Integrated water treatment filter for recirculating aquaculture system and filtering method

Abstract

The invention relates to an integrated water treatment filter for a recirculating aquaculture system and a filtering method, and belongs to the field of water treatment. The device comprises a biological filtration unit and a physical filtration unit, and is structurally characterized in that the physical filtration unit is located in the biological filtration unit, and the physical filtration unit is located at the upper end of the biological filtration unit; the physical filtering unit is located in the biological filtering unit, and the physical filtering unit is located at the upper end of the biological filtering unit; the physical filtering unit comprises a bead intercepting net, a filtering barrel, a back washing spraying device and floating bead filler, the bead intercepting net is arranged at the top of the filtering barrel, the back washing spraying device is located in the filtering barrel, the floating bead filler is arranged in the filtering barrel, and the back washing spraying device is located in the filtering barrel. The biological filtration unit comprises a barrel body, an aeration device and a high-specific-surface-area filler, the filtration barrel, the aeration device and the high-specific-surface-area filler are all located in the barrel body, and the aeration device is located at the bottom of the barrel body.

Description

TECHNICAL FIELD

[0001] The present application relates to an integrated water treatment filter for a recirculating aquaculture system and a filtering method, and belongs to the field of water treatment. BACKGROUND

[0002] In a recirculating aquaculture system, efficient removal of water pollutants (such as suspended particles, NH4⁺, NO2⁻) is the core to maintain a stable water environment and ensure the health of the cultured organisms. In the current conventional aquaculture system, the suspended particles in the water are mainly removed by using a settler, a microfilter and a protein separator as the core physical filtration device, and these devices are usually integrated in the system in a combined form. However, these conventional commercial solutions have two major problems: first, there is a particle size processing blind area: suspended particles with a particle size of 30-70 μm are difficult to be effectively intercepted, resulting in their continuous accumulation in the recirculating water, which eventually leads to instability of the water environment and affects the growth of the cultured organisms.

[0003] Second, the system has low integration and high energy consumption: the traditional "vertical flow settler + microfilter + protein separator" scheme requires multiple independent units, which occupies a large area and has high land cost. At the same time, except for the settler which does not require power, the rotating filter screen of the microfilter and the aeration system of the protein separator all require a large amount of energy consumption.

[0004] As for the dissolved pollutants such as NH4⁺ and NO2⁻, a moving bed biological reactor (MBBR) is usually used for biological denitrification, and the core of its treatment efficiency lies in the filler. The higher the specific surface area of the filler, the more nitrifying microorganisms can be attached, and theoretically the stronger the treatment capacity. However, high specific surface area fillers (such as membrane fillers) are easily clogged by particles in the water. Once clogged, not only will the pollutant removal efficiency be greatly reduced, but the clogged area may also form an anaerobic environment, producing toxic fermentation products that directly threaten the survival of aquatic products. Therefore, to take advantage of high-performance fillers, more stringent requirements are needed for the physical filtration link at the front end. SUMMARY

[0005] The present application aims to overcome the above-mentioned deficiencies in the prior art and provide an integrated water treatment filter for a recirculating aquaculture system and a filtering method with a reasonable structure design.

[0006] The technical solution adopted by this invention to solve the above problems is as follows: An integrated water treatment filter for recirculating aquaculture systems includes a biological filtration unit and a physical filtration unit. Its structural features are as follows: the physical filtration unit is located within the biological filtration unit and at its upper end; the physical filtration unit includes a beaded interceptor, a filter barrel, a backwash spray device, and floating beaded packing material. The beaded interceptor is located at the top of the filter barrel, the backwash spray device is located inside the filter barrel, and floating beaded packing material is installed inside the filter barrel. The biological filtration unit includes a barrel body, an aeration device, and high specific surface area packing material. The filter barrel, aeration device, and high specific surface area packing material are all located inside the barrel body, and the aeration device is located at the bottom of the barrel body.

[0007] Furthermore, the side wall of the filter bucket is provided with an inlet / outlet, the inlet / outlet is connected to the first interface of the tee, the second interface of the tee is connected to the inlet valve, and the third interface of the tee is connected to the drain valve.

[0008] Furthermore, the backwash spray device is connected to the backwash valve.

[0009] Furthermore, an air inlet is provided at the bottom of the barrel, and the air inlet is connected to an aeration device.

[0010] Furthermore, a drain outlet is provided at the bottom of the barrel.

[0011] Furthermore, the backwashing spray device is equipped with multiple nozzles in different directions.

[0012] Furthermore, the aeration device is an aeration component at the bottom of the tank. The aeration component is at least one of a microporous aeration disc, a tubular aerator, or a swirling aerator, and is installed in a uniformly distributed, zoned, or coordinated manner with the filter media layer structure. It is used to oxygenate the water and promote water circulation and pollutant mixing and degradation.

[0013] Furthermore, another technical objective of the present invention is to provide a treatment method for an integrated water treatment filter used in a recirculating aquaculture system.

[0014] The above-mentioned technical objective of the present invention is achieved through the following technical solution.

[0015] A treatment method for an integrated water treatment filter used in a recirculating aquaculture system is characterized in that the treatment method involves first performing physical filtration through a physical filtration unit, and then performing biological filtration through a biological filtration unit. During physical filtration: Open the inlet valve and close the drain valve. The water to be treated enters the filter tank from the inlet / outlet. When the water flows through the floating bead packing, the suspended solids are filtered through the tiny pores between the floating beads. Because the suspended particles in the water are larger than the pore size, or through inertial collision and surface adsorption, they are trapped on the surface and in the pores of the floating beads packing, thus completing efficient physical purification and providing low suspended solids inlet water for subsequent biological treatment. When the suspended solids trapped by the floating bead filter layer reach the set threshold, the inlet valve is closed and the backwash valve is opened, the filter is switched to the backwash state, and the backwash water can wash the floating bead filter through the nozzle of the backwash spray device to ensure that the suspended solids trapped on the surface of the floating bead filter are completely removed. The wastewater containing suspended solids generated during rinsing settles naturally in the filter tank. Once the suspended solids have accumulated at the bottom, the drain valve is opened to discharge the wastewater from the inlet / outlet into the filter tank. During biological filtration: After physical purification by the physical filtration unit, the water flows into the biological filtration unit by gravity from the top of the beaded interceptor net through overflow, without the need for additional power. Air is introduced into the aeration device through the air inlet, so that the aeration device provides sufficient dissolved oxygen for the biofilm attached to the high specific surface area packing. The stirring action generated by aeration promotes the uniform fluidization of the high specific surface area packing in the water, so that the microbial film on the surface of the high specific surface area packing is in full contact with the water, which greatly improves the mass transfer efficiency. Finally, the water purified by the biological filtration unit is discharged through the drain at the bottom of the tank.

[0016] Compared with existing technologies, the present invention has the following advantages: The physical filtration unit used in this integrated high-efficiency water treatment device can stably remove the critical particle size range of 30-70μm that cannot be covered by traditional processes, as well as the finer suspended solids of 15-30μm. Depending on the beads, the maximum removal rate of suspended particles can generally reach more than 90%. This filtration efficiency can directly reduce pollutants in circulating water, such as suspended solids and COD.

[0017] Using the physical filtration unit as a pretreatment unit before the biological filtration unit can control the concentration of suspended solids (SS) in the water entering the tank to below 10 mg / L, cutting off the path for 30-70 μm particles to enter the subsequent process. This ensures that the microporous structure of the packing material is not blocked, guaranteeing sufficient attachment sites for nitrifying bacteria (such as Nitrosomonas and Nitrobacterium) and unrestricted activity, thus ensuring long-term stable removal rates of ammonia nitrogen and nitrite. This effectively avoids the problem of nitrification efficiency decaying over time due to packing blockage in traditional processes.

[0018] The physical filtration unit has a conical bottom, which allows the aerated packing material to spread outwards from the center. Water overflowing from the physical filtration unit further intensifies the tendency of the packing material to flow towards the bottom. This results in better fluidization of the packing material within the biological filtration unit, allowing for a higher fill ratio. Furthermore, the membrane packing material has a surface area several times larger than conventional high-density polyethylene suspended packing material (such as K5 packing), giving it a higher processing capacity and further increasing the processing load of the integrated unit.

[0019] This technology organically combines physical filtration with biological filtration (moving bed biofilm reactor) to save space. The physical filtration unit can quickly remove suspended particulate matter and effectively reduce the risk of clogging by subsequent high specific surface area packing and the treatment load of the biological filtration system. The biological filtration unit can degrade soluble pollutants such as ammonia nitrogen and nitrite, thereby preventing the accumulation of pollutants in the aquaculture system and ultimately achieving the normal operation of the recirculating water system and high-density aquaculture. Attached Figure Description

[0020] Fig. 1 This is a schematic diagram of the structure of the integrated water treatment filter according to an embodiment of the present invention.

[0021] Fig. 2 This is a schematic diagram of the backwashing spray device according to an embodiment of the present invention.

[0022] Fig. 3 This is a diagram illustrating the effect of the physical filtration unit in an embodiment of the present invention on the removal of suspended solids.

[0023] In the diagram: biological filtration unit, physical filtration unit, 1. Barrel body; 2. Beaded interception net; 3. Filter barrel; 4. Backwash spray device; 5. Aeration device; 6. Inlet / outlet; 7. Inlet valve; 8. Drain valve; 9. Air inlet; 10. Drain outlet; 11. Spray head; 12. High specific surface area packing A, floating bead packing B. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are explanations of the present invention, but the present invention is not limited to the following embodiments.

[0025] Example

[0026] See Figs. 1 to 3As shown in the accompanying drawings, the structures, proportions, sizes, etc., depicted are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness or purpose of the invention, should still fall within the scope of the disclosed technical content. Furthermore, the use of terms such as "upper," "lower," "left," "right," "middle," and "one" in this specification is merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0027] The integrated water treatment filter for the recirculating aquaculture system in this embodiment includes a biological filtration unit and a physical filtration unit. The physical filtration unit is located inside the biological filtration unit and at the top of the biological filtration unit.

[0028] The physical filtration unit in this embodiment includes a bead interception net 2, a filter barrel 3, a backwash spray device 4, and floating bead packing B. The bead interception net 2 is located on the top of the filter barrel 3, the backwash spray device 4 is located inside the filter barrel 3, and the floating bead packing B is installed inside the filter barrel 3. The floating bead packing B is intercepted by the bead interception net 2 to prevent it from flowing out of the physical filtration unit.

[0029] Floating bead packing material B consists of hollow or solid plastic balls / beads with smooth or slightly textured surfaces, ranging in diameter from 1 mm to 5 mm, and a density of less than 1.0 g / cm³. When the water to be treated flows through this packing layer from bottom to top or horizontally, the packing effectively captures and retains suspended particles, undigested food residues, and larger organic debris in the water through direct collision, inertial interception, and surface adsorption, thereby achieving physical filtration.

[0030] The biological filtration unit in this embodiment includes a barrel 1, an aeration device 5, and a high specific surface area packing A. The filter barrel 3, the aeration device 5, and the high specific surface area packing A are all located inside the barrel 1. The aeration device 5 is located at the bottom of the barrel 1. The aeration device 5 is an aeration component at the bottom of the barrel 1. The aeration component is at least one of a microporous aeration disc, a tubular aerator, or a swirling aerator, and is installed in a uniformly distributed, zoned, or coordinated manner with the filter media layer structure. It is used to oxygenate the water and promote water circulation and the mixing and degradation of pollutants.

[0031] High specific surface area filler A has a specific surface area greater than or equal to 5000 m². 2 / m 3Biofilm carrier packing materials, whose forms include, but are not limited to, porous spheres, columns, hollow rings or regular / irregular porous blocks.

[0032] In this embodiment, the filter bucket 3 has an inlet / outlet 6 on its side wall. The inlet / outlet 6 is connected to the first interface of the tee, the second interface of the tee is connected to the inlet valve 7, and the third interface of the tee is connected to the drain valve 8. The backwash spray device 4 is connected to the backwash valve 9. The bottom of the bucket body 1 has an air inlet 10 and a drain outlet 11. The air inlet 10 is connected to the aeration device 5. The backwash spray device 4 has multiple nozzles 12 in different directions.

[0033] The integrated water treatment filter for the recirculating aquaculture system in this embodiment uses a physical filtration unit for physical filtration and a biological filtration unit for biological filtration. During physical filtration: Open the inlet valve 7 and close the drain valve 8. The water to be treated enters the filter tank 3 from the inlet / outlet 6. When the water flows through the floating bead packing B, the suspended solids are filtered through the tiny pores between the floating bead packing B. Because the suspended particles in the water are larger than the pore size, or through inertial collision and surface adsorption, they are trapped on the surface and in the pores of the floating bead packing B, thereby completing efficient physical purification and providing low suspended solids inlet water for subsequent biological treatment. When the suspended solids trapped by the floating bead packing B filter layer reach the set threshold, the inlet valve 7 is closed and the backwash valve 9 is opened. The filter is switched to the backwash state. The backwash water can wash the floating bead packing B through the nozzle 12 of the backwash spray device 4 to ensure that the suspended solids trapped on the surface of the floating bead packing B are completely removed. The wastewater containing suspended solids generated during rinsing settles naturally in the filter tank 3. After the suspended solids accumulate at the bottom, the drain valve 8 is opened to discharge the wastewater from the inlet / outlet 6 into the filter tank 3. During biological filtration: After physical purification by the physical filtration unit, the water flows into the biological filtration unit by gravity from the top of the beaded interceptor 2 through overflow, without the need for additional power. Air is introduced into the aeration device 5 through the air inlet 10 so that the aeration device 5 provides sufficient dissolved oxygen for the biofilm attached to the high specific surface area packing A. The agitation generated by aeration also promotes the uniform fluidization of the high specific surface area packing A in the water, so that the microbial film on the surface of the high specific surface area packing A is in full contact with the water, which greatly improves the mass transfer efficiency. Finally, the water purified by the biological filtration unit is discharged through the drain outlet 11 at the bottom of the tank 1.

[0034] The effect of physical filtration unit in removing suspended solids is shown in the image. Fig. 3 As shown: The figure shows that when the influent suspended solids concentration is 2732 mg / L, the effluent suspended solids concentration is 1268 mg / L, with a removal rate of 53.59%; when the influent suspended solids concentration is 510 mg / L, the effluent suspended solids concentration is 168 mg / L, with a removal rate of 67.06%; when the influent suspended solids concentration is 294 mg / L, the effluent suspended solids concentration is 72 mg / L, with a removal rate of 75.51%; when the influent suspended solids concentration further decreases to below 50 mg / L, the effluent suspended solids concentration is significantly less than 5 mg / L, and the removal rate is greater than 90%.

[0035] In recirculating aquaculture systems, the concentration of suspended solids in the discharged water is greatly influenced by factors such as the fish species, growth stage, and feed dosage. The concentration is generally 15-60 mg / L, and this range widens, especially in the period following feed addition. Therefore, physical filtration significantly reduces suspended solids in the aquaculture water, ensuring a healthy growth environment for the cultured organisms. It also prevents clogging of the high surface area packing material in the biological filtration unit, providing sufficient growth sites for nitrifying microorganisms. Even if the suspended solids concentration in the aquaculture water rises sharply due to operational malfunctions, the physical filtration unit still achieves ideal removal efficiency even with high suspended solids in the influent, ensuring the system can quickly return to normal operation, thus guaranteeing the normal growth of the cultured organisms and the proper functioning of the biological filtration unit.

[0036] Furthermore, it should be noted that the specific embodiments described in this specification may differ in the shape and name of their components, etc. The above description is merely illustrative of the structure of the present invention. All equivalent or simple variations made based on the structure, features, and principles described in this invention are included within the scope of protection of this invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to substitute them, as long as they do not depart from the structure of the invention or exceed the scope defined by the claims, all of which should fall within the scope of protection of this invention.

Claims

1. An integrated water treatment filter for a recirculating aquaculture system, comprising a biological filtration unit and a physical filtration unit, characterized in that: The physical filtration unit is located inside the biological filtration unit and at the top of the biological filtration unit; the physical filtration unit includes a beaded interceptor (2), a filter barrel (3), a backwash spray device (4), and floating bead packing (B). The beaded interceptor (2) is located at the top of the filter barrel (3), the backwash spray device (4) is located inside the filter barrel (3), and the filter barrel (3) is equipped with floating bead packing (B). The biological filtration unit includes a barrel body (1), an aeration device (5), and a high-pressure aeration unit. The filter barrel (3), aeration device (5) and high specific surface area filler (A) are all located inside the barrel body (1). The aeration device (5) is located at the bottom of the barrel body (1). The side wall of the filter barrel (3) is provided with an inlet / outlet (6). The inlet / outlet (6) is connected to the first interface of the tee. The second interface of the tee is connected to the inlet valve (7). The third interface of the tee is connected to the drain valve (8). The backwash spray device (4) is provided with multiple nozzles (12) in different directions.

2. The integrated water treatment filter for a recirculating aquaculture system according to claim 1, characterized in that: The backwash spray device (4) is connected to the backwash valve (9).

3. The integrated water treatment filter for a recirculating aquaculture system according to claim 1, characterized in that: The bottom of the barrel (1) is provided with an air inlet (10), which is connected to the aeration device (5).

4. The integrated water treatment filter for a recirculating aquaculture system according to claim 1, characterized in that: The bottom of the barrel (1) is provided with a drain outlet (11).

5. The integrated water treatment filter for a recirculating aquaculture system according to claim 1, characterized in that: The aeration device (5) is an aeration component at the bottom of the barrel (1), and the aeration component is at least one of a microporous aeration disc, a tubular aerator, or a vortex aerator.

6. A method for treating water using an integrated water treatment filter for a recirculating aquaculture system as described in any one of claims 1-5, characterized in that: The processing method involves first performing physical filtration through a physical filtration unit, and then performing biological filtration through a biological filtration unit. When performing physical filtration: open the inlet valve (7) and close the drain valve (8). The water to be treated enters the filter bucket (3) from the inlet / outlet (6). When the water to be treated flows through the floating bead packing (B), the suspended matter is filtered through the tiny pores between the floating bead packing (B). The suspended particles in the water are trapped on the surface and in the pores of the floating bead packing (B) because the particle size is larger than the pore size, or through inertial collision and surface adsorption. This completes the efficient physical purification and provides low suspended matter inlet water for subsequent biochemical treatment. When the suspended matter trapped by the floating bead packing (B) filter layer reaches the set threshold, the inlet valve (7) is closed and the backwash valve (9) is opened. The filter is switched to the backwash state. The backwash water can wash the floating bead packing (B) through the nozzle (12) of the backwash spray device (4) to ensure that the suspended matter trapped on the surface of the floating bead packing (B) is completely removed. The wastewater containing suspended solids generated during rinsing settles naturally in the filter tank (3). After the suspended solids accumulate at the bottom, the drain valve (8) is opened to discharge the wastewater from the inlet / outlet (6) into the filter tank (3). During biological filtration: After physical purification by the physical filtration unit, the water flows into the biological filtration unit by gravity from the top of the beaded interceptor net (2) without the need for additional power. Air is introduced into the aeration device (5) through the air inlet (10) so that the aeration device (5) provides sufficient dissolved oxygen for the biofilm attached to the high specific surface area packing (A). The stirring action generated by aeration promotes the high specific surface area packing (A) to be uniformly fluidized in the water, so that the microbial film on the surface of the high specific surface area packing (A) is in full contact with the water, greatly improving the mass transfer efficiency. Finally, the water purified by the biological filtration unit is discharged through the drain outlet (11) at the bottom of the barrel (1).

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