Method for enhancing efficiency, reducing pollution and regulating flora by coupling magnetic biochar with dynamic membrane

Abstract

The invention discloses a magnetic biochar coupled dynamic membrane synergistic pollution reduction and flora regulation method, which comprises the following steps: adding magnetic biochar into an anaerobic dynamic membrane bioreactor for anaerobic digestion reaction, and adding 1.2-1.5 g of magnetic biochar into each liter of sludge mixed liquid in the anaerobic dynamic membrane bioreactor. The magnetic biochar is composed of a honeycomb-shaped carbon material obtained by pyrolyzing carbon through sodium citrate and Fe3O4 loaded on the surface of the honeycomb-shaped carbon material through a chemical coprecipitation method. According to the method, functional microorganisms such as methane filamentous bacteria and methane rod bacteria can be selectively enriched, the methane yield is increased by 30%-35%, membrane pollution is effectively relieved by improving the sludge floc structure, the service life of the membrane is prolonged, and technical support is provided for low-cost and low-energy-consumption operation of the anaerobic membrane bioreactor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of membrane bioreactor, in particular to a magnetic biochar coupled dynamic membrane synergistic pollution reduction and microbial community regulation method. BACKGROUND

[0002] An anaerobic membrane bioreactor (AnMBR) is a wastewater treatment system that combines membrane separation technology with anaerobic biological treatment and has been widely used in the field of pollution resourceization. The technology produces methane by degrading organic matter through anaerobic microorganisms, achieving wastewater purification and energy recovery. However, AnMBR still faces key bottlenecks such as high membrane material cost and membrane fouling (such as membrane scaling) in practical application. In addition, the anaerobic sludge in AnMBR has the characteristics of high viscosity and suspended solids in the mixed liquid, and fine sludge particles, biological polymers and inorganics will adhere and accumulate on the membrane surface, resulting in increased operating energy consumption and reduced treatment efficiency.

[0003] Dynamic membrane (DM) technology combines membrane separation technology with anaerobic bioreactors, providing a new path to solve these challenges, thus forming an anaerobic dynamic membrane bioreactor (AnDMBR). Compared with traditional anaerobic membrane reactors, the typical feature is to achieve solid-liquid separation through the filter cake layer (DM layer) naturally formed on the coarse pore support medium, and has the advantages of low membrane material cost, simple membrane module structure, high biomass retention efficiency, etc., thereby improving the degradation efficiency of organic pollutants.

[0004] Traditional AnDMBR completely relies on the in-situ formation of DM layer by sludge on the support mesh surface, and usually takes 15-30 days to form a stable filter cake layer. The effluent SS and COD are very high in the early stage, the reactor startup stage is slow, and once the hydraulic flushing is too strong or the sludge properties change, the DM layer is easily detached, resulting in a sharp deterioration of the effluent. SUMMARY

[0005] The purpose of the present application is to provide a magnetic biochar coupled dynamic membrane synergistic pollution reduction and microbial community regulation method, which introduces magnetic biochar as a conductive material into the anaerobic dynamic membrane bioreactor, effectively promotes the enrichment and functional exertion of target microorganisms, and realizes the regulation of microbial community while relieving membrane pollution. It provides technical support for low-cost and low-energy operation of anaerobic membrane bioreactor, and has important significance for improving anaerobic digestion efficiency.

[0006] In one aspect of the present application, a magnetic biochar is provided. According to embodiments of the present application, the magnetic biochar is composed of a honeycomb-like carbon material obtained by pyrolysis of sodium citrate and Fe3O4 loaded on the surface thereof by a chemical co-precipitation method.

[0007] In another aspect of the present application, the present application provides a method for preparing a magnetic biochar. According to an embodiment of the present application, the method comprises the following steps:

[0008] (1) honeycomb-like carbon material obtained by pyrolyzing sodium citrate;

[0009] (2) stirring and reacting the pyrolyzed carbon material with FeSO4·7H2O and anhydrous FeCl3 solution, while adding NaOH dropwise to obtain a precipitate, washing to neutral and drying to obtain the magnetic biochar.

[0010] In addition, the method for preparing a magnetic biochar according to the above embodiment of the present application can further have the following additional technical features:

[0011] In some embodiments of the present application, in step (1), the pyrolysis temperature is 550-650℃, the heating rate is 5-7℃ / min, and the pyrolysis time is 2-4h. Sodium citrate is selected as the precursor. On the one hand, the intramolecular polycarboxyl / hydroxyl structure is used to cause a severe dehydration-decarboxylation-spontaneous foaming reaction during pyrolysis. On the other hand, the sodium ion is used for in-situ chemical activation and reduction etching with metallic sodium, thereby constructing a honeycomb-like pore structure and a functional carbon material with high concentration of persistent free radicals. The superiority is more obvious compared with traditional biomass char.

[0012] In some embodiments of the present application, in step (2), the mass ratio of the materials FeSO4·7H2O and FeCl3 is (1:1.1)-(1:1.3), wherein the molar ratio of Fe²⁺ to Fe³⁺ is 1:2; the mass ratio of the pyrolyzed carbon material to the total amount of FeSO4·7H2O and FeCl3 is (1:15)-(1:20); the mass ratio of NaOH to the pyrolyzed carbon material is (50:1)-(100:1); the stirring reaction temperature is 65-70℃; the washing is performed using anhydrous ethanol and deionized water; the stirring reaction temperature is 65-70℃; and the washing is performed using anhydrous ethanol and deionized water.

[0013] By using a chemical co-precipitation method, Fe3O4 nanoparticles are generated in-situ on the surface of the honeycomb-like sodium citrate pyrolysis carbon at a molar ratio of Fe²⁺ to Fe³⁺ of 1:2 under alkaline conditions at 65-70℃. By means of the abundant oxygen-containing functional groups on the surface of the pyrolysis carbon, high dispersion loading and high magnetic responsiveness of the iron oxide are achieved through coordination, and finally a magnetic biochar with magnetic separation performance, high oxidation activity and honeycomb-like pore structure is obtained.

[0014] In another aspect of the present application, the present application provides a magnetic biochar coupled dynamic membrane synergistic pollution reduction and microbial community regulation method. According to an embodiment of the present application, the magnetic biochar is added to an anaerobic dynamic membrane bioreactor for anaerobic digestion reaction. The magnetic biochar is introduced into the anaerobic dynamic membrane bioreactor as a conductive material, and by regulating the operating parameters of the reactor (such as sludge concentration, temperature and stirring conditions), the enrichment of functional microorganisms and the electron transfer process are promoted, and at the same time, the filter cake layer of the dynamic membrane is used for solid-liquid separation, thereby improving the methane production rate and slowing down the membrane pollution.

[0015] In addition, the magnetic biochar coupled dynamic membrane synergistic pollution reduction and microbial community regulation method according to the above-mentioned embodiment of the present application can also have the following additional technical features:

[0016] In some embodiments of the present application, 1.2-1.5 g of magnetic biochar is added per liter of sludge mixed liquid in the anaerobic dynamic membrane bioreactor. The sludge concentration is 5-6 g / L, and the moisture content of the sludge is 84%-86%.

[0017] In another aspect of the present application, the present application provides an anaerobic dynamic membrane bioreactor system. According to an embodiment of the present application, for implementing the magnetic biochar coupled dynamic membrane synergistic pollution reduction and microbial community regulation method, it comprises:

[0018] a reactor body, which is internally provided with a dynamic plate membrane assembly;

[0019] a mixing and stirring system arranged at the bottom of the reactor body;

[0020] a temperature control system in communication with the reactor, for maintaining the internal temperature at 33-37℃;

[0021] and a water inlet and outlet system connected to the reactor body.

[0022] In addition, the anaerobic dynamic membrane bioreactor system according to the above-mentioned embodiment of the present application can also have the following additional technical features:

[0023] In some embodiments of the present application, the support material of the membrane assembly is a 300-400 mesh nylon net with a pore size of 65-70 μm and an effective filtration area of 0.015-0.020 m².

[0024] In some embodiments of the present application, a micro vacuum pump is further arranged between the headspace portion of the reactor and the bottom aeration chamber, and the average aeration flow rate is 3-5 L / min.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] 1) The magnetic biochar as a conductive medium enhances interspecies electron transfer between microorganisms, and its porous structure and selective enrichment capacity for functional microorganisms also synchronously optimize the sludge floc structure. On the one hand, the methanogenic efficiency is strengthened, that is, the conversion and consumption of intermediate metabolites such as organic acids are more rapid and efficient, the pH of the system is more stable, and the methane production rate is increased by 30%-35%; on the other hand, the membrane pollution can be effectively alleviated and the dynamic membrane formation can be regulated, that is, the effective formation time of the dynamic membrane is shortened, the growth rate of the transmembrane pressure difference (TMP) is significantly slowed down, and the membrane filtration cycle is effectively prolonged, thereby greatly reducing the frequency of physical and chemical cleaning. Overall, the economic efficiency and sustainability of the process are improved.

[0027] 2) The introduction of the magnetic biochar has a significant effect on the regulation of the bacterial flora, effectively promoting the enrichment of the anaerobic digestion functional bacteria and methanogenic archaea dominated by Chloroflexota, Methanosarcina and Methanobacterium, and optimizing the microbial community structure. The optimization of the microbial community structure not only improves the methanogenic performance of the system, but also makes the sludge in the reactor gradually transition from flocculent sludge to granular sludge with good settling performance. SMP (soluble microbial products) and EPS (extracellular polymeric substances) play a very important role in maintaining the mechanical strength of the sludge, so that the MLSS (mixed liquor suspended solids concentration) of the sludge does not rise too fast to cause the disintegration of the granular sludge. Meanwhile, the loaded Fe3O4 particles can also increase the floc density and improve the shear resistance, thereby alleviating the formation of dense filter cake layers.

[0028] 3) By adding the magnetic sodium citrate pyrolytic carbon composite material to the AnDMBR, the dynamic membrane layer can be quickly formed and maintained stable, the running flux is improved, and the entire system has strong impact load resistance, thereby overcoming the bottlenecks of the traditional AnDMBR such as slow start, low flux, heavy pollution and low removal efficiency of refractory substances. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The scanning electron microscope (SEM) and high-resolution X-ray photoelectron spectroscopy (XPS) of the BC / Fe3O4 prepared in Example 1 of the present application are shown in the figures, wherein (a) is the SEM of the biochar (BC), (b) is the SEM of the magnetic biochar (BC / Fe3O4), (c) is the high-resolution XPS spectrum of the O element of the magnetic biochar, and (d) is the high-resolution XPS spectrum of the Fe element of the magnetic biochar.

[0030] Figure 2 The Fourier transform infrared spectrogram of the BC / Fe3O4 prepared in Example 1 of the present application is shown in the figure.

[0031] Figure 3Structure diagram of anaerobic dynamic membrane bioreactor used in Example 2 of the present application;

[0032] Figure 4 Methane production rate change diagram of the control group and the experimental group in Example 3 of the present application;

[0033] Figure 5 Transmembrane pressure difference (TMP) change diagram of the control group and the experimental group in Example 3 of the present application;

[0034] Figure 6 Turbidity change diagram of the control group and the experimental group in Example 3 of the present application;

[0035] Figure 7 Microbial diversity analysis diagram of the control group and the experimental group in Example 3 of the present application, wherein (a) is a Venn diagram, and (b) is a principal coordinate analysis diagram (PCoA);

[0036] Figure 8 Microbial abundance diagram of the control group and the experimental group at the level of bacterial phylum in Example 3 of the present application;

[0037] Figure 9 Microbial abundance diagram of the control group and the experimental group at the level of archaeal genus in Example 3 of the present application. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0039] It should be noted that, in the embodiments of the present application, the pyrolysis temperature of sodium citrate is preferably between 550-650℃. If the temperature is lower than 550℃, the electrical conductivity and pore structure development of the biochar may not be sufficient; if the temperature is higher than 650℃, it may lead to a decrease in specific surface area and loss of functional groups. Within the preferred range, good electrical conductivity can be ensured to promote interspecies electron transfer, and rich pore structure can be maintained to promote microbial colonization.

[0040] Example 1

[0041] A method for preparing a magnetic biochar, comprising the following steps:

[0042] (1) After drying sodium citrate, pyrolyze it at a temperature increasing rate of 5℃ / min to 600℃ for 2h, and then decrease the temperature at a rate of 5℃ / min to obtain a carbon material with a honeycomb structure;

[0043] (2) 200 mg of carbon material was added to 400 mL of deionized water with 3.89 g of FeSO4·7H2O and 4.54 g of FeCl3 solution, the mixture was continuously stirred and mixed at 70°C, and 100 mL of 5 mol / L NaOH was added dropwise under continuous stirring to adjust the pH to 10. After filtration, the obtained material was washed with anhydrous ethanol and deionized water until the pH was 7, and finally dried in a vacuum drying oven at 110°C for 24 h to obtain dried magnetic biochar BC / Fe3O4.

[0044] Figure 1 and 2 are SEM, XPS and FTIR spectra of BC and BC / Fe3O4; Figure 2 The FTIR spectrum shows that the broad band at 3400 cm -1 -1 can be attributed to the O-H stretching vibration of adsorbed water molecules, and the peaks at 1381 cm -1 and 1576 cm -1 correspond to the bending absorption of carboxyl O-C-O function, i.e. bending vibration, which does not overlap with Fe-O bond. The FTIR spectrum clearly shows that iron oxide (peak at 574 cm -1 ) exists on the surface of pyrolytic carbon, and Fe3O4 is successfully loaded on biochar.

[0045] Example 2

[0046] As shown in Figure 3 , two anaerobic dynamic membrane bioreactors (AnDMBR) with exactly the same structure were constructed, one for the control group (without adding materials) and the other for the experimental group (adding magnetic biochar), respectively named Control-AnDMBR and BC / Fe3O4-AnDMBR. Specifically, an anaerobic dynamic membrane bioreactor system comprises:

[0047] The reactor body is internally provided with a dynamic plate membrane assembly; the membrane assembly used in the reactor is a self-made dynamic plate membrane assembly, the size of which is 0.11 m x 0.12 m, double-sided filtration, and the effective filtration area is 0.018 m 2 . The membrane support material is selected as a 300-mesh nylon net (the pore size is about 70 μm). The reactor is provided with an aeration chamber at the bottom, the aeration chamber is connected with an aeration device, a valve is arranged between the bottom and the top of the reactor, and a micro vacuum pump is arranged between the headspace of the reactor and the aeration chamber at the bottom, the average aeration flow of the micro vacuum pump is 3-5 L / min, which plays a role in biogas circulation on the one hand and makes the sludge mixed uniformly through the hydraulic shear force to control membrane pollution on the other hand.

[0048] A mixing and stirring system is installed at the bottom of the reactor. Specifically, the entire reactor is placed on a magnetic stirrer to ensure that the suspended sludge and added materials are mixed evenly within the system.

[0049] The temperature control system is connected to the reactor, and the reactor temperature is controlled by an insulated water tank, maintaining the temperature at 35±2℃.

[0050] The reactor is connected to an influent and effluent system. An DMBR is fed using an influent peristaltic pump, with the feedstock stored in a substrate tank. Drainage is achieved using an effluent peristaltic pump; a membrane pressure gauge is installed on the effluent pipe, with a pump-stop ratio set to 10 min:1 min, controlled by a time relay. A digital pressure sensor monitors the transmembrane pressure difference (TMP), and a gas bag is used to collect biogas. The reactor influent is artificially simulated wastewater, composed of sucrose, NH4Cl, KH2PO4, NaHCO3, and trace elements, with a carbon-nitrogen-phosphorus ratio of 200:5:1. The trace element components include NaCl, CaCl2·2H2O, ZnCl2, MgCl2·6H2O, AlCl3·6H2O, H3BO4, and (NH4)6Mo7O. 24 ·4H2O; FeCl2·4H2O, CoCl2·6H2O, MnCl2·4H2O, NiCl2·6H2O, CuCl2·2H2O, EDTA (12g / L); the specific concentration of each component is determined by the influent COD concentration.

[0051] Example 3

[0052] A method for achieving enhanced efficiency, reduced pollution, and microbial community regulation in a magnetic biochar coupled anaerobic dynamic membrane bioreactor, comprising the following specific steps:

[0053] Under laboratory conditions, two anaerobic dynamic membrane reactors with identical structures, as described in Example 2, were operated. During the reactor start-up phase, magnetic biochar prepared in Example 1 was added to the experimental group at a concentration of 1.2 g / L. The initial COD concentration of the influent substrate in both reactors was 2000 mg / L. Feeding and effluent were supplied via peristaltic pumps, and the hydraulic retention time was set to 42 h. During reactor operation, the influent load was gradually increased in six stages: 1-24 days: 1.1 g COD / L / d; 25-59 days: 1.7 g COD / L / d; 60-84 days: 2.3 g COD / L / d; 85-97 days: 2.8 g COD / L / d; 98-111 days: 3.4 g COD / L / d; 112-125 days: 4.0 g COD / L / d.

[0054] The water quality of the effluent of the two reactors was detected regularly, and the water quality indicators included pH, effluent COD concentration, effluent turbidity, protein concentration (PN), polysaccharide concentration (PS), but were not limited to the above indicators. The bubble size was adjusted during aeration by using a wet gas flow meter, and the change in transmembrane pressure difference (TMP) was monitored in real time by using a membrane pressure gauge. The biogas was collected by a gas bag at the top of the reactor, and the relative content of CO2 and CH4 in the biogas was detected by using gas chromatography. The entire reactor operation lasted for 125 days. During the experiment, the membrane support material was cleaned at the 43rd day, and after the reactor operation ended, the samples of the suspended sludge in the reactor and the dynamic membrane layer (DM layer) were collected, and the control group was named R1 and DM1, respectively, and the experimental group was named R2 and DM2, respectively. After freezing preservation, they were sent to Shanghai Meiji Biomedicine Technology Co., Ltd. to perform metagenomic sequencing by using DNBSEQ-T7 RSReagent Kit (FCL PE150) version 3.0 on a DNBSEQ-T7 sequencing platform, so as to analyze the structure of the microbial community and the expression of the functional genes.

[0055] As shown in Figure 4 , the change diagrams of the methane yield of the control group and the experimental group are shown. The average methane specific yield of the control group under each organic load was 96 mL CH4 / g COD, 162 mL CH4 / g COD, 203 mL CH4 / g COD, 259 mL CH4 / g COD, and 258 mL CH4 / g COD, respectively. After the addition of the material, the methane specific yield of the experimental group was 121 mL CH4 / g COD, 212 mL CH4 / g COD, 264 mL CH4 / g COD, 304 mL CH4 / g COD, and 296 mL CH4 / g COD. Obviously, with the addition of the material, the methane yield was significantly improved. When the influent load was low, the addition of the conductive material promoted the methane yield. When the organic load was increased, the methane production activity of the experimental group was significantly improved, and the methane yield was increased more obviously, which indicated that it promoted the interspecies electron transfer between the microorganisms and the methane production activity. In addition, the iron oxide precipitated on the surface of the biochar, so that the BC / Fe3O4 surface contained rich functional groups such as -C-O and -OH, thereby effectively improving the methane production and yield of the AnDMBR system, improving the microbial activity of the system, improving the stability of the system, and enhancing the tolerance of the system to high organic load.

[0056] TMP and turbidity are good indicators for measuring the pollution condition of the dynamic membrane layer, as Figure 5 and 6As shown, during the 125-day experimental period, the low organic load of the influent in the early stage led to unstable or non-existent dynamic membrane formation in both reactors. On day 43, the membrane support material was cleaned, and the influent COD concentration was increased. It was observed that turbidity showed a rapid downward trend in the short term (5-10 days) and remained stable for the following 80 days. Compared to the control group, the TMP rise rate in the experimental group was significantly slowed by 45%-55%, and the membrane lifespan was increased by 5-6 times. After day 120, the TMP only rose to around 30 kPa, while the control group showed a sharp upward trend on day 60. This mitigation of fouling is likely due to the conductive material promoting the formation of larger flocs through agglomeration, thus avoiding the formation of dense sediments. It also reduces the contribution of SMP and EPS to the sludge layer by adsorbing these substances. Furthermore, the experimental group with added materials was able to form a stable dynamic membrane in a shorter time, resulting in stable effluent turbidity over a long period, which also aligns with the slow increase in membrane pressure differential, mitigating membrane fouling.

[0057] Microbial community analysis of the reactor:

[0058] like Figure 7 As shown in the Venn and PCoA plots, there is a clear microbial aggregation between the control and experimental groups, and the differences within and between groups are significant, as indicated by the principal coordinate analysis. The reduction in suspended sludge and DM layer diversity reflects the selective richness of functional groups and promotes the degradation of VFAs and methane production.

[0059] Microbial abundance map at the phylum level (e.g.) Figure 8 As shown in the figure, Bacteroides and Chloroflexota are the dominant core bacteria at the phylum level in both suspended sludge and dynamic membrane layers. Their abundance varies slightly in the community composition of suspended sludge, but in the DM layer, Bacteroides are common pollutants, decreasing from approximately 25.23% in the control group to 20.34% in the experimental group with added conductive material. This reveals that magnetic biochar inhibits the growth of Bacteroides by adsorbing organic precursors, thereby mitigating or even reducing irreversible pollution. Chloroflexota contributes to the formation of a loose, permeable biofilm, increasing its abundance from 9.01-10.15% in DM1 to 18.67%-20.08% in DM2. This indicates that the addition of BC / Fe3O4 improves the floc structure, enhances shear resistance, and alleviates the formation of a dense filter cake layer.

[0060] Archaea play a crucial role in anaerobic digestion and methanogenesis, such as... Figure 9The microbial abundance changes at the archaea genus level of the control group and the experimental group are given. Methanothrix, as an acetate-trophic methanogen, is the main component in all samples, with hydrogen as nutrition and the ability to form biofilm, and its abundance in DM2 reaches about 30%, but in DM1, it is only 10.34%-15.68%, which is very likely to make the dynamic membrane layer in the experimental group more stable; Methanosarcina has a mixed metabolic pathway, can produce methane and SMP under fluctuation conditions, and can intensify gas pollution, that is, bubble formation blocks the channel, and its abundance in the control group is reduced from 23.4%-28.21% to 10.56%-13.40% in the experimental group, and at the same time, it is reduced by 5.32%-7.45% from DM1 to DM2, and the significant reduction of the abundance shows that BC / Fe3O4 has a relieving effect, and Methanosarcina is likely to limit its activity by adsorbing substrates such as acetic acid and hydrogen, thereby reducing gas pollution. In addition, Methanobacterium, as a hydrogen-trophic methanogen, promotes methane production through symbiotic relationship with bacteria, and its abundance in the experimental group increases, indicating that the material promotes the activity of acetogenic bacteria more effectively than hydrogen-producing methanogens.

[0061] In summary, the introduction of BC / Fe3O4, a conductive material, into the anaerobic dynamic membrane bioreactor can effectively improve the overall performance of the reactor, promote interspecies electron transfer between microorganisms, and increase the methane yield by 30%-35%. In addition, appropriate addition can also promote the formation of dynamic membrane layer and slow down membrane pollution, providing a clear idea for the control of membrane fouling. In addition, the microbial community structure analysis results show that BC / Fe3O4 has a significant effect on the regulation of bacterial flora, and selectively enriches Chloroflexota, Methanosarcina and Methanobacterium, which are mainly anaerobic digestion functional bacteria and methanogenic archaea. Not only does it improve the methane production performance of the system, but also improves the sludge floc structure, increases the shear resistance, and relieves the formation of dense filter cake layer.

[0062] The above is only an example and description of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, as long as they do not deviate from the structure of the present application or exceed the scope defined by the present claims, and should belong to the protection scope of the present application.

Claims

1. A magnetic biochar, characterized in that: The honeycomb carbon material obtained by pyrolysis of sodium citrate is composed of Fe3O4 loaded on its surface by chemical coprecipitation.

2. A method for preparing magnetic biochar according to claim 1, characterized in that, Includes the following steps: (1) Honeycomb carbon material obtained by pyrolysis of sodium citrate; (2) The pyrolyzed carbon material is stirred and reacted with FeSO4·7H2O and anhydrous FeCl3 solution, while NaOH is added dropwise to obtain a precipitate. After washing until neutral, the precipitate is dried to obtain the magnetic biochar.

3. The method for preparing magnetic biochar according to claim 2, characterized in that: In step (1), the pyrolysis temperature is 550-650℃, the heating rate is 5-7℃ / min, and the pyrolysis time is 2-4h.

4. The method for preparing magnetic biochar according to claim 2, characterized in that: In step (2), the mass ratio of FeSO4·7H2O to FeCl3 is (1:1.1)-(1:1.3), wherein the molar ratio of Fe²⁺ to Fe³⁺ is 1:2; the mass ratio of the pyrolyzed carbon material to the total amount of FeSO4·7H2O and FeCl3 is (1:15)-(1:20); the mass ratio of NaOH to the pyrolyzed carbon material is (50:1)-(100:1); the temperature of the stirring reaction is 65-70℃; and the washing is carried out using anhydrous ethanol and deionized water.

5. A method for enhancing efficiency, reducing pollution, and regulating microbial communities using magnetic biochar coupled with dynamic membranes, characterized in that: The magnetic biochar of claim 1 is added to an anaerobic dynamic membrane bioreactor to carry out an anaerobic digestion reaction.

6. The method for enhancing efficiency, reducing pollution, and regulating microbial communities using magnetic biochar coupled with dynamic membranes according to claim 5, characterized in that: Add 1.2-1.5g of magnetic biochar to each liter of sludge mixture in the anaerobic dynamic membrane bioreactor.

7. An anaerobic dynamic membrane bioreactor system, characterized in that, To implement the method of claim 5, comprising: The reactor body contains a dynamic plate membrane module. A mixing and stirring system is installed at the bottom of the reactor body; A temperature control system connected to the reactor is used to maintain the internal temperature at 33-37°C; And the inlet and outlet water systems connected to the reactor body.

8. The anaerobic dynamic membrane bioreactor system according to claim 1, characterized in that: The membrane module is supported by a 300-400 mesh nylon mesh with a pore size of 65-70 μm and an effective filtration area of ​​0.015-0.020 m².

9. The anaerobic dynamic membrane bioreactor system according to claim 1, characterized in that: It also includes a miniature vacuum pump located between the headspace of the reactor and the bottom aeration chamber, with an average aeration flow rate of 3-5 L / min.

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