A double-metal modified biochar composite material for relieving synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids, and a preparation method and application thereof
By modifying biochar with FeCl3 and calcium salts, nano-Fe3O4 particles are loaded onto the surface of biochar and Ca2+ is introduced to construct a conductive network. This solves the problem of synergistic inhibition of ammonia nitrogen and long-chain fatty acids in the anaerobic digestion of high-oil and high-nitrogen waste, increases methane production, and simplifies the operation. It is suitable for anaerobic digestion of kitchen waste slurry.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGDONG UNIV OF TECH
- Filing Date
- 2026-04-14
- Publication Date
- 2026-07-07
AI Technical Summary
When treating high-oil and high-nitrogen organic waste, existing technologies face the problem of synergistic inhibition of ammonia nitrogen and long-chain fatty acids in anaerobic digestion systems, leading to reduced methane production. Furthermore, existing solutions are costly, have unstable effects, and are difficult to apply on a large scale.
FeCl3 and calcium salts were used to modify biochar. By loading nano-Fe3O4 particles on the surface of biochar in situ and introducing Ca2+ sites, a conductive network was constructed to enhance direct electron transfer, adsorb or complex Ca2+ to reduce the toxicity of long-chain fatty acids, and promote methane generation.
It significantly increases methane yield and conversion rate, simplifies operation, reduces costs, is suitable for industrial production, is applicable to the anaerobic digestion of high-oil and high-nitrogen organic waste, and the material can be magnetically recycled.
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Figure CN122344002A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of biochar composite materials and anaerobic biological treatment of organic waste, specifically to a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids, its preparation method and application, and particularly to its application in the anaerobic digestion treatment of organic waste. Background Technology
[0002] Organic waste such as kitchen waste, livestock and poultry manure, and agricultural straw have been widely used in anaerobic digestion. Anaerobic digestion is considered one of the core technologies in organic waste treatment, playing an irreplaceable role, especially in resource utilization and energy recovery. This technology utilizes anaerobic microorganisms under anaerobic conditions to gradually decompose organic waste such as kitchen waste, livestock and poultry manure, slaughterhouse waste, and agricultural straw, ultimately converting them into biogas (mainly methane) and stable residues, achieving the dual goals of "turning waste into energy" and "turning waste into fertilizer" through resource utilization.
[0003] Existing technologies for treating high-oil, high-nitrogen organic waste with high methane production potential, such as food waste, livestock and poultry manure, and slaughterhouse waste, often face a dual problem of inhibiting methane production in anaerobic digestion systems: Nitrogenous organic matter can be converted into ammonia nitrogen during anaerobic digestion, and high concentrations of ammonia nitrogen are toxic to methanogens, inhibiting their metabolic activity and leading to the accumulation of volatile fatty acids (VFAs), thus reducing methane production; Long-chain fatty acids (LCFAs) produced during oil degradation are easily adsorbed onto the surface of anaerobic microbial cells, and high concentrations of LCFAs are toxic to anaerobic microorganisms. LCFAs encapsulate microorganisms, reducing material transport efficiency and thus inhibiting the anaerobic digestion process of methane production. High ammonia nitrogen conditions exacerbate the inhibitory effect of LCFAs. Current research has confirmed that ammonia nitrogen and long-chain fatty acids have a synergistic inhibitory effect, significantly reducing methane production.
[0004] Traditional solutions to the dual inhibition of methane production in anaerobic digestion systems include dilution, co-digestion, addition of trace elements, and addition of conductive materials. However, dilution and co-digestion are complex, energy-intensive, and difficult to completely eliminate inhibition. Adding trace elements suffers from low bioavailability, difficulty in dosage control, and limited functionality. Adding conductive materials has become a research hotspot in recent years; however, ordinary biochar is easily inactivated by LCFA encapsulation, offering limited relief from LCFA inhibition, and its low content of surface-active functional groups results in unstable direct interspecies electron transfer (DIET) promotion. Conductive materials such as carbon cloth and graphene are costly and difficult to apply on a large scale. In summary, existing technologies are mostly designed for single inhibition types (LCFA inhibition or high ammonia nitrogen inhibition), lacking a systematic solution for the practical situation of coexisting dual inhibition of LCFA and high ammonia nitrogen. Summary of the Invention
[0005] To overcome the shortcomings of the prior art, the first objective of this invention is to provide a method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids. This preparation method is simple to operate, has low energy consumption, mild conditions, low cost, and is easy to industrialize. Moreover, the prepared bimetallic modified biochar composite material can significantly alleviate the synergistic inhibition of ammonia nitrogen and LCFA, and improve methane yield and methane conversion rate.
[0006] To overcome the shortcomings of the prior art, the second objective of this invention is to provide a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids. This bimetallic modified biochar composite material can significantly alleviate the synergistic inhibition of ammonia nitrogen and LCFA, thereby increasing methane yield and methane conversion rate.
[0007] The third objective of this invention is to provide an application of a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids in the anaerobic digestion treatment of organic waste.
[0008] To achieve the first objective of the invention, the technical solution adopted by the present invention is as follows:
[0009] This invention provides a method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids, comprising the following steps:
[0010] A method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids includes the following steps:
[0011] S1. Preparation of biochar: The dried fruit shells are pyrolyzed at high temperature in a tube furnace under a nitrogen atmosphere, cooled, and ground to obtain biochar.
[0012] S2, Fe3O4 modification: FeCl3 is dissolved in ethylene glycol, then sodium acetate is added and stirred, followed by the biochar obtained in step S1. After stirring, a mixture is obtained. The mixture is heated in a reactor and then filtered, washed and dried to obtain Fe3O4 modified biochar.
[0013] S3, Ca modification: The Fe3O4 modified biochar and calcium salt solution obtained in step S2 are added to a container and then placed in a shaker for reaction under oscillation conditions. After filtration and drying, the bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids is obtained.
[0014] This invention discloses a method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids. The method uses FeCl3 as the iron source and ethylene glycol as the solvent and reducing agent. During the heating reaction, nano-Fe3O4 particles are in situ loaded onto the surface of the biochar. Subsequently, the Fe3O4-modified biochar is reacted with a calcium salt solution under oscillating conditions, introducing active Ca2+ into the surface and pores of the Fe3O4-modified biochar. 2+ Sites. A bimetallic modified biochar composite material, prepared by modifying biochar with Fe3O4 and Ca, possesses abundant pore structure, functional groups, and metal active sites. These three elements work together to significantly alleviate the synergistic inhibition of ammonia nitrogen and LCFA, thereby increasing methane yield and methane conversion rate. Specifically, the Ca adsorbed or complexed sites in the bimetallic modified biochar composite material... 2+ Fe3O4 can reduce the toxicity of LCFA through saponification, while it can enhance direct interspecies electron transport (DIET) and improve energy utilization efficiency. Fe3O4 and Ca... 2+ The two work together to synergistically promote LCFA degradation and accelerate methane formation.
[0015] In the Fe3O4 modification process, ethylene glycol plays multiple roles: on the one hand, it acts as a solvent to dissolve FeCl3; on the other hand, it acts as a reducing agent to remove Fe from FeCl3. 3+ Partially reduced to Fe 2+ Furthermore, the high viscosity of ethylene glycol is utilized to limit the diffusion and aggregation of Fe3O4 crystal nuclei, thereby obtaining uniform and fine Fe3O4 nanoparticles. Upon addition of sodium acetate, sodium acetate (CH3COONa) slowly hydrolyzes in ethylene glycol to produce OH-. - , making Fe 3+ with Fe 2+ Co-precipitation occurs at a ratio of 2:1, which allows Fe3O4 crystal nuclei to grow slowly and uniformly, generating small-particle-size, high-purity nano-Fe3O4 on the surface and within the pores of biochar, thus completing the loading of nano-Fe3O4 onto the biochar.
[0016] In the Fe3O4 modification step, FeCl3 is used as a trivalent iron salt. Compared with ferric nitrate and ferric sulfate, this avoids the possibility of corrosion of equipment and alteration of biochar surface properties caused by the use of strongly acidic ferric nitrate solution. It also avoids the possibility of clogging some pores of biochar and reducing the specific surface area of biochar caused by the use of ferric sulfate.
[0017] In the process of Ca modification, the Ca in the calcium salt solution 2+ Electrostatic adsorption, surface complexation, and ion exchange occur between Ca and the oxygen-containing functional groups on the surface of Fe3O4-modified biochar. 2+The calcium salt was loaded onto Fe3O4-modified biochar. Furthermore, the reaction of Fe3O4-modified biochar with calcium salt solution under shaking conditions promoted the growth of Ca2+. 2+ The biochar is brought into full contact with Fe3O4-modified biochar to complete the adsorption and complexation reactions, and then the unattached free Ca is removed by filtration. 2+ And by drying to remove moisture and the adhering Ca 2+ It is fixed in a stable form (such as surface complex or CaCl2 crystal) on the surface and in the pores of Fe3O4 modified biochar.
[0018] Furthermore, in step S1, the fruit shell includes at least one of coconut shell, walnut shell, olive shell, peach shell, or palm shell.
[0019] Furthermore, in step S1, the temperature of the high-temperature pyrolysis is 320℃~380℃, and the time of the high-temperature pyrolysis is 2.5h~3.5h;
[0020] The biochar obtained after grinding has a particle size of 4 mesh to 20 mesh.
[0021] Furthermore, in step S2, the mass-to-volume ratio of FeCl3, ethylene glycol, sodium acetate, and biochar is (1~4) g : (80~120) mL : (5~8) g : (0.5~2) g.
[0022] Furthermore, in step S2, the temperature of the heating reaction is 180℃~220℃, and the heating reaction time is 6h~8h.
[0023] Further, in step S2, FeCl3 is dissolved in ethylene glycol by stirring, then sodium acetate is added and stirred for 30-40 minutes, followed by the addition of biochar prepared in step S1, and stirring for 10-15 minutes to obtain a mixture; and / or
[0024] The washing process involves first washing 2-3 times with anhydrous ethanol, followed by washing 2-3 times with ultrapure water. The use of anhydrous ethanol and ultrapure water removes unreacted reagents and impurities. Finally, drying yields stable Fe3O4-modified biochar. And / or
[0025] The drying process involves drying in an oven at 60℃~65℃ for 12h~24h. This drying process allows nano-Fe3O4 to be more stably loaded onto the surface and within the pores of the biochar.
[0026] Furthermore, in step S3, the mass-to-volume ratio of the Fe3O4 modified biochar to the calcium salt solution is (12~25) g : (250~500) mL; and / or
[0027] The calcium salt solution has a mass percentage concentration of 0.1% to 0.2%; and / or
[0028] The calcium salt solution is a calcium chloride solution. Using calcium chloride solution as the modifying raw material, compared to other calcium salt solutions, results in a lower pH value (CaCl2), a lower likelihood of generating reactive oxygen species, and better solubility, providing effective calcium ions and making it more suitable for the chemical modification of biochar.
[0029] Furthermore, in step S3, the reaction temperature is 28℃~32℃, and the reaction time is 12h~15h; and / or
[0030] The oscillation speed is 130 r / min to 180 r / min; and / or
[0031] The drying process involves drying in an oven at 60℃~65℃ for 12h~24h.
[0032] To achieve the second objective of the invention, the technical solution adopted by the present invention is as follows:
[0033] This invention provides a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids, which is prepared by the above-described preparation method of the bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids.
[0034] To achieve the third objective of the invention, the technical solution adopted by the present invention is as follows:
[0035] This invention provides a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids, or the application of the bimetallic modified biochar composite material prepared by the above-mentioned method for alleviating the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids in the anaerobic digestion treatment of organic waste.
[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0037] (1) A method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids according to the present invention, using FeCl3 as an iron source and ethylene glycol as a solvent and reducing agent, in situ loading of nano-Fe3O4 particles on the surface of biochar during the heating reaction, and then reacting Fe3O4 modified biochar with calcium salt solution under oscillating conditions to introduce active Ca into the surface and pores of Fe3O4 modified biochar. 2+Sites. A bimetallic modified biochar composite material, prepared by modifying biochar with Fe3O4 and Ca, possesses abundant pore structure, functional groups, and metal active sites. These three elements work together to significantly alleviate the synergistic inhibition of ammonia nitrogen and LCFA, thereby increasing methane yield and methane conversion rate. Specifically, the Ca adsorbed or complexed sites in the bimetallic modified biochar composite material... 2+ Fe3O4 can reduce the toxicity of LCFA through saponification, while it can enhance direct interspecies electron transport (DIET) and improve energy utilization efficiency. Fe3O4 and Ca... 2+ The two work together to synergistically promote LCFA degradation and accelerate methane formation.
[0038] (2) The present invention provides a method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids. This method involves modifying biochar with Fe3O4 to construct a conductive network, providing a direct interspecies electron transfer pathway for hydrogen-producing, acetic acid-producing, and methanogenic bacteria in the anaerobic digestion system, effectively accelerating the conversion of volatile fatty acids to methane. Specifically, the uniform loading of Fe3O4 nanoparticles onto the biochar helps construct effective local conductive microregions, promoting electron exchange between microorganisms. Simultaneously, the Fe3O4 surface... 3+ with Fe 2+ Reversible redox pairs, acting as electron shuttles, ensure the efficient operation of the acetic acid-based methanogenesis pathway. This also ensures that acetic acid is the predominant component of volatile fatty acids in the anaerobic digestion system, thereby... Methanosaeta Acetic acid-producing methanogens provide a high-quality substrate, preventing the accumulation of intermediate products such as propionic acid from causing secondary inhibition of the system and further enhancing the conversion rate of acetic acid to methane. Furthermore, the Ca²⁺ on the surface of the bimetallic modified biochar composite material can bind to free long-chain fatty acids, reducing the contact between long-chain fatty acids and microorganisms, thereby effectively inhibiting the adsorption and encapsulation of long-chain fatty acids on the microbial cell surface, thus reducing the mass transfer resistance of microorganisms and ensuring their metabolic activity. Under the synergistic effect of the above multiple mechanisms, the bimetallic modified biochar composite material prepared in this invention, which alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids, can significantly shorten the methanogenesis lag period and system start-up time under the synergistic inhibition of high ammonia nitrogen and high long-chain fatty acids, and improve methane yield and methane conversion rate.
[0039] (3) The preparation method of the bimetallic modified biochar composite material of the present invention, which alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids, has the characteristics of simple operation, low energy consumption, mild conditions, low cost, easy industrial production, and suitable for large-scale production.
[0040] (4) The bimetallic modified biochar composite material of the present invention can alleviate the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids, and can significantly alleviate the synergistic inhibition of ammonia nitrogen and LCFA, and improve methane production and methane conversion rate.
[0041] (5) The application of the bimetallic modified biochar composite material of the present invention, which alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids, is applicable to the anaerobic digestion treatment of organic waste. It is suitable for anaerobic digestion systems using kitchen waste biogas slurry as inoculum, and is particularly suitable for the anaerobic digestion treatment of high-oil and high-nitrogen organic waste. It can significantly shorten the methanogenesis lag period and system start-up time under the synergistic inhibition of high ammonia nitrogen and high long-chain fatty acids, and improve methane production and methane conversion rate. Therefore, the bimetallic modified biochar composite material of the present invention has a promising application prospect.
[0042] (6) The present invention relates to an application of a bimetallic modified biochar composite material that mitigates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids. This bimetallic modified biochar composite material is also magnetic, and after anaerobic digestion, it can be efficiently recovered and recycled through magnetic separation. Considering the characteristic of the kitchen waste biogas slurry inoculation system without added sludge, the porous structure of this bimetallic modified biochar composite material provides a good attachment carrier for functional microorganisms, helping to form a stable biofilm system and enhancing the system's resistance to shock loads. Furthermore, this bimetallic modified biochar composite material has comprehensive advantages in mitigating the toxicity of long-chain fatty acids, maintaining system pH stability, accelerating VFA conversion, promoting electron transfer, and improving the reuse rate of the composite material, providing an efficient, economical, and sustainable functional material solution for anaerobic digestion of organic waste. Attached Figure Description
[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0044] Figure 1 This is a SEM image of the biochar (BC) of Comparative Example 1 of the present invention under 2000x magnification.
[0045] Figure 2 This is a SEM image of the biochar (BC) of Comparative Example 1 of this invention under 5000x magnification.
[0046] Figure 3This is a SEM image of the Fe3O4 modified biochar (Fe3O4-BC) of Comparative Example 2 of this invention under 2000x magnification.
[0047] Figure 4 This is a SEM image of Fe3O4 modified biochar (Fe3O4-BC) of Comparative Example 2 of the present invention under 5000x magnification.
[0048] Figure 5 This is a SEM image of the bimetallic modified biochar composite material (Ca-Fe3O4-BC) of Example 1 of the present invention under 2000x magnification.
[0049] Figure 6 This is a SEM image of the bimetallic modified biochar composite material (Ca-Fe3O4-BC) of Example 1 of the present invention under 5000x magnification.
[0050] Figure 7 The infrared spectra of the materials prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention are shown.
[0051] Figure 8 This shows the cumulative methane production over time for each group of anaerobic digestion systems in this invention.
[0052] Figure 9 This is a graph showing the cumulative methane production results of the anaerobic digestion systems corresponding to each group in this invention.
[0053] Figure 10 The graph shows the detection results of methane production rate of the anaerobic digestion system corresponding to each group of the present invention. Detailed Implementation
[0054] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.
[0055] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. In this invention, the singular forms “a,” “described,” and “the” as used in the embodiments and appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.
[0056] Current regulatory measures for anaerobic digestion inhibition mostly focus on single inhibitory factors, such as ammonia nitrogen inhibition or long-chain fatty acid inhibition alone. Effective methods are lacking to regulate the synergistic inhibitory effect produced when ammonia nitrogen and long-chain fatty acids coexist. Under the dual synergistic inhibition conditions of high ammonia nitrogen (e.g., 5 g / L) and high long-chain fatty acid (e.g., 2.5 g / L oleic acid), traditional anaerobic digestion systems often face the risk of methanogenesis stagnation or even system collapse. The bimetallic modified biochar composite material prepared in this invention can effectively regulate this extreme inhibition scenario through the synergistic effect of multiple mechanisms. Long-chain fatty acids can inhibit β-oxidation by encapsulating microbial cells and reducing transmembrane transport efficiency. The Ca on the surface of the bimetallic modified biochar composite material prepared in this invention… 2+ It can bind to free long-chain fatty acids, reducing their contact with microorganisms, thereby effectively inhibiting the adsorption and encapsulation of long-chain fatty acids on the surface of microbial cells and reducing the mass transfer resistance of microorganisms.
[0057] In this embodiment of the invention, a method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids includes the following steps:
[0058] S1. Preparation of biochar: The dried fruit shells are pyrolyzed at high temperature in a tube furnace under a nitrogen atmosphere, cooled, and ground to obtain biochar.
[0059] S2, Fe3O4 modification: FeCl3 is dissolved in ethylene glycol, then sodium acetate is added and stirred, followed by the biochar obtained in step S1. After stirring, a mixture is obtained. The mixture is heated in a reactor and then filtered, washed and dried to obtain Fe3O4 modified biochar.
[0060] S3, Ca modification: The Fe3O4 modified biochar and calcium salt solution obtained in step S2 are added to a container and then placed in a shaker for reaction under oscillation conditions. After filtration and drying, the bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids is obtained.
[0061] In some embodiments, in step S1, the fruit shell includes at least one of coconut shell, walnut shell, olive shell, peach shell, or palm shell.
[0062] In some embodiments, in step S1, the temperature of the high-temperature pyrolysis is 320℃~380℃, and the time of the high-temperature pyrolysis is 2.5h~3.5h;
[0063] The biochar obtained after grinding has a particle size of 4 mesh to 20 mesh.
[0064] In some embodiments, in step S2, the mass-to-volume ratio of FeCl3, ethylene glycol, sodium acetate and biochar is (1~4) g : (80~120) mL : (5~8) g : (0.5~2) g.
[0065] In some embodiments, in step S2, the temperature of the heating reaction is 180°C to 220°C, and the heating reaction time is 6h to 8h.
[0066] In some embodiments, in step S2, FeCl3 is dissolved in ethylene glycol by stirring, then sodium acetate is added and stirred for 30-40 minutes, followed by the addition of biochar prepared in step S1, and the mixture is stirred for 10-15 minutes to obtain a mixture; and / or
[0067] The washing process involves first washing with anhydrous ethanol 2-3 times, then washing with ultrapure water 2-3 times; and / or
[0068] The drying process involves drying in an oven at 60℃~65℃ for 12h~24h.
[0069] In some embodiments, in step S3, the mass-to-volume ratio of the Fe3O4 modified biochar to the calcium salt solution is (12~25) g: (250~500) mL; and / or
[0070] The calcium salt solution has a mass percentage concentration of 0.1% to 0.2%; and / or
[0071] The calcium salt solution is a calcium chloride solution.
[0072] In some embodiments, in step S3, the reaction temperature is 28°C to 32°C, and the reaction time is 12h to 15h; and / or
[0073] The oscillation speed is 130 r / min to 180 r / min; and / or
[0074] The drying process involves drying in an oven at 60℃~65℃ for 12h~24h.
[0075] In this embodiment of the invention, a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids is prepared by the above-described preparation method of the bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids.
[0076] In this embodiment of the invention, the application of a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids, or the bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids prepared by the above-described method, in the anaerobic digestion treatment of organic waste.
[0077] The following description is based on specific embodiments.
[0078] Example 1
[0079] A method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids includes the following steps:
[0080] S1. Preparation of biochar: 200g of dried coconut shells were placed in a quartz tube and put into a tube furnace. Under a nitrogen atmosphere with a carrier gas flow rate of 0.1L / min, the shells were pyrolyzed at a temperature of 350℃ for 3 hours. After natural cooling, the shells were taken out and ground to a particle size of 10 mesh to obtain biochar.
[0081] S2, Fe3O4 modification: FeCl3 was dissolved in ethylene glycol by stirring, then sodium acetate was added and stirred for 30 min. The biochar prepared in step S1 was then added and stirred for 10 min to obtain a mixture. The mixture was placed in a reaction vessel and reacted at 200℃ for 8 h. After filtration, the mixture was washed three times with anhydrous ethanol and then three times with ultrapure water. Finally, it was dried in an oven at 65℃ for 24 h to obtain Fe3O4 modified biochar. In this example, the mass-volume ratio of FeCl3, ethylene glycol, sodium acetate, and biochar was 2.16 g: 96 mL: 6.56 g: 1.04 g.
[0082] S3, Ca modification: The Fe3O4 modified biochar obtained in step S2 and a 0.15% calcium chloride solution were added to a container, and then placed in a shaker at 30°C and 150 r / min for 12 h. After filtration, the mixture was dried in an oven at 65°C for 24 h to obtain a bimetallic modified biochar composite material (denoted as Ca-Fe3O4-BC) that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids. In this example, the mass-to-volume ratio of Fe3O4 modified biochar to calcium salt solution was 12.5 g: 250 mL.
[0083] The bimetallic modified biochar composite material (Ca-Fe3O4-BC) prepared in Example 1, which synergistically inhibits anaerobic digestion by mitigating ammonia nitrogen and long-chain fatty acids, was subjected to anaerobic digestion experiments. Oleic acid (a type of long-chain fatty acid) was used as the substrate, and ammonium chloride solution was added to simulate a high ammonia nitrogen system. The specific experimental method is as follows:
[0084] A 600 mL fermentation flask was used as the anaerobic reactor. 1.2 g of oleic acid (to achieve a concentration of 2.5 g / L) was added to the fermentation flask as substrate, and sufficient ammonium chloride solution was added to achieve the target ammonia nitrogen concentration of 5 g / L. Then, 2.4 g of bimetallic modified biochar composite material (Ca-Fe3O4-BC, concentration of 5 g / L) was added, followed by 200 mL of anaerobic microbial inoculum, and the volume was brought up to 480 mL with basal anaerobic medium. Three replicates were performed.
[0085] All the above anaerobic reactors were aerated with N2 for 3 minutes, and then placed in a constant temperature water bath at 53±1℃ for incubation until gas was produced, at which point the incubation was stopped.
[0086] The anaerobic reactor described above was connected to a CO2 absorption bottle containing 80 mL of NaOH (3 mol / L) via a silicone tube. The absorption bottle was then connected to a miniature gas flow meter via a silicone tube for CH4 measurement. Finally, the results were detected and recorded using an automated methane potential testing system software (MultiTalent 203, China).
[0087] Example 2
[0088] A method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids includes the following steps:
[0089] S1. Preparation of biochar: 200g of dried walnut shells were placed in a quartz tube and put into a tube furnace. Under a nitrogen atmosphere with a carrier gas flow rate of 0.1L / min, the shells were pyrolyzed at a temperature of 320℃ for 3.5h. After natural cooling, the shells were taken out and ground to a particle size of 4 mesh to obtain biochar.
[0090] S2, Fe3O4 modification: FeCl3 was dissolved in ethylene glycol by stirring, then sodium acetate was added and stirred for 40 min. The biochar prepared in step S1 was then added and stirred for 15 min to obtain a mixture. The mixture was placed in a reaction vessel and reacted at 180℃ for 7 h. After filtration, the mixture was washed twice with anhydrous ethanol and then twice with ultrapure water. Finally, it was dried in an oven at 60℃ for 20 h to obtain Fe3O4 modified biochar. In this example, the mass-volume ratio of FeCl3, ethylene glycol, sodium acetate, and biochar was 1 g: 80 mL: 5 g: 0.5 g.
[0091] S3, Ca modification: The Fe3O4 modified biochar obtained in step S2 and a 0.1% calcium chloride solution were added to a container, and then placed in a shaker at 28°C with an oscillation rate of 180 r / min for 15 h. After filtration, the mixture was dried in an oven at 60°C for 20 h to obtain a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids. In this embodiment, the mass-to-volume ratio of Fe3O4 modified biochar to calcium salt solution was 12 g: 280 mL.
[0092] Example 3
[0093] A method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids includes the following steps:
[0094] S1. Preparation of biochar: 200g of dried olive shells were placed in a quartz tube and then placed in a tube furnace. Under a nitrogen atmosphere with a carrier gas flow rate of 0.1L / min, the shells were pyrolyzed at a temperature of 380℃ for 2.5h. After natural cooling, the shells were taken out and ground to a particle size of 20 mesh to obtain biochar.
[0095] S2, Fe3O4 modification: FeCl3 was dissolved in ethylene glycol by stirring, then sodium acetate was added and stirred for 35 min. The biochar prepared in step S1 was then added and stirred for 12 min to obtain a mixture. The mixture was placed in a reaction vessel and reacted at 220℃ for 6 h. After filtration, the mixture was washed three times with anhydrous ethanol and then three times with ultrapure water. Finally, it was dried in an oven at 62℃ for 16 h to obtain Fe3O4 modified biochar. In this example, the mass-volume ratio of FeCl3, ethylene glycol, sodium acetate, and biochar was 4 g: 120 mL: 8 g: 2 g.
[0096] S3, Ca Modification: The Fe3O4 modified biochar obtained in step S2 and a 0.2% calcium chloride solution were added to a container, and then placed in a shaker at 29°C and 160 r / min for 14 h. After filtration, the mixture was dried in an oven at 62°C for 16 h to obtain a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids. In this example, the mass-to-volume ratio of Fe3O4 modified biochar to calcium salt solution was 25 g: 500 mL.
[0097] Example 4
[0098] A method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids includes the following steps:
[0099] S1. Preparation of biochar: 200g of dried peach shells were placed in a quartz tube and then placed in a tube furnace. Under a nitrogen atmosphere with a carrier gas flow rate of 0.1L / min, the shells were pyrolyzed at a temperature of 330℃ for 3.3h. After natural cooling, the shells were taken out and ground to a particle size of 8 mesh to obtain biochar.
[0100] S2, Fe3O4 modification: FeCl3 was dissolved in ethylene glycol by stirring, then sodium acetate was added and stirred for 32 min. Subsequently, the biochar prepared in step S1 was added and stirred for 11 min to obtain a mixture. The mixture was placed in a reaction vessel and reacted at 190℃ for 7 h. After filtration, it was washed three times with anhydrous ethanol and then three times with ultrapure water. Finally, it was dried in an oven at 64℃ for 12 h to obtain Fe3O4 modified biochar. In this example, the mass-volume ratio of FeCl3, ethylene glycol, sodium acetate and biochar was 2 g:90 mL:6 g:1 g.
[0101] S3, Ca modification: The Fe3O4 modified biochar obtained in step S2 and a 0.13% calcium chloride solution were added to a container, and then placed in a shaker at 31°C with an oscillation rate of 140 r / min for 13 h. After filtration, the mixture was dried in an oven at 64°C for 12 h to obtain a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids. In this example, the mass-to-volume ratio of Fe3O4 modified biochar to calcium salt solution was 15 g: 300 mL.
[0102] Example 5
[0103] A method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids includes the following steps:
[0104] S1. Preparation of biochar: 200g of dried palm shells were placed in a quartz tube and then placed in a tube furnace. Under a nitrogen atmosphere with a carrier gas flow rate of 0.1L / min, the biochar was pyrolyzed at a temperature of 370℃ for 2.8h. After natural cooling, the biochar was taken out and ground to a particle size of 15 mesh to obtain biochar.
[0105] S2, Fe3O4 modification: FeCl3 was dissolved in ethylene glycol by stirring, then sodium acetate was added and stirred for 38 min. The biochar prepared in step S1 was then added and stirred for 14 min to obtain a mixture. The mixture was placed in a reaction vessel and reacted at 210℃ for 6.5 h. After filtration, the mixture was washed three times with anhydrous ethanol and then three times with ultrapure water. Finally, it was dried in an oven at 64℃ for 12 h to obtain Fe3O4 modified biochar. In this example, the mass-volume ratio of FeCl3, ethylene glycol, sodium acetate, and biochar was 3 g: 110 mL: 7 g: 1.5 g.
[0106] S3, Ca modification: The Fe3O4 modified biochar obtained in step S2 and a 0.18% calcium chloride solution were added to a container, and then placed in a shaker at 31°C with an oscillation rate of 140 r / min for 13 h. After filtration, the mixture was dried in an oven at 61°C for 18 h to obtain a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids. In this embodiment, the mass-to-volume ratio of Fe3O4 modified biochar to calcium salt solution was 22 g: 400 mL.
[0107] Example 6
[0108] A method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids includes the following steps:
[0109] S1. Preparation of biochar: 200g of dried coconut shells were placed in a quartz tube and then placed in a tube furnace. Under a nitrogen atmosphere with a carrier gas flow rate of 0.1L / min, the shells were pyrolyzed at a temperature of 340℃ for 3.2h. After natural cooling, the shells were taken out and ground to a particle size of 18 mesh to obtain biochar.
[0110] S2, Fe3O4 modification: FeCl3 was dissolved in ethylene glycol by stirring, then sodium acetate was added and stirred for 36 min. The biochar prepared in step S1 was then added and stirred for 11 min to obtain a mixture. The mixture was placed in a reaction vessel and reacted at 205℃ for 7.5 h. After filtration, the mixture was washed three times with anhydrous ethanol and then three times with ultrapure water. Finally, it was dried in an oven at 62℃ for 22 h to obtain Fe3O4 modified biochar. In this example, the mass-volume ratio of FeCl3, ethylene glycol, sodium acetate, and biochar was 2.5 g: 100 mL: 6.5 g: 1.3 g.
[0111] S3, Ca modification: The Fe3O4 modified biochar obtained in step S2 and a 0.14% calcium chloride solution were added to a container, and then placed in a shaker at 30°C and 160 r / min for 12.5 h. After filtration, the mixture was dried in an oven at 63°C for 22 h to obtain a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids. In this example, the mass-to-volume ratio of Fe3O4 modified biochar to calcium salt solution was 20 g: 450 mL.
[0112] Example 7
[0113] Application of any one of the bimetallic modified biochar composite materials that alleviate the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids in the anaerobic digestion treatment of organic waste in Examples 1 to 6.
[0114] Comparative Example 1
[0115] A method for preparing biochar, which differs from Example 1 in that only step S1 of Example 1 is performed to obtain biochar (denoted as BC).
[0116] The biochar (BC) prepared in Comparative Example 1 was subjected to an anaerobic digestion experiment. The difference between this experiment and that in Example 1 was that the biochar (BC) of Comparative Example 1 was used instead of the bimetallic modified biochar composite material (Ca-Fe3O4-BC) of Example 1. All other experimental methods were the same as in Example 1.
[0117] Comparative Example 2
[0118] A method for preparing Fe3O4 modified biochar, the difference between this method and Example 1 is that only steps S1 and S2 of Example 1 are performed to obtain Fe3O4 modified biochar (denoted as Fe3O4-BC).
[0119] Anaerobic digestion experiments were conducted on the Fe3O4 modified biochar (denoted as Fe3O4-BC) prepared in Comparative Example 2. The difference between this experimental method and that in Example 1 was that the Fe3O4 modified biochar (denoted as Fe3O4-BC) of Comparative Example 2 was used instead of the bimetallic modified biochar composite material (Ca-Fe3O4-BC) of Example 1. All other experimental methods were the same as in Example 1.
[0120] Comparative Example 3
[0121] The difference between this comparative example and Example 1 is that, during the anaerobic digestion experiment, the bimetallic modified biochar composite material (Ca-Fe3O4-BC) was not added, and the added ammonium chloride solution achieved the target ammonia nitrogen concentration of 2.5 g / L. All other experimental methods were the same as in Example 1.
[0122] Comparative Example 4
[0123] The difference between this comparative example and Example 1 is that the bimetallic modified biochar composite material (Ca-Fe3O4-BC) was not added during the anaerobic digestion experiment. All other experimental methods were the same as in Example 1.
[0124] Structural morphology characterization
[0125] (I) Morphological characterization by scanning electron microscopy
[0126] The bimetallic modified biochar composite material (Ca-Fe3O4-BC) of Example 1, the biochar (BC) of Comparative Example 1, and the Fe3O4 modified biochar (Fe3O4-BC) of Comparative Example 2 were characterized by scanning electron microscopy (SEM). The SEM image of the biochar (BC) of Comparative Example 1 is shown below. Figure 1 and Figure 2As shown. The SEM image of Fe3O4-modified biochar (Fe3O4-BC) from Comparative Example 2 is shown below. Figure 3 and Figure 4 As shown. The SEM image of the bimetallic modified biochar composite material (Ca-Fe3O4-BC) of Example 1 is shown below. Figure 5 and Figure 6 As shown.
[0127] Depend on Figure 1 and Figure 2 As can be seen, the BC surface of Comparative Example 1 exhibits a porous skeletal structure, with a relatively smooth surface and an irregular honeycomb-like pore structure. There are no obvious particles attached, and the overall structure shows the carbonaceous morphology characteristics unique to low-temperature pyrolysis carbon.
[0128] Depend on Figure 3 and Figure 4 As can be seen, a large number of spherical nanoparticles are uniformly attached to the surface and pores of Fe3O4-BC in Comparative Example 2. The particles are evenly distributed. The attachment of a large number of Fe3O4 nanoparticles increases the external specific surface area of biochar and increases the active sites of the material. At the same time, some of these Fe3O4 nanoparticles also fill the pores of the microporous structure of biochar.
[0129] Depend on Figure 5 and Figure 6 As can be seen, the Ca-Fe3O4-BC of Example 1 of this invention has a higher surface roughness, and the carbon surface and pores are covered with unevenly distributed particles and coatings. This morphological feature is conducive to the attachment of anaerobic microorganisms and the formation of biofilms, thereby enhancing the shock load resistance of the anaerobic digestion system. Compared with Fe3O4-BC, the number of Fe3O4 nanoparticles is significantly reduced, the distribution is uneven, and local aggregation is observed. The particle morphology is mainly spherical, with some irregular shapes. This indicates that the CaCl2 modification process may have eluted or reorganized some Fe3O4 particles and introduced calcium-containing substances into the carbon surface and pores. This process may have opened some blocked pores and formed a new composite structure.
[0130] (II) Infrared spectroscopy analysis
[0131] The bimetallic modified biochar composite material (Ca-Fe3O4-BC) of Example 1, the biochar (BC) of Comparative Example 1, and the Fe3O4 modified biochar (Fe3O4-BC) of Comparative Example 2 were analyzed by infrared spectroscopy. The infrared spectra are shown below. Figure 7 As shown.
[0132] Depend on Figure 7 As can be seen, surface functional groups such as C–H, O–H, and C=C were detected in BC of Comparative Example 1. Fe3O4-BC of Comparative Example 2 significantly increased the types and numbers of oxygen-containing functional groups through the loading of nano-Fe3O4, with new Fe–OH and CO32- groups appearing.2- The presence of characteristic absorption peaks such as C=O and carboxylates, along with increased intensity of existing C–H, O–H, and C=C peaks, indicates that abundant chemical bonds have formed between nano-Fe3O4 and biochar, effectively enhancing the surface activity of the material. The Ca-Fe3O4-BC in Example 1 retains most of the oxygen-containing functional groups of Fe3O4-BC, with no significant shift in characteristic peak positions and no new impurity peaks, indicating that Ca… 2+ The introduction of [the substance] did not disrupt the main functional group structure of the composite material.
[0133] (III) BET Characterization
[0134] The specific surface area and pore structure of the bimetallic modified biochar composite material (Ca-Fe3O4-BC) of Example 1, the biochar (BC) of Comparative Example 1, and the Fe3O4 modified biochar (Fe3O4-BC) of Comparative Example 2 were characterized by nitrogen adsorption-desorption (BET). The characterization results are shown in Table 1.
[0135] Table 1. BET characterization results of samples from Example 1 and Comparative Examples 1-2
[0136]
[0137] As shown in Table 1, the specific surface area of Ca-Fe3O4-BC in Example 1 is 9.04 m². 2 The surface area of Ca-Fe3O4-BC was 5.81 m² / g, which was 27.3% higher than that of Control Example 1 biochar (BC). The total pore volume of Ca-Fe3O4-BC was 0.021 cm³ / g. 3 / g, with an average pore size of 9.24 nm, which is basically consistent with BC's 9.37 nm. This indicates that the calcium modification process did not destroy the material's framework structure. 2+ The main load is on the outer surface and mesopores, and the pore structure is well maintained.
[0138] Experimental Test
[0139] (I) Anaerobic digestion experiment with synergistic inhibition by high ammonia nitrogen and high long-chain fatty acids
[0140] Anaerobic digestion experiments were conducted according to Example 1 and Comparative Examples 1 to 4, and methane production and methane gas production rate were measured. Specifically, the cumulative methane production was measured from the start of gas production in the anaerobic reactor until day 65 of gas production, as shown below. Figure 8 and Figure 9 As shown. Additionally, the detection results of the methane production rate, as shown... Figure 10 As shown.
[0141] The anaerobic digestion systems and their cumulative methane production for Examples 1, 1 to 4 are shown in Table 2 below.
[0142] Table 2. Anaerobic digestion systems and their cumulative methane production for each group.
[0143]
[0144] Depend on Figures 8 to 10 As shown in Table 2, the anaerobic digestion experiment using the bimetallic modified biochar composite material (Ca-Fe3O4-BC) of Example 1 significantly shortened the methanogenesis lag period under high ammonia nitrogen inhibition, and increased methane yield and gas production rate. The bimetallic modified biochar composite material (Ca-Fe3O4-BC) of Example 1, especially compared to the Fe3O4 modified biochar (Fe3O4-BC) of Comparative Example 2, showed a more significant reduction in the methanogenesis lag period and a marked increase in yield. This indicates that the Ca²⁺ on the surface of the bimetallic modified biochar composite material (Ca-Fe3O4-BC) of this invention can bind with free oleic acid, reducing the contact between oleic acid and anaerobic microorganisms, thereby effectively inhibiting the adsorption and encapsulation of oleic acid on the surface of anaerobic microbial cells, thus reducing the mass transfer resistance of microorganisms. Therefore, Fe3O4 and Ca²⁺ can bind with free oleic acid, reducing the contact between oleic acid and anaerobic microorganisms, and effectively inhibiting the adsorption and encapsulation of oleic acid on the surface of anaerobic microbial cells, thereby reducing the mass transfer resistance of microorganisms. 2+ The two work together to synergistically promote oleic acid degradation, accelerate methane formation, and increase methane production.
[0145] Furthermore, the methane yield in the anaerobic digestion experiment using the bimetallic modified biochar composite material (Ca-Fe3O4-BC) of Example 1 was 892.78 mL, which is an increase of 115.0% compared to Comparative Example 1 (BC), an increase of 20.3% compared to Comparative Example 2 (Fe3O4-BC), an increase of 22.7% compared to Comparative Example 3 (without any biochar and under low ammonia nitrogen conditions), and an increase of 98.6% compared to Comparative Example 4 (without any biochar and under high ammonia nitrogen conditions). Therefore, this demonstrates that the bimetallic modified biochar composite material prepared in this invention can significantly improve methane yield.
[0146] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids, characterized in that, Includes the following steps: S1. Preparation of biochar: The dried fruit shells are pyrolyzed at high temperature in a tube furnace under a nitrogen atmosphere, cooled, and ground to obtain biochar. S2, Fe3O4 modification: FeCl3 is dissolved in ethylene glycol, then sodium acetate is added and stirred, followed by the biochar obtained in step S1. After stirring, a mixture is obtained. The mixture is heated in a reactor and then filtered, washed and dried to obtain Fe3O4 modified biochar. S3, Ca modification: The Fe3O4 modified biochar and calcium salt solution obtained in step S2 are added to a container and then placed in a shaker for reaction under oscillation conditions. After filtration and drying, the bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids is obtained.
2. The preparation method of the bimetallic modified biochar composite material for mitigating the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids as described in claim 1, characterized in that, In step S1, the fruit shell includes at least one of coconut shell, walnut shell, olive shell, peach shell, or palm shell.
3. The preparation method of the bimetallic modified biochar composite material for mitigating the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids as described in claim 1, characterized in that, In step S1, the temperature of the high-temperature pyrolysis is 320℃~380℃, and the time of the high-temperature pyrolysis is 2.5h~3.5h; The biochar obtained after grinding has a particle size of 4 mesh to 20 mesh.
4. The preparation method of the bimetallic modified biochar composite material for mitigating the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids as described in claim 1, characterized in that, In step S2, the mass-to-volume ratio of FeCl3, ethylene glycol, sodium acetate and biochar is (1~4) g : (80~120) mL : (5~8) g : (0.5~2) g.
5. The preparation method of the bimetallic modified biochar composite material for mitigating the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids as described in claim 1, characterized in that, In step S2, the temperature of the heating reaction is 180℃~220℃, and the heating reaction time is 6h~8h.
6. The method for preparing a bimetallic modified biochar composite material for mitigating the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids as described in claim 1, characterized in that, In step S2, FeCl3 is dissolved in ethylene glycol by stirring, then sodium acetate is added and stirred for 30-40 minutes. Subsequently, the biochar prepared in step S1 is added, and the mixture is stirred for 10-15 minutes to obtain a mixture; and / or The washing process involves first washing with anhydrous ethanol 2-3 times, then washing with ultrapure water 2-3 times; and / or The drying process involves drying in an oven at 60℃~65℃ for 12h~24h.
7. The preparation method of the bimetallic modified biochar composite material for mitigating the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids as described in claim 1, characterized in that, In step S3, the mass-to-volume ratio of the Fe3O4 modified biochar to the calcium salt solution is (12~25) g : (250~500) mL; and / or The calcium salt solution has a mass percentage concentration of 0.1% to 0.2%; and / or The calcium salt solution is a calcium chloride solution.
8. The method for preparing a bimetallic modified biochar composite material for mitigating the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids as described in claim 1, characterized in that, In step S3, the reaction temperature is 28℃~32℃, and the reaction time is 12h~15h; and / or The oscillation speed is 130 r / min to 180 r / min; and / or The drying process involves drying in an oven at 60℃~65℃ for 12h~24h.
9. A bimetallic modified biochar composite material for mitigating the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids, characterized in that, It is prepared by the method described in any one of claims 1 to 8 for preparing a bimetallic modified biochar composite material that alleviates the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids.
10. The application of the bimetallic modified biochar composite material for mitigating the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids as described in claim 9, or the bimetallic modified biochar composite material for mitigating the synergistic inhibition of anaerobic digestion by ammonia nitrogen and long-chain fatty acids as described in any one of claims 1 to 8, in the anaerobic digestion treatment of organic waste.