon is provided at the bottom of the hollow overflow layer, the highest point of the overflow siphon is lower than the upper edge of the sand filter body; an alarm controller is provided on the overflow siphon; load-bearing pillars are provided between adjacent layers of the sand filter body, the hollow overflow layer, and the outer protective layer;

[0008] The sand filter body is divided into three layers by the sea intestine breeding box support screen plate, coarse sand screen and pebble screen, which are respectively a fine sand layer, a coarse sand layer and a pebble layer; a water distributor is provided at the bottom of the water inlet pipe, and the water distributor is suspended above the fine sand layer; the lower side of the pebble screen and the bottom of the sand filter body form a water collecting chamber, and a load-bearing pillar is provided in the water collecting chamber, and its two ends are respectively connected to the pebble screen and the sand filter body; a prismatic fixing column is provided at the center above the pebble screen, and the prismatic fixing column passes through the coarse sand screen, the coarse sand layer and the sea intestine breeding box support screen plate in sequence and extends to the fine sand layer; one end of the porous drainage pipe is connected to the center below the pebble screen, and the drainage pipe passes through the sand filter body, the hollow overflow layer and the outer protective layer in sequence and is provided with a water outlet at the other end, and the part of the porous drainage pipe placed in the water collecting chamber is provided with a drainage hole;

[0009] The fine sand layer adopts a plurality of fan-shaped sea intestine breeding boxes arranged with a prismatic fixed column as the center. The fan-shaped sea intestine breeding boxes adopt an arc plate, a prismatic flat plate and a screen partition to form a fan-shaped structure. A bottom screen plate is provided at the bottom of the fan-shaped sea intestine breeding box, and an arc-shaped guard plate folded to the upper edge of the sand filter tank body is provided on the arc plate; and a lifting lug for lifting is provided on the arc-shaped guard plate.

[0010] A method for treating factory aquaculture tail water using Spinella unicinctum, wherein the method is to cultivate Spinella unicinctum in the above-mentioned sand filter tank to treat the factory aquaculture tail water; the method specifically comprises the following steps:

[0011] a. Cultivate the juvenile or adult larvae of the single-ringed spiny moth in fan-shaped sea intestine culture boxes, with the number of adult larvae cultured being 200 to 250 per cubic meter. 2 The number of juveniles cultured is 3500 to 4500 per m 2 The fine sand filter material occupies 5 / 6 of the height of the fan-shaped sea intestine culture box, and the upper layer reserves space for overlying water; the fine sand layer filter material uses sea sand with a particle size of 0.8-1.2mm;

[0012] b. The aquaculture tailwater flows through the water inlet pipe and the water distributor into the fine sand layer of the sand filter. At this time, the monocypripedium in the fan-shaped sea intestine culture tank absorbs nutrients in the aquaculture tailwater; at the same time, the fine sand layer filters the aquaculture tailwater;

[0013] c. After passing through the fine sand layer, the aquaculture tail water passes through the bottom sieve plate and the sea intestine aquaculture box support sieve plate in sequence and enters the coarse sand layer for filtration; after passing through the coarse sand layer, the aquaculture tail water passes through the coarse sand screen and enters the pebble layer, and then passes through the pebble screen and enters the water collection chamber;

[0014] d. The water in the water collection chamber enters the perforated drain pipe through the drainage hole and is discharged from the outlet;

[0015] e. When the hydraulic load of the sand filter is overloaded, the aquaculture tail water will overflow into the hollow overflow space, and the bottom of the hollow overflow layer will flow to the next sand filter or sewage collection tank through the overflow siphon;

[0016] f. An overflow siphon with an alarm controller is installed on the last-stage sand filter. The alarm controller can control the start and stop of water inlet from the water inlet pipe. When the alarm controller detects water flow, the water inlet from the water inlet pipe is stopped; when the alarm controller detects no water flow, the water inlet from the water inlet pipe is opened.

[0017] g. When the outlet of the overflow siphon is connected to the sewage collection tank, the aquaculture tail water is blocked by the sewage collection tank partition when it is discharged into the sewage collection tank, so that the impurities in the aquaculture tail water before the sewage collection tank partition are settled; the aquaculture tail water behind the sewage collection tank partition is discharged from the drainage outlet of the sewage collection tank after sedimentation.

[0018] The tank protective cover is provided with a protective cover vent. A water distributor is provided at the bottom of the water inlet pipe, and the water distributor is suspended above the fine sand layer. The outlet of the overflow siphon is connected to the sewage collection tank, and the outlet position of the overflow siphon is set at 2 / 3 of the height of the tank wall. The outlet of the overflow siphon is connected to the water inlet pipe of the next sand filter, and multiple sand filters are connected in series; the outlet of the overflow siphon of the last sand filter is connected to the sewage collection tank, and the outlet position of the overflow siphon is set at 2 / 3 of the height of the tank wall. A sewage collection tank partition is provided in the sewage collection tank, and the distance from the sewage collection tank partition to the tank wall connected to the overflow siphon outlet is 2 / 3 of the length of the tank bottom; the height of the sewage collection tank partition is 2 / 3 of the height of the tank wall. An alarm controller for monitoring the water level and alarming is provided on the overflow siphon. Lifting lugs for hoisting are provided on the curved guard plate.

[0019] The sand filter tank consists of a water inlet and a water distribution device. The upper sea cucumber culture tank is equipped with a fine sand layer suitable for the survival of monocyprids and a bottom screen. The middle interlayer is equipped with a coarse sand layer and a bottom screen. The lower interlayer is equipped with a cobblestone layer and a bottom screen. To address the load-bearing capacity of the inner sea cucumber culture tank, 6-8 support columns are designed at the bottom to secure and support the inner sea cucumber culture tank. The bottom adopts a solid bottom structure and reserves water outlet pipes. When the inner sea cucumber culture tank is overloaded, the water overflows from the upper space into the middle overflow space. 6-8 support columns are also installed at the bottom of the middle overflow space to secure and support the inner sea cucumber culture tank. The bottom of the middle overflow space is equipped with a drainage pipe and an overflow siphon. A small sensor is designed on the overflow siphon to detect the sewage discharge from the overflow space. The outer space is a protective layer, designed to protect the inner sea cucumber culture tank from external natural factors. The present invention can be connected in parallel or series to form a biological treatment project for marine aquaculture tailwater.

[0020] The water inlet is connected to the water distribution device, which adopts a porous water distribution method to prevent the hydraulic flow rate from causing sediment loss; the aquaculture tail water flows from the water distribution device into the upper sea intestine aquaculture box, and the monocyclic spiny worms are used to absorb the bait residue in the aquaculture tail water, and the sediment is used to physically filter the harmful factors in the aquaculture tail water; a screen device is set at the bottom, and the screen mesh is smaller than the size of the sediment particles to prevent sediment loss and filter the aquaculture tail water; the aquaculture tail water is filtered in the upper sea intestine aquaculture box and absorbed by the sea intestine and flows into the coarse sand layer, and a screen is set at the bottom After being filtered through the coarse sand layer, the aquaculture tailwater flows into the pebble layer, at the bottom of which a screen is set; 6-8 support columns are set at the bottom of the screen in the pebble layer to fix and support the inner layer of sea intestine aquaculture boxes; the aquaculture tailwater flows through the pebble layer into the water outlet at the bottom of the sea intestine aquaculture box, and the water outlet connects the middle overflow space to the bottom of the outer protective layer; when the hydraulic load of the inner sea intestine aquaculture box space is overloaded, the aquaculture tailwater overflows from the upper layer to the middle overflow space; 6-8 support columns are set at the bottom of the overflow space to fix and support the inner layer of sea intestine aquaculture boxes;

[0021] An overflow siphon is installed at the bottom of the overflow space, with a small sensor switch attached to it. Six to eight support columns are installed at the bottom of the outer space to secure and support the inner sea cucumber aquaculture tanks. An outlet is designed at the bottom of the outer space to drain the aquaculture tailwater. Materials used for this device include, but are not limited to, PVC, concrete, fiberglass, titanium alloy, and reinforced concrete.

[0022] The beneficial effects of the present invention are as follows: the sand filter includes a sand filter body, a hollow overflow layer and an outer protective layer. The sand filter body is divided into three layers through the sea intestine breeding box support screen plate, the coarse sand screen and the pebble screen, namely the fine sand layer, the coarse sand layer and the pebble layer. The fine sand layer is divided into 4 fan-shaped sea intestine breeding boxes, the sides and bottom of which are both permeable screens; the top plate of the fan-shaped sea intestine breeding box is provided with an arc-shaped guard plate, which is folded at the upper edge of the sand filter body for overflow drainage. The aquaculture tail water is subjected to primary treatment by the sand filter, and the bait residue in the aquaculture tail water is absorbed by the sea intestine itself, and the large particles in the aquaculture tail water are filtered by the sediment; it is intended to realize the purification of the water body by utilizing biological absorption, physical filtration, microbial biochemical reaction and other aspects, and to enable the effective multiple use of water resources to avoid the waste of water resources.

[0023] It has a certain effect on removing bait residues and harmful factors in the tail water of marine aquaculture. In addition, it increases the output of aquaculture species in the process of marine aquaculture, aiming to improve the utilization rate and output of unit water bodies, and provide marine aquaculture industry with a more environmentally friendly, effective and more ecologically demand-oriented technical link.

[0024] In view of the technical means currently used in water treatment technology and the ecological habits of the monocyclic moth, the present invention combines the rational matching of aquatic organisms and physical and mechanical technologies, and utilizes the effect of the monocyclic moth itself on improving water quality on the basis of the water quality treatment mechanism to treat aquaculture tail water.

[0025] The sand filter is designed to filter natural seawater or tail water from factory-based and pond-based seedling and aquaculture, thereby increasing the utilization rate and output rate of unit seawater resources, achieving efficient, energy-saving, environmentally friendly and ecological utilization of seawater resources, and making corresponding contributions to the aquatic products industry.

[0026] The organic combination of technologies from three different fields, namely mechanical, microbial and biological, achieves a whole process for purifying aquaculture tail water, which is more time-saving and labor-saving. It is suitable for filtering natural seawater or factory and pond seedling and aquaculture tail water, and has a wide range of applications. It improves the utilization rate and output rate of unit seawater resources, achieves efficient, energy-saving, environmentally friendly and ecological utilization of seawater resources, and avoids the waste of water resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1It is a structural diagram of a single-ring spiny sand filter.

[0028] Figure 2 It is a cross-sectional view of a single-ring spiny sand filter.

[0029] Figure 3 yes Figure 2 Cross-sectional view of AA in the figure.

[0030] Figure 4 It is a working diagram of a single-ring spiny sand filter.

[0031] Figure 5 This is a graph showing the flow rate changes of seawater and tailwater in two filter materials (sea sand and river sand), with different particle sizes and thicknesses.

[0032] Figure 6 This is a graph showing the salinity changes of seawater and tailwater in two filter materials (sea sand and river sand), with different particle sizes and thicknesses.

[0033] Figure 7 This is a graph showing the pH changes of seawater and tailwater in two filter materials (sea sand and river sand), with different particle sizes and thicknesses.

[0034] Figure 8 This is a graph showing the changes in dissolved oxygen in seawater and tailwater when using two filter materials (sea sand and river sand), with different particle sizes and thicknesses.

[0035] Figure 9 This is the conductivity change diagram of seawater and tail water when using two filter materials (sea sand and river sand), different particle sizes and different thicknesses.

[0036] Figure 10 This is a graph showing the changes in dissolved solids in seawater and tailwater when using two filter materials (sea sand and river sand), different particle sizes, and different thicknesses.

[0037] Figure 11 This is a diagram showing the effect of mesh size on deformation.

[0038] Figure 12 It is a cloud diagram of the simulation results of the fine sand layer in the assembled state and a thickness stress curve of the aquaculture box material.

[0039] Figure 13 It is a cloud diagram of the simulation results of the fine sand layer in the separated state and a thickness stress curve of the aquaculture box material.

[0040] Figure 14 It is the cloud map of the simulation results of the fine sand layer and the thickness stress curve.

[0041] Figure 15 It is the cloud map of the simulation results of the coarse sand layer and the thickness stress curve.

[0042] Figure 16 It is the cloud map of the simulation results of the pebble layer and the thickness stress curve.

[0043] Figure 17 It is a cloud diagram of the simulation results of the overall internal structure after assembly.

[0044] Figure 18 This is the treatment effect of the monocyclic moth on aquaculture tail water.

[0045] In the figure: 1, water inlet pipe, 1a, water distributor, 2, tank protective cover, 2a, protective cover vent, 3, fine sand layer, 3a, fan-shaped sea intestine culture box, 3b, curved plate, 3c, screen partition, 3d, prismatic flat plate, 3e, curved guard plate, 3f, bottom screen, 3g, lifting ear, 4, culture box support screen plate, 5, coarse sand layer, 6, coarse sand screen, 7, pebble layer, 8, pebble screen, 9, water collection chamber, 10, porous drain pipe, 10a, drainage hole, 11, hollow overflow layer, 12, overflow siphon, 13, outer protective layer, 14, load-bearing pillar, 15, water outlet, 16, alarm controller, 17, support leg, 18, sand filter body, 19, sewage collection tank, 19a, sewage collection tank partition, 19b, pool wall, 19c, pool bottom, 20, prismatic fixing column. DETAILED DESCRIPTION

[0046] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0047] Example 1 Structure of sand filter

[0048] Figures 1 to 3 A single-ring spiny worm sand filter is shown. The bottom of the sand filter is supported by legs 17, a water inlet pipe 1 is provided on the top, and a sand filter body 18 is provided inside. The characteristics are as follows: a hollow overflow layer 11 and an outer protective layer 13 are provided in sequence on the outside of the sand filter body 18, and a tank protective cover 2 is provided above the outer protective layer 13; an overflow siphon 12 is provided at the bottom of the hollow overflow layer 11, and the highest point of the overflow siphon 12 is lower than the top of the sand filter body 18; and load-bearing pillars 14 are provided between adjacent layers of the sand filter body 18, the hollow overflow layer 11 and the outer protective layer 13.

[0049] The sand filter body 18 is divided into three layers by the sea intestine breeding box support screen plate 4, the coarse sand screen 6 and the pebble screen 8, namely the fine sand layer 3, the coarse sand layer 5 and the pebble layer 8; the lower side of the pebble screen 8 and the bottom of the sand filter body 18 form a water collection chamber 9, and a load-bearing pillar 14 is provided in the water collection chamber 9, and its two ends are respectively connected to the pebble screen 8 and the sand filter body 18; a prismatic fixing column 20 is provided at the upper center of the pebble screen 8, and the prismatic fixing column 2 passes through the coarse sand screen 6, the coarse sand layer 5 and the sea intestine breeding box support screen plate 4 in sequence and extends to the fine sand layer 3; one end of the porous drainage pipe 10 is connected to the lower center of the pebble screen 8, and the drainage pipe 10 passes through the sand filter body 18, the hollow overflow layer 11 and the outer protective layer 13 in sequence. The other end is provided with a water outlet 15, and the part of the porous drainage pipe 10 placed in the water collection chamber 9 is provided with a drainage hole 10a.

[0050] The fine sand layer 3 adopts four fan-shaped sea intestine culture boxes 3a arranged with a prismatic fixed column 20 as the center. The fan-shaped sea intestine culture box 3a adopts an arc plate 3b, a prismatic flat plate 3d and a screen partition 3c to form a fan-shaped structure. A bottom screen plate 3f is set at the bottom of the fan-shaped sea intestine culture box 3a; a curved guard plate 3e is set on the curved plate 3b and folded onto the sand filter body 18.

[0051] The tank protective cover 2 is provided with a protective cover vent 2a for ventilation of sand sausage culture. A water distributor 1a is provided at the bottom of the water inlet pipe 1, and the water distributor 1a is suspended above the fine sand layer 3. The outlet of the overflow siphon pipe 12 is connected to the sewage collection tank 19, and the outlet position of the overflow siphon pipe 12 is set at 2 / 3 of the height of the tank wall 19b. Alternatively, the outlet of the overflow siphon pipe 12 is connected to the water inlet pipe of the next sand filter, and multiple sand filters are connected in series; the outlet of the overflow siphon pipe 12 of the last sand filter is connected to the sewage collection tank 19, and the outlet position of the overflow siphon pipe 12 is set at 2 / 3 of the height of the tank wall 19b.

[0052] A sewage collection tank partition 19a is installed within the sewage collection tank 19. The distance from the sewage collection tank partition 19a to the tank wall 19b connected to the outlet of the overflow siphon 12 is two-thirds the length of the tank bottom 19c; the height of the sewage collection tank partition 19a is two-thirds the height of the tank wall 19b. An alarm controller 16 is installed on the overflow siphon 12 to monitor the water level and generate an alarm. Lifting lugs 3g are provided on the curved guard plate 3e for lifting.

[0053] When using the above technical solution, aquaculture wastewater first flows into the sand filter tank 18 through the water inlet 1. A ventilation device is designed for the tank protective cover 2 to ensure the required light level for the survival of the sea cucumber culture tanks within the tank, and to allow the aquaculture tailwater to undergo biochemical reactions through air contact. The sand filter tank 18 is divided into three layers: upper, middle, and lower. The fine sand layer 3 is the sandy and muddy substrate for cultivating sea cucumbers. A prismatic fixed column 20 is installed in the center of the tank. The fine sand layer 3 is divided into four equal fan-shaped sea cucumber culture tanks 3a, centered on the column. Each fan-shaped structure has a solid curved plate 3b, and the cross-section screen partition 3c and the bottom screen plate 3f are mesh structures. The prismatic plane 3d interacts with the prismatic fixed column 20. The main function of the bottom screen plate 3f is to prevent sediment from being lost with the water flow. A sea cucumber culture tank support screen plate 4 is installed at the bottom of the bottom screen plate 3f to support the fan-shaped sea cucumber culture tanks 3a. After passing through the bottom sieve plate 3f and the sea cucumber aquaculture tank support sieve plate 4, the aquaculture tailwater seeps into the coarse sand layer 5. To prevent the loss of coarse sand due to gravity, a coarse sand screen 6 is installed at the bottom of the coarse sand layer 5. The aquaculture tailwater continues downward into the pebble layer 7, which also has a pebble screen 8 at the bottom to prevent pebbles from falling. Finally, the aquaculture tailwater enters the water collection chamber 9. By providing a buffer space for the aquaculture tailwater to contact air, the water collection chamber 9 is connected to a porous drain pipe 10 to facilitate the discharge of the filtered aquaculture tailwater, preventing the loss of sediment.

[0054] When the sand filter body 18 is hydraulically overloaded, the aquaculture tail water will overflow into the middle overflow space. An overflow siphon 12 is provided on the right side of the drainage pipe at the bottom of the middle overflow space. The overflow siphon 12 will flow the overflowed aquaculture tail water to the next sand filter or sewage collection tank 19.

[0055] The sand filter is protected by an outer protective layer 13, which protects the internal hollow overflow layer 11 and sand filter body 18. Load-bearing support columns 14 are located at the bottom of the pebble screen 9, sand filter body 18, and hollow overflow layer 11 to ensure they can support the weight of the sand and gravel structure and the aquaculture tailwater throughout the water purification process.

[0056] A water outlet 15 is provided at the bottom of the sand filter tank. The length of the water outlet pipe passes through the hollow overflow layer 11 and the outer protective layer 13 and is connected to the porous drainage pipe.

[0057] Example 2 Treatment method for aquaculture tail water

[0058] The method specifically comprises the following steps:

[0059] a. Cultivate the seedlings of the single-ringed spiny caterpillar in a fan-shaped sand intestine pond, with a breeding quantity of 200 to 250 heads / m 2 , the fine sand filter material is filled to 5 / 6 of the height, and the upper layer is reserved for overlying water space; the fine sand layer filter material is selected from sea sand with a particle size of 0.8-1.2mm;

[0060] b. The aquaculture tail water passes through the water inlet pipe 1 and the water distributor 1a into the fine sand layer 3 of the sand filter body 18. At this time, the monocyprids in the fan-shaped sea intestine aquaculture box 3a absorb the nutrients in the aquaculture tail water; at the same time, the fine sand layer 3 filters the aquaculture tail water;

[0061] c. After passing through the fine sand layer 3, the aquaculture tail water passes through the bottom sieve plate 3f and the sea intestine aquaculture box support sieve plate 4 in sequence, and enters the coarse sand layer 5 for filtration; after passing through the coarse sand layer 5, the aquaculture tail water passes through the coarse sand screen 6 and enters the pebble layer 7, and then passes through the pebble screen 8 and enters the water collection chamber 9;

[0062] d. The water in the water collecting chamber 9 enters the porous drain pipe 10 through the drainage hole 1a and is discharged from the water outlet 15;

[0063] e. When the sand filter body 18 is hydraulically overloaded, the aquaculture tail water will overflow into the hollow overflow space, and the bottom of the hollow overflow layer 11 will flow to the next sand filter or sewage collection tank 19 through the overflow siphon 12;

[0064] f. An overflow siphon 12 with an alarm controller 16 is provided on the last-stage sand filter. The alarm controller 16 can control the start and stop of water inlet into the water inlet pipe 1. When the alarm controller 16 detects water flow, the water inlet into the water inlet pipe 1 is stopped; when the alarm controller 16 detects no water flow, the water inlet into the water inlet pipe 1 is opened;

[0065] g. When the outlet of the overflow siphon 12 is connected to the sewage collecting tank 19, the aquaculture tail water is blocked by the sewage collecting tank partition 19a when it is discharged into the sewage collecting tank 19, so that the impurities in the aquaculture tail water before the sewage collecting tank partition 19a are settled; the aquaculture tail water behind the sewage collecting tank partition 19a is discharged from the drain outlet of the sewage collecting tank after sedimentation.

[0066] Example 3 Sand filter media performance screening and water purification test

[0067] The sand filter body is divided into three layers through the sea intestine culture box support screen plate, coarse sand screen and pebble screen, namely fine sand layer, coarse sand layer and pebble layer. The filter material selected for the fine sand layer of the sand filter must not only meet the survival, growth and living conditions of the monocyclic spiny worm, but also meet the water filtration rate requirements of the sand filter. This method studies the filtration performance of sea sand and river sand with a particle size range of 0.3mm-2mm, using a certain natural seawater and (brown flounder) aquaculture tail water as test water. By selecting different filter materials, the filtration performance of different particle sizes, the water filtration rate, the thickness of the filter material and other aspects on the flow rate, flow velocity and water quality, the filter material most suitable for the working requirements of the sand filter is screened out after comparison, and the optimal process parameters are determined.

[0068] The flow rate and velocity measurements for different particle sizes and thicknesses were divided into a seawater (W) series and a tailwater (E) series. The tests were conducted using seawater (W) first, followed by tailwater (E), and sea sand (SP) first, followed by river sand (RP). Each filter media was tested in five thickness gradients, in the order of 30 cm (H1), 40 cm (H2), 50 cm (H3), 60 cm (H4), and 70 cm (H5). The test groups are shown in Table 1.

[0069] Table 1 Comparison of test groups and numbers

[0070]

[0071] Each set of experimental measurement parameters includes flow rate, flow rate, and water quality physical and chemical indicators. These include salinity (SAL), pH, dissolved oxygen (DO), conductivity (CT), total dissolved solids (TDS), temperature, and oxidation-reduction potential (ORP).

[0072] 1. Selection of sand filter media particle size

[0073] When the filter material particle size is 0.3-0.5mm, 0.5-0.8mm, 0.8-1.2mm, 1.2-1.6mm, 1.6-2.0mm, the filtration rate interval values ​​are 0.19-0.36m / h, 0.27-0.75m / h, 1.13-2.72m / h, 2.12-4.12m / h, 3.42-7.02m / h respectively (see Table 2). Figure 5 It can be seen that as the particle size increases, the filtration rate increases; and as the filter material thickness increases, the filtration rate decreases. When the filter material particle size is 0.3-0.8mm (filtration rate is 0.19-0.36m / h), the slow filtration (0.1m / h-0.3m / h) requirement is achieved.

[0074] Rapid filtration (5-7 m / h) is achieved when the particle size is 1.6-2.0 mm (filtration rate 3.42-7.02 m / h). The growth of E. monocygnus is optimal when the particle size of its substrate is 40-60 mesh, but E. monocygnus is highly adaptable and can survive in environments with particle sizes slightly larger than its optimal substrate size. The selection of filter media for sand filters requires consideration of factors such as the sand filtration process, recirculating aquaculture model, and the E. monocygnus's growth environment. Therefore, filter media with a particle size of 0.8-1.2 mm is preferred for sand filters.

[0075] Table 2 Flow rate results of each test group (m / h)

[0076]

[0077] 2. Water quality indicators affect the selection of sand filter media

[0078] 2.1 Salinity (SAL)

[0079] The salinity variation range of the sea sand group is smaller than that of the river sand group (see Table 3, Figure 6 This is likely because the sea sand itself is already saturated with seawater, so during the experiment, it did not absorb or retain salinity from the seawater. Both recirculating aquaculture and the temporary culture of E. monocyrthosiphon in sand filters require a stable salinity environment, so sea sand performs better than river sand in response to salinity fluctuations.

[0080]

[0081] 2.2 pH

[0082] The pH value range during this experiment was 8.25-7.7 (see Figure 7 ). The pH range of the sea sand group was smaller than that of the river sand group. This may be because, in natural environments, sea sand is eroded by seawater, and the pH of its surface layer is similar to that of seawater. River sand, on the other hand, is washed by freshwater, and its surface pH should be more consistent with that of freshwater. Furthermore, seawater was used as the test water in this experiment, so the pH of the sea sand group showed less variation than that of the river sand group. Sea sand has a more stable pH when treating seawater than river sand. Therefore, sea sand is a more preferred filter media for recirculating seawater aquaculture or sand filter tanks.

[0083] 2.3 Dissolved oxygen (DO)

[0084] DO is the basic condition for the survival of aquaculture. Its change depends on the background value of the test raw water. In this experiment, the DO range was 11.55±0.66-9.22±0.03 mg / L. When the DO range was 9.6-11.5 mg / L, the DO value of both the sea sand group and the river sand group showed a downward trend (see Figure 8 ); however, when the DO value is less than 9.5 mg / L, after filtration, the DO value will float upward, with a variation range of 0.1-0.2 mg / L. This may be because when seawater is pumped into the laboratory under a natural environment, the DO value of seawater remains between 10.4-11.5 mg / L for a short period of time. After entering the test environment, the DO value in the seawater has been in a declining state; during tail water treatment, the DO value in the tail water is less than 9.5 mg / L, and the water body comes into contact with the air in the sand particles during the sand filtration process, which increases the oxygen content of the water body. In the process of recirculating aquaculture, the DO content in the water will be increased by oxygenation. Therefore, when selecting filter media for sand filters, the DO value cannot be used as a criterion for measuring filter media selection.

[0085] 2.4 Conductivity (CT)

[0086] During the test, the CT range was 49.54±0.44-44.11±0.3S / m. As the particle size increased, the treatment effect of sea sand was better than that of river sand (see Figure 9 ). At 0.3-0.8mm, the CT treatment effect of the river sand group was better than that of the sea sand group, but at 0.8-2.0mm, the CT treatment effect of the sea sand group was significantly better than that of the river sand group. The reason for this situation may be that when the filter media particle size is 0.8-2.0mm, the proportion of fine sand in the sea sand group is greater than that of the river sand. Therefore, when the filter media particle size is in the range of 0.8-2.0mm, the treatment effect of the sea sand group is better than that of the river sand group. During the water treatment process, a lower CT value represents a better water treatment effect. According to the consideration of the filter media filtration rate, the filtration rate reaches the requirements of the sand filtration process when the filter media particle size is in the range of 0.8-2.0mm. Therefore, in the CT index treatment, although the CT treatment effect of the river sand group is better than that of the sea sand group when the particle size is 0.3-0.8mm, considering the filtration rate, it is more inclined to the 0.8-2.0mm filter media CT treatment result that meets the filtration rate requirements. Therefore, in the case of sand filter tank treatment, sea sand is more inclined to be selected.

[0087] 2.5 Total dissolved solids (TDS)

[0088] The change in TDS value is positively correlated with the change in CT value. The TDS in seawater is generally 32000 mg / L. During this experiment, the CT change range was 32223.8±159.2-28089.2±4.4 mg / L. As the particle size increases, the treatment effect of sea sand is better than that of river sand. At 0.3-0.8 mm, the treatment effect of the river sand group on TDS value is significantly better than that of the sea sand group, but at 0.8-2.0 mm, the treatment effect of the sea sand group on TDS value is significantly better than that of the river sand group (see Figure 10 ). The reason for this situation may be consistent with the reason for the above CT value. In summary, during this test, the two filter media selected, sea sand and river sand, have most of the performances of sea sand filter media better than river sand filter media. The two filter media have the best water filtration effect when the particle size is 0.3-0.5mm, but the filtration rate is the slowest, so the sea sand and river sand of this particle size cannot be used as sand filter media. When the particle size is 0.5-0.8mm, both filter media meet the slow filtration requirements, but in the actual production process, the filtration rate requirements are higher, and the filter media with a particle size of 0.5-0.8mm cannot fully cooperate with the diversified production conditions. The particle size of 1.6-2.0mm has the fastest filtration rate, but compared with 0.3-1.6mm, the water filtration effect is slightly worse. It can be used as a coarse sand layer filter material to increase the filtration rate of the sand filter. In the actual production process, the filtration rate is fastest when the particle size is 0.8-1.2mm. Although the filtration performance is slightly worse than that of 0.2-0.5mm and 0.5-0.8mm particle sizes, it can meet diversified production conditions. Therefore, the selection of sand filter media is more inclined to choose 0.8-1.2mm sea sand.

[0089] Overall, this test can provide detailed information on water quality and filter media performance under different conditions, which helps to optimize the selection and use of filter media, improve the efficiency and water quality of water treatment systems, and provide basic data support for the selection of actual filter media in sand filter operations.

[0090] Example 4: Stress Analysis and Optimization of the Internal Structure of the Sand Filter

[0091] According to the structural design of the sand filter, the internal structural pressure of the sand filter is simulated, mainly studying and analyzing the stress changes of the internal structural materials of the sand filter. According to the simulation results, the structural parameters are optimized, the optimal values ​​are obtained, and the various structures are assembled to form the sand filter.

[0092] 1. Design and calculation of sand filter structural parameters

[0093] Through the sand filter material test and sand filter structure construction, the sand filter structure parameters are designed as follows (see Table 4):

[0094] Table 4 Structural design parameters of each component of the sand filter, and calculation results of volume and internal volume

[0095]

[0096] Based on the obtained structural volume and internal volume of the sand filter and the material mass, the quality parameters of the sand filter are obtained. According to the literature, the bulk density of sea sand, river sand, and pebbles are: 1.60g·cm -3 , 1.65 g·cm -3 , 2.66 g·cm -3 Based on the weight calculation results of the internal structure of the sand filter, the gravity and pressure of each structure are calculated, and the results are shown in Table 5.

[0097] Table 5 Calculation results of weight and pressure of sand filter

[0098]

[0099] 2. Pool structure parameter design and calculation

[0100] The internal structural pressure of the sand filter was simulated using the static structural analysis module of ANSYS Workbench 2021R1. A 3D model of the sand filter was created in SolidWorks 2018 and imported into Workbench as the static analysis geometry. Material parameters were then designed in the Workbench database. Since sand filters are used for tailwater treatment in aquaculture, which includes both freshwater and marine aquaculture, PVC was selected as the material, considering the potential for secondary contamination during the treatment process. This material was then set as PVC in Workbench.

[0101] 2.1 Grid independence verification

[0102] In order to ensure the credibility of the simulation results, the number of grid divisions and the number of simulation iterations were verified to be independent of each other. For the calculation model of the pebble layer of the sand filter, the maximum deformation was used as the monitoring indicator, and a grid number of 3.6×10 4 ~3×10 5 There are five different calculation schemes within the range, as shown in Table 6 below. The calculation settings of the five schemes are all the same, and the calculation results are as follows Figure 11 shown.

[0103] Table 6 Grid division scheme

[0104]

[0105] When the number of mesh divisions reaches 1282876 (Scheme 3) or more, Scheme 5 is used as the calculation basis. The deformation error is less than 0.5%. Considering the calculation accuracy and efficiency, Scheme 3 is selected. The mesh division process uses a Y-type grid with a grid unit size of 6 mm.

[0106] 2.2 Static stress simulation of fan-shaped breeding box structure

[0107] The stresses on fan-shaped culture boxes during sand filtration of aquaculture tailwater are divided into two states: assembled and separated. The assembled state refers to when the fan-shaped culture boxes serve as the primary treatment module in the sand filter, with four boxes placed in the fine sand layer of the sand filter. The stress is primarily applied to the bottom sieve plate. The separated state refers to when the larvae of the single-ringed worms mature or the fine sand in the culture boxes needs to be replaced. At this time, the fan-shaped culture boxes need to be removed from the fine sand layer of the sand filter to collect the finished single-ringed worms or replace the fine sand. The stress is primarily applied to the bottom sieve plate of the culture box, with additional stress applied to the sides and fan-shaped surfaces.

[0108] (1) Assembly status

[0109] The fine sand layer is divided into 4 fan-shaped breeding boxes. The pressure of the screen surface at the bottom of each fan-shaped breeding box is 3184.9Pa. The fan-shaped surface and the side relationship are set as fixed supports. According to the simulation results, the maximum total deformation of the screen plate at the bottom of the fan-shaped breeding box after the force is applied is 0.57893mm, the equivalent elastic strain is 0.001293mm, and the equivalent stress is 1.4163Map (see Figure 12 ).

[0110] (2) Separation state

[0111] The fine sand layer is divided into 4 fan-shaped breeding boxes. The pressure of the screen surface at the bottom of each fan-shaped breeding box is 3184.9Pa. The fan-shaped surface and the side surface are set as fixed supports. According to the simulation results, the maximum total deformation of the screen plate at the bottom of the fan-shaped breeding box after the force is applied is 0.82934mm, the equivalent elastic strain is 0.0016033mm, and the equivalent stress is 1.7563Map (see Figure 13 ).

[0112] 2.3 Static stress simulation of fine sand layer screen plate

[0113] The pressure of the fine sand layer is 12743.6075Pa. Since the fine sand layer is divided into 4 fan-shaped breeding boxes, when setting the pressure, the pressure is applied to the bottom screen plate of the breeding box respectively, and the pressure is applied to the sieve plate surface of the 4 breeding boxes. After the fine sand layer, prismatic support column, and fan-shaped breeding box 3D models are matched using SolidWorks.2018, they are substituted into ANSYSWorkbench 2021R1 as a simulation model. The outer wall relationship of the fine sand layer is set as a cylindrical support, and the support plate at the bottom of the sieve plate is set as a fixed support. According to the simulation results, the maximum total deformation of the bottom sieve plate of the cobblestone layer after being subjected to force is 0.034267mm, the equivalent elastic strain is 0.0002484mm, and the equivalent stress is 0.27165Map (see Figure 14 ).

[0114] 2.4 Static stress simulation of coarse sand layer screen plate

[0115] The pressure of the coarse sand layer is 5142.8538Pa. The bottom relationship of the prismatic column is set as a fixed support, and the bottom support plate of the screen plate is set as a fixed support. According to the simulation results, the maximum total deformation of the screen plate at the bottom of the cobblestone layer after the force is applied is 0.62258mm, the equivalent elastic strain is 0.0016601mm, and the equivalent stress is 1.7942Map (see Figure 15 ).

[0116] 2.5 Static stress simulation of the sieve plate in the pebble layer

[0117] The pressure of the pebble layer is 7820.5495Pa. The bottom relationship of the prismatic column is set as a fixed support, and the bottom support plate of the sieve plate is set as a fixed support. According to the simulation results, the maximum total deformation of the sieve plate at the bottom of the pebble layer after the force is applied is 0.9906mm, the equivalent elastic strain is 0.0042633mm, and the equivalent stress is 3.9953Map (see Figure 16 ).

[0118] 2.6 Internal structure stress simulation after assembly

[0119] The pressure of the bottom outlet space is the sum of the weight of the fan-shaped breeding box, fine sand layer, coarse sand layer, and pebbles. During the simulation process, the pressure of each layer is set to each surface. The pressure distribution is as follows: Figure 17As shown, the bottom surface of the bottom outlet space is set as a fixed support. Simulation results show that the maximum total deformation of the internal structure after loading is 0.60396mm, the equivalent elastic strain is 0.0030439mm, and the equivalent stress is 3.1455mA. Analysis of the stress conditions of each unit in the sand filter's internal structure using the ANSYS Workbench 2021R1 static structural analysis module shows that deformation is less than 1mm, meeting engineering requirements.

[0120] Example 5: Purification of water by Echinops unicinctus

[0121] Through the sand filter material test and the internal structure stress simulation of the sand filter in Example 4, the sand filter parameters are designed as follows:

[0122] 1. Water distribution device: The water distribution device is disc-shaped, connected to the water inlet pipe, with a height of 5 cm, a diameter of 20 cm, and a thickness of 3 cm. A circular array of water outlet holes is set at the bottom, with a hole diameter of 30 mm.

[0123] 2. Pool body protective cover: The center of the protective cover is connected to the surface of the water inlet pipe body. The overall shape is arc-shaped, with an inclination angle of 15°, a height of 30cm and a thickness of 3cm. Four symmetrical ventilation holes (diameter 15cm, thickness 3cm) are set on the protective cover.

[0124] 3. Inner layer sand and gravel structure: divided into upper (fine sand), middle (coarse sand), lower (pebbles), and bottom layer, with a wall thickness of 3cm and a diameter of 1.5m.

[0125] (1) Fine sand layer: divided into 4 sea intestine culture boxes with a height of 60 cm, fine sand filling 50 cm, and a 10 cm high overlying water space reserved on the upper layer; the fine sand layer filter material uses sea sand with a particle size of 0.8-1.2 mm, mainly filled with mud and sand, and a 100 mesh screen is set at the bottom.

[0126] (2) Coarse sand layer: 30 cm high, coarse sand particle size is 2-4 mm, and an 80-mesh screen is set at the bottom.

[0127] (3) Pebble layer: 30 cm high, pebble particle sizes of 25-30 mm and 45-50 mm, 15 cm thick respectively, with a 60-mesh sieve at the bottom.

[0128] (4) Prismatic support column: The upper part is a prism (60 cm high, 4 cm side length), and the lower part is a cylinder (60 cm high, ), passing through the fine sand, coarse sand and pebble layers, and setting a disc-shaped card plate (15 cm in diameter, 3 cm thick) at the bottom of the fine sand layer and the pebble layer respectively.

[0129] (5) Bottom water outlet space: The interior is a hollow structure with a "U"-shaped bottom profile, a slope of 15°, and a height of 30 cm. A hole-shaped drainage pipe is designed at the center of the bottom, extending to a prismatic cylindrical disc-shaped card plate. The height is 30 cm, the pipe diameter is 50 mm, and the hole diameter is 10 mm. With the center of the bottom circle as the center point, 6 cylindrical support columns are arranged in a circular array. The fine, coarse, and pebble layers extend from the bottom screen of the pebble layer to the bottom of the water outlet space. The column diameter is 15 mm and the height is about 20 mm. The actual parameters are based on the distance from the bottom to the pebble screen.

[0130] 3. Middle overflow space: 1.6m high, 1.2m in diameter, 2cm thick. Six cylindrical support columns (20cm high, 15mm in diameter) are arranged in a circular array, centered at the bottom center of the overflow space. A water outlet (50mm in diameter) is located at the center of the bottom, extending 20cm past the outer protective layer. This outlet allows for connection to the water pipe that will lead to the next water treatment unit in the RAS.

[0131] 4. Outer protective layer: 1.8m high, 1.2m in diameter, 2cm thick. Six support columns (20cm high, 15mm in diameter) are installed at the bottom, and a water outlet (50mm in diameter) is located at the center of the bottom.

[0132] 6. Pool body base: Weld 4 iron triangular prisms (40cm high, 10cm wide, 3cm thick) to the bottom of the outer protective layer to support the entire device.

[0133] 7. Wastewater collection tank: It is located on one side of the sand filter (60 cm long, 30 cm wide, 40 cm high, and 2 cm thick), and is equipped with an inlet and an outlet. The inlet is connected to the overflow pipe, and the outlet is connected to the inlet of the next sand filter.

[0134] 8. Pipeline laying: There are 4 pipes in the sand filter tank.

[0135] (1) Water inlet pipe: diameter 10 cm, wall thickness 2 cm, height 20 cm.

[0136] (2) Drain pipe: The upper 20 cm is a perforated drain pipe, and the lower 50 cm is a hollow drain pipe.

[0137] (3) Overflow layer outlet pipe: runs from the bottom of the overflow layer through the upper part of the outer protective layer to connect to the water inlet of the sewage collection tank.

[0138] (4) Sewage collection tank outlet pipe: It is located at the outlet of the sewage collection tank and is connected to the next sand filter tank in series and to the circulating water aquaculture inlet in parallel.

[0139] The adult larvae of the single-ringed spiny moth are cultured in fan-shaped sea intestine culture boxes, with a culture quantity of 200 adults / m 2This method simulates the purification effect of Spinella monocyclica on aquaculture tail water in a sand filter tank based on the purification and repair characteristics of Spinella monocyclica and the treatment effect of Spinella monocyclica on aquaculture tail water.

[0140] The physical and chemical indicators of water quality measured in the experiment include dissolved oxygen, total dissolved solids (TDS), ammonia nitrogen, nitrite, suspended solids, chemical oxygen demand (COD), etc. The results of the experiment on the effect of aquaculture tail water treatment by Echinops monocyclicus are shown in Table 7 and Figure 18 .

[0141] Table 7 Removal rate of various water quality indicators of aquaculture tail water by Echinops unicinctus

[0142]

[0143] According to the water purification test of sand filter media in Example 3, the treatment results of 0.8-1.2 mm sea sand on various indicators of aquaculture tail water are shown in Table 8, among which the removal rate of dissolved solids (TDS) and conductivity (CT) is good, and the dissolved oxygen content in the water body increases after filtration by sea sand.

[0144] Table 8 Removal rate of various water quality indicators of aquaculture tail water by 0.8-1.2mm sea sand

[0145]

[0146]

[0147] Chemical oxygen demand (COD) reflects the total amount of reducing substances in water that can consume dissolved oxygen. Generally, COD is inversely proportional to the dissolved oxygen content. When dissolved oxygen levels increase, COD decreases. Sand filtration increases dissolved oxygen, which in turn reduces COD. Furthermore, sand filtration also reduces the dissolved solids content in the water. The removal rate of COD in aquaculture tailwater by E. monocylindrica was 12.46%, and its removal rate of suspended solids was as high as 77.18%. The reduction in COD indicates improved water quality, while the reduction in suspended solids and total solids also demonstrates the filtration effectiveness of the sand filter and E. monocylindrica. Overall, combining E. monocylindrica with sand filters can further enhance the purification of aquaculture tailwater, achieving higher treatment standards and providing an effective method for environmental protection and improving aquaculture water quality.

[0148] The present invention and its embodiments are described above. This description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure and material are not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without creatively designing them, they shall fall within the scope of protection of the present invention.

Claims

1. A device for treating tail water from factory farming using acanthocephala monocyclica, wherein the bottom of the device is supported by legs (17), a water inlet pipe (1) is provided on the top, and a sand filter body (18) is provided inside, characterized in that: The outer side of the sand filter body (18) is provided with a hollow overflow layer (11) and an outer protective layer (13) in sequence, a tank body protective cover (2) is provided above the outer protective layer (13), and the tank body protective cover (2) is provided with a protective cover vent (2a); an overflow siphon (12) is provided at the bottom of the hollow overflow layer (11), and the highest point of the overflow siphon (12) is lower than the upper edge of the sand filter body (18); an alarm controller (16) is provided on the overflow siphon (12); and load-bearing pillars (14) are provided between adjacent layers of the sand filter body (18), the hollow overflow layer (11) and the outer protective layer (13); The sand filter body (18) is divided into three layers by the sea intestine culture box support screen plate (4), the coarse sand screen (6) and the pebble screen (8), namely the fine sand layer (3), the coarse sand layer (5) and the pebble layer (8); a water distributor (1a) is provided at the bottom of the water inlet pipe (1), and the water distributor (1a) is suspended above the fine sand layer (3); The lower side of the pebble screen (8) and the bottom of the sand filter body (18) form a water collection chamber (9), and a load-bearing pillar (14) is provided in the water collection chamber (9), and its two ends are respectively connected to the pebble screen (8) and the sand filter body (18); a prismatic fixed column (20) is provided at the center above the pebble screen (8), and the prismatic fixed column (2) sequentially passes through the coarse sand screen (6), the coarse sand layer (5) and the sea intestine culture tank support screen plate (4) and extends to the fine sand layer (3); the lower center of the pebble screen (8) is connected to one end of the porous drainage pipe (10), and the drainage pipe (10) sequentially passes through the sand filter body (18), the hollow overflow layer (11) and the outer protective layer (13) and is provided with a water outlet (15) at the other end, and a drainage hole (10a) is provided on the portion of the porous drainage pipe (10) placed in the water collection chamber (9); The fine sand layer (3) is provided with a plurality of fan-shaped sea intestine culture boxes (3a) with a prismatic fixed column (20) as the center. The fan-shaped sea intestine culture box (3a) is provided with a curved plate (3b), a prismatic flat plate (3d) and a screen partition (3c) to form a fan-shaped structure. A bottom screen plate (3f) is provided at the bottom of the fan-shaped sea intestine culture box (3a). A curved guard plate (3e) folded to the upper edge of the sand filter tank body (18) is provided on the curved plate (3b); and a lifting lug (3g) for lifting is provided on the curved guard plate (3e).

2. A method for treating factory aquaculture tail water using Echinops unicinctus, characterized by: The method uses the device described in claim 1 to cultivate Echinops unicinctus to treat factory aquaculture tail water; the method specifically comprises the following steps: a. Cultivate the juvenile or adult larvae of the single-ringed spiny moth in a fan-shaped sea intestine culture box (3a). The number of adult larvae cultured is 200-250 / m 2 The number of juveniles cultured is 3500~4500 / m 2 The fine sand filter material occupies 5 / 6 of the height of the fan-shaped sea intestine culture box (3a), and the upper layer reserves the overlying water space; the fine sand layer filter material uses sea sand with a particle size of 0.8-1.2mm; b. The aquaculture tail water passes through the water inlet pipe (1) and the water distributor (1a) into the fine sand layer (3) of the sand filter body (18). At this time, the monocyclic spiny worms in the fan-shaped sea intestine aquaculture box (3a) absorb the nutrients in the aquaculture tail water; at the same time, the fine sand layer (3) filters the aquaculture tail water; c. The aquaculture tail water after passing through the fine sand layer (3) passes through the bottom sieve plate (3f) and the sea intestine aquaculture box support sieve plate (4) in sequence, and enters the coarse sand layer (5) for filtration; the aquaculture tail water after passing through the coarse sand layer (5) passes through the coarse sand screen (6) and enters the pebble layer (7), and then passes through the pebble screen (8) and enters the water collection chamber (9); d. The water in the water collecting chamber (9) enters the porous drainage pipe (10) through the drainage hole (1a) and is discharged from the water outlet (15); e. When the hydraulic load of the sand filter (18) is overloaded, the aquaculture tail water will overflow into the hollow overflow space, and the bottom of the hollow overflow layer (11) will flow to the next sand filter or sewage collection tank (19) through the overflow siphon (12); f. An overflow siphon (12) with an alarm controller (16) is provided on the sand filter tank of the last stage. The alarm controller (16) can control the start and stop of water inlet of the water inlet pipe (1). When the alarm controller (16) detects water flow, the water inlet of the water inlet pipe (1) is stopped; when the alarm controller (16) detects no water flow, the water inlet of the water inlet pipe (1) is started; g. When the outlet of the overflow siphon (12) is connected to the sewage collecting tank (19), the aquaculture tail water is blocked by the sewage collecting tank partition (19a) when it is discharged into the sewage collecting tank (19), so that the impurities in the aquaculture tail water before the sewage collecting tank partition (19a) are settled; the aquaculture tail water after the sewage collecting tank partition (19a) is discharged from the drainage outlet of the sewage collecting tank after settling.

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