Biological composite carbon source, preparation method and application thereof in sewage treatment

Abstract

The application discloses a biological composite carbon source, a preparation method thereof and application of the biological composite carbon source in sewage treatment, and the biological composite carbon source is obtained by mixing and extruding modified corncob powder, polybutylene adipate terephthalate, high-density polyethylene, polyvinyl alcohol, ethylene bis-stearamide and starch; the modified corncob powder is obtained by subjecting corncob powder to enzymolysis treatment in a composite enzyme composed of laccase and hemicellulase; and each component is formed into a micro composite structure through melt blending, so that the unification of the gradient release of a fast carbon source (polyvinyl alcohol / starch), a medium carbon source (modified corncob powder) and a long-acting carbon source (polybutylene adipate terephthalate), high mechanical strength and good processability is realized; and the final product has the comprehensive advantages of high denitrification efficiency, a long action period and high structural stability, and is efficient, long-acting, safe and stable.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and in particular to a biological composite carbon source, its preparation method, and its application in wastewater treatment. Background Technology

[0002] With increasingly stringent environmental protection requirements, advanced denitrification of wastewater has become a core task in the water treatment field. Biological denitrification is a key process for removing nitrate nitrogen from water, and its process relies on heterotrophic denitrifying bacteria utilizing organic carbon sources as electron donors. Therefore, the addition of external carbon sources is a crucial step in ensuring efficient and stable denitrification operation.

[0003] Currently, commonly used external carbon sources are mainly divided into two categories: liquid chemical carbon sources and solid biomass carbon sources.

[0004] Liquid carbon sources, such as methanol and sodium acetate, can be rapidly utilized by microorganisms, but they are inherently flammable, explosive, or toxic, posing safety risks during storage and transportation. Furthermore, their dosage requires precise control based on fluctuations in influent water quality, making operation complex. Overdosing can lead to excessive COD in the effluent, while underdosing can reduce denitrification efficiency, making operation and management difficult. In addition, some liquid carbon sources are expensive, and their metabolic byproducts may cause secondary pollution to the effluent.

[0005] Solid biomass carbon sources, such as corn cobs and straw, have attracted attention due to their wide availability and low cost. However, the dense structure of natural biomass materials (rich in lignin, cellulose, and hemicellulose) results in a slow and uncontrollable release of carbon sources in water, failing to meet the needs of rapid activation and stable metabolism of denitrifying bacteria, leading to low nitrogen removal efficiency. Furthermore, these materials have poor mechanical strength and are prone to breakage and loss under long-term hydraulic erosion and microbial action, not only clogging pipes but also shortening the carbon source release cycle, requiring frequent replenishment and increasing operation and maintenance costs.

[0006] In summary, existing technologies for liquid carbon sources face challenges such as high safety risks, difficulty in dosing control, and susceptibility to secondary pollution; while solid biomass carbon sources suffer from low denitrification efficiency, uncontrollable carbon release, poor mechanical strength, and susceptibility to breakage and loss. Therefore, developing a novel composite carbon source that combines high-efficiency denitrification performance, long-term stable carbon release, and high mechanical strength has become a pressing technical challenge in this field. Summary of the Invention

[0007] To address the technical problems of low nitrogen removal efficiency, uncontrollable carbon release, poor mechanical strength, and easy breakage and loss of solid biomass carbon sources, this application provides a biocomposite carbon source, its preparation method, and its application in wastewater treatment.

[0008] The first inventive objective of this invention is achieved through the following technical solution: A bio-composite carbon source is obtained by mixing and extruding modified corn cob powder, polybutylene adipate terephthalate, high-density polyethylene, polyvinyl alcohol, ethylene bis-stearamide, and starch. The modified corn cob powder is obtained by enzymatic hydrolysis of corn cob powder using a complex enzyme consisting of laccase and hemicellulase.

[0009] By adopting the above technical solution, this application provides a bio-composite carbon source formed by melt extrusion of modified corn cob powder, polybutylene adipate terephthalate, polyvinyl alcohol, starch, high-density polyethylene and ethylene bis-stearamide, which has a cascade carbon release function. Polyvinyl alcohol and starch, as short-term easily degradable components, rapidly dissolve and release small molecule organic matter in the initial stage of addition, quickly activating the denitrifying bacteria and enabling the biological denitrification system to start up quickly. High-density polyethylene forms a reinforcing network through molecular chain entanglement, which improves the mechanical strength and wear resistance of the biocomposite carbon source, ensuring that it maintains its structural integrity for a long time under sewage flushing, and can provide a stable carrier for microbial films. Ethylene bis-stearamide, as a lubricant, effectively reduces the viscosity of each component during melt blending, improves the flowability of extrusion processing, and ensures the uniformity and density of product molding. The key component modified corn cob powder is enzymatically modified by a combination of laccase and hemicellulase. Based on the composition of corn cob powder, the combination enzyme synergistically constructs a "lignin preferential degradation" mechanism during enzymatic modification. After laccase destroys the cross-linked structure of lignin phenolic units, hemicellulase rapidly decomposes the exposed hemicellulose network. Under the dual action, the specific surface area and porosity of corn cob powder are significantly increased, thereby maximizing the bioavailability of corn cob and the directional release of bioavailable carbon components in corn cob. A high-porosity carrier structure is constructed to enhance microbial attachment and provide a stable carbon release channel for subsequent composite carbon sources. This overcomes the defects of its original dense structure and slow carbon release, and provides a core slow-release carbon pool and biofilm growth interface for composite carbon sources. Polybutylene adipate terephthalate (PET) serves as a long-lasting, slow-release carbon source. In the aquatic environment, it achieves a long-term, continuous release of carbon through the slow, non-biological hydrolysis and microbial degradation of its ester bonds. This ensures that the denitrification system has a stable and continuous electron donor during long-term operation, compensating for the potential decrease in denitrification efficiency after the rapid depletion of the carbon source. Modified corn cob powder and polybutylene adipate terephthalate constitute a dual long-term carbon supply system of "bio-matrix slow release" and "synthetic polymer slow release"—the two have different degradation mechanisms (enzymatic / hydrolysis and microbial degradation), complementary release kinetics, and combined with the rapid release of polyvinyl alcohol / starch, forming a tiered carbon release curve that covers the entire denitrification process with rapid start-up, efficient nitrogen removal, and stable maintenance. This synergistic mechanism enables controllable carbon release rate and cycle, increasing the system's nitrogen removal efficiency to over 96%, and avoiding the phenomenon of "burst release" or "starvation" of a single carbon source. Traditional single carbon sources (such as methanol) or unmodified biomass carbon sources cannot achieve this controllable and long-term carbon release mode.

[0010] Thus, the components are melt-blended to form a micro-composite structure, achieving a cascade release of "rapid carbon source (polyvinyl alcohol / starch) - medium-efficiency carbon source (modified corn cob powder) - long-lasting carbon source (polybutylene terephthalate)" while maintaining high mechanical strength and good processability. The final product has the comprehensive advantages of high denitrification efficiency, long working cycle, and high structural stability, solving the technical problems of high safety risks and difficult addition control of traditional liquid carbon sources, as well as low denitrification efficiency, uncontrollable carbon release, and easy breakage and loss of solid biomass carbon sources. This results in a composite solid carbon source that is efficient, long-lasting, safe, and stable.

[0011] Optionally, the preparation method of the modified corn cob powder includes the following steps: Add corn cob powder and compound enzyme to water and stir continuously to carry out enzymatic hydrolysis; After enzymatic hydrolysis, the corn cob powder is washed and dried to obtain modified corn cob powder. The enzymatic hydrolysis time is 50-90 min; The enzymatic hydrolysis temperature is 10-25℃; The pH of the enzymatic hydrolysis environment is 6.5-7.5.

[0012] By adopting the above technical solution, the modified corn cob powder has a better effect and better buffering stability for the carbon cascade release of biocomposite carbon sources.

[0013] Optionally, the enzyme activity of the laccase is 80,000-120,000 U / g.

[0014] By adopting the above technical solution, the lignin degradation rate is high, and the processing time can be significantly shortened compared with the low enzyme activity system. It balances the degradation efficiency and raw material loss control, enabling the modified corn cob powder to achieve both high microbial loading rate and long-term carbon release in the composite carbon source.

[0015] Optionally, the enzyme activity of the hemicellulase is 40,000-60,000 U / g.

[0016] By adopting the above technical solutions, the enzyme activity threshold is optimized to balance enzymatic hydrolysis efficiency and cost, ensuring efficient hydrolysis of hemicellulose. Compared with low enzyme activity systems, the carbon release is significantly increased, while avoiding the collapse of the raw material structure caused by excessive hydrolysis. The specific enzyme activity, combined with neutral pH and suitable temperature conditions, maximizes the retention of the cellulose skeleton while reducing energy consumption, so that the modified corn cob powder has both high bioavailability and mechanical support function in the composite carbon source.

[0017] Optionally, the corn cob powder has a particle size of 20-100 mesh.

[0018] By adopting the above technical solutions, the particle size of corn cob powder is controlled at 20-100 mesh, balancing particle porosity and mechanical strength. This meets the flowability requirements of the extrusion process and avoids abnormal increases in screw torque caused by fine powder. Furthermore, by retaining the fragmentation scale of the natural tubular structure of corn cob, the microporous structure formed by enzymatic modification can effectively support denitrifying bacteria. During twin-screw extrusion, the modified corn cob powder forms a uniform and stable porous framework structure, providing a physical carrier basis for subsequent cascade carbon release. This avoids the problem of a sharp increase in viscosity and a decrease in flowability of the melt blend material caused by excessively fine powder. At the same time, it prevents excessively coarse particles from reducing the effective attachment interface for microorganisms due to insufficient specific surface area. This optimizes the processing performance and bioavailability of the biocomposite carbon source, ensuring that the extruded product has both high mechanical stability and microbial affinity, and simultaneously improving the structural stability of the carbon source product under hydraulic impact and the efficiency of biofilm formation.

[0019] Optionally, the average molecular weight of the polybutylene adipate terephthalate is 60,000-80,000.

[0020] By adopting the above technical solution, polybutylene adipate terephthalate with a specific average molecular weight range forms a moderately entangled molecular chain network during melt blending. The molecular chain entanglement density is optimized to form a semi-crystalline-amorphous alternating structure, which not only ensures that the melt viscosity is within a better processing window, but also achieves gradient control of carbon release rate through selective hydrolysis of β-ester bonds, thus simultaneously solving the problems of insufficient mechanical strength and carbon release inhibition of traditional polymer carbon sources. When the average molecular weight is below 60,000, insufficient chain entanglement leads to a decrease in the product's shear strength; when it is above 80,000, the increased rigidity of the molecular chain inhibits hydrolytic activity. This balances the mechanical strength and bioavailability of carbon source products, ensuring structural integrity and stable carbon release for more than 30 days in wastewater denitrification systems.

[0021] Optionally, the high-density polyethylene has an average molecular weight of 90,000-110,000.

[0022] By adopting the above technical solution, the specific average molecular weight range enables HDPE to have both melt flowability and high compressive strength at the processing temperature. During the melt blending process, a high-density molecular chain entanglement network is formed. By winding modified corn cob powder and polybutylene terephthalate and other components, the overall structural density is enhanced, effectively improving the shear strength of the composite carbon source. At the same time, its hydrophobicity slows down the water molecule penetration rate and avoids the short-term disintegration of the carbon source. By constructing a "rigid-flexible" composite framework with flexible segments of polybutylene adipate terephthalate, the problems of fragility of traditional bio-carbon sources and high energy consumption in the processing of synthetic polymer carbon sources are solved. When the average molecular weight is below 90,000, insufficient chain entanglement leads to a decrease in mechanical strength, while when it is above 110,000, the extrusion resistance increases due to the excessively high melt viscosity. This ensures the long-term structural integrity of the carbon source under hydraulic impact, providing a stable carrier for microbial attachment.

[0023] Optionally, the average molecular weight of the polyvinyl alcohol is 100,000-110,000.

[0024] By employing the above technical solution, polyvinyl alcohol with an average molecular weight of 100,000-110,000 balances the rapid start-up performance and long-term structural integrity of the carbon source. Carbon release kinetics are optimized through the synergistic effect of hydrophilic segments of polyvinyl alcohol and hydrophobic segments of high-density polyethylene. It ensures that the density of hydroxyl groups is within a controllable hydrolysis range, and maintains structural stability through the semi-crystalline phase region, thus resolving the technical contradiction between insufficient strength of traditional starch carbon sources and delayed start-up of synthetic polymer carbon sources. When the average molecular weight is below 100,000, insufficient chain entanglement leads to excessive hydrophilicity, causing short-term disintegration of the carbon source. When it is above 110,000, the increased rigidity of the molecular chain inhibits hydrolysis activity.

[0025] The second objective of this invention is achieved through the following technical solution: A method for preparing a bio-composite carbon source includes the following steps: Modified corn cob powder, polybutylene adipate terephthalate, high-density polyethylene, polyvinyl alcohol, ethylene bis-stearamide, and starch are mixed evenly and then extruded in a twin-screw extruder to obtain a bio-composite carbon source.

[0026] By adopting the above technical solution, the process reduces energy consumption through one-time extrusion molding, and the product has no risk of secondary pollution. The resulting biocomposite carbon source has both high mechanical stability and controlled carbon release performance, and is efficient, long-lasting, safe and stable, achieving a joint improvement in denitrification performance, environmental friendliness and operating economy.

[0027] The third inventive objective of this invention is achieved through the following technical solution: Application of biological composite carbon sources in the denitrification treatment of biological wastewater or municipal wastewater.

[0028] By adopting the above technical solution, this biological composite carbon source achieves efficient nitrogen removal in denitrification through a cascade carbon release mechanism: Polyvinyl alcohol and starch, as short-term readily degradable components, rapidly dissolve and release small-molecule organic matter, quickly activating heterotrophic denitrifying bacteria to initiate the reduction reactions of nitrates and nitrites; polybutylene adipate terephthalate, as a slow-release carbon source, has its molecular chains slowly hydrolyzed in the wastewater environment, ensuring a long-term supply of electron donors; modified corn cob powder provides a high specific surface area and microporous structure, creating a stable carrier for microbial attachment and proliferation, while simultaneously adsorbing and settling suspended solids and heavy metal pollutants in the wastewater; Therefore, by synergistically combining modified corn cob powder with polybutylene adipate / polyvinyl alcohol, a "rapid-long-lasting" dual-mode carbon release system is constructed to avoid the risk of harmful byproducts from liquid carbon sources (such as methanol). At the same time, the physicochemical interaction between the components—the hydrophilic segments of polyvinyl alcohol and the hydrophobic segments of polybutylene adipate—optimizes carbon release kinetics, improves the denitrification rate and reduces operating costs compared to a single biomass carbon source (such as unmodified corn cob), solves the problem of low denitrification efficiency caused by insufficient carbon source in wastewater treatment plant effluent, and significantly improves the total nitrogen removal rate by simultaneously meeting the requirements of rapid start-up and continuous operation.

[0029] In summary, this application has at least the following beneficial effects: This application comprehensively addresses the technical shortcomings of traditional carbon sources through the synergistic effect of its components: polyvinyl alcohol and starch serve as rapid carbon sources to ensure quick denitrification initiation; enzymatically modified corn cob powder acts as a medium-efficiency carbon source and a microbial carrier; and polybutylene adipate terephthalate (PEG) provides a stable electron donor as a long-lasting carbon source. These three components constitute a "rapid-medium-long-lasting" tiered carbon release system, increasing denitrification efficiency to over 96%. High-density polyethylene (HDPE) constructs a reinforcing network to ensure the product's mechanical strength and long-term stability, while ethylene bis-stearamide (EDS) improves processing fluidity. Together, these two components ensure the structural integrity and good formability of the carbon source under hydraulic impact. The low-temperature neutral conditions of the modification process and the product's low-dissolution characteristics achieve efficient denitrification while reducing energy consumption, avoiding secondary pollution, and lowering operating costs. Ultimately, this application's bio-composite carbon source achieves a balance between denitrification performance, structural stability, environmental friendliness, and operational economy.

[0030] Instruction manual illustrations Figure 1 The graph shows the carbon release detection results for Example 1 and Comparative Examples 1-3. Figure 2 The graph shows the carbon release detection results for Example 1 and Comparative Examples 4-5. Detailed Implementation

[0031] raw material The corn cob powder was purchased from farmers and consisted of natural corn cobs harvested that year. The cobs were crushed and sieved to obtain different fineness specifications for later use. Laccase and hemicellulase are commercially available products from Nanjing Dulai Biotechnology Co., Ltd., available in various activity levels.

[0032] Preparation Example 1 A modified corn cob powder utilizes the synergistic effect of laccase and hemicellulase to directionally biodegrade the lignocellulose structure of the corn cob powder. After treatment, the specific surface area and porosity of the corn cob powder significantly increase, and a rich microporous structure forms on the surface, thereby greatly enhancing its effectiveness as a microbial attachment carrier and its potential for releasing bioavailable carbon.

[0033] The preparation method of modified core powder includes the following steps: S1. Raw material preparation: Weigh 1000g of corn cob powder (80 mesh) as raw material for later use. Weigh laccase with an enzyme activity of 100,000 U / g and hemicellulase with an enzyme activity of 50,000 U / g, mix them in a mass ratio of 1:1 to prepare a compound enzyme preparation. S2. Compound enzymatic hydrolysis: 200g of corn cob powder and 0.8g of the above compound enzyme preparation are added to 4000g of water and placed in a reactor. Under constant temperature conditions of 16±2℃, the mixture is continuously stirred at 150 rpm for 60 minutes to carry out the enzymatic hydrolysis reaction. S3. Washing and Drying: After the enzymatic hydrolysis reaction is completed, the mixture is filtered and separated, and the solid product is collected. The solid product is washed three times with deionized water to remove residual enzyme solution and water-soluble impurities. The washed solid is then dried in a 60°C forced-air drying oven until constant weight.

[0034] S4. Crushing and sieving: The dried material is crushed and sieved through a 100-mesh sieve to obtain modified corn cob powder.

[0035] Preparation Example 2 The modified corn cob powder differs from that in Preparation Example 1 in that the corn cob powder used as raw material has a particle size of 10 mesh.

[0036] Preparation Example 3 The modified corn cob powder differs from that in Preparation Example 1 in that the corn cob powder used as raw material has a particle size of 20 mesh.

[0037] Preparation Example 4 The modified corn cob powder differs from that in Preparation Example 1 in that the corn cob powder used as raw material has a particle size of 100 mesh.

[0038] Preparation Example 5 The modified corn cob powder differs from that in Preparation Example 1 in that the corn cob powder used as raw material has a particle size of 200 mesh.

[0039] Preparation Example 6 The modified corn cob powder differs from Preparation Example 1 in that its laccase activity is 40,000 U / g.

[0040] Preparation Example 7 The modified corn cob powder differs from that in Preparation Example 1 in that its laccase activity is 80,000 U / g.

[0041] Preparation Example 8 The modified corn cob powder differs from Preparation Example 1 in that its laccase activity is 120,000 U / g.

[0042] Preparation Example 9 The modified corn cob powder differs from that in Preparation Example 1 in that its laccase activity is 200,000 U / g.

[0043] Preparation Example 10 The modified corn cob powder differs from that in Preparation Example 1 in that its hemicellulase activity is 10,000 U / g.

[0044] Preparation Example 11 The modified corn cob powder differs from that in Preparation Example 1 in that its hemicellulase activity is 40,000 U / g.

[0045] Preparation Example 12 The modified corn cob powder differs from that in Preparation Example 1 in that its hemicellulase activity is 60,000 U / g.

[0046] Preparation Example 13 The modified corn cob powder differs from that in Preparation Example 1 in that its hemicellulase activity is 100,000 U / g.

[0047] Preparation Example 14 The modified corn cob powder differs from that in Preparation Example 1 in that the enzymatic hydrolysis process is carried out at an ambient temperature of 10°C.

[0048] Preparation Example 15 The modified corn cob powder differs from that in Preparation Example 1 in that the enzymatic hydrolysis process is carried out at an ambient temperature of 25°C.

[0049] Preparation Example 16 The modified corn cob powder differs from that in Preparation Example 1 in that the enzymatic hydrolysis process is carried out at an ambient temperature of 30°C.

[0050] Preparation Example 17 The modified corn cob powder differs from that in Preparation Example 1 in that the enzymatic hydrolysis process is carried out at an ambient temperature of 40°C.

[0051] Preparation Example 18 The modified corn cob powder differs from that in Preparation Example 1 in that the pH of the enzymatic hydrolysis process is 4.0.

[0052] Preparation Example 19 The modified corn cob powder differs from that in Preparation Example 1 in that the pH of the enzymatic hydrolysis process is 6.5.

[0053] Preparation Example 20 The modified corn cob powder differs from that in Preparation Example 1 in that the pH of the enzymatic hydrolysis process is 7.5.

[0054] Preparation Example 21 The modified corn cob powder differs from that in Preparation Example 1 in that the pH of the enzymatic hydrolysis process is 9.0.

[0055] Preparation Example 22 The modified corn cob powder differs from that in Preparation Example 1 in that the enzymatic hydrolysis time is 30 min.

[0056] Preparation Example 23 The modified corn cob powder differs from that in Preparation Example 1 in that the enzymatic hydrolysis time is 50 min.

[0057] Preparation Example 24 The modified corn cob powder differs from that in Preparation Example 1 in that the enzymatic hydrolysis time is 120 min.

[0058] Preparation Example 25 The modified corn cob powder differs from that in Preparation Example 1 in that the enzymatic hydrolysis time is 150 min.

[0059] Comparative Preparation Example 1 The modified corn cob powder differs from Preparation Example 1 in that it uses an equal mass of single laccase instead of the complex enzyme.

[0060] Comparative Preparation Example 2 The modified corn cob powder differs from Preparation Example 1 in that it uses an equal mass of single hemicellulase instead of the complex enzyme.

[0061] Example 1 A bio-composite carbon source, comprising modified corn cob powder, polybutylene adipate terephthalate, high-density polyethylene, polyvinyl alcohol, ethylene bis-stearamide, and starch, is prepared by melt blending and extrusion molding. It possesses excellent mechanical strength, processing performance, and denitrification efficiency, and is suitable for denitrification treatment of biological wastewater or municipal wastewater.

[0062] The modified corn cob powder was prepared by Preparation Example 1.

[0063] The average molecular weight of polybutylene adipate terephthalate is 70,000, the average molecular weight of high-density polyethylene is 100,000, and the average molecular weight of polyvinyl alcohol is 108,000.

[0064] A method for preparing a bio-composite carbon source includes the following steps: S1. Raw material preparation: Weigh 100 g of modified corn cob powder, 9 g of polybutylene adipate terephthalate, 6 g of high-density polyethylene, 12.5 g of polyvinyl alcohol, 5 g of ethylene bis-stearamide, 15 g of starch, and 0.3 g of antioxidant 1010 and put them into a high-speed mixer. Mix at room temperature for 10-15 minutes until all components are evenly dispersed to obtain a premix.

[0065] S3. Melt Extrusion: The above premixed material is fed into a twin-screw extruder for melt blending and extrusion granulation. The extrusion process parameters are set as follows: screw speed 80 rpm, feed speed 6 rpm, and the temperature settings of each section of the extruder from the feed port to the die head are set to 125℃, 135℃, 140℃, 135℃, 135℃, and 135℃. After the material undergoes conveying, melting, shearing, and mixing in the extruder, it is extruded from the die head (orifice diameter of 3mm). S4. Cooling and Cutting: The extruded strip material immediately enters a water tank for cooling and solidification. After cooling, the strip material is cut by a pelletizer to obtain columnar particles with a length of 4±1mm.

[0066] S5. Drying: Dry the cut particles at 55℃ until the moisture content is less than 2wt% to obtain the finished bio-composite carbon source.

[0067] Comparative Example 1 A bio-composite carbon source, which differs from Example 1 in that it uses the modified corn cob powder prepared in Comparative Preparation Example 1 in the same mass instead of the modified corn cob powder.

[0068] Comparative Example 2 A bio-composite carbon source, which differs from Example 1 in that it uses modified corn cob powder prepared in Comparative Preparation Example 2 of equal mass instead of modified corn cob powder.

[0069] Comparative Example 3 A bio-composite carbon source, which differs from Example 1 in that it uses corn cob powder of equal mass and 100 mesh instead of modified corn cob powder.

[0070] Comparative Example 4 A bio-composite carbon source, which differs from Example 1 in that it uses an equal mass of modified corn cob powder instead of polybutylene adipate terephthalate.

[0071] Comparative Example 5 A bio-composite carbon source, which differs from Example 1 in that it uses equal mass of modified corn cob powder instead of polyvinyl alcohol and starch.

[0072] Example 2 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 2.

[0073] Example 3 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 3.

[0074] Example 4 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 4.

[0075] Example 5 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 5.

[0076] Example 6 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 6.

[0077] Example 7 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 7.

[0078] Example 8 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 8.

[0079] Example 9 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 9.

[0080] Example 10 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 10.

[0081] Example 11 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 11.

[0082] Example 12 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 12.

[0083] Example 13 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 13.

[0084] Example 14 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 14.

[0085] Example 15 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 15.

[0086] Example 16 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 16.

[0087] Example 17 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 17.

[0088] Example 18 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 18.

[0089] Example 19 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 19.

[0090] Example 20 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 20.

[0091] Example 21 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 21.

[0092] Example 22 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 22.

[0093] Example 23 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 23.

[0094] Example 24 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 24.

[0095] Example 25 A bio-composite carbon source, which differs from Example 1 in that the modified corn cob powder was prepared in Preparation Example 25.

[0096] Example 26 A bio-composite carbon source, which differs from Example 1 in that the average molecular weight of polybutylene adipate terephthalate is 50,000.

[0097] Example 27 A biocomposite carbon source, which differs from Example 1 in that the average molecular weight of polybutylene adipate terephthalate is 60,000.

[0098] Example 28 A bio-composite carbon source, which differs from Example 1 in that the average molecular weight of polybutylene adipate terephthalate is 80,000.

[0099] Example 29 A bio-composite carbon source, which differs from Example 1 in that the average molecular weight of polybutylene adipate terephthalate is 100,000.

[0100] Example 30 A bio-composite carbon source, which differs from Example 1 in that the high-density polyethylene has an average molecular weight of 50,000.

[0101] Example 31 A biocomposite carbon source, which differs from Example 1 in that the high-density polyethylene has an average molecular weight of 90,000.

[0102] Example 32 A bio-composite carbon source, which differs from Example 1 in that the high-density polyethylene has an average molecular weight of 110,000.

[0103] Example 33 A bio-composite carbon source, which differs from Example 1 in that the high-density polyethylene has an average molecular weight of 160,000.

[0104] Example 34 A bio-composite carbon source, which differs from Example 1 in that the average molecular weight of polyvinyl alcohol is 50,000.

[0105] Example 35 A bio-composite carbon source, which differs from Example 1 in that the average molecular weight of polyvinyl alcohol is 100,000.

[0106] Example 36 A biocomposite carbon source, which differs from Example 1 in that the average molecular weight of polyvinyl alcohol is 110,000.

[0107] Example 37 A biocomposite carbon source, which differs from Example 1 in that the average molecular weight of polyvinyl alcohol is 180,000.

[0108] The bio-composite carbon sources of Examples 1-37 and Comparative Examples 1-5 were tested, and the test results are as follows.

[0109] Carbon release detection Five portions of each biological composite carbon source were added to 500 portions of water. The water was changed every 24 hours and the COD of the leachate was measured for a total of 720 hours. The results were expressed as 24h, 48h, 96h, 120h, 144h, 168h, 336h, and 720h.

[0110] Compressive strength test Ten columnar particles with regular shape and no surface defects were selected from the prepared biocomposite carbon source particles as samples, and the original dimensions (diameter and height) of each sample were measured and recorded. Place the specimen upright in the center of the lower platen of the universal testing machine, start the testing machine, and apply a static loading compression rate of 1 mm / min to the specimen until the specimen breaks or the deformation reaches the preset value (height reduced by 25%). Obtain the maximum load before the specimen breaks or at the specified deformation, calculate the compressive strength based on the original cross-sectional area of ​​the specimen, and take the average value of the results of 10 parallel specimens as the test result.

[0111] 30-day immersion splitting rate test From the prepared biocomposite carbon source particles, select columnar particles with regular shape and no surface defects, take 10-15g as a sample, set up 20 samples, measure and record the specific mass of each sample, and denot it as M0. Each sample was placed in an Erlenmeyer flask, and deionized water was added to a beaker at a ratio of 50 mL deionized water per 1 g sample mass. The samples were then allowed to stand and soak at room temperature for 30 days. After soaking for 30 days, pour the soaking solution and the sample into a set of standard test sieves with a mesh size of 1 mm. Rinse the sample on the sieve gently with a slow stream of water until the water runs clear, washing away all the small fragments caused by the breakage. The remaining, unbroken carbon source particles were transferred to a petri dish and dried at 60°C to constant weight. After cooling, weigh the undisturbed particles after drying, and record the mass as M1. Calculate the splitting rate: [(M0-M1) / M0]×100% Table 1. Results of Carbon (COD) Emission Rate Detection Example 1 mg / L 449.2 185.6 149.2 139.4 142.2 104.4 86.8 60.2 30.8 Comparative Example 1 mg / L 370.5 105.2 88.6 70.1 65.3 60.4 50.2 15.4 5.1 Comparative Example 2 mg / L 380.8 125.8 95.4 75.6 71.8 62.1 55.6 18.2 6.5 Comparative Example 3 mg / L 355.3 62.1 48.9 40.2 38.7 32.5 28.5 10.2 3.2 Comparative Example 4 mg / L 420.5 160.2 125.6 98.8 90.8 65.1 50.3 15.5 8.5 Comparative Example 5 mg / L 155.8 120.5 105.8 98.2 95.6 90.4 70.6 28.5 13.5 Example 2 mg / L 420.4 158.4 130.5 121.8 109.2 82.7 68.8 48.6 23.5 Example 3 mg / L 440.5 180 140.5 135.8 135.8 94 76.5 55.2 30.5 Example 4 mg / L 447.5 178.5 142.5 128.8 132.54 93.8 76.3 55 30.4 Example 5 mg / L 430.0 180.4 142.2 138.2 101.6 90.9 73.0 52.8 25.7 Example 6 mg / L 400.5 135.6 100.2 82.5 90.6 75.8 60.2 22.8 18.2 Example 7 mg / L 445.7 182.5 144.5 135.2 130.0 95.6 80.6 52.9 26.8 Example 8 mg / L 446.0 183.9 145.8 136.1 131.8 96.6 81.3 53.2 27.4 Example 9 mg / L 440.8 124.2 118 95.5 110 93.5 76.2 30.2 15.6 Example 10 mg / L 420.8 128.9 102.5 83.8 86.9 80.5 62.1 39.5 18.8 Example 11 mg / L 443.7 180.7 140.5 130.6 125.7 92.8 78.0 50.8 25.5 Example 12 mg / L 444.9 181.7 141.5 131.6 126.3 93.9 79.8 51.9 26.2 Example 13 mg / L 444.5 135 118.8 94.2 95.3 95 76.5 35.4 16.7 Example 14 mg / L 420.6 115.2 90.1 72.8 89.6 68.9 54.2 28.8 17.2 Example 15 mg / L 430.5 132.1 115.2 96.6 95.8 90.1 72.5 35.2 21.5 Example 16 mg / L 420.2 125.6 105.8 97.1 95.9 86.2 66.5 32.8 20.4 Example 17 mg / L 420.8 107.6 85.2 72.5 80.2 60.8 48.1 26.9 16.2 Example 18 mg / L 428.9 140.5 115.8 85.1 90.5 77.3 57.6 32.9 17.8 Example 19 mg / L 440.1 163.9 137.5 112.0 115.5 97.8 75.2 39.9 22.4 Example 20 mg / L 410.5 158.9 132.1 106.5 110.3 92.9 70.8 37.5 21.2 Example 21 mg / L 320.6 148.2 121.8 89.6 97.8 82.6 61.5 34.2 18.5 Example 22 mg / L 448.5 140.3 121.0 102.4 105.1 77.2 70.5 45.8 25.2 Example 23 mg / L 451.5 165.3 119.0 113.5 121.1 94.2 76.7 45.5 25.7 Example 24 mg / L 454.2 185 148.8 130.3 139.9 104.1 86.6 55.3 32.6 Example 25 mg / L 442.8 184.5 148.3 142.9 132.5 105.8 84.3 55 32.4 Example 26 mg / L 455.1 158.9 140.5 135.2 140.8 109.1 95.2 55.2 21.5 Example 27 mg / L 445.8 154.5 138 132.8 149.9 105.2 94.8 23.8 31.5 Example 28 mg / L 440.2 153.8 147.2 131.9 148.8 102.5 92.1 42.1 22.2 Example 29 mg / L 430.5 150.1 144.5 139.2 145.1 100.8 90.1 38.5 28.1 Example 30 mg / L 435.2 132.1 116.5 131.2 125 91.8 73.9 44.1 21 Example 31 mg / L 448.5 135.4 119.1 123.5 127 94.3 76.7 45.5 20.7 Example 32 mg / L 448.8 135.5 119.2 143.6 128.2 94.4 76.8 45.6 22.8 Example 33 mg / L 440.8 133.9 117.8 122.4 126.6 93.2 75.6 44.8 20.3 Example 34 mg / L 480.6 195.8 160.2 122.1 108.5 94.9 72.2 43.5 27.8 Example 35 mg / L 449 185.5 150.1 125.5 111.1 84.3 76.7 49.5 27.7 Example 36 mg / L 448.5 165.6 139.2 122.6 130.2 105.4 92.8 54.6 30.2 Example 37 mg / L 420.5 160.8 142.5 120.2 133.5 109.8 79.2 52.1 29.1 Table 2. Results of compressive strength and 30-day immersion cracking rate tests Example 1 12.0 4.0 Example 2 10 8.9 Example 3 11.8 4.2 Example 4 11.5 4.5 Example 5 9.5 9.1 Example 6 9.0 12 Example 7 11.5 4.5 Example 8 11.3 4.8 Example 9 11 5.7 Example 10 9.5 11.6 Example 11 11.8 4.3 Example 12 11.6 4.5 Example 13 11.2 4.8 Example 14 8.5 14.3 Example 15 10.5 7.3 Example 16 9.3 12.1 Example 17 7.1 18.3 Example 18 7.5 16.2 Example 19 8.5 13.0 Example 20 11.9 4.1 Example 21 10.4 8.1 Example 22 9.1 11.2 Example 23 11.8 4.3 Example 24 11.5 4.5 Example 25 11.0 5.5 Example 26 8.9 22 Example 27 11. 5.5 Example 28 10.5 6.5 Example 29 9.3 15.3 Example 30 7.3 30 Example 31 11.8 4.2 Example 32 12 4.0 Example 33 10 81 Example 34 10 23.3 Example 35 12 4.2 Example 36 12.1 3.9 Example 37 11.5 4.5 Comparative Example 1 5.5 28.7 Comparative Example 2 8.0 15.0 Comparative Example 3 8.5 12.3 Comparative Example 4 9.7 18.3 Comparative Example 5 12.5 3.8 Comparing Example 1 and Comparative Examples 1-3, it can be seen that: Combined with appendix Figure 1 It can be seen that the COD release rate of Examples 1 and Comparative Examples 1-3 generally decreased over time. The difference between Examples 1 and Comparative Examples 1-3 lies in their different bio-based components. Example 1 is the modified corn cob powder prepared in Preparation Example 1, Comparative Example 1 is the modified corn cob powder prepared in Comparative Preparation Example 1, Comparative Example 2 is the modified corn cob powder prepared in Comparative Preparation Example 2, and Comparative Example 3 is unmodified corn cob powder.

[0112] In Example 1, the COD test results of the first 24-hour leachate were all higher than those of Comparative Examples 1-3. Meanwhile, in the subsequent testing process, the COD test results of the leachate of Comparative Examples 1-3 decreased rapidly over time, and the COD test results of the leachate of Example 1 also decreased over time. When there was a slow decreasing zone, the COD test results of the leachate of Example 1 were still higher than those of Comparative Examples 1-3 after passing through the slow decreasing zone, and the COD test results of Example 1 remained significantly higher than those of Comparative Examples 1-3 before slowly decreasing.

[0113] Combined with the appendix Figure 2 Compared with Example 1, Comparative Examples 4-5 show that Comparative Example 4 has a lower COD level maintained in the slow descent zone and ends faster than Example 1, and its COD level in the later stage is significantly lower than that of Example 1; Comparative Example 5 has a significantly lower initial COD than Example 1, and the slow descent zone ends faster than Example 1.

[0114] Therefore, compared with Comparative Examples 1-5, Example 1 has the ability to quickly activate the denitrification system with high initial COD, and then release carbon in a controllable and long-term manner with a stable and maintained step-by-step carbon release curve, providing an excellent COD supply environment for the denitrification system.

[0115] The reason for this is that the bio-composite carbon source of this application achieves rapid start-up and graded release through the synergistic effect of three components: "rapid carbon source (polyvinyl alcohol / starch), medium-efficiency carbon source (modified corn cob powder), and long-lasting carbon source (polybutylene adipate terephthalate)".

[0116] Modified corn cob powder is enzymatically modified using a combination of laccase and hemicellulase. Based on the composition of corn cob powder, the combination enzymes synergistically construct a "lignin preferential degradation" mechanism during enzymatic modification. After laccase destroys the cross-linked structure of lignin phenolic units, hemicellulase rapidly decomposes the exposed hemicellulose network. Under the dual action, the specific surface area and porosity of corn cob powder are significantly increased, thereby maximizing the bioavailability of corn cob and the directional release of bioavailable carbon components in corn cob. A high-porosity carrier structure is constructed to enhance microbial attachment and provide a stable carbon release channel for subsequent composite carbon sources. This overcomes the defects of its original dense structure and slow carbon release, and provides a core slow-release carbon pool and biofilm growth interface for composite carbon sources. In the early stages, polyvinyl alcohol and starch, as short-term and easily degradable components, rapidly dissolve and release small molecule organic matter in the initial stage of addition, quickly activating the denitrifying bacteria and enabling the biological denitrification system to start up quickly. As the COD provided by the decomposition of polyvinyl alcohol and starch gradually decreases in the early stage, the surface of the modified corn cob powder and the liquid phase contact increase accordingly. Its carbon release efficiency begins to play a role and continues to increase as it approaches the middle stage, in order to compensate for the decrease in COD provided by the decomposition of polyvinyl alcohol and starch. Under the combination of this application, a slow decline zone of COD release is formed in the middle stage, which maintains a stable COD supply in the middle stage. Then, in this application, polybutylene adipate terephthalate is used as a long-lasting slow-release carbon source. In the water environment, carbon is released continuously and slowly through the slow non-biological hydrolysis and microbial degradation of its ester bonds, ensuring that the denitrification system has a stable and continuous electron donor in the long-term operation, and making up for the lack of COD release in the later stage of modified corn cob powder. Modified corn cob powder and polybutylene adipate terephthalate constitute a dual long-term carbon supply system of "bio-matrix slow release" and "synthetic polymer slow release"—the two have different degradation mechanisms (enzymatic / hydrolysis and microbial degradation), complementary release kinetics, and combined with the rapid release of polyvinyl alcohol / starch, thus forming a stepped carbon release curve that covers the entire denitrification process with rapid start-up, efficient nitrogen removal, and stable maintenance. This synergistic mechanism enables controllable carbon release rate and cycle, improves the system's nitrogen removal efficiency to over 96%, and avoids the phenomenon of "burst release" or "starvation" of a single carbon source. Traditional single carbon sources (such as methanol) or unmodified biomass carbon sources cannot achieve this controllable and long-term carbon release mode.

[0117] Furthermore, combining the compressive strength test and the 30-day immersion splitting rate test of Example 1 and Comparative Examples 1-5, the compressive strength of Example 1 is better than that of Comparative Examples 1-5, and the 30-day immersion splitting rate of Example 1 is lower than that of Comparative Examples 1-5. Therefore, the modified corn cob powder, polyvinyl alcohol, starch, and polybutylene terephthalate hydrolyzed by the compound enzyme in this application are helpful in the molding of the biocomposite carbon source and the stability of the molded structure, so that the biocomposite carbon source of this application has high mechanical strength and good stability in water.

[0118] The final product has the combined advantages of high denitrification efficiency, long working cycle and high structural stability. It solves the technical problems of high safety risk and difficult addition control of traditional liquid carbon sources, as well as low denitrification efficiency, uncontrollable carbon release and easy breakage and loss of solid biomass carbon sources. Thus, a composite solid carbon source is constructed that is efficient, long-lasting, safe and stable.

[0119] Comparing Example 1 and Examples 2-5, we can see that: The stability of COD release rate is denoted by the buffering effect of the stepwise decrease in COD release rate. The COD release rate stability of Example 1 is better than that of Examples 3-4, and the COD release rate stability of Examples 3-4 is better than that of Examples 2 and 5. The compressive strength of Example 1 is better than that of Examples 3-4, and the compressive strength of Examples 3-4 is better than that of Examples 2 and 5. The 30-day splitting rate of Example 1 is lower than that of Examples 3-4, and the 30-day splitting rate of Examples 3-4 is lower than that of Examples 2-5. Therefore, a particle size of 20-100 mesh is preferred for the modified corn cob powder raw material in this application.

[0120] Comparing Example 1 and Examples 6-9, we can see that: The COD release rate stability of Examples 1, 7, and 8 is better than that of Example 6; the compressive strength and 30-day soaking decomposition rate of Examples 1, 7, and 8 are better than those of Example 6; the COD release rate stability of Examples 1, 7, and 8 is better than that of Example 9; the denitrification performance of Example 1 is better than that of Example 9; and the compressive strength and 30-day soaking decomposition rate of Examples 1, 7, and 8 are better than those of Example 9. Therefore, a laccase activity of 8-12 U / g is preferred in this application.

[0121] Comparing Example 1 and Examples 10-13, we can see that: The COD release rate stability of Examples 1, 11, and 12 is superior to that of Example 10; the compressive strength and 30-day immersion cell division rate of Examples 1, 11, and 12 are superior to those of Example 10; the COD release rate stability of Examples 1, 11, and 12 is superior to that of Example 46; and the compressive strength and 30-day immersion cell division rate of Examples 1, 11, and 12 are superior to those of Example 13. Therefore, a hemicellulase activity of 40,000-60,000 U / g is preferred in this application.

[0122] Comparing Example 1 and Examples 14-17, we can see that: The COD release rate stability of Example 1 is better than that of Examples 15-16, and the COD release rate stability of Examples 15-16 is better than that of Examples 14 and 17. The compressive strength of Example 1 is better than that of Examples 15-16, and the compressive strength of Examples 15-16 is better than that of Examples 14 and 17. The 30-day cell division rate of Example 1 is lower than that of Examples 15-16, and the 30-day cell division rate of Examples 15-16 is lower than that of Examples 14 and 17. Therefore, the enzymatic hydrolysis temperature of the modified corn cob powder in this application is preferably 10-25℃.

[0123] Comparing Example 1 and Examples 18-21, we can see that: The COD release rate stability of Example 1 is better than that of Examples 19-20, and the COD release rate stability of Examples 19-20 is better than that of Examples 18 and 21. The compressive strength of Example 1 is better than that of Examples 19-20, and the compressive strength of Examples 19-20 is better than that of Examples 18 and 21. The 30-day cell division rate of Example 1 is lower than that of Examples 19-20, and the 30-day cell division rate of Examples 19-20 is lower than that of Examples 18 and 21. Therefore, the enzymatic hydrolysis pH of the modified corn cob powder of this application is preferably 6.5-7.5.

[0124] Comparing Example 1 and Examples 22-25, we can see that: The COD release rates of Examples 1 and 24-25 are similar in stability and superior to those of Examples 22-23; the compressive strength of Example 1 is superior to that of Examples 22-25; the 30-day splitting rate of Example 1 is lower than that of Examples 22-25. Therefore, the enzymatic hydrolysis time of 50-90 min for the modified corn cob powder of this application is preferred.

[0125] Comparing Example 1 and Examples 26-29, we can see that: The COD release rate stability of Example 1 is better than that of Examples 27-28, and the COD release rate stability of Examples 27-28 is better than that of Examples 26 and 29. The compressive strength of Example 1 is better than that of Examples 27-28, and the compressive strength of Examples 27-28 is better than that of Examples 26 and 29. The 30-day cell division rate of Example 1 is lower than that of Examples 27-28, and the 30-day cell division rate of Examples 27-28 is lower than that of Examples 26 and 29. Therefore, the average molecular weight of butylene terephthalate adipic acid of this application is preferably 60,000-80,000.

[0126] Comparing Example 1 and Examples 30-33, we can see that: The COD release rate stability of Example 1 is better than that of Examples 31-32, and the COD release rate stability of Examples 31-32 is better than that of Examples 30 and 33. The compressive strength of Example 1 is better than that of Examples 31-32, and the compressive strength of Examples 31-32 is better than that of Examples 30 and 33. The 30-day decomposition rate of Example 1 is lower than that of Examples 31-32, and the 30-day decomposition rate of Examples 31-32 is lower than that of Examples 30 and 33. Therefore, an average molecular weight of 90,000-110,000 for the high-density polyethylene of this application is preferred.

[0127] Comparing Example 1 and Examples 34-37, we can see that: The COD release rate stability of Example 1 is better than that of Examples 35-36, and the COD release rate stability of Examples 35-36 is better than that of Examples 34 and 37. The compressive strength of Example 1 is better than that of Examples 35-36, and the compressive strength of Examples 35-36 is better than that of Examples 34 and 37. The 30-day decomposition rate of Example 1 is lower than that of Examples 35-36, and the 30-day decomposition rate of Examples 35-36 is lower than that of Examples 34 and 37. Therefore, an average molecular weight of 100,000-110,000 for the polyvinyl alcohol in this application is preferred.

[0128] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of protection claimed by the present invention, they are protected by patent law.

Claims

1. A bio-composite carbon source, characterized in that, It is obtained by mixing and extruding modified corn cob powder, polybutylene adipate terephthalate, high-density polyethylene, polyvinyl alcohol, ethylene bis-stearamide, and starch; The modified corn cob powder is obtained by enzymatic hydrolysis of corn cob powder using a complex enzyme consisting of laccase and hemicellulase.

2. The bio-composite carbon source according to claim 1, characterized in that, The method for preparing the modified corn cob powder includes the following steps: Add corn cob powder and compound enzyme to water and stir continuously to carry out enzymatic hydrolysis; After enzymatic hydrolysis, the corn cob powder is washed and dried to obtain modified corn cob powder. The enzymatic hydrolysis time is 50-90 min; The enzymatic hydrolysis temperature is 10-25℃; The pH of the enzymatic hydrolysis environment is 6.5-7.

5.

3. The bio-composite carbon source according to claim 2, characterized in that, The enzyme activity of the laccase is 80,000-120,000 U / g.

4. A bio-composite carbon source according to claim 2, characterized in that, The enzyme activity of the hemicellulase is 40,000-60,000 U / g.

5. A bio-composite carbon source according to claim 1, characterized in that, The corn cob powder has a particle size of 20-100 mesh.

6. A bio-composite carbon source according to claim 1, characterized in that, The average molecular weight of the polybutylene adipate terephthalate is 60,000-80,000.

7. A bio-composite carbon source according to claim 1, characterized in that, The high-density polyethylene has an average molecular weight of 90,000-110,000.

8. A bio-composite carbon source according to claim 1, characterized in that, The average molecular weight of the polyvinyl alcohol is 100,000-110,000.

9. A method for preparing a bio-composite carbon source according to any one of claims 1-8, characterized in that, Includes the following steps: Modified corn cob powder, polybutylene adipate terephthalate, high-density polyethylene, polyvinyl alcohol, ethylene bis-stearamide, and starch are mixed evenly and then extruded in a twin-screw extruder to obtain a bio-composite carbon source.

10. The application of the biological composite carbon source according to any one of claims 1-8 in the denitrification treatment of biological wastewater or municipal wastewater.

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