Novel freshwater fish factory recirculating aquaculture system

Abstract

The utility model provides a novel freshwater fish factory recirculating aquaculture system which comprises an aquaculture pond, a vertical flow precipitator, a microfilter pond, a biochemical air floatation pond, a sand cylinder filter, a nano denitrification system and a multi-stage air stripping system, the aquaculture pond is respectively connected with the vertical flow precipitator and the microfilter pond, the vertical flow precipitator is connected with the microfilter pond, the biochemical air floatation pond is connected with the sand cylinder filter, and the nano denitrification system is connected with the biochemical air floatation pond. The biochemical air floatation tank is connected with the microfilter tank through a pipeline, the biochemical air floatation tank comprises an air floatation bin, a pump bin, a biochemical bin and a denitrification bin, and the pump bin is respectively connected with the sand cylinder filter, the nano denitrification system and the multi-stage air stripping system through pipelines; and circulating pumps are arranged on pipelines for connecting the pump bin with the sand cylinder filter, the nano denitrification system and the multi-stage air stripping system. According to the utility model, the multi-stage cooperative treatment system is constructed and the denitrification system is introduced, so that the total nitrogen removal rate of the culture system is increased to 96%, which is increased by 140% compared with that of the traditional system, the water supplementing amount of the system is reduced, the daily water supplementing amount is reduced to be less than 3%, and the water-saving rate of the total circulating water amount is more than 70%.

Description

Technical Field

[0001] This utility model relates to the field of aquaculture equipment technology, specifically to a novel freshwater fish factory-style recirculating aquaculture system. Background Technology

[0002] Freshwater fish are a type of fish that live in freshwater. The main farmed species include grass carp, black carp, mandarin fish, and black cod. Freshwater fish are rich in nutrients. However, traditional freshwater fish farming suffers from problems such as water waste, pollutant accumulation, and frequent disease outbreaks. Therefore, they are usually raised in aquaculture ponds. In order to recycle water resources, the circulating water needs to be treated during the farming process for reuse.

[0003] Currently, recirculating aquaculture systems (RAS) are rapidly being adopted in the aquaculture industry due to their high efficiency, water conservation, environmental friendliness, and eco-friendliness. RAS is a new aquaculture model that utilizes a recirculating water treatment system to purify and circulate the aquaculture water. This allows excess feed, fish and shrimp excrement, and other organic matter to be promptly separated from the water, preventing them from decomposing into toxic substances such as ammonia nitrogen and nitrite. Furthermore, through appropriate equipment, dissolved oxygen, temperature, and other indicators in the water are specifically treated to stabilize water quality within a scientifically reasonable range. This not only achieves zero pollution and zero emissions but also increases the economic benefits for farmers by allowing for higher stocking densities.

[0004] Existing recirculating aquaculture systems (RAS) mostly adopt a "culture pond → mechanical filtration → biological filter → disinfection → reuse" model. While various RAS systems are being developed and applied both domestically and internationally, almost none truly achieve zero-discharge standards. This is due to several factors: First, the system design is immature, equipment stability is poor, and nitrogen oxide removal relies on a single biofilm, leading to excessive levels of ammonia nitrogen and nitrite nitrogen in the water, necessitating large-scale water exchanges and resulting in the direct discharge of large amounts of aquaculture wastewater. Second, there is a lack of mature specialized treatment units for nitrite, leading to the accumulation of nitrates produced by nitrification. Accumulated nitrates can poison fish, requiring large-scale water exchanges to resolve this issue. Third, the efficiency of staged treatment of suspended solids and dissolved pollutants is low. Existing treatment technologies cannot effectively remove all suspended solids and dissolved pollutants, especially in staged treatment. Incomplete initial treatment leads to poor results in subsequent stages. Increased suspended particles in the water can easily clog fish gill openings, irritate gill filaments and mucous membranes, potentially causing respiratory difficulties and, in severe cases, suffocation and death.

[0005] To reduce the environmental damage caused by aquaculture, minimize pollution of aquaculture waters by aquaculture wastewater, ensure the quality and safety of aquatic products, and improve aquaculture yield and efficiency, it is necessary to develop a new type of freshwater fish factory-style recirculating aquaculture system to help efficiently solve the pollution problem of aquaculture. Utility Model Content

[0006] The purpose of this invention is to provide a novel freshwater fish recirculating aquaculture system that can significantly reduce the ammonia nitrogen content in the aquaculture water, improve aquaculture efficiency, reduce wastewater discharge, and lower operating costs.

[0007] The technical solution adopted in this utility model is as follows:

[0008] A novel freshwater fish recirculating aquaculture system includes a culture pond, a vertical flow sedimentation tank, a microfiltration tank, a biochemical flotation tank, a sand filter, a nano-denitrification system, a multi-stage stripping system, and a balancing tank. The culture pond is connected to the vertical flow sedimentation tank and the microfiltration tank, respectively. The vertical flow sedimentation tank is connected to the microfiltration tank. The biochemical flotation tank is connected to the microfiltration tank via pipes. The biochemical flotation tank is connected to the sand filter, the nano-denitrification system, and the multi-stage stripping system via pipes. The multi-stage stripping system is connected to the balancing tank via pipes. The multi-stage stripping system includes a stripping tower, which consists of a cylindrical tower body and a top cover installed at the top of the tower body. The tower body has a stagnant space, and a stripping water inlet pipe is installed at its bottom. The stripping water inlet pipe is connected to a pump chamber through a pipeline. Water in the pump chamber is pumped into the tower body through a circulating pump. The stripping tower is equipped with a packing layer and a water distributor. The water distributor is located at the upper end of the tower body. The stripping water inlet pipe enters the tower body and extends upward to connect with the water distributor. The packing layer is located below the water distributor. An exhaust port is evenly opened along the circumference of the upper middle part of the stripping tower wall. A fan is installed in the upper part of the tower body. A stripping drain pipe is installed at the lower end of the tower body. The stripping drain pipe is connected to a balance tank through a pipeline. The balance tank is connected to an aquaculture pond through a pipeline.

[0009] Furthermore, the aquaculture ponds are provided in multiple ways, arranged in an array. The vertical flow sedimentation tanks are also provided in multiple ways, with the number of vertical flow sedimentation tanks matching the number of aquaculture ponds. Each vertical flow sedimentation tank is connected to one aquaculture pond via a pipe.

[0010] Furthermore, a central pipe is provided at the center of the bottom surface of the aquaculture pond, and a water outlet sleeve is connected to the axial position of the bottom surface of the aquaculture pond. The water outlet sleeve includes an upper water outlet pipe, a lower water outlet pipe, and a sleeve mounting platform. The sleeve mounting platform is installed at the center of the bottom surface of the aquaculture pond, and an upper water outlet and a lower water outlet are provided on the sleeve mounting platform. The upper water outlet pipe is connected to the lower end of the upper water outlet, and the lower water outlet pipe is connected to the lower end of the lower water outlet. The lower end of the central pipe is installed on the upper water outlet and connected to the upper water outlet pipe. The upper water outlet pipe is connected to the microfiltration tank. A protective cover is provided at the lower end of the central pipe. The lower end of the protective cover is fastened to the bottom surface of the aquaculture pond. Several sewage discharge holes are opened at the lower end of the protective cover. The lower water outlet is open upwards, and the lower water outlet pipe is connected to the vertical flow sedimentation tank.

[0011] Furthermore, the biochemical flotation tank is connected to the microfiltration tank via a pipeline. The biochemical flotation tank includes a flotation chamber and a pump chamber, which are integrated closed box structures. The flotation chamber and the pump chamber are separated by a siphon mechanism. The siphon mechanism includes a first siphon plate and a second siphon plate. The first siphon plate is vertically installed at the bottom of the biochemical flotation tank, and its height is three-quarters of the height of the biochemical flotation tank. The second siphon plate is vertically installed at the top, and its height is two-thirds of the height of the biochemical flotation tank. The first siphon plate and the second siphon plate are set at a certain distance, and the first siphon plate and the second siphon plate have a certain area of ​​overlap in the projection direction.

[0012] Furthermore, the bottom of the flotation chamber has an inclined surface, the lowest end of which is located at the installation position of the first siphon plate. An aeration pipe is installed on the inclined surface at the bottom of the flotation chamber. An inclined surface is also provided inside the pump chamber, and a sewage discharge pipe is provided at the bottom end of the inclined surface.

[0013] Furthermore, the water distributor consists of multiple perforated tubes.

[0014] Furthermore, the packing layer is composed of multi-faceted hollow sphere packing and a packing base. The hollow sphere packing is placed on the packing base. The surface of the hollow sphere packing has several regular or irregular planes, which are spliced ​​together to form an uneven texture. The interior of the multi-faceted hollow sphere packing is a hollow structure.

[0015] Furthermore, the stripping tower is connected to a pH adjustment mechanism, which includes an automatic acid and alkali addition device connected to the tower body and a pH sensor installed inside the tower body.

[0016] Furthermore, a constant temperature system is provided in the balance tank. The constant temperature system includes a temperature sensor, a heater, and a cooler. The temperature sensor is electrically connected to the heater and the cooler.

[0017] Compared with the prior art, the beneficial effects obtained by this utility model are as follows:

[0018] 1. By constructing a multi-level collaborative treatment system and introducing a denitrification system, the total nitrogen removal rate of the aquaculture system was increased to 96%, which is 140% higher than that of the traditional system. At the same time, the water replenishment of the system was reduced to less than 3% per day, and the total water saving rate of the circulating water exceeded 70%.

[0019] 2. By using nano-air flotation ionization technology, the denitrification time can be shortened to 1.5 hours; the volume of the biological treatment tank can be greatly reduced, the floor space occupied can be reduced by 15%, and the operating cost can be significantly reduced.

[0020] 3. This application further optimizes the water quality of the aquaculture water body, thereby further increasing the stocking density of various fish species. Attached Figure Description

[0021] Appendix Figure 1 This is a schematic diagram of the structure of the novel freshwater fish factory-scale recirculating aquaculture system described in this utility model;

[0022] Appendix Figure 2 This is a plan view of the novel freshwater fish factory-scale recirculating aquaculture system described in this utility model;

[0023] Appendix Figure 3 It is attached Figure 2 The diagram shows the structure of the central tube.

[0024] Appendix Figure 4 It is attached Figure 1 The diagram shows the structure of the outlet sleeve.

[0025] Appendix Figure 5 It is attached Figure 1 The diagram shows the structure of a biochemical flotation tank.

[0026] Appendix Figure 6 It is attached Figure 1 The diagram shows the structure of the nano-denitrification system.

[0027] Appendix Figure 7 This is a schematic diagram of the stripping tower structure;

[0028] Appendix Figure 8 It is a three-dimensional diagram of the blowdown tower;

[0029] Appendix Figure 9 It is attached Figure 7 The diagram shows the structure of the water distributor.

[0030] Appendix Figure 10 It is attached Figure 7 The diagram shows the structural features of the surface of the multifaceted hollow sphere. Detailed Implementation

[0031] To explain in detail the technical content, structural features, objectives and effects of this utility model, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0032] like Figures 1-2 As shown, a novel freshwater fish factory-scale recirculating aquaculture system includes a culture pond 1, a vertical flow sedimentation tank 2, a microfiltration tank 3, a biochemical flotation tank 4, a sand filter 5, a nano-denitrification system 6, and a multi-stage stripping system 7.

[0033] The aquaculture pond 1 is connected to a vertical flow sedimentation tank 2 and a microfiltration tank 3, respectively. The vertical flow sedimentation tank 2 is connected to the microfiltration tank 3. The aquaculture pond 1 is used for freshwater fish farming. Multiple aquaculture ponds 1 are arranged in an array. The bottom of the aquaculture pond 1 has a conical structure to facilitate the collection of impurities. A central pipe 11 is set at the center of the bottom of the aquaculture pond 1. The central pipe 11 is vertically arranged. Figure 3 As shown, the central pipe 11 has a tubular structure, with arrayed through holes 111 in both its middle and upper parts. The through holes 111 have a diameter of 5 mm and a spacing of 12 mm. The middle and upper layers of water in the aquaculture pond 1 enter the central pipe 11 through the through holes 111, and an outlet sleeve 13 is connected at the axial position of the bottom surface of the aquaculture pond 1. Figure 4 As shown, the water outlet sleeve 13 includes an upper water outlet pipe 12, a lower water outlet pipe 14, and a sleeve mounting platform 15. The sleeve mounting platform 15 is installed at the center of the bottom surface of the aquaculture tank 1. The sleeve mounting platform 15 is equipped with an upper water outlet 151 and a lower water outlet 152. The upper water outlet pipe 12 is connected to the lower end of the upper water outlet 151, and the lower water outlet pipe 14 is connected to the lower end of the lower water outlet 152. The lower end of the central pipe 11 is installed on the upper water outlet 151 and connected to the upper water outlet pipe 12. The middle and upper layers of water in the aquaculture tank 1 enter the upper water outlet pipe 12 through the central pipe 11. The upper water outlet pipe 12 is connected to the microfiltration tank 3, and the upper water is transported to the microfiltration unit through the upper water outlet pipe 12. The pool 3 is used for filtration; a protective cover 112 is provided at the lower end of the central pipe 11. The lower end of the protective cover 112 is fastened to the bottom surface of the aquaculture pool 1. The protective cover 112 is in the shape of a frustum. Several sewage discharge holes 113 are opened at the lower end of the protective cover 112. The bottom water in the aquaculture pool 1 enters the protective cover 112 through the sewage discharge holes 113. The lower water outlet 152 is set to open upward. The water entering the protective cover 112 enters the lower water outlet 152 and is discharged through the lower water outlet pipe 14. Since the bottom water in the aquaculture pool 1 contains a large amount of feed residue, fish feces and other impurities, most of the impurities in the aquaculture pool 1 can be discharged through the lower water outlet pipe 14. The lower water outlet pipe 14 is connected to the vertical flow sedimentation device 2.

[0034] Multiple vertical flow sedimentation tanks 2 are provided, with the number of vertical flow sedimentation tanks 2 matching the number of aquaculture ponds 1. Each vertical flow sedimentation tank 2 is connected to one aquaculture pond 1 via a pipe. The bottom water in aquaculture pond 1, containing a large amount of impurities, enters the vertical flow sedimentation tank 2 through the lower outlet pipe 14. The vertical flow sedimentation tank 2 is used for gravity sedimentation of larger suspended solids with a particle size of 20-100 micrometers and above, such as suspended particles, uneaten feed, excrement, and other organic debris, which can effectively reduce the total amount of suspended solids in the water. The bottom of the vertical flow sedimentation tank 2 is connected to the main sewage pipe 10. The impurities settled by the vertical flow sedimentation tank 2 are discharged into the main sewage pipe 10 after regular cleaning. The outlets of all vertical flow sedimentation tanks 2 are connected to a main pipe for collection, and then connected to the microfiltration tank 3. The water that has been settled by the vertical flow sedimentation tank 2 enters the microfiltration tank 3 for filtration.

[0035] The microfiltration tank 3 is used to remove small particulate matter with a particle size of 10-60 micrometers, such as feed residue, fish feces, dead aquatic organisms, and silt, from the water through mechanical filtration, thereby reducing the organic load in the water. The microfiltration tank 3 is equipped with a microfilter 31, which is connected to the upper outlet pipe 12 and the vertical flow sedimentation tank 2. The microfilter 31 has a rotating drum with a filter screen of 150-250 mesh. The rotating drum is driven by a motor, which can be controlled by timer or liquid level. The rotating drum can intercept small particulate impurities in the water. The sewage discharge mechanism of the microfilter 31 is connected to the main sewage pipe 10 and collects the impurities separated by the filter screen and discharges them into the main sewage pipe 10, thereby achieving the purpose of filtration. The filtered water enters the biochemical flotation tank 4 for purification treatment. Furthermore, the microfilter 31 is equipped with a backwashing device, which can periodically flush the rotating drum to ensure the filtration effect.

[0036] The biochemical flotation tank 4 is connected to the microfilter 31 via a pipeline. The biochemical flotation tank 4 includes a flotation chamber 41 and a pump chamber 42. The flotation chamber 41 and the pump chamber 42 are an integrated open box structure. The flotation chamber 41 and the pump chamber 42 are separated by a siphon mechanism. The biochemical flotation tank 4 is connected to a biochemical chamber 43 and a denitrification chamber 44. The biochemical chamber 43 is connected to the front end of the flotation chamber 41 via a pipeline. The denitrification chamber 44 is connected to the biochemical chamber 43 via a pipeline. The denitrification chamber 44 is connected to the rear end of the flotation chamber 41 via a pipeline. The flotation chamber 41, the biochemical chamber 43, and the denitrification chamber 44 form a circulation structure. Preferably, a pump body is installed on the connecting pipeline between each pair of the flotation chamber 41, the biochemical chamber 43, and the denitrification chamber 44, so that the water can circulate among the flotation chamber 41, the biochemical chamber 43, and the denitrification chamber 44.

[0037] Approximately one-tenth of the water volume at the front end of the flotation tank 41 flows into the biochemical chamber 43. The biochemical chamber 43 is used to degrade ammonia nitrogen and nitrite in the water, converting them into relatively non-toxic nitrate. The bottom of the biochemical chamber 43 is equipped with a microporous aeration disc array. The aeration discs employ an intermittent aeration mode to promote deep oxygen penetration into the biofilm, maintaining an air-to-water ratio (cubic meters of air / cubic meters of water) of 3:1. The biochemical chamber 43 contains biological packing material, including three-dimensional elastic packing, porous ceramic rings, and suspended biological balls. The three-dimensional elastic packing is made of polyethylene material with a specific surface area >800 m². 2 / m 3 The three-dimensional elastic packing material is vertically suspended, with a filling rate controlled at 60-70%. The porous ceramic rings are stacked above the aeration zone at the bottom of the tank. The pore size of the porous ceramic rings is 0.5-1 cm, providing a micro-aerobic environment and promoting the stratified distribution of bacterial communities. The suspended biospheres are suspended in the water; their hollow interiors with ribs allow them to tumble with the water flow, increasing contact efficiency. The suspended biospheres occupy 30% of the water volume, and the biological packing material can provide more than 1000 m³ of aeration. 2 / m 3 The total specific surface area forms a stable biofilm carrier. During the biofilm formation period, potassium dihydrogen phosphate (PO4) is added. 3 - (N = 1:100) to avoid phosphorus limitation, while submitting trace amounts of Fe. 2+ Mo 2+ Promotes enzyme activity, Fe 2+ Mo 2+ The concentration is controlled at 0.1 mg / L. The biochemical chamber 43 is filled with nitrifying bacteria, which are attached to the packing material. The nitrifying bacteria include, but are not limited to, one or more of the following: Sulfidomonas sulfidans, Nitrifying Bacillus, Nitrifying Bacillus, Nitrifying Spirochetes, and heterotrophic nitrifying bacteria. They effectively degrade ammonia nitrogen and nitrite in the water and convert them into relatively non-toxic nitrates, thus maintaining the ecological balance of the water body. The pH value in the biochemical chamber 43 is maintained at 7.2-7.8. The alkalinity is maintained by regular monitoring and by adding sodium bicarbonate when necessary.

[0038] The denitrification chamber 44 is used to convert nitrates and nitrites in the purified water into nitrogen gas or to oxidize nitrite. The denitrification chamber 44 is a cylindrical, sealed chamber with an effective volume 1.2 times that of the biological chamber 43. The denitrification chamber 44 is equipped with packing material, including: volcanic rock particles with a particle size of 3-5 cm at the bottom of the chamber, which provide iron and other trace elements; and porous polyethylene suspended balls with a diameter of 10 cm and a specific surface area of ​​300 m² suspended in the water. 2 / m 3The denitrification chamber 44 contains denitrifying bacteria, including one or more of *Pseudomonas schlegelii*, *Pseudomonas putida*, *Paracoccus*, and *Thiobacillus denitrifyingus*. The denitrification chamber 44 is connected to a carbon source addition device, preferably a sodium acetate solution storage tank and a metering pump. The carbon source addition device automatically adjusts the amount of sodium acetate solution added according to the nitrate concentration of the influent. Under the action of the denitrifying bacteria, nitrate nitrogen and nitrite nitrogen in the water can be converted into nitrogen gas or nitrous oxide, which is then discharged from the water into the air. The specific path is: C2H3O2 - (acetate) + NO3 - →N2+CO2+OH - +H2O; The water stays in the biological chamber 43 for 2 hours. After denitrification, the water is returned to the rear end of the biological chamber 43 and flows to the pump chamber 42. The water completes the treatment of the entire biological flotation tank 4 within 1 day.

[0039] like Figure 5As shown, the siphon mechanism includes a first siphon plate 45 and a second siphon plate 46. The first siphon plate 45 is vertically installed at the bottom of the biochemical flotation tank 4, and its height is three-quarters of the height of the biochemical flotation tank 4. The second siphon plate 46 is vertically installed at its top, and its height is two-thirds of the height of the biochemical flotation tank 4. The first siphon plate 45 and the second siphon plate 46 are arranged at a certain distance, and their projection directions are aligned. With a certain overlap, when the water in the flotation chamber 41 is higher than the height of the first siphon plate 45, it will enter the pump chamber 42 through the gap between the first siphon plate 45 and the second siphon plate 46. The bottom of the flotation chamber 41 has an inclined surface, the lowest end of which is located at the installation position of the first siphon plate 45. The inclined surface is used to discharge the sedimented impurities. The impurities in the water in the flotation chamber 41 settle onto the inclined surface and fall to the bottom of the inclined surface under the influence of gravity and water flow. A drain pipe is installed at the bottom of the inclined surface. Connected to the main sewage pipe 10, the precipitated impurities are discharged into the main sewage pipe 10; an aeration pipe 411 is installed on the inclined surface at the bottom of the flotation chamber 41, and the aeration pipe 411 is connected to an external air pump. The aeration pipe 411 pumps compressed air into the water, dissolving the air in the water to form microbubbles, thereby floating suspended solids, plankton, and oils to the water surface, while removing some ammonia nitrogen from the water, which is then floated to the surface by the bubbles in the water; a pump chamber 42 is also provided with a The inclined plane has a drain pipe at its bottom end, which is connected to the main drain pipe 10. The sedimented impurities are discharged into the main drain pipe 10. The pump chamber 42 is connected to the sand filter 5, the nano denitrification system 6 and the multi-stage stripping system 7 through pipes. The pipes connecting the pump chamber 42 to the sand filter 5, the nano denitrification system 6 and the multi-stage stripping system 7 are equipped with circulation pumps 421, so that the water can flow back and forth between the pump chamber 42 and the sand filter 5, the nano denitrification system 6 and the multi-stage stripping system 7.

[0040] The sand filter 5 is used to filter out suspended particles, organic matter, plankton, and other impurities in the water through physical filtration, thereby improving water quality. The sand filter 5 forms a circulation system with the pump chamber 42 via the circulation pump 421. Water in the pump chamber 42 enters the sand filter 5 through the circulation pump 421. After the sand filter 5 completes physical filtration, it is pumped back to the pump chamber 42 via the circulation pump 421, completing one circulation cycle. The sand filter 5 is a commonly used sand filter device on the market. It mainly uses the physical interception of quartz sand to effectively remove tiny suspended particles and impurities in the water, with a filtration accuracy of 20-50 microns, making the water clear and transparent. The lower end of the sand filter 5 is connected to the main drain pipe 10. The sand filter 5 has automatic flushing and sewage discharge functions. When impurities accumulate to a certain level, the flushing device will be automatically activated to discharge the impurities, reducing the frequency of manual intervention.

[0041] The nano-denitrification system 6 is used to degrade nitrite, ammonia nitrogen, and eradicate viruses in water. The nano-denitrification system 6 includes an ozone generator 61, a jet pump 62, a nano-jet injector 63, and a mixing tower 64. The mixing tower 64 is connected to the pump chamber 42 via a pipe. The ozone generator 61 is installed on the pipe connecting the pump chamber 42 and the mixing tower 64. The nano-jet injector 63 is connected to the pipe. The jet pump 62 is connected to the nano-jet injector 63 and is used to transport aquaculture water to power the nano-jet injector 63. The ozone generator 61 provides an ozone source to remove ammonia nitrogen and nitrite from the water. During the operation of the jet pump 62, the ozone generated by the ozone generator 61 is introduced into the water. The nano-jet injector 63 thoroughly mixes the ozone provided by the ozone generator 61 with the water, ensuring that the ozone molecules in the water reach the nanoscale. It can fully mix with water, prolonging the residence time in the water and improving nitrogen removal efficiency. The mixing tower 64 has a water tower-like structure with a sufficiently large internal stagnant space. An inlet pipe 641 is installed at the top of the mixing tower 64. The nano-jet nozzle 63 is connected to the inlet pipe 641 of the mixing tower 64 via a pipe. Water mixed with ozone enters the mixing tower 64 through the inlet pipe 641, which extends to the lower middle part of the mixing tower 64. An outlet pipe 642 is installed at the lower end of the mixing tower 64. The outlet pipe 642 is located inside the mixing tower 64, bending vertically upwards, with its outlet located in the upper middle part of the mixing tower 64. The design of the inlet pipe 641 and the outlet pipe 642 ensures sufficient contact and reaction time between ozone and the aquaculture water within the mixing tower 64, ensuring the removal of ammonia, nitrite, and harmful substances such as pathogens in the aquaculture water. The reaction principle is as follows:

[0042] 1. Ammonia nitrogen (NH3 / NH4) + Removal of )

[0043] (1) Direct oxidation: Ozone (O3) can directly oxidize ammonia nitrogen to produce nitrate (NO3). - It reacts with nitrogen (N2), but the reaction rate is slow and requires a high concentration of ozone.

[0044] 2NH3+4O 3 →NO 3- +N 2 +4O2+2H + +H2O

[0045] (2) Indirect oxidation (main pathway):

[0046] Ozone (O3) decomposes in water to produce hydroxyl radicals (·OH), which have a stronger oxidizing power (oxidation potential 2.8V) and can gradually oxidize ammonia nitrogen to nitrite (NO2). - ) and nitrates (NO3) - );

[0047] 2. Nitrite (NO2) - Removal of )

[0048] Ozone (O3) directly oxidizes nitrite to nitrate (NO3). - ), reacted quickly:

[0049] NO 2 +O 3 →NO 3- +O 2

[0050] This process can rapidly reduce nitrite toxicity, especially in high-density aquaculture;

[0051] 3. Nitrates (NO3) - Removal of )

[0052] Because ozone (O3) cannot directly degrade nitrates (NO3). - Because of its stable chemical properties, nitrates in circulating water need to be converted into nitrogen gas and discharged through a biochemical denitrification process. Ozone can directly oxidize cell structures, killing pathogens by oxidizing lipoproteins and phospholipids on microbial cell membranes, oxidizing key enzymes, and attacking DNA / RNA bases. At the same time, ozone decomposes in water to produce hydroxyl radicals (·OH), further enhancing the oxidation effect and killing pathogens.

[0053] The outlet pipe 642 is connected to the pump chamber 42 via a pipeline. The jet pump 62 draws water from the pump chamber 42, ensuring that the pressure in the connecting pipeline between the jet pump outlet and the nanojet device is not less than 1.0 Bar. This is to allow for more thorough mixing of ozone and water within the nanojet device under high pressure, further improving water purification efficiency. The water, thoroughly mixed with ozone by the nanojet device, enters the mixing tower 64. The ozone-mixed water undergoes a complete reaction within the mixing tower 64 to remove ammonia nitrogen, nitrite, bacteria, and other substances before returning to the pump chamber 42 through the pipeline, completing one cycle. An exhaust pipe 643 is also installed at the top of the mixing tower 64 to discharge excess ozone from the tower.

[0054] The multi-stage stripping system 7 is used to strip residual ozone, excess carbon dioxide, and nitrogen from the water into the air, such as... Figure 7 , Figure 8 As shown, the multi-stage stripping system 7 includes a stripping tower, which consists of a cylindrical tower body 71 and a top cover 72 installed at the top of the tower body 71. The tower body 71 has a reflux space, and a stripping water inlet pipe 73 is provided at its bottom end. The stripping water inlet pipe 73 is connected to a pump chamber 42 via a pipe. Water in the pump chamber 42 is pumped into the tower body 71 by a circulating pump 421. The stripping tower is provided with a packing layer 74 and a water distributor 75. The water distributor 75 is located at the upper end of the tower body 71. The stripping water inlet pipe 73 enters the tower body 71 and extends upward to connect with the water distributor 75. Figure 9 As shown, the water distributor 75 is composed of multiple perforated pipes 751. The shape of the perforated pipes can be arranged according to actual conditions to achieve uniform water distribution. For example, in this embodiment, the water distributor 75 is composed of four perforated pipes 751 arranged in a grid structure. Water in the pump chamber 42 enters the water distributor 75 through the blow-off inlet pipe 73, flows out from the small holes of the water distributor 75, and drips in droplets. The packing layer 74 is located below the water distributor 75. The packing layer 74 is composed of multi-faceted hollow spherical packing 741 and a packing base 742. The hollow spherical packing 741 is placed on the packing base, as shown. Figure 10As shown, the surface of the hollow sphere packing 741 has several regular or irregular planes, such as rhombuses and triangles, pieced together to form an uneven texture. The interior of the multifaceted hollow sphere packing 741 is hollow, which reduces the weight of the sphere while maintaining a certain strength. The spherical structure increases the solid-liquid contact area, meaning that when water comes into contact with the hollow sphere, it will impact the various surfaces of the hollow sphere multiple times. This facilitates the rapid release of gases such as ozone, carbon dioxide, and nitrogen from the water, which are then discharged through the outlet. Simultaneously, it promotes turbulence, which is achieved through the uneven texture of the multifaceted hollow sphere. The surface disturbs the fluid, reducing laminar flow and enhancing mixing. The gaps between the spherical packings have low resistance, thus optimizing the pressure when water passes through, resulting in energy efficiency. A discharge port 76 is evenly distributed along the circumference of the upper middle part of the stripping tower's perimeter. Ozone, carbon dioxide, nitrogen, and other gases released from the water are discharged from the stripping tower through the discharge port 76. Preferably, a fan is installed in the upper part of the tower body 71 to facilitate the blowing out of the gases inside the tower body 71. A stripping drain pipe 711 is installed at the lower end of the tower body 71 to discharge the denitrified water from the stripping tower. The circulating pump 421 pumps the water in the pump chamber 42 to the stripping inlet pipe 73, where it is evenly distributed by the water distributor 75 and enters the multi-faceted packing layer 74. There, it collides fully with the surface area of ​​the multi-faceted hollow spheres, causing gases such as ozone, carbon dioxide, and nitrogen to be released from the water. The degassed water is then discharged from the drain outlet. Multiple stripping towers can be used as needed; for example, multiple stripping towers can be connected in parallel to significantly improve the purification rate. To balance the pH value of the water in the tower body 71, the stripping tower is connected to a pH adjustment mechanism, which includes components connected to the tower body 71. The automatic acid / alkali adding device 77 and a pH sensor (not shown) installed inside the tower body 71 are included. The automatic acid / alkali adding device 77 can add acid or alkali to the tower body 71 to balance the pH value of the water inside the tower body 71. When the pH sensor detects that the pH reaches 8, the automatic acid / alkali adding device 77 is activated to add acid to the tower body 71 until the pH of the water inside the tower body 71 is adjusted to 7. If the pH of the water inside the tower body 71 is detected to reach 6.5, the automatic acid / alkali adding device 77 is activated to add alkali to the tower body 71 until the pH is adjusted to 7.

[0055] The aquaculture system also includes a balancing tank 8. One end of the balancing tank 8 is connected to the blow-off drain pipe 711 via a pipe, and the other end is connected to each aquaculture pond 1 via a pipe. The balancing tank 8 is used to balance the water volume, and most importantly, it uses the liquid level difference to press the water back to each aquaculture pond 1. A constant temperature system 9 is installed in the balancing tank 8. The constant temperature system 9 includes a temperature sensor, a heater, and a cooler. The temperature sensor is electrically connected to the heater and the cooler. The temperature sensor is used to monitor the temperature of the water in the balancing tank 8. When the water temperature in the balancing tank 8 is too low, the heater is activated to heat the water in the balancing tank 8. When the water temperature is too high, the cooler is activated to cool the water in the balancing tank 8, thereby achieving a constant water temperature.

[0056] The method of using the novel freshwater fish factory-scale recirculating aquaculture system provided by this utility model is as follows:

[0057] 1. The bottom water in the aquaculture pond 1, containing a large amount of impurities, enters the vertical flow sedimentation tank 2 through the lower outlet pipe 14. The vertical flow sedimentation tank 2 settles larger suspended solids such as suspended particles, uneaten feed, excrement and other organic debris in the aquaculture water by gravity. The settled impurities are discharged into the main sewage pipe 10. The water after sedimentation in the vertical flow sedimentation tank 2 enters the microfiltration tank 3 for filtration.

[0058] 2. The middle and upper layers of water in the aquaculture pond 1 enter the upper outlet pipe 12 through the central pipe 11. The upper outlet pipe 12 is connected to the microfiltration tank 3, and the water is transported to the microfiltration tank 3 for filtration through the upper outlet pipe 12.

[0059] 3. The microfilter in the microfilter tank 3 removes small particulate matter in the water through mechanical filtration, such as feed residue, fish feces, dead aquatic organisms, silt, etc., and guides the impurities separated by the filter screen to the bottom of the drum and into the main sewage pipe 10 for discharge. The filtered water enters the biochemical flotation tank 4 for purification treatment.

[0060] 4. After being filtered by the microfiltration machine, the water enters the flotation chamber 41. The aeration pipe 411 in the flotation chamber 41 pumps compressed air into the water. By dissolving the air into the water, tiny bubbles are formed, which float suspended solids, plankton, and oil to the water surface. At the same time, ammonia nitrogen in the water is removed and floated to the water surface and discharged by the bubbles in the water.

[0061] 5. Part of the water at the front end of the flotation tank 41 flows into the biological treatment chamber 43. The nitrifying bacteria in the biological treatment chamber 43 degrade ammonia nitrogen and nitrite in the water and convert them into relatively non-toxic nitrate. The water treated by nitrification flows into the denitrification chamber 44. Under the action of denitrifying bacteria, the water in the denitrification chamber 44 can convert nitrate nitrogen and nitrite in the water into nitrogen gas or nitrous oxide, which is discharged from the water into the air, thereby eliminating ammonia nitrogen. The water treated by denitrification is returned to the rear end of the biological treatment chamber 43.

[0062] 6. After the water level in the flotation chamber 41 reaches a certain height, it enters the pump chamber 42 through the siphon mechanism; the water in the pump chamber 42 enters the sand filter 5 through the circulation pump 421. After the sand filter 5 completes physical filtration, it effectively removes small suspended particles and impurities in the water, and then pumps it into the pump chamber 42 through the circulation pump 421 to complete one cycle of treatment.

[0063] 7. After the sand filter 5 completes physical filtration, the jet pump 62 draws water from the pump chamber 42. After the ozone is fully mixed with the water by the nano jet injector 63, the ozone nano bubble mixture is injected into the mixing tower 64. The water mixed with ozone undergoes a full reaction in the mixing tower 64 to remove substances such as ammonia nitrogen, nitrite, and bacteria from the water. Then, it is returned to the pump chamber 42 through the pipeline to complete one cycle of treatment.

[0064] 8. The circulating pump 421 pumps the water in the pump chamber 42 after it has been treated by the mixing tower 64 to the stripping inlet pipe 73 of the stripping tower. The circulating pump 421 pumps the water in the pump chamber 42 to the stripping inlet pipe 73 of the stripping tower. The water is evenly distributed by the water distributor and enters the multi-faceted hollow sphere packing layer. It fully collides with the surface area of ​​the multi-faceted hollow spheres, so that the ozone, carbon dioxide, nitrogen and other gases in the water are separated from the water. The degassed water is discharged from the drain outlet and enters the balance tank 8 after denitrification.

[0065] 9. The temperature sensor in the balance tank 8 monitors the water temperature in the balance tank 8 in real time. When the water temperature in the balance tank 8 is too low, the heater is activated to heat the water in the balance tank 8. When the water temperature is too high, the cooler is activated to cool the water in the balance tank 8, thereby achieving a constant water temperature. The balance tank 8 then uses the liquid level difference to press the water back to each aquaculture tank 1 to complete the entire water purification cycle.

[0066] The technical effects achieved by this utility model are as follows:

[0067] index Existing technology This utility model Energy consumption <![CDATA[0.5kW·h / m 3 ]]> <![CDATA[0.33kW·h / m 3 ]]> Total nitrogen removal rate 40％ 96％ System footprint <![CDATA[2㎡ / m 3 Aquaculture water bodies <![CDATA[1.7㎡ / m 3 Aquaculture water bodies mandarin fish farming density <![CDATA[20-30kg / m 3 Aquaculture water bodies <![CDATA[>40kg / m 3 Aquaculture water bodies Sea bass farming density <![CDATA[30-40kg / m 3 Aquaculture water bodies <![CDATA[>50kg / m 3 Aquaculture water bodies Murray cod farming density <![CDATA[30-40kg / m 3 Water bodies <![CDATA[>50kg / m 3 Aquaculture water bodies Water replenishment 10-20% of total circulating volume per day <3% of the total circulating water volume per day

[0068] As can be seen from the table above, the freshwater fish recirculating aquaculture system provided in this application, by constructing a multi-stage synergistic treatment system and introducing a denitrification system, increases the total nitrogen removal rate of the aquaculture system to 96%, which is 140% higher than that of traditional systems. At the same time, it reduces the system's water replenishment, reducing the daily water replenishment to less than 3%, and achieving a water saving rate of over 70% in the total circulating water volume. This completely reconstructs the efficiency standards of recirculating aquaculture and breaks through the bottleneck of high-density aquaculture—the stocking density of mandarin fish, bass, and Murray cod can be increased to >40 kg / m³. 3 >50kg / m 3 and >50kg / m 3 This significantly improves breeding efficiency while also significantly reducing energy consumption by 34%, and also reduces the footprint by 15%, resulting in a substantial reduction in operating costs.

[0069] This invention, by constructing a multi-level collaborative treatment system, can increase the nitrogen oxide removal rate in aquaculture water to over 95%. Simultaneously, through nano-air flotation ionization technology, it shortens the denitrification time to 1.5 hours. This significantly reduces the volume of the biological treatment tank and effectively kills viruses and insect eggs in the aquaculture water, greatly reducing the adverse effects of viruses and pests. This invention further optimizes the water quality of aquaculture water, thereby increasing the stocking density of various fish species by 20% or more.

[0070] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural transformations made based on the contents of the present utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present utility model.

Claims

1. A novel freshwater fish factory-scale recirculating aquaculture system, comprising a culture pond (1), a vertical flow sedimentation tank (2), a microfiltration tank (3), a biochemical flotation tank (4), a sand filter (5), a nano-denitrification system (6), a multi-stage stripping system (7), and a balancing tank (8), characterized in that: The aquaculture pond (1) is connected to the vertical flow sedimentation tank (2) and the microfiltration tank (3) respectively. The vertical flow sedimentation tank (2) is connected to the microfiltration tank (3). The biochemical flotation tank (4) is connected to the microfiltration tank (3) through a pipe. The biochemical flotation tank (4) is connected to the sand filter (5), the nano nitrogen removal system (6), and the multi-stage stripping system (7) through pipes respectively. The multi-stage stripping system (7) is connected to the balance tank (8) through a pipe. The multi-stage stripping system (7) includes a stripping tower, which consists of a cylindrical tower body (71) and a top cover (72) installed on the top of the tower body (71). The tower body (71) has a stagnant space, and a stripping inlet pipe (73) is provided at its bottom end. The stripping inlet pipe (73) is connected to the pump chamber (42) through a pipe. Water in the pump chamber (42) is pumped into the tower body (71) by the circulating pump (421). The stripping tower is equipped with a packing layer (74) and a water distributor (75). The water distributor (75) is located at the upper end of the tower body (71). The stripping inlet pipe (73) enters the tower body (71) and extends upward to connect with the water distributor (75). The packing layer (74) is located below the water distributor (75). A vent (76) is evenly opened along the circumference of the upper middle part of the stripping tower wall. A blower is installed in the upper part of the tower body (71). A stripping drain pipe (711) is installed at the lower end of the tower body (71). The stripping drain pipe (711) is connected to the balance tank (8) through a pipe. The balance tank (8) is connected to the aquaculture tank (1) through a pipe.

2. The novel freshwater fish factory-style recirculating aquaculture system according to claim 1, characterized in that: The aquaculture ponds (1) are provided in multiple ways, and the multiple aquaculture ponds (1) are arranged in an array. The vertical flow sedimentation tanks (2) are provided in multiple ways, and the number of vertical flow sedimentation tanks (2) is the same as the number of aquaculture ponds (1). One vertical flow sedimentation tank (2) is connected to one aquaculture pond (1) through a pipe.

3. The novel freshwater fish factory-style recirculating aquaculture system according to claim 1, characterized in that: A central pipe (11) is provided at the center of the bottom surface of the aquaculture pond (1). A water outlet sleeve (13) is connected to the axial position of the bottom surface of the aquaculture pond (1). The water outlet sleeve includes an upper water outlet pipe (12), a lower water outlet pipe (14), and a sleeve mounting platform (15). The sleeve mounting platform (15) is installed at the center of the bottom surface of the aquaculture pond (1). An upper water outlet (151) and a lower water outlet (152) are provided on the sleeve mounting platform (15). The upper water outlet pipe (12) is connected to the lower end of the upper water outlet (151), and the lower water outlet pipe (14) is connected to the lower end of the lower water outlet (152). The lower end of the central pipe (11) is connected to the lower end of the lower water outlet (152), and the lower end of the central pipe (11) is installed on the upper water outlet (151) and connected to the upper water outlet pipe (12). The upper water outlet pipe (12) is connected to the microfiltration tank (3). A protective cover (112) is provided at the lower end of the central pipe (11). The lower end of the protective cover (112) is fastened to the bottom surface of the aquaculture tank (1). Several sewage holes (113) are opened at the lower end of the protective cover (112). The lower water outlet (152) is set to open upwards. The lower water outlet pipe (14) is connected to the vertical flow sedimentation tank (2).

4. The novel freshwater fish factory-style recirculating aquaculture system according to claim 1, characterized in that: The biochemical flotation tank (4) is connected to the microfiltration tank (3) via a pipeline. The biochemical flotation tank (4) includes a flotation chamber (41) and a pump chamber (42). The flotation chamber (41) and the pump chamber (42) are an integrated closed box structure. The flotation chamber (41) and the pump chamber (42) are separated by a siphon mechanism. The siphon mechanism includes a first siphon plate (45) and a second siphon plate (46). The first siphon plate (45) is vertically installed in the biochemical flotation tank (4). At the bottom, the height of the first siphon plate (45) is three-quarters of the height of the biochemical flotation tank (4). The second siphon plate (46) is vertically installed at the top of the second siphon plate (46). The height of the second siphon plate (46) is two-thirds of the height of the biochemical flotation tank (4). The first siphon plate (45) and the second siphon plate (46) are set at a certain distance, and the first siphon plate (45) and the second siphon plate (46) have a certain area overlap in the projection direction.

5. The novel freshwater fish factory-style recirculating aquaculture system according to claim 4, characterized in that: The air flotation chamber (41) has a slope at the bottom, and the lowest end of the slope is located at the installation position of the first siphon plate (45). An aeration pipe (411) is installed on the slope at the bottom of the air flotation chamber (41). An inclined surface is also provided in the pump chamber (42), and a sewage pipe is provided at the bottom end of the inclined surface.

6. The novel freshwater fish factory-style recirculating aquaculture system according to claim 1, characterized in that: The water distributor (75) consists of multiple perforated tubes (751).

7. The novel freshwater fish factory-style recirculating aquaculture system according to claim 1, characterized in that: The packing layer (74) is composed of multi-faceted hollow sphere packing (741) and packing base (742). The hollow sphere packing (741) is placed on the packing base. The surface of the hollow sphere packing (741) has several regular or irregular planes, which are spliced ​​together to form an uneven texture. The interior of the multi-faceted hollow sphere packing (741) is hollow.

8. The novel freshwater fish factory-style recirculating aquaculture system according to claim 1, characterized in that: The stripping tower is connected to a pH adjustment mechanism, which includes an automatic acid and alkali addition device (77) connected to the tower body (71) and a pH sensor installed inside the tower body (71).

9. The novel freshwater fish factory-style recirculating aquaculture system according to claim 1, characterized in that: The balance tank (8) is equipped with a constant temperature system (9), which includes a temperature sensor, a heater and a cooler. The temperature sensor is electrically connected to the heater and the cooler.

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