A closed-loop water purification system for Hirudo medicinalis farming

Abstract

This invention relates to the field of aquaculture water purification technology, specifically a closed-loop water purification system for Hirudo medicinalis aquaculture. The system includes a filter cake assembly and a purification assembly arranged sequentially below the overflow point of the aquaculture tank. The filter cake assembly includes a guide cylinder and several circulating sludge removal sections arranged in a ring around the outside of the guide cylinder. The guide cylinder is composed of a diversion column, a diversion sleeve, and an outer cylinder, arranged sequentially from the inside out with gaps. The outer wall of the diversion column has several layers of axially distributed diversion blocks, and the side wall of the diversion sleeve has several diversion ports corresponding to the positions of several pairs of diversion blocks. The outer wall of the outer cylinder has several filter strips embedded in a ring at equal intervals. This invention, by setting up a guide cylinder composed of a diversion column, a diversion sleeve, and an outer cylinder, and cooperating with staggered diversion blocks and diversion ports, achieves multi-stage deceleration, dispersion, and guidance of overflow water with high solid content, thereby greatly reducing the impact force of the water flow and ensuring uniform water distribution.

Description

Technical Field

[0001] This invention relates to the field of aquaculture water purification technology, specifically a closed-loop water purification system for Hirudo medicinalis aquaculture. Background Technology

[0002] During the farming of leeches, a large amount of feces and uneaten feed residue are produced.

[0003] Patent application CN202221204166.1 discloses a *Hirudo medicinalis* (horn goat leech) breeding pond with water quality improvement function. It includes an indoor breeding pond, a first fixed platform, and a second fixed platform, as well as an outdoor circulating pond. A first water pump is mounted on the top of the first fixed platform. The input end of the first water pump is connected to a first pumping pipe, with the end of the pump away from the pump located in the indoor breeding pond. The output end of the pump is connected to a first delivery pipe, with the end of the delivery pipe away from the pump located in the outdoor circulating pond. Breeding *Hirudo medicinalis* in the indoor breeding pond avoids the impact of adverse environmental factors on its growth. *Hylocereus undatus* is cultivated in the outdoor circulating pond, and EM bacteria and nitrifying bacteria are regularly added for water purification. The first and second water pumps transport the water from the outdoor circulating pond (with improved water quality) to the indoor breeding pond, keeping the water in the breeding pond in a circulating state.

[0004] This scheme primarily involves pumping water from indoor aquaculture ponds to outdoor circulating ponds, where algae are cultivated and EM bacteria and nitrifying bacteria are introduced for biological purification. The water is then returned to the indoor ponds. However, this type of system has significant drawbacks: First, its purification relies heavily on biological processes, which are slow to take effect and struggle to handle the large amounts of solid particles generated during aquaculture, easily leading to system overload. Second, it fails to effectively address the physical separation and immediate removal of solid waste; pollutants merely circulate and accumulate within the system, ultimately requiring large-scale water replacement, resulting in low water resource utilization and the risk of biological purification system failure.

[0005] Therefore, existing technologies lack a dedicated system that can be integrated into the aquaculture environment to perform instant and efficient physical filtration of wastewater rich in solid particles and achieve compact closed-loop purification of water. Summary of the Invention

[0006] In order to overcome the defects in the prior art, the purpose of this invention is to provide a closed-loop water purification system for leech farming. Through a multi-stage deceleration and dispersion impact filter assembly, particulate impurities such as feces and food residue in the water are efficiently removed, reducing the load on subsequent purification units, thereby achieving efficient purification and recycling of the farming water to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides a closed-loop water purification system for raising Hirudo medicinalis, including a breeding tank for raising Hirudo medicinalis, and a filter cake group and a purification group are arranged sequentially below the overflow point of the breeding tank.

[0008] The filter residue assembly is used for preliminary filtration of wastewater containing particulate impurities overflowing from the breeding tank; the purification assembly is used to collect the water after preliminary filtration, perform sedimentation and purification, and return the purified water to the breeding tank.

[0009] The filter cake assembly includes a flow guide cylinder and several circulating slag removal sections arranged in a ring around the outside of the flow guide cylinder; the flow guide cylinder is composed of a flow divider column, a flow divider sleeve, and an outer cylinder arranged sequentially from the inside to the outside with gaps; the inside of the flow guide cylinder forms two annular water passage gaps for diverting water overflowing from the aquaculture tank;

[0010] The outer wall of the diversion column is provided with several layers of diversion blocks distributed along the axial direction, and the diversion blocks in each layer are staggered in the circumferential direction; the side wall of the diversion sleeve is provided with several diversion ports corresponding to the positions of several pairs of diversion blocks; the outer wall of the outer cylinder is provided with several filter belts in an annular shape at equal intervals, the filter belts are square closed loops and are circulated and conveyed by a pair of drive rollers, and a pair of scrapers are provided on the outer vertical side of the filter belts.

[0011] When the water flows from top to bottom through the two annular water gaps inside the guide tube, the water in the inner water gap is dispersed and its flow direction is changed multiple times through the staggered diversion blocks of each layer. It is thrown out from several diversion ports and comes into contact with the outer water gap to slow down the water flow. It also hits several filter belts on the inner wall of the outer cylinder and is filtered and transported out. After being scraped clean by the scraper, the filter residue is reabsorbed.

[0012] As a further improvement to this technical solution, the outer wall of the outer cylinder is provided with several openings at equal intervals in a ring shape. A pivot pin is inserted between the upper and lower side walls of each opening. The filter belt passes around two pivot pins to seal the openings, which is used to receive the water flow thrown out from several diversion ports and filter it.

[0013] As a further improvement to this technical solution, support rollers are fitted at the upper and lower corners of the outer vertical section of the filter belt. Both ends of the support rollers are fixedly connected to shaft frames. The shaft frames are double-hole frames and are distributed on the inner and outer sides of the filter belt. One of the scrapers is a serrated plate, and a guide plate is provided at the lower end of the serrated plate to guide the filter residue to slide to the ground.

[0014] As a further improvement to this technical solution, the purification group includes a sedimentation tank and a recovery tank arranged inside and outside each other. The sedimentation tank is used to receive water filtered by the filter cake group and to purify suspended solids through sedimentation.

[0015] As a further improvement to this technical solution, the sedimentation tank is a cylindrical structure with a water receiving platform attached to its top port. The water receiving platform is a truncated cone shell with several water inlets on its lower edge sidewall. The top sidewall of the sedimentation tank is annularly provided with several overflow outlets, and the overflow outlets are positioned lower than the water inlets.

[0016] As a further improvement to this technical solution, a filter cloth is provided on the top of the water receiving platform for further filtration of the filtered water.

[0017] As a further improvement to this technical solution, the recycling bin is an annular box with several return ports on its top sidewall. The positions of the return ports and the overflow ports correspond one-to-one, forming a water circulation loop. A pump is installed on the top of the recycling bin.

[0018] As a further improvement to this technical solution, a water filter platform is provided at the center of the bottom surface of the breeding box, and the top of the diversion column is fastened to the water filter platform by a clip; a supply pipe is provided on the top edge of the breeding box for replenishing new water into the breeding box or receiving purified water returning from the recycling box.

[0019] As a further improvement to this technical solution, the bottom of the diversion column is provided with a connecting platform, which is fixedly connected to the bottom of the diversion sleeve, and a seal is fixedly provided on the side wall with the opening and between the turning pins.

[0020] As a further improvement to this technical solution, the bottom surface of the breeding box is provided with a hanger, and the hanger and the support roller are fixedly connected by pins.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. This closed-loop water purification system for Hirudo medicinalis aquaculture, through the setting of a guide tube consisting of a diversion column, a diversion sleeve, and an outer cylinder, and in conjunction with staggered diversion blocks and diversion ports, completes multi-stage deceleration, dispersion, and guidance of overflow water with high solid content. This achieves the effect of greatly reducing the impact force of water flow and making the water flow evenly distributed, creating a key prerequisite for the stable and efficient filtration of the subsequent filter belt, and fundamentally solving the problem of filter belt blockage or uneven filtration caused by high-speed water flow impact.

[0023] 2. This closed-loop water purification system for Hirudo medicinalis aquaculture uses a closed-loop filter belt driven by a drive roller, arranged in a ring on the outer cylinder, along with a serrated scraper, to continuously intercept, transport, scrape, and collect filter residue. This achieves the immediate and automatic separation and removal of solid pollutants from the water, enabling online self-cleaning and recycling of the filter belt, effectively preventing filter belt clogging and the accumulation of pollutants within the system.

[0024] 3. This closed-loop water purification system for leech farming integrates the breeding tank, filter cake group, and purification group into a compact whole, forming a closed-loop water circuit. It completes the entire process from wastewater generation, immediate filtration, deep purification to water reuse, achieving a highly efficient internal circulation effect for the farming water and maximizing water resource conservation. Attached Figure Description

[0025] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. Those skilled in the art, guided by the teachings of this invention, will select various possible shapes and proportions to implement the invention according to specific circumstances.

[0026] Figure 1 This is a schematic diagram of the overall assembly structure of the present invention;

[0027] Figure 2 For the present invention Figure 1 The main view;

[0028] Figure 3 This is a schematic diagram of the assembly structure of the filter cake assembly and purification assembly of the present invention;

[0029] Figure 4 This is a schematic diagram of the guide tube assembly structure of the present invention;

[0030] Figure 5 This is a schematic diagram of the flow divider structure of the present invention;

[0031] Figure 6 This is a schematic diagram of the diversion sleeve structure of the present invention;

[0032] Figure 7 This is a schematic diagram of the assembly structure of the circulating slag removal section of the present invention;

[0033] Figure 8 This is an exploded view of the drive roller assembly of the present invention;

[0034] Figure 9 This is a disassembled view of the scraper assembly of the present invention;

[0035] Figure 10 This is a schematic diagram of the purification unit assembly structure of the present invention;

[0036] Figure 11 This is a schematic diagram of the sedimentation tank structure of the present invention;

[0037] Figure 12 This is a schematic diagram of the recycling bin structure of the present invention;

[0038] The meanings of the labels in the diagram are as follows:

[0039] 100. Breeding box; 110. Water filter platform; 120. Supply pipe;

[0040] 200. Filter cake assembly; 210. Flow guide cylinder; 211. Flow divider column; 2111. Flow divider block; 2112. Connecting platform; 2113. Locking strip; 212. Flow divider sleeve; 2121. Flow divider port; 213. Outer cylinder; 2131. With opening; 2132. Turning pin; 2133. Seal strip;

[0041] 220. Circulating slag removal section; 221. Filter belt; 222. Belt support roller; 2221. Shaft bracket; 223. Drive roller; 224. Scraper; 225. Hanger;

[0042] 300. Purification unit; 310. Sedimentation tank; 311. Water receiving platform; 312. Water inlet; 313. Overflow outlet; 320. Recovery tank; 321. Return outlet; 330. Filter cloth. Detailed Implementation

[0043] The details of the present invention can be more clearly understood by referring to the accompanying drawings and the description of specific embodiments. However, the specific embodiments of the present invention described herein are for illustrative purposes only and should not be construed as limiting the invention in any way. Under the teachings of this invention, those skilled in the art will conceive of any possible variations of the invention, all of which should be considered within the scope of the invention. The terms "installation" and "connection" should be interpreted broadly, referring to direct connection as well as indirect connection through an intermediate medium.

[0044] The terms "central axis," "vertical," "horizontal," "front," "rear," "upper," "lower," "left," "right," "top," "bottom," "inner," and "outer" used herein to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of the invention, "a number" means two or more, unless otherwise explicitly specified.

[0045] Please see Figures 1-9As shown, this invention provides a closed-loop water purification system for Hirudo medicinalis farming, including a farming tank 100 for raising Hirudo medicinalis. Below the overflow point of the farming tank 100, a filter cake assembly 200 and a purification assembly 300 are sequentially arranged. A water filter platform 110 is located at the center of the bottom surface of the farming tank 100 to intercept water and maintain a humid environment inside the farming tank 100 for the survival of the Hirudo medicinalis. A supply pipe 120 is located on the top edge of the farming tank 100 to replenish fresh water into the farming tank 100. When the farming tank 100 overflows, the water flows into the filter cake assembly 200 through the inner hole of the water filter platform 110 for filtering, which is responsible for the preliminary physical filtration of wastewater rich in solid particles.

[0046] The filter residue group 200 is used to perform preliminary filtration of wastewater containing particulate impurities that overflows from the breeding tank 100; the purification group 300 is used to collect the water after preliminary filtration, perform sedimentation and purification, and return the purified water to the breeding tank 100.

[0047] The filter cake assembly 200 includes a guide cylinder 210 and several circulating slag removal sections 220 arranged in a ring around the outside of the guide cylinder 210. The guide cylinder 210 is composed of a diverter column 211, a diverter sleeve 212, and an outer cylinder 213 arranged sequentially from the inside to the outside with gaps. The bottom of the diverter column 211 is provided with a connecting platform 2112, which is fixedly connected to the bottom of the diverter sleeve 212, such as by threaded connection or tight sleeve. The top of the diverter column 211 is clamped to the water filter platform 110 by a retaining strip 2113, which is embedded in the top of the diverter column 211 to suspend the filter cake assembly 200 in the inner hole of the water filter platform 110. The inside of the guide cylinder 210 forms two annular water passage gaps to divert water overflowing from the aquaculture tank 100.

[0048] The outer wall of the diversion column 211 is provided with several layers of diversion blocks 2111 distributed along the axial direction, and the several diversion blocks 2111 in each layer are staggered in the circumferential direction; the side wall of the diversion sleeve 212 is provided with several diversion ports 2121 corresponding to the positions of several pairs of diversion blocks 2111; the outer wall of the outer cylinder 213 is provided with several filter belts 221 embedded in a ring at equal intervals, the filter belts 221 are square closed loops and are clamped and circulated by a pair of drive rollers 223, and a pair of scrapers 224 are provided on the outer vertical side of the filter belts 221.

[0049] When the water flows from top to bottom through the two annular water gaps inside the guide tube 210, the water in the inner water gap is dispersed and its flow direction is changed multiple times through the staggered diversion blocks 2111. It is thrown out from several diversion ports 2121 and comes into contact with the outer water gap to slow down the water flow. It also hits several filter belts 221 on the inner wall of the outer tube 213 and is filtered and transported out. After being scraped off by the scraper 224, the filter residue is reabsorbed.

[0050] After entering the guide tube 210, the aquaculture wastewater flows into the gap between the diversion column 211 and the diversion sleeve 212, and the gap between the outer cylinder 213 and the diversion sleeve 212. As the water flows downwards, it continuously impacts the staggered diversion blocks 2111 at each layer. This design produces multiple beneficial effects:

[0051] Gradual deceleration: Each layer of diversion block 2111 creates resistance to the water flow, causing its flow velocity to gradually decrease.

[0052] Changing the flow direction and dispersing the water flow: The staggered arrangement of the diversion blocks 2111 forces the water flow to constantly change direction and discharge it from the gaps between the diversion blocks 2111, thus dispersing the concentrated water flow into multiple small water flows.

[0053] Uniform impact: After being dispersed and slowed down through multiple stages, the water flow is finally thrown out smoothly and evenly from several diversion ports 2121, and is further slowed down by colliding with the water flow in the gap between the outer cylinder 213 and the diversion sleeve 212, before hitting the inner wall of the outer cylinder 213. This process greatly reduces the direct impact force of the water flow on the subsequent filter media, creating conditions for high-efficiency filtration.

[0054] The filter belt 221 is a mesh belt woven from polyester PET monofilament fibers. Its filtration accuracy is between 100 mesh and 200 mesh. The advantages of using a monofilament filter mesh are: its smooth and flat surface allows the trapped filter residue to be easily and thoroughly scraped off by the scraper 224, effectively preventing clogging of the filter belt holes and ensuring the durability of filtration efficiency; at the same time, this material has excellent tensile strength and wear resistance, and can withstand the continuous compression of the drive roller 223 and mechanical fatigue during cyclic operation, extending its service life, making it particularly suitable for applications like this system that require continuous operation and mechanical self-cleaning.

[0055] Furthermore, the outer wall of the outer cylinder 213 has several annularly spaced openings 2131. A pivot pin 2132 is inserted between the upper and lower sidewalls of each opening 2131. The filter belt 221 passes over two pivot pins 2132 to seal the openings 2131, thus receiving and filtering the water flow ejected from the several branch outlets 2121. A sealing strip 2133 is fixedly installed on the sidewall of the openings 2131 between the pivot pins 2132 to resist the impact of water flow on the side of the filter belt 221 and prevent leakage.

[0056] Furthermore, support rollers 222 are fitted at the upper and lower corners of the outer vertical section of the filter belt 221, which, together with two pivot pins 2132, support the filter belt 221 into a square closed shape for repeated use; a hanger 225 is provided on the bottom surface of the breeding box 100, and the hanger 225 is fixedly connected to the support rollers 222 by pins; both ends of the support rollers 222 are fixedly connected to shaft frames 2221, which are double-hole frames distributed on the inner and outer sides of the filter belt 221, one of which is a serrated plate with a guide plate at the lower end of the serrated plate to guide the filter residue to slide to the ground and prevent the filter residue from falling into the purification unit 300.

[0057] like Figures 10-12 As shown, the purification unit 300 includes an inner and outer sedimentation tank 310 and a recovery tank 320. The sedimentation tank 310 is used to receive water filtered by the filter cake assembly 200 and purify suspended solids through sedimentation. The sedimentation tank 310 has a cylindrical structure and a water receiving platform 311 is attached to its top port. The water receiving platform 311 has a truncated cone shell and several water inlets 312 are opened on its lower edge side wall. A filter cloth 330 is installed on the top of the water receiving platform 311 for further filtration of the filtered water. Several overflow ports 313 are opened in a ring on the top side wall of the sedimentation tank 310. The overflow ports 313 are lower than the water inlets 312, so that the supernatant in the sedimentation tank 310 is discharged only from the overflow ports 313 and will not flow back to the water receiving platform 311.

[0058] Furthermore, the recycling tank 320 is an annular box with several return ports 321 annularly opened on its top sidewall. The positions of the return ports 321 and the overflow ports 313 correspond one-to-one, forming a water circulation loop, so that the supernatant inside the sedimentation tank 310 flows to the recycling tank 320. A pump is installed on the top of the recycling tank 320 to draw the purified water inside the recycling tank 320. A supply pipe 120 is provided on the top edge of the breeding tank 100 to replenish the breeding tank 100 with the purified water returning from the recycling tank 320.

[0059] In operation, the closed-loop water purification system for Hirudo medicinalis aquaculture of this invention maintains a dynamic overflow state in the breeding tank 100 due to continuous replenishment or the activity of the Hirudo medicinalis. The overflow water containing feces and feed residue flows evenly into the filter cake assembly 200 below through the inner hole of the filter platform 110. The water flow first enters the interior of the guide cylinder 210 and is divided by two annular water passage gaps between the diversion column 211 and the diversion sleeve 212, and between the diversion sleeve 212 and the outer cylinder 213.

[0060] As the water flows downward through the gaps in the inner channel, it continuously impacts several staggered diversion blocks 2111 arranged in multiple layers on the outer wall of the diversion column 211. Each time the water passes through a layer of diversion blocks 2111, its direction is forcibly changed and it disperses into smaller tributaries, achieving gradual deceleration. Finally, this fully dispersed water, with its kinetic energy significantly reduced, is gently ejected from the corresponding diversion ports 2121 on the diversion sleeve 212, where it collides with the water flowing through the gaps in the outer channel, further slowing its velocity before evenly impacting multiple filter belts 221 on the inner wall of the outer cylinder 213.

[0061] Meanwhile, the drive roller 223 continues to operate, driving the closed-loop filter belt 221 to circulate around the pivot pin 2132 and the support roller 222. Water flows through the filter belt 221, and solid particles are trapped on the surface of the filter belt 221. As the filter belt 221 circulates, when the belt surface carrying filter cake moves to the outer vertical position, it comes into contact with the fixed scraper 224. The serrated scraper 224 completely scrapes the filter cake off the filter belt 221, and the scraped filter cake slides down the guide plate into the ground collection container, realizing the immediate separation and removal of solid pollutants. The water filtered by the filter belt 221 drips downwards and enters the purification unit 300. The water entering the purification unit 300 first falls onto the water receiving platform 311 and undergoes secondary fine filtration through the filter cloth 330 laid on it, further removing fine suspended solids. Subsequently, the water flows into the sedimentation tank 310 through the water inlet 312 at the lower edge of the water receiving platform 311. In the sedimentation tank 310, the water flow rate slows down, and the remaining tiny particles gradually settle to the bottom of the tank under the action of gravity. The supernatant water level continues to rise, and when it reaches the height of the overflow port 313 on the side wall of the sedimentation tank 310, the clear supernatant overflows and flows into the corresponding recovery tank 320, which surrounds the sedimentation tank 310 in a ring shape.

[0062] The collection tank 320 collects the purified water, which is then pumped through pipes by a pump mounted on its top to the supply pipe 120 on the top of the breeding tank 100, and finally flows back into the breeding tank 100, completing the entire closed-loop water circulation process of "overflow-filtration-purification-return". The system operates in this cyclical manner, achieving continuous, efficient, and automated purification of the breeding water, significantly reducing the frequency of water changes, and providing a stable and clean living environment for the leeches.

[0063] It should be noted that the fixed connections and fixing methods of the present invention are achieved using conventional fixing means such as bolt connections or welding. The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A closed-loop water purification system for Hirudo medicinalis farming, comprising a farming tank for raising Hirudo medicinalis, characterized in that: Below the overflow point of the breeding box, there are filter residue group and purification group in sequence; The filter residue assembly is used for preliminary filtration of wastewater containing particulate impurities overflowing from the breeding tank; the purification assembly is used to collect the water after preliminary filtration, perform sedimentation and purification, and return the purified water to the breeding tank. The filter cake assembly includes a flow guide cylinder and several circulating slag removal sections arranged in a ring around the outside of the flow guide cylinder; the flow guide cylinder is composed of a flow divider column, a flow divider sleeve, and an outer cylinder arranged sequentially from the inside to the outside with gaps; the inside of the flow guide cylinder forms two annular water passage gaps for diverting water overflowing from the aquaculture tank; The outer wall of the diversion column is provided with several layers of diversion blocks distributed along the axial direction, and the diversion blocks in each layer are staggered in the circumferential direction; the side wall of the diversion sleeve is provided with several diversion ports corresponding to the positions of several pairs of diversion blocks; the outer wall of the outer cylinder is provided with several filter belts in an annular shape at equal intervals, the filter belts are square closed loops and are circulated and conveyed by a pair of drive rollers, and a pair of scrapers are provided on the outer vertical side of the filter belts. When the water flows from top to bottom through the two annular water gaps inside the guide tube, the water in the inner water gap is dispersed and its flow direction is changed multiple times through the staggered diversion blocks of each layer. It is thrown out from several diversion ports and slows down the water flow when it comes into contact with the outer water gap. The water flow hits several filter belts on the inner wall of the outer cylinder and is intercepted by filter residue. The filter residue is then transported out with the filter belts in a circulation. After the filter belts are scraped clean by the scraper, they reabsorb the filter residue.

2. The closed-loop water purification system for Hirudo medicinalis aquaculture according to claim 1, characterized in that: The outer wall of the outer cylinder has several openings at equal intervals in a ring shape. A pivot pin is inserted between the upper and lower side walls of each opening. The filter belt passes around two pivot pins to seal the openings, which is used to receive the water flow thrown out from several branch outlets and filter it.

3. The closed-loop water purification system for Hirudo medicinalis aquaculture according to claim 2, characterized in that: Support rollers are fitted at the upper and lower corners of the outer vertical section of the filter belt. The two ends of the support rollers are fixedly connected to the shaft frame. The shaft frame is a double-hole frame and is distributed on the inner and outer sides of the filter belt. One of the scrapers is a serrated plate, and a guide plate is provided at the lower end of the serrated plate to guide the filter residue to slide to the ground.

4. The closed-loop water purification system for Hirudo medicinalis aquaculture according to claim 3, characterized in that: The purification unit includes an inner and outer sedimentation tank and a recovery tank. The sedimentation tank is used to receive water filtered by the filter cake unit and to purify suspended solids through sedimentation.

5. The closed-loop water purification system for Hirudo medicinalis farming according to claim 4, characterized in that: The sedimentation tank has a cylindrical structure and a water receiving platform is attached to its top port. The water receiving platform is a truncated cone shell with several water inlets on its lower edge sidewall. The top sidewall of the sedimentation tank has several overflow outlets in a ring shape, and the overflow outlets are located lower than the water inlets.

6. The closed-loop water purification system for Hirudo medicinalis aquaculture according to claim 5, characterized in that: The water receiving platform is equipped with a filter cloth for further filtration of the filtered water.

7. The closed-loop water purification system for Hirudo medicinalis aquaculture according to claim 6, characterized in that: The recycling bin is a ring-shaped box with several return ports on its top sidewall. The positions of the return ports and the overflow ports correspond one-to-one, forming a water circulation loop. A pump is installed on the top of the recycling bin.

8. The closed-loop water purification system for Hirudo medicinalis aquaculture according to claim 7, characterized in that: A water filter platform is provided at the center of the bottom surface of the breeding box, and the top of the diversion column is attached to the water filter platform by a clip; a supply pipe is provided on the top edge of the breeding box for replenishing new water into the breeding box or receiving purified water returning from the recycling box.

9. The closed-loop water purification system for Hirudo medicinalis aquaculture according to claim 8, characterized in that: The bottom of the diversion column is provided with a connecting platform, which is fixedly connected to the bottom of the diversion sleeve. The side wall with the opening and located between the turning pins is fixedly provided with a seal.

10. The closed-loop water purification system for Hirudo medicinalis aquaculture according to claim 9, characterized in that: The bottom of the breeding box is equipped with a hanging frame, which is fixedly connected to the support roller by pins.

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