Preparation method and application of high-mechanical-strength straw resourceized slow-release carbon source material

Abstract

The application relates to a preparation method and application of a high-mechanical-strength straw resourceized slow-release carbon source material, and relates to a preparation method and application of a carbon source material. The application aims to solve the problems of insufficient nitrogen pollutant removal efficiency in wastewater treatment and insufficient toughness of conventional carbon source materials. The method comprises the following steps: 1, preparing straw powder; 2, preparing a crosslinking agent solution; and 3, preparing a slow-release carbon source material. The high-mechanical-strength straw resourceized slow-release carbon source material is applied in microbial remediation of contaminated water bodies. In 20-day 5-cycle experiments, the removal rates of different concentrations of nitrate nitrogen all reach more than 80%, and the removal effect is basically close to that of a small-molecule liquid external carbon source such as sodium acetate commonly used in current sewage treatment plants. The application can obtain a high-mechanical-strength straw resourceized slow-release carbon source material.

Description

Technical Field

[0001] This invention relates to a method for preparing carbon source materials and their applications. Background Technology

[0002] With industrial development and population growth, nitrogen pollution has become one of the most pressing and widespread water pollution problems globally. Nitrogen mainly exists in wastewater in the form of ammonia nitrogen, nitrate, and nitrite. Excessive nitrogen discharge leads to eutrophication, causing excessive algal growth, depleting dissolved oxygen, damaging aquatic ecosystems, and even causing serious water quality problems. Therefore, developing efficient nitrogen removal technologies is of paramount importance for water health and ecological balance. Nitrogen removal technologies typically include physical, chemical, and biological methods. Physical methods, mainly based on adsorption or separation techniques, can directly remove nitrogen from wastewater, but are costly and easily generate nitrogen-rich solid waste. Chemical methods remove nitrogen by adding chemical agents, offering faster treatment speeds and the ability to treat high-concentration nitrogen wastewater, but may introduce new chemical pollutants and are economically costly. Biological methods utilize microorganisms for nitrification and denitrification, converting nitrogen into nitrogen gas for removal. They offer advantages such as low operating costs, environmental friendliness, and sustainable operation, but the process may be limited by environmental factors and requires high-level process control.

[0003] In nitrate removal, the low carbon source content in wastewater limits denitrification. To improve the efficiency of biological nitrogen removal systems, additional carbon sources are typically added to optimize the C / N ratio when treating nitrogen-containing wastewater, thereby enhancing the activity of denitrifying microorganisms. Sludge and agricultural waste straw are favored due to their availability and low cost. Sludge, as a byproduct of activated sludge systems, has a high organic matter content and contains abundant denitrifying microorganisms; straw, being agricultural waste, not only provides nutrients for microorganisms but also promotes the resource utilization of waste.

[0004] The development of slow-release carbon source materials mainly employs two strategies: pyrolysis and chemical modification. Pyrolysis involves the controlled thermal decomposition of biomass under anoxic or inert atmospheres to obtain biochar, transforming the organic components in the raw material into carbon-rich solid products. However, precise temperature control and regulation of the thermal decomposition rate are complex in this process, and the yield and quality of biochar are strongly influenced by the properties of the raw materials and the pyrolysis conditions. Chemical cross-linking technology uses chemical reactions to link molecular chains, forming a polymer cross-linked network structure to prepare slow-release carbon source materials. Compared to pyrolysis, chemical cross-linking technology can effectively control the microstructure of materials, improving their mechanical properties and stability. Materials prepared using this technology exhibit high durability, maintaining their properties and functions under harsh environmental conditions, thus significantly improving the applicability and reliability of slow-release carbon source materials in environmental remediation. Furthermore, this method allows for the customization of chemical functions to meet specific application needs, such as introducing functional groups that promote microbial growth or increase pollutant degradation through specific cross-linking agents, further enhancing the remediation efficiency and durability of the materials. Therefore, chemical cross-linking shows great potential in preparing highly efficient slow-release carbon source materials for environmental remediation. Summary of the Invention

[0005] The purpose of this invention is to address the problems of insufficient nitrogen pollutant removal efficiency and insufficient toughness of conventional carbon source materials in wastewater treatment, and to provide a method for preparing and applying a high-mechanical-strength slow-release carbon source material from straw resources.

[0006] A method for preparing a high-mechanical-strength, slow-release carbon source material from straw resources is specifically carried out according to the following steps:

[0007] I. Preparation of straw powder:

[0008] The straw is washed, then soaked in NaOH solution for a period of time, taken out and dried, and crushed into powder to obtain pretreated straw powder;

[0009] II. Preparation of crosslinking agent solution:

[0010] Polyvinyl alcohol and sodium alginate were added to distilled water and heated and stirred in a water bath at 90-95°C for a period of time until the polyvinyl alcohol and sodium alginate were completely dissolved. The solution was then cooled at room temperature for a period of time to obtain a crosslinking agent solution.

[0011] III. Preparation of slow-release carbon source materials:

[0012] Add attapulgite to the crosslinking agent solution, then add pretreated straw powder, synergistic components and sugarcane molasses, mix and extrude into spherical particles to obtain small spheres of the mixture, then soak them in a saturated boric acid solution of CaCl2 for 24h to 48h, take them out, dry and sterilize them, and put them into perforated acrylic spheres. The preparation of high mechanical strength straw resource utilization slow-release carbon source material is completed.

[0013] A high-mechanical-strength, slow-release carbon source material from straw is applied in the microbial remediation of polluted water bodies.

[0014] Principles and beneficial effects of this invention:

[0015] This invention utilizes corn stalks, an agricultural waste, to prepare a slow-release carbon source material. This material possesses advantages such as low preparation cost, high denitrification efficiency, and good carbon release effect, making it suitable for nitrogen removal from domestic sewage. It also exhibits high mechanical strength. The invention employs a chemical cross-linking method, adding sugarcane molasses during preparation to increase the material's viscosity, making it less prone to breakage. The added graphene not only increases the production of small-molecule organic matter but also enhances the material's impact resistance to some extent. Simultaneously, the material is encapsulated with acrylic spheres, thereby simultaneously improving the mechanical strength of the carbon source material both physically and chemically, making it less prone to breakage. This solves the problem of carbon source material disintegration caused by prolonged soaking and rapid biofilm formation by microorganisms. It allows for more continuous release of carbon source substances in the denitrification unit of sewage treatment plants, ensuring that the effluent meets standards. This invention achieved a nitrate nitrogen removal rate of over 80% for different concentrations within 20 days and 5 cycles, with a removal effect comparable to that of commonly used small-molecule liquids such as sodium acetate with added carbon sources in sewage treatment plants. Attached Figure Description

[0016] Figure 1 (a) A graph showing the effect of the high mechanical strength straw resource utilization slow-release carbon source material prepared in Example 1 on nitrate removal over different periods of 20 days; Figure 1 (b) A graph showing the effect of the slow-release carbon source material prepared in Comparative Example 1 on nitrate removal over different periods of 20 days;

[0017] Figure 2 (a) The accumulation of nitrite concentration during the removal of nitrate using the high mechanical strength slow-release carbon source material prepared in Example 1 during different 20-day cycles; Figure 2 (b) The accumulation of nitrite concentration during the removal of nitrate using the slow-release carbon source material prepared in Comparative Example 1 over different periods of 20 days;

[0018] Figure 3 (a) The COD concentration of the effluent during the removal of nitrates using the high mechanical strength slow-release carbon source material prepared in Example 1 over different periods of 20 days; Figure 3 (b) The COD concentration in the effluent during the removal of nitrate using the slow-release carbon source material prepared in Comparative Example 1 over different periods of 20 days.

[0019] Figure 4The images show the morphology of the high mechanical strength slow-release carbon source material prepared in Example 1 before and after soaking. (a) is before soaking, and (b) is after soaking for 20 days.

[0020] Figure 5 SEM images of the high mechanical strength straw resource utilization slow-release carbon source material prepared in Example 1 before and after soaking, (a) before soaking, (b) after soaking for 20 days;

[0021] Figure 6 SEM images of the slow-release carbon source material prepared in Example 3 before and after soaking: (a) before soaking, (b) after soaking for 20 days.

[0022] Figure 7 Example 1 describes the high mechanical strength slow-release carbon source material for straw resource utilization and its soaking process.

[0023] Figure 8 The two figures on the left show the BET spectra, pore size distribution, and pore volume analysis of the high mechanical strength straw resource-based slow-release carbon source material prepared in Example 1 before and after nitrate removal; Figure 8 The two figures on the right show the BET spectra, pore size distribution, and pore volume analysis of the slow-release carbon source material prepared in Example 1 before and after nitrate removal.

[0024] Figure 9 The graph shows the surface area analysis of the BET spectrum. In the graph, 1 and 2 are the high mechanical strength straw resource recovery slow-release carbon source materials prepared in Example 1 before and after nitrate removal, and 3 and 4 are the slow-release carbon source materials prepared in Control Example 1 before and after nitrate removal.

[0025] Figure 10 For XRD spectrum analysis, 3 and 4 in the figure are the high mechanical strength straw resource utilization slow-release carbon source materials prepared in Example 1 before and after nitrate removal, and 1 and 2 are the slow-release carbon source materials prepared in Control Example 1 before and after nitrate removal.

[0026] Figure 11 XPS spectra of the high mechanical strength slow-release carbon source material prepared in Example 1 before and after nitrate removal are shown. The two images on the left are before soaking, and the two images on the right are after soaking for 20 days.

[0027] Figure 12 XPS spectra of the slow-release carbon source material prepared in Control Example 1 before and after nitrate removal are shown. The two images on the left are before soaking, and the two images on the right are after soaking for 20 days.

[0028] Figure 13 The figures are FTIR images. In the figures, 1 and 2 are the slow-release carbon source materials prepared in Comparative Example 1, and 3 and 4 are the high mechanical strength slow-release carbon source materials prepared in Example 1. Detailed Implementation

[0029] Specific Implementation Method 1: This implementation method provides a method for preparing a high-mechanical-strength, slow-release carbon source material from straw resources, which is specifically completed according to the following steps:

[0030] I. Preparation of straw powder:

[0031] The straw is washed, then soaked in NaOH solution for a period of time, taken out and dried, and crushed into powder to obtain pretreated straw powder;

[0032] II. Preparation of crosslinking agent solution:

[0033] Polyvinyl alcohol and sodium alginate were added to distilled water and heated and stirred in a water bath at 90-95°C for a period of time until the polyvinyl alcohol and sodium alginate were completely dissolved. The solution was then cooled at room temperature for a period of time to obtain a crosslinking agent solution.

[0034] III. Preparation of slow-release carbon source materials:

[0035] Add attapulgite to the crosslinking agent solution, then add pretreated straw powder, synergistic components and sugarcane molasses, mix and extrude into spherical particles to obtain small spheres of the mixture, then soak them in a saturated boric acid solution of CaCl2 for 24h to 48h, take them out, dry and sterilize them, and put them into perforated acrylic spheres. The preparation of high mechanical strength straw resource utilization slow-release carbon source material is completed.

[0036] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the mass fraction of the NaOH solution mentioned in step one is 1% to 4%; the drying temperature mentioned in step one is 80°C, and the drying time is 30 to 36 hours. The other steps are the same as in Specific Implementation Method One.

[0037] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the particle size of the pretreated straw powder in step one is 300-500 mesh; the soaking time in step one is 3-5 hours. Other steps are the same as in Specific Implementation Method One or Two.

[0038] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in the following ways: the heating and stirring time in step two is 4 to 6 hours; the mass-to-volume ratio of polyvinyl alcohol, sodium alginate, and deionized water in step two is (8g to 16):(1g to 2g):(100mL to 200mL); and the cooling time at room temperature in step two is 10 to 12 hours. Other steps are the same as in Specific Implementation Methods One to Three.

[0039] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the mass ratio of attapulgite clay to the volume ratio of the crosslinking agent solution in step three is (1g~4g):(2mL~8mL); the amount of pretreated straw powder added in step three is 2%~10% of the mass of the crosslinking agent solution. Other steps are the same as in Specific Implementation Methods One to Four.

[0040] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: the synergistic component in step three is graphene; the mass ratio of the synergistic component in step three to the pretreated straw powder is 1:4; and the volume ratio of sugarcane molasses to the crosslinking agent solution in step three is (0.5mL to 2mL):40mL. Other steps are the same as in Specific Implementation Methods One to Five.

[0041] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in the following ways: the particle size of the high mechanical strength straw resource-based slow-release carbon source material mentioned in step three is 2mm to 3mm; the saturated boric acid solution of CaCl2 mentioned in step three refers to the solution of CaCl2 obtained by dissolving CaCl2 in a saturated boric acid solution, wherein the mass fraction of CaCl2 is 4%; the drying temperature mentioned in step three is 80℃ to 100℃, and the drying time is 10h to 14h. Other steps are the same as in Specific Implementation Methods One to Six.

[0042] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: the sterilization described in step three is high-pressure steam sterilization; the perforated acrylic ball described in step three consists of two semicircles with a diameter of 2cm and fasteners, with five holes of 0.5mm to 1.0mm in diameter on each side. The other steps are the same as in Specific Implementation Methods One to Seven.

[0043] Specific Implementation Method Nine: This implementation method is the application of a high mechanical strength straw resource-based slow-release carbon source material in the microbial remediation of polluted water bodies.

[0044] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: a high mechanical strength straw resource-based slow-release carbon source material is added to the polluted water body as an electron donor to stimulate microorganisms to metabolize pollutants; the dosage of the high mechanical strength straw resource-based slow-release carbon source material is 83g / L to 100g / L; the pollutant in the polluted water body is nitrate pollutant; and the microorganisms are activated sludge from a secondary sedimentation tank. Other steps are the same as in Specific Implementation Methods One to Nine.

[0045] The beneficial effects of the present invention are verified using the following embodiments:

[0046] Example 1: A method for preparing a high mechanical strength slow-release carbon source material from straw resources, specifically completed according to the following steps:

[0047] I. Preparation of straw powder:

[0048] The straw was washed and then soaked in a 4% NaOH solution for 4 hours. After being taken out, it was dried in an 80℃ oven for 36 hours. After being taken out and cooled, it was crushed into powder of 300-500 mesh to obtain pretreated straw powder.

[0049] II. Preparation of crosslinking agent solution:

[0050] Add 72g of polyvinyl alcohol and 9g of sodium alginate to 900mL of distilled water, heat and stir in a water bath at 95℃ for 4h until the polyvinyl alcohol and sodium alginate are completely dissolved, and then cool at room temperature for 10h to obtain a crosslinking agent solution.

[0051] III. Preparation of slow-release carbon source materials:

[0052] Add 10g of attapulgite to 20mL of crosslinking agent solution, then add 1.2g of pretreated straw powder, 0.3g of graphene and 1mL of sugarcane molasses. Mix and extrude into spherical particles to obtain small spheres of the mixture. Then soak them in 1000mL of saturated boric acid solution with a mass fraction of 4% CaCl2 for 24h. After taking them out, dry them in an oven at 80℃ for 12h and sterilize them with high-pressure steam. Then put them into perforated acrylic spheres to obtain a slow-release carbon source material of straw resource utilization with high mechanical strength.

[0053] The particle size of the high mechanical strength straw resource-based slow-release carbon source material mentioned in step three is 2mm to 3mm;

[0054] The perforated acrylic ball mentioned in step three consists of two semicircles with a diameter of 2cm and a snap fastener, with five holes of 0.5mm to 1.0mm in diameter on each side.

[0055] Example 2: The method for removing nitrate pollutants from domestic sewage using the high mechanical strength straw resource-based slow-release carbon source material prepared in Example 1 is specifically carried out according to the following steps:

[0056] 1. Three portions (11g each) of the high mechanical strength straw resource utilization slow-release carbon source material prepared in Example 1 were respectively added to three 150mL Erlenmeyer flasks. 120mL of laboratory-grade water was added to each of the three 150mL Erlenmeyer flasks, with nitrate nitrogen concentrations of 10mg / L, 30mg / L, and 50mg / L, respectively. Then, 30mL of secondary sedimentation tank activated sludge was added to each of the three 150mL Erlenmeyer flasks. The above apparatus was then purged with high-purity nitrogen gas for 15 minutes. The nitrogen gas concentration was greater than 99.99%, indicating high-purity nitrogen. After purging, the system was kept in an oxygen-deficient environment.

[0057] 2. The conical flask containing the high mechanical strength straw resource utilization slow-release carbon source material prepared in Example 1, laboratory water, and activated sludge from the secondary sedimentation tank was placed in a constant temperature shaking chamber for the experiment. The hydraulic retention time was 4 days. Water samples were taken every 4 days to analyze the concentrations of nitrate nitrogen, nitrite nitrogen, and chemical oxygen demand (COD). At the same time, the water was replaced. After the water was replaced, nitrogen was stripped and the experiment was continued.

[0058] In step two, the shaking incubation speed is 100 rpm and the temperature is 25℃;

[0059] In step two, replace 100mL of water each time.

[0060] In step two, a rubber tube is connected to the top of the experimental apparatus and then introduced into the water. This ensures an oxygen-deficient environment while also allowing the N2 generated during the experiment to be discharged smoothly.

[0061] In step two, the water supply is changed every 4 days. Since the hydraulic retention time for domestic sewage treatment is generally 6-8 hours and the denitrification reaction time is even longer, 4 days ensures complete reaction. Multiple water changes ensure the continuous release of carbon from the high mechanical strength straw resource utilization slow-release carbon source material.

[0062] The laboratory water composition for step one, with a nitrate nitrogen concentration of 10 mg / L, is as follows: KNO3 (72.14 mg / L), MgSO4·7H2O (102.5 mg / L), CaCl2 (13.88 mg / L), KH2PO4 (N:P = 5:1), EDTA·2Na (25 g / L), FeSO4·7H2O (9 g / L), CuSO4·5H2O (0.25 g / L), ZnSO4 (0.44 g / L), H3BO3 (0.015 g / L), Na2MoO4 (0.22 g / L), MnCl2·4H2O (0.99 g / L), CoCl2·6H2O (0.24 g / L), NiCl2·6H2O (0.19 g / L);

[0063] The laboratory water composition for step one, with a nitrate nitrogen concentration of 30 mg / L, is as follows: KNO3 (216.43 mg / L), MgSO4·7H2O (102.5 mg / L), CaCl2 (13.88 mg / L), KH2PO4 (N:P = 5:1), EDTA·2Na (25 g / L), FeSO4·7H2O (9 g / L), CuSO4·5H2O (0.25 g / L), ZnSO4 (0.44 g / L), H3BO3 (0.015 g / L), Na2MoO4 (0.22 g / L), MnCl2·4H2O (0.99 g / L), CoCl2·6H2O (0.24 g / L), NiCl2·6H2O (0.19 g / L);

[0064] The laboratory water composition for step one, with a nitrate nitrogen concentration of 50 mg / L, is as follows: KNO3 (360.71 mg / L), MgSO4·7H2O (102.5 mg / L), CaCl2 (13.88 mg / L), KH2PO4 (N:P = 5:1), EDTA·2Na (25 g / L), FeSO4·7H2O (9 g / L), CuSO4·5H2O (0.25 g / L), ZnSO4 (0.44 g / L), H3BO3 (0.015 g / L), Na2MoO4 (0.22 g / L), MnCl2·4H2O (0.99 g / L), CoCl2·6H2O (0.24 g / L), and NiCl2·6H2O (0.19 g / L).

[0065] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the 0.3g graphene added in step three of Example 1 is replaced with 0.6g of nano-zero valent iron. All other steps and parameters are the same as in Example 1.

[0066] Comparative Example 2: The difference between Comparative Example 1 and Example 2 is that the high mechanical strength straw resource utilization slow-release carbon source material prepared in Example 1 is replaced with the slow-release carbon source material prepared in Comparative Example 1, and the slow-release carbon source material prepared in Comparative Example 1 is used to remove nitrate pollutants from domestic sewage. All other steps and parameters are the same as in Example 2.

[0067] Figure 1 (a) A graph showing the effect of the high mechanical strength straw resource utilization slow-release carbon source material prepared in Example 1 on nitrate removal over different periods of 20 days; Figure 1 (b) A graph showing the effect of the slow-release carbon source material prepared in Comparative Example 1 on nitrate removal over different periods of 20 days;

[0068] Figure 2(a) The accumulation of nitrite concentration during the removal of nitrate using the high mechanical strength slow-release carbon source material prepared in Example 1 during different 20-day cycles; Figure 2 (b) The accumulation of nitrite concentration during the removal of nitrate using the slow-release carbon source material prepared in Comparative Example 1 over different periods of 20 days;

[0069] Figure 3 (a) The COD concentration of the effluent during the removal of nitrates using the high mechanical strength slow-release carbon source material prepared in Example 1 over different periods of 20 days; Figure 3 (b) The COD concentration in the effluent during the removal of nitrate using the slow-release carbon source material prepared in Comparative Example 1 over different periods of 20 days.

[0070] from Figure 1 , 2 and Figure 3 It can be seen that the high mechanical strength straw resource-based slow-release carbon source material prepared in Example 1 has a good effect on nitrate removal. During the experimental period, the removal rate of nitrates of different concentrations by the graphene slow-release carbon source group reached more than 83%, which is more than 5% higher than the zero-valent iron slow-release carbon source group and existing slow-release carbon sources. Furthermore, during the process of microbial domestication and stabilization, after the denitrification performance of the reactor was gradually activated, the removal rate of nitrates of different concentrations by the graphene slow-release carbon source group approached 100%, while the accumulation of nitrite was also reduced. The concentrations were low, consistently below 0.4 mg / L across all cycles, indicating that the slow-release carbon source could provide sufficient electron donors for the entire denitrification process, ensuring carbon supply. Simultaneously, the effluent COD showed a gradual decreasing trend, with the final effluent COD value generally dropping below 100 mg / L, and in some cases below 50 mg / L, meeting the Class A effluent requirements. Furthermore, the effluent COD continued to decline, suggesting that the slow-release carbon source prepared in this invention will not cause secondary pollution during wastewater treatment once carbon source release stabilizes.

[0071] Figure 4 The images show the morphology of the high mechanical strength slow-release carbon source material prepared in Example 1 before and after soaking. (a) is before soaking, and (b) is after soaking for 20 days.

[0072] Figure 5 SEM images of the high mechanical strength straw resource utilization slow-release carbon source material prepared in Example 1 before and after soaking, (a) before soaking, (b) after soaking for 20 days;

[0073] Figure 6 SEM images of the slow-release carbon source material prepared in Example 3 before and after soaking: (a) before soaking, (b) after soaking for 20 days.

[0074] Figure 7 Example 1 describes the high mechanical strength slow-release carbon source material for straw resource utilization and its soaking process.

[0075] from Figure 4 , 5 6 and Figure 7 It can be seen that the high mechanical strength straw resource-based slow-release carbon source materials prepared in Example 1 can all maintain a good morphological structure. Therefore, the high mechanical strength straw resource-based slow-release carbon source materials prepared in this invention can maintain good impact resistance and have good mechanical strength.

[0076] Figure 8 The two figures on the left show the BET spectra, pore size distribution, and pore volume analysis of the high mechanical strength straw resource-based slow-release carbon source material prepared in Example 1 before and after nitrate removal; Figure 8 The two figures on the right show the BET spectra, pore size distribution, and pore volume analysis of the slow-release carbon source material prepared in Example 1 before and after nitrate removal.

[0077] Figure 9 The graph shows the surface area analysis of the BET spectrum. In the graph, 1 and 2 are the high mechanical strength straw resource recovery slow-release carbon source materials prepared in Example 1 before and after nitrate removal, and 3 and 4 are the slow-release carbon source materials prepared in Control Example 1 before and after nitrate removal.

[0078] from Figure 8 and Figure 9 It can be seen that the slow-release carbon source material with added graphene gradually has a larger specific surface area than the slow-release carbon source material with added nano-zero valent iron during the experiment, and the pore size distribution is more uniform and the pore volume is larger, which can provide more active surface and is beneficial to the reactivity of the material.

[0079] Figure 10 For XRD spectrum analysis, 3 and 4 in the figure are the high mechanical strength straw resource utilization slow-release carbon source materials prepared in Example 1 before and after nitrate removal, and 1 and 2 are the slow-release carbon source materials prepared in Control Example 1 before and after nitrate removal.

[0080] Figure 11 XPS spectra of the high mechanical strength slow-release carbon source material prepared in Example 1 before and after nitrate removal are shown. The two images on the left are before soaking, and the two images on the right are after soaking for 20 days.

[0081] Figure 12 XPS spectra of the slow-release carbon source material prepared in Control Example 1 before and after nitrate removal are shown. The two images on the left are before soaking, and the two images on the right are after soaking for 20 days.

[0082] Figure 13The figures are FTIR images, where 1 and 2 are the slow-release carbon source materials prepared in Comparative Example 1, and 3 and 4 are the high mechanical strength slow-release carbon source materials from straw resources prepared in Example 1.

[0083] from Figures 10-13 It can be seen that the soaking process did not significantly affect the crystal structure and chemical composition of the slow-release carbon source material, proving that the slow-release carbon source material has high chemical stability and good resistance to dissolution and corrosion.

Claims

1. A method for preparing a high-mechanical-strength, slow-release carbon source material from straw resources, characterized in that... The preparation method is specifically carried out according to the following steps: I. Preparation of straw powder: The straw is washed, then soaked in NaOH solution for 3-5 hours, taken out and dried, and crushed into powder to obtain pretreated straw powder. The mass fraction of the NaOH solution mentioned in step one is 1%~4%; II. Preparation of crosslinking agent solution: Polyvinyl alcohol and sodium alginate were added to distilled water and heated and stirred in a water bath at 90-95°C for a period of time until the polyvinyl alcohol and sodium alginate were completely dissolved. The solution was then cooled at room temperature for a period of time to obtain a crosslinking agent solution. The mass-to-volume ratio of polyvinyl alcohol, sodium alginate, and deionized water in step two is (8g~16):(1g~2g):(100mL~200mL); III. Preparation of slow-release carbon source materials: Add attapulgite to the crosslinking agent solution, then add pretreated straw powder, synergistic components and sugarcane molasses, mix and extrude into spherical particles to obtain small spheres of the mixture, then soak them in a saturated boric acid solution of CaCl2 for 24h~48h, take them out, dry and sterilize them, and put them into perforated acrylic spheres. The preparation of high mechanical strength straw resource utilization slow-release carbon source material is completed. The synergistic component mentioned in step three is graphene; the mass ratio of the synergistic component mentioned in step three to the pretreated straw powder is 1:4; the volume ratio of sugarcane molasses to crosslinking agent solution mentioned in step three is (0.5mL~2mL):40mL; The mass ratio of attapulgite clay to the volume ratio of the crosslinking agent solution in step three is (1g~4g):(2mL~8mL); The amount of straw powder added in step three is 2% to 10% of the mass of the crosslinking agent solution.

2. The method for preparing a high mechanical strength slow-release carbon source material from straw resources according to claim 1, characterized in that... The drying temperature in step one is 80℃, and the drying time is 30h~36h.

3. The method for preparing a high mechanical strength slow-release carbon source material from straw resource utilization according to claim 1, characterized in that... The pretreated straw powder described in step one has a particle size of 300-500 mesh.

4. The method for preparing a high mechanical strength slow-release carbon source material from straw resources according to claim 1, characterized in that... The heating and stirring time in step two is 4h~6h; the cooling time at room temperature in step two is 10h~12h.

5. The method for preparing a high mechanical strength slow-release carbon source material from straw resources according to claim 1, characterized in that... The particle size of the high mechanical strength straw resource-based slow-release carbon source material mentioned in step three is 2 mm to 3 mm; the saturated boric acid solution of CaCl2 mentioned in step three refers to the solution of CaCl2 obtained by dissolving CaCl2 in saturated boric acid solution, wherein the mass fraction of CaCl2 is 4%; the drying temperature mentioned in step three is 80℃ to 100℃, and the drying time is 10 h to 14 h.

6. The method for preparing a high mechanical strength slow-release carbon source material from straw resource utilization according to claim 1, characterized in that... The sterilization described in step three is high-pressure steam sterilization; the perforated acrylic ball described in step three consists of two semicircles with a diameter of 2cm and a snap fastener, with five holes of 0.5mm to 1.0mm in diameter on each side.

7. The application of a high-mechanical-strength, slow-release carbon source material from straw resource utilization prepared by the method described in claim 1, characterized in that... A high-mechanical-strength, slow-release carbon source material from straw is applied in the microbial remediation of polluted water bodies.

8. The application of a high-mechanical-strength, slow-release carbon source material from straw resource utilization prepared by the method according to claim 1, characterized in that... A high-mechanical-strength, slow-release carbon source material derived from straw is added to polluted water to act as an electron donor to stimulate microorganisms to metabolize pollutants. The dosage of the high-mechanical-strength, slow-release carbon source material is 83 g / L to 100 g / L. The pollutants in the polluted water are nitrate pollutants. The microorganisms are activated sludge from a secondary sedimentation tank.

Images