An industrialized fish-algae recirculating aquaculture system and method

Abstract

The present invention provides an industrialized fish-algae recirculating aquaculture system and method, belonging to the technical field of recirculating aquaculture; the industrialized fish-algae recirculating aquaculture system includes a fish-algae aquaculture system, a fiber rotary disk filtration system and a magnetic loading flocculation system; the fish-algae aquaculture system can realize the co-culture of fish and algae in the same space, and the algae can convert nutrients such as CO2 exhaled by fish, nitrogen and phosphorus in the aquaculture water body into its own substances such as proteins, polysaccharides, vitamins and lipids, and release oxygen, rapidly improving the aquaculture water quality; the fiber rotary disk filtration system and the magnetic loading flocculation system can effectively remove suspended particles, oils, algae, bacteria, viruses, etc. in the aquaculture sewage, realizing the deep purification of the aquaculture sewage, and the purified water quality meets the fishery aquaculture standard and can be directly recycled, and there is no sewage discharge in the whole system. The industrialized fish-algae recirculating aquaculture system and method of the present invention can realize high-density, high-stability and low-energy-consumption recirculating aquaculture.

Description

Technical Field

[0001] The present invention belongs to the technical field of recirculating aquaculture, and particularly relates to an industrial fish-algae recirculating aquaculture system and method. Background Art

[0002] The recirculating aquaculture system is a new type of aquaculture model that treats aquaculture wastewater through a series of water treatment units and then recycles it. The recirculating aquaculture system uses engineering technology and facilities and equipment to remove harmful pollutants in the water body and purify the water environment. It not only solves the problem of low water resource utilization but also provides a stable and high-quality environment for fish farming, providing favorable conditions for high-density farming.

[0003] Microalgae can convert inorganic nitrogen and phosphorus nutrients such as NH4 + -N, NH3-N, NO2 - -N, NO3 - -N, PO4 3- -P in the sewage into the own substances of algal cells such as proteins, polysaccharides, fats, vitamins, and nucleic acids through photosynthesis. The sewage treatment technology based on microalgae cultivation can simultaneously achieve sewage purification, nutrient recovery, and the output of high-value biomass. This technology has been applied to treat aquaculture sewage. For example, Chinese Patent CN 112931366 A discloses a microalgae-driven high-density intensive aquatic product ecological aquaculture system and method and applications. In this method, the tail water generated in the fish farming area is received for the cultivation of bacteria and microalgae, and the algal liquid rich in microalgae biomass obtained from the cultivation is used as bait for shellfish farming. In this method, the tail water generated from fish farming is purified by microalgae and bacteria in a different location, but the tail water generated from fish farming is not recycled for fish farming.

[0004] Strictly speaking, the system design is not mature enough, the equipment stability is poor, and the contents of NH4 + -N, NH3-N, NO2 - -N in the water body cannot be effectively controlled and must be solved by a large amount of water change, and discharge is inevitable. Summary of the Invention

[0005] In view of this, the purpose of the invention is to provide an industrial fish-algae recirculating aquaculture system and method that can realize the recycling of aquaculture sewage.

[0006] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides an industrial fish-algae recirculating aquaculture system, including: a fish-algae aquaculture system, a fiber rotary disk filtration system, and a magnetic loading flocculation system;

[0008] The fish-algae cultivation system includes a fishpond body, a water inlet system, and a water outlet system;

[0009] The fiber rotary disk filtration system includes a first fiber rotary disk filtration system and a second fiber rotary disk filtration system; the first fiber rotary disk system is located in the first filtration tank; the second fiber rotary disk filtration system is located in the second filtration tank; the first fiber rotary disk filtration system and the second fiber rotary disk filtration system respectively include fiber rotary disk filters, backwashing systems, sludge discharging systems, and supporting electrical control systems; the filtration fluxes of the first fiber rotary disk filtration system and the second fiber rotary disk filtration system for the same aquaculture wastewater are equal; the filtration aperture of the filter cloth in the first fiber rotary disk filter is 15 - 30 μm; the filtration aperture of the filter cloth in the second fiber rotary disk filter is 1 - 5 μm; a filtered water collection tank is arranged between the first filtration tank and the second filtration tank; the filtered water collection tank is provided with a filtered water outlet; the first fiber rotary disk filtration system and the second fiber rotary disk filtration system share the filtered water collection tank, the filtered water outlet, the backsuction pump, and the sewage suction pipe;

[0010] The water outlet system of the fish-algae cultivation system is connected to the first filtration tank and the second filtration tank respectively through pipelines;

[0011] The filtered water outlet of the fiber rotary disk filtration system is connected to the water inlet system of the fish-algae cultivation system through a pipeline;

[0012] The sewage outlet of the fiber rotary disk filtration system is connected to the water inlet of the magnetic loading flocculation system through a pipeline;

[0013] The magnetic loading flocculation system includes a mixing tank, a coagulation tank, a flocculation tank, a sedimentation tank, a magnetic powder recovery device, and a sludge dewatering device;

[0014] The sedimentation tank of the magnetic loading flocculation system is provided with a clarified water outlet; the clarified water outlet is connected to the first filtration tank and the second filtration tank respectively through pipelines.

[0015] Preferably, the water inlet system includes a plurality of water inlet pipes, the water inlet pipes are distributed on the side wall of the fishpond body, and the fishpond water inlets are arranged at equal intervals in the tangential direction.

[0016] Preferably, the fiber rotary disk filter includes a central drum and a rotary disk; the rotary disk is fixed around the central drum and is connected to the central drum through a communication hole; filter cloths are installed on both sides of the rotary disk; the filtration fluxes of the first fiber rotary disk filtration system and the second fiber rotary disk filtration system for the same aquaculture wastewater are equal.

[0017] Preferably, the sludge discharging system includes sludge discharging pipes respectively arranged at the bottoms of the first filtration tank and the second filtration tank, the sludge discharging pipes are connected to the backsuction pump through pipelines; electric valves are respectively arranged on the sludge discharging pipes in the first filtration tank and the second filtration tank.

[0018] Preferably, the magnetic loading flocculation system includes a mixing tank, a coagulation tank, a flocculation tank, a sedimentation tank, a magnetic powder recovery device and a sludge dewatering device which are connected in sequence.

[0019] The present invention also provides a factory fish-algae circulating water culture method based on the factory fish-algae circulating water culture system described in the above solution, including the following steps:

[0020] 1) Inject water into the fish pond body and add pre-cultured highly active microalgae until the algal density in the culture water body reaches 50 - 1000 mg / L;

[0021] 2) Release fry and feed the fish pond every 3 - 5 hours;

[0022] 3) During the culture process, when the microalgae are at the end of the stable growth stage and about to enter the decline stage, close the first fiber rotary disk filter and open the second fiber rotary disk filter, so that the microalgae can no longer return to the fish pond. The intercepted microalgae enter the magnetic loading flocculation system through the backwashing system for further treatment. Add a certain volume of pre-cultured highly active microalgae to make the algal density in the culture water body reach 50 - 1000 mg / L, and harvest the fish after 150 - 200 days.

[0023] Preferably, the stocking density of the fry in step 1) is 25 - 35 kg / m 3 .

[0024] Preferably, when the culture density in the water body is greater than or equal to 30 kg / m 3 , and less than 60 kg / m 3 , the water inflow and outflow are respectively set to 35 - 45 m 3 / h; when the culture density in the water body is greater than or equal to 60 kg / m 3 , and less than 100 kg / m 3 , the water inflow and outflow are respectively set to 55 - 65 m 3 / h; when the culture density in the water body is greater than or equal to 100 kg / m 3 , and less than 200 kg / m 3 , the water inflow and outflow are set to 70 - 90 m 3 / h.

[0025] Preferably, during the culture process, the dissolved oxygen in the culture water body is 5 - 12 mg / L.

[0026] Preferably, the microalgae can pass through the filter cloth in the first fiber rotary disk filter and cannot pass through the filter cloth in the second fiber rotary disk filter; the microalgae include one or more of Chlorella, Nannochloropsis, Dunaliella, and Chlamydomonas reinhardtii.

[0027] Advantages of the present invention: The factoryized fish-algae recirculating aquaculture system provided by the present invention includes: a fish-algae aquaculture system, a fiber rotary disk filtration system, and a magnetic loading flocculation system; the fiber rotary disk filtration system includes a first fiber rotary disk filtration system and a second fiber rotary disk filtration system; the filtration fluxes of the first fiber rotary disk filtration system and the second fiber rotary disk filtration system for the same aquaculture sewage are the same; the filtration pore size of the filter cloth in the first fiber rotary disk filter is 15 - 30 μm; the filtration pore size of the filter cloth in the second fiber rotary disk filter is 1 - 5 μm; the water outlet system of the fish-algae aquaculture system is connected to the first filtration tank and the second filtration tank respectively through pipelines and electric valves; the filtered water outlet of the fiber rotary disk filtration system is connected to the water inlet system of the fish-algae aquaculture system through a pipeline and a pump; the sewage discharge port of the fiber rotary disk filtration system is connected to the water inlet of the magnetic loading flocculation system; the clarified water outlet of the sedimentation tank of the magnetic loading flocculation system is connected to the first filtration tank and the second filtration tank respectively through pipelines and electric valves. During normal water circulation, the first fiber rotary disk filter with a filtration pore size of 15 - 30 μm is opened, and microalgae can return to the fish pond through the first fiber rotary disk filter for reuse; larger suspended solids such as fish feces and residual baits either directly sink to the bottom of the filtration tank or are intercepted by the filter cloth of the first fiber rotary disk filter, and finally enter the magnetic loading flocculation system through the sludge discharge system or backwashing system for further deep purification treatment. When it is necessary to remove microalgae in the aquaculture water body, the second fiber rotary disk filter with a filtration pore size of 1 - 5 μm is opened for interception, so that the microalgae cannot return to the fish pond and enter the magnetic loading flocculation system through the backwashing system for further purification treatment. In the present invention, the fiber rotary disk filtration system not only can filter, but also has a sedimentation function. Larger suspended solids directly sink to the bottom, significantly reducing the sludge amount on the filter cloth and also greatly reducing the backwashing water volume. In the present invention, the magnetic loading flocculation system can effectively remove substances such as larger suspended solids, macromolecular proteins, and oils in the sewage discharged from the fiber rotary disk filtration system, and can also fully remove smaller microalgae, bacteria, and viruses, etc. The total solid content of the clarified water is less than 2 mg / L, the turbidity is less than 1.0 NTU, and the treatment cost per ton of sewage is about 0.1 yuan. The purified water quality meets the fishery aquaculture standard and can be directly recycled. The whole system has no sewage discharge, and only the water evaporated daily and the water taken away by the solids discharged from the dehydrator need to be replenished into the fish pond regularly.

[0028] The industrialized fish-algae recirculating aquaculture method provided by the present invention allows the aquaculture sewage to selectively pass through the first fiber rotary disk filter or the second fiber rotary disk filter. Among them, the pore size of the filter cloth of the first fiber rotary disk filter allows microalgae to pass through while large-particle-size suspended solids cannot pass through, and the pore size of the filter cloth of the second fiber rotary disk filter does not allow microalgae to pass through. Thus, suspended solids with a particle size larger than the pore size of the filter cloth of the first fiber rotary disk filter, such as fish feces and residual baits, can be quickly removed from the fish pond, while the microalgae can return to the fish pond and be cultured in the fish pond together with the fish. The microalgae convert the CO2 exhaled by the fish, nutrients such as nitrogen and phosphorus dissolved in water, etc. into substances of the microalgae cells themselves, such as proteins, polysaccharides, lipids, vitamins, etc. through photosynthesis, and release oxygen, rapidly improving the aquaculture water quality and significantly reducing the demand for artificial oxygenation. In the present invention, the aquaculture sewage is regarded as a valuable resource. During the co-culture of fish and microalgae in the fish pond, not only the purification of the aquaculture sewage and the recovery of nutrients are realized, but also high-value-added microalgae biomass can be produced.

[0029] In the present invention, the fiber rotary disk filtration system quickly removes the microalgae at the end of the stable growth period from the fish pond, avoiding water quality deterioration caused by microalgae problems. The filtration accuracy of the fiber rotary disk filtration system can reach 1um, and it can filter more than 99% of the suspended solids in the aquaculture sewage, and the total solid content of the filtered water is less than 5mg / L.

[0030] In the present invention, the fiber rotary disk filtration system not only can filter but also has a sedimentation function. The large-particle-size suspended solids in the aquaculture sewage directly sink to the bottom, effectively avoiding water quality deterioration caused by fragmentation, significantly reducing the sludge amount on the filter cloth, and reducing the backwashing water volume. In the present invention, after the aquaculture sewage is treated by the fiber rotary disk system, only 2% - 3% of the sewage accounting for the aquaculture volume needs to be further deeply purified by the magnetic loading flocculation system every day. In the present invention, the magnetic loading flocculation system can fully remove substances such as large-particle-size suspended solids, macromolecular proteins, oils and fats, microalgae, bacteria, and viruses in the sewage. The total solid content of the clarified water is less than 2mg / L, the turbidity is less than 1.0NTU, and the water quality reaches the fishery aquaculture standard; the obtained solids can be used as organic fertilizers, and the treatment cost per ton of sewage is about 0.1 yuan.

[0031] In the present invention, the dominant microalgae can inhibit the rapid proliferation of harmful bacteria in the aquaculture water body, significantly reducing the use of fish drugs during the aquaculture process and realizing green aquaculture in the true sense; in addition, the active functional groups on the surface of the microalgae can also promote the aggregation of extremely small suspended solids, significantly improving the transparency of the aquaculture water body. In the present invention, the reuse rate of the aquaculture sewage can reach 99.8%, and high-density aquaculture of fish can be realized with low energy consumption and high stability. Description of the Drawings

[0032] Figure 1Schematic diagram of a fish farming system, where 1 - aeration cone, 2 - fish pond water inlet, 3 - on-line detection component, 4 - water pump, 5 - fish pond body, 6 - fish pond water outlet, 7 - outlet valve, 8 - fish pond outlet pipe, 9 - inlet pipe;

[0033] Figure 2 Schematic diagram of a fiber rotary disk filtration system and a supporting electrical control system, where 10 - first filtration pond water inlet, 11 - second filtration pond water inlet, 12 - first filtration pond, 13 - second filtration pond, 14 - first fiber rotary disk filtration system, 15 - second fiber rotary disk filtration system, 16 - filtered water collection tank, 17 - filtered water outlet, 18 - supporting electrical control system;

[0034] Figure 3 Schematic diagram of a sludge discharge system, where 10 - first filtration pond water inlet, 11 - second filtration pond water inlet, 12 - first filtration pond, 13 - second filtration pond, 17 - filtered water outlet, 19 - dirt suction port, 20 - reverse suction pump, 21 - dirt suction pipe;

[0035] Figure 4 Schematic diagram of the working principle of a magnetic loading flocculation system, where 22 - sewage inlet, 23 - mixing tank, 24 - coagulation tank, 25 - flocculation tank, 26 - sedimentation tank, 27 - purified water outlet, 28 - magnetic powder recovery device, 29 - sludge dewatering device, 30 - sludge pump. Detailed implementation mode

[0036] The present invention provides an industrialized fish-algae circulating water aquaculture system, including: the fish-algae aquaculture system includes a fish pond body, a water inlet system and a water outlet system; the fiber rotary disk filtration system includes a first fiber rotary disk filtration system and a second fiber rotary disk filtration system; the first fiber rotary disk system is located in the first filtration pond; the second fiber rotary disk filtration system is located in the second filtration pond; the first fiber rotary disk filtration system and the second fiber rotary disk filtration system respectively include a fiber rotary disk filter, a backwashing system, a sludge discharge system and a supporting electrical control system; the filtration fluxes of the first fiber rotary disk filtration system and the second fiber rotary disk filtration system for the same aquaculture sewage are equal; the filtration pore size of the filter cloth in the first fiber rotary disk filter is 15 - 30 μm; the filtration pore size of the filter cloth in the second fiber rotary disk filter is 1 - 5 μm.

[0037] In the present invention, a filtered water collection tank is provided between the first filtration tank and the second filtration tank; the filtered water collection tank is provided with a filtered water outlet; the first fiber rotary disk filtration system and the second fiber rotary disk filtration system share the filtered water collection tank, the filtered water outlet, the reverse suction pump, and the sewage outlet; the water outlet system of the fish-algae cultivation system is respectively communicated with the first filtration tank and the second filtration tank through pipelines; the filtered water outlet of the fiber rotary disk filtration system is communicated with the water inlet system of the fish-algae cultivation system through a pipeline; the sewage outlet of the fiber rotary disk filtration system is communicated with the water inlet of the magnetic loading flocculation system through a pipeline; the magnetic loading flocculation system includes a mixing tank, a coagulation tank, a flocculation tank, a sedimentation tank, a magnetic powder recovery device, and a sludge dewatering device; the sedimentation tank of the magnetic loading flocculation system is provided with a clarified water outlet; the clarified water outlet is respectively communicated with the first filtration tank and the second filtration tank through pipelines.

[0038] In the present invention, the fish-algae cultivation system, the fiber rotary disk filtration system, and the magnetic loading flocculation system work together to achieve zero-emission circulating water aquaculture.

[0039] In the present invention, the fish-algae cultivation system, the fish farming system includes a fish pond body, a water inlet system, and a water outlet system.

[0040] In the present invention, the shape of the fish pond body is cylindrical; the ratio of the diameter to the height of the fish pond body is preferably (9-10):(1-2), more preferably 9.5:1.5; the present invention has no special limitation on the specific diameter and height of the fish pond body, and it is preferably set according to actual aquaculture needs.

[0041] In the specific implementation process of the present invention, the diameter of the fish pond body is preferably 9-10 m, and the height of the fish pond body is preferably 1.45-1.78 m; the fish pond body is preferably made of polypropylene material.

[0042] In the present invention, at a position 30-50 cm away from the top on the side wall of the fish pond body, several through holes are preferably provided, and the function of the through holes is to overflow floating substances such as oil on the water surface.

[0043] In the present invention, the fish farming system preferably includes several fish pond bodies, and the specific number of the fish pond bodies is determined according to aquaculture needs and the site; the several fish pond bodies are connected in parallel; the several fish pond bodies share the water inlet system and the water outlet system.

[0044] In the present invention, the fish farming system includes a water inlet system; the water inlet system includes several water inlet pipes, and the water inlet pipes are communicated with a water pump; each water inlet pipe is provided with a fish pond water inlet along the tangent line of the side wall of the fish pond body, and the number of the fish pond water inlets is preferably 3-4; the fish pond water inlets are preferably arranged at equal intervals, which is more conducive to the formation of a vortex in the center of the fish pond and the stability of the liquid surface.

[0045] In the present invention, the fish and algae cultivation system includes an effluent system; the effluent system is preferably located at the bottom of the fish pond body; the effluent system includes a fish pond outlet and a fish pond effluent pipe; an effluent valve is preferably provided on the fish pond effluent pipe.

[0046] In the present invention, the fish farming system preferably further includes an aeration system; the aeration system preferably includes an aeration cone.

[0047] In the present invention, the fish farming system preferably further includes an on-line detection system for detecting temperature, dissolved oxygen, pH value, ammonia nitrogen and nitrite nitrogen.

[0048] In an embodiment of the present invention, the schematic diagram of the fish farming system is shown in Figure 1 , where 1 - aeration cone, 2 - fish pond inlet, 3 - on-line detection component, 4 - water pump, 5 - fish pond body, 6 - fish pond outlet, 7 - effluent valve, 8 - fish pond effluent pipe, 9 - inlet pipe.

[0049] In the present invention, the fiber rotary disk filtration system includes a first fiber rotary disk filtration system and a second fiber rotary disk filtration system; the first fiber rotary disk system is located in the first filtration tank; the second fiber rotary disk filtration system is located in the second filtration tank; in the present invention, the effluent system of the fish and algae cultivation system flows into the first filtration tank or the second filtration tank by gravity through a pipeline, and an electric valve is preferably provided on the pipeline.

[0050] In the present invention, a first filtration tank inlet is preferably provided on the pool wall of the first filtration tank, and a second filtration tank inlet is preferably provided on the pool wall of the second filtration tank; a filtered water collection tank is preferably provided between the first filtration tank and the second filtration tank, and a filtered water outlet is provided at the bottom of the filtered water collection tank.

[0051] In the present invention, the first fiber rotary disk filtration system and the second fiber rotary disk filtration system respectively include a fiber rotary disk filter, a backwashing system, a sludge discharging system and a supporting electrical control system. In the present invention, the fiber rotary disk filter preferably includes a central drum and a rotary disk; the rotary disk is fixed around the central drum and is communicated with the central drum through a communication hole; filter cloths are installed on both sides of the rotary disk; the base cloth of the filter cloth is preferably polyester fiber, and the fluff on the base cloth is preferably polyamide fiber.

[0052] In the present invention, the filtration fluxes of the first fiber rotary disk filtration system and the second fiber rotary disk filtration system for the same aquaculture sewage are equal to maintain a constant liquid level in the fish pond; the number of rotary disks of the first and second fiber rotary disk filters is determined according to the amount of aquaculture sewage to be treated.

[0053] In the present invention, the filtration pore size of the filter cloth in the first fiber rotary disk filter is 1 to 5 μm, preferably 1 μm; the filtration pore size of the filter cloth in the second fiber rotary disk filter is 15 to 30 μm, preferably 30 μm.

[0054] In the present invention, a filtered water collection tank is provided between the first filtration tank and the second filtration tank; the filtered water collection tank is provided with a filtered water outlet; the first fiber rotary disk filtration system and the second fiber rotary disk filtration system share the filtered water collection tank, the filtered water outlet, the back suction pump and the sewage outlet.

[0055] In the present invention, the water outlet system of the fish and algae cultivation system is communicated with the first filtration tank and the second filtration tank respectively through pipelines.

[0056] In the present invention, the filtered water outlet of the fiber rotary disk filtration system is communicated with the water inlet system of the fish and algae cultivation system through a pipeline, and a water pump is preferably arranged on the pipeline.

[0057] In an embodiment of the present invention, the schematic diagram of the fiber rotary disk filtration system and the supporting electrical control system is as Figure 2 shown, wherein, 10 - the inlet of the first filtration tank, 11 - the inlet of the second filtration tank, 12 - the first filtration tank, 13 - the second filtration tank, 14 - the first fiber rotary disk filtration system, 15 - the second fiber rotary disk filtration system, 16 - the filtered water collection tank, 17 - the filtered water outlet, 18 - the supporting electrical control system.

[0058] In the present invention, the first fiber rotary disk filtration system and the second fiber rotary disk filtration system can operate independently but cannot be started synchronously; the inlets of the first fiber rotary disk filtration system and the second fiber rotary disk filtration system are controlled by electric valves respectively. During normal water circulation, the first fiber rotary disk filtration system with a filtration pore size of 15 to 30 μm is started, and the microalgae can return to the fish pond through the first fiber rotary disk filter for reuse; larger suspended matters such as fish feces and residual baits either sink to the bottom directly or are intercepted by the filter cloth of the first fiber rotary disk filter and enter the magnetic loading flocculation system through the backwashing system or the sludge discharging system for further in-depth purification treatment. When it is necessary to remove the microalgae in the aquaculture water body, the second fiber rotary disk filtration system with a filtration pore size of 1 to 5 μm is started for interception, and the microalgae enter the magnetic loading flocculation system through the backwashing system for further in-depth purification treatment. After the microalgae in the water body are removed, the pre-cultured highly active microalgae need to be added again.

[0059] In the present invention, during the filtration process of the fiber rotary filter system, large-sized suspended solids in the sewage are blocked by the filter cloth, and clean water flows through the filter cloth and flows into the central drum by gravity, and then flows out of the fiber rotary filter system through the filtered water outlet; large-sized suspended solids blocked by the filter cloth, part of which adheres to the filter cloth surface, and the other part sinks to the bottom of the pool. As the number of attached solids on the filter cloth increases, the filtration resistance increases, and the water level of the filter pool gradually rises. When the liquid level reaches the backwashing set value, the matching electrical control system starts the back suction pump and starts the backwashing process. During normal filtration, the rotary disk is in a stationary state, which is conducive to the direct sinking of suspended solids in aquaculture sewage.

[0060] In the present invention, during the backwashing process of the fiber rotary disk filter system, the rotary disk rotates at a speed of about 1r / min, and the matching electrical control system cleans each group of rotary disks in turn by controlling the electric valve connected to the back-suction pump pipeline; the back-suction pump negatively sucks the surface of the filter cloth, and the clean water passing through the filter cloth cleans the filter cloth from the inside to the outside, and the sludge accumulated on the filter cloth is washed off, sequentially passes through the back-suction pump and the sewage outlet, and enters the magnetic loading flocculation system for further deep purification. After all the rotary disks are cleaned, the liquid level in the filter tank returns to normal. Filtration is carried out as usual during the backwashing period, and the backwashing water volume only accounts for about 1% of the filtered water volume.

[0061] In the present invention, the mud discharge system preferably includes mud discharge pipes respectively arranged at the bottom of the first filter tank and the second filter tank, and the mud discharge pipes are connected to the back-suction pump through pipelines; the mud discharge pipes in the first filter tank and the second filter tank are preferably respectively provided with electric valves; the back-suction pump is preferably equipped with an electrical control system, which can start the mud discharge system according to the working conditions.

[0062] In the present invention, the schematic diagram of the mud discharge system is as follows Figure 3 As shown, 10-the first filter tank water inlet, 11-the second filter tank water inlet, 12-the first filter tank, 13-the second filter tank, 17-the filtered water outlet, 19-the sewage suction port, 20-the back suction pump, and 21-the sewage suction pipe.

[0063] In the present invention, the sewage discharge component is used to discharge sludge, and after the sludge is discharged, it enters the magnetic loading flocculation system for further deep purification treatment.

[0064] In the present invention, the sewage outlet of the fiber rotary disk filtration system is connected to the water inlet of the magnetic loading flocculation system through a pipeline.

[0065] In the present invention, the industrialized fish and algae circulating water culture system includes a magnetic loading flocculation system; the magnetic loading flocculation system includes a mixing tank, a coagulation tank, a flocculation tank, a sedimentation tank, a magnetic powder recovery device and a sludge dewatering device connected in sequence.

[0066] In the present invention, the clarified water outlet of the sedimentation tank of the magnetic loading flocculation system is connected to the first filter tank and the second filter tank through pipelines, electric valves.

[0067] In the present invention, the sewage discharged by the back suction pump of the fiber rotary disk filtration system enters the mixing tank through a pipeline, and is sequentially treated through a coagulation tank, a flocculation tank and a sedimentation tank. The magnetic powder-containing flocs are precipitated in the sedimentation tank, the clarified water flows into the filter tank, a part of the magnetic powder-containing flocs is directly returned to the coagulation tank through a sludge pump, and a part enters the magnetic recovery device for magnetic powder recovery. The magnetic powder directly enters the coagulation tank. After the sludge is treated by a dehydration device, the solid matter can be used as organic fertilizer, and the effluent enters the sedimentation tank.

[0068] In the present invention, see the schematic diagram of the working principle of the magnetic loading flocculation system Figure 4 , where 22 - sewage inlet, 23 - mixing tank, 24 - coagulation tank, 25 - flocculation tank, 26 - sedimentation tank, 27 - purified water outlet, 28 - magnetic powder recovery device, 29 - sludge dehydration device, 30 - sludge pump.

[0069] In the present invention, stirring devices are preferably respectively arranged in the mixing tank, the coagulation tank and the flocculation tank.

[0070] In the present invention, the conveying pump for the magnetic powder-containing flocs is a screw pump, and its function is to convey the magnetic powder-containing flocs in the sedimentation tank to the coagulation tank or the magnetic powder recovery device.

[0071] In the present invention, the purified water outlet of the magnetic loading flocculation system is preferably connected to the inlet of the first filter tank and the inlet of the second filter tank of the fiber rotary disk filtration system through a pipeline.

[0072] In the present invention, the industrialized fish-algae circulating water aquaculture system preferably further includes a microalgae culture system, and the microalgae culture system preferably adopts a photofermentation culture system. The photofermentation culture system is a fermentation system with lighting facilities where light intensity, light quality and light cycle can be precisely regulated. This system retains the advantages of fermentation culture and overcomes the defect of low microalgae pigment content caused by dark culture, and can obtain microalgae with high pigment content and high biomass concentration on a large scale and with high efficiency. In the present invention, the photofermentation system is preferably purchased from Anhui Saide Qirui Biotechnology Co., Ltd.'s Bio 5000 full-automatic three-stage photofermentation system, which consists of three full-automatic stainless steel fermentation tanks of 100L, 1000L and 5000L and supporting lighting devices, feeding tanks, corresponding pipelines, valves, operation platforms, intelligent electrical control systems, etc. Operating parameters such as stirring speed, temperature, pH, DO, tank pressure, gas flow rate, light intensity, light quality and light cycle can all be automatically controlled.

[0073] In the present invention, the industrialized fish-algae recirculating aquaculture system preferably further includes a disinfection system; the disinfection system preferably includes an ozone and ultraviolet disinfection device. In the present invention, an ozone inlet is provided in the mixing tank of the magnetic loading flocculation system, and ozone is used to disinfect the sewage discharged from the fiber rotary disk filtration system. The amount of ozone introduced is 15-25 g / h, preferably 18-22 g / h, and more preferably 20 g / h. In the present invention, an ultraviolet sterilizer is provided at the clarified water outlet of the magnetic loading flocculation system. A number of ultraviolet lamps are provided inside the ultraviolet sterilizer. The power of the ultraviolet lamps is preferably 50-100 w, and more preferably 75 w; the brand of the ultraviolet lamps can be selected as Philips.

[0074] In the present invention, the industrialized fish-algae recirculating aquaculture system preferably further includes a water quality on-line monitoring system, and the water quality on-line monitoring system real-time on-line detects the dissolved oxygen, pH, water temperature, and residual chlorine in the fish pond.

[0075] The present invention also provides an industrialized fish-algae recirculating aquaculture method based on the industrialized fish-algae recirculating aquaculture system described in the above solution, including the following steps:

[0076] 1) Inject water into the fish pond body and add pre-domesticated microalgae seeds; the dosage of the microalgae seeds is 50-1000 mg / L of water body;

[0077] 2) Release fry and feed the fish pond every 3-5 h;

[0078] 3) During the aquaculture process, when the microalgae are at the end of the stable growth period and are about to enter the decline period, close the first fiber rotary disk filter and open the second fiber rotary disk filter, so that the microalgae cannot return to the fish pond again. The intercepted microalgae enter the magnetic loading flocculation system through the backwashing system for further treatment. Add a certain volume of pre-cultured highly active microalgae to make the algal density in the aquaculture water body 50-1000 mg / L, and harvest the fish after 150-200 d.

[0079] The present invention first injects water into the fish pond body and adds pre-domesticated microalgae seeds until the algal density in the aquaculture water body is 50-1000 mg / L.

[0080] In the present invention, the inlet water is preferably tap water, and the inlet water speed of the inlet water is preferably 60 m 2 / h; in the present invention, when the water surface height in the fish pond is 15-25 cm away from the top of the fish pond, the water inlet is completed; at 100 m 3Taking a fish pond body with a certain volume as an example, the time for completing water inlet is preferably 1 - 2 hours, more preferably 1.5 hours. After the water inlet is completed in the present invention, pre-cultured microalgae are added until the algae density in the aquaculture water body reaches 50 - 1000 mg / L, the algae density is preferably 100 - 500 mg / L, and more preferably 200 mg / L. After adding the microalgae is completed, the first fiber rotary disk filtration system is started. After running for 1 - 2 hours, fry are put into the fish pond. There is no special limitation on the type of the fry in the present invention, and any conventional aquaculture fish in the field can be used. In the specific implementation process of the present invention, the varieties of the fry include salmon, Yayu fish, rainbow trout, eastern star grouper, perch or mandarin fish. In the present invention, the stocking density of the fry is preferably 25 - 35 kg / m 3 , more preferably 28 - 32 kg / m 3 , and most preferably 30 kg / m 3 .

[0081] In the present invention, the microalgae can pass through the filter cloth in the first fiber rotary disk filter, but cannot pass through the filter cloth in the second fiber rotary disk filter; the microalgae species include one or more of chlorella, euglena, dunaliella, and Scenedesmus.

[0082] In the present invention, the microalgae are cultured using the photofermentation system; taking the photofermentation culture of chlorella as an example, 10 L of chlorella seeds are inoculated into a 100 L fermenter filled with sterilized culture medium. The light intensity continuously increases from 200 μmol / (m 2 .s) to 500 μmol / (m 2 ·s) according to the change of cell density. The pH of the culture medium is 6.0, the temperature is 30 °C, the stirring speed is 150 r / min, the aeration rate is 200 L / min, and the culture ends after 120 h. The feeding and feeding method during the culture process is: according to the growth of chlorella, several liters of 500 g / L glucose mother liquor are added once every 12 h to ensure that the glucose concentration in the culture medium is 20 - 25 g / L; 1 mol / L concentrated nitric acid is automatically added as the nitrogen source.

[0083] In the present invention, the microalgae species preferably include one or more of chlorella, euglena, dunaliella, and Scenedesmus.

[0084] After adding the pre-domesticated microalgae species, the present invention releases fry and feeds the fish pond every 3.5 - 4.5 hours.

[0085] In the present invention, when the fry are salmon, when the weight of more than 80% of single fish is 20 g, the initial water inflow rate is preferably 30 - 35 m 3 / h, more preferably 35 m 3 / h. When the weight of more than 80% of single fish is 100 g, the initial water inflow rate is preferably 35 - 40 m3 / h, more preferably 40 m 3 / h; when the weight of more than 80% of single fish is 200 - 500 g, the initial inlet water flow rate is preferably 45 - 50 m 3 / h, more preferably 50 m 3 / h; when the weight of more than 80% of single fish is 500 - 2000 g, the initial inlet water flow rate is preferably 50 - 60 m 3 / h, more preferably 60 m 3 / h, when the weight of more than 80% of single fish is 2000 - 3500 g, the initial inlet water flow rate is preferably 60 - 70 m 3 / h, more preferably 70 m 3 / h. When the fry is Yayu, the initial inlet water flow rate is preferably controlled at 28 - 32 m 3 / h, more preferably 30 m 3 / h, the initial outlet water flow rate is preferably 28 - 32 m 3 / h, 30 m 3 / h. In the present invention, with the growth of the cultured fry, different water inlet and outlet flow rates are set according to the density of the cultured fish body. When the culture density in the water body is greater than or equal to 30 kg / m 3 , and less than 60 kg / m 3 , the water inflow and outflow are respectively set to 35 - 45 m 3 / h, preferably 38 - 42 m 3 / h, more preferably 40 m 3 / h; when the culture density in the water body is greater than or equal to 60 kg / m 3 , and less than 100 kg / m 3 , the water inflow and outflow are respectively set to 55 - 65 m 3 / h, preferably 58 - 62 m 3 / h, more preferably 60 m 3 / h; when the culture density in the water body is greater than or equal to 100 kg / m 3 , and less than 200 kg / m 3 , the water inflow and outflow are respectively set to 70 - 90 m 3 / h, preferably 75 - 85 m 3 / h, more preferably 80 m 3 / h.

[0086] In the present invention, when the culture density in the water body is greater than or equal to 30 kg / m 3 , and less than 60 kg / m 3 , the water inflow and outflow are respectively set to 35 - 45 m 3 / h; when the culture density in the water body is greater than or equal to 60 kg / m 3, and less than 100 kg / m 3 When it is, the water inflow and water outflow are respectively set to 55 - 65 m 3 / h; when the aquaculture density in the water body is greater than or equal to 100 kg / m 3 , and less than 200 kg / m 3 When it is, the water inflow and water outflow are set to 70 - 90 m 3 / h.

[0087] In the present invention, during the aquaculture process, the dissolved oxygen content in the aquaculture water body is 5 - 12 mg / L.

[0088] In the present invention, it is preferable to feed the fish pond with feed every 4 h. In the present invention, when the weight of a single fish is 30 - 50 g, the feeding amount of the feed is preferably 2.5% - 3% of the total weight of the fish in the aquaculture water body; the dosage of the algal species is preferably 800 - 1200 L / 100 m 3 Water body; when the weight of a single fish is 200 - 500 g, the feeding amount of the feed is preferably 2% - 2.5% of the total weight of the fish in the aquaculture water body.

[0089] During the aquaculture process, when the microalgae are at the end of the stable growth phase and about to enter the decline phase, close the first fiber rotary disk filter and open the second fiber rotary disk filter, so that the microalgae cannot return to the fish pond again. The intercepted microalgae enter the magnetic loading flocculation system through the backwashing system for further treatment. Add a certain volume of pre-cultured highly active microalgae to make the algal density in the aquaculture water body 50 - 1000 mg / L, and harvest the fish after 150 - 200 d.

[0090] In the present invention, the addition of microalgae has multiple effects. On the one hand, microalgae can effectively remove soluble pollutants such as nitrogen and phosphorus in the water body. After adding microalgae, microalgae can use soluble pollutants such as nitrogen and phosphorus in the water body as nutrients to achieve the growth and reproduction of microalgae in the water body; on the other hand, the growth and reproduction of microalgae can release oxygen, and the released oxygen can be utilized by the fish in the water body, thereby reducing the demand for artificial oxygenation. Further, Chlorella also has an inhibitory effect, which can inhibit the growth of harmful bacteria in the water body, maintain the water environment, and prevent the fish in the water body from being infected by harmful bacteria; in addition, the microalgae added to the water body can also be used as fish feed for fish to eat; at the same time, the polysaccharides produced on the surface of microalgae can agglomerate and wrap nearby insoluble particulate pollutants, which can increase the particle size and further promote the sedimentation of particulate pollutants, facilitating the rapid separation of particulate pollutants.

[0091] In the present invention, during the aquaculture process, oxygen is added to the fish-algae aquaculture system through an oxygenation cone. The present invention determines whether oxygenation is required according to the concentration of dissolved oxygen; the dissolved oxygen in the fish-algae aquaculture system is maintained above 7.0 mg / L; when the dissolved oxygen in the fish farming system is lower than 7.0 mg / L, oxygenation is carried out.

[0092] The present invention harvests after 150 - 200 days of fish farming. In the present invention, when the fish is rainbow trout, the weight of the fry stocked is 4.5 - 5.5 g, preferably harvested after 170 - 190 days of farming, and the weight of the harvested rainbow trout is 450 - 550 g. When the fish is salmon, the weight of the fry stocked is 4.5 - 5.5 g, and the weight of the harvested salmon is 2000 - 3600 g.

[0093] In the industrialized fish - algae recirculating aquaculture using the aquaculture system of the present invention, during the aquaculture process, micro - algae are regularly added to the fish - algae aquaculture system. The micro - algae convert nutrients such as CO2, nitrogen, and phosphorus in the water into algal cells as their own substances, purify the water quality in the fish pond, and use the fiber rotary disk filtration system and the magnetic loading flocculation system to quickly and fully remove suspended substances, macromolecular proteins, algae, bacteria, and viruses in the aquaculture water body, realizing the recycling of aquaculture sewage with zero sewage discharge; it can truly achieve high - density, high - stability, and low - energy - consumption recirculating aquaculture.

[0094] The technical solutions provided by the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0095] Example 1

[0096] The system adopted is an industrialized fish - algae recirculating aquaculture system. The industrialized fish - algae recirculating aquaculture system includes a fish - farming system, an algae - farming system, and a water - treatment system. The fish - farming system is built with polypropylene plates into a fish pond with a water volume of 100 m 3 The aquaculture output can reach 15 tons, and the aquaculture density can reach 150 kg / m 3 , and the single - species fish can reach more than 3 kg. Currently, the fish species in the experiment is salmon, and the single weight can reach 3.6 kg / tail. For normal recirculating aquaculture of 100 m 3 of water body, the energy consumption is 20 kw / h. For the industrialized fish - algae recirculating aquaculture system of the present invention, the energy consumption for 100 m 3 of water body is 4 kw / h. The detailed data is shown in Table 1.

[0097] Table 1 Comparison between the fish - algae recirculating aquaculture system and the conventional recirculating aquaculture system in this example

[0098]

[0099]

[0100] The above - mentioned are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as within the protection scope of the present invention.

Claims

1. A factory fish-algae recirculating aquaculture method based on a factory fish-algae recirculating aquaculture system, characterized in that, The industrialized fish-algae recirculating aquaculture system includes a fish-algae aquaculture system, a fiber rotary disk filtration system, and a magnetic loading flocculation system; The fish-algae aquaculture system includes a fishpond body, a water inlet system, and a water outlet system; The fiber rotary disk filtration system includes a first fiber rotary disk filtration system and a second fiber rotary disk filtration system; the first fiber rotary disk filtration system is located in a first filtration pond; The second fiber rotary disk filtration system is located in a second filtration pond; the first fiber rotary disk filtration system and the second fiber rotary disk filtration system respectively include fiber rotary disk filters, backwashing systems, sludge discharging systems, and supporting electrical control systems; the filtration fluxes of the first fiber rotary disk filtration system and the second fiber rotary disk filtration system for the same aquaculture sewage are equal; the filtration pore diameter of the filter cloth in the first fiber rotary disk filter is 15 - 30 μm; the filtration pore diameter of the filter cloth in the second fiber rotary disk filter is 1 - 5 μm; a filtered water collection tank is arranged between the first filtration pond and the second filtration pond; the filtered water collection tank is provided with a filtered water outlet; the first fiber rotary disk filtration system and the second fiber rotary disk filtration system share the filtered water collection tank, the filtered water outlet, a backsuction pump, and a sewage discharge port; The water outlet system of the fish-algae aquaculture system is communicated with the first filtration pond and the second filtration pond respectively through pipelines; The filtered water outlet of the fiber rotary disk filtration system is communicated with the water inlet system of the fish-algae aquaculture system through a pipeline; The sewage discharge port of the fiber rotary disk filtration system is communicated with the water inlet of the magnetic loading flocculation system through a pipeline; The magnetic loading flocculation system includes a mixing tank, a coagulation tank, a flocculation tank, a sedimentation tank, a magnetic powder recovery device, and a sludge dewatering device; The sedimentation tank of the magnetic loading flocculation system is provided with a clarified water outlet; the clarified water outlet is communicated with the first filtration pond and the second filtration pond respectively through pipelines; The industrialized fish-algae recirculating aquaculture method includes the following steps: 1) Inject water into the fishpond body and add pre-cultured highly active microalgae until the algae density in the aquaculture water body reaches 50 - 1000 mg / L; 2) Release fry and feed the fishpond every 3 - 5 h; 3) During the aquaculture process, during normal water circulation, turn on the first fiber rotary disk filter with a filtration pore diameter of 15 - 30 μm. The microalgae can return to the fishpond through the first fiber rotary disk filter and be reused; larger suspended matters such as fish feces and residual baits either directly sink to the bottom of the filtration pond or are intercepted by the filter cloth of the first fiber rotary disk filter, and finally enter the magnetic loading flocculation system through the sludge discharging system or the backwashing system for further in-depth purification treatment; when the microalgae are at the end of the stable growth period and are about to enter the decline period, it is necessary to remove the microalgae in the aquaculture water body. Turn off the first fiber rotary disk filter and turn on the second fiber rotary disk filter with a filtration pore diameter of 1 - 5 μm for interception, so that the microalgae cannot return to the fishpond and enter the magnetic loading flocculation system through the backwashing system for further purification treatment. Add a certain volume of pre-cultured highly active microalgae to make the algae density in the aquaculture water body reach 50 - 1000 mg / L, and harvest the fish after 150 - 200 d.

2. The industrialized fish-algae circulating water aquaculture method according to claim 1, wherein, The water inlet system includes a number of water inlet pipes, which are distributed on the side wall of the fish pond body, and the fish pond water inlets are arranged at equal intervals in the tangential direction.

3. The industrialized fish-algae recirculating aquaculture method according to claim 1, characterized in that, The fiber rotary disk filter includes a central drum and a rotary disk; the rotary disk is fixed around the central drum and is communicated with the central drum through a communication hole; filter cloths are installed on both sides of the rotary disk; the first fiber rotary disk filtration system and the second fiber rotary disk filtration system have equal filtration fluxes for the same aquaculture sewage.

4. The industrialized fish-algae recirculating aquaculture method according to claim 1, wherein, The sludge discharge system includes sludge discharge pipes respectively arranged at the bottoms of the first filtration tank and the second filtration tank, and the sludge discharge pipes are communicated with a reverse suction pump through pipelines; electric valves are respectively arranged on the sludge discharge pipes in the first filtration tank and the second filtration tank.

5. The industrialized fish-algae circulating water aquaculture method according to claim 1, characterized in that, The magnetic loading flocculation system includes a mixing tank, a coagulation tank, a flocculation tank, a sedimentation tank, a magnetic powder recovery device and a sludge dewatering device which are connected in sequence.

6. The industrialized fish-algae recirculating aquaculture method according to claim 1, characterized in that The breeding density is 25 - 35 kg / m 3 .

7. The industrialized fish-algae circulating water aquaculture method according to claim 1, characterized in that When the aquaculture density in the water body is greater than or equal to 30 kg / m 3 , and less than 60 kg / m 3 , the water inflow and outflow are set to 35 - 45 m 3 / h respectively; when the aquaculture density in the water body is greater than or equal to 60 kg / m 3 , and less than 100 kg / m 3 , the water inflow and outflow are set to 55 - 65 m 3 / h respectively; When the aquaculture density in the water body is greater than or equal to 100 kg / m 3 , and less than 200 kg / m 3 , the water inflow and outflow are set to 70 - 90 m 3 / h.

8. The industrialized fish-algae circulating water aquaculture method according to claim 1, characterized in that, During the aquaculture process, the dissolved oxygen content in the aquaculture water body is 5 - 12 mg / L.

9. The industrialized fish-algae circulating water aquaculture method according to claim 1, characterized in that, The microalgae can pass through the filter cloth in the first fiber rotary disk filter but cannot pass through the filter cloth in the second fiber rotary disk filter; the microalgae include one or more of Chlorella vulgaris, Nannochloropsis oculata, Dunaliella salina, and Chlamydomonas reinhardtii.

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