Microbial fuel cell and apparatus

Abstract

The present application discloses a microbial fuel cell and equipment, wherein the cell comprises a cell body and a microbial carrier loaded with microorganisms, the cell body has a cavity for fuel liquid flow inside, the cell body is further provided with a water inlet and a water outlet connected to the cavity, the cell body comprises an anode and a cathode formed in the cavity, the microbial carrier is arranged in the cavity, and at least part of the microbial carrier is located between the anode and the cathode while at least part of the microbial carrier is in contact with the surface of the anode. The present application has simple structure, low cost and convenient use, can generate electricity by using sewage as fuel solution, and thus realizes resourceful treatment of sewage.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of battery, and particularly relates to a microbial fuel cell and equipment. BACKGROUND

[0002] Microbial fuel cell (MFC) is a device for directly converting chemical energy in organic matter into electrical energy by using microorganisms. The basic working principle is that in the anaerobic environment of the anode chamber, the organic matter is decomposed and releases electrons and protons under the action of microorganisms, the electrons are effectively transmitted between the biological components and the anode by means of a suitable electron transfer medium, and are transmitted to the cathode through an external circuit to form an electric current, while the protons are transmitted to the cathode through a proton exchange membrane, and the oxidant (generally oxygen) is reduced and combined with protons into water in the cathode. The traditional single-chamber microbial fuel cell (MFC) is composed of an anode chamber and an air cathode, and oxygen in the air is used as the final electron acceptor. The single-chamber MFC has the advantages of simple structure and low operation cost, but also has defects such as low electron output efficiency of the anode, low reaction rate of the cathode, and limited electrode materials due to the mutual influence of the anode and the cathode. SUMMARY

[0003] The present application aims to provide a microbial fuel cell and equipment, which has simple structure, low cost, and is easy to use, can produce electricity by using sewage as fuel solution, and thus realizes the resource treatment of sewage.

[0004] The microbial fuel cell of the present application comprises a cell body and a microbial carrier loaded with microorganisms, the cell body has a cavity for fuel liquid circulation inside, the cell body is further provided with a water inlet and a water outlet connected to the cavity, the cell body comprises an anode and a cathode formed in the cavity, the microbial carrier is arranged in the cavity, and at least part of the microbial carrier is located between the anode and the cathode while at least part of the microbial carrier is in contact with the surface of the anode.

[0005] In one improvement of the microbial fuel cell of the present application, the microbial carrier is obtained by enriching and culturing the electricity-generating microorganisms in a photocatalytic environment. Preferably, the electricity-generating microorganisms are obtained by inoculating activated sludge and culturing in a constant temperature and electric field environment.

[0006] In one improvement of the microbial fuel cell of the present application, the microbial carrier is obtained by enriching and culturing the electricity-generating microorganisms in a photocatalytic environment.

[0007] In one improvement of the microbial fuel cell of the present application, the microbial carrier is cotton yarn enriched with electricity-generating microorganisms.

[0008] In one improvement of the microbial fuel cell of the present application, the anode is a titanium-based titanium dioxide nanotube array composite material formed on a substrate.

[0009] One improvement of the microbial fuel cell of the present application is that the titanium-based titanium dioxide nanotube array composite material of the anode is formed with a titanium dioxide nanotube array on at least part of the surface of the titanium base.

[0010] One improvement of the microbial fuel cell of the present application is that the anode is a titanium metal structural member with a cavity, and a titanium dioxide nanotube array is formed on the outer wall of the cavity of the titanium metal structural member.

[0011] One improvement of the microbial fuel cell of the present application is that the cathode is a graphite electrode.

[0012] One improvement of the microbial fuel cell of the present application is that the cathode is a graphite cathode treated with acid or alkali.

[0013] One application device of the present application uses the microbial fuel cell as described above as a power supply or production / operation unit.

[0014] The single-compartment photocatalytic microbial fuel cell designed in the present application has simple required materials, low cost, and convenient operation, can produce electricity using sewage as fuel solution, and thus realizes resourceful treatment of sewage.

[0015] (1) The titanium-based titanium dioxide nanotube array material is used as the anode material of the battery, and the titanium dioxide nanotube array layer is located on the outside of the battery, so as to facilitate the reception of light to generate photo-generated electron-hole pairs and play the photoelectrocatalytic role; at the same time, the metal titanium surface layer is located inside the battery and directly contacts the electricity-producing microorganisms, which can not only promote the effective transmission of electrons generated by the oxidation of the fuel to the anode, but also reduce the potential damage of titanium dioxide to the biological cells, thus improving the electricity generation performance of the battery from multiple aspects.

[0016] (2) The electricity-producing microorganism selection scheme established in the present application uses an external voltage to generate an electric field between the electrode plates to induce and screen high-performance electricity-producing microorganisms. The use of semi-solid medium can make the anaerobic electricity-producing microorganisms more easily separated from other microorganisms during the screening process, so as to achieve the purpose of efficient selection. The light irradiation on the outer surface of the anode can induce and improve the adaptability of the electricity-producing microorganisms and produce more extracellular electrons to promote the current output of the anode of the battery. Moreover, since the electricity-producing microorganism membrane is closely attached to the anode, the battery is free from the use of a proton exchange membrane and has good feasibility.

[0017] (3) The cylindrical single-compartment microbial battery structure designed in the present application simultaneously realizes the light irradiation requirement of the photocatalytic anode and the requirement of sufficient contact between the cathode and air; and can greatly increase the effective electricity generation area of the anode in a smaller space, thereby saving equipment cost and improving the electricity generation capacity of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0019] Figure 1 is a schematic diagram of the internal structure of a microbial fuel cell in an embodiment of the present application;

[0020] Figure 2 is Figure 1 an external schematic diagram of the embodiment;

[0021] Figure 3 is Figure 1 a schematic diagram of the structure of the end cap in the embodiment;

[0022] Figure 4 is a colony state diagram of anaerobic electricity-producing microorganisms obtained by applying a voltage of 1.6V to the semi-solid culture medium;

[0023] Figure 5 is a cell concentration change curve in the liquid medium enrichment culture process;

[0024] Figure 6 is a biofilm formed on the inner surface of the anode adhering to the cotton yarn;

[0025] Figure 7 is an E-t curve of the photocatalytic microbial fuel cell operation;

[0026] Figure 8 is a P-R curve of the photocatalytic microbial fuel cell operation;

[0027] Figure 9 is a cyclic voltammetry curve of the photocatalytic microbial fuel cell operation. DETAILED DESCRIPTION

[0028] The present application will be described in detail below in conjunction with the embodiments. However, the embodiments do not limit the present application, and the changes in structure, method, or function made by those skilled in the art on the basis of the embodiments are included in the protection scope of the present application.

[0029] The electricity-producing microorganisms are activated sludge obtained from a treatment plant, which are screened, enriched, and cultured by the measures of the present application.

[0030] In an embodiment of the microbial fuel cell of the present application, the cell can include a cell body having a cavity inside for fuel liquid to flow through, and a microorganism carrier loaded with microorganisms, the cell body being provided with a water inlet and a water outlet communicating with the cavity, the fuel liquid flowing in the cavity to supply fuel to the anode and to facilitate the flow of the negative valence state oxygen element generated in the cathode and the oxidized state product of the fuel, the cell body including an anode and a cathode formed in the cavity, the microorganism carrier being arranged in the cavity to provide a suitable carrier and environment for the anaerobic microorganisms to attach and survive, and at least part of the microorganism carrier being located between the anode and the cathode while at least part of the microorganism carrier is in contact with the surface of the anode, the contact satisfying the transfer of electrons between the fuel component and the anode, forming the negative electrode of the cell, and forming a complete cell working circuit cycle through the combination of the cathode loaded back to the electrode with the oxygen element of the air.

[0031] The microorganism carrier is a carrier obtained by enriching and culturing the anaerobic electricity-producing microorganisms in a photocatalytic environment (here, the photocatalytic environment is an environment in which light is provided by a light source and a photo-induced electron-hole pair is generated by the titanium dioxide nanotube to make the electrode more efficient in obtaining electrons from the microorganism cells and outputting), and is generally made of a natural material of a fluffy or porous material, such as cotton, hemp or other natural fiber materials, to meet the needs of the growth and survival of the microorganisms. Preferably, the electricity-producing microorganisms are obtained by inoculating activated sludge and culturing in a constant temperature and electric field environment. Of course, in order to obtain sufficient number of bacteria, the electricity-producing microorganisms can also be multiplied. The multiplication can be obtained by applying a direct current voltage of 0.8-3.2V and placing in a 30°C constant temperature incubator. Of course, the culture medium can be a semi-solid culture medium containing 1g / L glucose, or other liquid or solid culture medium that meets the multiplication requirements. Preferably, the microorganism carrier is cotton yarn enriched with electricity-producing microorganisms.

[0032] In order to meet the working requirements of the cell, the anode is a titanium-based titanium dioxide nanotube array composite material formed on a substrate (here, the substrate can be a metal material or other non-metal material). Preferably, the titanium-based titanium dioxide nanotube array composite material of the anode is a titanium substrate having a titanium dioxide nanotube array formed on at least part of the surface. Further preferably, the anode is a titanium metal structural member having a cavity, and the titanium metal structural member has a titanium dioxide nanotube array formed on the outer wall of the cavity.

[0033] In addition, the cathode is a graphite electrode, which is in contact with air to supply the reduction reaction of oxygen in the air. Here, the cathode should be a graphite cathode treated with an appropriate concentration of acid or alkali. Preferably, the concentration of free hydrogen ions or free hydroxyl ions in the strong acid or strong base is not more than 0.2M.

[0034] In the implementation process of this solution, the following technical means can be specifically adopted:

[0035] Breeding plan for electricity-producing microorganisms: In a semi-solid simulated sewage medium containing 1 g / L glucose, two parallel titanium metal plates are vertically added and kept at a distance of 3 - 7 cm. The titanium plates are connected to the positive and negative electrodes of an external power supply through welded wires. Take activated sludge (activated sludge collected from a municipal sewage treatment plant) as the strain, and inoculate it by puncture into the medium at the midpoint between the two titanium electrodes. A DC voltage of 0.8 - 3.2 V is steadily and continuously applied to the titanium electrodes through the power supply. The voltage selection here depends on cultivation requirements. For example, 0.8 V, 3.2 V, 2 V, etc. can be selected, and various factors such as the activity or tolerance of the colonies can be considered. It is placed in an incubator at 30 °C for cultivation until anaerobic colonies grow out. The obtained anaerobic colonies are used as strains and inoculated into a simulated sewage liquid medium, and sealed and cultivated for 150 hours under the same above conditions to obtain an enriched culture solution of electricity-producing microorganisms.

[0036] Fabrication of the anode substrate material: After the pure titanium metal tube (with a diameter of d1) is polished and chemically polished, it is prepared into a titanium-based titanium dioxide nanotube array (Ti-TiO2NTs) composite material with a metal titanium inner wall layer and a TiO2 nanotube array outer wall layer by anodic oxidation treatment. Using conductive glue, a single-layer cotton yarn is tightly adhered to the inner wall of the Ti-TiO2NTs material to obtain the anode substrate tube.

[0037] Fabrication of the air cathode: After the graphite tube (with a diameter of d2, where d2 < d1) is soaked in dilute acid and alkali, it is connected to a wire through conductive glue as the air cathode support material.

[0038] Assembly of the battery cell body: Cut an acrylic plate into two rings of the same size, with an outer diameter of d1 and an inner diameter of d2, as shown in the end caps. Circular holes with a diameter of d3 (where 2d3 < (d1 - d2)) are respectively opened on them as the upper and lower sealing plates of the battery cell body. The upper and lower sealing plates, the Ti-TiO2NTs composite tube, and the graphite tube are镶嵌 together, and the joint is sealed with epoxy resin glue. The circular holes on the sealing plates are tightly plugged with rubber plugs with conduits to obtain the battery cell body, as shown in and. Figure 3 shown end caps, respectively open circular holes with a diameter of d3 (such that 2d3 < (d1 - d2)) on them as the upper and lower sealing plates of the battery cell body. Embed the upper and lower sealing plates, the Ti-TiO2NTs composite tube, and the graphite tube together, seal the joint with epoxy resin glue, and tightly plug the circular holes on the sealing plates with rubber plugs with conduits to obtain the battery cell body, as shown in and. Figure 1 and 2 shown.

[0039] Preparation of photocatalytic induced biofilm anode: the enriched culture solution of the selected electrogenic microorganism was circulated in the battery through the inlet and outlet of the sealing plate using a circulating pump, so that the electrogenic microorganism adhered to the inner wall of the anode pipe. The yarn adhered to the inner wall would greatly promote the adhesion and growth of the biofilm on the anode. When the biofilm was formed, the outer wall of the anode pipe was irradiated with a tungsten lamp, a xenon lamp or sunlight, so that the TiO2NTs generated photoinduced electron-hole pairs, which induced the electrogenic microorganism to better adapt to the anode material and promoted the electron transmission efficiency and current output of the battery. After the above conditions were maintained at 30°C for 5-7 days, the electrogenic microorganism biofilm adhered to the inner surface of the anode was obtained.

[0040] Construction and operating conditions of the photocatalytic microbial fuel cell: after the anode completed the biofilm formation, the wastewater to be treated was replaced by the enriched culture solution of the electrogenic microorganism and introduced into the battery. The cathode and anode of the battery were connected to a load or an electrochemical workstation through wires to form a closed loop, and the photocatalytic microbial fuel cell was constructed. The battery was kept under the same light conditions as the biofilm formation, and the battery was started to use the organic pollutants in the wastewater as fuel to realize wastewater treatment and power generation.

[0041] Specifically, the surface of a TA2 type industrial pure titanium circular cylinder with a diameter of 60 mm, a height of 100 mm and a thickness of 2 mm was polished and chemically polished, then anodized and annealed at 400°C to obtain a Ti-TiO2NTs composite material as an anode 01, as shown in Figure 1 and 2 The wires were spot-welded on the metal titanium side, and the single-layer cotton yarn was tightly adhered to the surface of the metal titanium using conductive glue. A graphite pipe with a diameter of 15 mm, a height of 100 mm and a thickness of 5 mm was immersed in 0.1 mol / L HCl and NaOH solutions for 24 h, respectively, and then washed and linked to the wires through conductive glue. The graphite pipe served as a cathode 02. The acrylic plate was cut into upper and lower sealing plates 03 of the same size as shown in Figure 3 At this time, it can be seen that the upper sealing plate has an upper cathode fixing hole and a drainage hole, and the lower sealing plate has a lower cathode fixing hole and a water inlet hole. The drainage hole and the water inlet hole correspond to the water hole 032. The water hole 032 is used to fix the cathode and connect the water inlet device and the drainage device. The drainage hole and the water inlet hole are respectively connected with a drainage joint 051 and a water inlet joint 042, which mainly play a sealing role. The drainage hole and the water inlet hole are respectively connected with a drainage pipe 052 and a water inlet pipe 041. The drainage pipe 052 and the water inlet pipe 041 are sealingly connected to the sealing plate through the drainage joint 051 and the water inlet joint 042. The Ti-TiO2NTs and the graphite pipe material are assembled into a closed battery cell body using epoxy resin glue.

[0042] Activated sludge microorganisms from the outlet of the aeration tank in a wastewater treatment plant were used as screening samples. Following the aforementioned method, semi-solid culture medium was used, and a voltage of 1.6V was applied to induce the selection of electrogenic microorganisms. After 10 days of cultivation, the anaerobic electrogenic microorganisms formed distinct colonies, such as... Figure 4 As shown in the figure. The obtained anaerobic colonies were inoculated into a liquid culture medium of the same composition and cultured under the same conditions. The cells reached their maximum concentration after 150 hours, yielding an enriched culture medium. Its growth curve is shown in the figure. Figure 5 As shown.

[0043] The obtained enriched culture medium of electrogenic microorganisms was circulated inside the battery through the inlet and outlet ports on the assembled battery sealing plate to form a biofilm. A 12W tungsten lamp was used to irradiate the outer wall of the anode, and the mixture was cultured at a constant temperature of 30°C for 120 hours, resulting in the formation of a biofilm on the inner surface of the anode. Figure 6 As shown in the figure. After the anode completes biofilm formation, the wastewater to be treated replaces the enriched culture medium of the electrogenic microorganisms and is introduced into the battery. The battery cathode and anode are connected to an electrochemical workstation via wires to form a closed circuit. The open-circuit voltage-time (Et) curve, power density-resistance (PR) curve, and cyclic voltammetry curve of the battery are measured, as shown in the figure. Figures 7-9 As shown in Table 1, the COD removal rate of the wastewater reached 64% after 12 hours of battery operation, compared to the original wastewater. The experimental results demonstrate that the photocatalytic microbial fuel cell designed and developed in this scheme is not only low-cost and easy to operate, but also has advantages such as short start-up cycle, stable power generation performance, and high COD removal rate.

[0044] Table 1. Changes in COD of wastewater before and after battery operation

[0045]

[0046] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0047] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A microbial fuel cell comprising a cell body having a cavity inside for a fuel liquid to flow therethrough, the cell body further having a water inlet and a water outlet communicating with the cavity, the cell body including an anode and a cathode formed inside the cavity, characterized in that, The microbial fuel cell further comprises a microbial carrier loaded with microorganisms, the microbial carrier is arranged in the cavity, and at least part of the microbial carrier is located between the anode and the cathode while at least part of the microbial carrier is in contact with the surface of the anode, the microorganisms are obtained by taking activated sludge as a strain, puncturing inoculation into a culture medium at a midpoint position between two titanium sheet electrodes, and culturing: after polishing and chemical polishing treatment of a TA2 type industrial pure titanium circular cylinder with a diameter of 60 mm, a height of 100 mm and a thickness of 2 mm, anodic oxidation and 400 DEG C annealing treatment are performed to obtain a Ti-TiO2 NTs composite material as an anode, a wire is spot-welded at the metal titanium side, and a single layer of cotton yarn is tightly adhered to the surface of the metal titanium by using conductive glue, a graphite pipe with a diameter of 15 mm, a height of 100 mm and a thickness of 5 mm is immersed in 0.1 mol / L HCl and NaOH solutions for 24 hours respectively, and then linked to the wire through conductive glue after cleaning, the graphite pipe is used as a cathode, and acrylic plates are cut into upper and lower sealing plates of the same size, the sealing plates are formed with a cathode fixing hole and a water hole, the upper sealing plate is formed with an upper cathode fixing hole and a drainage hole, the lower sealing plate is formed with a lower cathode fixing hole and a water inlet hole, the drainage hole and the water inlet hole correspond to the water hole, the water hole is used for fixing the cathode and connecting water inlet and drainage devices, the drainage hole and the water inlet hole are respectively connected with a drainage joint and a water inlet joint, the drainage joint and the water inlet joint mainly play a sealing role, the drainage hole and the water inlet hole are respectively connected with a drainage pipe and a water inlet pipe, and the drainage pipe and the water inlet pipe are sealingly connected to the sealing plate through the drainage joint and the water inlet joint, and the Ti-TiO2 NTs and the graphite pipe are assembled into a closed battery cell body by using epoxy resin glue; The activated sludge microorganisms at the outlet of an aeration tank of a sewage treatment plant are used as a screening sample, and the aforementioned semi-solid culture medium is used to induce and breed the electricity-producing microorganisms therein by applying a voltage of 1.6 V, and after 10 days of culture, the anaerobic electricity-producing microorganisms form obvious colonies, the obtained anaerobic colonies are used as a strain to inoculate into a liquid culture medium with the same composition, and the same conditions are used for culture, and the cell concentration reaches a maximum at 150 hours, and an enriched culture solution is obtained; The obtained electricity-producing microorganism enriched culture solution is circulated and flows in the battery interior through the water inlet and outlet on the assembled battery sealing plate, a 12 W tungsten lamp is used to irradiate the outer wall of the anode, a constant temperature state of 30 DEG C is maintained for 120 hours to form a biofilm on the inner surface of the anode, and after the anode completes the biofilm formation, the sewage to be treated is replaced by the electricity-producing microorganism enriched culture solution and is introduced into the battery.

2. Equipment, the microbial fuel cell is applied to the equipment of claim 1.

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