Denitrification bioreactor, high dissolved oxygen recirculating water treatment system

Abstract

The utility model provides a kind of denitrification bioreactor, high dissolved oxygen circulating water treatment system, it is related to the technical field of high dissolved oxygen circulating water treatment, this denitrification bioreactor includes membrane degassing contactor, membrane deoxygenation bioreactor, membrane oxygen transfer bioreactor and membrane oxygenation contactor in turn according to water treatment order;Membrane degassing contactor is used to remove carbon dioxide in water, adjusts the pH of water body;Membrane deoxygenation bioreactor is used to remove oxygen in water, provides suitable reaction condition for denitrification process;Membrane oxygen transfer bioreactor is used to form aerobic-anoxic biofilm layer to carry out simultaneous nitrification and denitrification, remove ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in water.The utility model solves the technical problem that existing technology exists higher energy consumption and poor denitrification effect when circulating water aquaculture is water treated, reaches the technical effect of low energy consumption, controllable biofilm method denitrification.

Description

Technical Field

[0001] This utility model relates to the technical field of high dissolved oxygen circulating water treatment, and in particular to a denitrification bioreactor and a high dissolved oxygen circulating water treatment system. Background Technology

[0002] Recirculating aquaculture systems are a new type of aquaculture model that treats and recycles wastewater generated in aquaculture ponds through a series of water treatment units. The levels of ammonia nitrogen, nitrite, nitrate, and carbon dioxide in the water will continue to accumulate and need to be removed through physical or biological filtration. This provides a stable, reliable, comfortable, and high-quality living environment for the farmed organisms and creates favorable conditions for high-density aquaculture.

[0003] To ensure the activity of cultured organisms, the dissolved oxygen in the circulating water is generally above 5 mg / L, and the circulation volume is large. The water treatment heating time (HRT) is only 0.5 h to 2 h, maintaining a consistently high dissolved oxygen level. This makes it difficult to cultivate anaerobic denitrifying bacteria during biological filtration, leading to a continuous accumulation of nitrates in the system, which can only be diluted by increasing the water exchange rate. Simultaneously, due to the respiration of the cultured organisms, the carbon dioxide in the water continuously increases, often requiring neutralization through a decarbonation tower or the addition of sodium hydroxide. This leads to increased salt content, further affecting the water exchange rate.

[0004] Because the water circulation speed of the system is very fast, it is impossible to cultivate activated sludge in the water treatment system. Usually, FBBR or MBBR is used as a carrier for biofilm formation, which has high energy consumption and poor denitrification effect.

[0005] In view of the above, this utility model is hereby proposed. Utility Model Content

[0006] One of the objectives of this invention is to provide a denitrification bioreactor that solves the technical problems of high energy consumption and poor denitrification effect in water treatment during recirculating aquaculture in the prior art, and achieves the technical effect of low energy consumption and controllable biofilm denitrification.

[0007] The second objective of this invention is to provide a high dissolved oxygen circulating water treatment system that can effectively remove nitrogen from high dissolved oxygen circulating water with low energy consumption.

[0008] The present invention provides a denitrification bioreactor, which, in the order of water treatment, includes a membrane degassing contactor, a membrane deoxygenation bioreactor, a membrane oxygen transfer bioreactor, and a membrane oxygenation contactor. The membrane degassing contactor is used to remove carbon dioxide from water and adjust the pH of the water. The membrane deoxygenation bioreactor is used to remove oxygen from the water, providing suitable reaction conditions for the denitrification process; The membrane oxygen transfer bioreactor is used to form an aerobic-anoxic biofilm layer to carry out simultaneous nitrification and denitrification reactions to remove ammonia nitrogen, nitrite nitrogen and nitrate nitrogen from the water; The membrane oxygenation contactor is used to transfer oxygen into the water.

[0009] Furthermore, the membrane filaments used in the membrane degassing contactor include hollow fiber hydrophobic membranes.

[0010] Furthermore, the surface pore size of the hollow fiber hydrophobic membrane is less than 20 nm; The diameter of the hollow fiber hydrophobic membrane is less than 0.6 mm.

[0011] Furthermore, the membrane deoxygenation bioreactor includes a membrane tank, a deoxygenation membrane assembly immersed in the membrane tank, and a vacuum pump that is sealed and connected to the deoxygenation membrane assembly; The vacuum pump is connected to the membrane degassing contactor and the membrane deoxygenation bioreactor via a buffer tank.

[0012] Furthermore, the deoxygenation membrane assembly includes a hollow fiber membrane filament woven mesh.

[0013] Furthermore, the hollow fiber membrane filaments include hydrophobic microporous membranes; The pore size of the hollow fiber membrane filament is less than 20 nm; The spacing between the membrane filaments in the hollow fiber membrane woven mesh is 0.1mm to 1mm, and the spacing between the woven ropes is 1mm to 20mm.

[0014] Furthermore, the membrane degassing contactor, the membrane deoxygenation bioreactor, and the membrane oxygen transfer bioreactor are also independently equipped with intermittent aeration devices for intermittent aeration to flush the membrane surface.

[0015] Furthermore, the inner side of the membrane in the membrane oxygen transfer bioreactor is connected to an air pump; The membrane oxygen transfer bioreactor includes a non-porous oxygen transfer membrane woven mesh.

[0016] Furthermore, the membrane filaments used in the membrane oxygenation contactor include hollow fiber hydrophobic membranes; The surface pore size of the hollow fiber hydrophobic membrane is less than 20 nm; The diameter of the hollow fiber hydrophobic membrane is less than 0.6 mm; The membrane fibers of the membrane oxygenation contactor are arranged laterally in the outlet pipe of the membrane tank; The inner side of the membrane fiber of the membrane oxygenation contactor is connected to the pressurized pure oxygen tank.

[0017] The present invention provides a high dissolved oxygen circulating water treatment system, including any of the above-mentioned denitrification bioreactors.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The denitrification bioreactor provided by this utility model simultaneously removes carbon dioxide from circulating water and adjusts the pH of the circulating water through a membrane degassing contactor. The membrane deoxygenation bioreactor can controllably reduce dissolved oxygen in the circulating water, which is beneficial for the subsequent cultivation of anoxic microorganisms and the creation of a denitrification environment. The membrane oxygenation bioreactor completes the membrane attachment by using an oxygenation membrane and braided rope as carriers, forming a biological community of anoxic and aerobic layers from the outside to the inside on the surface of the oxygenation membrane, thereby achieving simultaneous nitrification and denitrification, and removing ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen. It has low energy consumption and solves the technical problems of high energy consumption and poor denitrification effect in the water treatment of recirculating aquaculture in the prior art. It achieves the technical effect of low energy consumption and controllable biofilm denitrification.

[0019] The high dissolved oxygen circulating water treatment system provided by this utility model can effectively remove nitrogen from high dissolved oxygen circulating water with low energy consumption. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of a denitrification bioreactor provided in one embodiment of the present invention; Figure 2 The membrane fiber surface of a membrane deoxygenation bioreactor provided in one embodiment of this utility model.

[0022] Icons: 1-Membrane tank; 2-Membrane degassing contactor; 3-Membrane deoxygenation bioreactor; 4-Membrane oxygen transfer bioreactor; 5-Membrane oxygenation contactor; 6-Vacuum pump; 7-Buffer tank; 8-Intermittent aeration device; 9-Air pump; 10-Pressurized pure oxygen. Detailed Implementation

[0023] The technical solution of this utility model will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0024] According to a first aspect of this utility model, a denitrification bioreactor is provided, see... Figure 1The membrane degassing contactor 2, the membrane deoxygenation bioreactor 3, the membrane oxygen transfer bioreactor 4, and the membrane oxygenation contactor 5 are arranged in sequence according to the water treatment process. Membrane degassing contactor 2 is used to remove carbon dioxide from water and adjust the pH of the water. Membrane deoxygenation bioreactor 3 is used to remove oxygen from water, providing suitable reaction conditions for the denitrification process; Membrane oxygen transfer bioreactor 4 is used to form an aerobic-anoxic biofilm layer to carry out simultaneous nitrification and denitrification reactions to remove ammonia nitrogen, nitrite nitrogen and nitrate nitrogen from the water; The membrane oxygenation contactor 5 is used to transfer oxygen into the water.

[0025] The denitrification bioreactor provided by this utility model simultaneously removes carbon dioxide from circulating water and adjusts the pH of the circulating water through a membrane degassing contactor; the membrane deoxygenation bioreactor can controllably reduce dissolved oxygen in circulating water, which is beneficial for the subsequent cultivation of anoxic microorganisms and provides conditions for denitrification reaction; the membrane oxygenation biofilm reactor completes the membrane attachment by using an oxygenation membrane and braided rope as carriers, forming a biological community of anoxic and aerobic layers from the inside to the outside on the surface of the oxygenation membrane, thereby realizing simultaneous nitrification and denitrification, and achieving the removal of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen.

[0026] In summary, the denitrification bioreactor of this invention can perform biofilm denitrification of high dissolved oxygen circulating water, achieving simultaneous nitrification and denitrification, effectively removing ammonia nitrogen and nitrate nitrogen, and with low energy consumption.

[0027] In a preferred embodiment, the membrane filament used in the membrane degassing contactor 2 can be a hollow fiber hydrophobic membrane with a surface pore size of less than 20 nm and a membrane diameter of less than 0.6 mm.

[0028] The membrane degassing contactor 2 can quickly and effectively remove carbon dioxide from circulating water without increasing the salinity of the water, maintaining the system pH stability and improving the nitrification effect.

[0029] In a preferred embodiment, the membrane deoxygenation bioreactor 3 includes a membrane tank 1, a deoxygenation membrane assembly immersed in the membrane tank, and a vacuum pump 6 connected to the deoxygenation membrane assembly.

[0030] It should be noted that the vacuum pump 6 is connected to the membrane degassing contactor 2 and the membrane deoxygenation bioreactor 3 via the buffer tank 7.

[0031] In a preferred embodiment, the deoxygenation membrane assembly can be composed of a plurality of hollow fiber membrane filaments, which can be woven into a net by braiding ropes. The spacing between the woven hollow fiber membrane filaments can be 0.1 mm to 1 mm, and the spacing between the braiding ropes can be 1 mm to 20 mm. The hollow fiber membrane filaments can be hydrophobic microporous membranes, and their pore size can be less than 20 nm.

[0032] It should be noted that the membrane surface of the membrane oxygenation bioreactor 4 can form a local anoxic zone, so that the denitrifying biological layer on the membrane surface can achieve denitrification, thereby reducing nitrate in the water; pure membrane denitrification is achieved through the biofilm attached to the oxygenation membrane surface, without the need to keep the entire membrane tank in an anoxic state, and without introducing pathogens, thus helping to maintain the safety of aquaculture organisms.

[0033] It should be noted that hollow fiber membranes have a high specific surface area, enabling a very high filling rate. When a hydrophobic microporous hollow fiber membrane is placed in water, a vacuum is created inside the membrane, forming a negative pressure. This causes gas in the water to continuously escape through the hollow fibers, achieving efficient carbon dioxide removal. Conversely, by filling the hollow fiber membrane with oxygen, the membrane surface in contact with the water can achieve efficient oxygen transfer, thus enabling precise control of dissolved oxygen in the water. When hollow fiber membranes are woven into a mesh, a biofilm can be formed on the membrane surface. By separately pumping or filling the membrane with oxygen from the inside, the microorganisms on the membrane surface can be controlled to undergo either anoxic or aerobic reactions, thereby achieving low-energy, controllable denitrification via biofilm.

[0034] In a preferred embodiment, the membrane degassing contactor 2, the membrane deoxygenation bioreactor 3, and the membrane oxygen transfer bioreactor 4 may also be independently equipped with an intermittent aeration device 8, which is used for intermittent aeration to flush the membrane surface.

[0035] In a preferred embodiment, the membrane oxygen transfer bioreactor 4 can be connected to an air pump on the inner side of the membrane; the membrane filaments used in the membrane oxygen transfer bioreactor 4 can be non-porous oxygen transfer membranes, which are woven into a mesh, with aerobic nitrifying bacteria on the inner side of the membrane surface and anoxic denitrifying bacteria on the outer side.

[0036] The coupled membrane oxygen transfer bioreactor 4 eliminates the need for constant aeration and oxygen supply, which is beneficial for improving the biofilm formation effect. It can achieve simultaneous nitrification and denitrification reactions, and its energy consumption is lower than that of MBBR.

[0037] In a preferred embodiment, the membrane filament used in the membrane oxygenation contactor 5 can be a hollow fiber hydrophobic membrane with a surface pore size of less than 20 nm and a membrane diameter of less than 0.6 mm.

[0038] In a preferred embodiment, the membrane fibers of the membrane oxygenation contactor 5 can be arranged laterally in the outlet pipe of the membrane tank; at the same time, the inner side of the membrane fibers of the membrane oxygenation contactor 5 can be connected to the pressurized pure oxygen 10.

[0039] A typical structure of a denitrification bioreactor is shown below. Figure 1 The membrane degassing contactor 2, the membrane deoxygenation bioreactor 3, the membrane oxygen transfer bioreactor 4, and the membrane oxygenation contactor 5 are arranged in sequence according to the water treatment process. The membrane degassing contactor 2 uses a hollow fiber hydrophobic membrane, the surface pore size of which is less than 20 nm and the diameter of which is less than 0.6 mm. Membrane deoxygenation bioreactor 3 and membrane oxygen transfer bioreactor 4 are used as denitrification biofilm reactors; Specifically, the membrane deoxygenation bioreactor 3 mainly consists of a membrane tank 1, a deoxygenation membrane module immersed in the membrane tank, and a vacuum pump 6 that is sealed and connected to the deoxygenation membrane module; Vacuum pump 6 is connected to membrane degassing contactor 2 and membrane deoxygenation bioreactor 3 via buffer tank 7; The deoxygenation membrane module is mainly composed of a hollow fiber membrane woven mesh, see Figure 2 The hollow fiber membrane is a hydrophobic microporous membrane with a pore size of less than 20 nm. When a vacuum is drawn inside the membrane, the concentration of dissolved oxygen on its surface is less than 0.5 mg / L. The spacing between the membrane fibers in the hollow fiber membrane mesh is 0.1 mm to 1 mm, and the spacing between the braided ropes is 1 mm to 20 mm. Intermittent aeration device 8 is provided in membrane degassing contactor 2, membrane deoxygenation bioreactor 3 and membrane oxygen transfer bioreactor 4. Intermittent aeration device 8 is used for intermittent aeration to flush the membrane surface. Specifically, the membrane oxygen transfer bioreactor 4 is mainly composed of a non-porous oxygen transfer membrane woven mesh, with the inner side of the membrane connected to an air pump. A membrane oxygenation contactor 5 is installed after the membrane oxygenation bioreactor 4 to efficiently transfer oxygen into the water. Among them, the membrane fiber used in the membrane oxygenation contactor 5 is a hollow fiber hydrophobic membrane, the surface pore size of which is less than 20nm and the diameter of which is less than 0.6mm. The membrane fibers of the membrane oxygenation contactor 5 are arranged laterally in the outlet pipe of the membrane tank, and the inner side of the membrane fibers of the membrane oxygenation contactor 5 is connected to the pressurized pure oxygen 10.

[0040] A water treatment method for high dissolved oxygen circulating water (dissolved oxygen above 5 mg / L), utilizing the denitrification bioreactor of this invention, includes the following steps: The high dissolved oxygen circulating water first undergoes membrane contact degassing, then denitrification biological reaction, and finally membrane contact oxygenation. Specifically, membrane contact degassing: removing carbon dioxide from raw water through a membrane degassing contactor; Specifically, denitrification biological reaction: removing dissolved oxygen from water through a membrane deoxygenation bioreactor to achieve the dissolved oxygen environment required for the denitrification reaction; Specifically, the aerobic biofilm layer formed on the surface of the oxygen transfer membrane in the membrane oxygen transfer bioreactor undergoes a denitrification reaction with the anoxic biofilm layer. Membrane contact oxygenation: Efficient oxygen transfer is achieved through a membrane oxygenation contactor.

[0041] According to a second aspect of the present invention, a high dissolved oxygen circulating water treatment system is provided, comprising the denitrification bioreactor described in any of the preceding claims.

[0042] The high dissolved oxygen circulating water treatment system provided by this utility model can effectively remove nitrogen from high dissolved oxygen circulating water with low energy consumption.

[0043] Example 1 A denitrification bioreactor, in sequence according to water treatment, includes a membrane degassing contactor, a membrane deoxygenation bioreactor, a membrane oxygen transfer bioreactor, and a membrane oxygenation contactor. The membrane degassing contactor uses a hollow fiber hydrophobic membrane with a surface pore size of 10 nm and a diameter of 0.3 mm. The membrane deoxygenation bioreactor mainly consists of a membrane tank, a deoxygenation membrane module immersed in the membrane tank, and a vacuum pump that is sealed and connected to the deoxygenation membrane module. The vacuum pump is connected to the membrane degassing contactor and the membrane deoxygenation bioreactor via a buffer tank; The deoxygenation membrane module is mainly composed of a hollow fiber membrane filament woven mesh. The hollow fiber membrane filament is a hydrophobic microporous membrane with a pore size of 10 nm. A vacuum is drawn inside the membrane, and the concentration of dissolved oxygen on its surface is less than 0.5 mg / L. The spacing between the membrane filaments in the hollow fiber membrane filament woven mesh is 0.5 mm, and the spacing between the braided ropes is 10 mm. Intermittent aeration devices are provided in membrane degassing contactors, membrane deoxygenation bioreactors, and membrane oxygen transfer bioreactors. The intermittent aeration devices are used for intermittent aeration to flush the membrane surface. The membrane oxygen transfer bioreactor is mainly composed of a non-porous oxygen transfer membrane woven mesh, with the inner side of the membrane connected to an air pump. A membrane oxygenation contactor is installed after the membrane oxygenation bioreactor to efficiently transfer oxygen into the water; The membrane oxygenation contactor uses a hollow fiber hydrophobic membrane with a surface pore size of 10 nm and a diameter of 0.3 mm. The membrane fibers of the membrane oxygenation contactor are arranged laterally in the outlet pipe of the membrane tank, and the inner side of the membrane fibers of the membrane oxygenation contactor is connected to the pressurized pure oxygen tank.

[0044] Example 2 This embodiment provides a denitrification bioreactor, which differs from Embodiment 1 only in that the hollow fiber hydrophobic membrane used in the membrane degassing contactor has a surface pore size of 15 nm. Everything else is the same as in Example 1.

[0045] Example 3 This embodiment provides a denitrification bioreactor, which differs from Embodiment 1 only in that the hollow fiber hydrophobic membrane used in the membrane degassing contactor has a surface pore size of 20 nm. Everything else is the same as in Example 1.

[0046] Example 4 This embodiment provides a denitrification bioreactor, which differs from Embodiment 1 only in that the hollow fiber hydrophobic membrane used in the membrane degassing contactor has a diameter of 0.6 mm. Everything else is the same as in Example 1.

[0047] Example 5 This embodiment provides a denitrification bioreactor, which differs from Embodiment 1 only in that the hollow fiber membrane filaments used in the deoxygenation membrane assembly have a pore size of 15 nm. Everything else is the same as in Example 1.

[0048] Example 6 This embodiment provides a denitrification bioreactor, which differs from Embodiment 1 only in that the hollow fiber membrane filaments used in the deoxygenation membrane assembly have a pore size of 20 nm. Everything else is the same as in Example 1.

[0049] Example 7 This embodiment provides a denitrification bioreactor, which differs from Embodiment 1 only in that the hollow fiber membrane filament mesh used in the deoxygenation membrane assembly has a membrane filament spacing of 0.1 mm and a braided rope spacing of 20 mm. Everything else is the same as in Example 1.

[0050] Example 8 This embodiment provides a denitrification bioreactor, which differs from Embodiment 1 only in that the hollow fiber membrane filament mesh used in the deoxygenation membrane assembly has a membrane filament spacing of 1 mm and a braided rope spacing of 1 mm. Everything else is the same as in Example 1.

[0051] Example 9 This embodiment provides a denitrification bioreactor, which differs from Embodiment 1 only in that the membrane deoxygenation bioreactor does not have an intermittent aeration device. Everything else is the same as in Example 1.

[0052] Compared with Example 1, the drawback of this example is that it cannot intermittently aerate and wash the membrane surface.

[0053] Comparative Example 1 This comparative example provides a denitrification bioreactor, which differs from Example 1 only in that it does not include a membrane degassing contactor; Everything else is the same as in Example 1.

[0054] Compared with Example 1, the drawback of this comparative example is that it is not conducive to removing carbon dioxide from the water and cannot adjust the pH of the water, which leads to the need to add carbon source in the subsequent denitrification process.

[0055] Comparative Example 2 This comparative example provides a denitrification bioreactor, which differs from Example 1 only in that it does not include a membrane deoxygenation bioreactor. Everything else is the same as in Example 1.

[0056] Compared with Example 1, the drawback of this comparative example is that it cannot provide an anoxic environment for the reactor and therefore cannot carry out anoxic denitrification.

[0057] Comparative Example 3 This comparative example provides a denitrification bioreactor, which differs from Example 1 only in that it does not include a membrane oxygen transfer bioreactor. Everything else is the same as in Example 1.

[0058] Compared with Example 1, the drawback of this comparative example is that it cannot form a biofilm for simultaneous nitrification and denitrification, and therefore cannot carry out denitrification reactions.

[0059] Comparative Example 4 This comparative example provides a denitrification bioreactor, which differs from Example 1 only in that it does not include a membrane oxygenation contactor; Everything else is the same as in Example 1.

[0060] Compared to Example 1, the drawback of this comparative example is that it is difficult to effectively transfer oxygen into the water.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A denitrification bioreactor, characterized in that, The water treatment process includes, in sequence, a membrane degassing contactor, a membrane deoxygenation bioreactor, a membrane oxygen transfer bioreactor, and a membrane oxygenation contactor. The membrane degassing contactor is used to remove carbon dioxide from water and adjust the pH of the water. The membrane deoxygenation bioreactor is used to remove oxygen from the water, providing suitable reaction conditions for the denitrification process; The membrane oxygen transfer bioreactor is used to form an aerobic-anoxic biofilm layer to carry out simultaneous nitrification and denitrification reactions to remove ammonia nitrogen, nitrite nitrogen and nitrate nitrogen from the water; The membrane oxygenation contactor is used to transfer oxygen into the water.

2. The denitrification bioreactor according to claim 1, characterized in that, The membrane degassing contactor uses hollow fiber hydrophobic membranes.

3. The denitrification bioreactor according to claim 2, characterized in that, The surface pore size of the hollow fiber hydrophobic membrane is less than 20 nm; The diameter of the hollow fiber hydrophobic membrane is less than 0.6 mm.

4. The denitrification bioreactor according to claim 1, characterized in that, The membrane deoxygenation bioreactor includes a membrane tank, a deoxygenation membrane module immersed in the membrane tank, and a vacuum pump that is sealed and connected to the deoxygenation membrane module. The vacuum pump is connected to the membrane degassing contactor and the membrane deoxygenation bioreactor via a buffer tank.

5. The denitrification bioreactor according to claim 4, characterized in that, The deoxygenation membrane assembly includes a hollow fiber membrane woven mesh.

6. The denitrification bioreactor according to claim 5, characterized in that, The hollow fiber membrane filaments include hydrophobic microporous membranes; The pore size of the hollow fiber membrane filament is less than 20 nm; The spacing between the membrane filaments in the hollow fiber membrane woven mesh is 0.1mm to 1mm, and the spacing between the woven ropes is 1mm to 20mm.

7. The denitrification bioreactor according to claim 1, characterized in that, The membrane degassing contactor, membrane deoxygenation bioreactor, and membrane oxygen transfer bioreactor are also independently equipped with intermittent aeration devices for intermittent aeration to flush the membrane surface.

8. The denitrification bioreactor according to claim 1, characterized in that, The inner side of the membrane in the membrane oxygen transfer bioreactor is connected to an air pump. The membrane oxygen transfer bioreactor includes a non-porous oxygen transfer membrane woven mesh.

9. The denitrification bioreactor according to claim 1, characterized in that, The membrane filaments used in the membrane oxygenation contactor include hollow fiber hydrophobic membranes. The surface pore size of the hollow fiber hydrophobic membrane is less than 20 nm; The diameter of the hollow fiber hydrophobic membrane is less than 0.6 mm; The membrane fibers of the membrane oxygenation contactor are arranged laterally in the outlet pipe of the membrane tank; The inner side of the membrane fiber of the membrane oxygenation contactor is connected to the pressurized pure oxygen tank.

10. A high dissolved oxygen circulating water treatment system, characterized in that, Includes the denitrification bioreactor as described in any one of claims 1-9.

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