A composite enzyme-carbon black composite material, a preparation method and application thereof

Abstract

This application discloses a composite enzyme-carbon black material, comprising functionalized carbon black, a composite enzyme, and a crosslinking agent; the surface of the functionalized carbon black contains oxygen-containing and nitrogen-containing functional groups. The composite enzyme-carbon black material of this application can effectively inhibit the loss and inactivation of enzymes in high-solids-content dry anaerobic systems, prolonging their hydrolysis cycle; while effectively promoting the continuous transformation of recalcitrant organic components in organic solid waste, it improves the removal efficiency of volatile solids and total solids, mitigates the impact of substrate supply fluctuations in high-solids-content systems on the methanogenesis process, and enables the dry anaerobic digestion process to operate efficiently and stably, providing strong support for the large-scale treatment of high-solids-content waste sludge and other organic solid wastes.

Description

Technical Field

[0001] This application relates to the field of organic solid waste resource utilization technology, specifically to a composite enzyme-carbon black composite material, its preparation method, and its application. Background Technology

[0002] Sludge and kitchen waste, among other high-solids-content organic solid wastes, have great potential for resource recovery, but their complex composition and high treatment difficulty make them suitable for processing. Dry anaerobic digestion, which requires no large-scale dilution, has a high loading capacity, and produces high gas density, is well-suited for treating such wastes. However, the high solids content in dry anaerobic systems leads to poor material flowability and severely limited mass transfer, resulting in slow hydrolysis of large organic molecules, long reaction start-up cycles, and insufficient operational stability. Traditional solutions to these problems lack technical means to simultaneously maintain enzyme stability and continuously improve hydrolysis efficiency under high solids conditions. Therefore, there is an urgent need to develop a stabilization technology that can maintain enzyme activity and continuously enhance organic matter hydrolysis in high-solids-concentration, complex environments. Summary of the Invention

[0003] In view of this, the technical problem to be solved by this application is to provide a composite enzyme-carbon black composite material, its preparation method, and its application. The composite material provided by this application can effectively improve the degradation efficiency of organic matter and methane production in high-solids dry anaerobic digestion systems.

[0004] This application provides a composite enzyme-carbon black composite material, comprising functionalized carbon black, a composite enzyme, and a crosslinking agent; The functionalized carbon black surface contains oxygen-containing functional groups and nitrogen-containing functional groups.

[0005] In some specific implementations, the complex enzyme includes one or more of proteases, cellulases, lysozymes, and phospholipases.

[0006] In some specific implementations, the complex enzyme includes protease and cellulase; The mass ratio of the protease to the cellulase is 0.5 to 2:1.

[0007] In some specific implementations, the oxygen-containing functional group includes one or more of the following: carboxyl, hydroxyl, carbonyl, ether, sulfonic acid, and phosphate groups; The nitrogen-containing functional groups include one or more of primary amino, secondary amino, tertiary amino, quaternary ammonium, amide, and imino groups; The crosslinking agent includes one or more of glutaraldehyde, glyoxal, succinaldehyde, ethylene glycol diglycidyl ether, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC).

[0008] In some specific implementations, the mass ratio of the functionalized carbon black to the composite enzyme is 1:0.02~0.10.

[0009] This application also provides a method for preparing the above-mentioned composite enzyme-carbon black composite material, comprising the following steps: Functionalized carbon black, composite enzyme, and crosslinking agent were reacted to obtain a composite enzyme-carbon black composite material.

[0010] In some specific implementations, the functionalized carbon black is prepared according to the following method: Carbon black is subjected to oxidation and ammoniation treatments in sequence to obtain functionalized carbon black.

[0011] In some specific implementations, the oxidizing agent used in the oxidation treatment includes one or more of ozone, hydrogen peroxide, potassium permanganate, dilute nitric acid, sodium hypochlorite, and peracetic acid. The amination reagent used in the amination treatment includes one or more of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, ethylenediamine, and polyethyleneimine.

[0012] This application also provides a method for dry anaerobic digestion of the above-mentioned composite enzyme-carbon black composite material, comprising adding the composite enzyme-carbon black composite material to organic solid waste for anaerobic fermentation.

[0013] In some specific implementations, the total solids content of organic solid waste in the dry anaerobic digestion is 10% to 30%.

[0014] This application provides a composite enzyme-carbon black material, comprising functionalized carbon black, a composite enzyme, and a crosslinking agent; the surface of the functionalized carbon black contains oxygen-containing and nitrogen-containing functional groups. This application employs a crosslinking reaction to covalently immobilize the composite enzyme on the surface of the functionalized carbon black, constructing a confined immobilization structure capable of spatially constraining enzyme molecules, effectively inhibiting enzyme loss and inactivation in high-solids-content dry anaerobic systems, and prolonging its hydrolysis cycle.

[0015] The composite enzyme-carbon black composite material described in this application can not only effectively promote the continuous transformation of recalcitrant organic components in organic solid waste and improve the removal efficiency of volatile solids and total solids, but also mitigate the impact of substrate supply fluctuations in high solids-content systems on the methanogenesis process, enabling the dry anaerobic digestion process to operate efficiently and stably, and providing strong support for the large-scale treatment of organic solid wastes such as high solids-content residual sludge. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the synthetic route for the immobilized composite enzyme-carbon black composite material of this application. Detailed Implementation

[0017] This application provides a composite enzyme-carbon black material, its preparation method, and its application. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. The methods and applications of this application have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this application to realize and apply the technology of this application.

[0018] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0019] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0020] It should be understood that the order of steps or the sequence of actions is not important as long as this application remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0021] The use of any and all instances or exemplary language such as “e.g.” or “including” herein is merely intended to better illustrate the application and does not constitute a limitation on the scope of the application unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of this application.

[0022] Furthermore, the numerical ranges and parameters used to define this application are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any numerical value inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise explicitly stated, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0023] This application provides a composite enzyme-carbon black composite material, comprising functionalized carbon black, a composite enzyme, and a crosslinking agent; The functionalized carbon black surface contains oxygen-containing functional groups and nitrogen-containing functional groups.

[0024] The composite enzyme-carbon black composite material provided in this application includes functionalized carbon black, the surface of which contains oxygen-containing functional groups and nitrogen-containing functional groups. In some specific implementations, the oxygen-containing functional groups are preferably one or more selected from carboxyl, hydroxyl, carbonyl, ether, sulfonic acid, and phosphate groups, more preferably carboxyl and / or hydroxyl groups. The nitrogen-containing functional groups are preferably one or more selected from primary amino, secondary amino, tertiary amino, quaternary ammonium, amide, and imino groups, more preferably primary amino groups. In some specific implementations, the mass ratio of the functionalized carbon black to the composite enzyme is preferably 1:0.01~0.08, more preferably 1:0.04~0.08.

[0025] The composite enzyme-carbon black composite material provided in this application includes a composite enzyme for promoting the hydrolytic transformation of organic macromolecules in a high-solids-content anaerobic digestion system. The composite enzyme described in this application is covalently fixed to functional groups on the surface of functionalized carbon black through at least two covalent linkage sites and is distributed in a dispersed manner. This ensures that the composite enzyme molecules are stably attached to the carbon black carrier surface in the anaerobic digestion system, effectively inhibiting the migration of the composite enzyme during anaerobic digestion.

[0026] In some specific implementations, the composite enzyme is preferably one or more of protease, cellulase, lysozyme, and phospholipase, more preferably protease and cellulase. In some specific implementations, the mass ratio of the protease to cellulase is preferably 0.5~2:1, more preferably 1:1. The composite enzyme described in this application is simultaneously immobilized on the same functionalized carbon black carrier surface at a predetermined mass ratio, and the total enzyme loading is controlled within a suitable range to ensure both enzyme immobilization effect and substrate accessibility.

[0027] The composite enzyme-carbon black composite material provided in this application includes a crosslinking agent for covalent crosslinking of the composite enzyme and functionalized carbon black. In some specific implementations, the crosslinking agent is preferably one or more selected from glutaraldehyde, glyoxal, succinaldehyde, ethylene glycol diglycidyl ether, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, more preferably glutaraldehyde. In some specific implementations, the mass concentration of the crosslinking agent is preferably 0.1 wt% to 1 wt%, more preferably 0.3 wt% to 0.6 wt%.

[0028] This application also provides a method for preparing the above-mentioned composite enzyme-carbon black composite material, the preparation process of which is described in [reference needed]. Figure 1 , Figure 1 This is a schematic diagram of the synthetic route for the immobilized complex enzyme-carbon black composite material of this application, including the following steps: Functionalized carbon black, composite enzyme, and crosslinking agent were reacted to obtain a composite enzyme-carbon black composite material.

[0029] This application uses functionalized carbon black, a composite enzyme, and a crosslinking agent as raw materials to perform a crosslinking reaction, thereby preparing a composite enzyme-carbon black composite material. The composite enzyme and crosslinking agent are as described above and will not be repeated here. The functionalized carbon black is prepared according to the following method: Carbon black is subjected to oxidation and ammoniation treatments in sequence to obtain functionalized carbon black.

[0030] Specifically, this application first oxidizes the carbon black, causing it to react with an oxidizing agent and introduce oxygen-containing functional groups onto its surface, thereby obtaining surface-modified functionalized carbon black. Subsequently, the functionalized carbon black undergoes ammoniation treatment, reacting with an ammoniation agent to further introduce nitrogen-containing functional groups onto the carbon black surface, resulting in functionalized carbon black. This application does not impose any special restrictions on the source of the carbon black; commercially available raw materials are acceptable. In some specific implementations, the particle size of the carbon black is preferably 30 μm to 100 μm, more preferably 40 μm to 60 μm. The oxygen-containing and nitrogen-containing functional groups are as described above and will not be repeated here.

[0031] In this application, during the oxidation treatment of carbon black, oxygen-containing functional groups are introduced onto the surface of the carbon black using an oxidizing agent to obtain surface-modified functionalized carbon black. Specifically, the carbon black is first dispersed in deionized water and ultrasonically mixed to form a suspension; an oxidizing agent is then added to the suspension for oxidation treatment to obtain functionalized carbon black. In some specific implementations, the mass ratio of carbon black to deionized water is preferably 1:10~30, more preferably 1:15~25; the ultrasonic power is preferably 100 W~500 W, more preferably 200 W~400 W; and the ultrasonic time is preferably 30 min~120 min, more preferably 50 min~70 min.

[0032] This application does not impose any special restrictions on the source of the oxidizing agent; commercially available raw materials are acceptable. In some specific implementations, the oxidizing agent is preferably one or more of ozone, hydrogen peroxide, potassium permanganate, dilute nitric acid, sodium hypochlorite, and peracetic acid, more preferably ozone. In some specific implementations, the concentration of the oxidizing agent is preferably 30 mg / L to 90 mg / L, more preferably 50 mg / L to 70 mg / L. The reaction temperature of the oxidation treatment is preferably 20℃ to 30℃, more preferably 24℃ to 26℃, and the reaction time is preferably 6 h to 10 h, more preferably 7 h to 9 h.

[0033] The oxidation process described in this application is preferably carried out under mechanical stirring conditions, with the stirring speed preferably being 100 rpm to 500 rpm, more preferably 100 rpm to 300 rpm. The oxidation process can control the oxygen content on the carbon black surface, with the oxygen content on the carbon black surface preferably being 15% to 25%, more preferably 15% to 20%.

[0034] In this application, during the ammoniation process, nitrogen-containing functional groups are further introduced onto the surface of carbon black using an ammoniation reagent to enhance the binding ability between the functionalized carbon black and the complex enzyme, thereby stably immobilizing the complex enzyme on the surface of the functionalized carbon black. Specifically, this application first disperses the functionalized carbon black in an organic solvent, then adds the ammoniation reagent to react and obtain the functionalized carbon black. In some specific implementations, the organic solvent is preferably one or more of toluene, acetone, ethanol, isopropanol, xylene, and tetrahydrofuran, more preferably toluene. This application does not have any particular limitation on the dispersion method, as long as the carbon black is dispersed uniformly; ultrasonic dispersion is preferred.

[0035] This application does not impose any special restrictions on the source of the amination reagent; commercially available raw materials are acceptable. In some specific implementations, the amination reagent is preferably one or more of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, ethylenediamine, and polyethyleneimine, more preferably 3-aminopropyltriethoxysilane. In some specific implementations, the mass ratio of carbon black to the amination reagent is preferably 1:2 to 10, more preferably 1:3 to 6.

[0036] In some specific implementations, the ammoniation reaction described in this application is preferably carried out under stirring conditions, with a reaction temperature preferably between 60°C and 90°C, more preferably between 70°C and 90°C, and a reaction time preferably between 6 h and 10 h, more preferably between 7 h and 9 h. The ammoniation process described in this application is a necessary prerequisite for the covalent grafting of enzyme and carbon black. Without ammoniation, the enzyme can only be physically adsorbed onto the carbon black surface, resulting in a significant reduction in both enzyme loading and methane yield. The introduction of nitrogen-containing functional groups plays a crucial role in improving enzyme immobilization efficiency and digestion enhancement.

[0037] This application uses a cross-linking agent to covalently immobilize a complex enzyme on the surface of functionalized carbon black via a cross-linking reaction. Specifically, it includes the following steps: a) Mix functionalized carbon black, weak acid buffer solution and complex enzyme to obtain a premix solution; b) Add the crosslinking agent to the premixed solution to carry out the crosslinking reaction, and obtain the composite enzyme-carbon black composite material.

[0038] This application involves thoroughly mixing functionalized carbon black, a weak acid buffer solution, and a composite enzyme to obtain a premixed solution. In some specific implementations, the weak acid buffer solution is preferably one or more of acetic acid buffer solution, citric acid-sodium citrate buffer solution, potassium hydrogen phthalate-sodium hydroxide buffer solution, and lactic acid-sodium lactate buffer solution, more preferably acetic acid buffer solution. The pH value of the weak acid buffer solution is preferably 4-6, more preferably 4.5-5. In some specific implementations, the mass ratio of the composite enzyme to the functionalized carbon black is 0.02-0.10:1, preferably 0.05-0.10:1. The immobilization efficiency of the composite enzyme on the functionalized carbon black is 70%-80%. In some specific implementations, the mixing is carried out under stirring conditions. This application does not have special limitations on the stirring parameters, as long as the functionalized carbon black, weak acid buffer solution, and composite enzyme are thoroughly and uniformly mixed.

[0039] After obtaining the premixed solution, a crosslinking agent is added to the premixed solution to carry out a crosslinking reaction, thereby covalently immobilizing the composite enzyme on the surface of functionalized carbon black, resulting in a composite enzyme-carbon black composite material. This covalent immobilization method effectively reduces the risk of enzyme migration, loss, and inactivation in high-solids-content anaerobic digestion systems, prolongs its effective action period, and gives the composite material the potential for recycling and reuse, effectively reducing enzyme consumption. The crosslinking agent described in this application is preferably prepared as a crosslinking agent solution with water before use and then added to the premixed solution for reaction. In some specific implementations, the mass concentration of the crosslinking agent solution is preferably 0.1 wt% to 5 wt%, more preferably 0.1 wt% to 1 wt%. In some specific implementations, after the crosslinking agent is added to the premixed solution, it is first stirred and then allowed to stand for reaction. The stirring time is preferably 10 min to 60 min, more preferably 20 min to 40 min. The standing time is preferably 10 min to 60 min, more preferably 20 min to 40 min.

[0040] This application also provides a method for dry anaerobic digestion using the above-mentioned composite enzyme-carbon black composite material, which includes adding the composite enzyme-carbon black composite material to organic solid waste for anaerobic fermentation.

[0041] The method described in this application does not require extensive dilution or complex pretreatment of high-solids raw materials, and is preferably applicable to the treatment of organic solid wastes such as residual sludge, kitchen waste, and mixtures of sludge and organic solid waste, especially suitable for the resource recovery process of organic solid wastes such as residual sludge with high solids content. The total solids content of the organic solid waste is preferably 10% to 30%, more preferably 15% to 25%.

[0042] Specifically, this application mixes immobilized composite enzyme-carbon black composite material with excess sludge at a predetermined ratio, and then performs a dry anaerobic digestion reaction after the materials are uniformly mixed. The mass ratio of excess sludge to carbon black in the composite material is preferably 100:1~5, more preferably 100:2~4. In some specific implementations, the mixing method is preferably mechanical stirring, the stirring time is preferably 20 min~60 min, more preferably 20 min~40 min, and the stirring speed is preferably 30 rpm~100 rpm, more preferably 40 rpm~60 rpm. In some specific implementations, the reaction temperature of the dry anaerobic digestion reaction is 30℃~40℃, preferably 35℃~40℃, more preferably 38±0.5℃; the initial pH value of the dry anaerobic digestion reaction is preferably 6~8, more preferably 6.5~7.5.

[0043] By introducing a stable and immobilized composite enzyme into a high-solids-content anaerobic system, the conversion of macromolecular organic matter such as proteins and cellulose in sludge into usable intermediates can be continuously promoted, improving the removal efficiency of volatile solids (VS) and total solids (TS), and providing a stable substrate source for subsequent methanogenesis. During the reaction, the composite enzyme-carbon black composite material can maintain the continuity of the hydrolysis phase over a relatively long operating cycle, helping to mitigate the adverse effects of substrate supply fluctuations under high-solids conditions on the reaction system, and enabling the dry anaerobic digestion process to maintain stable operation over a wide range of process conditions.

[0044] The present application is further illustrated below with reference to embodiments. The scope of protection of the present application is not limited to the following embodiments.

[0045] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels; Unless otherwise specified, room temperature or normal temperature in the embodiments of this application refers to 25±3℃.

[0046] The residual sludge used in this application was taken from the secondary sedimentation tank of an urban wastewater treatment plant. The total solids content (TS) was 16%, and the volatile solids (VS) accounted for 55% of the TS.

[0047] Example 1

[0048] Preparation of immobilized composite enzyme-carbon black composite material: 1. Preparation of oxygen-functionalized carbon black (1) Raw material processing: Take commercially available carbon black powder with a particle size of no more than 50 μm, disperse it in deionized water at a mass ratio of 1:20, and treat it with ultrasonic treatment at 300 W for 60 min to form a uniform suspension.

[0049] (2) Ozone oxidation treatment: The above suspension was transferred to a reaction vessel and oxidized by introducing ozone gas at 25°C. The ozone concentration was 60 mg / L and the gas flow rate was 1.0 L / min. The reaction was carried out continuously for 8 h. Mechanical stirring was maintained during the reaction, and the stirring speed was 200 rpm.

[0050] (3) Post-treatment: After the reaction is completed, the reaction solution is centrifuged at 8000 rpm for 10 min to separate the solid. The obtained solid is washed three times with deionized water and then vacuum dried at 60℃ for 24 h to obtain oxygen-containing functionalized carbon black, denoted as OC.

[0051] A series of characterizations were performed on the oxygen-containing functionalized carbon black. The characterization analysis showed that the prepared carbon black surface contains oxygen-containing functional groups such as carboxyl and hydroxyl groups.

[0052] 2. Ammonia treatment of carbon black surface

[0053] Take 1 g of the oxygen-containing functionalized carbon black prepared above, and ultrasonically disperse it in 50 mL of toluene at 300 W for 30 min. Then, add 5 mL of 3-aminopropyltriethoxysilane to the dispersion and stir the mixture at 80 °C for 8 h. After the reaction is complete, wash the resulting solid three times each with toluene and ethanol, and dry it under vacuum at 80 °C for 12 h to obtain ammoniated carbon black, denoted as OC-NH2.

[0054] 3. Preparation of immobilized composite enzyme-carbon black composite material

[0055] (1) Preparation of compound enzyme: Take neutral protease and cellulase, mix them in a mass ratio of 1:1 to prepare compound enzyme solution.

[0056] (2) Covalent immobilization reaction: 50 mL of acetic acid buffer solution (0.1 M, pH 4.8) and 80 mg of the above-mentioned complex enzyme solution were added to 1 g OC-NH2 and mixed thoroughly under stirring at 300 rpm for 0.5 h; then 0.25 mL of 0.5% glutaraldehyde solution was added to the system, and stirring was continued slowly for 30 min, followed by standing for 30 min. After the reaction was completed, the mixture was centrifuged at 3000 rpm / min for 15 min, the supernatant was discarded, and the mixture was washed with deionized water; then it was treated with 0.1 M ethanolamine solution for 15 min to block the unreacted aldehyde groups; after washing again and vacuum filtration, the immobilized complex enzyme-carbon black composite material was obtained.

[0057] Example 2

[0058] Applications of immobilized composite enzyme-carbon black composite materials: 1. Pretreatment and mixing of excess sludge The remaining sludge was mixed with the immobilized composite enzyme-carbon black composite material prepared in Example 1, wherein the mass ratio of the remaining sludge to the carbon black in the immobilized composite enzyme-carbon black composite material was 100:3. The mixture was stirred under mechanical stirring conditions (50 rpm) for 30 min to ensure that the materials were mixed evenly.

[0059] 2. Dry anaerobic digestion experiment

[0060] (1) Reaction conditions: The above-mixed materials are loaded into an anaerobic reactor with an effective volume of 1 L. The total solid content of the system is 16%, the reaction temperature is controlled at 38±0.5℃, and the initial pH is 6.5.

[0061] (2) Operation and monitoring: The reaction cycle is 20 days. During the reaction, gas samples are collected regularly to determine the methane production, and the pH, volatile fatty acids (VFAs), and ammonium nitrogen (NH4) of the system are monitored simultaneously. + -N) and soluble chemical oxygen demand (sCOD).

[0062] 3. Results of dry anaerobic digestion experiment

[0063] (1) Methane production: Under the above dry anaerobic conditions, the cumulative methane production of the system was 329.05 mL / g VS, which was higher than that of the control system without immobilized composite enzyme-carbon black composite material (Example 4).

[0064] (2) Organic matter removal effect: After the reaction, the removal rate of volatile solids (VS) was 73.5% and the removal rate of total solids (TS) was 45.2%.

[0065] (3) System operation: During the reaction, the peak concentration of volatile fatty acids was no higher than 550 mg / L, the concentration of ammonium nitrogen was maintained below 300 mg / L, no obvious inhibition was observed, and the system operated stably.

[0066] Example 3

[0067] Recycling and reuse of immobilized composite enzyme-carbon black composite materials: 1. Material recycling methods After the dry anaerobic digestion reaction is completed, the digested material is screened through a vibrating screen with a pore size of 2 mm to recover the immobilized composite enzyme-carbon black composite material, with a recovery rate of not less than 80%.

[0068] The recovered material was soaked in 0.1 M NaOH solution for 2 h to remove surface adhering substances, then washed with deionized water until neutral, and dried at 60°C for later use.

[0069] 2. Recycling Experiment

[0070] Three consecutive dry anaerobic digestion experiments were conducted using the same batch of recovered immobilized composite enzyme-carbon black composite material, with all other reaction conditions being the same as in Example 2.

[0071] Experimental results show that the methane production of the system during the three cycles was 352 mL / g VS, 340 mL / g VS and 328 mL / g VS, respectively, and the performance degradation rate was less than 7%.

[0072] The results show that the immobilized composite enzyme-carbon black composite material prepared in this application has good recycling and reuse performance, and can maintain a stable anaerobic digestion enhancement effect during multiple uses.

[0073] Example 4

[0074] 1. A dry anaerobic digestion experiment was conducted using the same method as in Example 2, except that the immobilized composite enzyme-carbon black composite material was not added during the pretreatment and mixing of the excess sludge in step 1. Only the excess sludge (taken from the secondary sedimentation tank of a municipal wastewater treatment plant, TS=16%, VS=55%) was loaded into the anaerobic reactor. The reaction temperature was controlled at 38±0.5℃, the initial pH=6.5, the total solids content (TS) at 16%, and the reaction period was 20 days. Other parameters included stirring, gas monitoring, and pH / VFAs / NH4. + The operations, such as -N / sCOD sampling and analysis, are completely consistent with those in Example 2.

[0075] 2. Results of dry anaerobic digestion experiment

[0076] (1) Methane production: The cumulative methane production was 226.55 mL / g VS, which was 45.2% lower than that in Example 2 (329.05 mL / g VS). The methane production rate slowed down significantly, and the peak methane production time was delayed by about 5 days. (2) Organic matter removal effect: The removal rate of volatile solids (VS) was 41.3% and the removal rate of total solids (TS) was 27.6%, both of which were much lower than the 73.5% and 45.2% of Example 2, indicating that the substrate degradation was incomplete; (3) System operation status: VFAs peak concentration reached 1920 mg / L, NH4 + The highest concentration of -N was 1380 mg / L, the pH fluctuation range of the system was ±0.8, and obvious acid inhibition and ammonia inhibition characteristics were observed. The operational stability was weaker than that of the experimental group with added immobilized composite material.

[0077] The results of the control group directly verified the core reinforcing effect of the immobilized composite enzyme-carbon black composite material: without the addition of the composite material, anaerobic digestion has typical bottlenecks such as low hydrolysis efficiency, slow methanogenesis rate, accumulation of inhibitors and poor system stability, which is in stark contrast to the high efficiency of Example 2, fully highlighting the superiority of the technical solution of the present invention.

[0078] Examples 5-7

[0079] The Influence of Carbon Black with Different Surface Oxygen Content on the Performance of Immobilized Composite Enzyme Materials

[0080] Immobilized composite enzyme-carbon black composite materials were prepared using the same method as in Example 1, except that the reaction time for ozone oxidation treatment in step 1 (2) was different. Oxygen-containing functionalized carbon blacks with different surface oxygen contents were prepared by adjusting the ozone oxidation treatment time, as shown in Table 1. Table 1. Effect of carbon black with different surface oxygen contents on the properties of immobilized composite enzyme materials

[0081] Dry anaerobic digestion experiments were conducted using the same method as in Example 2. Comparative results showed significant differences in methane yield during dry anaerobic digestion between the immobilized enzyme-carbon black composite materials prepared with carbon black of different surface oxygen contents. Specifically, the material prepared with carbon black of 18.8% surface oxygen content in Example 1 had the highest methane yield, at 329.05 mL / g VS; the materials prepared with carbon black of 11.3%, 22.1%, and 25.0% surface oxygen contents in Examples 5-7 had methane yields of 298.92 mL / g VS, 307.54 mL / g VS, and 275.57 mL / g VS, respectively.

[0082] Example 8

[0083] The effect of ammonia-free carbon black treatment on the enhanced effect of anaerobic digestion

[0084] The immobilized complex enzyme-carbon black composite material was prepared using the same method as in Example 1. The difference was that in Example 8, the carbon black surface amination treatment in step 2 was not performed. Instead, 1 g of unammoniated OC was directly used for the subsequent preparation of the immobilized complex enzyme-carbon black composite material.

[0085] Dry anaerobic digestion experiments were conducted using the same method as in Example 2. The results showed that there was a significant difference in methane yield between carbon black treated with and without ammoniation, as shown in Table 2. Table 2. Effects of ammoniation treatment on the properties of immobilized composite enzyme-carbon black composite materials

[0086] Table 2 shows that the total enzyme loading in the ammoniation group (Example 1) was 60 mg / g TS, and the methane yield was 329.05 mL / g VS; while the total enzyme loading in the non-ammoniation group (Example 8) was only 14 mg / g TS, and the methane yield was 245.62 mL / g VS. The results indicate that under the conditions of this example, ammoniation is a necessary prerequisite for the covalent grafting of enzyme and carbon black. Without the ammoniation step, the enzyme can only be physically adsorbed onto the carbon black surface, failing to achieve stable fixation, and is easily lost, directly leading to a significant decrease in methane yield.

[0087] Examples 9-11

[0088] Effect of compound enzyme ratio on the properties of immobilized compound enzyme-carbon black composite material

[0089] The immobilized complex enzyme-carbon black composite material was prepared using the same method as in Example 1, except that the mass ratio of protease to cellulase was different in step 3 (1) of the complex enzyme preparation. Details are shown in Table 3. Table 3. Effect of composite enzyme ratio on the properties of immobilized composite enzyme-carbon black composite material

[0090] Dry anaerobic digestion experiments were conducted using the same method as in Example 2. Comparative results showed that the system with a protease to cellulase mass ratio of 1:1 produced the highest methane yield, 329.05 mL / g VS. Systems with protease to cellulase mass ratios of 1:0.5, 1:2, and 2:1 produced methane yields of 249.82 mL / g VS, 305.73 mL / g VS, and 288.59 mL / g VS, respectively. These results indicate that when the protease to cellulase mass ratio is 1:1, the immobilized composite enzyme-carbon black composite material exhibits superior methanogenesis in dry anaerobic digestion.

[0091] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and inventive concept of this application, should be included within the scope of protection of this application.

Claims

1. A composite enzyme-carbon black material, characterized in that, Includes functionalized carbon black, composite enzymes, and cross-linking agents; The functionalized carbon black surface contains oxygen-containing functional groups and nitrogen-containing functional groups.

2. The composite enzyme-carbon black composite material according to claim 1, characterized in that, The complex enzyme includes one or more of protease, cellulase, lysozyme, and phospholipase.

3. The composite enzyme-carbon black composite material according to claim 2, characterized in that, The complex enzyme includes protease and cellulase; The mass ratio of the protease to the cellulase is 0.5 to 2:

1.

4. The composite enzyme-carbon black composite material according to any one of claims 1 to 3, characterized in that, The oxygen-containing functional groups include one or more of the following: carboxyl, hydroxyl, carbonyl, ether, sulfonic acid, and phosphate groups; The nitrogen-containing functional groups include one or more of primary amino, secondary amino, tertiary amino, quaternary ammonium, amide, and imino groups; The crosslinking agent includes one or more of glutaraldehyde, glyoxal, succinaldehyde, ethylene glycol diglycidyl ether, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride.

5. The composite enzyme-carbon black composite material according to claim 1, characterized in that, The mass ratio of the functionalized carbon black to the complex enzyme is 1:0.02~0.

10.

6. The method for preparing the composite enzyme-carbon black composite material according to any one of claims 1 to 5, characterized in that, Includes the following steps: Functionalized carbon black, composite enzyme, and crosslinking agent were reacted to obtain a composite enzyme-carbon black composite material.

7. The preparation method according to claim 6, characterized in that, The functionalized carbon black is prepared according to the following method: Carbon black is subjected to oxidation and ammoniation treatments in sequence to obtain functionalized carbon black.

8. The preparation method according to claim 7, characterized in that, The oxidizing agents used in the oxidation treatment include one or more of ozone, hydrogen peroxide, potassium permanganate, dilute nitric acid, sodium hypochlorite, and peracetic acid. The amination reagent used in the amination treatment includes one or more of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, ethylenediamine, and polyethyleneimine.

9. A method for dry anaerobic digestion using the composite enzyme-carbon black composite material according to any one of claims 1 to 5, characterized in that, This includes adding the composite enzyme-carbon black material to organic solid waste for anaerobic fermentation.

10. The preparation method according to claim 9, characterized in that, The total solids content of organic solid waste in the dry anaerobic digestion process is 10% to 30%.

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