Polyaniline magnetic biochar prepared based on biogas residues and application of polyaniline magnetic biochar in promoting enrichment of anaerobic co-digestion synergistic functional bacteria and methanogenic archaea in anaerobic co-digestion system

Abstract

The invention belongs to the technical field of kitchen waste recycling, and particularly relates to polyaniline magnetic biochar prepared on the basis of biogas residues and application of the polyaniline magnetic biochar in promoting enrichment of anaerobic co-digestion synergistic functional bacteria and methanogenic archaea in an anaerobic co-digestion system. According to the method, a proper amount of phosphate is added into the dry anaerobic digestion system of the kitchen garbage to activate the magnetic enteromorpha hydrothermal carbon so as to optimize the microbial community structure of the digestion system, enhance the microbial activity and enrich functional microorganisms such as clostridium and methane bag-shaped bacteria, so that the dry anaerobic digestion process of the kitchen garbage is effectively promoted, and the digestion efficiency of the kitchen garbage is improved. And the biogas yield is improved. And the method has great significance for realizing reduction, harmlessness and recycling of the kitchen garbage.

Description

Technical Field

[0001] The present invention belongs to the technical field of anaerobic digestion, and specifically relates to a polyaniline magnetic biochar prepared based on biogas residue and its application in promoting the enrichment of anaerobic co-digestion synergistic functional bacteria and methanogenic archaea in an anaerobic co-digestion system. Background Art

[0002] Anaerobic co-digestion of food waste and excess sludge (KWAS - CoAD) is an important way to realize the resource utilization of organic solid waste, but it generally has bottleneck problems such as low substrate mass transfer efficiency and unstable methane production performance. In the anaerobic co-digestion system, the presence and activity of specific populations of microorganisms are crucial to the success of the entire fermentation process. Anaerobic co-digestion is a complex multi-step biochemical process, including hydrolysis, acidification, acetogenesis and methanogenesis, and each stage depends on the participation of specific microorganisms. Among them, anaerobic co-digestion synergistic functional bacteria ( Massilibacterium ) play an important role in the decomposition of organic matter and electron transfer, and methanogenic archaea ( Methanosarcina ) are key microorganisms in the methanogenesis stage, and their abundance and activity directly affect methane production and system stability.

[0003] Current research has found that intermediate electron transfer mechanisms mediated by conductive materials offer new insights into enhancing anaerobic digestion. However, conventional biochar materials suffer from insufficient surface active sites and limited electron transfer efficiency, making them ineffective in promoting the enrichment and functional development of target microorganisms. Therefore, developing biochar that can efficiently enrich anaerobic co-digestion synergistic bacteria and methanogenic archaea is crucial for improving the efficiency of anaerobic co-digestion of food waste and excess sludge. Summary of the Invention

[0004] In order to address the deficiencies of the prior art, the purpose of the present invention is to provide a polyaniline magnetic biochar prepared based on biogas residue and its application in promoting the enrichment of anaerobic co-digestion synergistic functional bacteria and methanogenic archaea in anaerobic co-digestion systems.

[0005] To achieve the above object, the present invention adopts the following technical solutions: The first aspect of the present invention provides a polyaniline magnetic biochar prepared based on biogas residue, wherein the preparation of the polyaniline magnetic biochar comprises the following steps: S1, using ferrite solution to modify biochar to obtain magnetic biochar MDPC; S2. Measure magnetic biochar, add aniline solution and hydrochloric acid solution and stir; S3, adding ammonium persulfate and hydrochloric acid to the solution obtained in step S2, stirring in an ice bath after ultrasonic dispersion, and washing and drying the solid product to obtain the polyaniline magnetic biochar; Wherein, the biochar is produced by gradient pyrolysis of biogas residue.

[0006] In some embodiments of the present invention, step S1 specifically includes: producing biochar by gradient pyrolysis of biogas residue under a protective atmosphere, and modifying the biochar in a ferrite solution to obtain magnetic biochar MDPC.

[0007] In some embodiments of the present invention, step S1 specifically includes: under a protective atmosphere, gradient pyrolysis of biogas residue is performed, after pyrolysis is completed, washing, drying, and sieving through a 140-150 mesh sieve to obtain biochar, and the biochar is modified in a ferrite solution to obtain magnetic biochar MDPC.

[0008] In some embodiments of the present invention, after the biochar and the ferrite solution are mixed, 10 mol / L NaOH is added dropwise to adjust the pH to 9-11, and the mixture is stirred for 1 hour and then boiled for 1 hour to obtain magnetic biochar MDPC.

[0009] In the present invention, after the biochar is mixed with the ferrite solution, the pH value can be 9, 10 or 11, etc., but is not limited to the values ​​listed above. Other values ​​not listed within the above numerical range are also applicable.

[0010] In some embodiments of the present invention, the protective atmosphere is a nitrogen atmosphere or an argon atmosphere.

[0011] In some embodiments of the present invention, the gradient pyrolysis is carried out at a temperature of 550-600°C, a time of 2-3 h, and a heating rate of 3-5°C / min.

[0012] In the present invention, the gradient pyrolysis temperature can be 550°C, 560°C, 570°C, 580°C, 590°C or 600°C, etc., the gradient pyrolysis time can be 2h, 2.5h or 3h, etc., and the heating rate can be 3°C / min, 4°C / min or 5°C / min, etc., but are not limited to the values ​​listed above. Other values ​​not listed within the above numerical range are also applicable.

[0013] In some embodiments of the present invention, after pyrolysis is completed, the biochar having a particle size of less than 150 mesh is washed, dried, and sieved to collect the biochar before subsequent modification reactions are performed.

[0014] In some embodiments of the present invention, the washing is performed using ethanol and water.

[0015] In some embodiments of the present invention, the drying temperature is 100-105° C., and the drying time is 10-12 h.

[0016] In the present invention, the drying temperature can be 100°C, 101°C, 102°C, 103°C, 104°C or 105°C, and the drying time can be 10h, 11h or 12h, but are not limited to the values ​​listed above. Other values ​​not listed within the above range are also applicable. In some embodiments of the present invention, the drying is vacuum drying.

[0017] In some embodiments of the present invention, the ferrite solution is a mixed solution of FeCl3·6H2O and FeSO4·7H2O.

[0018] In some embodiments of the present invention, the FeCl3·6H2O and FeSO4·7H2O mixed solution contains Fe 3+ and Fe 2+ The molar ratio is 1.85:1.

[0019] In some embodiments of the present invention, in step S2, the mass volume ratio of the magnetic biochar, the aniline solution, and the hydrochloric acid solution is (1-10): (5-10): (90-110), g:mL:mL.

[0020] In some embodiments of the present invention, the mass volume ratio of the magnetic biochar, the aniline solution, and the hydrochloric acid solution is 5:8:100, g:mL:mL.

[0021] In some embodiments of the present invention, step S3 specifically includes: adding ammonium persulfate and hydrochloric acid to the solution obtained in step S2, stirring in an ice bath after ultrasonic dispersion, washing the solid product with deionized water and methanol until the washing liquid is neutral, and drying to obtain the polyaniline magnetic biochar.

[0022] In some embodiments of the present invention, step S3 specifically includes: adding ammonium persulfate and hydrochloric acid to the solution obtained in step S2, stirring at 780-800 r / min for 3-4 hours in an ice bath at 2-6°C after ultrasonic dispersion, washing the solid product with deionized water and methanol until the washing liquid is neutral, drying at 60-80°C for 20-25 hours, grinding after drying and passing through a 150 mesh sieve to obtain the polyaniline magnetic biochar.

[0023] wherein the ice bath temperature may be 2°C, 3°C, 4°C, 5°C or 6°C, etc., the stirring speed may be 780 r / min, 782 r / min, 784 r / min, 786 r / min, 788 r / min, 790 r / min, 792 r / min, 794 r / min, 796 r / min, 798 r / min or 800 r / min, etc., the stirring time may be 3.1 h, 3.2 h, 3.3 h, 3.4 h, 3.5 h, 3.6 h, 3.7 h, 3.8 h, 3.9 h or 4 h, etc., the drying temperature may be 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 78, 79°C or 80°C, etc., and the drying time may be 20 h, 21 h, 22 h, 23 h, 24 h or 25 h, etc., but are not limited to the values ​​listed above. Other values ​​not listed within the above numerical range are also applicable.

[0024] A second aspect of the present invention provides a method for promoting the enrichment of anaerobic co-digestion synergistic functional bacteria and methanogenic archaea in an anaerobic co-digestion system of food waste and excess sludge, comprising adding the above-mentioned polyaniline magnetic biochar to the anaerobic co-digestion system, wherein the concentration of the polyaniline magnetic biochar added to the anaerobic co-digestion system is 25 to 50 mg / g in terms of TS.

[0025] In some embodiments of the present invention, the volume ratio of food waste to seed sludge (TS) is 2-4:1.

[0026] In some embodiments of the present invention, the solid content in the anaerobic digestion system is 3% to 5%.

[0027] In some embodiments of the present invention, the pH of the digested substrate in the anaerobic digestion system is 6.0-8.0.

[0028] In some embodiments of the present invention, the reaction temperature in the anaerobic digestion system is 25°C to 35°C.

[0029] In some embodiments of the present invention, the reaction cycle in the anaerobic digestion system is 30 days.

[0030] The addition concentration of polyaniline magnetic biochar can be 25mg / g, 26mg / g, 27mg / g, 28mg / g, 29mg / g, 30mg / g, 31mg / g, 32mg / g, 33mg / g, 34mg / g, 35mg / g, 36mg / g, 37mg / g, 38mg / g, 39mg / g, 40mg / g, 41mg / g, 42mg / g, 43mg / g, 44mg / g, 45mg / g, 46mg / g, 47mg / g, 48mg / g g, 49 mg / g or 50 mg / g, etc., the volume ratio of food waste to inoculated sludge (TS) can be 2:1, 3:1 or 4:1, etc., the solid content in the anaerobic digestion system can be 3%, 4% or 5%, etc., the pH in the anaerobic digestion system can be 6, 7 or 8, etc., and the reaction temperature in the anaerobic digestion system can be 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C or 35°C, etc., but are not limited to the values ​​listed above, and other values ​​not listed within the above numerical range are equally applicable.

[0031] The third aspect of the present invention provides the use of the polyaniline magnetic biochar or the method in producing methane.

[0032] In some embodiments of the present invention, the application is to add 25 mg / g to 50 mg / g (in terms of TS) of polyaniline magnetic biochar to the anaerobic co-digestion system.

[0033] The beneficial effects of the present invention are: The present invention effectively promotes the anaerobic co-digestion of synergistic functional bacteria ( Massilibacterium ) and methanogenic archaea ( Methanosarcina) enrichment. The biochar prepared by the present invention using sludge resources has a high specific surface area, a porous structure and good electrical conductivity. The introduction of polyaniline significantly improves the electrical conductivity of the biochar and introduces rich amino / imine functional groups. The present invention adopts FeCl3·6H2O + FeSO4·7H2O modification to generate a ferromagnetic material mainly composed of Fe3O4, with a saturation magnetization intensity of up to 30-50 emu / g, which can be quickly separated under an external magnetic field. Fe3O4 nanoparticles are loaded on the surface of the biochar by electrostatic adsorption or chemical bonding to form a rough porous structure. The loading of ferroferric oxide nanoparticles enhances the magnetic response characteristics of the material. These characteristics enable the modified biochar to provide a suitable growth environment for the target microorganisms, promote interspecies electron transfer, and improve the metabolic activity and synergistic effect of the microorganisms, thereby optimizing the anaerobic co-digestion process and increasing methane production. The polyaniline magnetic biochar provided by the present invention can significantly improve the methane production performance of the anaerobic co-digestion system, which is of great significance for realizing the efficient energy conversion of organic solid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The SEM and XPS images of the polyaniline / ferroferric oxide dual-functional modified biogas residue-derived biochar (PANI@MDPC) prepared in the examples of the present invention are shown, where (a) is the SEM image of the unmodified biochar, (b) is the SEM image of PANI@MDPC; (c) is the XPS image of the unmodified biochar, and (d) is the XPS image of PANI@MDPC; Figure 2 FTIR images of unmodified biochar (DPC), magnetic biochar (MDPC) and polyaniline magnetic biochar (PANI@MDPC) prepared in the examples of the present invention; Figure 3 This is a graph showing the methane production of different treatment groups in an embodiment of the present invention; Figure 4 Graph showing the microbial diversity index of different treatment groups in the embodiment of the present invention; Figure 5 This is a graph showing the microbial richness at the bacterial phylum level for different treatment groups in the examples of the present invention; Figure 6 This is a microbial richness diagram at the bacterial genus level for different treatment groups in the examples of the present invention; Figure 7 This is a diagram of the microbial richness at the Archaea level in different treatment groups in the examples of the present invention. DETAILED DESCRIPTION

[0035] To further illustrate the present invention, the preparation and application effects of PANI@MDPC are described in detail so that those skilled in the art can more clearly understand the technical solution of the present invention. The technical solution of the present invention will be described in detail below with reference to specific embodiments and drawings.

[0036] Example 1 The preparation processes of unmodified biochar (DPC), magnetic biochar (MDPC), and polyaniline magnetic biochar (PANI@MDPC) are described below. 200 g of biogas residue from the anaerobic digestion of food waste at Qingdao Shifang Bioenergy Co., Ltd. was dehydrated in a hot air drying oven at 105°C for 24 h to a constant weight (moisture content <5%). After manual sorting to remove inert impurities such as gravel, the residue was ground to a powder using a planetary ball mill, passed through a 150-mesh sieve (0.106 mm), and stored in a sealed, dark-proof desiccator until ready for use.

[0037] Preparation of DPC by gradient pyrolysis: 20 g of pretreated biogas residue was placed in a quartz tube and placed in a programmable temperature-controlled tube furnace. High-purity nitrogen was introduced at a flow rate of 0.1 L / min for 20 minutes to expel all air. The tube furnace was then heated to 600°C at a rate of 5°C / min and maintained at this temperature for 2 hours, with nitrogen continuously introduced throughout to create an anaerobic environment. After the tube furnace cooled naturally to room temperature, the pyrolysis product was removed and washed alternately with ethanol and deionized water for 5–10 times. After filtration, the product was dried in a 105°C drying oven for 12 hours and ground through a 150-mesh sieve to produce DPC.

[0038] MDPC was prepared by coprecipitation: 5 g of DPC was accurately weighed using an electronic analytical balance and dissolved in 200 mL of deionized water. Stirring was performed at 800 r / min with a magnetic stirrer for 5 minutes until uniformly dispersed. Separately, 20.0 g of FeCl₃•6H₂O and 11.1 g of FeSO₄•7H₂O were weighed and dissolved in 600 mL of deionized water. The two solutions were mixed and stirred continuously at 800 r / min for 20 minutes. 10 mol / L NaOH solution was added dropwise to adjust the pH to 10. Stirring was continued for 1 hour using a magnetic stirrer. The mixture was heated to 100°C, boiled for 1 hour, and allowed to cool naturally to room temperature. Filtered using a Büchner funnel, the residue was washed alternately with deionized water and ethanol 5–10 times, dried in a drying oven at 70°C for 24 hours, and ground through a 150-mesh sieve to obtain MDPC.

[0039] PANI@MDPC was prepared by in-situ polymerization: 8 mL of aniline (purity ≥99.5%) and 2 g of MDPC were dissolved in 100 mL of 1 mol / L HCl solution and magnetically stirred for 5 minutes until uniformly dispersed. Separately, 2.5 g of ammonium persulfate (APS) was dissolved in 100 mL of 1 mol / L HCl solution and slowly added dropwise to the mixture (at a rate of <3 drops / second). The mixture was then ultrasonically dispersed for 1 hour. The sonicated solution was then placed in a magnetically stirred water bath at 5°C and 800 rpm for 4 hours to achieve in-situ polymerization. After sufficient reaction, the dark green solid product was washed alternately with deionized water and methanol for 5-10 times, dried in a vacuum oven at 70°C for 24 hours, ground, and passed through a 150-mesh sieve to obtain the carbon material PANI@MDPC of this example.

[0040] Figure 1 and Figure 2 The SEM, XPS and FTIR images of DPC, MDPC and PANI@MDPC are shown in the figure. Figure 1 (c) (d) and Figure 2 It can be seen that Fe 2+ / Fe 3+ The PANI@MDPC material prepared in this example has a specific surface area of ​​30.341 m 2 / g, micropore volume 2.596 m 2 / g, total pore volume 0.168 cm 3 / g, average pore diameter 24.014 nm.

[0041]

[0042] Example 2 The reactor setup consisted of five 500 mL borosilicate glass reactors (working volume 400 mL) equipped with a Teflon-sealed gas sampling valve and a 1.0 L aluminum-plastic air bag connected to a constant-temperature shaking incubator. The reactor operating parameters included the following: feed rate (25 mg / g–50 mg / g), temperature (25–35°C), pH (6.0–8.0), solids content (3%–5%), and TS (food waste: excess sludge ratio = 2–4:1).

[0043] After biochar was added to each reactor, the headspace was purged with 0.5 L / min high-purity nitrogen for 60 s to create an anaerobic environment (ORP < -300 mV). The reactors were sealed with butyl rubber stoppers and incubated in a thermostatic shaker (150 rpm) for 30 days. The CH4 / CO2 / H2 gas composition was monitored daily by gas chromatography (Agilent 7890B). Every 48 hours, 5 mL of the mixed solution was collected and centrifuged (8000 × g, 10 min) for analysis of VFAs, SCOD, and other parameters. When cumulative methane production showed no significant increase, a 50 mL digestion sample was collected from each reactor on day 30, frozen, and sent to Shanghai Meiji Biopharmaceutical Technology Co., Ltd. for metagenomic sequencing using the Illumina NovaSeq platform to analyze the microbial community structure and functional gene expression.

[0044] Example 3 The fixed reactor parameters were a dosage of 50 mg / g PANI@MDPC, a TS ratio of 2:1, an initial pH of 8.0, and a temperature of 35°C. Solids contents were set at 3%, 4%, and 5%. The reactor was operated as described in Example 2.

[0045] When the solid content is 3%, the cumulative methane production is 95.3 mL / g TS. Massilibacterium The abundance is 22.6%, Methanosarcina The abundance is 55.2%; the solid content is 4%, and the cumulative methane production is 108.7 mL / g TS. Massilibacterium The abundance is 24.9%, Methanosarcina The abundance is 57.5%; the solid content is 5%, and the cumulative methane production is 102.6 mL / g TS. Massilibacterium The abundance is 21.1%, Methanosarcina The abundance is 52.7%. The optimal solid content is determined to be 4%.

[0046] Example 4 The fixed reactor parameters were: a dosage of 50 mg / g PANI@MDPC, a solids content of 4%, a TS ratio of 2:1, a temperature of 35°C, and initial pH settings of 6.0, 7.0, and 8.0. The reactor was operated as described in Example 2.

[0047] When pH=6.0, the cumulative methane production is 98.9 mL / g TS. Massilibacterium The abundance is 20.8%, Methanosarcina The abundance is 53.3%; pH = 7.0, the cumulative methane production is 112.5 mL / g TS, Massilibacterium The abundance is 26.3%, Methanosarcina The abundance is 59.8%; pH = 8.0, the cumulative methane production is 100.7 mL / g TS, Massilibacterium The abundance is 23.7%, MethanosarcinaThe abundance was 54.9%, and the optimal pH was determined to be 7.0.

[0048] Example 5 The fixed parameters of the reactor were a dosage of 50 mg / g PANI@MDPC, a solid content of 4%, an initial pH of 7.0, and a TS ratio of 2:1. The temperatures were set at 25° C., 30° C., and 35° C. The reactor was operated as described in Example 2.

[0049] When the temperature is 25℃, the cumulative methane production is 92.4 mL / g TS. Massilibacterium The abundance is 19.5%, Methanosarcina Abundance is 51.1%; temperature is 30℃: cumulative methane production is 118.4 mL / g TS, Massilibacterium The abundance is 28.1%, Methanosarcina The abundance is 61.3%; the temperature is 35℃, and the cumulative methane production is 105.6 mL / g TS. Massilibacterium The abundance is 25.5%, Methanosarcina The abundance was 56.8%. The optimal temperature was determined to be 30°C.

[0050] Example 6 The fixed reactor parameters were a dosage of 50 mg / g PANI@MDPC, a solid content of 4%, an initial pH of 7.0, and a temperature of 30°C. The TS ratios were set at 2:1, 3:1, and 4:1. The reactor was operated as described in Example 2.

[0051] When TS=2:1, the cumulative methane production is 112.56 mL / g TS. Massilibacterium The abundance is 25.2%, Methanosarcina The abundance is 58.1%; TS=3:1, the cumulative methane production is 120.2 mL / g TS, Massilibacterium The abundance is 28.4%, Methanosarcina The abundance is 59.2%; TS=4:1, and the cumulative methane production is 123.56 mL / g TS. Massilibacterium The abundance is 30.8%, Methanosarcina The abundance was 64.0%, and the optimal TS ratio was determined to be 4:1.

[0052] Example 7 Based on Examples 3-6, the optimal parameters (4% solids content, pH = 7.0, temperature 30°C, TS = 4:1) were optimized and five treatments were set up: (a) control (CK, no biochar added), (b) 25 mg / g MDPC group, (c) 25 mg / g PANI@MDPC group, (d) 37.5 mg / g PANI@MDPC group, and (e) 50 mg / g PANI@MDPC group. The reactor was operated as described in Example 2.

[0053] The methane production curves of each reactor obtained in this example are as follows: Figure 3 and as shown in Table 2.

[0054]

[0055] As shown in Table 2, the 25 mg / g PANI@MDPC group increased the methane production to 150.63 mg / L TS, an increase of 15.9% compared with the control group, enhancing the methane production capacity of the system. Analysis of the microbial community in the reactor Figure 4 The alpha diversity of each bacterial group is shown. Figure 5 and Figure 6 Reflects the abundance of microorganisms at the phylum and genus levels, respectively. Figure 7 It is the change of bacterial species in the archaeal community.

[0056] From the perspective of Alpha diversity (such as Figure 4 As shown in the figure, the Chao index of the control group and the 25 mg / g PANI@MDPC group were 3605 and 3703, respectively; the Simpson index was 0.100584 and 0.147211, respectively; and the Shannon index was 3.945855 and 3.878272, respectively. These results show that although the addition of PANI@MDPC has a certain impact on the overall microbial diversity, it increases the relative abundance of the target functional bacteria. This may be because the unique structure of PANI@MDPC is a synergistic functional bacteria for anaerobic co-digestion ( Massilibacterium ) and methanogenic archaea ( Methanosarcina ) provides a suitable growth microenvironment, promotes their enrichment, and inhibits the growth of some irrelevant microorganisms.

[0057] Depend on Figure 5 (Changes in bacterial phylum level) It can be seen that Bacillus ( Bacillota ), Bacteroidetes ( Bacteroidetes ), Actinobacteria ( Actinobacteria ) and Proteobacteria ( Proteobacteria ) was the dominant phylum in each group. However, PANI@MDPC significantly altered the relative abundance of microorganisms at the phylum level. The relative abundance of Bacillus increased by 11.95% in the PANI@MDPC group, and the relative abundance of Proteobacteria increased by 114.5%. This indicates that the addition of PANI@MDPC further enhanced the position of dominant phyla associated with anaerobic digestion, which can be attributed to its high specific surface area and good electron transfer properties, which favor the metabolic activities of related bacterial communities.

[0058] At the bacterial genus level, the changes in microbial community structure significantly reflected the promoting effect of PANI@MDPC on the proliferation of specific microorganisms (e.g. Figure 6 In the 25 mg / g PANI@MDPC group, the genus Masilil ( Massilibacterium ) reached a relative abundance of 34.22%, significantly higher than the 27.48% of the control group. This is because PANI@MDPC has a unique conductive network that can promote interspecies electron transfer, making the genus Masilii ( Massilibacterium ) more efficiently participate in the hydrolysis of carbohydrates or proteins, generating short-chain fatty acids (SCFAs), alcohols, or hydrogen, providing substrates for subsequent hydrogen-producing, acetogenic, and methanogenic bacteria, thereby improving the overall performance of the system. This shows that the addition of PANI@MDPC further strengthens its dominant bacterial genera.

[0059] Archaea play a crucial role in anaerobic co-digestion methanogenesis. Figure 7 The effect of PANI@MDPC on the relative abundance of Archaea genus was shown. Compared with the control group, Methanosarcina ( Methanosarcina ) increased significantly in the group with PANI@MDPC. Specifically, Methanosarcina spp. ( Methanosarcina ) in the control group was 60.59%, while in the 25 mg / g PANI@MDPC group the relative abundance increased to 66.14%, becoming the dominant bacteria. In addition, Methanobrevibacterium ( Methanobrevibacter ), Methanothrix ( Methanothrix ), Methanogenum ( Methanocorpusculum ) in the control group were 2.52%, 0.48%, 0.78%, while in the 25 mg / g PANI@MDPC group they increased to 7.01%, 0.79%, 0.82%. Studies have shown that Methanosarcina ( Methanosarcina ) is a type of multitrophic methanogen with rich metabolic diversity. It can not only produce methane using H2 / CO2, but also produce methane by splitting acetic acid and using methanol, methylamine and other methyl-containing compounds as substrates, and plays a key role in the electron transfer process; Methanobacterium genus ( Methanobrevibacter ) and Methanosarcina ( Methanocorpusculum ) belong to hydrogenotrophic methanogens, producing methane through H2 / CO2; Methanothrix genus ( Methanothrix ) belongs to acetotrophic methanogens, producing methane through the acetate decomposition pathway. The significant increase in the relative abundance of the above archaeal genera in the PANI@MDPC group indicates that PANI@MDPC can effectively improve the diversity of archaea and selectively enrich the genus Methanosarcina ( Methanosarcina) and other functional microorganisms, the 25 mg / g PANI@MDPC group increased the methane production to 150.63 mg / L TS, an increase of 15.9% compared with the control group, enhancing the methane production capacity of the system.

[0060] In summary, the microbial community structure analysis clearly showed that PANI@MDPC selectively enriched the genus Emasilea ( Massilibacterium ), Methanosarcina ( Methanosarcina The discovery of a novel anaerobic co-digestion system with synergistic bacteria (e.g., sludge) and methanogenic archaea, which are primarily composed of anaerobic co-digestion bacteria, strengthens the functions of key bacterial communities, accelerates material transformation and electron transfer during the anaerobic co-digestion process, and significantly improves the system's methane production. This discovery has important theoretical and practical significance for achieving efficient anaerobic co-digestion of food waste and excess sludge.

[0061] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for parts thereof. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention. Although the above describes the specific implementation methods of the present invention, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A polyaniline magnetic biochar prepared based on biogas residue, characterized in that: The preparation of the polyaniline magnetic biochar comprises the following steps: S1, using ferrite solution to modify biochar to obtain magnetic biochar MDPC; S2. Measure magnetic biochar, add aniline solution and hydrochloric acid solution and stir; S3, adding ammonium persulfate and hydrochloric acid to the solution obtained in step S2, stirring in an ice bath after ultrasonic dispersion, and washing and drying the solid product to obtain the polyaniline magnetic biochar; Wherein, the biochar is produced by gradient pyrolysis of biogas residue.

2. The polyaniline magnetic biochar according to claim 1, characterized in that In step S1, the ferrite solution is a mixed solution of FeCl3·6H2O and FeSO4·7H2O.

3. The polyaniline magnetic biochar according to claim 2, characterized in that The FeCl3·6H2O and FeSO4·7H2O mixed solution 3+ and Fe 2+ The molar ratio is 1.85:

1.

4. The polyaniline magnetic biochar according to claim 1, wherein Step S1 specifically includes: under a protective atmosphere, performing gradient pyrolysis on the biogas residue, washing, drying, and screening after the pyrolysis is completed to obtain biochar, and modifying the biochar in a ferrite solution to obtain magnetic biochar MDPC.

5. The polyaniline magnetic biochar according to claim 1, wherein In step S2, the mass volume ratio of the magnetic biochar, the aniline solution, and the hydrochloric acid solution is (1-10):(5-10):(90-110), g:mL:mL.

6. The polyaniline magnetic biochar according to claim 1, characterized in that In step S2, the mass volume ratio of the magnetic biochar, the aniline solution, and the hydrochloric acid solution is 5:8:100, g:mL:mL.

7. The polyaniline magnetic biochar according to claim 1, characterized in that Step S3 specifically includes: adding ammonium persulfate and hydrochloric acid to the solution obtained in step S2, stirring in an ice bath after ultrasonic dispersion, washing the solid product with deionized water and methanol until the washing liquid is neutral, and drying to obtain the polyaniline magnetic biochar.

8. The polyaniline magnetic biochar according to claim 1, characterized in that Step S3 specifically includes: adding ammonium persulfate and hydrochloric acid to the solution obtained in step S2, stirring at 780-800 r / min for 3-4 hours in an ice bath pot at 2-6°C after ultrasonic dispersion, washing the solid product with deionized water and methanol until the washing liquid is neutral, drying at 60-80°C for 20-25 hours, grinding after drying and passing through a 150-mesh sieve to obtain the polyaniline magnetic biochar.

9. A method for promoting the enrichment of anaerobic co-digestion synergistic functional bacteria and methanogenic archaea in an anaerobic co-digestion system of food waste and excess sludge, characterized in that: The polyaniline magnetic biochar according to any one of claims 1 to 8 is added to the anaerobic co-digestion system, and the concentration of the polyaniline magnetic biochar in the anaerobic co-digestion system is 25 to 50 mg / g in terms of TS.

10. Use of the polyaniline magnetic biochar according to any one of claims 1 to 8 or the method according to claim 9 in producing methane.

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