Janus interface induced high-efficiency anaerobic digestion method for organic solid waste

Abstract

The application relates to a Janus interface-induced efficient anaerobic digestion method of organic solid waste, which adopts a functional material with Janus characteristics to treat the organic solid waste, and comprises the following steps: uniformly mixing the organic solid waste with the functional material with Janus characteristics to obtain a mixture; adding inoculum to the mixture to obtain an anaerobic system; adjusting the pH of the anaerobic system; blowing the anaerobic digestion reactor by using purging gas until no residual oxygen; and performing anaerobic digestion reaction under a closed condition. Compared with the prior art, the application breaks through the bottleneck problem that the complex structure of the organic solid waste limits the biodegradation, improves the methanogenic performance of the organic solid waste anaerobic digestion, can improve the total amount of the methanogenic of the organic solid waste anaerobic digestion, provides a new idea for efficient resource utilization of the organic solid waste, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic solid waste treatment and resource utilization, and relates to a Janus interface-induced efficient anaerobic digestion method of organic solid waste. BACKGROUND

[0002] With the rapid growth of the world population, the organic solid waste (such as kitchen waste, kitchen garbage, sewage sludge, etc.) generated by human activities is increasing. Organic solid waste is rich in a large amount of perishable organic matter (such as polysaccharide-like, protein-like and lipid-like substances, etc.), and its improper treatment and disposal not only will cause harm to human health, but also will release a large amount of carbon dioxide to exacerbate global warming. Anaerobic digestion technology can not only recover biomass energy (such as methane), but also reduce the emission of greenhouse gases (such as carbon dioxide), and plays an important role in the resource utilization and harmless treatment of organic solid waste. However, organic solid waste is a complex system with multiple components, multiple media and semi-rigidity, and the complex occurrence form of organic matter makes it difficult to be biologically utilized, and the low efficiency of anaerobic biological conversion caused thereby is a key factor limiting the production of methane by anaerobic digestion of organic solid waste.

[0003] At present, a variety of pretreatment methods (including physical, chemical, biological and combined pretreatment) have been developed to solve the problem of difficult degradation of organic matter in organic solid waste, so as to promote the dissolution and hydrolysis of organic matter and improve the anaerobic biodegradability of organic solid waste. For example, patent CN113233727A discloses a method for rapid lysis of excess sludge by composite biological enzyme, patent CN101012096A discloses a method for producing gas by ultrasonic wave enhanced sludge anaerobic digestion, patent CN101524699A discloses a method for improving sludge anaerobic digestion performance by microwave alkali hydrolysis, patent CN104593432A discloses a method for improving methane production of corn straw anaerobic digestion by alkali and salt combined pretreatment, and patent CN115710076A discloses a method and device for producing methane by anaerobic fermentation of sludge pretreated based on free ammonia. Although the above studies can improve the anaerobic biological conversion efficiency of organic solid waste to a certain extent by strengthening the dissolution and hydrolysis of organic matter, the dissolution, hydrolysis and even biodegradation capacity of organic matter in organic solid waste essentially depends on the complex spatial structure of organic solid waste and the physicochemical properties (such as spatial conformation, molecular polarity and molecular size) of organic matter, and the above problems are ignored in the current traditional pretreatment methods, resulting in that it is usually difficult to achieve stable treatment effect for different organic solid waste, and the key barrier of difficult biological utilization of organic solid waste cannot be fundamentally broken through.

[0004] In addition, the problems of additional energy input, continuous supplement of chemicals and secondary pollution in the traditional pretreatment process limit the practical application of the technology.

[0005] Patent CN113501646A discloses a method for strengthening sludge two-phase anaerobic digestion based on catalytic-conductive material coupling. In the sludge two-phase anaerobic digestion system, zirconium metal organic framework material is added to the hydrolysis acidification phase as a catalyst to strengthen the hydrolysis acidification efficiency of complex organic matter in sludge. At the same time, conductive material is added to the methanogenic phase as a conductive medium between mutualistic microorganisms to improve the efficiency of converting hydrolysis acidification products into methane, thereby achieving efficient methanogenesis of complex organic matter in sludge. However, the traditional zirconium metal organic framework material in this patent only serves as a proton transfer network to promote the mutualistic methanation process, and does not fundamentally solve the problem of difficult biodegradation of organic solid waste. The process involved in this patent is complex, and the cost of material addition is high.

[0006] Patent CN110964209A discloses a preparation method of zirconium-based MOF material and a method for improving anaerobic methanogenesis of vinegar residue. The preparation method of zirconium-based MOF material includes the following steps: (1) dissolving ZrOCl·8H2O and H2BDC in DMF and stirring to form a transparent and uniform solution; (2) adding hydrochloric acid and acetic acid as adjusting agents and continuing to stir to obtain a reaction mother liquor; (3) placing the reaction mother liquor in an oven and reacting at 95-105℃ for 2-3h, then transferring the gel to a reaction kettle and continuing to react at 175-185℃ for 2-3h, naturally cooling to 25-40℃, then washing with ethanol by centrifugation, and drying to obtain a white granular product; then the prepared zirconium-based MOF material is used to improve the methanogenesis efficiency in the anaerobic digestion process of vinegar residue. However, the zirconium-based MOF material in this patent is mainly aimed at improving the electron transfer efficiency between mutualistic microorganisms, thereby alleviating the accumulation of a large amount of volatile organic acids and improving the methanogenesis of mutualistic microorganisms in the anaerobic digestion process of vinegar residue. It does not focus on the problem of difficult biodegradation of organic matter caused by the complex physicochemical properties of organic solid waste. SUMMARY

[0007] The purpose of the present application is to overcome at least one of the deficiencies of the prior art and provide a Janus interface induced high-efficiency anaerobic digestion method for organic solid waste. The present application breaks through the bottleneck problem of the complex structure of organic solid waste limiting its biodegradation, improves the methanogenesis performance of organic solid waste, and provides a new idea for the efficient resource utilization of organic solid waste, which has a good application prospect.

[0008] The purpose of the present application can be achieved by the following technical solutions:

[0009] One of the technical solutions of the present application is to provide a Janus interface induced high-efficiency anaerobic digestion method for organic solid waste. The method uses functional materials with Janus characteristics to treat organic solid waste, including the following steps:

[0010] (1) mixing the organic solid waste with the functional material with Janus characteristics uniformly to obtain a mixture;

[0011] (2) adding an inoculum to the mixture to obtain an anaerobic system;

[0012] (3) adjusting the pH of the anaerobic system, and blowing the anaerobic digestion reactor to be free of residual oxygen by blowing gas;

[0013] (4) carrying out the anaerobic digestion reaction under a sealed condition to produce methane.

[0014] It has been shown by previous studies that the main component of the organic solid waste is water (water content > 80%), and the complex organic matter therein mainly exists in a solid state. In the process of anaerobic biological conversion, this “solid-liquid-solid” mode causes a complex spatial structure of the organic solid waste, greatly limiting the biotransformation potential of the organic matter and the mass transfer efficiency and enzymatic reaction rate of the anaerobic biological reaction.

[0015] The catalytic material with Janus characteristics has both hydrophobic and hydrophilic sites, and can restructure the spatial structure of the organic solid waste, reduce the energy barrier of the transformation of the sludge organic matter from a solid state to a liquid state, and directly regulate the physicochemical properties (molecular polarity and spatial conformation) of the solid-state organic matter based on the hydrophobic effect. In addition, the organic matter regulated by the Janus interface can be more efficiently combined with the catalytic sites in the catalytic material, further improving the catalytic decomposition performance of the macromolecular organic matter to small molecular organic matter. In summary, the catalytic material with Janus characteristics improves the biotransformation potential of the complex organic matter itself, and strengthens the mass transfer efficiency and enzymatic reaction efficiency of the anaerobic biological conversion process, thereby realizing the efficient anaerobic biological conversion process of the organic solid waste.

[0016] The present application uses the functional material with Janus characteristics to treat the organic solid waste, restructures the spatial structure of the organic molecules in the organic solid waste, changes the spatial conformation, molecular polarity and molecular size of the organic matter in the solid and liquid phases, improves the anaerobic biological conversion potential of the organic solid waste, and strengthens the mass transfer efficiency and enzymatic reaction efficiency of the anaerobic biological conversion process, thereby realizing the efficient anaerobic digestion and methane production of the organic solid waste.

[0017] Further, the functional material with Janus characteristics in step (1) is a hydrophilic catalytic material with surface hydrophobic modification.

[0018] Further, the hydrophilic catalytic material is a porous metal organic framework material with catalytic decomposition ability to organic matter, including MOF-808, UiO-66 or NU-1000.

[0019] Further, the surface hydrophobic modification is achieved by high-temperature carbonization, specifically, the hydrophilic catalytic material is placed in a heating furnace, heated to a target temperature at a certain heating rate under the condition of protective gas, and then maintained at the target temperature for a period of time, so as to realize the surface hydrophobic modification of the material by pyrolysis of the surface of the hydrophilic catalytic material, and then the material is immediately cooled to room temperature to obtain a functional material with Janus characteristics.

[0020] Further, the protective gas is nitrogen, the heating rate is 5-10℃ / min, the target temperature is 200-400℃, and the maintenance time is 5-10min.

[0021] Further, in step (1), the organic solid waste is selected from one or more of municipal sludge, kitchen waste, kitchen garbage and crop straw, the total solid content (TS) of the organic solid waste is 2.0-5.4%, and the volatile solid content (VS) to total solid content (TS) ratio of the organic solid waste is 43.7-65.5%.

[0022] Further, in step (2), the inoculum includes digestion sludge stably running in an anaerobic digestion reactor, the total solid content of the inoculum is 2.5-4.0%, and the volatile solid content to total solid content ratio of the inoculum is 30.2-50.5%.

[0023] Further, in step (1), the functional material with Janus characteristics and the volatile solid content of the organic solid waste have a mass ratio of 1:(2-4), and in step (2), the volatile solid content of the inoculum and the volatile solid content of the organic solid waste have a mass ratio of 1:(1-3).

[0024] Further, in step (3), the pH regulator is selected from one or both of sodium bicarbonate and sodium hydroxide, the pH is 6.8-7.2, and the purging gas is nitrogen.

[0025] Further, in step (4), the temperature is 35-60℃, and the stirring rate is 80-120r / min.

[0026] As a preferred technical solution, in step (4), the gas production and composition in the anaerobic system are monitored every day during the experiment.

[0027] As a preferred technical solution, in step (4), when the gas production in the anaerobic system is 0mL, the reaction can be stopped.

[0028] Compared with the prior art, the present application has the following advantages:

[0029] (1) The present application first proposes a method of Janus interface-induced efficient anaerobic digestion of organic solid waste to produce methane, which restructures the spatial structure of organic solid waste by using functional materials with Janus characteristics, effectively changes the physicochemical properties (spatial conformation, molecular polarity and molecular size) of solid and liquid organic matter by combining the catalytic performance of the materials, and improves the biocompatibility of organic matter itself;

[0030] (2) The present application breaks through the solid-liquid interface limitation of organic solid waste by restructuring the spatial structure of organic solid waste, improves the mass transfer efficiency and enzymatic reaction efficiency of the anaerobic biological conversion process, and strengthens the anaerobic biological conversion reaction;

[0031] (3) The present application uses functional materials with Janus characteristics in the anaerobic digestion system, which not only fundamentally improves the anaerobic digestion performance of organic solid waste to produce methane, but also provides unlimited opportunities for the sustainable development of future related technologies due to the heterogeneity and recyclable potential of the functional materials. The functional materials can be separated and recycled after the reaction, which is green and environmentally friendly, and has good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The figure is a process schematic diagram of the Janus interface-induced efficient anaerobic digestion method of organic solid waste in the embodiments of the present application;

[0033] Figure 2 The figure is a cumulative methane production comparison chart of the Janus interface-induced efficient anaerobic digestion method of organic solid waste in the embodiments and comparative examples of the present application;

[0034] Figure 3 The figure is a maximum daily methane production comparison chart of the Janus interface-induced efficient anaerobic digestion method of organic solid waste in the embodiments and comparative examples of the present application. DETAILED DESCRIPTION

[0035] The present application will be described in detail below in combination with specific embodiments. The present embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation methods and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0036] The equipment used in each of the following embodiments represents conventional equipment in the art unless otherwise specified; the reagents used represent commercially available products or are prepared by conventional methods in the art unless otherwise specified; and the methods not described in detail in the following embodiments can be realized by conventional experimental methods in the art.

[0037] The organic solid waste matrix used in the examples and comparative examples is municipal sludge (TS = 3.0%, VS / TS = 51.4%), and the inoculum used is the digestion sludge stably operated in the anaerobic digestion reactor (TS = 2.8%, VS / TS = 45.6%), and the batch methanation experiment of anaerobic digestion of organic solid waste is carried out in a serum bottle with a working volume of 500 mL.

[0038] Example 1:

[0039] A functional material with Janus characteristics is prepared by high-temperature carbonization of a hydrophilic catalytic material on the surface, as shown in the following specific steps: Figure 1

[0040] The hydrophilic catalytic material MOF-808 is placed in a tube furnace and heated to a target temperature of 200℃ at a heating rate of 10℃ / min under nitrogen, and then maintained at the target temperature for 10 min to realize surface hydrophobic modification of the material by pyrolysis of the surface of the hydrophilic catalytic material, and then immediately cooled to room temperature to obtain the functional material with Janus characteristics.

[0041] A method for inducing efficient anaerobic digestion of organic solid waste by Janus interface, as shown in the following specific steps: Figure 1

[0042] 311.75g of municipal sludge and 2.40g of functional material with Janus characteristics are added to a serum bottle and mixed evenly, and the mass ratio of the functional material with Janus characteristics to the volatile solids in the municipal sludge is 1:2; then 188.25g of digestion sludge is added, and the mass ratio of the volatile solids in the digestion sludge to the volatile solids in the municipal sludge is 1:2; sodium bicarbonate and sodium hydroxide are used to adjust the pH of the anaerobic system to 7.0, and finally the serum bottle is purged with nitrogen until there is no residual oxygen; the batch methanation experiment is carried out under anaerobic digestion reaction in a closed condition with a stirring rate of 120r / min and a water bath temperature of 55℃, and the reaction is stopped when the gas production in the anaerobic system is 0mL. The gas production and composition in the anaerobic system are monitored every day during the experiment.

[0043] Comparative Example 1:

[0044] An anaerobic digestion method for organic solid waste, which is basically the same as Example 1, except that commercial glass beads are used instead of functional materials with Janus characteristics as the added material in the serum bottle.

[0045] Comparative Example 2:

[0046] ​​An organic solid waste anaerobic digestion method, which is basically the same as example 1, except that the original hydrophilic catalytic material MOF-808 without carbonization treatment is used instead of the functional material with Janus characteristics.

[0047] Example 2:

[0048] A Janus interface induced efficient anaerobic digestion method of organic solid waste, which is basically the same as example 1, except that the target temperature of carbonization in the preparation process of the functional material with Janus characteristics is 250℃.

[0049] Example 3:

[0050] A Janus interface induced efficient anaerobic digestion method of organic solid waste, which is basically the same as example 1, except that the target temperature of carbonization in the preparation process of the functional material with Janus characteristics is 300℃.

[0051] Example 4:

[0052] A Janus interface induced efficient anaerobic digestion method of organic solid waste, which is basically the same as example 1, except that the target temperature of carbonization in the preparation process of the functional material with Janus characteristics is 400℃.

[0053] As shown in Figure 2 , the cumulative methane production of example 1, comparative example 2, example 2, example 3 and example 4 in the anaerobic digestion process is 515.2 mL, 504.9 mL, 519.8 mL, 570.7 mL and 542.4 mL, respectively, which is increased by 24.7%, 22.2%, 25.8%, 38.1% and 31.3% compared with comparative example 1 (413.2 mL), and the surface of the functional material with Janus characteristics can further improve the anaerobic digestion methane production performance of organic solid waste compared with the original hydrophilic catalytic material MOF-808. It is worth noting that the cumulative methane production corresponding to example 3 is the highest, which indicates that when the surface carbonization target temperature of the hydrophilic catalytic material is 300℃, the functional material with Janus characteristics prepared has the best promotion effect on the anaerobic digestion system. This is mainly because with the increase of the carbonization target temperature, the hydrophobic layer on the surface of the hydrophilic catalytic material is gradually formed, and the functional material with Janus characteristics formed can restructure the spatial structure of the organic solid waste, change the physicochemical properties of the complex organic matter, and improve the biotransformation potential of the organic solid waste. However, when the temperature is further increased, the hydrophobic layer on the surface of the catalytic material gradually becomes thicker, the internal hydrophilicity of the material is almost completely eliminated, and the internal pore structure is seriously damaged, which reduces the promotion effect of the functional material on the anaerobic digestion system to some extent.

[0054] AsFigure 3 As shown, the maximum daily methane production of Example 1, Comparative Example 2, Example 2, Example 3 and Example 4 in the anaerobic digestion process were 135.85 mL / d, 134.55 mL / d, 136.57 mL / d, 140.80 mL / d and 138.40 mL / d, respectively, which were increased by 26.16%, 24.95%, 26.83%, 30.76% and 28.53% compared with Comparative Example 1 (107.68 mL / d), further indicating that the functional material with Janus property can improve the methane production performance of organic solid waste in anaerobic digestion.

[0055] The above description of the embodiments is to facilitate the understanding and use of the present application by those skilled in the art. Those skilled in the art can easily make various modifications to the embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present application is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present application without departing from the scope of the present application should be within the protection scope of the present application.

Claims

1. A Janus interface-induced efficient anaerobic digestion method of organic solid waste, characterized in that, The method adopts a functional material with Janus characteristics to treat organic solid waste, comprising the following steps: (1) uniformly mixing the organic solid waste with the functional material with Janus characteristics to obtain a mixture; (2) adding an inoculum to the mixture to obtain an anaerobic system; (3) adjusting the pH of the anaerobic system, and blowing the anaerobic digestion reactor with a sweep gas until no residual oxygen is present; (4) performing anaerobic digestion reaction under a sealed condition; In step (1), the functional material with Janus characteristics is a hydrophilic catalytic material with surface hydrophobic modification; The hydrophilic catalytic material is a porous metal organic framework material MOF-808 with catalytic decomposition ability for organic matter; The surface hydrophobic modification adopts a high-temperature carbonization method.

2. The method according to claim 1, wherein the Janus interface-induced organic solid waste high-efficiency anaerobic digestion method is characterized by, The high-temperature carbonization method specifically comprises: placing the hydrophilic catalytic material in a heating furnace, heating to a target temperature at a certain heating rate under a protective gas condition, maintaining at the target temperature for a period of time, and then immediately cooling the material to room temperature to obtain the functional material with Janus characteristics.

3. The method according to claim 2, wherein the Janus interface induces efficient anaerobic digestion of organic solid waste. The protective gas is nitrogen, the heating rate is 5-10 ℃ / min, the target temperature is 200-400 ℃, and the maintenance time is 5-10 min.

4. The method according to claim 1, wherein the Janus interface-induced anaerobic digestion of organic solid waste is characterized by, In step (1), the organic solid waste is selected from one or more of municipal sludge, kitchen waste, kitchen garbage, and crop straw, the total solid mass content of the organic solid waste is 2.0-5.4%, and the volatile solid content to total solid mass ratio of the organic solid waste is 43.7-65.5%.

5. The method according to claim 1, wherein the Janus interface-induced anaerobic digestion of organic solid waste is characterized by, In step (2), the inoculum includes digestion sludge, the total solid mass content of the inoculum is 2.5-4.0%, and the volatile solid content to total solid mass ratio of the inoculum is 30.2-50.5%.

6. The method according to claim 1, wherein the Janus interface-induced anaerobic digestion of organic solid waste is characterized by, In step (1), the mass ratio of the functional material with Janus characteristics to the volatile solid of the organic solid waste is 1:(2-4), and in step (2), the mass ratio of the volatile solid of the inoculum to the volatile solid of the organic solid waste is 1:(1-3).

7. The method according to claim 1, wherein the Janus interface-induced anaerobic digestion of organic solid waste is characterized by, In step (3), the pH regulator is selected from one or both of sodium bicarbonate and sodium hydroxide, the pH is 6.8-7.2, and the sweep gas is nitrogen.

8. The method according to claim 1, wherein the Janus interface-induced anaerobic digestion of organic solid waste is characterized by, In step (4), the temperature is 35-60 ℃, and the stirring rate is 80-120 r / min.

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