Microbial fuel cell self-driven microbial electrolysis cell system and application thereof

Abstract

The invention relates to the technical field of microbial electrochemistry, in particular to a microbial fuel cell self-driven microbial electrolysis cell system and application thereof. The microbial fuel cell self-driven microbial electrolysis cell system comprises a microbial electrolysis cell (MEC) and a microbial fuel cell (MFC) for supplying power to the MEC; an anode electrode of the MFC is a mixed strain immobilized modified carbon felt electrode, and a cathode electrode of the MFC is a modified carbon felt electrode; an anode electrode and a cathode electrode of the MEC are independently selected from one of a modified carbon felt electrode or a mixed strain immobilized modified carbon felt electrode; the mixed strain is a strain obtained by mixing shewanella and sludge bacteria; the anode electrode of the MEC is connected with the cathode electrode of the MFC, and the anode electrode of the MFC is connected with the cathode electrode of the MEC; the bipolar chambers of the MFC are both in an anaerobic state, and the bipolar chambers of the MEC are both in an anoxic state. The advantages of an MFC-MEC system are fully utilized, external power supply is not needed, the MFC supplies energy to the MEC to promote reverse flow of electrons, and electric energy is utilized in situ.

Description

Technical Field

[0001] The present invention relates to the field of microbial electrochemical technology, and in particular to a microbial fuel cell self-driven microbial electrolysis cell system and applications thereof. Background Art

[0002] Microbial fuel cells (MFCs) are energy conversion devices that combine the dual functions of sewage purification and electricity generation. They use the metabolic process of electroactive microorganisms to directly convert chemical energy in organic matter into electrical energy. They can generate electricity while removing organic matter. The microbial electrolysis cell (MEC) bioelectrochemical reactor is derived from MFC. It organically combines electroactive microorganisms with electrochemical systems, uses microorganisms to remove organic matter in wastewater, simultaneously treats wastewater and recovers energy, and overcomes the shortcomings of low efficiency and secondary pollution when purifying wastewater by traditional methods. MFC generates electricity by consuming chemical energy in organic matter, but the electricity it generates is small and unstable, making it difficult to store and use; and as a low-energy consumption system, MEC requires a certain amount of electricity to operate. Therefore, the electricity generated by MFC is used to drive the operation of MEC. This electrochemical system takes into account the dual needs of wastewater treatment and green energy. It is a bioelectrochemical process that can use microorganisms as catalysts to convert chemical energy into electrical energy, saving electrical energy storage equipment and reducing power loss, which largely solves the limitations of biotechnology in sewage engineering.

[0003] Patent CN 118156566 A discloses a method for repairing a heavy metal polluted environment with a microbial fuel cell. By adding immobilized bacterial particles, the microorganisms in the anode area can enhance the system voltage in a co-metabolism manner, providing electron acceptors or donors for the microorganisms. However, the immobilized particles used in this method have a complicated production process, cumbersome processing steps, and use of stainless steel mesh as an electrode material, which is too expensive and not suitable for industrial development. Patent CN 103588307A discloses a method for treating dye wastewater, in which MFC and MEC are connected in series, and MFC provides MEC with electricity for degrading dye wastewater, thereby improving the efficiency of using MFC alone to degrade dye wastewater. However, this method does not mention the treatment effect of the system on other pollutants in sewage, and the specific implementation effect is unknown. Patent CN 109052620A discloses a method for removing cadmium ions from heavy metal wastewater, in which a microbial fuel cell and a microbial electrolytic cell are connected in series to reduce and remove cadmium ions in heavy metal wastewater in the form of cadmium carbonate. However, this method connects MFC and MEC in series, and can only remove 83.3% of COD at most, and the pollutant removal effect needs to be improved.

[0004] Therefore, it is very important to provide a technical solution that can solve the above technical problems. Summary of the invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide a microbial fuel cell self-driven microbial electrolysis cell system and its application. The present invention utilizes coupled cultured Shewanella (electrogenic bacteria) and sludge bacteria to form a mixed bacterial community (new type of electrogenic bacterial community), and fixes the mixed bacterial community on a modified carbon felt electrode to achieve synergistic enhancement of the microbial fuel cell self-driven microbial electrolysis cell system (MFC-MEC system).

[0006] The MFC-MEC system of the present invention is an MFC-MEC bioelectrochemical system with good power generation effect and high pollutant removal rate. It has low production cost and can operate stably for a long time, creating powerful conditions for the large-scale application and promotion of the system in the field of wastewater treatment and promoting its commercial development.

[0007] The present invention makes full use of the advantages of the MFC-MEC system. No external power supply is required. The MFC supplies energy to the MEC to promote the reverse flow of electrons, so that the electric energy can be used in situ, and pollutants in the wastewater can be removed while reducing energy loss. It is an innovative wastewater treatment and energy recovery technology. Based on the MFC-MEC system, a method of synergistic enhancement of coupled cultivation of different strains is used. The mixed strains are firmly combined with the modified carbon felt electrode, and have strong resistance to water quality shock loads. It can shorten the enrichment time of the electrogenic bacteria, enhance the power generation performance of the MFC and the pollutant removal effect of the MEC, and its preparation method is simple, the investment cost is low, and the application prospects are broad.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] The first object of the present invention is to provide a microbial fuel cell self-driven microbial electrolysis cell system, comprising a microbial electrolysis cell and a microbial fuel cell for powering the microbial electrolysis cell;

[0010] The anode electrode of the microbial fuel cell is a modified carbon felt electrode with mixed bacterial species immobilized, and the cathode electrode is a modified carbon felt electrode; the anode electrode of the microbial electrolysis cell is selected from a modified carbon felt electrode or a modified carbon felt electrode with mixed bacterial species immobilized, and the cathode electrode of the microbial electrolysis cell is selected from a modified carbon felt electrode or a modified carbon felt electrode with mixed bacterial species immobilized;

[0011] Among them, the mixed bacterial species is a bacterial species obtained by mixing Shewanella and sludge bacteria; the sludge bacteria are selected from one or more of the genera Pseudomonas, Bacillus, Geobacter, Denitrifying Bacteria or Proteus; the present invention does not limit the specific bacterial species of the genera Pseudomonas, Bacillus, Geobacter, Denitrifying Bacteria and Proteus.

[0012] The anode electrode of the microbial electrolysis cell is connected to the cathode electrode of the microbial fuel cell through a first titanium wire, and the anode electrode of the microbial fuel cell is connected to the cathode electrode of the microbial electrolysis cell through a second titanium wire;

[0013] The anode chamber and cathode chamber of the microbial fuel cell are both in an anaerobic state (before assembling the microbial fuel cell, the anode chamber and cathode chamber must be purged with nitrogen and then continuously sealed with a rubber stopper), and the anode chamber and cathode chamber of the microbial electrolysis cell are both in an anoxic state (oxygen is continuously introduced into the two electrode chambers of the microbial electrolysis cell to maintain the dissolved oxygen concentration at 0.1-0.5 mg / L).

[0014] In one embodiment of the present invention, the anode chamber and cathode chamber of the microbial fuel cell are separated by a proton exchange membrane, and the anode chamber and cathode chamber of the microbial electrolysis cell are separated by a proton exchange membrane.

[0015] The anode chamber and cathode chamber of the microbial fuel cell are parallel and separated by 1 to 10 cm;

[0016] The anode chamber and cathode chamber of the microbial electrolysis cell are parallel and spaced 1 to 10 cm apart.

[0017] In one embodiment of the present invention, the proton exchange membrane is a CMI 7000 proton exchange membrane which is soaked in a 5-10 wt % sodium chloride solution for 12-48 hours and then rinsed with deionized water.

[0018] In one embodiment of the present invention, the modified carbon felt electrode is prepared by the following method:

[0019] The pretreated carbon felt is immersed in an acidic potassium dichromate solution, heated in a water bath, and then sequentially cleaned, dried, and calcined to obtain a modified carbon felt electrode.

[0020] In one embodiment of the present invention, the acidic potassium dichromate solution is a mixture of sulfuric acid and potassium dichromate solution; in the acidic potassium dichromate solution, the concentration of sulfuric acid is 1 to 3 mol / L, and the concentration of potassium dichromate is 0.2 to 0.6 mol / L;

[0021] During the water bath heating process, the temperature is 40-80°C and the time is 0.5-1h;

[0022] During the cleaning process, the carbon felt heated in a water bath was cleaned with deionized water until the pH was neutral;

[0023] During the drying process, the temperature is 60-120°C and the time is 2-24 hours;

[0024] The calcination process is carried out in an air atmosphere at a temperature of 300 to 600° C. and a time of 0.5 to 1.5 h.

[0025] In one embodiment of the present invention, the pretreatment process is as follows:

[0026] The carbon felt is placed in a hydrochloric acid solution, washed, placed in a sodium hydroxide solution, washed again, and then dried.

[0027] In one embodiment of the present invention, the concentration of the hydrochloric acid solution is 0.1 to 1 mol / L, and the immersion time in the hydrochloric acid solution is 6 to 36 hours;

[0028] The concentration of the sodium hydroxide is 0.1 to 1 mol / L, and the immersion time in the sodium hydroxide solution is 6 to 36 hours;

[0029] During the drying process, the temperature is 60-120°C and the time is 2-24h;

[0030] The carbon felt was washed until its pH was neutral.

[0031] In one embodiment of the present invention, the modified carbon felt electrode immobilized with mixed bacteria is prepared by the following method:

[0032] The modified carbon felt electrode is placed in LB culture medium, and then inoculated with a mixed bacterial solution of Shewanella and sludge bacteria. After the culture, the electrode is cleaned to obtain a modified carbon felt electrode with mixed bacterial species immobilized thereon.

[0033] In one embodiment of the present invention, during the culture process, the temperature is 20 to 45°C, the rotation speed is 100 to 220 rpm / min, the culture time is 3 to 10 days, and the LB medium is replaced every 12 to 48 hours;

[0034] During the cleaning process, the cleaning solution is a neutral phosphate buffer.

[0035] In one embodiment of the present invention, the mixed strains are prepared by the following method:

[0036] Take 5-400 mL of Shewanella culture liquid and 5-400 mL of sludge bacteria culture liquid respectively, mix them evenly, discard the supernatant after centrifugation, add 100-500 mL of fresh LB culture medium to obtain a mixed culture liquid of Shewanella and sludge bacteria, and place it in a shaker with a rotation speed of 100-220 rpm / min and a temperature of 20-45°C for standby use.

[0037] Wherein, the Shewanella bacterial liquid is prepared by the following method:

[0038] Under sterile conditions, the LB solid culture medium is heated and dissolved, and then poured into a culture dish to cool and solidify to obtain a solid culture medium;

[0039] After dissolving the Shewanella lyophilized powder with 1-10 mL of LB liquid culture medium, draw 0.05-0.1 mL of the mixed liquid culture medium onto the solid culture medium, spread it evenly with a coating rod, seal it with a sealing film, and invert and culture it at 20-45°C;

[0040] After the culture is completed, a single colony of Shewanella is picked up with an inoculation loop, streaked on a new solid culture medium for purification, sealed with a sealing film, and inverted at 20-45°C. A single colony is picked up and placed in LB liquid culture medium, and cultured in a shaker at a speed of 100-220 rpm / min and a temperature of 20-45°C to the end of the logarithmic phase to obtain a Shewanella bacterial solution.

[0041] The sludge bacteria liquid was prepared by the following method:

[0042] Under sterile conditions, the LB solid culture medium is heated and dissolved, and then poured into a culture dish to cool and solidify to obtain a solid culture medium;

[0043] Take 0.1-1 mL of sludge bacteria and dilute it with sterile saline for 10 6 ~10 8 After the mixture has been diluted to 200 μl, pipette 0.05-0.2 mL of the diluted bacterial solution onto the solid culture medium, spread the solution evenly with a spreading stick, let it stand for 0.1-1 h, and then invert and culture at 20-45°C.

[0044] After the cultivation is completed, a single colony of sludge bacteria is picked up with an inoculation loop, streaked on a new solid culture medium for purification, sealed with a sealing film, and inverted at 20-45°C. A single colony is picked up and placed in LB liquid culture medium, which is then placed in a shaker at a speed of 100-220 rpm / min and a temperature of 20-45°C and cultured to the end of the logarithmic phase to obtain a sludge bacteria liquid.

[0045] In one embodiment of the present invention, the first titanium wire and the second titanium wire are connected via an external resistor (resistance is 1 to 10000Ω).

[0046] In one embodiment of the present invention, the first titanium wire and the second titanium wire are titanium wires with a diameter of 0.2 to 1 mm.

[0047] The second object of the present invention is to provide an application of a microbial fuel cell self-driven microbial electrolysis cell system in wastewater treatment.

[0048] In one embodiment of the present invention, 15-35 mL of pretreated anaerobic activated sludge and 75-95 mL of wastewater are added to the anode chamber of the microbial fuel cell, and 90-110 mL of 0.05-0.2 mol / L potassium ferrocyanide solution is added to the cathode chamber;

[0049] 15-35 mL of pretreated anoxic activated sludge and 75-95 mL of wastewater are added to the anode chamber of the microbial electrolysis cell, and 15-35 mL of pretreated anoxic activated sludge and 75-95 mL of wastewater are added to the anode chamber.

[0050] In one embodiment of the present invention, the concentration of pre-treated anaerobic activated sludge is 3-30 g / L, and the concentration of pre-treated anoxic activated sludge is 1-10 g / L.

[0051] In one embodiment of the present invention, the pretreated anaerobic activated sludge is prepared by the following method:

[0052] The anaerobic sludge was filtered through a 50-200 mesh screen, and then an appropriate amount of simulated wastewater was added and stirred at room temperature for 24-72 hours to obtain pretreated anaerobic activated sludge.

[0053] Anoxic activated sludge is prepared by the following method:

[0054] Anoxic activated sludge acclimation is to continuously aerate the pretreated anaerobic activated sludge for 36 to 144 hours, maintain the dissolved oxygen content at 0.1 to 0.5 mg / L, and stir it at room temperature using an electric stirrer.

[0055] In one embodiment of the present invention, the simulated wastewater comprises the following components in concentration:

[0056] 1-30g / L sodium chloride, 0.5-15g / L sodium acetate, 0.1-2g / L ammonium chloride, 0.05-5g / L potassium dihydrogen phosphate, 0.05-5g / L dipotassium hydrogen phosphate, 0.05-3g / L potassium chloride, 1-20mL / L trace element solution, 1-20mL / L vitamin solution;

[0057] The trace element solution includes the following components in the following concentrations:

[0058] 1.5mg / L aminotriacetic acid, 3mg / L magnesium sulfate, 0.5mg / L manganese sulfate, 0.1mg / L ferrous sulfate, 0.01mg / L copper sulfate pentahydrate, 0.01mg / L potassium aluminum sulfate dodecahydrate, 0.01mg / L boric acid, 0.13mg / L zinc chloride, 1.0mg / L nickel chloride, 0.025mg / L sodium molybdate, 0.1mg / L cobalt chloride hexahydrate, 1.0mg / L sodium chloride, 2mg / L EDTA;

[0059] The vitamin solution includes the following components in the following concentrations:

[0060] 2mg / L Vitamin H, 5mg / L Vitamin B1, 5mg / L Vitamin B2, 5mg / L Vitamin B3, 5mg / L Vitamin B5, 10mg / L Vitamin B6, 2mg / L Vitamin B9, 0.1mg / L Vitamin B12, 5mg / L Zinc sulfate, 5mg / L P-aminobenzoic acid.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] (1) The present invention couples the cultivation of Shewanella and sludge bacteria, two types of bacteria with widely different characteristics, to form a new composite electrogenic bacterial community. Therefore, the resulting MFC has significantly improved electrogenic effect and can be applied to chemical wastewater scenarios.

[0063] (2) The cell immobilization technology is used to fix the above-mentioned electrogenic bacteria enriched and cultured by the method of the present invention onto the electrode with pre-surface modification, which has a significant bio-enhancement effect on the MFC system. The electrogenicity and pollutant removal effects of the MFC-MEC system have reached a higher level.

[0064] (3) The MFC-MEC system of the present invention has a simple and convenient operation process and low production cost. The MFC-MEC system has the advantages of high power generation efficiency and long power generation cycle, and has good prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 This is the MFC-MEC system installation diagram;

[0066] Figure 2 This is a diagram of the MFC voltage variation provided in Example 1;

[0067] Figure 3 The MFC current density and power density curves provided in Example 1;

[0068] Figure 4 This is a diagram showing the effect of MEC on COD removal provided in Example 1;

[0069] Figure 5 This is a diagram showing the effect of MEC removing TN provided in Example 1;

[0070] Figure 6 This is a diagram of the MFC voltage variation provided in Example 2;

[0071] Figure 7 The MFC current density and power density curves provided in Example 2;

[0072] Figure 8 This is a diagram showing the effect of MEC on COD removal provided in Example 2;

[0073] Fig. 9This is a diagram showing the effect of MEC removing TN provided in Example 2;

[0074] Fig.10 This is a diagram of the MFC voltage variation provided in Example 3;

[0075] Fig.11 The MFC current density and power density curves provided in Example 3;

[0076] Fig.12 This is a diagram showing the effect of MEC on COD removal provided in Example 3;

[0077] Fig.13 This is a diagram showing the COD removal effect of MEC provided in Example 3. DETAILED DESCRIPTION

[0078] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0079] Shewanella oneidensis is a commercially available strain purchased from the China Center for Type Culture Collection with a collection number of CCTCC AB 2013238; sludge bacteria are derived from mature engineered bacterial flora of a sewage treatment plant, including Pseudomonas, Bacillus, Geobacter, Denitrifying Bacteria, and Proteus.

[0080] Anaerobic sludge is anaerobic activated sludge taken from a chemical plant.

[0081] In the following examples, unless otherwise specified, all reagents used are commercially available reagents, and all detection means and methods used are conventional detection means and methods in the art.

[0082] Example 1

[0083] This embodiment provides an MFC-MEC system, and the preparation process is as follows:

[0084] (S1) Preparation of mixed strains:

[0085] (S101) The culture method of the Shewanella bacterial liquid is as follows:

[0086] Under sterile conditions, melt the LB solid medium and pour it into a culture dish to cool and solidify; dissolve the Shewanella lyophilized powder with 10 mL of LB liquid medium, and then draw 0.1 mL of the mixed liquid medium into the culture dish. After evenly spreading with a coating rod, seal it with a sealing film and invert it at 45°C. Pick a single colony of Shewanella with an inoculation loop, purify it by streaking on a solid culture dish, seal it with a sealing film, invert it at 45°C, pick a single colony and put it into LB liquid medium, and incubate it in a shaker at a speed of 220 rpm / min and a temperature of 45°C until the end of the logarithmic phase to obtain a Shewanella bacterial liquid.

[0087] (S102) The sludge bacteria liquid is cultured as follows: under sterile conditions, LB solid culture medium is melted and poured into a culture dish to cool and solidify; 1 mL of sludge bacteria is taken and diluted by 10% with sterile saline. 8 After 2 times, 0.05 mL of diluted bacterial solution was drawn into the culture dish, and the bacterial solution was evenly spread with a coating rod, and the culture was allowed to stand for 1 hour, and then inverted at 45°C to obtain a single colony of sludge bacteria. The single colony of sludge bacteria was picked up with an inoculation loop, and purified by streaking on a solid culture dish, which was sealed with a sealing film, and inverted at 45°C. A single colony was picked up and placed in LB liquid culture medium, and then placed in a shaking incubator with a speed of 220 rpm / min and a temperature of 45°C, and cultured to the end of the logarithmic phase to obtain a sludge bacteria solution.

[0088] (S103) The mixed strains are prepared by the following method:

[0089] Take 400 mL of Shewanella culture liquid and 400 mL of sludge bacteria culture liquid respectively, mix them evenly, discard the supernatant after centrifugation, add 500 mL of fresh LB culture medium to obtain a mixed culture liquid of Shewanella and sludge bacteria, and place it in a shaker at a speed of 220 rpm / min and a temperature of 45°C for use.

[0090] (S2) Preparation of modified carbon felt electrode:

[0091] The carbon felt with a thickness of 1 cm was immersed in a 1 mol / L hydrochloric acid solution for 6 hours, repeatedly rinsed with deionized water until neutral, then immersed in a 1 mol / L sodium hydroxide solution for 6 hours, repeatedly rinsed with deionized water until neutral, and then dried in an oven at 120°C for 2 hours to complete the pretreatment; the pretreated carbon felt was immersed in an acidic potassium dichromate solution containing 3 mol / L sulfuric acid (final concentration) and 0.6 mol / L potassium dichromate (final concentration), heated in a 40°C water bath for 1 hour, taken out and repeatedly rinsed with deionized water until neutral, placed in an oven at 120°C for 2 hours, then placed in a muffle furnace, heated at 600°C for 0.5 hours in an air atmosphere, and cooled to room temperature to obtain a modified carbon felt electrode.

[0092] (S3) Preparation of mixed bacterial immobilization modified carbon felt:

[0093] Place the modified carbon felt electrode prepared in step (S2) into 500 mL of sterile LB liquid culture medium, add 5 mL of the mixed bacterial solution prepared in step (S1) to fully immerse the carbon felt, and then culture it in a shaker at a speed of 220 rpm / min and a temperature of 45°C for 3 days. Add fresh LB liquid culture medium every 12 hours. After the culture is completed, wash the carbon felt with a neutral phosphate buffer solution to obtain a mixed bacterial species immobilized modified carbon felt.

[0094] (S4) Assembly of MFC and MEC:

[0095] MFC is a dual-chamber anaerobic structure, MEC is a dual-chamber anoxic structure, and the effective volume of the anode chamber and cathode chamber of MFC and the anode chamber and cathode chamber of MEC are both 115mL. To maintain the anaerobic conditions of MFC, before assembling MFC, the anode chamber and cathode chamber must be purged with nitrogen, and then continuously sealed with rubber stoppers; oxygen is continuously introduced into the anode chamber and cathode chamber of MEC to keep the dissolved oxygen content at 0.5mg / L to maintain the anoxic state of the two polar chambers.

[0096] The anode of MFC is the mixed bacteria immobilized modified carbon felt prepared in step (S3), and the cathode is the modified carbon felt electrode prepared in step (S2); the anode and cathode of MEC are both the mixed bacteria immobilized modified carbon felt prepared in step (S3); the anode and cathode of MFC and MEC are parallel and opposite and separated by 1 cm, and the size of each electrode is 4 cm×4 cm×1 cm. The anode chamber and cathode chamber of MFC and MEC are separated by a CMI 7000 proton exchange membrane that is soaked in 5wt% sodium chloride solution for 48 hours and then rinsed with deionized water;

[0097] During the test, 25 mL of pretreated anaerobic activated sludge and 75 mL of simulated wastewater were added to the anode chamber of the MFC, and 100 mL of 0.1 mol / L potassium ferrocyanide solution was added to the cathode chamber; 25 mL of pretreated anoxic activated sludge and 75 mL of simulated wastewater were added to both the anode chamber and the cathode chamber of the MEC. Figure 1 As shown in A, the anode electrode of MEC and the cathode electrode of MFC, and the anode electrode of MFC and the cathode electrode of MEC are connected by titanium wires with a diameter of 0.6 mm, and then connected by 10 4 A resistor of Ω is connected to the two titanium wires to form a closed loop (it is also possible to connect the two titanium wires without a resistor, such as Figure 1 B).

[0098] In this embodiment, the pretreated anaerobic activated sludge is prepared by the following method:

[0099] The anaerobic sludge was filtered with a 200-mesh screen, and then the simulated wastewater was added to the anaerobic sludge, and the mixture was sealed and stirred at room temperature for 72 hours using an electric stirrer to obtain pretreated anaerobic activated sludge with a concentration of 30 g / L;

[0100] The pretreated anoxic activated sludge was prepared by the following method:

[0101] The pretreated anaerobic activated sludge was continuously aerated for 144 hours to maintain a dissolved oxygen content of 0.5 mg / L, and was stirred at room temperature using an electric stirrer to obtain pretreated anoxic activated sludge with a concentration of 10 g / L.

[0102] The simulated wastewater includes the following components in concentration: 30 g / L sodium chloride, 15 g / L sodium acetate, 2 g / L ammonium chloride, 5 g / L potassium dihydrogen phosphate, 5 g / L potassium hydrogen phosphate, 3 g / L potassium chloride, 20 mL / L trace element solution, and 20 mL / L vitamin solution;

[0103] The trace element solution includes the following components in the following concentrations: 1.5 mg / L aminotriacetic acid, 3 mg / L magnesium sulfate, 0.5 mg / L manganese sulfate, 0.1 mg / L ferrous sulfate, 0.01 mg / L copper sulfate pentahydrate, 0.01 mg / L potassium aluminum sulfate dodecahydrate, 0.01 mg / L boric acid, 0.13 mg / L zinc chloride, 1.0 mg / L nickel chloride, 0.025 mg / L sodium molybdate, 0.1 mg / L cobalt chloride hexahydrate, 1.0 mg / L sodium chloride, and 2 mg / L EDTA;

[0104] The vitamin solution includes the following components in concentrations: 2 mg / L vitamin H, 5 mg / L vitamin B1, 5 mg / L vitamin B2, 5 mg / L vitamin B3, 5 mg / L vitamin B5, 10 mg / L vitamin B6, 2 mg / L vitamin B9, 0.1 mg / L vitamin B12, 5 mg / L zinc sulfate, and 5 mg / L P-aminobenzoic acid.

[0105] The MFC-MEC system was placed in a 45°C constant temperature incubator, and the output voltage of the MFC was monitored using the Lanbo voltage test system (BT 2018C Hubei Lanbo New Energy Equipment Co., Ltd.). The voltage value was collected every 5 minutes and the data was automatically saved (e.g. Figure 2 shown); through Figure 2 It can be found that the maximum voltage is 767.72mV, the continuous and stable power generation is 259.27h, and the power generation cycle is 335.92h.

[0106] The polarization curve is a curve drawn for different power densities under different current densities. The external resistor is replaced by a resistor box, and the resistance value is changed to 10000, 8000, 6000, 4000, 2000, 1000, 800, 600, 400, 200, 100Ω respectively. The data is recorded after the voltage stabilizes. The current density and power density curves are calculated and drawn by the voltage values ​​corresponding to different external resistance values. The current density and power density are calculated according to I = U / (R×A), P = UI, where R is the external resistor value and A is the electrode area (the results are shown in Figure 2). Figure 3 shown); through Figure 3 It can be found that the maximum power density of MFC is 801.79mW / m 2 .

[0107] The COD and TN concentrations in the anode and cathode chambers of the MFC were measured every 24 hours (the results are shown in Figure 4 and Figure 5 ). Figure 4 It can be found that the highest COD removal rate in the anode chamber of MEC is 91.18%, and the COD removal rate in the cathode chamber is 97.96%; Figure 5 It can be found that the highest TN removal efficiency in the anode chamber of MEC is 90.15%, and the TN removal efficiency in the cathode chamber is 99.09%.

[0108] Example 2

[0109] This embodiment provides an MFC-MEC system, and the preparation process is as follows:

[0110] (S1) Preparation of mixed strains:

[0111] (S101) The culture method of the Shewanella bacterial liquid is as follows:

[0112] Under sterile conditions, melt the LB solid medium and pour it into a culture dish to cool and solidify; dissolve the Shewanella lyophilized powder with 5 mL of LB liquid medium, and then pipette 0.075 mL of the mixed liquid medium into the culture dish. After evenly coating with a coating rod, seal it with a sealing film and invert it at 32°C. Pick a single colony of Shewanella with an inoculation loop, purify it by streaking on a solid culture dish, seal it with a sealing film, invert it at 32°C, pick a single colony and put it into LB liquid medium, and incubate it in a shaker at a speed of 150 rpm / min and a temperature of 32°C until the end of the logarithmic phase to obtain a Shewanella bacterial liquid.

[0113] (S102) The sludge bacterial culture liquid is cultured as follows: under sterile conditions, LB solid culture medium is melted and poured into a culture dish to cool and solidify; 0.075 mL of sludge liquid bacterial culture liquid is taken and diluted by 10% with sterile saline. 8 After 10 times, 0.1 mL of diluted bacterial solution was drawn into the culture dish, and the bacterial solution was evenly spread with a coating rod, and then allowed to stand for 0.5 h. The culture dish was inverted at 32°C to obtain a single colony of sludge bacteria. A single colony of sludge bacteria was picked up with an inoculation loop, and purified by streaking on a solid culture dish, which was sealed with a sealing film. After inverted culture at 32°C, a single colony was picked up and placed in LB liquid culture medium, and then placed in a shaking incubator at a speed of 150 rpm / min and a temperature of 32°C, and cultured to the end of the logarithmic phase to obtain a sludge bacterial solution.

[0114] (S103) The mixed strains are prepared by the following method:

[0115] Take 200 mL of Shewanella culture liquid and 200 mL of sludge bacteria culture liquid respectively, mix them evenly, discard the supernatant after centrifugation, add 300 mL of fresh LB culture medium to obtain a mixed culture liquid of Shewanella and sludge bacteria, and place it in a shaker at a speed of 150 rpm / min and a temperature of 32°C for use.

[0116] (S2) Preparation of modified carbon felt electrode:

[0117] The carbon felt with a thickness of 1 cm was immersed in a 0.5 mol / L hydrochloric acid solution for 24 hours, repeatedly rinsed with deionized water until neutral, then immersed in a 0.5 mol / L sodium hydroxide solution for 24 hours, repeatedly rinsed with deionized water until neutral, and then placed in an oven at 90°C for 12 hours to complete the pretreatment; the pretreated carbon felt was immersed in an acidic potassium dichromate solution containing 2 mol / L sulfuric acid (final concentration) and 0.4 mol / L potassium dichromate (final concentration), heated in a 60°C water bath for 0.75 hours, taken out and repeatedly rinsed with deionized water until neutral, placed in an oven at 60°C for 12 hours, then placed in a muffle furnace, heated at 450°C for 1 hour in an air atmosphere, and cooled to room temperature to obtain a modified carbon felt electrode.

[0118] (S3) Preparation of mixed bacterial immobilization modified carbon felt:

[0119] Place the modified carbon felt electrode prepared in step (S2) into 250 mL of sterile LB liquid culture medium, add 1 mL of the mixed bacteria prepared in step (S1) to fully immerse the carbon felt, and then culture it in a shaker at a speed of 150 rpm / min and a temperature of 32°C for 6 days. Add fresh LB liquid culture medium every 24 hours. After the culture is completed, wash the carbon felt with a neutral phosphate buffer solution to obtain a mixed bacteria-immobilized modified carbon felt.

[0120] (S4) Assembly of MFC and MEC:

[0121] MFC is a dual-chamber anaerobic structure, MEC is a dual-chamber anoxic structure, and the effective volume of the anode chamber and cathode chamber of MFC and the anode chamber and cathode chamber of MEC are both 115mL. To maintain the anaerobic conditions of MFC, before assembling MFC, the anode chamber and cathode chamber must be purged with nitrogen, and then continuously sealed with rubber stoppers; oxygen is continuously introduced into the anode chamber and cathode chamber of MEC to keep the dissolved oxygen content at 0.3mg / L to maintain the anoxic state of the two polar chambers.

[0122] Wherein, the anode of MFC is the mixed bacteria immobilized modified carbon felt prepared in step (S3), and the cathode is the modified carbon felt electrode prepared in step (S2); the anode of MEC is the modified carbon felt electrode prepared in step (S2), and the cathode is the mixed bacteria immobilized modified carbon felt prepared in step (S3); the anode and cathode of MFC and MEC are parallel and opposite and separated by 5 cm, and the size of each electrode is 4 cm×4 cm×1 cm. The anode chamber and cathode chamber of MFC and MEC are separated by a CMI 7000 proton exchange membrane that is soaked in 7wt% sodium chloride solution for 30 hours and then rinsed with deionized water;

[0123] During the test, 25 mL of pretreated anaerobic activated sludge and 75 mL of simulated wastewater were added to the anode chamber of the MFC, and 100 mL of 0.1 mol / L potassium ferrocyanide solution was added to the cathode chamber; 25 mL of pretreated anoxic activated sludge and 75 mL of simulated wastewater were added to both the anode chamber and the cathode chamber of the MEC. Figure 1 As shown, the anode electrode of MEC and the cathode electrode of MFC, and the anode electrode of MFC and the cathode electrode of MEC are respectively connected through a titanium wire with a diameter of 0.9 mm, and then the two titanium wires are connected with a resistor of 5000Ω to form a closed loop.

[0124] In this embodiment, the pretreated anaerobic activated sludge is prepared by the following method:

[0125] The anaerobic sludge was filtered with a 200-mesh screen, and then the simulated wastewater was added to the anaerobic sludge, and the mixture was sealed and stirred at room temperature for 48 hours using an electric stirrer to obtain pretreated anaerobic activated sludge with a concentration of 20 g / L;

[0126] The pretreated anoxic activated sludge was prepared by the following method:

[0127] The pretreated anaerobic activated sludge was continuously aerated for 90 hours to maintain a dissolved oxygen content of 0.3 mg / L, and was stirred at room temperature using an electric stirrer to obtain pretreated anoxic activated sludge with a concentration of 5 g / L.

[0128] The simulated wastewater includes the following components at the following concentrations: 15 g / L sodium chloride, 10 g / L sodium acetate, 1 g / L ammonium chloride, 2.5 g / L potassium dihydrogen phosphate, 2.5 g / L potassium hydrogen phosphate, 1.5 g / L potassium chloride, 10 mL / L trace element solution, and 10 mL / L vitamin solution;

[0129] The trace element solution includes the following components in the following concentrations: 1.5 mg / L aminotriacetic acid, 3 mg / L magnesium sulfate, 0.5 mg / L manganese sulfate, 0.1 mg / L ferrous sulfate, 0.01 mg / L copper sulfate pentahydrate, 0.01 mg / L potassium aluminum sulfate dodecahydrate, 0.01 mg / L boric acid, 0.13 mg / L zinc chloride, 1.0 mg / L nickel chloride, 0.025 mg / L sodium molybdate, 0.1 mg / L cobalt chloride hexahydrate, 1.0 mg / L sodium chloride, and 2 mg / L EDTA;

[0130] The vitamin solution includes the following components in concentrations: 2 mg / L vitamin H, 5 mg / L vitamin B1, 5 mg / L vitamin B2, 5 mg / L vitamin B3, 5 mg / L vitamin B5, 10 mg / L vitamin B6, 2 mg / L vitamin B9, 0.1 mg / L vitamin B12, 5 mg / L zinc sulfate, and 5 mg / L P-aminobenzoic acid.

[0131] The MFC-MEC system was placed in a 32°C constant temperature incubator, and the output voltage of the MFC was monitored using the Lanbo voltage test system (BT 2018C Hubei Lanbo New Energy Equipment Co., Ltd.). The voltage value was collected every 5 minutes and the data was automatically saved (e.g. Figure 6 shown); through Figure 6 It can be found that the maximum voltage is 701.87mV, the continuous and stable power generation is 196.82h, and the power generation cycle is 295.23h.

[0132] The polarization curve is a curve drawn for different power densities under different current densities. The external resistor is replaced by a resistor box, and the resistance value is changed to 10000, 8000, 6000, 4000, 2000, 1000, 800, 600, 400, 200, 100Ω respectively. The data is recorded after the voltage stabilizes. The current density and power density curves are calculated and drawn by the voltage values ​​corresponding to different external resistance values. The current density and power density are calculated according to I = U / (R×A), P = UI, where R is the external resistor value and A is the electrode area (the results are shown in Figure 2). Figure 7 shown); through Figure 7 It can be found that the maximum power density of MFC is 614.20mW / m 2 .

[0133] The COD and TN concentrations in the anode and cathode chambers of the MFC were measured every 24 hours (the results are shown in Figure 8 and Fig. 9 ). Figure 8 It can be found that the highest COD removal rate in the anode chamber of MEC is 86.91%, and the COD removal rate in the cathode chamber is 92.66%; Fig. 9 It can be found that the highest TN removal efficiency is 88.23% in the anode chamber of MEC, and the TN removal efficiency in the cathode chamber is 89.07%.

[0134] Example 3

[0135] This embodiment provides an MFC-MEC system, and the preparation process is as follows:

[0136] (S1) Preparation of mixed strains:

[0137] (S101) The culture method of the Shewanella bacterial liquid is as follows:

[0138] Under sterile conditions, melt the LB solid medium and pour it into a culture dish to cool and solidify; dissolve the Shewanella lyophilized powder with 1 mL of LB liquid medium, pipette 0.05 mL of the mixed liquid medium into the culture dish, spread it evenly with a coating rod, seal it with a sealing film, and invert it at 20°C. Pick a single colony of Shewanella with an inoculation loop, purify it by streaking on a solid culture dish, seal it with a sealing film, invert it at 20°C, pick a single colony and put it into LB liquid medium, and culture it in a shaker at a speed of 100 rpm / min and a temperature of 20°C until the end of the logarithmic phase to obtain a Shewanella bacterial liquid.

[0139] (S102) The sludge bacterial liquid is cultured as follows: under sterile conditions, LB solid culture medium is melted and poured into a culture dish to cool and solidify; 0.1 mL of sludge liquid bacterial liquid is taken and diluted by 10% with sterile saline. 6 After 2 times, 0.05 mL of diluted bacterial solution was drawn into the culture dish, and the bacterial solution was evenly spread with a coating rod, and then allowed to stand for 0.1 h. The culture dish was inverted at 20°C to obtain a single colony of sludge bacteria. A single colony of sludge bacteria was picked up with an inoculation loop, and purified by streaking on a solid culture dish, which was sealed with a sealing film. After inverted culture at 20°C, a single colony was picked up and placed in LB liquid culture medium, and then placed in a shaking incubator at a speed of 100 rpm / min and a temperature of 20°C, and cultured to the end of the logarithmic phase to obtain a sludge bacteria solution.

[0140] (S103) The mixed strains are prepared by the following method:

[0141] Take 5 mL of Shewanella culture liquid and 5 mL of sludge bacteria culture liquid respectively, mix them evenly, discard the supernatant after centrifugation, add 100 mL of fresh LB culture medium to obtain a mixed culture liquid of Shewanella and sludge bacteria, and place it in a shaker at a speed of 100 rpm / min and a temperature of 20°C for use.

[0142] (S2) Preparation of modified carbon felt electrode:

[0143] The carbon felt with a thickness of 1 cm was immersed in a 0.1 mol / L hydrochloric acid solution for 36 hours, repeatedly rinsed with deionized water until neutral, then immersed in a 0.1 mol / L sodium hydroxide solution for 36 hours, repeatedly rinsed with deionized water until neutral, and then placed in an oven at 60°C for 24 hours to complete the pretreatment; the pretreated carbon felt was immersed in an acidic potassium dichromate solution containing 1 mol / L sulfuric acid (final concentration) and 0.2 mol / L potassium dichromate (final concentration), heated in an 80°C water bath for 0.5 hours, taken out and repeatedly rinsed with deionized water until neutral, placed in an oven at 60°C for 24 hours, then placed in a muffle furnace, heated at 300°C for 1.5 hours in an air atmosphere, and cooled to room temperature to obtain a modified carbon felt electrode.

[0144] (S3) Preparation of mixed bacterial immobilization modified carbon felt:

[0145] Place the modified carbon felt electrode prepared in step (S2) into 50 mL of sterile LB liquid culture medium, add 50 μL of the mixed bacteria prepared in step (S1) to fully immerse the carbon felt, and then culture it in a shaker at a speed of 100 rpm / min and a temperature of 20°C for 10 days. Add fresh LB liquid culture medium every 48 hours. After the culture is completed, wash the carbon felt with neutral phosphate buffer to obtain a modified carbon felt with mixed bacteria immobilized.

[0146] (S4) Assembly of MFC and MEC:

[0147] MFC is a dual-chamber anaerobic structure, MEC is a dual-chamber anoxic structure, and the effective volume of the anode chamber and cathode chamber of MFC and the anode chamber and cathode chamber of MEC are both 115mL. In order to maintain the anaerobic conditions of MFC, before assembling MFC, the anode chamber and cathode chamber must be purged with nitrogen, and then continuously sealed with rubber stoppers; oxygen is continuously introduced into the anode chamber and cathode chamber of MEC to keep the dissolved oxygen content at 0.1mg / L to maintain the anoxic state of the two polar chambers.

[0148] The anode of MFC is the mixed bacteria immobilized modified carbon felt prepared in step (S3), and the cathode is the modified carbon felt electrode prepared in step (S2); the anode of MEC is the mixed bacteria immobilized modified carbon felt prepared in step (S3), and the cathode is the modified carbon felt electrode prepared in step (S2); the anode and cathode of MFC and MEC are parallel and opposite and separated by 10 cm, and the size of each electrode is 4 cm×4 cm×1 cm. The anode chamber and cathode chamber of MFC and MEC are separated by a CMI 7000 proton exchange membrane that is soaked in 10wt% sodium chloride solution for 12 hours and then rinsed with deionized water;

[0149] During the test, 25 mL of pretreated anaerobic activated sludge and 75 mL of simulated wastewater were added to the anode chamber of the MFC, and 100 mL of 0.1 mol / L potassium ferrocyanide solution was added to the cathode chamber; 25 mL of pretreated anoxic activated sludge and 75 mL of simulated wastewater were added to both the anode chamber and the cathode chamber of the MEC. Figure 1 As shown, the anode electrode of the MEC and the cathode electrode of the MFC, and the anode electrode of the MFC and the cathode electrode of the MEC are respectively connected through a titanium wire with a diameter of 1.2 mm, and a resistor of 1Ω connects the two titanium wires to form a closed loop.

[0150] In this embodiment, the pretreated anaerobic activated sludge is prepared by the following method:

[0151] The anaerobic sludge was filtered with a 200-mesh screen, and then the simulated wastewater was added to the anaerobic sludge, and the mixture was sealed and stirred at room temperature for 24 hours using an electric stirrer to obtain pretreated anaerobic activated sludge with a concentration of 3 g / L;

[0152] The pretreated anoxic activated sludge was prepared by the following method:

[0153] The pretreated anaerobic activated sludge was continuously aerated for 36 hours to maintain a dissolved oxygen content of 0.1 mg / L, and was stirred at room temperature using an electric stirrer to obtain pretreated anoxic activated sludge with a concentration of 1 g / L.

[0154] The simulated wastewater includes the following components in concentration: 1 g / L sodium chloride, 0.5 g / L sodium acetate, 0.1 g / L ammonium chloride, 0.05 g / L potassium dihydrogen phosphate, 0.05 g / L potassium hydrogen phosphate, 0.05 g / L potassium chloride, 1 mL / L trace element solution, and 1 mL / L vitamin solution;

[0155] The trace element solution includes the following components in the following concentrations: 1.5 mg / L aminotriacetic acid, 3 mg / L magnesium sulfate, 0.5 mg / L manganese sulfate, 0.1 mg / L ferrous sulfate, 0.01 mg / L copper sulfate pentahydrate, 0.01 mg / L potassium aluminum sulfate dodecahydrate, 0.01 mg / L boric acid, 0.13 mg / L zinc chloride, 1.0 mg / L nickel chloride, 0.025 mg / L sodium molybdate, 0.1 mg / L cobalt chloride hexahydrate, 1.0 mg / L sodium chloride, and 2 mg / L EDTA;

[0156] The vitamin solution includes the following components in concentrations: 2 mg / L vitamin H, 5 mg / L vitamin B1, 5 mg / L vitamin B2, 5 mg / L vitamin B3, 5 mg / L vitamin B5, 10 mg / L vitamin B6, 2 mg / L vitamin B9, 0.1 mg / L vitamin B12, 5 mg / L zinc sulfate, and 5 mg / L P-aminobenzoic acid.

[0157] The MFC-MEC system was placed in a 20°C constant temperature incubator, and the output voltage of the MFC was monitored using the Lanbo voltage test system (BT 2018C Hubei Lanbo New Energy Equipment Co., Ltd.). The voltage value was collected every 5 minutes and the data was automatically saved (e.g. Fig.10 shown); through Fig.10 It can be found that the maximum voltage is 628.95mV, the continuous and stable power generation is 168.62h, and the power generation cycle is 266.89h.

[0158] The polarization curve is a curve drawn for different power densities under different current densities. The external resistor is replaced by a resistor box, and the resistance value is changed to 10000, 8000, 6000, 4000, 2000, 1000, 800, 600, 400, 200, 100Ω respectively. The data is recorded after the voltage stabilizes. The current density and power density curves are calculated and drawn by the voltage values ​​corresponding to different external resistance values. The current density and power density are calculated according to I = U / (R×A), P = UI, where R is the external resistor value and A is the electrode area (the results are shown in Figure 2). Fig.11 shown); through Fig.11 It can be found that the maximum power density of MFC is 534.44mW / m 2 .

[0159] The COD and TN concentrations in the anode and cathode chambers of the MFC were measured every 24 hours (the results are shown in Fig.12 and Fig.13 ). Fig.12 It can be found that the highest COD removal rate in the anode chamber of MEC is 77.22%, and the COD removal rate in the cathode chamber is 79.99%; Fig.13 It can be found that the highest TN removal efficiency is 85.60% in the anode chamber of MEC, and the TN removal efficiency in the cathode chamber is 75.47%.

[0160] Comparative Example 1

[0161] This comparative example is the same as Example 1 except for the following contents:

[0162] The mixed bacteria immobilized modified carbon felt electrode was replaced with a Shewanella immobilized modified carbon felt electrode.

[0163] The Shewanella immobilized modified carbon felt electrode was prepared by the following method:

[0164] Place the modified carbon felt electrode into 500 mL of sterile LB liquid culture medium, add 5 mL of Shewanella bacterial solution to fully immerse the carbon felt, and then culture it in a shaker at 220 rpm / min and 45°C for 3 days. Add fresh LB liquid culture medium every 12 hours. After the culture, wash the carbon felt with neutral phosphate buffer to obtain a mixed bacterial species immobilized modified carbon felt.

[0165] Comparative Example 2

[0166] This comparative example is the same as Example 1 except for the following contents:

[0167] The mixed bacteria immobilized modified carbon felt electrode was replaced with a sludge bacteria immobilized modified carbon felt electrode.

[0168] The sludge bacteria immobilized modified carbon felt electrode was prepared by the following method:

[0169] Place the modified carbon felt electrode into 500 mL of sterile LB liquid culture medium, add 5 mL of sludge bacteria liquid to fully immerse the carbon felt, and then culture it in a shaker at 220 rpm / min and 45 °C for 3 days. Add fresh LB liquid culture medium every 12 hours. After the culture, wash the carbon felt with neutral phosphate buffer to obtain a mixed bacterial species immobilized modified carbon felt.

[0170] The maximum power generation voltage and continuous power generation time of the MFC of Example 1, Comparative Example 1 and Comparative Example 2, as well as the COD and TN removal effects of the anode chamber and cathode chamber of the MFC are shown in Table 1.

[0171] Table 1 Performance summary

[0172]

[0173]

[0174] It can be found from Table 1 that compared with the single Shewanella immobilized modified carbon felt electrode and the single sludge bacteria immobilized modified carbon felt electrode, the power generation performance of the MFC using the mixed bacteria immobilized modified carbon felt electrode is significantly enhanced, and the continuous power generation time is increased. The MEC using the mixed bacteria immobilized modified carbon felt electrode has significantly improved the removal effect of COD and TN in wastewater, and it is found that Shewanella and sludge bacteria have a synergistic effect.

[0175] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the explanation of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A microbial fuel cell self-driven microbial electrolysis cell system, characterized in that: It includes a microbial electrolysis cell and a microbial fuel cell for powering the microbial electrolysis cell; The anode electrode of the microbial fuel cell is a modified carbon felt electrode with mixed bacterial species immobilized, and the cathode electrode is a modified carbon felt electrode; the anode electrode of the microbial electrolysis cell is selected from a modified carbon felt electrode or a modified carbon felt electrode with mixed bacterial species immobilized, and the cathode electrode of the microbial electrolysis cell is selected from a modified carbon felt electrode or a modified carbon felt electrode with mixed bacterial species immobilized; The mixed bacteria are obtained by mixing Shewanella and sludge bacteria; the sludge bacteria are selected from one or more of the genera Pseudomonas, Bacillus, Geobacter, Denitrifying Bacteria or Proteus; The anode electrode of the microbial electrolysis cell is connected to the cathode electrode of the microbial fuel cell through a first titanium wire, and the anode electrode of the microbial fuel cell is connected to the cathode electrode of the microbial electrolysis cell through a second titanium wire; The anode chamber and cathode chamber of the microbial fuel cell are both in anaerobic state, and the anode chamber and cathode chamber of the microbial electrolysis cell are both in anoxic state.

2. A microbial fuel cell self-driven microbial electrolysis cell system according to claim 1, characterized in that: The anode chamber and cathode chamber of the microbial fuel cell are separated by a proton exchange membrane, and the anode chamber and cathode chamber of the microbial electrolysis cell are separated by a proton exchange membrane.

3. The microbial fuel cell self-driven microbial electrolysis cell system according to claim 1, characterized in that: The modified carbon felt electrode is prepared by the following method: The pretreated carbon felt is immersed in an acidic potassium dichromate solution, heated in a water bath, and then sequentially cleaned, dried, and calcined to obtain a modified carbon felt electrode.

4. A microbial fuel cell self-driven microbial electrolysis cell system according to claim 3, characterized in that: The acidic potassium dichromate solution is a mixture of sulfuric acid and potassium dichromate solution; in the acidic potassium dichromate solution, the concentration of sulfuric acid is 1-3 mol / L, and the concentration of potassium dichromate is 0.2-0.6 mol / L; During the water bath heating process, the temperature is 40-80°C and the time is 0.5-1h; During the cleaning process, the carbon felt heated in a water bath was cleaned with deionized water until the pH was neutral; During the drying process, the temperature is 60-120°C and the time is 2-24 hours; The calcination process is carried out in an air atmosphere at a temperature of 300 to 600° C. and a time of 0.5 to 1.5 h.

5. The microbial fuel cell self-driven microbial electrolysis cell system according to claim 3, characterized in that: The preprocessing process is as follows: The carbon felt is placed in a hydrochloric acid solution, washed, placed in a sodium hydroxide solution, washed again, and then dried.

6. A microbial fuel cell self-driven microbial electrolysis cell system according to claim 5, characterized in that: The concentration of the hydrochloric acid solution is 0.1 to 1 mol / L, and the immersion time in the hydrochloric acid solution is 6 to 36 hours; The concentration of the sodium hydroxide is 0.1 to 1 mol / L, and the immersion time in the sodium hydroxide solution is 6 to 36 hours; During the drying process, the temperature is 60-120°C and the time is 2-24h; The carbon felt was washed until its pH was neutral.

7. The microbial fuel cell self-driven microbial electrolysis cell system according to claim 5, characterized in that: The modified carbon felt electrode with mixed bacterial species immobilized was prepared by the following method: The modified carbon felt electrode is placed in LB culture medium, and then inoculated with a mixed bacterial solution of Shewanella and sludge bacteria. After the culture, the electrode is cleaned to obtain a modified carbon felt electrode with mixed bacterial species immobilized thereon.

8. The microbial fuel cell self-driven microbial electrolysis cell system according to claim 7, characterized in that: During the culture process, the temperature is 20-45°C, the rotation speed is 100-220 rpm / min, the culture time is 3-10 days, and the LB medium is replaced every 12-48 hours.

9. The microbial fuel cell self-driven microbial electrolysis cell system according to claim 1, characterized in that: The first titanium wire and the second titanium wire are connected via an external resistor.

10. Use of the microbial fuel cell self-driven microbial electrolysis cell system according to any one of claims 1 to 9 in wastewater treatment.

Images