Three-dimensional monolithic biochar column biofilm packing, method of making and wastewater treatment system

Abstract

The application discloses a three-dimensional charcoal column-shaped biofilm filler, a preparation method and a sewage treatment system, and relates to the technical field of water treatment and environmental engineering materials. The whole is a six-prism structure, comprising a first structure layer and a second structure layer; the first structure layer is an annular closed structure; the second structure layer is an annular closed structure and is located on the inner side of the first structure layer; the first structure layer and the second structure layer are divided into a plurality of grids by a connecting rib, and a plurality of short fin plates are arranged on the inner wall of the grid. The filler has a large specific surface area and good biofilm formation capacity, can effectively avoid internal blockage, and has more microporous structures and functional groups on the surface of the filler, can release some organic substances and nutrients, can not only optimize the community structure of denitrifying microorganisms, but also can improve the denitrifying enzyme activity and functional gene abundance, so that the surface microorganism's sewage treatment capacity is effectively enhanced.

Description

Technical Field

[0001] This invention belongs to the field of water treatment and environmental engineering materials technology, specifically a three-dimensional biochar columnar biofilm packing, its preparation method, and a wastewater treatment system. Background Technology

[0002] Nitrogen in water bodies is one of the main causes of eutrophication, and wastewater must undergo denitrification treatment before discharge. Wastewater denitrification is mainly achieved through biofilm processes, the core of which consists of two interrelated enzymatic reactions: nitrification and denitrification. In nitrification, oxygen oxidizes ammonia nitrogen to nitrate nitrogen under the catalysis of enzymes secreted by nitrifying bacteria. In denitrification, during the metabolism of denitrifying bacteria, carbon sources act as electron donors, and under the catalysis of their secreted enzymes, nitrate nitrogen is gradually reduced to nitrogen gas, which escapes from the water, thus achieving the purpose of wastewater denitrification.

[0003] If we can increase the number of microorganisms, and consequently the number of biological enzymes, the efficiency of both nitrification and denitrification can be improved, resulting in more thorough nitrogen removal from wastewater. The biomass of the biofilm process is closely related to the properties of the packing material.

[0004] Chinese patent CN106186358B discloses a biochar viscose fiber slow-release carbon source packing material. Using viscose fiber as a framework and loading 5-15% micron-sized biochar, it combines structural support with slow-release carbon source functions, solving the problem of traditional carbon sources being completely encapsulated and difficult to utilize. This packing material can provide a continuous carbon source during denitrification, improving nitrogen removal efficiency. However, its morphology is fibrous or flocculent, lacking a clear geometric configuration, making it prone to entanglement or loss under water flow impact, which is detrimental to stable operation in fixed-bed or moving-bed reactors. Furthermore, its three-dimensional structure does not form a continuous flow channel network, limiting its cutting and dispersion effect on the gas-liquid two phases, potentially affecting aeration efficiency and biofilm renewal rate.

[0005] In summary, existing biochar packing materials primarily focus on improving material composition or porosity in their structural design, but there is room for improvement in three-dimensional geometry, hydrodynamic adaptability, and guidance of biofilm spatial distribution. Therefore, there is an urgent need to develop a three-dimensional biochar columnar biofilm packing material with a clearly defined columnar structure and a coordinated design of internal through-channels and external open interfaces to optimize mass transfer efficiency, enhance biofilm stability, and improve denitrification performance. Summary of the Invention

[0006] To overcome the shortcomings of the prior art described above, and considering at least one of the aforementioned technical problems, this invention aims to solve the problems of insufficient specific surface area, poor biofilm attachment performance, and easy internal clogging in existing biofilm packings by constructing a columnar geometric configuration with a double-layered annular structure, internal through-channels, and external microporous surface working synergistically, and by incorporating biochar and tourmaline functional components. The specific technical solution is as follows: A three-dimensional biochar columnar biofilm packing material includes a first structural layer, a second structural layer, a connecting portion, and an extension portion. The first structural layer is an annular closed structure. The second structural layer is an annular closed structure and is located inside the first structural layer. A first carrier channel is formed between the second structural layer and the first structural layer, and a second carrier channel is formed on the side of the second structural layer facing away from the first structural layer. The connecting portion connects the first structural layer and the second structural layer and divides the annular region between the first structural layer and the second structural layer into several grids. The extension portion is distributed on the inner wall surface of the first carrier channel, the inner wall surface of the second carrier channel, and the surface of the connecting portion.

[0007] In some embodiments of this disclosure, the surfaces of the first structural layer and the second structural layer are distributed with microporous structures with pore sizes ranging from 0.1 micrometers to 10 micrometers.

[0008] In some embodiments of this disclosure, both the first structural layer and the second structural layer contain biochar, the biochar accounting for 20% to 25% of the total mass of the filler, the biochar being uniformly dispersed in a thermoplastic matrix and forming the microporous structure during the molding process.

[0009] In some embodiments of this disclosure, the first structural layer and the second structural layer include an acid-base adjustment unit composed of tourmaline particles with a particle size of 1 micrometer to 50 micrometers and a mass accounting for 5% to 8% of the total mass of the filler.

[0010] In some embodiments of this disclosure, the filler further includes a thermoplastic material selected from at least one of polyethylene, polypropylene, or polystyrene, which accounts for 60% to 75% of the total mass of the filler.

[0011] In some embodiments of this disclosure, the length of the extension is 1 mm to 8 mm, and the extension protrudes outward in a direction perpendicular to the wall surface; the connecting part is a connecting rib, the number of the connecting ribs is 3 to 12, and they are evenly distributed in the circumferential direction; the extension is a short fin plate, and the short fin plates are arranged in an array on the inner wall of each channel, with a spacing of 0.5 mm to 3 mm between adjacent short fin plates.

[0012] In some embodiments of this disclosure, the cross-sections of the first structural layer and the second structural layer are both polygonal structures, and the number of sides of the polygons is 4 to 8; the monomer shape of the three-dimensional biochar columnar biofilm packing is columnar, with an inscribed circle diameter of 6 mm to 30 mm and a height of 20 mm to 50 mm.

[0013] In some embodiments of this disclosure, the filler comprises, by mass percentage: 70% to 78% polyethylene, 20% to 25% biochar, 5% to 8% tourmaline, 3% to 6% polyvinylpyrrolidone, and 3% to 6% silica.

[0014] In some embodiments of this disclosure, the first carrier channel is a trapezoidal or polygonal cavity formed by the inner wall of the first structural layer, the outer wall of the second structural layer, and a plurality of connecting ribs; the second carrier channel is a central hexagonal cavity formed by the inner wall of the second structural layer; each channel extends along the packing axis to form a continuous flow channel.

[0015] In some embodiments of this disclosure, a method for preparing a three-dimensional biochar columnar biofilm packing material is characterized by comprising the following steps: S10: Add thermoplastic plastic granules, biochar powder, tourmaline powder, polyvinylpyrrolidone and silica to a high-speed mixer according to the specified ratio, and mix for 8 to 15 minutes at a speed of 800 to 1500 rpm to obtain a uniform mixture. S20: The mixture is fed into a twin-screw extruder and melt-blended at a temperature of 170°C to 200°C and a screw speed of 100 rpm to 200 rpm, then extruded and granulated to obtain a composite masterbatch. S30: The composite masterbatch is dried to a moisture content of less than 0.5%, and then fed into the hopper of an injection molding machine. It is then injection molded using a special cylindrical mold. The injection temperature is set to 180 degrees Celsius to 210 degrees Celsius, the injection pressure is 60 MPa to 90 MPa, the holding time is 10 seconds to 20 seconds, and the cooling time is 20 seconds to 40 seconds. S40: Rinse the injection-molded filler with deionized water three or more times to remove residual additives on the surface, then place it in a 70°C oven for 60 minutes for heat treatment, then wash it with deionized water and air dry it naturally to obtain the three-dimensional biochar column biofilm filler.

[0016] In some embodiments of this disclosure, a wastewater treatment system is characterized in that the wastewater treatment system includes the aforementioned three-dimensional biochar columnar biofilm packing.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The hexagonal prism structured biochar biofilm packing of the present invention contains biochar, wherein biochar and tourmaline can serve as conductive mediators for microbial metabolic reactions, and the redox functional groups on the biochar enable it to store and transfer electrons, thereby enhancing the decomposition ability of extracellular enzymes and effectively enhancing the sewage treatment capacity of microorganisms.

[0018] 2. The hexagonal prism structure of the biochar biofilm packing material of the present invention not only increases the overall specific surface area of ​​the packing material, but also reduces the contact angle of the packing material surface due to the structure and the short wings on it, thereby increasing the hydrophilicity of the packing material and making it easier for microorganisms to attach and grow.

[0019] 3. The acid-base regulating unit in the hexagonal prism-structured biochar biofilm packing of this invention has acid-base buffering capacity, which can regulate the pH value of the water to a certain extent. Stable water pH helps maintain the physiological activities of aquatic organisms and avoids the impact of pH fluctuations on microbial activity. Tourmaline can effectively reduce the impact of heavy metal ions in wastewater on microorganisms.

[0020] In summary, this invention constructs a three-dimensional biochar columnar biofilm packing material with high specific surface area, excellent biofilm attachment performance, anti-clogging ability, and metabolism-promoting function through hexagonal prism structure design, microporous surface construction, functional component composite and precise molding process. It solves the key problems existing in the prior art from the three dimensions of structure, material and function. Attached Figure Description

[0021] Figure 1 This is a schematic cross-sectional view of a three-dimensional biochar columnar biofilm packing material according to the present invention. Figure 2 This is a surface electron microscope image (left: 2µm, right: 20µm) of a three-dimensional biochar columnar biofilm packing material of the present invention. Figure 3 The images show the surface electron microscope images of conventional biofilm packing materials (left: 2µm, right: 20µm).

[0022] Explanation of reference numerals in the attached figures: 1. First structural layer; 2. Second structural layer; 3. Connecting part; 4. Extension part. Detailed Implementation

[0023] To better understand the purpose, structure, and function of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below.

[0024] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The terms "comprising" and "having" and any variations thereof, as used herein, are open-ended and intended to cover non-exclusive inclusion. Example

[0025] like Figure 1 As shown, a three-dimensional biochar columnar biofilm packing material includes a first structural layer 1, a second structural layer 2, connecting ribs, and short fins. Both the first structural layer 1 and the second structural layer 2 are hexagonal prism structures; the second structural layer 2 is located inside the first structural layer 1, a first carrier channel is formed between the second structural layer 2 and the first structural layer 1, and a second carrier channel is formed on the side of the second structural layer 2 facing away from the first structural layer 1. The first structural layer 1 and the second structural layer 2 are connected by connecting ribs and divided into several trapezoidal grids; the second carrier channel in the middle of the second structural layer 2 is a hexagonal grid, and several short fins are provided on the inner sidewalls of the hexagonal grid and the trapezoidal grid.

[0026] Both the first structural layer 1 and the second structural layer 2 include straw biochar, and the straw biochar forms the microporous structure in the first structural layer 1 and the second structural layer 2.

[0027] The first structural layer 1 and the second structural layer 2 include tourmaline, which forms the acid-base regulating unit.

[0028] The hexagonal prism structure of the biochar biofilm packing material can be flexibly adjusted in terms of side length and height according to the tank structure.

[0029] The hexagonal prism structure of the biochar biofilm packing has an inscribed circle diameter of 6-30 mm, a length of 20-50 mm, and a thickness of 2-5 mm. Among them, the biochar biofilm packing with a length of about 20 mm can provide a larger specific surface area to facilitate the attachment and biofilm formation of microorganisms.

[0030] The specific surface area of ​​the hexagonal prism structured biochar biofilm packing is controlled to be 100-300 m². 2 / m 3 .

[0031] The hexagonal prism structured biochar biofilm filler is composed of polyethylene, biochar, tourmaline, polyvinylpyrrolidone, and silicon dioxide.

[0032] The biochar content in the hexagonal prism structured biochar biofilm filler is as high as 0%-25%.

[0033] In this embodiment, both the first structural layer 1 and the second structural layer 2 have hexagonal cross-sections, and hexagons achieve the most ideal effect compared to other shapes.

[0034] The effect of the hexagon is illustrated by comparing quadrilaterals and circles with the hexagon in this embodiment.

[0035] Compared to quadrilaterals, prisms with hexagonal cross-sections have a larger specific surface area for the same inscribed circle radius. Compared to circles, the connection between the outer and inner hexagons creates an acute angle within the filler, enhancing hydrophilicity and allowing microorganisms to adhere more easily.

[0036] The biofilm packing material used in this embodiment is all non-toxic. Combined with its structure, the packing material has a large specific surface area and good biofilm formation ability, which can effectively avoid internal clogging. In addition, the surface of the packing material also has a large number of microporous structures and functional groups, which can release some organic matter and nutrients. This not only optimizes the community structure of denitrifying microorganisms, but also enhances the activity of denitrifying enzymes and the abundance of functional genes, thereby effectively enhancing the ability of surface microorganisms to treat wastewater.

[0037] The preparation method of the three-dimensional biochar columnar biofilm packing in this embodiment is as follows: Raw material usage: In this embodiment, the basic raw material amounts (by mass percentage) used in the preparation of the biofilm packing are as follows: Preparation method: (1) Place all the basic raw materials in the filler into a high-speed mixer according to the above mass ratio and stir for 10 minutes to make them fully and evenly mixed; (2) The density of the mixed raw materials was measured to be 0.959 g / cm³. 3 ; (3) The mixed raw materials after the above treatment are placed in the hopper of an injection molding machine and injection molded using a specific cylindrical biofilm filler mold in a two-stage injection molding method. The injection temperature is set to 180-210℃. After injection molding, the material is repeatedly washed with secondary water and placed in a 70℃ oven for heat treatment. After one hour, it is taken out and thoroughly washed with secondary water again. The resulting biofilm filler is a hexagonal prism with a height of 20mm and an inscribed circle diameter of 14mm.

[0038] Effect test: This three-dimensional biochar columnar biofilm packing material was applied to the primary sedimentation tank of a wastewater treatment plant. The tested wastewater had a pH of 8, COD of 300 mg / L, total nitrogen of 45 mgN / L, and nitrate nitrogen of 32 mgN / L. Activated sludge, obtained from a wastewater treatment plant, was cultured to stably treat the primary sedimentation tank wastewater. Both conventional biofilm packing material and the three-dimensional biochar columnar biofilm packing material, after biofilm formation, were added to the wastewater, with a packing fill rate of 30% and a heat transfer time (HRT) of 8 hours. After three days of continuous treatment, the measurement results are as follows: The experimental data above show that, compared with ordinary suspended packing materials, the product in this embodiment significantly improves the removal rates of COD, total nitrogen, and nitrate nitrogen in industrial wastewater. In a fixed-bed biofilm reactor, this product provides the necessary nutrients for microorganisms and forms a biofilm system with superior treatment performance. This results in increased microbial attachment efficiency, stronger metabolic activity of the microorganisms, and a significantly improved removal effect compared to ordinary biofilm packing materials.

[0039] In one specific embodiment of the present invention, the surfaces of both the first structural layer 1 and the second structural layer 2 are provided with microporous structures, the pore size of which ranges from 0.1 micrometers to 10 micrometers. These microporous structures are formed during injection molding by interfacial voids created by biochar particles in the thermoplastic matrix and residual pyrolysis channels, with a distribution density of 50 to 200 pores per square millimeter.

[0040] In one specific embodiment of the present invention, both the first structural layer 1 and the second structural layer 2 are composed of a thermoplastic matrix composite functional components, wherein the biochar accounts for 20% to 25% of the total mass of the filler, the tourmaline particles account for 5% to 8% of the total mass of the filler, and the thermoplastic is selected from at least one of polyethylene, polypropylene, or polystyrene, accounting for 60% to 75% of its mass. Furthermore, the formulation also includes 3% to 6% polyvinylpyrrolidone as a dispersant and interfacial compatibilizer, and 3% to 6% silica as an inorganic filler to adjust density and enhance surface roughness.

[0041] In one specific embodiment of the present invention, the biochar is derived from at least one of straw, rice husks, or sawdust, and is obtained by pyrolysis at 400°C to 700°C. Its specific surface area is not less than 200 square meters per gram, and its particle size is controlled within the range of 10 micrometers to 100 micrometers. The surface contains redox functional groups such as carboxyl, hydroxyl, and quinone groups. The tourmaline is natural black tourmaline, which is ball-milled and passed through a 200-mesh sieve. Its particle size is 1 micrometer to 50 micrometers, and its zeta potential is maintained between -30 mV and -50 mV within the pH range of 6 to 9.

[0042] In one specific embodiment of the present invention, the thickness of the first structural layer 1 and the second structural layer 2 are each independently 2 mm to 5 mm. The connecting part 3 is a connecting rib structure, with 3 to 12 ribs evenly distributed circumferentially, and its cross-section is rectangular or trapezoidal, with a width of 0.5 mm to 2 mm and a thickness consistent with the first structural layer 1 or the second structural layer 2. The extension part 4 is a short fin structure, protruding outward in a direction perpendicular to the wall surface, with a length of 1 mm to 8 mm. The distribution density on the inner wall of the first carrier channel 5 is 8 to 20 per square centimeter, and the distribution density on the inner wall of the second carrier channel 6 is 10 to 25 per square centimeter. The spacing between adjacent short fins is 0.5 mm to 3 mm.

[0043] In one specific embodiment of the present invention, the cross-sections of the first structural layer 1 and the second structural layer 2 are both polygonal structures with 4 to 8 sides; preferably, the polygons are hexagonal, that is, both the first structural layer 1 and the second structural layer 2 are hexagonal prism structures. In this case, the first carrier channel 5 is a trapezoidal or polygonal cavity formed by the inner wall of the first structural layer 1, the outer wall of the second structural layer 2, and multiple connecting ribs, and the second carrier channel 6 is a central hexagonal cavity formed by the inner wall of the second structural layer 2; each channel extends along the packing axis, forming a continuous flow channel.

[0044] In one specific embodiment of the present invention, the packing monomer is cylindrical in shape, with an inscribed circle diameter of 6 mm to 30 mm and a height of 20 mm to 50 mm. When the height is approximately 20 mm, the specific surface area of ​​the packing per unit volume is 100 m² / m³ to 300 m² / m³. The contact angle of the packing surface is less than 60 degrees, and its hydrophilicity is achieved through the microscale acute-angle structure formed at the hexagonal corners and the capillary effect induced by the short fins.

[0045] This invention also provides a method for preparing the above-mentioned three-dimensional biochar columnar biofilm packing, specifically including the following steps: S10: Add thermoplastic granules, biochar powder, tourmaline powder, polyvinylpyrrolidone and silica to a high-speed mixer according to the specified ratio, and mix for 8 to 15 minutes at a speed of 800 to 1500 rpm to obtain a uniform mixture; wherein the particle size of biochar powder is 10 to 100 micrometers and the particle size of tourmaline powder is 1 to 50 micrometers.

[0046] S20: The mixture is fed into a twin-screw extruder and melt-blended under conditions of 170°C to 200°C and screw speed of 100 rpm to 200 rpm, then extruded and granulated to obtain composite masterbatch; the temperature zone of the twin-screw extruder is set to five sections, namely 160°C, 175°C, 190°C, 195°C and 185°C.

[0047] S30: The composite masterbatch is dried to a moisture content of less than 0.5%, and then fed into the hopper of an injection molding machine. It is injection molded using a special cylindrical mold. The injection temperature is set to 180 degrees Celsius to 210 degrees Celsius, the injection pressure is 60 MPa to 90 MPa, the holding time is 10 seconds to 20 seconds, and the cooling time is 20 seconds to 40 seconds. The cavity of the special cylindrical mold is a hexagonal prism structure. The inner cavity size corresponds to the inscribed circle diameter of the filler, which is 14 mm and the height is 20 mm. The mold surface is polished and the roughness Ra is less than 0.8 micrometers.

[0048] S40: After injection molding, the filler is rinsed repeatedly with deionized water more than three times to remove residual additives on the surface. Then, it is placed in a 70°C oven for heat treatment for 60 minutes, then rinsed with deionized water and air-dried to obtain the three-dimensional biochar columnar biofilm filler. The heat treatment process causes partial rearrangement of the polyethylene molecular chains, stabilizes the microporous structure, and promotes the formation of hydrogen bond networks between the functional groups on the biochar surface and polyvinylpyrrolidone, thereby enhancing the overall structural stability of the filler.

[0049] The filler prepared by the above method has a density of 0.92 g / cm³ to 0.98 g / cm³, a compressive strength greater than 15 MPa, and an abrasion rate of less than 2% per thousand hours.

[0050] This invention also provides the application of the above-mentioned three-dimensional biochar columnar biofilm packing material in wastewater treatment, specifically in fixed-bed or moving-bed biofilm reactors. In the reactor, the packing material filling rate is 20% to 40%, and the hydraulic retention time is 6 to 12 hours. During the biofilm formation stage, activated sludge is inoculated at a concentration of 3000 mg / L to 5000 mg / L and cultured for 5 to 7 days under conditions of dissolved oxygen concentration of 2 mg / L to 4 mg / L and temperature of 20°C to 30°C to form a stable biofilm.

[0051] During operation, the biochar on the packing surface releases trace amounts of organic acids and phenolic substances, with concentrations maintained between 0.5 mg / L and 2 mg / L; tourmaline continuously releases negative ions and far-infrared radiation. The edges of the hexagonal structure form an angle with the water flow direction, causing vortices and shearing as the water flows through the first carrier channel 5 and the second carrier channel 6; the presence of short fins further disturbs the boundary layer. During operation, the biofilm thickness within the first carrier channel 5 and the second carrier channel 6 remains between 50 μm and 150 μm, with no significant blockage within the channels, and the water pressure drop remains stable between 0.1 kPa / m and 0.3 kPa / m.

[0052] It is understood that the above description is only for illustrating specific implementation methods of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered within the scope of disclosure of this application.

Claims

1. A three-dimensional biochar columnar biofilm packing material, characterized in that, It includes a first structural layer, a second structural layer, a connecting portion, and an extension portion; the first structural layer is an annular closed structure; the second structural layer is an annular closed structure and is located inside the first structural layer; a first carrier channel is formed between the second structural layer and the first structural layer, and a second carrier channel is formed on the side of the second structural layer facing away from the first structural layer; the connecting portion connects the first structural layer and the second structural layer, and divides the annular area between the first structural layer and the second structural layer into several grids; the extension portion is distributed on the inner wall surface of the first carrier channel, the inner wall surface of the second carrier channel, and the surface of the connecting portion.

2. The three-dimensional biochar columnar biofilm packing material according to claim 1, characterized in that, The surfaces of the first and second structural layers are distributed with microporous structures with pore sizes ranging from 0.1 micrometers to 10 micrometers.

3. The three-dimensional biochar columnar biofilm packing material according to claim 1, characterized in that, Both the first structural layer and the second structural layer contain biochar, the biochar accounting for 20% to 25% of the total mass of the filler, the biochar being uniformly dispersed in a thermoplastic matrix and forming the microporous structure during the molding process.

4. The three-dimensional biochar columnar biofilm packing material according to claim 1, characterized in that, The first structural layer and the second structural layer include an acid-base adjustment unit, which is composed of tourmaline particles with a particle size of 1 micrometer to 50 micrometers and a mass accounting for 5% to 8% of the total mass of the filler.

5. The three-dimensional biochar columnar biofilm packing material according to claim 1, characterized in that, The filler also includes a thermoplastic material selected from at least one of polyethylene, polypropylene, or polystyrene, which accounts for 60% to 75% of the total mass of the filler.

6. The three-dimensional biochar columnar biofilm packing material according to claim 1, characterized in that, The extension portion has a length of 1 mm to 8 mm and protrudes outward in a direction perpendicular to the wall surface; the connecting portion is a connecting rib, the number of which is 3 to 12, and they are evenly distributed circumferentially; the extension portion is a short fin plate, which is arranged in an array on the inner wall of each channel, and the spacing between adjacent short fin plates is 0.5 mm to 3 mm.

7. The three-dimensional biochar columnar biofilm packing material according to claim 1, characterized in that, Both the first and second structural layers have polygonal cross-sections, with the polygons having 4 to 8 sides; the three-dimensional biochar columnar biofilm packing has a columnar shape with an inscribed circle diameter of 6 to 30 mm and a height of 20 to 50 mm.

8. The three-dimensional biochar columnar biofilm packing material according to claim 1, characterized in that, The filler comprises, by mass percentage: 70% to 78% polyethylene, 20% to 25% biochar, 5% to 8% tourmaline, 3% to 6% polyvinylpyrrolidone, and 3% to 6% silica.

9. The three-dimensional biochar columnar biofilm packing material according to claim 1, characterized in that, The first carrier channel is a trapezoidal or polygonal cavity formed by the inner wall of the first structural layer, the outer wall of the second structural layer, and multiple connecting ribs; the second carrier channel is a central hexagonal cavity formed by the inner wall of the second structural layer; each channel is axially connected along the packing material to form a continuous flow channel.

10. A method for preparing a three-dimensional biochar columnar biofilm packing material as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S10: Add thermoplastic plastic granules, biochar powder, tourmaline powder, polyvinylpyrrolidone and silica to a high-speed mixer according to the specified ratio, and mix for 8 to 15 minutes at a speed of 800 to 1500 rpm to obtain a uniform mixture. S20: The mixture is fed into a twin-screw extruder and melt-blended at a temperature of 170°C to 200°C and a screw speed of 100 rpm to 200 rpm, then extruded and granulated to obtain a composite masterbatch. S30: The composite masterbatch is dried to a moisture content of less than 0.5%, and then fed into the hopper of an injection molding machine. It is then injection molded using a special cylindrical mold. The injection temperature is set to 180 degrees Celsius to 210 degrees Celsius, the injection pressure is 60 MPa to 90 MPa, the holding time is 10 seconds to 20 seconds, and the cooling time is 20 seconds to 40 seconds. S40: Rinse the injection-molded filler with deionized water three or more times to remove residual additives on the surface, then place it in a 70°C oven for 60 minutes for heat treatment, then wash it with deionized water and air dry it naturally to obtain the three-dimensional biochar column biofilm filler.

11. A wastewater treatment system, characterized in that, The wastewater treatment system includes the three-dimensional biochar columnar biofilm packing material as described in any one of claims 1 to 9.

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