Microbial fuel cell system and method with self-cleaning electrode coupled electric field lysis

Abstract

The application discloses a microbial fuel cell system and method of self-cleaning electrode coupling electric field lysis, aiming at solving the problems of excessive growth of anode biofilm, low utilization rate of sludge organic matter and unstable operation of a microbial fuel cell in sludge treatment. By applying intermittent reverse current at the anode and using CO2 gas generated at the cathode for purging, self-cleaning of the anode is realized, and accumulation of the biofilm is inhibited; meanwhile, the electric energy generated by the microbial fuel cell is used for electric field assisted lysis pretreatment, and the degradability of sludge organic matter is improved. The system comprises an acid-base adjusting tank, an electric field lysis tank, a microbial fuel cell reaction tank, an electric field lysis unit, an anode self-cleaning unit, a pulse feeding unit and a sludge recovery tank and the like. The method realizes the synergetic coupling of pretreatment and electricity generation and self-cleaning of the microbial fuel cell, improves the sludge degradation efficiency and electricity generation performance, realizes energy self-sufficiency, reduces energy consumption and operation cost, and has good industrial applicability and environmental benefits.

Description

Technical Field

[0001] This application relates to the field of wastewater and sludge treatment and resource utilization technology, specifically to a microbial fuel cell system and method with self-cleaning electrode coupled electric field to improve the performance and stability of sludge microbial fuel cells (MFC) and its treatment method. Background Technology

[0002] Sludge, an inevitable byproduct of wastewater treatment, presents a significant challenge for the field of environmental engineering in terms of its efficient and environmentally friendly treatment and resource utilization. Traditional sludge treatment processes, such as mechanical dewatering and drying, generally suffer from high energy consumption, low treatment efficiency, high sludge moisture content, and a tendency to cause secondary pollution, severely restricting the energy conservation, emission reduction, and sustainable development of wastewater treatment plants.

[0003] Microbial fuel cells (MFCs), as an emerging bioelectrochemical technology, can directly convert organic matter in sludge into electrical energy using the metabolic activities of microorganisms, while simultaneously achieving sludge reduction, stabilization, and resource recovery. However, MFCs still face several bottlenecks in practical applications, mainly including relatively low power generation efficiency, insufficient long-term operational stability, and high maintenance costs. Among these, excessive growth of biofilm on the anode or the formation of non-conductive biofilm (i.e., biofouling) is a key factor leading to MFC performance degradation. Excessively thick biofilms restrict substrate and electron transport, increasing internal resistance and significantly reducing the battery's power output and lifespan. Furthermore, the complex organic matter in sludge, especially extracellular polymeric substances (EPS) and insoluble organic matter, exhibits slow hydrolysis and biodegradation rates, limiting the effective utilization of substrate by electrogenic microorganisms and further affecting the power generation performance of MFCs.

[0004] In existing technologies, although some studies have attempted to improve the biodegradability of sludge through physical or chemical pretreatment methods, or to inhibit biofilm growth through electrochemical means, these methods are often independent and fail to form a synergistic integrated system. For example, acid-base adjustment can increase the soluble chemical oxygen demand (SCOD) of sludge, but cannot achieve complete decomposition; electrochemical methods may effectively remove biofilms, but if not properly controlled, they may damage the activity of electrogenic microorganisms. Therefore, how to develop an integrated sludge microbial fuel cell system that can effectively solve the problem of anode sludge coating, improve sludge substrate utilization efficiency, and achieve system energy self-sufficiency is a pressing technical challenge. Summary of the Invention

[0005] This application aims to address the technical problems of existing sludge microbial fuel cells (MFCs) in sludge treatment, such as performance degradation caused by excessive growth of the anode biofilm, low bioavailability of sludge organic matter, and poor long-term operational stability of the system.

[0006] To address the aforementioned technical problems, this application provides a sludge microbial fuel cell system with self-cleaning electrode coupled electric field cell dissolution, characterized in that the system comprises: a microbial fuel cell reaction tank and an anode self-cleaning unit; The microbial fuel cell reactor is divided into a microbial fuel cell anode reactor and a microbial fuel cell cathode reactor by a proton exchange membrane. The microbial fuel cell anode reactor is equipped with an anode, and the microbial fuel cell cathode reactor is equipped with a cathode. The anode surface is covered with microorganisms that have been pre-coated with a membrane. The anode self-cleaning unit includes a reverse current application device and a gas purging device for self-cleaning the anode. The reverse current application device is connected to the positive and negative electrodes of the anode in the anode reaction cell of the microbial fuel cell via discharge wires to apply a reverse voltage to the anode. The gas purging device includes a deoxygenation device and an internal circulation ventilation pipe connecting the deoxygenation device and the anode / cathode reaction cell of the microbial fuel cell. CO2 generated in the cathode reaction cell of the microbial fuel cell enters the anode reaction cell of the microbial fuel cell through the gas purging device to purge the biofilm covering the anode surface.

[0007] Furthermore, the anode surface of the microbial fuel cell anode reaction tank is provided with a bacterial inoculation port, and the anode surface of the microbial fuel cell anode reaction tank is provided with microorganisms that have undergone pre-film treatment. The microorganisms are electrogenic bacteria, and the pre-film treatment includes applying voltage to the electrogenic bacteria during the start-up phase.

[0008] Furthermore, the internal circulation ventilation pipeline includes an internal circulation intake pipeline and an internal circulation exhaust pipeline. The CO2 gas generated in the cathode reaction cell of the microbial fuel cell enters the deoxygenation device through the internal circulation intake pipeline, and the deoxygenated CO2 gas enters the anode reaction cell of the microbial fuel cell through the internal circulation exhaust pipeline to purge the biofilm covering the anode surface.

[0009] Furthermore, a pressure valve is installed on the internal circulation exhaust pipe, which controls the CO2 gas to enter the anode reaction tank of the microbial fuel cell at a preset purging gas speed.

[0010] Furthermore, the system also includes a feed pretreatment device, the outlet of which is connected to the microbial fuel cell reactor via a pump, for sending the pretreated wastewater into the microbial fuel cell reactor for wastewater degradation treatment; wherein, the feed pretreatment includes impurity filtration, acid-base adjustment and electric field cell lysis.

[0011] Furthermore, the feed pretreatment device includes a feed inlet, a filter screen, an acid-base adjustment tank, and an electric field lysis tank arranged from top to bottom; the filter screen is used to filter out solid impurities in the sludge; the acid-base adjustment tank is equipped with a stirrer, a motor for driving the stirrer, and a bottom plate of the adjustment tank; the outlet of the electric field lysis tank is connected to the anode reaction tank of the microbial fuel cell via a pump, which is used to adjust the pH value of the pumped sludge and pump the sludge that has been settling in the acid-base adjustment tank into the anode reaction tank of the microbial fuel cell.

[0012] Furthermore, the feed pretreatment device also includes an electric field-assisted cell lysis unit, which includes a cell lysis battery and a pair of parallel plate electrode heads, located below the electric field cell lysis tank. The cell lysis battery is used to perform pulsed electric field treatment on the sludge in the electric field cell lysis tank.

[0013] Furthermore, the system includes a sludge recovery tank, located at the bottom of the anode reaction tank of the microbial fuel cell, separated from the anode reaction tank by the bottom plate of the anode reaction tank, for collecting treated sludge.

[0014] Furthermore, a method for treating sludge microbial fuel cells using a self-cleaning electrode coupled with an electric field includes the following steps: S1: Initial feeding: Sludge is added through the feed inlet, and impurities in the sludge are filtered out through the filter screen. The sludge enters the waste tank through the waste outlet, and the filtered sludge enters the acid-base adjustment tank. S2: pH adjustment. Slowly add a 2 mol / L NaOH solution through the feed inlet and continuously stir with a stirrer until the pH of the sludge is precisely adjusted to 12. After adjustment, stop stirring and let the sludge stand at room temperature for 14 hours. After standing for 14 hours, add a 2 mol / L HCl solution through the feed inlet to adjust the pH of the sludge to 7.

[0015] S3: Inoculation of strains. After the acid-base adjustment is completed, all the sludge is pumped into the electric field cell lysis tank. The electrogenic bacteria are inoculated into the anode reaction tank of the microbial fuel cell through the inoculation port. Sodium acetate solution is added and stirred. After the reaction is complete, normal operation begins. Every two days, all the supernatant is taken out, and an equal amount of sodium acetate solution is added to replenish it and stirred thoroughly. S4: Electric field-assisted cell dissolution. After the sludge flows into the electric field cell dissolution tank, the cell dissolution battery releases electrical energy through the electrode head in the electric field cell dissolution tank to perform electric field-assisted cell dissolution pretreatment on the sludge. S5: Pulse feeding, the sludge in the electric field cell pool is pumped into the cavity of the anode reaction tank of the microbial fuel cell, and stirred evenly. The cathode reaction tank is filled with clean water. The anode reaction tank and the cathode reaction tank of the microbial fuel cell are separated by a proton exchange membrane. S6: Power generation and sludge degradation. During the operation of the anode reactor of the microbial fuel cell, the electrons generated by the reaction pass through the proton exchange membrane and form a current between the charging wires connecting the anode and the charging wires connecting the cathode. The electrical energy is stored in the reverse current application device. After the voltage across the external resistor of the anode reactor of the microbial fuel cell reaches the preset standard, wastewater degradation and power generation continue. S7: Anode self-cleaning. During the operation of the anode reaction tank of the microbial fuel cell, the microbial fuel cell battery applies a reverse voltage to the anode daily through the discharge wires connected to the positive electrode and the discharge wires connected to the negative electrode, causing the biofilm covering the anode surface to peel off. The gas pressure generated in the cathode reaction tank drives the CO2 produced by the reaction to enter the deoxygenation device through the internal circulation air intake pipe. The CO2 absorbs the residual O2 through the sodium dithionite solution in the deoxygenation device. Then, the pressure valve is opened to allow CO2 to be introduced into the anode through the internal circulation exhaust pipe to purge. The purging gas speed is controlled to cause the biofilm covering the anode surface to peel off. S8: Sludge discharge and recycling. In the anode reaction tank of the microbial fuel cell, when the voltage is lower than the minimum specified voltage, the bottom plate of the anode reaction tank is opened to allow the biodegraded sludge to enter the sludge recycling tank for resource utilization and to enter the next sludge treatment cycle.

[0016] Compared with the prior art, the present invention achieves the following technical effects: (1) The acid-base regulation and electric field-assisted cell lysis coupling pretreatment provided in this application significantly destroys the sludge cell structure, releases intracellular organic matter, and greatly improves the soluble chemical oxygen demand (SCOD) and bioavailability of sludge, providing more sufficient and more easily degradable substrates for microbial fuel cells (MFC), thereby enhancing the power generation performance and sludge degradation efficiency of microbial fuel cells.

[0017] (2) The two self-cleaning mechanisms provided in this application, intermittent reverse current and CO2 gas purging, effectively inhibit the excessive growth of anode biofilm and the formation of biofouling, maintain the electron transfer efficiency and activity of anode, significantly extend the stable operation cycle of microbial fuel cells, and reduce maintenance frequency and cost.

[0018] (3) The electrical energy generated by the microbial fuel cell prepared in this application is directly used to drive the electric field-assisted cell lysis pretreatment of sludge, realizing the energy cycle and self-sufficiency within the system, greatly reducing the dependence on external energy, reducing the total energy consumption and operating cost of sludge treatment, and having significant economic and environmental benefits.

[0019] (4) This application specifically selects and pre-attaches Geobacter, an electrogenic bacterium, and promotes the secretion of conductive EPS by applying a positive voltage, thereby enhancing the electron transfer efficiency and adhesion strength between the microorganism and the electrode. At the same time, CO2 purging helps maintain the pH stability of the anaerobic environment at the anode while providing physical cleaning, further optimizing the activity of the electrogenic bacteria.

[0020] (5) This application organically integrates multiple processes such as sludge pretreatment, microbial fuel cell power generation, anode self-cleaning, and pulse feeding to form a synergistic closed-loop system. Each unit promotes the other and jointly overcomes the limitations of single technologies in sludge treatment and energy recovery, achieving a significant improvement in overall performance.

[0021] (6) This application recovers electrical energy while efficiently degrading organic matter in sludge, and ultimately utilizes the treated sludge as a resource, which is in line with the current concept of circular economy and sustainable development and reduces the environmental pressure of sludge disposal. Attached Figure Description

[0022] For ease of explanation, the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0023] Figure 1 A schematic diagram of a sludge microbial fuel cell with a self-cleaning electrode coupled with an electric field to dissolve cells. Figure 2 Schematic diagram of each unit in a sludge microbial fuel cell system with self-cleaning electrode coupled electric field for cell lysis. Figure 3 This is a magnified view of a microbial fuel cell and a self-cleaning electrode. Figure 4 A flowchart of a sludge microbial fuel cell treatment method for self-cleaning electrode coupled electric field cell lysis. Reference numerals: 1. Feed inlet; 2. Filter screen; 3. Waste outlet; 4. Waste tank; 5. Acid-base adjustment tank; 6. Motor; 7. Agitator; 8. Adjustment tank handle; 9. First hinge; 10. Adjustment tank bottom plate; 11. Electric field lysing tank; 12. Strains inoculation port; 13. Microbial fuel cell anode reaction tank; 14. Lysing battery; 15. Electrode head; 16. Pump; 17. Microbial fuel cell cathode reaction tank; 18. Proton exchange membrane; 19. Anode; 20. Anode charging wire; 21. Cathode; 22. Cathode charging wire; 23. Reverse current application device; 24. Positive discharge wire; 25. Negative discharge wire; 26. Air inlet pipe; 27. Deoxygenation device; 28. Pressure valve; 29. ​​Exhaust pipe; 30. Anode reaction tank handle; 31. Second hinge; 32. Anode reaction tank bottom plate; 33. Sludge recovery tank. Detailed Implementation

[0024] The following are specific embodiments of the present invention, described in conjunction with the accompanying drawings, to further illustrate the technical solutions of the present invention. However, the present invention is not limited to these embodiments. Specific details, such as particular configurations, are provided in the following description merely to aid in a comprehensive understanding of the embodiments of the present invention. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention.

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0026] like Figure 1 , 2 As shown in Figure 3, a schematic diagram of each unit of a sludge microbial fuel cell system with a self-cleaning electrode coupled electric field is disclosed, and its internal structure is specifically disclosed. The sludge microbial fuel cell system provided in this application will be described in detail below through specific embodiments.

[0027] Example 1 See Figures 1-3 This is a schematic diagram of a sludge microbial fuel cell system with a self-cleaning electrode coupled to an electric field for cell lysis, as provided in this application. The sludge microbial fuel cell system specifically includes a feed pretreatment device, a microbial fuel cell reactor, and an anode self-cleaning unit. The outlet of the feed pretreatment device is connected to the microbial fuel cell reactor via a pump, used to send pretreated wastewater into the microbial fuel cell reactor for wastewater degradation treatment. The pretreatment includes impurity filtration, pH adjustment, and electric field cell lysis.

[0028] Specifically, such as Figure 1 As shown, the above-mentioned feed pretreatment device includes a feed inlet 1, a filter screen 2, an acid-base adjustment tank 5, and an electric field cell lysis tank 11 arranged from top to bottom.

[0029] The sludge to be treated enters the aforementioned feed pretreatment device through inlet 1. After entering, it passes through filter screen 2 to remove solid impurities such as stones and branches. The filtered sludge slurry enters the acid-base adjustment tank 5, while the impurities trapped by filter screen 2 are collected in the waste tank for further treatment.

[0030] The acid-base adjustment tank 5 is equipped with a pH sensor, a stirrer 7, a motor 6 for driving the stirrer 7, and a bottom plate 10. The stirrer 7 is vertically installed inside the cavity of the acid-base adjustment tank 5, with its lower shaft extending near the bottom of the tank without contacting the bottom plate 10. The motor 6 is fixed to the top of the acid-base adjustment tank 5 and drives the stirrer to rotate within the tank. In practical applications, the acid-base adjustment tank 5 collects sludge samples after preliminary filtration. While the stirrer 7 continues stirring, a 2 mol / L NaOH solution is slowly added through the inlet 1 until the pH of the sludge is precisely adjusted to 12. After adjustment, stirring is stopped, and the sludge is left to stand at room temperature (approximately 25°C) for 14 hours to promote alkaline hydrolysis and cell wall disruption. After the sludge has been allowed to stand, a 2 mol / L HCl solution is added through inlet 1 to precisely adjust the pH of the sludge to 7, thus completing the pretreatment of the sludge feed.

[0031] Furthermore, the bottom plate 10 of the aforementioned equalization tank is configured as a movable structure via the first hinge 9 and the equalization tank handle 8, covering the bottom opening of the acid-base equalization tank 5 body and corresponding to the feed inlet of the electric field lysis tank 11. The equalization tank handle 8 is located on the outside of the acid-base equalization tank 5 body and is connected to the movable leaf of the first hinge 9 for transmission, so as to drive the first hinge 9 to rotate the equalization tank bottom plate 10, thereby realizing the opening and closing of the bottom opening of the acid-base equalization tank 5 body. In practical applications, after the acid-base equalization of the sludge is completed in the acid-base equalization tank 5, the equalization tank handle 8 is used to drive the first hinge 9 to open the equalization tank bottom plate 10, allowing the acid-base equalized sludge to flow into the electric field lysis tank 11.

[0032] The main body of the electric field lysing cell 11 is made of corrosion-resistant PE material and has a volume of 500L.

[0033] like Figure 1 As shown, the outlet of the electric field lysing tank 11 is connected to the microbial fuel cell reactor via pump 16. The microbial fuel cell reactor is used to degrade sludge and generate electricity. In practical applications, pump 16 feeds the microbial fuel cell reactor from the electric field lysing tank 11 at 5-minute intervals and 10-minute intervals to avoid sludge accumulation in the reactor due to continuous feeding and to optimize substrate utilization efficiency.

[0034] Among them, such as Figure 1 As shown, the aforementioned microbial fuel cell reactor adopts a dual-chamber structure, including a microbial fuel cell anode reactor 13 and a microbial fuel cell cathode reactor 17. The microbial fuel cell anode reactor 13 contains an anode 19, and the microbial fuel cell cathode reactor 17 contains a cathode 21.

[0035] like Figure 3As shown, the anode reactor 13 and cathode reactor 17 of the microbial fuel cell are separated by a proton exchange membrane 18. During the operation of the anode reactor 13, electrons generated by the reaction pass through the proton exchange membrane 18, forming a current between the charging wire 20 connecting the anode 19 and the charging wire 22 connecting the cathode 21. Electrical energy is stored in the microbial fuel cell battery to monitor the voltage across the external resistor of the anode reactor 13. When the voltage reaches a maximum stable value of 400mV within 0.5 days and the current density is 500mA / cm², wastewater degradation and power generation continue. A sludge recovery tank 33 is also provided at the lower end of the microbial fuel cell reactor for collecting treated sludge. Figure 3 As shown, the microbial fuel cell anode reactor 13 is equipped with a movable anode reactor bottom plate 32, a second hinge 31 fixedly connected to the anode reactor bottom plate 32, and an anode reactor handle 30 pulsatorically connected to the second hinge 31. By operating the anode reactor handle 30, the second hinge 31 can be moved, thereby driving the anode reactor bottom plate 32 to open or close, allowing the treated sludge to flow into the sludge recovery tank 33.

[0036] Optionally, the anode 19 of the aforementioned microbial fuel cell is made of carbon cloth with a surface area of ​​100 cm², the cathode 21 is an activated carbon air cathode, and the anode reaction tank 13 of the microbial fuel cell has a volume of 100 L. The reaction tank is equipped with voltage and current sensors and an external resistor for real-time monitoring of power generation performance. The sludge recovery tank 33 can be made of PE material with a volume of 200 L, used to collect the sludge treated in the anode reaction tank 13 of the microbial fuel cell for subsequent resource utilization, such as as a soil conditioner or for further anaerobic digestion.

[0037] As an improvement, to enhance the electron transfer efficiency and adhesion strength between microorganisms and electrodes, this application pre-attaches microorganisms with a pre-film treatment on the surface of the anode 19. Specifically, the microorganisms are Geobacter, an electrogenic bacterium. The pre-film treatment includes applying a +0.3V voltage for 48 hours during the start-up phase to promote the secretion of more conductive extracellular polymeric substances (EPS) by the electrogenic bacteria, thereby enhancing the adhesion strength.

[0038] The pretreated neutral sludge is pumped from the aforementioned feed pretreatment device into the cavity of the anode reactor 13 of the aforementioned microbial fuel cell. Pre-cultured electrogenic *Geobacillus* bacteria are inoculated into the anode reactor 13 of the microbial fuel cell through the inoculation port 12. Simultaneously, a 2 g / L CH3COONa solution is pumped in through the feed port 1, and the reaction is stirred for 9 hours to complete the reactor startup. After startup, the reactor operates normally for one week. Every two days, all supernatant is pumped out and an equal amount of 2 g / L CH3COONa solution is added to replenish it, followed by stirring for 30 minutes to achieve continuous wastewater degradation and electricity generation.

[0039] Furthermore, in some embodiments, after the microbial fuel cell anode reactor 13 is operating normally and generating electricity, this application also proposes to use the electrical energy generated by the microbial fuel cell to perform electric field-assisted cell lysis pretreatment on the sludge entering the microbial fuel cell reactor. By destroying the sludge cells, the biodegradability of the sludge organic matter is improved.

[0040] Specifically, such as Figure 1 As shown, the aforementioned feed pretreatment device also includes an electric field-assisted cell lysis unit, located between the electric field cell lysis tank 11 and the anode reaction tank 13 of the microbial fuel cell. This unit includes a cell lysis battery 14 and a pair of parallel plate electrode heads 15, with an electrode spacing of 5 mm. The sludge in the electric field cell lysis tank 11 is subjected to pulsed electric field treatment by the electric field-assisted cell lysis unit, further destroying the sludge cells.

[0041] In some embodiments, the lysing battery 11 can be connected to the reverse current application device 23 via a cable. When the power generated by the microbial fuel cell reaches a set threshold, the system automatically starts the electric field-assisted lysing unit, connecting the electrical energy generated by the microbial fuel cell to the electric field-assisted lysing unit via a cable for pulsed electric field treatment of the sludge in the electric field lysing tank 11.

[0042] As another improvement, this application proposes to address the anode sludge coating problem by adding an anode self-cleaning unit to the aforementioned sludge microbial fuel cell system. Specifically, this unit includes a reverse current application device and a gas purging device. By applying an intermittent reverse current to the anode of the microbial fuel cell and using CO2 gas generated at the cathode to purge the anode surface, the anode achieves its self-cleaning function, effectively inhibiting excessive biofilm accumulation and maintaining electrode activity.

[0043] Specifically, such as Figures 1-2As shown in the illustration, this embodiment of the application uses a microbial fuel cell battery as the reverse current application device 23. The reverse current application device 23 is connected to the positive and negative electrodes of the anode 19 in the anode reaction tank 13 of the microbial fuel cell via a positive discharge wire 24 and a negative discharge wire 25, respectively. The reverse current application device 23 is used to apply a reverse voltage of -0.2V to the anode 19 for 10 minutes daily to disrupt the hydrogen bonds and hydrophobic interactions of the extracellular polymeric substances (EPS) within the biofilm, preventing sludge from forming a film on the anode surface while preserving the activity of electrogenic bacteria.

[0044] The aforementioned gas purging device specifically includes a deoxygenation device 27 and an internal circulation ventilation pipe connecting the deoxygenation device 27 and the anode / cathode reaction tank of the microbial fuel cell. The internal circulation ventilation pipe includes an internal circulation inlet pipe 26 and an internal circulation outlet pipe 29. The diameter of the internal circulation ventilation pipe is 5 mm, used to drive CO2 flow using the gas pressure (0.1-0.3 bar) generated at the cathode reaction tank 17 of the microbial fuel cell. CO2 gas generated in the cathode reaction tank 17 enters the deoxygenation device 27 through the internal circulation inlet pipe 26. The deoxygenation device 27 contains sodium dithionite solution to allow CO2 to absorb residual O2 before purging. The deoxygenated CO2 gas enters the anode reaction tank 13 of the microbial fuel cell through the internal circulation outlet pipe 29, purging the surface of the anode 19 to be covered with a biofilm. A pressure valve 28 is installed on the internal circulation exhaust pipe 29. The pressure valve 28 controls the CO2 gas to enter the anode reaction tank 13 of the microbial fuel cell. The pressure valve 28 controls the CO2 gas purging speed to be ≤0.1L / min, each purging lasts for 10 seconds, and the interval between each purging is 4 hours.

[0045] Example 2: like Figure 4 As shown, this application also provides a method for treating sludge microbial fuel cells using a self-cleaning electrode coupled with an electric field to dissolve cells. The specific operation steps are as follows: S1. Preliminary feeding and filtration: The organic sludge to be treated is conveyed to the preliminary feeding unit through the feed inlet 1. The sludge is first filtered through a stainless steel filter screen 2 (5mm aperture) to remove large impurities such as stones and branches. The filtered sludge slurry enters the acid-base adjustment tank 5, while the impurities trapped by the filter screen 2 are collected in the waste tank 4.

[0046] S2. Acid-base adjustment: In acid-base adjustment tank 5, a sample of sludge after preliminary filtration is collected. By controlling the feed rate, the solids content of the sludge is controlled at 3%-5% (too high a solids content results in high viscosity, while too low a content leads to poor mass transfer). While the agitator 7 is stirring thoroughly, a 2 mol / L NaOH solution is slowly added through inlet 1 until the pH of the sludge is precisely adjusted to 12. After adjustment, stirring is stopped, and the sludge is left to stand at room temperature (approximately 25°C) for 14 hours to promote alkaline hydrolysis and cell wall disruption. After standing, a 2 mol / L HCl solution is slowly added through inlet 1 until the pH of the sludge is precisely adjusted to 7.

[0047] S3. Inoculation and Start-up of the Microbial Fuel Cell Anode Reactor: The acid-base conditioned sludge from the acid-base conditioning tank 5 is fed into the electric field lysing tank 11 via the conditioning tank handle 8. Pre-cultured Geobacter, an electrogenic bacterium, is inoculated into the microbial fuel cell anode reactor 13 through the inoculation port 12 on the anode surface 19. Simultaneously, a 2 g / L sodium acetate solution is introduced through the feed port 1 pump 16. The reaction is carried out for 9 hours, completing the start-up of the microbial fuel cell anode reactor. After the microbial fuel cell anode reactor is in operation for one week, all supernatant is removed every two days via pump 16, and an equal amount of 2 g / L sodium acetate solution is added to replenish it, ensuring continuous wastewater degradation and electricity generation. During the start-up phase, a +0.3V voltage is applied to the anode for 48 hours to promote the secretion of more conductive EPS (such as riboflavin) by the electrogenic bacteria, enhancing their adhesion strength on the anode surface.

[0048] S4. Electric field-assisted lysis: Before new sludge enters the anode reaction tank 13 of the microbial fuel cell from the electric field lysis tank 11, the lysis battery releases electrical energy through the electrode head in the electric field lysis tank to perform electric field-assisted lysis pretreatment on this part of the sludge, further improving the biodegradability of the sludge organic matter.

[0049] S5. Pulse feeding: The sludge in the electric field cell lysis tank 11, which has been adjusted to neutral pH, is introduced into the cavity of the normally operating microbial fuel cell anode reaction tank 13 through pump 16. The feeding mode adopts a strategy of feeding for 5 minutes and then stopping for 10 minutes to avoid sludge accumulation in the anode area due to continuous feeding, and to optimize substrate transport and utilization. After each feeding, the mixture is stirred for 30 minutes to achieve uniformity.

[0050] S6. Anode Self-Cleaning: During the long-term operation of the anode reactor 13 of the microbial fuel cell, anode self-cleaning is performed daily; Reverse Current Cleaning: A reverse voltage of -0.2V is applied to the anode for 10 minutes daily. The reverse current aims to disrupt the hydrogen bonds and hydrophobic interactions of the extracellular polymeric substances (EPS) within the biofilm, thereby loosening and removing part of the biofilm, preventing excessive sludge coating on the anode surface. Simultaneously, the voltage and time are precisely controlled to preserve the activity of electrogenic bacteria; CO2 Gas Purging: An internal circulation pipe (straight) is installed between cathodes 21 and 19. In a cathode reaction cell (5 mm in diameter), the gas pressure (approximately 0.1-0.3 bar) generated by the cathode reaction cell 17 drives the flow of CO2. Before purging, the CO2 passes through a sodium dithionite solution in the deoxygenation device 27 to absorb any residual O2, ensuring that the purging gas does not introduce oxygen. The purging gas velocity is controlled at ≤0.1 L / min to avoid disturbing the anaerobic bacteria at the anode. Each purging lasts for 10 seconds and is performed every 4 hours. This physical purging, in conjunction with the reverse current, removes the sludge accumulated on the electrode surface while ensuring a low anaerobic bacteria loss rate.

[0051] S7. Power Generation and Sludge Degradation: After adding neutral sludge, the voltage across the external resistor of the anode reactor 13 of the microbial fuel cell is continuously monitored. Within 0.5 days, the system detects a voltage with a maximum stable value of 400mV. For sludge that has been acid-base regulated, the current density can reach 500mA / cm². Under this stable voltage and current density, the system continuously degrades wastewater and generates electricity. The electrical energy generated by the anode reactor 13 of the microbial fuel cell is stored in the reverse current application device 23 and is directly used to apply reverse current to the anode 19 in the anode reactor 13 of the microbial fuel cell, realizing energy circulation and self-sufficiency within the system.

[0052] S8. Sludge Discharge and Recycling: When the voltage of the anode reaction tank 13 of the microbial fuel cell is lower than 50mV, it indicates that most of the organic matter in the sludge has been degraded and the power generation efficiency has decreased significantly. At this time, the anode reaction tank handle 30 drives the second hinge 31 to open the bottom plate 32 of the anode reaction tank, so that the biodegraded sludge enters the sludge recycling tank 33 for further resource utilization and enters the next sludge treatment cycle.

[0053] Compared with the prior art, the optimization of the anode self-cleaning mechanism in this application and its impact on the activity of electrogenic bacteria are as follows: 1. Anode Pre-film Formation and Start-up Optimization: Before starting the anode reactor 13 of the microbial fuel cell, the anode (carbon cloth) is pre-film formed in activated sludge containing enriched Geobacter. During the start-up phase, a constant voltage of +0.3V (relative to the Ag / AgCl reference electrode) is applied to the anode by an external power source for 48 hours. The constant voltage of +0.3V helps to screen and enrich electrogenic bacteria and stimulates them to secrete more conductive extracellular polymers, thereby enhancing the electron transfer efficiency between the microorganisms and the electrode and the adhesion strength of the biofilm, laying the foundation for subsequent stable power generation.

[0054] 2. Precise control of intermittent reverse current: During normal system operation, at 2:00 AM daily (when the power generation load is relatively low), a reverse voltage of -0.2V (relative to the Ag / AgCl reference electrode) is applied to the anode via a programmable DC power supply for 10 minutes. The purpose of this reverse voltage is to selectively disrupt the hydrogen bonds and hydrophobic interactions of non-electrogenic microorganisms on the outer layer of the biofilm or extracellular polymers (EPS) in excessively thick biofilms, causing them to loosen or detach, thereby preventing the formation of a dense, non-conductive film on the anode surface. By precisely controlling the voltage amplitude and duration, it is ensured that while removing dirt, the activity of the core electrogenic bacteria and the conductive EPS structure are not significantly damaged. The system evaluates the cleaning effect by monitoring changes in anode impedance and current density, and fine-tunes the reverse current parameters as necessary.

[0055] 3. Anaerobic Protection of Cathode CO2 Circulation Purging: During the anode self-cleaning process, CO2 gas generated by the cathode is used for purging. A 5mm diameter internal circulation pipe is installed between the cathode and anode. The gas production pressure (0.1-0.3 bar) of the cathode reaction tank 17 is sufficient to drive the CO2 gas through this pipe. To ensure a strictly anaerobic environment in the anode chamber, a deoxygenation device 27 containing freshly prepared sodium dithionite solution is connected in series on the CO2 entry pipe into the anode chamber. Sodium dithionite, as a strong reducing agent, can efficiently absorb trace amounts of O2 that may be entrained in the CO2. The purging gas velocity is strictly controlled at ≤0.1L / min to avoid causing excessive shear stress or disturbance to the anode anaerobic bacterial community. Each purging lasts for 10 seconds and is performed every 4 hours to ensure that the anode surface remains clean while minimizing the loss of electrogenic bacteria.

[0056] 4. Performance Monitoring and Feedback: The system continuously monitors the voltage, current density, anode impedance, and COD removal rate of the microbial fuel cell. When the anode impedance increases significantly or the current density decreases continuously, it indicates that the anode biofilm may have overgrowth or fouling problems. At this time, the control system will automatically trigger or adjust the reverse current and CO2 purging parameters according to the preset logic to restore anode performance. This closed-loop feedback control mechanism ensures the intelligence and efficiency of anode self-cleaning, thereby ensuring the long-term stable operation and high power generation performance of the MFC.

[0057] Those skilled in the art to which this application pertains may make various modifications or additions to the specific embodiments described, or adopt similar methods to replace them, without departing from the inventive concept of this application or exceeding the scope defined by the appended claims.

Claims

1. A sludge microbial fuel cell system with self-cleaning electrode coupled electric field lysis, characterized in that, The system includes: a microbial fuel cell reactor and an anode self-cleaning unit; The microbial fuel cell reactor is divided into a microbial fuel cell anode reactor (13) and a microbial fuel cell cathode reactor (17) by a proton exchange membrane (18). The microbial fuel cell anode reactor (13) is provided with an anode (19), and the microbial fuel cell cathode reactor (17) is provided with a cathode (21). The surface of the anode (19) is provided with microorganisms that have been pre-coated with a membrane. The anode self-cleaning unit includes a reverse current application device (23) and a gas purging device for self-cleaning the anode. The reverse current application device (23) is connected to the positive and negative electrodes of the anode (19) in the microbial fuel cell anode reaction pool (13) through a positive discharge wire (24) and a negative discharge wire (25) respectively, for applying a reverse voltage to the anode (19). The gas purging device includes a deoxygenation device (27) and an internal circulation ventilation pipe connecting the deoxygenation device (27) and the microbial fuel cell anode / cathode reaction pool. The CO2 generated in the microbial fuel cell cathode reaction pool (17) enters the microbial fuel cell anode reaction pool (13) through the gas purging device for purging the biofilm covering the anode surface. The anode surface of the microbial fuel cell anode reaction tank (13) is provided with a strain inoculation port (12), and the anode surface of the microbial fuel cell anode reaction tank (13) is provided with microorganisms that have undergone pre-film treatment. The microorganisms are Geobacter, and the pre-film treatment includes applying a voltage to Geobacter during the start-up phase. The applied voltage is +0.3V for 48 hours to enhance the adhesion strength. The internal circulation ventilation pipe includes an internal circulation intake pipe (26) and an internal circulation exhaust pipe (29). The CO2 gas generated in the cathode reaction tank (17) of the microbial fuel cell enters the deoxygenation device (27) through the internal circulation intake pipe (26). The deoxygenated CO2 gas enters the anode reaction tank (13) of the microbial fuel cell through the internal circulation exhaust pipe (29) to purge the biofilm covering the anode (19) surface. The internal circulation exhaust pipe (29) is equipped with a pressure valve (28), which controls CO2 gas to enter the anode reaction tank (13) of the microbial fuel cell according to a preset purging gas speed. The pressure valve (28) controls the CO2 gas purging gas speed to be ≤0.1L / min, each purging lasts for 10 seconds, and the interval between each purging is 4 hours.

2. The sludge microbial fuel cell system with self-cleaning electrode coupled electric field lysis according to claim 1, characterized in that, It also includes a feed pretreatment device, the outlet of which is connected to the microbial fuel cell reactor via a pump (16) for sending the pretreated wastewater into the microbial fuel cell reactor for wastewater degradation treatment; wherein, the feed pretreatment includes impurity filtration, acid-base adjustment and electric field cell lysis.

3. The sludge microbial fuel cell system with self-cleaning electrode coupled electric field lysis according to claim 2, characterized in that, The feed pretreatment device includes a feed inlet (1), a filter screen (2), an acid-base adjustment tank (5), and an electric field cell lysis tank (11) arranged from top to bottom. The filter screen (2) is used to filter out solid impurities in the sludge. The acid-base adjustment tank (5) is equipped with a stirrer (7), a motor (6) for driving the stirrer, and a bottom plate (10). The outlet of the electric field cell lysis tank (11) is connected to the anode reaction tank (13) of the microbial fuel cell through a pump (16) to adjust the pH value of the pumped sludge and to pump the sludge that has been settling in the electric field cell lysis tank (11) into the anode reaction tank (13) of the microbial fuel cell.

4. The sludge microbial fuel cell system with self-cleaning electrode coupled electric field lysis according to claim 3, characterized in that, The feed pretreatment device also includes an electric field-assisted cell dissolution unit, which includes a cell dissolution battery (14) and a pair of parallel plate electrode heads (15), located below the electric field cell dissolution pool (11), to perform pulse electric field treatment on the sludge in the electric field cell dissolution pool (11).

5. The sludge microbial fuel cell system with self-cleaning electrode coupled electric field lysis according to claim 1, characterized in that, The system includes a sludge recovery tank (33), which is located at the bottom of the anode reaction tank (13) of the microbial fuel cell and is separated from the anode reaction tank (13) by the bottom plate (32) of the anode reaction tank, for collecting the treated sludge.

6. A method for treating sludge microbial fuel cells using a self-cleaning electrode coupled with an electric field to dissolve cells, based on any one of claims 1-5, characterized in that, Includes the following steps: S1: Initial feeding: Sludge is added through the feed inlet (1), and impurities in the sludge are filtered out through the filter screen (2). The sludge enters the waste tank (4) through the waste outlet (3), and the filtered sludge enters the acid-base adjustment tank (5). S2: pH adjustment. Slowly add a 2 mol / L NaOH solution through the feed inlet (1) and stir continuously with a stirrer until the pH of the sludge is precisely adjusted to 12. After the adjustment is completed, stop stirring and let the sludge stand at room temperature for 14 hours. After standing for 14 hours, add a 2 mol / L HCl solution through the feed inlet (1) to adjust the pH of the sludge to 7. S3: Inoculation with strains, after pH adjustment, all sludge is pumped into the electric field cell lysis tank; The electrogenic bacteria are inoculated into the anode reaction tank of the microbial fuel cell through the inoculation port, and sodium acetate solution is added and stirred. After the reaction is complete, normal operation begins. Every two days, all the supernatant is taken out, and an equal amount of sodium acetate solution is added to replenish it and stirred thoroughly. S4: Electric field-assisted cell dissolution. After the sludge flows into the electric field cell dissolution pool (11), the cell dissolution battery (14) releases electrical energy through the electrode head (15) in the electric field cell dissolution pool (11) to perform electric field-assisted cell dissolution pretreatment on the sludge. S5: Pulse feeding, the sludge in the electric field cell pool (11) is pumped into the cavity of the anode reaction pool (13) of the microbial fuel cell, stirred evenly, the cathode reaction pool is filled with clean water, and the anode reaction pool (13) and the cathode reaction pool of the microbial fuel cell are separated by a proton exchange membrane (18). S6: Power generation and sludge degradation. During the operation of the anode reaction tank (13) of the microbial fuel cell, the electrons generated by the reaction pass through the proton exchange membrane (18) and form a current between the charging wire (20) connecting the anode and the charging wire (22) connecting the cathode. The electrical energy is stored in the reverse current application device (23). After the voltage across the external resistor of the anode reaction tank (13) of the microbial fuel cell reaches the preset standard, wastewater degradation and power generation continue. S7: Anode self-cleaning. During the operation of the anode reaction tank (13) of the microbial fuel cell, the microbial fuel cell battery (23) applies a reverse voltage to the anode daily through the discharge wire (24) connected to the positive electrode and the discharge wire (25) connected to the negative electrode, causing the biofilm covering the anode surface to peel off. The gas pressure generated by the cathode reaction tank drives the CO2 generated by the reaction to enter the deoxygenation device (27) through the internal circulation air intake pipe (26). The CO2 absorbs the residual O2 through the sodium dithionite solution in the deoxygenation device (27), and then the pressure valve (28) is opened to allow CO2 to be introduced into the anode through the internal circulation exhaust pipe (29) for purging. The purging gas speed is controlled to cause the biofilm covering the anode surface to peel off. The pressure valve (28) controls the CO2 gas purging gas speed to be ≤0.1L / min, each purging lasts for 10 seconds, and the interval between each purging is 4 hours. S8: Sludge discharge and recycling. In the anode reaction tank (13) of the microbial fuel cell, when the voltage is lower than the minimum specified voltage, the bottom plate (32) of the anode reaction tank is opened, so that the biodegraded sludge enters the sludge recycling tank (33) for resource utilization and enters the next sludge treatment cycle.

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