Method for effectively promoting biofilm updating by utilizing elastic deformation of flexible carbon aerogel anode

Abstract

The invention belongs to the technical field of microbial fuel cells, and relates to a method for effectively promoting updating of a biological membrane by utilizing elastic deformation of a flexible carbon aerogel anode. The preparation method comprises the following steps: S1, preparing cellulose / lignin composite flexible carbon aerogel; s2, assembling a microbial fuel cell by using the cellulose / lignin composite flexible carbon aerogel as an anode, and carrying out electroactive biofilm electricity production efficiency analysis; and S3, taking out the cellulose / lignin composite flexible carbon aerogel biological anode after long-term operation from the microbial fuel cell, compressing, and researching the influence of the elastic deformation of the electrode on the long-term operation efficiency of the electroactive biological membrane. Compared with the prior art, the method provided by the invention has the advantages that the flexible carbon aerogel is used as the anode of the microbial fuel cell, and the actual problems of anode blockage, biological membrane aging and the like of the traditional microbial fuel cell can be solved through elastic compression, so that the rapid updating of the biological membrane and the long-term efficient output of the electrical property of the microbial fuel cell are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of microbial fuel cells, and relates to a method for effectively promoting biofilm renewal through elastic deformation of a flexible carbon aerogel anode. Background Art

[0002] Microbial fuel cells (MFCs) utilize electricity-generating microorganisms to decompose organic matter while transferring electrons outside the cells for pollutant degradation, energy production, or other ecological functions. Such bioelectrochemical systems are green, low-carbon, and environmentally friendly, and thus are of particular interest in today's "dual-carbon" context. Among all bioelectrochemical systems, electroactive biofilms are the core components, having a complex network structure, a unique interfacial environment, and a dynamic balance, and their state determines the capacity output and pollutant conversion efficiency of the entire bioelectrochemical system.

[0003] The efficient generation and transfer of extracellular electrons of electroactive biofilms are the key to the performance of bioelectrochemical systems. However, over time, dead cells gradually accumulate in the anode biofilm, affecting the diffusion of electron intermediates and nutrients. Such mass transfer limitations lead to nutrient limitations in the biofilm microenvironment and the accumulation of metabolic waste in the metabolically inert zone, accelerating the apoptosis of surrounding bacteria. The death of bacteria further exacerbates the mass transfer limitations, forming a vicious cycle. On the other hand, the thickening of the biofilm and the death of bacteria result in an increase in the remote electron transfer resistance and a decrease in the coulombic efficiency. In addition, the diffusion limitation caused by the increase in biofilm thickness leads to the accumulation of protons in the biofilm, exacerbating local acidification, which undoubtedly hinders the metabolic activity of the biofilm. The negative impact of the thick extracellular polymeric substances (EPS) secreted by bacteria cannot be underestimated either. Because the accumulation of non-conductive polysaccharides in EPS interferes with the electron transfer between redox-active proteins and the electrode, thus affecting the performance of electroactive biofilms. In traditional bioreactors, the methods for controlling biofilm aging mainly include controlling hydraulic conditions (stirring, aeration scouring), controlling ion concentrations, etc. These methods can alleviate the problems caused by excessive biofilm thickness to a certain extent, but electroactive biofilms cannot be aerated and scoured, and a certain ionic strength is required to ensure the conductivity of the solution. These methods are not applicable to electroactive biofilms. Researchers have found that biofilms formed by dead cells are looser and softer than those formed by live cells. Inspired by this, external stimulation of the electrode is considered to have the potential to promote the shedding and excretion of dead bacteria and extracellular polymeric substances, but there has been no report on solving the problem of biofilm aging through active operation of the electrode. Summary of the Invention

[0004] In view of the above problems, the present invention provides a method for effectively promoting biofilm renewal by using the elastic deformation of a flexible carbon aerogel anode. The cellulose / lignin composite flexible carbon aerogel is assembled as the anode into a microbial fuel cell. After the long-term operation of the microbial fuel cell, the bioanode is compressed to remove the aged biofilm. After re-cultivation, the output electrical performance of the microbial fuel cell is restored. The significant advantage of this method is that through the reasonable design of the anode, simple compression can promote biofilm renewal and improve the performance of the microbial fuel cell.

[0005] In the present invention, the cellulose includes any one of bacterial cellulose (BC), sodium carboxymethyl cellulose, and TEMPO-oxidized cellulose nanofibers (TOCNF). The lignin (AL) includes at least one of poplar alkali lignin, wheat straw alkali lignin, bamboo pulp alkali lignin, reed alkali lignin, cotton pulp alkali lignin, and bagasse alkali lignin.

[0006] The technical task of the present invention is achieved in the following manner: Using cellulose and lignin as raw materials, a regular and ordered tubular cellulose / lignin composite aerogel is prepared by the ice-templating method and freeze-drying method. Then, through carbonization and washing, a cellulose / lignin composite flexible carbon aerogel with regular shape is obtained. Subsequently, the prepared cellulose / lignin composite flexible carbon aerogel is assembled as the anode into a microbial fuel cell, and the electrical performance of the cell is tested. After continuing to operate for a long period (three to five months), a series of electrical performances of the cell are tested, and the clogging situation of the biofilm is observed. Then, the bioanode is compressed, and after running for two more cycles, a series of electrical performances of the microbial fuel cell are tested again, and the growth situation of the biofilm is observed.

[0007] The specific method includes:

[0008] S1. Prepare the cellulose / lignin composite flexible carbon aerogel;

[0009] S2. Use the cellulose / lignin composite flexible carbon aerogel as the anode to assemble a microbial fuel cell and conduct an analysis of the electricity generation efficiency of the electroactive biofilm;

[0010] S3. Take out the cellulose / lignin composite flexible carbon aerogel bioanode after long-term operation from the microbial fuel cell, compress it, and study the influence of the elastic deformation of the electrode on the long-term operation efficiency of the electroactive biofilm.

[0011] Preferably, the specific method for preparing the cellulose / lignin composite flexible carbon aerogel in step S1 is as follows: Dissolve lignin in an ammonia aqueous solution to prepare a solution with a solid content of 0.5 - 2.5 wt%. Additionally, prepare a cellulose suspension with a solid content of 0.5 - 2.5 wt%. Mix the two liquids in an equal volume ratio and pour them into a copper mold. Perform directional freezing with liquid nitrogen and use a freeze dryer for drying to obtain the cellulose / lignin composite aerogel. Subject the cellulose / lignin composite aerogel to high-temperature carbonization to obtain the cellulose / lignin composite flexible carbon aerogel.

[0012] The volume ratio of ammonia water to water in the ammonia aqueous solution used to dissolve lignin is (1 - 5):25.

[0013] The carbonization process is preferably carried out under an inert gas condition. The preferred carbonization heating process is as follows: Heat up at a rate of 2 - 10 °C / min (particularly preferably 3 - 6 °C / min) to 700 - 900 °C, hold for 1 - 4 h, and then cool to room temperature to obtain the cellulose / lignin composite flexible carbon aerogel.

[0014] Preferably, in step S2, use the cellulose / lignin composite flexible carbon aerogel as the anode to assemble a microbial fuel cell and conduct an analysis on the power generation efficiency of the electroactive biofilm. The specific method is as follows: Cut the flexible carbon aerogel into a cube with dimensions of 1.5 cm * 1 cm * 0.5 cm, and fix the carbon aerogel with a polytetrafluoroethylene platinum sheet electrode clip. Use the secondary sedimentation tank sludge as the inoculation source, domestic sewage as the substrate, and potassium ferricyanide as the cathode electron acceptor. Use a dual-chamber microbial fuel cell as the reactor to cultivate a mixed population of electroactive biofilms. Adopt an intermittent flow operation mode, connect an external resistance of 1000 Ω, and use a data acquisition device connected to a computer to test and record the external circuit voltage in real time. Evaluate the energy output of the electroactive biofilm through tests such as output voltage and power density.

[0015] The addition amount of the inoculation source is 5 - 20 mL, the addition amount of the substrate is 80 - 100 mL, the cathode uses carbon cloth or a carbon brush, and the concentration of potassium ferricyanide is 30 - 70 mM.

[0016] Preferably, in step S3, take out the cellulose / lignin composite flexible carbon aerogel bioanode after long-term operation from the microbial fuel cell, compress it, and study the influence of the elastic deformation of the electrode on the long-term operation efficiency of the electroactive biofilm. The specific operation is as follows: Take down the cellulose / lignin composite flexible carbon aerogel bioanode covered with biofilm after long-term operation from the electrode clip, place it on a bench vise with a scale, compress it, fix it again with the electrode clip and assemble it into the microbial fuel cell, compare the electrical performance of the microbial fuel cell before and after compression, and study the state of the electroactive biofilm through the adenosine triphosphate (ATP) metabolic activity test.

[0017] The strain of elastic compression is preferably 30% - 70%, and the number of compression times is preferably 5 - 20 times.

[0018] Compared with the prior art, the present invention provides a method for effectively promoting biofilm renewal by using the elastic deformation of a flexible carbon aerogel anode. It has the following outstanding beneficial effects:

[0019] The present invention uses green and environmentally friendly biomass raw materials, cellulose and lignin, to prepare a carbon aerogel with excellent compressibility. Due to the good conductivity, pore structure, and biocompatibility of this flexible carbon aerogel, it has a higher output voltage and power density as the anode of a microbial fuel cell. As the operation time extends, the anode will experience biofilm blockage and aging, accompanied by a decline in the performance of the microbial fuel cell. By simply compressing this flexible anode, the blocked and aged biofilm can be removed, improving the performance of the microbial fuel cell. This provides a general solution to the practical problem that the performance of microbial fuel cells is prone to decline over time. Description of the Drawings

[0020] Attached Figure 1 is the scanning electron microscope image of the cellulose / lignin composite flexible carbon aerogel obtained in Example 1;

[0021] Attached Figure 2 is the stress-strain curve of the cellulose / lignin composite flexible carbon aerogel obtained in Example 1 in the wet state;

[0022] Attached Figure 3 is the output voltage of the microbial fuel cell within 50 days of operation in Example 1;

[0023] Attached Figure 4 is the power density measured for the first time (operation for 30 days) of the microbial fuel cell in Example 1;

[0024] Attached Figure 5 is the schematic diagram of the elastic compression of the cellulose / lignin composite flexible carbon aerogel bioanode in Example 1;

[0025] Attached Figure 6 is the output voltage of the microbial fuel cell during long-term operation (180 days) in Example 1;

[0026] Attached Figure 7 is the comparison of the power density of the cellulose / lignin composite flexible carbon aerogel bioanode before and after elastic compression in Example 1;

[0027] Attached Figure 8 is the comparison of the metabolic activity of microorganisms before and after elastic compression of the cellulose / lignin composite flexible carbon aerogel bioanode in Example 1. Detailed Embodiments

[0028] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0029] The materials involved in all embodiments of the present invention can be obtained from commercial channels.

[0030] Example 1

[0031] 250 mg of poplar alkali lignin was dissolved in an ammonia solution (1 mL NH3·H2O and 24 mL deionized water), and 25 mL of TOCNF suspension (1.0 wt%, 250 mg TOCNF) was prepared. The above two liquids were mixed together and stirred for 0.5 h to ensure that the poplar alkali lignin and TOCNF were fully mixed. Then the mixed suspension was poured into a polytetrafluoroethylene mold with a copper sheet on the bottom. A rectangular copper box filled with liquid nitrogen was placed under the mold for directional freezing. After the directional freezing was completed, the cellulose / lignin composite aerogel was obtained after freeze drying for 48 h. The cellulose / lignin composite aerogel was heated to 800 ° C in an argon atmosphere at a heating rate of 3 ° C / min, and kept warm for 2 h to obtain a cellulose / lignin composite flexible carbon aerogel. For the morphology and compressibility of the cellulose / lignin composite flexible carbon aerogel, please refer to Figure 1 and Figure 2 .

[0032] The above-mentioned cellulose / lignin composite flexible carbon aerogel was used as the anode for the assembly of a microbial fuel cell. The dual-chamber microbial fuel cell consists of an anode chamber and a cathode chamber, which are separated by a cation exchange membrane. The carbon aerogel was cut into 1.5cm*1cm*0.5cm cubes as the anode of the battery and fixed with a polytetrafluoroethylene platinum electrode clamp, and a carbon brush was used as the cathode. The cathode liquid was a mixture of 100mL of potassium ferrocyanide (50mM) and potassium chloride (50mM). 10mL of active anaerobic sludge pre-acclimated bacteria was inoculated into the anode chamber of the assembled microbial fuel cell. And 90mL of artificial wastewater was fed as the anode liquid and cultured at 35℃. Artificial wastewater consists of CH3COONa (1g / L), NaH2PO4·2H2O (2.46g / L), Na2HPO4 (4.57g / L), NH4Cl (0.31g / L), KCl (0.13g / L), vitamin solution (5mL / L), and mineral solution (12.5mL / L). The load is an external resistor with a resistance of 1000Ω, and the output voltage is continuously detected using a data logger. When the voltage drops below 50mV, fresh artificial wastewater is re-injected. The output voltage within 50 days of operation is as follows Figure 3 In addition, the power density of the microbial fuel cell at peak voltage was measured when the operation time reached 30 days. Figure 4 .

[0033] Three months later, the electrical performance of the microbial fuel cell was tested again. Then, the bioanode was taken out of the anode chamber and placed on a benchtop flat clamp with a scale ruler and compressed 10 times at 50% stress. The compression diagram is shown in Figure 5 As shown. After each compression, the compressed liquid was collected with a rubber-tipped dropper, and then fresh phosphate buffer solution was added to the anode material. The compressed anode was reassembled into the battery, and the electrical performance of the MFC was tested after culturing for half a month. The output voltage and power density before and after compression were shown as follows: Figure 6 and Figure 7 As shown, the state of the electroactive biofilm was studied by ATP metabolic activity test, and the results are shown in 8. In summary, the electrochemical performance and biofilm state after compression were significantly better than before compression, proving the feasibility of using the elastic deformation of the flexible anode to renew the aged biofilm.

[0034] Example 2

[0035] 375 mg of alkali lignin was dissolved in an ammonia solution (1.5 mL NH3·H2O and 23.5 mL deionized water), and 25 mL of bacterial cellulose suspension (1.5 wt%, 375 mg bacterial cellulose) was prepared. The two liquids were mixed together and stirred for 0.5 h to ensure that the alkali lignin and bacterial cellulose were fully mixed. Then the mixed suspension was poured into a polytetrafluoroethylene mold with a copper sheet on the bottom. A rectangular copper box filled with liquid nitrogen was placed under the mold for directional freezing. After the directional freezing was completed, freeze-dried for 48 h to obtain a cellulose / lignin composite aerogel. The aerogel was heated to 700 ° C at a heating rate of 2 ° C / min in an argon atmosphere and kept warm for 3 h to obtain a cellulose / lignin composite flexible carbon aerogel.

[0036] The flexible carbon aerogel was used as the anode to assemble the microbial fuel cell. The dual-chamber microbial fuel cell consists of an anode chamber and a cathode chamber, which are separated by a cation exchange membrane. The carbon aerogel was cut into 1.5cm*1cm*0.5cm cubes as the anode of the battery and fixed with a polytetrafluoroethylene platinum electrode clamp, and the carbon brush was used as the cathode. The cathode liquid was a mixture of 100mL of potassium ferrocyanide (30mM) and potassium chloride (30mM). 5mL of active anaerobic sludge pre-acclimated bacteria were inoculated into the anode chamber of the assembled microbial fuel cell. And 95mL of artificial wastewater was fed as the anode liquid and cultured at 37℃. The artificial wastewater consisted of CH3COONa (1g / L), NaH2PO4·2H2O (2.46g / L), Na2HPO4 (4.57g / L), NH4Cl (0.31g / L), KCl (0.13g / L), vitamin solution (5mL / L), and mineral solution (12.5mL / L). The load was an external resistor with a resistance of 1000Ω, and the output voltage was continuously detected using a data logger. When the voltage dropped below 50mV, fresh artificial wastewater was re-injected. After a month of stable circulation, the power density of the microbial fuel cell at the peak voltage was measured.

[0037] Four months later, the electrical performance of the microbial fuel cell was tested again. The anode material was then removed from the anode chamber and placed on a benchtop flat clamp with a scale and compressed six times at 40% stress. After each compression, the compressed liquid was collected with a rubber-tipped dropper, and fresh phosphate buffer solution was added to the anode material. The compressed anode was reassembled into the cell, and the electrical performance of the MFC was tested after another half-month of culture, and the state of the electroactive biofilm was studied by ATP metabolic activity test.

[0038] Example 3

[0039] 500 mg of bamboo pulp alkali lignin was dissolved in an ammonia solution (3 mL NH3·H2O and 22 mL deionized water), and 25 mL of TOCNF suspension (2 wt%, 500 mg Tempo oxidized cellulose) was prepared. The two liquids were mixed together and stirred for 0.5 h to ensure that the bamboo pulp alkali lignin and TOCNF were fully mixed. Then the mixed suspension was poured into a polytetrafluoroethylene mold with a copper sheet on the bottom. A rectangular copper box filled with liquid nitrogen was placed under the mold for directional freezing. After the directional freezing was completed, the cellulose / lignin composite aerogel was obtained by freeze drying for 48 h. The cellulose / lignin composite aerogel was heated to 900 ° C at a heating rate of 5 ° C / min in an argon atmosphere and kept warm for 2 h to obtain a cellulose / lignin composite flexible carbon aerogel.

[0040] The above-mentioned cellulose / lignin composite flexible carbon aerogel was used as the anode for the assembly of the microbial fuel cell. The dual-chamber MFC consists of an anode chamber and a cathode chamber, separated by a cation exchange membrane. The carbon aerogel was cut into 1.5cm*1cm*0.5cm cubes as the anode of the battery and fixed with a polytetrafluoroethylene platinum electrode clamp, and the carbon cloth was used as the cathode. The cathode liquid was a mixture of 100mL of potassium ferrocyanide (60mM) and potassium chloride (60mM). And 15mL of active anaerobic sludge pre-acclimated bacteria were inoculated into the anode chamber of the assembled microbial fuel cell. And 85mL of artificial wastewater was fed as the anode liquid and cultured at 30℃. Artificial wastewater consists of CH3COONa (1g / L), NaH2PO4·2H2O (2.46g / L), Na2HPO4 (4.57g / L), NH4Cl (0.31g / L), KCl (0.13g / L), vitamin solution (5mL / L), and mineral solution (12.5mL / L). The external load is a resistor with a resistance of 800Ω, and the output voltage is continuously detected using a data logger. When the voltage drops below 40mV, fresh artificial wastewater is re-injected. After a month of stable circulation, the power density of the microbial fuel cell at peak voltage was measured.

[0041] After three and a half months, the electrical performance of the microbial fuel cell was tested again. Then, the anode material was removed from the anode chamber and placed on a benchtop small flat clamp and compressed 4 times at 70% stress. After each compression, the compressed liquid was collected with a rubber-tipped dropper, and then fresh phosphate buffer solution was added to the anode material. The compressed anode was reassembled into the cell, and the electrical performance of the MFC was tested after another half month of cultivation, and the state of the electroactive biofilm was studied by ATP metabolic activity test.

[0042] Example 4

[0043] 200 mg of reed alkali lignin was dissolved in an ammonia solution (1 mL NH3·H2O and 24 mL deionized water), and 25 mL of bacterial cellulose suspension (0.8 wt%, 200 mg bacterial cellulose) was prepared. The above two liquids were mixed together and stirred for 0.5 h to ensure that the reed alkali lignin and bacterial cellulose were fully mixed. Then the mixed suspension was poured into a polytetrafluoroethylene mold with a copper sheet on the bottom. A rectangular copper box filled with liquid nitrogen was placed under the mold for directional freezing. After the directional freezing was completed, the cellulose / lignin composite aerogel was obtained after freeze drying on a freeze dryer for 48 h. The aerogel was heated to 750 ° C at a heating rate of 10 ° C / min in an argon atmosphere and kept warm for 3 h to obtain a cellulose / lignin composite flexible carbon aerogel.

[0044] The above-mentioned cellulose / lignin composite flexible carbon aerogel was used as the anode for the assembly of microbial fuel cells. The dual-chamber MFC consists of an anode chamber and a cathode chamber, which are separated by a cation exchange membrane. The carbon aerogel was cut into 1.5cm*1cm*0.5cm cubes as the anode of the battery and fixed with a polytetrafluoroethylene platinum electrode clamp, and a carbon brush was used as the cathode. The cathode liquid was a mixture of 40mM potassium ferrocyanide and 40mM potassium chloride. 8mL of active anaerobic sludge pre-acclimated bacteria were inoculated into the anode chamber of the assembled microbial fuel cell. And 100mL of artificial wastewater was fed as the anode liquid and cultured at 33℃. The artificial wastewater consisted of CH3COONa (1g / L), NaH2PO4·2H2O (2.46g / L), Na2HPO4 (4.57g / L), NH4Cl (0.31g / L), KCl (0.13g / L), vitamin solution (50mL / L), and mineral solution (25mL / L). The load was an external resistor with a resistance of 1000Ω, and the output voltage was continuously detected using a data logger. When the voltage dropped below 50mV, fresh artificial wastewater was re-injected. After a month of stable circulation, the power density of the microbial fuel cell at the peak voltage was measured.

[0045] Five months later, the electrical performance of the microbial fuel cell was tested again. The anode material was then removed from the anode chamber and placed on a benchtop flat clamp and compressed 20 times at 60% stress. After each compression, the compressed liquid was collected with a rubber-tipped dropper, and fresh phosphate buffer solution was added to the anode material. The compressed anode was reassembled into the cell, and the electrical performance of the MFC was tested after another half-month of cultivation, and the state of the electroactive biofilm was studied by ATP metabolic activity test.

[0046] Example 5

[0047] 725 mg of cotton pulp alkali lignin was dissolved in an ammonia solution (1.5 mL NH3·H2O and 23.5 mL deionized water), and 25 mL of bacterial cellulose suspension (0.8 wt%, 725 mg bacterial cellulose) was prepared. The two liquids were mixed together and stirred for 0.5 h to ensure that the cotton pulp alkali lignin and bacterial cellulose were fully mixed. Then the mixed suspension was poured into a polytetrafluoroethylene mold with a copper sheet on the bottom. A rectangular copper box filled with liquid nitrogen was placed under the mold for directional freezing. After directional freezing, the cellulose / lignin composite aerogel was obtained after freeze drying on a freeze dryer for 48 h. The aerogel was heated to 850 ° C at a heating rate of 7 ° C / min in an argon atmosphere and kept warm for 3 h to obtain a cellulose / lignin composite flexible carbon aerogel.

[0048] The flexible carbon aerogel was used as the anode to assemble the microbial fuel cell. The dual-chamber MFC consisted of an anode chamber and a cathode chamber, separated by a cation exchange membrane. The carbon aerogel was cut into 1.5cm*1cm*0.5cm cubes as the anode of the battery and fixed with a polytetrafluoroethylene platinum electrode clamp, and a carbon brush was used as the cathode. The cathode liquid was a mixture of 70mM potassium ferrocyanide and 70mM potassium chloride. 9mL of active anaerobic sludge pre-acclimated bacteria were inoculated into the anode chamber of the assembled microbial fuel cell. 91mL of artificial wastewater was fed as the anode liquid and cultured at 34℃. The artificial wastewater consisted of CH3COONa (1g / L), NaH2PO4·2H2O (2.46g / L), Na2HPO4 (4.57g / L), NH4Cl (0.31g / L), KCl (0.13g / L), vitamin solution (2.5mL / L), and mineral solution (20mL / L). The load was an external resistor with a resistance of 1000Ω, and the output voltage was continuously detected using a data logger. When the voltage dropped below 50mV, fresh artificial wastewater was re-injected. After a month of stable circulation, the power density of the microbial fuel cell at the peak voltage was measured.

[0049] Four and a half months later, the electrical performance of the microbial fuel cell was tested again. The anode material was then removed from the anode chamber and placed on a benchtop flat clamp and compressed five times at 50% stress. After each compression, the compressed liquid was collected with a rubber-tipped dropper, and fresh phosphate buffer solution was added to the anode material. The compressed anode was reassembled into the cell, and the electrical performance of the MFC was tested after another half month of culture, and the state of the electroactive biofilm was studied by ATP metabolic activity test.

[0050] Example 6

[0051] 625 mg of bagasse alkali lignin and 2 mL of NH3·H2O were dissolved in an ammonia solution (composed of 2 mL of NH3·H2O and 23 mL of deionized water), and 25 mL of TOCNF suspension (2.5 wt%, 625 mg of TOCNF) was prepared. The two liquids were mixed together and stirred for 0.5 h to ensure that the bagasse alkali lignin and TOVNF were fully mixed. Then the mixed suspension was poured into a polytetrafluoroethylene mold with a copper sheet on the bottom. A rectangular copper box filled with liquid nitrogen was placed under the mold for directional freezing. After directional freezing, freeze-drying for 48 h obtained a cellulose / lignin composite aerogel. The aerogel was heated to 800 ° C at a heating rate of 4 ° C / min in an argon atmosphere and kept warm for 2 h to obtain a cellulose / lignin composite flexible carbon aerogel.

[0052] The above-mentioned cellulose / lignin composite flexible carbon aerogel was used as the anode to assemble a microbial fuel cell. The double-chamber MFC consists of an anode chamber and a cathode chamber, and is separated by a cation exchange membrane. The carbon aerogel was cut into a cube with dimensions of 1.5 cm * 1 cm * 0.5 cm as the anode of the battery and fixed with a PTFE platinum sheet electrode clip, and a carbon brush was used as the cathode. The catholyte was a mixed solution of 55 mM potassium ferricyanide and 55 mM potassium chloride. 5 mL of pre-acclimated active anaerobic sludge bacteria were inoculated into the anode chamber of the assembled microbial fuel cell. And 95 mL of artificial wastewater was fed as the anolyte and cultured at 35 °C. The artificial wastewater was composed of CH3COONa (1 g / L), NaH2PO4·2H2O (2.46 g / L), Na2HPO4 (4.57 g / L), NH4Cl (0.31 g / L), KCl (0.13 g / L), vitamin solution (2.5 mL / L), and mineral solution (20 mL / L). An external resistance of 1000 Ω was loaded, and the output voltage was continuously detected using a data collector. When the voltage dropped below 50 mV, fresh artificial wastewater was reinjected. After a stable cycle of one month, the power density of the microbial fuel cell at the peak voltage was measured.

[0053] Three and a half months later, the electrical performance of the microbial fuel cell was tested again. Then, the anode material was taken out of the anode chamber and placed on a bench vise, and compressed 7 times under a stress of 55%. After each compression, the compressed liquid was collected with a dropper, and then fresh phosphate buffer solution was replenished into the anode material. The compressed anode was reassembled into the battery, and the electrical performance of the MFC was tested after culturing for another half month, and the state of the electroactive biofilm was studied through ATP metabolic activity tests.

[0054] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for effectively promoting biofilm renewal by elastic deformation of a flexible carbon aerogel anode, characterized in that Including: S1. Prepare a cellulose / lignin composite flexible carbon aerogel; S2. Use the cellulose / lignin composite flexible carbon aerogel as the anode to assemble a microbial fuel cell, and conduct an analysis of the power generation efficiency of the electroactive biofilm; S3. Take out the cellulose / lignin composite flexible carbon aerogel bioanode after long-term operation from the microbial fuel cell, compress it, and study the influence of the elastic deformation of the electrode on the long-term operation efficiency of the electroactive biofilm.

2. The method for effectively promoting biofilm renewal by using the elastic deformation of a flexible carbon aerogel anode according to claim 1, wherein The specific method of using the cellulose / lignin composite flexible carbon aerogel as the anode to assemble a microbial fuel cell and conduct an analysis of the power generation efficiency of the electroactive biofilm in step S2 is as follows: Fix the flexible carbon aerogel with a polytetrafluoroethylene platinum sheet electrode clip, use the secondary sedimentation tank sludge as the inoculum source, domestic sewage as the substrate, and potassium ferricyanide as the cathode electron acceptor, use a two-chamber microbial fuel cell as the reactor to cultivate a mixed population of electroactive biofilms; adopt an intermittent flow operation mode, connect an external resistance of 1000 Ω, and use a data collector to connect to a computer to test and record the external circuit voltage in real time. Evaluate the energy output of the electroactive biofilm through tests such as output voltage, power density, polarization curve, and Coulomb efficiency.

3. A method for effectively promoting biofilm renewal by using the elastic deformation of a flexible carbon aerogel anode as described in claim 2, characterized in that This design and method can also be used for other flexible carbon aerogels, such as various types of flexible carbon aerogels based on graphene and carbon nanotubes.

4. The method for effectively promoting biofilm renewal by using the elastic deformation of a flexible carbon aerogel anode according to claim 1, wherein The specific method of taking out the cellulose / lignin composite flexible carbon aerogel bioanode after long-term operation from the microbial fuel cell, compressing it, and studying the influence of the elastic deformation of the electrode on the long-term operation efficiency of the electroactive biofilm in step S3 is as follows: Take down the cellulose / lignin composite flexible carbon aerogel bioanode covered with biofilm from the electrode clip, place it on a bench vise with a scale, compress the carbon aerogel, and after each compression, use a dropper to collect the compressed liquid, and then supplement the fresh PBS solution into the anode material. After the compression process is completed, fix the flexible anode with the electrode clip again, then assemble it into the microbial fuel cell, compare the electrical performance of the microbial fuel cell before and after compression, and study the state of the electroactive biofilm through ATP activity testing.

5. The method for effectively promoting biofilm renewal by using the elastic deformation of a flexible carbon aerogel anode according to claim 4, wherein The strain of elastic compression is 30% - 70%, and the number of compression times is 5 - 20 times.

6. A method for effectively promoting biofilm renewal by using the elastic deformation of a flexible carbon aerogel anode according to claim 4, characterized in that This method and operation process can also be used for other flexible carbon aerogels, such as various types of flexible carbon aerogels based on graphene and carbon nanotubes.

7. The method for effectively promoting biofilm renewal by using the elastic deformation of a flexible carbon aerogel anode according to claim, wherein After each compression, use a dropper to collect the compressed liquid, and then supplement the fresh PBS solution into the anode material.

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