High-nitrogen high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles

Abstract

The invention provides a high-nitrogen high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles, which comprises an electric biological filler unit suspended in an anoxic denitrification water tank, at least one stage of shaftless aeration water impeller below the electric biological filler unit, a gas tank storing CO2 and a bubble stabilizing liquid storage bin, wherein the shaftless aeration water impeller comprises a rotatable shaftless multi-column tooth structure and shaftless propeller blades which are axially and sequentially arranged, and is used for mixing CO2 introduced into the shaftless aeration water impeller with high-nitrogen and high-hardness wastewater in the anoxic denitrification water tank, carrying out flow pushing, carrying out multi-round gradient cutting and refining to form micro-nano CO2 bubbles, and outputting the micro-nano CO2 bubbles. By means of the mixed design of the shaftless propeller blades and the shaftless multi-column-tooth structure, a high-frequency cutting structure is formed, the bubble stabilizing liquid is supplemented, the electric biological filler and the micro-nano CO2 bubbles are combined and applied to the anoxic denitrification water tank, the aeration plug flow performance is excellent, the denitrification efficiency is high, and the denitrification effect is good. The problem of poor denitrification and descaling effects of high-nitrogen and high-hardness wastewater is solved.

Description

Technical Field

[0001] This application relates to the field of industrial wastewater treatment technology, and in particular to a high-nitrogen, high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles. Background Technology

[0002] Industrial wastewater from electroplating circuit boards, capacitor production, and thermal power plant desulfurization is characterized by high hardness, high nitrogen content, and complex composition. Hardness (Ca) is a significant factor. 2+ Mg 2+ The concentration of nitrate nitrogen often reaches 500-5000 mg / L (calculated as CaCO3), the total nitrogen (TN) concentration is 100-500 mg / L, and the proportion of nitrate nitrogen is high. It also contains pollutants such as heavy metal ions and complex organic matter, making it extremely difficult to treat.

[0003] Among existing denitrification technologies, biological denitrification has become the mainstream solution due to its low cost and environmental friendliness. However, high-nitrogen and high-hardness wastewater easily leads to scaling and clogging of biological packing materials, damaging the biofilm structure and causing a significant decrease in denitrification efficiency (usually below 60%). Therefore, the biofilm method has long been considered difficult to apply to the treatment of high-nitrogen and high-hardness wastewater. Chemical denitrification technologies (such as breakpoint chlorination) have problems such as large reagent dosage, high sludge production, and secondary pollution. Physical denitrification technologies (such as membrane separation) have the drawbacks of severe membrane fouling and high operating costs, making them difficult to apply on a large scale.

[0004] Hydrogen autotrophic denitrification technology uses inorganic carbon as a carbon source and hydrogen as an electron donor, eliminating the need for additional organic carbon sources and producing low sludge production. It is suitable for treating high-salt, high-nitrogen, and high-hardness wastewater. However, traditional hydrogen autotrophic denitrification has two major bottlenecks: first, the supply of inorganic carbon sources is insufficient, requiring the addition of inorganic carbon sources such as sodium bicarbonate, which increases treatment costs; second, the mass transfer efficiency is low, and the low solubility of hydrogen leads to a slow reaction rate, complex equipment, and potential safety hazards.

[0005] Micro-nano bubble technology is gradually being applied in the field of water treatment due to its advantages such as large specific surface area (100-1000 times that of ordinary bubbles), high mass transfer efficiency, and long residence time. However, existing technologies mostly focus on oxygenation and aeration. Moreover, existing micro-nano bubble generators are mostly split structures, occupying a large area, and have poor bubble stability (residence time is usually less than 30 minutes), making it difficult to meet the long-term operation requirements of treating high-nitrogen and high-hardness wastewater.

[0006] Therefore, it is necessary to address the aforementioned shortcomings. Summary of the Invention

[0007] The purpose of this application is to overcome the shortcomings of the prior art and provide a high-nitrogen, high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles.

[0008] This application provides a high-nitrogen, high-hardness wastewater denitrification system based on micro / nano carbon dioxide bubbles, comprising: The electrobiological packing unit is suspended in the anoxic denitrification tank. At least one shaftless aerator is installed in the anoxic denitrification tank and located below the electrobiological packing unit. The shaftless aerator includes a shaftless multi-column tooth structure and shaftless propeller blades arranged axially in sequence and rotating together. The carbon dioxide gas introduced into the shaftless aerator and the wastewater drawn into the anoxic denitrification tank form a gas-liquid mixture in the shaftless aerator. After being subjected to multiple rounds of gradient collision, cutting, dissolving, tearing and refining by the shaftless multi-column tooth structure, the mixture is further stirred, broken and refined by the shaftless propeller blades, and finally formed into a micro-nano carbon dioxide bubble mixture before being pushed out. A gas tank, which stores carbon dioxide gas, is connected to an air inlet pipe, through which the carbon dioxide gas is introduced into the shaftless aerator. A bubble stabilizing liquid storage chamber stores bubble stabilizing liquid containing compound stabilizers. It is connected to an inlet pipe, through which the bubble stabilizing liquid in the bubble stabilizing liquid storage chamber is introduced into the shaftless aerator.

[0009] In some embodiments of the high-nitrogen, high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles provided in this application, the mass percentage of the compound stabilizer in the bubble stabilizing liquid is: polyethylene glycol 0.5-2%; sodium carboxymethyl cellulose 0.3-1%; AA / AMPS sulfonate organic copolymer 0.1-1%; the balance being water.

[0010] In some embodiments of a high-nitrogen, high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles provided in this application, the electrobiological packing unit includes a conductive cathode packing and a metal anode support, wherein the conductive cathode packing is suspended on the metal anode support.

[0011] In some embodiments of the high-nitrogen, high-hardness wastewater denitrification system based on micro / nano carbon dioxide bubbles provided in this application, the shaftless aeration mixer further includes: An outer cylinder having a first inner cavity, with an inlet on one axial side of the outer cylinder communicating with the first inner cavity, wherein the outer cylinder of the first-stage shaftless aerator is radially connected to the air inlet pipe, so that carbon dioxide gas and wastewater entering the first inner cavity of the first-stage shaftless aerator vertically converge to form a gas-liquid mixture; An inner cylinder disposed within the first inner cavity and driven to rotate, the inner cylinder having a second inner cavity; The shaftless multi-column tooth structure is disposed on the inner wall of the second inner cavity and is driven by the inner cylinder to rotate at high speed. It is used to perform multiple rounds of gradient collision, cutting, dissolving, tearing and refining of the gas-liquid mixture in the first inner cavity to generate a large number of microbubbles. It includes multiple spaced toothed pillars, which are arranged in an array along the inner wall of the second inner cavity. The bottom of each toothed pillar is fixed to the inner wall of the second inner cavity and extends radially towards the center of the inner cylinder to form a top. The radial gap between the tops of each toothed pillar forms a first water passage at the center of the second inner cavity. At least two shaftless propeller blades are disposed on the inner wall of the second inner cavity and rotated by the inner cylinder. They are used to entrain the gas-liquid mixture to form a vortex turbulence and to further stir, cut and break the mixture with microbubbles after it has been cut by the shaftless multi-column tooth structure, further refining it into a micro-nano carbon dioxide bubble mixture and pushing it forward. The root of each shaftless propeller blade is fixed on the inner wall of the second inner cavity, and the tip faces the center of the second inner cavity. The radial gap between the tips of each shaftless propeller blade forms a second water passage at the center of the second inner cavity. The outer cylinder is also provided with a bubble output chamber for outputting the micro-nano carbon dioxide bubble mixture pushed out by the shaftless propeller blades.

[0012] In some embodiments of the high-nitrogen, high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles provided in this application, each of the toothed support pillars is a cubic structure with the inner sidewall of the second inner cavity as the base and approximately in the shape of an equilateral trapezoid; or a pyramidal structure with a polygonal base.

[0013] In some embodiments of the high-nitrogen, high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles provided in this application, each of the toothed support columns is arranged radially spaced around the inner wall of the second inner cavity, and is arranged in layers at axial intervals along the inner wall of the second inner cavity, with the toothed support columns arranged in each layer on the same axial line; or, each of the toothed support columns is arranged radially spaced around the inner wall of the second inner cavity, and is arranged in layers at axial intervals along the inner wall of the second inner cavity, with the toothed support columns arranged in adjacent layers being axially offset.

[0014] In some embodiments of the high-nitrogen, high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles provided in this application, the number of radial columns of each of the toothed pillars surrounding the second inner cavity is 4-8, and the number of axial rows along the second inner cavity is 5-10.

[0015] In some embodiments of the high-nitrogen, high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles provided in this application, the outer wall of the inner cylinder is covered with a magnetic sleeve, and an inductor coil connected to a power source is fixed around the inner wall of the outer cylinder, corresponding to the magnetic sleeve, so that the inner cylinder is suspended in the first inner cavity and rotates at high speed in the first inner cavity under the magnetic drive of the inductor coil.

[0016] In some embodiments of the high-nitrogen, high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles provided in this application, sealed bearings are respectively provided at both ends of the inductor coil along the axial direction. The outer rings of the two sealed bearings are fixed on the inner wall of the outer cylinder, and the inner rings are fixed at the two outer ends of the inner cylinder along the axial direction, rotating with the inner cylinder.

[0017] In some embodiments of the high-nitrogen, high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles provided in this application, the gas tank is equipped with a flow regulating valve and a pressure reducing valve, and the bubble stabilizing liquid storage tank is equipped with a liquid adding pump.

[0018] This application has the following technical effects: (1) Good scale inhibition effect: Combining electrobiological packing with micro-nano carbon dioxide bubbles, which dissolve to form carbonic acid, can reduce the pH value of water to 6.5-7.5. At the same time, when carbon dioxide gas is introduced into the shaftless aerator, a bubble stabilizing liquid is added, which gives the micro-nano carbon dioxide bubbles high specific surface area, strong adsorption capacity and long retention time, and efficiently captures Ca in the water. 2+ Mg 2+ Isocations, inhibiting Ca 2+ Mg 2+ It combines with carbonate and hydroxide ions to form crystalline deposits. When the micro-nano carbon dioxide bubbles burst, the resulting strong micro-jet and impact can effectively break up the already formed loose scale layer, achieving the effect of "targeted descaling". It will not damage the polysaccharide matrix of the biofilm, solving the scaling problem of biological packing in high-nitrogen and high-hardness wastewater. It breaks the traditional thinking that the biofilm method is difficult to apply to the treatment of high-nitrogen and high-hardness wastewater. The system has been running continuously for 30 days without significant scaling.

[0019] (2) Excellent aeration and flow propulsion performance: The shaftless aerator adopts a shaftless suction mixing design. The high-speed rotation of the shaftless propeller blades and shaftless multi-column tooth structure generates a negative pressure suction effect, continuously drawing carbon dioxide gas into the liquid phase, improving the gas-liquid mixing efficiency, and avoiding the flow field turbulence caused by the shafted structure. At the same time, combined with the high-speed rotating toothed support columns of the shaftless multi-column tooth structure, the toothed support columns are arranged in an array to form multiple rounds of gradient high-frequency collision, cutting, tearing and refining of the gas-liquid mixture. Then, through the stirring of the shaftless propeller blades and the vortex turbulence pressurization effect of the central water passage of the shaftless multi-column tooth structure, the microbubbles generated after collision and cutting are further cut and broken during stirring, and further refined, and from the vortex The flow center flows out smoothly, achieving efficient mass transfer between gas and liquid phases and precise bubble control. The prepared micro-nano carbon dioxide bubbles have uniform particle size and strong stability, solving the technical problems of large bubble size, uneven distribution, poor stability and dispersed structure in traditional micro-nano bubble mixture preparation systems. Energy consumption is reduced by 30%-50% compared with traditional technology. The dissolved gas efficiency of the prepared micro-nano carbon dioxide bubbles is 5-10 times that of ordinary oxygen bubbles, and its carbon dioxide utilization rate reaches more than 32%. It provides sufficient inorganic carbon source for the cathode hydrogen evolution autotrophic denitrification system. At the same time, it uses the COD of wastewater as an organic carbon source to achieve hydrogen autotrophic-heterotrophic coupling denitrification without the need for additional carbon source, reducing treatment costs by 30-50%.

[0020] (3) High denitrification efficiency: The micro-nano carbon dioxide bubbles formed by the shaftless aerator and the bubble stabilizing liquid work together to enhance the mass transfer of micro-nano carbon dioxide bubbles. The bubble particle size is controlled at 1-50μm, and the rising speed in water is extremely slow, extending the residence time to 2-4h. Combined with the electrobiological packing to catalyze the hydrogen evolution reaction, the denitrification efficiency of nitrate in the residual sludge cell-breaking liquid is improved, and COD degradation is achieved at the same time. The total nitrogen removal rate is ≥85%, which can reach more than 90% in the treatment of electroplating circuit board wastewater, greatly improving the wastewater treatment effect.

[0021] (4) Integrated design: When the shaftless aerator is vertically installed in the anoxic denitrification tank, the 10 cubic meter tank volume occupies only 1-2 square meters. The structure is compact and suitable for on-site installation and operation and maintenance in industrial enterprises. Compared with the split equipment, it occupies less area and reduces investment costs.

[0022] (5) Wide range of applications: It can be adapted to various high-nitrogen and high-hardness wastewaters such as electroplating circuit boards, capacitor production, thermal power desulfurization, and high-salt chemical wastewaters. It can operate independently or be integrated into A 2 The denitrification stage of / O, MBR, and SBR processes has a hydraulic retention time of 4-10 hours to adapt to different water quality fluctuations. Attached Figure Description

[0023] Figure 1This is a schematic diagram of an embodiment of a high-nitrogen, high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles provided in this application; Figure 2 This is a schematic diagram of the electrobiological packing unit structure in the embodiment of the high-nitrogen and high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles in this application; Figure 3 This is a schematic diagram of the first-stage shaftless aerator in the embodiment of the high-nitrogen and high-hardness wastewater denitrification system based on micro-nano carbon dioxide bubbles in this application; Figure 4 for Figure 3 AA section view; In the picture: 1-Anoxic denitrification tank; 11-Tank inlet; 12-Tank outlet; 2-Electro-biological packing unit; 21-Conductive cathode packing; 22-Metal anode support; 23-Packing suspension rope; 3-DC power supply; 4-Staff; 5-Shaftless aeration propeller; 5a - First-stage shaftless aerator; 5b - Second-stage shaftless aerator; 51-Outer cylinder; 510-First inner cavity; 5101-Water inlet; 511-First cylinder body; 5111-Mixing chamber; 512 - Second cylinder; 513 - Third cylinder; 5131 - Water outlet chamber; 52-Inner cylinder; 521-Second inner cavity; 5211-First water passage; 5212-Second water passage; 53-Shaftless multi-column tooth structure; 531-Toothed support column; 5311-Bottom; 5312-Top; 54 - Shaftless propeller blade; 541 - Root; 542 - Tip; 55 - Inductor coil; 56 - Magnetic sleeve; 57 - Sealed bearing; 58 - Water outlet pipe; 59 - Water suction pipe; 591 - Suction hole; 6-Gas cylinder; 61-Inlet pipe; 62-Flow regulating valve; 63-Pressure reducing valve; 7-Bubble stabilizer storage tank; 71-Agitator blades; 72-Stabilizer suction pipe; 73-Liquid addition pump; 74-Liquid addition tube. Detailed Implementation

[0024] The specific embodiments of this application will be further described in detail below with reference to the accompanying drawings and examples. The following embodiments are used to illustrate this application, but are not intended to limit the scope of this application. Similarly, the following embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "upper," "lower," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," "upper end," "lower end," and "side end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between the components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above" or "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below" or "below" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0029] In this invention, the terms "one embodiment" or "some embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment, which are included in at least one embodiment of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments. Moreover, those skilled in the art can combine and integrate the different embodiments described in this specification and the features of the different embodiments without contradiction.

[0030] In this invention, the term "generally presents" describes the main features of an overall structure or shape. When describing the shape of an object, this means that the object primarily presents a certain shape, but may differ in non-functional details. These differences in detail do not affect the overall features and can therefore be categorized as "generally presents" a certain shape. For example, when describing a cylindrical object, stating "generally cylindrical" means that the overall shape of the object is cylindrical, but there are differences in some non-functional details. Similarly, when describing a cube, stating "generally cubic" means that the overall shape of the object is cubic, but there are differences in some non-functional details.

[0031] The following describes some specific implementation schemes of this application with reference to the accompanying drawings.

[0032] See Figure 1 This application provides a high-nitrogen, high-hardness wastewater denitrification system based on micro / nano carbon dioxide bubbles, comprising: The electrobiological packing unit 2 is connected to the DC power supply 3 and is suspended by the packing rope 23, so that the electrobiological packing unit 2 is suspended in the anoxic denitrification tank 1 and submerged in the wastewater of the anoxic denitrification tank 1. The anoxic denitrification tank 1 adopts a cubic structure, with the tank inlet 11 located at the bottom end of the side wall of the anoxic denitrification tank 1 and the tank outlet 12 located at the top end of the side wall of the anoxic denitrification tank 1.

[0033] At least one shaftless aerator 5 is installed below the electro-biological packing unit 2 and supported by a bracket 4 installed at the bottom of the anoxic denitrification tank 1. It can be installed vertically as shown in the figure or horizontally, and is submerged in the wastewater in the anoxic denitrification tank 1. The shaftless aerator 5 includes a shaftless multi-tooth structure 53 arranged axially and rotating together, and a shaftless propeller blade 54. The shaftless propeller blade 54 is used to mix and aerate the carbon dioxide gas introduced into the shaftless aerator 5 and the wastewater drawn into the anoxic denitrification tank 1 in the shaftless aerator 5. At the same time, it propels the mixed gas and liquid mixture forward (pushing the flow). The shaftless multi-tooth structure 53 further pushes the gas and liquid mixture while performing multiple rounds of gradient cutting, dissolving, collision, tearing and refining on the gas and liquid mixture. After being stirred and further broken and refined by the shaftless propeller blade 54 to form a micro-nano carbon dioxide bubble mixture, it is pushed out and enters the next stage shaftless aerator 5 or is exchanged in the anoxic denitrification tank 1.

[0034] Gas tank 6 stores carbon dioxide gas and is connected to an air inlet pipe 61. The other end of the air inlet pipe 61 is connected to the shaftless aerator 5. Through the air inlet pipe 61, the carbon dioxide gas in the gas tank 6 can be introduced into the shaftless aerator 5.

[0035] The bubble stabilizing liquid storage tank 7 stores bubble stabilizing liquid containing a compound stabilizer. This compound stabilizer is used to regulate the gas-liquid interface characteristics, prolong bubble dissolution time, improve bubble stability, and reduce the concentration of scale-forming ions in the wastewater. The bubble stabilizing liquid storage tank 7 is connected to an inlet pipe 71, the other end of which is connected to the shaftless aerator propeller 5, or via a T-junction and inlet pipe 61. The bubble stabilizing liquid in the bubble stabilizing liquid storage tank 7 can be introduced into the shaftless aerator propeller 5 through the inlet pipe 71.

[0036] In the aforementioned system of this application, the anoxic denitrification tank 1 can be a vertical structure, with at least one stage of shaftless aerator 5 vertically installed at the bottom and an electrobiological packing unit 2 arranged at the top, forming a coupled reaction zone of "bottom heterotrophic denitrification + upper hydrogen autotrophic denitrification". This allows the electrobiological packing to combine with the micro-nano carbon dioxide bubbles generated by the shaftless aerator 5, dissolving to form carbonic acid, effectively reducing the pH value of the water (pH 6.5-7.5), and inhibiting calcium... 2+ Mg 2+The carbon dioxide bubbles combine with carbonate and hydroxide ions to form crystalline deposits. At the same time, the micro-nano carbon dioxide bubbles, combined with the compound stabilizers in the bubble stabilizing liquid, reduce the concentration of scale-forming ions in the wastewater through electrostatic adsorption, change the existence form of scale-forming ions, and promote their existence in a soluble form. When the micro-nano carbon dioxide bubbles burst, they physically destroy the scale layer through micro-jet and shock wave, thus solving the scaling problem of biological packing in high-nitrogen and high-hardness wastewater. Meanwhile, the electro-biological packing unit 2 catalyzes the hydrogen evolution reaction, coupling hydrogen autotrophic bacteria (using CO2 as a carbon source) and heterotrophic bacteria (using the COD in the wastewater as a carbon source) for efficient denitrification. The shaftless aerator 5 adopts a shaftless suction mixing design. The high-speed rotation of the shaftless propeller blades 54 and the shaftless multi-column tooth structure 53 generates a negative pressure suction effect, which improves the gas-liquid mixing efficiency, reduces the energy consumption ratio, and provides excellent aeration and propulsion performance. It avoids the flow field turbulence caused by traditional shafted structures. At the same time, the shaftless multi-column tooth structure 53 and the shaftless propeller blades 54 form a multi-round gradient high-frequency cutting structure, which allows the mixture with microbubbles formed after collision, cutting, and tearing to flow out from the center of the vortex. It adapts to the gradual refinement of bubbles and can prepare finer, more uniform micro-nano carbon dioxide bubbles (average particle size ≤100nm). Combined with bubble stabilizing liquid, it enhances the bubble stability and delayed retention characteristics (24h particle size change rate ≤5%). It solves the technical problems of large bubble size, uneven distribution, poor stability and dispersed structure in traditional micro-nano bubble mixture preparation systems. Its carbon dioxide utilization rate reaches more than 32%, which improves the scale inhibition effect of wastewater.

[0037] In some embodiments of this application, the mass percentage of the compounded stabilizer in the bubble stabilizing liquid is: polyethylene glycol 0.5-2%; sodium carboxymethyl cellulose 0.3-1%; AA / AMPS sulfonate organic copolymer 0.1-1%; with the balance being water, so that the total mass percentage of the bubble stabilizing liquid is 100%. Polyethylene glycol (PEG) has good solubilizing and dispersing properties, sodium carboxymethyl cellulose has thickening, film-forming, binding, moisture retention, colloidal protection, emulsifying, and suspending effects, and the AA / AMPS sulfonate organic copolymer is a highly efficient scale inhibitor and dispersant.

[0038] See Figure 2 In some embodiments of this application, the electrobiological packing unit 2 includes a conductive cathode packing 21 and a metal anode support 22. The conductive cathode packing 21 serves as a carrier for hydrogen-evolving denitrifying bacteria and is suspended within the metal anode support 22. The metal anode support 22 is made of one or more of titanium alloy, stainless steel, or aluminum alloy. When the electrobiological packing unit 2 is applied to a vertical anoxic denitrification tank 1 with a structure of 1m×1m×1.8m, the surface area of ​​the conductive cathode packing 21 is 10-20㎡, and the operating voltage after connection to the DC power supply 3 is 0.5-1.5V, with an adjustable current of 50-300A.

[0039] This application combines electrobiological fillers, micro / nano carbon dioxide bubbles, and the aforementioned compound stabilizers in a synergistic manner, achieving the following effects: (1) The AA / AMPS copolymer in the compound stabilizer has chelating, lattice distortion and dispersion stabilizing properties. Its carboxyl group (-COOH) and sulfonic acid group (-SO3H) are the core functional groups, which can react with Ca 2+ Mg 2+ The scale-forming ions form stable chelate complexes. Regarding the lattice distortion mechanism, they can adsorb onto the active growth points of calcium carbonate crystals, interfering with the normal crystal growth process and causing distortion. In-situ atomic force microscopy (AFM) observations confirmed that the AA / AMPS copolymer can form an adsorption layer on the calcite (104) crystal surface, preventing crystal growth along the c-axis and causing the crystal morphology to change from a regular rhombohedron to an irregular spherical or dendritic structure.

[0040] (2) The combination of stabilizer and micro / nano carbon dioxide bubbles can give the micro / nano carbon dioxide bubbles a high specific surface area and strong adsorption capacity: the specific surface area of ​​the micro / nano carbon dioxide bubbles can reach 10 4 -10 5 m 2 / m 3 Its surface carries a negative charge (Zeta potential of approximately -30 to -50 mV), enabling it to efficiently capture Ca from water through electrostatic adsorption. 2+ Mg 2+ Isocations. Under pH 7.0 conditions, a single micro / nano carbon dioxide bubble can adsorb 12-15 mg / g of metal ions.

[0041] (3) Compound stabilizers can improve the long residence time and slow-release effect of micro-nano carbon dioxide bubbles: Compared with conventional micron bubbles, micro-nano carbon dioxide bubbles rise at a very slow speed in water (following Stokes' law, the speed is proportional to the square of the particle size), and can remain in water for 2-4 hours or even longer. This long residence characteristic allows carbon dioxide to continuously dissolve and participate in chemical reactions, while the bubbles continuously release carbon dioxide during their rise, forming a slow-release effect. When micro-nano carbon dioxide bubbles burst, they generate strong micro-jet streams and shock waves, with energy concentrated in the range of 10-20 μm. This local high-energy effect can effectively break up the already formed loose scale layer without damaging the polysaccharide matrix of the biofilm, achieving the effect of "targeted descaling".

[0042] (4) Micro-nano carbon dioxide bubble coupled electro-biological packing unit 2 denitrification: It can synergistically improve the denitrification efficiency of nitrate in the residual sludge cell-breaking liquid, and at the same time realize COD degradation. It utilizes the external electric field of the biological packing in the electro-biological packing unit 2 to regulate the microenvironment and electron transfer. Under the applied low voltage of 0.8 to 1.2 V, the cathode undergoes a reduction reaction (2H2O + 2e-). - =H2+2OH - The process raises the pH in the cathode region, creating a slightly alkaline environment suitable for denitrifying bacteria. The weak oxidation at the anode decomposes large organic molecules in the sludge cell-breaking liquid, converting them into small carbon sources easily utilized by microorganisms. Simultaneously, the reaction byproducts (H2) released from the electrodes act as electron acceptors / donors, directly or indirectly providing electrons to denitrifying bacteria, accelerating the conversion of nitrate to nitrogen (2NO3). - +10e - +12H + =N2↑+6H2O), avoiding the problem of insufficient electron donors in traditional biological denitrification. Due to their small particle size (100-500 nm) and large specific surface area, micro- and nano-sized carbon dioxide bubbles have a long residence time in water, allowing them to quickly dissolve and diffuse into the biofilm. On the one hand, the reaction products of carbon dioxide (HCO3-) - The electrobiomass packing unit 2 provides ample inorganic carbon sources for facultative denitrifying bacteria and a continuous source for hydrogen autotrophic denitrification, promoting the continuous denitrification reaction. On the other hand, the cavitation effect of micro- and nano-sized carbon dioxide bubbles generates microjets and localized high temperatures and pressures, assisting in the destruction of sludge cell structures, releasing intracellular nitrogen and carbon substances, and improving the biodegradability of pollutants. Furthermore, dissolved carbon dioxide can regulate the pH of the system, preventing excessively high pH in the cathode area from inhibiting microbial activity. Moreover, the micro-electric field generated by the electrochemical action of the electrobiomass packing unit 2 stimulates the enzyme activity of denitrifying bacteria (such as nitrate reductase and nitrite reductase), accelerating nitrogen metabolism. The mass transfer enhancement effect of micro- and nano-sized carbon dioxide bubbles shortens the contact mass transfer resistance between the substrate and microorganisms; the synergistic effect of both significantly increases the metabolic rate of denitrifying bacteria. Simultaneously, the biofilm formed on the electrode surface combines with the electrochemically active sites to construct a highly efficient "electrode-biofilm-pollutant" reaction interface, enabling rapid nitrate removal.

[0043] (5) The coupling effect between carbon dioxide and bubble stabilizer in micro-nano carbon dioxide bubbles can also improve the carbon source supply function: HCO3 produced after the micro-nano carbon dioxide bubbles dissolve - It can be directly used as an inorganic carbon source for hydrogen autotrophic denitrifying bacteria. Introducing micro-nano carbon dioxide bubbles into the anaerobic section of electroplating wastewater can increase the HCO3 content of the water. - When the concentration is stabilized at 50-100 mg / L, the rate of hydrogen autotrophic denitrification increases by 25%-30%.

[0044] See Figure 3 In some embodiments of this application, the shaftless aeration propeller 5 includes: The outer cylinder 51 has a first inner cavity 510. On one side of the outer cylinder 51 along the axial direction, there is an inlet 5101 that communicates with the first inner cavity 510. The inlet 5101 can axially introduce wastewater from the anoxic denitrification tank 1 into the first inner cavity 510. At the water inlet end of the outer cylinder 51 of the first-stage shaftless aerator 5a, there is a radial air intake channel for external carbon dioxide gas. The air intake channel is equipped with an air intake pipe 61. One end of the air intake pipe 61 extends radially along the side wall of the outer cylinder 51 into the first inner cavity 510 and communicates with the first inner cavity 510. The other end of the air intake pipe 61 is connected to the gas tank 6. When wastewater enters through inlet 5101, carbon dioxide gas also enters the first inner cavity 510 through inlet pipe 61. It mixes perpendicularly with the water flow entering the first inner cavity 510 through inlet 5101, with a gas-water volume ratio of 1:50 to 100. This forms a gas-liquid mixing chamber 5111 at the water inlet end of the first inner cavity 510, thereby improving the carbon dioxide gas dissolution efficiency.

[0045] See also Figure 1 The outer cylinder 51 is specifically composed of a first cylinder 511, a second cylinder 512, and a third cylinder 513 arranged in sections, which are axially combined and fixedly connected in sequence. The cylinder walls of the first cylinder 511 and the second cylinder 512, and the second cylinder 512 and the third cylinder 513 are connected to each other. The first cylinder 511 is the water inlet section, which includes a conical cylinder structure with the small end located at the water inlet. The water inlet 5101 is axially located at the top of the conical cylinder of the first cylinder 511. One end of the air inlet pipe 61 extends radially into the first inner cavity 510 along the side wall of the first cylinder 511. The gas-liquid mixing chamber 5111 is located inside the first cylinder 511. The second cylinder 512 is the working section, which is roughly cylindrical. The third cylinder 513 is the output section, which includes a conical cylinder structure with the small end located at the bubble output chamber 5131. The water outlet pipe 58 for the micro-nano carbon dioxide bubble mixture is connected to the small end of the conical cylinder of the third cylinder 513. Inside the second cylindrical body 512, an inner cylinder 52 is provided, which has a second inner cavity 521. The outer circumference of the inner cylinder 52 is consistent with the shape of the inner cavity of the second cylindrical body 512 but smaller than the diameter of the inner cavity of the second cylindrical body 512. It can be driven to rotate within the inner cavity of the second cylindrical body 512. The shaftless multi-column tooth structure 53 and the shaftless propeller blade 54 are both fixed inside the inner cylinder 52 and rotate with the inner cylinder 52 within the second cylindrical body 512. The outer cylinder 51 structure adopts a segmented assembly design, which is beneficial to the processing and manufacturing of the outer cylinder 51 and also facilitates the installation of the inner cylinder 52, the shaftless multi-column tooth structure 53, and the shaftless propeller blade 54.

[0046] The shaftless multi-column tooth structure 53 is located near the mixing chamber 5111, along the liquid flow direction of the inlet 5101, at the front end of the mixing chamber 5111, and is set on the inner wall of the second inner cavity 521. It is driven to rotate at high speed by the inner cylinder 52. The shaftless multi-column tooth structure 53 includes multiple spaced toothed support columns 531. Each toothed support column 531 is used to perform multiple rounds of gradient collisions, cutting and dissolving gas, and tearing and refining on the gas-liquid mixture from the mixing chamber 5111 during high-speed rotation, thereby generating a large number of microbubbles. The bottom 5311 of each toothed support 531 is fixed to the inner wall of the second inner cavity 521, and extends radially towards the center of the inner cylinder 52 to form the top 5312. Multiple toothed supports 531 can be arranged radially and axially along the circumferential surface of the inner wall of the second inner cavity 521 to form a "circumferential row + water flow row" array. There are radial gaps between the tops 5312 of each toothed support 531 towards the center of the inner cylinder 52. These gaps form the first water passage 5211 at the center of the second inner cavity 521. When the inner cylinder 52 rotates, the gas-liquid mixture in the mixing chamber 5111 is drawn into the shaftless multi-column toothed structure 53 area. Multiple spaced toothed supports 531 continuously perform multiple rounds of gradient collisions and cutting, so that the gas-liquid mixture is initially refined by mechanical shearing and tearing by the toothed supports 531. The pressurized environment of the second inner cavity 521 increases the initial solubility of the gas. As each toothed support 531 rotates during cutting, it forms a vortex at the first water passage 5211. This causes the gas-liquid mixture to continuously advance forward during the cutting process, undergoing turbulent compression and collision to achieve multiple breaks, resulting in a mixture with a large number of microbubbles at the end of the shaftless multi-column toothed structure 53. In this way, the gas-liquid mixture passes through each toothed support 531 sequentially during the high-speed rotation of the inner cylinder 52, undergoing multiple rounds of gradient collisions, cutting, tearing, and refinement along the radial and axial directions of the second inner cavity 521, and then flows forward through the vortex of the first water passage 5211, completing the process of gas-liquid mixing and dissolved gas forming microbubbles.

[0047] At least two shaftless propeller blades 54 are provided, disposed on the inner wall of the second inner cavity 521 and located on the side of the shaftless multi-column tooth structure 53 opposite to the inlet 5101 along the axial direction of the second inner cavity 521. They are located at the front end of the shaftless multi-column tooth structure 53 along the liquid flow direction of the inlet 5101 and are rotated together with the shaftless multi-column tooth structure 53 by the inner cylinder 52. The shaftless propeller blades 54 are radially arranged toward the center of the second inner cavity 521, with their roots 541 fixed to the inner wall of the second inner cavity 521 and their tips 542 facing the center of the second inner cavity 521. Each shaftless propeller blade 54 is tilted forward (away from the inlet 5101) at an angle of 10-20° to facilitate the forward propulsion of water flow. The tips 5312 of each blade 531 are radially aligned with the center of the second inner cavity 521, and there is a certain gap between them. The gap forms a second water passage 5212 at the center of the second inner cavity 521. The second water passage 5212 and the first water passage 5211 are on the same axis of the second inner cavity 521. The diameter of the second water passage 5212 is generally larger than that of the first water passage 5211. When the shaftless propeller blades 54 rotate at high speed under the drive of the inner cylinder 52, the spiral stirring effect of the shaftless propeller blades 54 generates a suction force that can create a strong negative pressure suction environment in the mixing chamber 5111. This can continuously draw external gas into the liquid phase, causing the liquid entering through the inlet 5101 and the gas entering through the air inlet 61 to be continuously drawn into the mixing chamber 5111. This also creates a pressurized environment in the second inner chamber 21, and the gas-liquid mixture forms a vortex turbulence that enters the region of the shaftless multi-column tooth structure 53. In other words, the liquid dynamics in the shaftless multi-column tooth structure 53 come from the vortex turbulence generated by the rotation of the shaftless propeller blades 54. Meanwhile, the microbubbles, which have been cut and torn by multiple rounds of gradient collisions in the shaftless multi-column tooth structure 53, can be further cut and broken by the entrainment and stirring of the shaftless propeller blades 54, forming a micro-nano carbon dioxide bubble mixture, which is then propelled forward (pushed). This mixture is driven along the second water passage 5212 into the bubble output chamber 5131 at the lower end of the shaftless propeller blades 54, and then discharged from the water outlet pipe 58 connected to the bottom of the outer cylinder 51.

[0048] When multiple shaftless aerators 5 are combined, such as Figure 1As shown, the first-stage shaftless aerator 5a and the second-stage shaftless aerator 5b are connected in series. A water suction pipe 59 is connected between the first-stage shaftless aerator 5a and the second-stage shaftless aerator 5b. The water suction pipe 59 is provided with multiple suction holes 591, which are used to draw the wastewater in the anoxic denitrification tank 1 into the second-stage shaftless aerator 5b. The wastewater is mixed with the micro-nano carbon dioxide bubble mixture output from the first-stage shaftless aerator 5a and enters the second-stage shaftless aerator 5b. It is then further drawn and propelled by the shaftless multi-column tooth structure 53 and the shaftless propeller blades 54, and subjected to multiple rounds of gradient collision cutting, tearing and refining to form a micro-nano carbon dioxide bubble mixture output that is smaller in size than that output from the first-stage shaftless aerator 5a.

[0049] In the structure of the shaftless aerator propeller 5 described above, wastewater from the inlet 5101 and carbon dioxide gas from the inlet pipe 61 are vertically mixed in the mixing chamber 5111. Then, negative pressure is generated by the shaftless propulsion action of the shaftless multi-tooth structure 3 and the shaftless propeller blades 54, achieving rapid intake and initial mixing of water and air. Simultaneously, the thrust generated by the rotation of the shaftless propeller blades 54 provides strong power for the collision and cutting of the toothed support pillars 41 of the shaftless multi-tooth structure 53. Thus, the gas-liquid mixture passes through the gradient cutting channel formed in the shaftless multi-tooth structure 53, undergoing intense collision, cutting, tearing, and refinement by each toothed support pillar 531, and is continuously squeezed by the first water passage 5211, generating a large number of microbubbles. Subsequently, the microbubbles are intensely stirred by the shaftless propeller blades 54, and then subjected to intense vortex compression in the second water passage 5212. This ensures smooth forward flow of the microbubbles while further improving the cutting efficiency, with a cutting frequency ≥10. 4 The speed of cutting and breaking down microbubbles to the micro-nano scale is achieved, producing stable bubbles with D10 of 50-100 micro-nano, D50 of 100-200 micro-nano, and D90 of 200-380 micro-nano (D10, D50, and D90 are terms for micro-nano bubble detection), which meet the standard requirements for high-quality micro-nano bubbles.

[0050] See Figure 3 In some embodiments of this application, each toothed support 531 is a trapezoidal cube structure with a quadrilateral base and an equilateral trapezoidal side projection, based on the inner wall of the second inner cavity 521; or a pyramidal structure with a polygonal base. This structure can effectively achieve the function of shaftless suction, cutting, and dissolving gas. Its edges and planes have a strong collision impact and cutting effect on the incoming gas-liquid mixture and bubbles. The orderly arrangement of multiple toothed supports 531s makes the bubbles progressively refined, and the structure is simple, easy to process, and has low manufacturing cost.

[0051] See also Figure 3In some embodiments of this application, each toothed support 531 may be arranged radially around the inner wall of the second inner cavity 521, at intervals around the circumference of the inner wall of the second inner cavity 521. That is, multiple toothed supports 531 are arranged at intervals around the same horizontal plane of the inner wall of the second inner cavity 521. At the same time, along the axial direction of the inner wall of the second inner cavity 521, the toothed supports 531 arranged in layers at intervals, with each layer of toothed supports 531 located on the same axial line of the inner wall of the second inner cavity 521. That is, each toothed support 531 is arranged in a consistent axial direction on the inner wall of the second inner cavity 521. In this way, the toothed supports 531 form a neat and uniform array on the inner wall of the second inner cavity 521, so that the gas-liquid mixture and bubbles are successively collided and cut by the next row of toothed supports 531 during the downward flow.

[0052] In some embodiments of this application, each toothed support 531 may also be arranged radially around the inner wall of the second inner cavity 521, at intervals around the circumference of the inner wall of the second inner cavity 521. That is, multiple toothed supports 531 are arranged at intervals around the same horizontal plane of the inner wall of the second inner cavity 521. At the same time, they are arranged in layers at intervals along the axial direction of the inner wall of the second inner cavity 521, and the toothed supports 531 in adjacent layers are axially staggered. In this arrangement, because the toothed supports 531 are axially staggered, the gas-liquid mixture and bubbles are cut more precisely and thoroughly during the downward flow process, and no bubble is missed.

[0053] In some embodiments of this application, the number of radial columns of each toothed strut 531 surrounding the second inner cavity 521 is preferably 4-8, and the number of axial rows along the second inner cavity 521 is preferably 5-10.

[0054] See also Figure 3 and Figure 4In some embodiments of this application, a magnetic sleeve 56 is provided around the outer wall of the inner cylinder 52, which can be glued and fixed to the outer wall of the inner cylinder 52, so that the magnetic sleeve 56 covers the outer wall of the inner cylinder 52. The magnetic sleeve 56 is made of magnetic material. At the same time, an inductor coil 55 is provided on the inner wall of the second cylinder 512 of the outer cylinder 51, which is connected to a power source. The inductor coil 55 has 12 to 16 poles and is fixed around the inner wall of the second cylinder 512. It is encapsulated with epoxy resin for waterproofing and is arranged around the outer ring of the magnetic sleeve 56, corresponding to the magnetic sleeve 56. A magnetic gap is left between the two. During operation, the second cylinder 512 is fixed, and the inductor coil 55 in the second cylinder 512 drives the magnetic sleeve 56 to drive the inner cylinder 52 to rotate. In this way, the magnetic sleeve 56 and the inductor coil 55 on the outer layer of the inner cylinder 52 form a magnetic levitation structure, so that the inner cylinder 52 is suspended in the first inner cavity 510 and rotates at high speed in the first inner cavity 510 under the magnetic drive of the inductor coil 55. This driving method has a simple structure and few components, which is conducive to the design of shaftless multi-column tooth structure 53. It provides layout space for each tooth support column 531. Moreover, the structure is simple and easy to operate. It does not require high-pressure equipment and has strong large-scale production capacity. While improving the cutting effect, it significantly reduces production costs and operating energy consumption.

[0055] See further Figure 3 Sealed bearings 57 are respectively provided on both sides of the inductor coil 55 along its axial direction. The outer ring of the sealed bearing 57 is fixed to the inner wall of the outer cylinder 51 (second cylinder 512), and the inner ring is fixed to the two outer ends of the inner cylinder 52 along its axial direction, rotating with the inner cylinder 52. The sealed bearings 57 can be used to position the inner cylinder 52 on the outer cylinder 51, and the rolling balls therein do not affect the rotation of the inner cylinder 52. The use of sealed bearings 57 can also effectively prevent water from entering the inductor coil 55 and the sealed bearings 57, thus protecting the inductor coil 55 and preventing water immersion from damaging or reducing the function of the inductor coil 55. This improves the stability of the inner cylinder 52, the shaftless multi-column tooth structure 53, and the shaftless propeller blades 54, while also protecting the rolling elements and raceways of the sealed bearings 57 and extending the service life of the sealed bearings 57.

[0056] In some embodiments of this application, the rotational speed of the inner cylinder 52 can be adjusted in the range of 5000-15000 r / min, and the power of the inductor coil 55 is 500W-1500W. When multiple shaftless aerators 5 are connected in series, different rotational speeds of the inner cylinder 52 and the power of the inductor coil 55 can be selected. Multi-stage synergy can achieve efficient preparation of ultrafine bubbles and high-concentration dissolved gas, improve dissolved oxygen mass transfer efficiency, make gas and liquid mix uniform, and make carbon dioxide bubbles less prone to breakage, finer and more stable, and can output ultrafine carbon dioxide bubble dissolved liquid stably for a long time.

[0057] See Figure 1In some embodiments of this application, a flow regulating valve 62 and a pressure reducing valve 63 are provided on the gas tank 6. By using the flow regulating valve 62 and the pressure reducing valve 63, the amount of carbon dioxide entering the shaftless aerator 5 and the inlet pressure can be controlled, so that the amount of carbon dioxide added is 10-20% of the inlet water volume. After multi-stage cutting and dissolving, 0.1-5μm micro-nano CO2 bubbles are generated, which meet the denitrification requirements.

[0058] See Figure 1 In some embodiments of this application, the bubble stabilizing liquid storage tank 7 is equipped with a liquid extraction pipe 72 and a liquid addition pump 73 with metering function, which is connected to the shaftless aerator 5 through the liquid addition pipe 74, which is conducive to the accurate delivery of the bubble stabilizing liquid.

[0059] The above embodiments shown in this application are only part of the preferred embodiments of this application and should not be construed as limiting this application. Any modifications, equivalent substitutions and improvements made by those skilled in the art without departing from the spirit of this application shall be within the protection scope of this application.

Claims

1. A high-nitrogen, high-hardness wastewater denitrification system based on micro / nano carbon dioxide bubbles, characterized in that, include: The electrobiological packing unit is suspended in the anoxic denitrification tank. At least one shaftless aerator is installed in the anoxic denitrification tank and located below the electrobiological packing unit. The shaftless aerator includes a shaftless multi-column tooth structure and shaftless propeller blades arranged axially in sequence and rotating together. The carbon dioxide gas introduced into the shaftless aerator and the wastewater drawn into the anoxic denitrification tank form a gas-liquid mixture in the shaftless aerator. After being subjected to multiple rounds of gradient collision, cutting, dissolving, tearing and refining by the shaftless multi-column tooth structure, the mixture is further stirred, broken and refined by the shaftless propeller blades, and finally formed into a micro-nano carbon dioxide bubble mixture before being pushed out. A gas tank, which stores carbon dioxide gas, is connected to an air inlet pipe, through which the carbon dioxide gas is introduced into the shaftless aerator. A bubble stabilizing liquid storage chamber stores bubble stabilizing liquid containing compound stabilizers. It is connected to an inlet pipe, through which the bubble stabilizing liquid in the bubble stabilizing liquid storage chamber is introduced into the shaftless aerator.

2. The high-nitrogen, high-hardness wastewater denitrification system based on micro / nano carbon dioxide bubbles according to claim 1, characterized in that, The compound stabilizer in the bubble stabilizing liquid contains the following mass percentages: polyethylene glycol 0.5-2%; sodium carboxymethyl cellulose 0.3-1%; AA / AMPS sulfonate organic copolymer 0.1-1%; and the balance is water.

3. The high-nitrogen, high-hardness wastewater denitrification system based on micro / nano carbon dioxide bubbles according to claim 1, characterized in that, The electrobiofiller unit includes a conductive cathode filler and a titanium metal anode support, with the conductive cathode filler suspended on the metal anode support.

4. The high-nitrogen, high-hardness wastewater denitrification system based on micro / nano carbon dioxide bubbles according to any one of claims 1-3, characterized in that, The shaftless aeration propeller also includes: An outer cylinder having a first inner cavity, with an inlet on one axial side of the outer cylinder communicating with the first inner cavity, wherein the outer cylinder of the first-stage shaftless aerator is radially connected to the air inlet pipe, so that carbon dioxide gas and wastewater entering the first inner cavity of the first-stage shaftless aerator vertically converge to form a gas-liquid mixture; An inner cylinder disposed within the first inner cavity and driven to rotate, the inner cylinder having a second inner cavity; The shaftless multi-column tooth structure is disposed on the inner wall of the second inner cavity and is driven by the inner cylinder to rotate at high speed. It is used to perform multiple rounds of gradient collision, cutting, dissolving, tearing and refining of the gas-liquid mixture in the first inner cavity to generate a large number of microbubbles. It includes multiple spaced toothed pillars, which are arranged in an array along the inner wall of the second inner cavity. The bottom of each toothed pillar is fixed to the inner wall of the second inner cavity and extends radially towards the center of the inner cylinder to form a top. The radial gap between the tops of each toothed pillar forms a first water passage at the center of the second inner cavity. At least two shaftless propeller blades are disposed on the inner wall of the second inner cavity and rotated by the inner cylinder. They are used to entrain the gas-liquid mixture to form a vortex turbulence and to further stir, cut and break the mixture with microbubbles after it has been cut by the shaftless multi-column tooth structure, further refining it into a micro-nano carbon dioxide bubble mixture and pushing it forward. The root of each shaftless propeller blade is fixed on the inner wall of the second inner cavity, and the tip faces the center of the second inner cavity. The radial gap between the tips of each shaftless propeller blade forms a second water passage at the center of the second inner cavity. The outer cylinder is also provided with a bubble output chamber for outputting the micro-nano carbon dioxide bubble mixture pushed out by the shaftless propeller blades.

5. The high-nitrogen, high-hardness wastewater denitrification system based on micro / nano carbon dioxide bubbles according to claim 4, characterized in that, Each of the toothed support pillars is a cubic structure with the inner sidewall of the second inner cavity as its base and roughly in the shape of an equilateral trapezoid; or a pyramidal structure with a polygonal base.

6. The high-nitrogen, high-hardness wastewater denitrification system based on micro / nano carbon dioxide bubbles according to claim 4, characterized in that, Each of the toothed supports is arranged radially around the inner wall of the second inner cavity at intervals, and is arranged in layers at intervals along the inner wall of the second inner cavity at axial intervals, with the toothed supports in each layer on the same axial line; or, each of the toothed supports is arranged radially around the inner wall of the second inner cavity at intervals, and is arranged in layers at intervals along the inner wall of the second inner cavity at axial intervals, with the toothed supports in adjacent layers being axially offset.

7. The high-nitrogen, high-hardness wastewater denitrification system based on micro / nano carbon dioxide bubbles according to claim 6, characterized in that, Each of the toothed struts has 4-8 columns radially surrounding the second inner cavity and 5-10 rows axially along the second inner cavity.

8. The high-nitrogen, high-hardness wastewater denitrification system based on micro / nano carbon dioxide bubbles according to claim 4, characterized in that, The outer wall of the inner cylinder is covered with a magnetic sleeve. An inductor coil connected to a power source is fixed around the inner wall of the outer cylinder and is arranged corresponding to the magnetic sleeve, so that the inner cylinder is suspended in the first inner cavity and rotates at high speed in the first inner cavity under the magnetic drive of the inductor coil.

9. The high-nitrogen, high-hardness wastewater denitrification system based on micro / nano carbon dioxide bubbles according to claim 8, characterized in that, Sealed bearings are provided at both ends of the inductor coil along its axial direction. The outer rings of the two sealed bearings are fixed to the inner wall of the outer cylinder, and the inner rings are fixed to the two outer ends of the inner cylinder along its axial direction, rotating with the inner cylinder.

10. The high-nitrogen, high-hardness wastewater denitrification system based on micro / nano carbon dioxide bubbles according to any one of claims 1-3, characterized in that, The gas tank is equipped with a flow regulating valve and a pressure reducing valve, and the bubble stabilizing liquid storage tank is equipped with a liquid adding pump.

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