Pipe-type microbial fuel cell and piping system

Abstract

To make it possible to generate electricity using plumbing pipes.SOLUTION: A piping-type microbial fuel cell disclosed herein includes a pipe body through which a liquid flows, one or more anodes provided on the inner surface of the pipe body, and one or more cathodes provided on the inner surface of the pipe body.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to plumbing pipe microbial fuel cells and plumbing systems. [Background technology]

[0002] Patent Document 1 discloses a microbial fuel cell. A microbial fuel cell is a device that uses the metabolic reaction of microorganisms to convert organic fuel into electrical energy and generate electricity. The microbial fuel cell is equipped with an anode electrode and a cathode electrode as electrodes. In the microbial fuel cell, electrons generated when organic fuel is decomposed by microorganisms are collected at the anode electrode and transferred from the anode electrode to the cathode electrode via an external circuit. In addition, protons generated at the anode electrode react with the electrons transferred to the cathode electrode and oxygen to produce water. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-117743 A Summary of the Invention

[0004] Conventionally, it has not been done to install a microbial fuel cell inside a piping system. If a microbial fuel cell is installed inside a piping system through which liquids such as waste liquid flow, it will be possible to generate electricity using the liquids such as waste liquid inside the pipe. It will also be possible to purify the waste liquid inside the pipe. It will also be possible to use a microbial fuel cell as a sensor to measure the amount of organic matter in the pipe.

[0005] Therefore, in order to obtain at least one of the above-mentioned advantages, a piping-type microbial fuel cell is desirable.

[0006] One aspect of the present disclosure is a tubing pipe-type microbial fuel cell, comprising a pipe body through which a liquid flows, one or more anodes provided on the inner surface of the pipe body, and one or more cathodes provided on the inner surface of the pipe body.

[0007] Another aspect of the present disclosure is a piping system comprising a piping structure with a sensor and a controller for controlling a flow of a liquid in the piping structure based on an output of the sensor, the sensor comprising the anode and cathode in the piping pipe microbial fuel cell, and a sensor circuit connected to the anode and the cathode.

[0008] Further details will be described in the following embodiments. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a configuration diagram of a piping system. [Diagram 2] FIG. 2 is a cross-sectional view of a piping-type microbial fuel cell. [Diagram 3] FIG. 3 is an assembly diagram of a piping-type microbial fuel cell. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 5 is a partially cutaway perspective view of a piping-type microbial fuel cell. [Figure 6] FIG. 6 shows the experimental results. [Figure 7] FIG. 7 shows the experimental results. [Figure 8] FIG. 8 shows variations in the arrangement of the anode and cathode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <1. Overview of the piping pipe-type microbial fuel cell and piping system>

[0011] (1) The microbial fuel cell according to the embodiment is a tubing-type microbial fuel cell. The microbial fuel cell may include a pipe body through which a liquid flows, one or more anodes provided on the inner surface of the pipe body, and one or more cathodes provided on the inner surface of the pipe body.

[0012] (2) The cathode preferably has an oxidation-reduction catalytic action and an antibacterial action.

[0013] (3) The cathode preferably has an oxidation-reduction catalyst having an antibacterial effect.

[0014] (4) The cathode preferably contains a cobalt-manganese catalyst.

[0015] (5) The anode is preferably provided on the entire inner surface of the pipe body, and the cathode is preferably provided on the entire inner surface of the pipe body at a position different from that of the anode.

[0016] (6) The cathode is preferably provided downstream of the anode in the pipe body.

[0017] (7) The one or more anodes and the one or more cathodes may be a plurality of anodes and a plurality of cathodes, respectively. The anodes and the cathodes are preferably provided alternately in the direction of liquid flow.

[0018] (8) A piping system according to an embodiment may include a piping structure having a sensor, and a controller that controls the flow of liquid in the piping structure based on the output of the sensor. The sensor may include the anode and cathode in the piping pipe type microbial fuel cell according to any one of (1) to (7) above, and a sensor circuit connected to the anode and the cathode.

[0019] <2. Examples of piping-type microbial fuel cells and piping systems>

[0020] FIG. 1 shows a piping system 50 according to an embodiment. The piping system 50 includes a piping structure 100 and a controller 200. The piping structure 100 is a structure that serves as a flow path, and includes piping pipes and the like. The piping structure 100 is used to pass a liquid that may contain organic matter. The liquid that flows through the piping structure 100 is, for example, waste liquid. The waste liquid may contain organic matter. The liquid contains microorganisms.

[0021] A piping structure 100 shown in FIG. 1 includes a piping pipe type microbial fuel cell 10 in a portion thereof. The piping pipe type microbial fuel cell 10 has a piping pipe shape, and liquid flows inside. The piping pipe type microbial fuel cell 10 generates power by using the liquid inside. In addition, liquid such as waste liquid is purified by microorganisms.

[0022] The piping structure 100 shown in FIG. 1 includes, as an example, a first piping pipe 110, a second piping pipe 120, a valve 130, and a third piping pipe 140 in addition to the microbial fuel cell 10. The first piping pipe 110 is connected to the upstream side of the piping pipe type microbial fuel cell 10. The second piping pipe 120 is connected to the downstream side of the piping pipe type microbial fuel cell 10. The valve 130 is connected to the downstream side of the second piping pipe 120. The third piping pipe 140 is connected to the downstream side of the valve 130. The valve 130 opens and closes the flow path. When the valve 130 is opened, the liquid upstream of the valve 130 flows to the downstream side. When the valve 130 is closed, the flow of the liquid is stopped.

[0023] The opening and closing of the valve 130 is controlled by the controller 200. The controller 200 controls the flow of liquid in the piping structure. The controller 200 can output a control signal for controlling the opening and closing of the valve 130 based on, for example, the output of the microbial fuel cell 10. As an example, the controller 200 can detect that the amount of organic matter in the liquid inside the piping pipe type microbial fuel cell 10 has fallen below a reference value based on the amount of power generated by the piping pipe type microbial fuel cell 10, and when the amount of organic matter in the liquid inside the piping pipe type microbial fuel cell 10 falls below the reference value, control the valve 130 to open and discharge the liquid.

[0024] The valve 130 may be provided on the upstream side of the piping pipe type microbial fuel cell 10, or may be provided on both the upstream side and downstream side of the piping pipe type microbial fuel cell 10.

[0025] The piping pipe type microbial fuel cell 10 includes a pipe body 20. The pipe body 20 may be made of the same material and shape as a normal piping pipe. A liquid flows through the pipe body 20. The pipe body 20 includes a first end 22A connected to another first piping pipe 110 and a second end 22B connected to another second piping pipe 120. The pipe body 20 may be straight or bent, such as L-shaped or U-shaped.

[0026] Here, the pipe generally refers to a structure having a hollow structure for flowing liquid, including a "tube." The material of the pipe body 20 may be a hard material that does not bend, or a soft material that can bend. The flow path diameter of the pipe body 20 is not particularly limited.

[0027] The first end 22A is a connection end that is integrally provided with a joint for connection to the first piping pipe 110 and is connected to the first piping pipe 110 via the joint. Alternatively, the first end 22A does not have an integral joint and is a connection end that is connected to the first piping pipe 110 via a separate joint.

[0028] The second end 22B is a connection end that is integrally provided with a joint for connection to the second piping pipe 120 and is connected to the second piping pipe 120 via the joint. Alternatively, the second end 22B does not have an integral joint and is a connection end that is connected to the second piping pipe 120 via a separate joint.

[0029] The microbial fuel cell 10 includes an anode 30A and a cathode 30B. The anode 30A collects electrons generated by the microorganisms in the liquid decomposing organic matter. Protons (H+) generated at the anode 30A move through the liquid to the cathode 30B. The protons react with the electrons that have moved from the anode 30A to the cathode 30B and with oxygen near the cathode 30B to become water. Therefore, when the microbial fuel cell 10 is used, electricity can be generated using the organic matter in the liquid. Furthermore, the liquid is purified by decomposing the organic matter in the liquid.

[0030] The anode 30A and cathode 30B of the microbial fuel cell 10 of the embodiment can be used, for example, as a sensor element of a sensor that generates a sensor output signal according to the amount of power generation.

[0031] The microbial fuel cell 10 includes a load 40 connected to the anode 30A and the cathode 30B. The load 40 consumes the generated power. The load 40 is, for example, a sensor circuit 40. The sensor circuit 40 outputs a sensor output signal corresponding to the amount of power generated. Since the amount of power generated by the microorganism increases as the amount of organic matter in the liquid increases, the sensor output signal can be a signal corresponding to the amount of organic matter in the liquid inside the pipe-type microbial fuel cell 10. The sensor circuit 40 can have a communication circuit that transmits the sensor output signal to the controller 200 by wired communication or wireless communication.

[0032] 2 to 5 show an example of the structure of a pipe-type microbial fuel cell 10. The illustrated pipe-type microbial fuel cell 10 includes a pipe body 20 and an electrode device 30 provided in the pipe body 20. The pipe body 20 is cylindrical, for example. The electrode device 30 includes a support 31 for the electrodes 30A and 30B, and an anode 30A and a cathode 30B supported by the support 31. That is, the anode 30A and the cathode 30B are provided along the inner surface of the pipe body 20 via the support 31. By providing the anode 30A and the cathode 30B along the inner surface of the pipe body 20, the anode 30A and the cathode 30B do not interfere with the flow of the liquid. In addition, by providing the anode 30A and the cathode 30B along the inner surface of the pipe body 20, it is easy to increase the area in which the anode 30A and the cathode 30B come into contact with the liquid.

[0033] The support 31 has a shape that allows it to be attached to the inner surface of the pipe body 20. For example, when the pipe body 20 is cylindrical, the support 31 is also cylindrical and is fitted inside the pipe body 20 so that its outer circumferential surface contacts the inner circumferential surface. As shown in Fig. 2, the electrode device 30 is inserted into the pipe body 20 from the first end 22A (or the second end 22B) of the pipe body 20 and attached to the pipe body 20. The inner circumferential surface of the pipe body 20 and the outer circumferential surface of the support 31 are bonded together by, for example, an adhesive.

[0034] The electrode device 30 may be attached to the pipe body 20 so as to be detachable from the pipe body 20. In this case, it becomes possible to replace the electrode device 30. Since the anode 30A and the cathode 30B are configured as an integral structure by the support 31, the anode 30A and the cathode 30B can be easily removed from the pipe body 20 by removing the entire electrode device 30 from the pipe body 20.

[0035] The support 31 may be composed of an anode support that supports the anode 30A and a cathode support that supports the cathode 30B. The anode support and the cathode support may be configured as separate bodies. In this case, the anode 30A and the cathode 30B can be replaced separately.

[0036] The support 31 is cylindrical with both ends 33A and 33B open, and has an internal space 32. The liquid flowing in from the first end 22A of the pipe body 20 flows through the opening of the first end 33A of the support, in the internal space 32 of the support 31, and flows out through the second end 33B of the support and the second end 22B of the pipe body. The inner diameter (flow path diameter) of the support 31 is preferably the same as or larger than the inner diameters of the other piping pipes 110 and 120. In this case, the electrode device 30 is prevented from blocking the flow of the liquid.

[0037] As shown in Fig. 4, the electrode device 30 is attached to the entire inner circumference of the pipe body 20. The anode 30A is attached to the entire inner circumference of the support 31. Therefore, the anode 30A is provided on the entire inner circumference of the pipe body 20. Similarly, the cathode 30B is provided on the entire inner circumference of the pipe body 20. Since the anode 30A and the cathode 30B are each provided on the entire inner circumference of the pipe body 20, when the piping pipe-type microbial fuel cell 10 is installed, the liquid inside can come into contact with the anode 30A and the cathode 30B regardless of which position in the circumferential direction is on the lower side.

[0038] In addition, since the cathode 30B is provided on the entire inner surface of the pipe body, one of the circumferential positions of the cathode 30B is located on the upper side. The cathode 30B located on the upper side is easily in contact with the air present together with the liquid in the pipe-type microbial fuel cell 10, which is advantageous for supplying oxygen to the cathode 30B. Note that the anode 30A may be provided on one part of the circumferential direction, and the cathode 30B may be provided on the other part of the circumferential direction.

[0039] 2, the anode 30A and the cathode 30B are attached to mounting recesses 31A, 31B formed on the inner surface of the support 31. The mounting recess 31A for the anode 30A is formed on the upstream side of the support 31. The mounting recess 31B for the cathode 30B is formed on the downstream side of the support 31 with a gap between them. The mounting recesses 31A, 31B are annular grooves that run along the entire circumference of the inner surface of the support 31.

[0040] The anode 30A and the cathode 30B are formed in an annular shape so as to be attached to the mounting recesses 31A and 31B, respectively, and liquid flows through their internal spaces 30A-1 and 30B-1. The anode 30A and the cathode 30B are arranged so that their inner surfaces do not have a step with the inner surface of the support 31 in the range where the anode 30A and the cathode 30B are not present. Therefore, the inner diameters of the inner spaces 30A-1 and 30B-1 of the anode 30A and the cathode 30B are almost the same as the inner diameter of the support 31 in the range where the anode 30A and the cathode 30B are not present. By having these inner diameters almost the same, it is possible to prevent the flow of the fluid from being obstructed by the anode 30A and the cathode 30B.

[0041] As shown in the figure, the anode 30A is preferably provided upstream of the cathode 30B. When the anode 30A is located upstream, protons generated at the anode 30A can reach the cathode 30B by the flow of the liquid. Therefore, the flow of the liquid does not hinder the movement of the protons.

[0042] As shown in FIG. 2, the piping pipe type microbial fuel cell 10 includes terminals 41 and 42 extending from the anode 30A and the cathode 30B, respectively. The terminals 41 and 42 electrically connect the anode 30A and the cathode 30B to the load 40. The terminals 41 and 42 extend outward from the pipe body 20 through the insertion holes 34A and 34B provided in the support and the insertion holes 24A and 24B provided in the pipe body 20. Therefore, the anode 30A and the cathode 30B in the pipe body 20 can be connected to the load 40 provided outside the pipe body 20. The insertion holes 24A and 24B are sealed by the seal parts 26A and 26B around the terminals 41 and 42 to prevent the liquid from flowing out of the pipe body 20. The load 40 may be attached integrally to the pipe body 20 or may be provided separately from the pipe body 20.

[0043] The cathode 30B preferably has an oxidation-reduction catalyst for promoting an oxidation-reduction reaction in the cathode 30B. When the cathode 30B has an oxidation-reduction catalyst, the output of the microbial fuel cell 10 is improved. When the cathode 30B has a strong oxidation-reduction effect, it is possible to suppress a decrease in output even in an environment with little oxygen, such as inside a piping pipe. In addition, the cathode 30B preferably has an antibacterial effect (germicidal effect). When the cathode 30B has an antibacterial effect, it is possible to reduce or prevent the attachment of microorganisms (formation of a biofilm) to the cathode 30B. When a biofilm is formed on the cathode 30B, the output decreases, but the output decrease can be suppressed by the cathode antibacterial effect.

[0044] The catalyst contained in the cathode 30B preferably has both an oxidation-reduction action and an antibacterial action. The cathode 30B may contain both a substance that acts as an oxidation-reduction catalyst (e.g., platinum) and a substance that has an antibacterial action (e.g., copper), but it is preferable that the catalyst has not only an oxidation-reduction action but also an antibacterial action.

[0045] The catalyst is preferably a cobalt-manganese catalyst (cobalt-manganese compound). Cobalt-manganese compounds have oxidation-reduction and antibacterial (bactericidal) properties. Cobalt-manganese catalysts are less expensive than platinum and are therefore advantageous. The cobalt-manganese catalyst is, for example, a cobalt-manganese oxide catalyst. The cobalt-manganese oxide catalyst is, for example, a cobalt-manganese dioxide catalyst.

[0046] The catalyst is preferably a Co-δ-MnO2 / C catalyst. Co-δ-MnO2 / C is a mixture of cobalt-manganese dioxide, Co-δ-MnO2, and carbon C. Carbon C also has a catalytic effect. Carbon C also acts as an electrode.

[0047] Co-δ-MnO2 is a birnessite-type MnO2 (δ-MnO2) intercalated with cobalt Co.

[0048] Co-δ-MnO2 / C is prepared, for example, as follows. (1) Add 0.79 g of KMnO4 to 50 ml of deionized water and stir (400 rpm) for 30 minutes. (2) Add 0.1 mol / l Co(NO3) to (1) above. 2 Add 67.8 ml of 6H2O aqueous solution dropwise and stir (400 rpm) at 70°C for 1 hour. (3) Add 0.5 g of carbon black to (2) above and stir (400 rpm) until the solution changes from purple to black. (4) The product is removed by centrifugation. (5) Dry at 60°C.

[0049] The following describes an example of a method for producing the anode 30A and the cathode 30B in the microbial fuel cell 10. The anode 30A and the cathode 30B can be constructed by applying an electrode material to a urethane foam sheet (see FIG. 2) as the base material 300 and drying it. Urethane foam allows liquid to enter and has a porous three-dimensional structure, which allows the electrode surface area to be large.

[0050] The electrode materials for the anode 30A were 2g of carbon fiber (CF), 2g of activated carbon particles (ACP), and 10ml of carbon nanotube (CNT) dispersion. These electrode materials were mixed for 20 minutes, and the resulting mixture was applied to a 5mm-thick urethane foam sheet to coat the urethane foam. It was then dried in a vacuum dryer at 40°C for 24 hours. The anode 30A was obtained by the above method.

[0051] The electrode materials for the cathode 30B are 1 g of Co-δ-MnO2 / C catalyst and 10 ml of carbon nanotube dispersion liquid. The Co-δ-MnO2 / C catalyst prepared by the above-mentioned preparation method can be used. These electrode materials are mixed for 20 minutes, and the resulting mixture is applied to a 5 mm thick urethane foam sheet to coat the urethane foam. It is then dried in a vacuum dryer at 40°C for 24 hours. By the above method, an anode 30A with a catalyst is obtained.

[0052] <3. Experiment>

[0053] The anode 30A and cathode 30B produced as described above were used to produce a piping-type microbial fuel cell 10 as shown in Figures 2 to 5. A power generation experiment was carried out using the produced piping-type microbial fuel cell 10. In the experiment, 5 ml of muddy water was attached to the anode 30A in order to use bacteria in the soil for power generation.

[0054] Since the experiment was conducted in a laboratory, the piping structure 100 as shown in FIG. 1 was not constructed, and the downstream end 22B of the pipe body 20 was closed with a lid to simulate a closed valve 130. In addition, an L-shaped joint was attached to the upstream end 22A of the pipe body 20. In the experiment, the piping pipe-type microbial fuel cell 10 was installed horizontally, with one opening of the L-shaped joint facing upward. One opening of the L-shaped joint was used as a liquid inlet.

[0055] In the experiment, the LB culture solution was injected into the piping-type microbial fuel cell 10 from one opening of the L-shaped joint. The LB culture solution imitates wastewater having a certain chemical oxygen demand (COD). The LB culture solution is a solution containing 10 g / l glucose, 10 g / l tryptone, 5 g / l yeast extract, 10 g / l sodium chloride, and sodium hydroxide. The sodium hydroxide is used to adjust the pH of the LD culture solution to 7.0. The prepared LD culture solution was sterilized using an autoclave.

[0056] This LB culture solution was added to purified water to prepare concentrations of 1%, 2%, 3%, 4%, and 5%. The LB culture solution with a concentration of 1% corresponds to a chemical oxygen demand (COD) of 200 mg / l, the LB culture solution with a concentration of 2% corresponds to a chemical oxygen demand (COD) of 300 mg / l, the LB culture solution with a concentration of 3% corresponds to a chemical oxygen demand (COD) of 300 mg / l, the LB culture solution with a concentration of 4% corresponds to a chemical oxygen demand (COD) of 800 mg / l, and the LB culture solution with a concentration of 5% corresponds to a chemical oxygen demand (COD) of 1000 mg / l.

[0057] In the experiment, in order to reproduce the environment with the lowest oxygen content, the inside of the piping pipe type microbial fuel cell 10 was filled entirely with LB culture solution so that there were no air pockets inside the piping pipe type microbial fuel cell 10. Specifically, the LB culture solution was injected into the piping pipe type microbial fuel cell 10 from one of the upward openings of the L-shaped joint until the LB culture solution overflowed from that opening.

[0058] A 10 kΩ resistor was connected as the load 40 to the terminals 41 and 42, and the voltage across the load (the voltage generated by the microbial fuel cell 10) was measured. The temperature during the experiment was 25°C to 26°C.

[0059] Figures 6 and 7 show the results of the experiment. Figure 6 shows the change in the generated voltage of the microbial fuel cell 10. In Figure 6, the horizontal axis is time (days) and the vertical axis is voltage. In the experiment, on the first day (day 0), the piping pipe-type microbial fuel cell 10 was filled with 5% LB culture solution equivalent to a COD of 1000 mg / l and left to stand. As shown in Figure 6, the amount of power generated gradually increases up to the fifth day. This is thought to be due to an increase in the number of microorganisms.

[0060] On the fifth day, 2% LB culture solution with a COD equivalent to 400 mg / l was added from one of the upward openings of the L-shaped joint. By adding the LB culture solution, the LB culture solution originally in the piping pipe type microbial fuel cell 10 overflowed from the upward opening of the L-shaped joint, so that the LB culture solution in the piping pipe type microbial fuel cell 10 could be replaced with the 2% LB culture solution. The 2% LB culture solution was injected until the LB culture solution in the piping pipe type microbial fuel cell 10 was mostly replaced with the 2% LB culture solution.

[0061] The amount of electricity generated decreased when 2% LB culture solution was added on the fifth day. The decrease in the amount of electricity generated continued gradually thereafter. Therefore, it was confirmed that the decrease in the amount of electricity generated was caused by the decrease in the COD.

[0062] On the 10th day, 2% LB culture solution with a COD equivalent to 400 mg / l was injected again. The 2% LB culture solution was injected again until the LB culture solution in the piping-pipe-type microbial fuel cell 10 was mostly replaced with the 2% LB culture solution injected again.

[0063] The amount of electricity generated further decreased when 2% LB culture medium was added on the 10th day. This decrease in the amount of electricity generated is thought to be due to the decrease in the number of microorganisms caused by the replacement of the LB culture medium. The decrease in the amount of electricity generated continued gradually thereafter.

[0064] On the 17th day, a 3% LB culture solution with a COD equivalent to 600 mg / l was injected. The 3% LB culture solution was injected until the LB culture solution in the piping-pipe-type microbial fuel cell 10 was mostly replaced with the 3% LB culture solution.

[0065] The amount of electricity generated increased when 3% LB culture solution was added. Therefore, it was confirmed that the amount of electricity generated increases with increasing COD.

[0066] On the 20th day, a 4% LB culture solution with a COD equivalent to 800 mg / l was injected. The 4% LB culture solution was injected until the LB culture solution in the piping-type microbial fuel cell 10 was mostly replaced with the 4% LB culture solution being injected.

[0067] The amount of electricity generated increased when 4% LB culture solution was added. Therefore, it was confirmed that the amount of electricity generated increases with increasing COD.

[0068] On the 24th day, a 5% LB culture solution with a COD equivalent to 1000 mg / l was injected. The 5% LB culture solution was injected until the LB culture solution in the piping-type microbial fuel cell 10 was mostly replaced with the 6% LB culture solution.

[0069] The amount of electricity generated increased when 6% LB culture solution was added. Therefore, it was confirmed that the amount of electricity generated increases with increasing COD.

[0070] On the 31st day, tap water with a COD equivalent to 5 mg / l was injected until the LB culture solution in the piping-type microbial fuel cell 10 was mostly replaced with the injected tap water.

[0071] The amount of electricity generated decreased when tap water was injected. Therefore, it was confirmed that the amount of electricity generated decreased due to the decrease in COD.

[0072] On the 33rd day, 1% LB culture solution with a COD equivalent to 200 mg / l was injected. The 1% LB culture solution was injected until the tap water in the piping-type microbial fuel cell 10 was mostly replaced with the 1% LB culture solution.

[0073] The amount of electricity generated increased when 1% LB culture solution was added. Therefore, it was confirmed that the amount of electricity generated increases with increasing COD.

[0074] A 2% LB culture solution with a COD equivalent to 400 mg / l was injected into the 334. The 2% LB culture solution was injected until the LB culture solution in the piping pipe-type microbial fuel cell 10 was almost replaced with the 2% LB culture solution.

[0075] The amount of electricity generated increased when 2% LB culture solution was added. Therefore, it was confirmed that the amount of electricity generated increases with increasing COD.

[0076] FIG. 7 shows the generated power (P) and power density (PD) of the microbial fuel cell 10. In FIG. 7(A), the horizontal axis shows current, and the vertical axis shows power. In FIG. 7(B), the horizontal axis shows current density, and the vertical axis shows power density. Power density is power divided by the area of ​​the anode. It can be seen that the microbial fuel cell 10 used in the experiment has the power generation characteristics shown in FIG. 7. Therefore, the microbial fuel cell 10 can extract electrical energy from waste liquid.

[0077] As described above, it was confirmed that the presence of liquid containing organic matter in the piping pipe type microbial fuel cell 10 allows power generation. In the experiment, the piping pipe type microbial fuel cell 10 was filled with liquid to prevent the presence of air, but power generation was successful using the oxygen contained in the liquid. It is better for the cathode 30B to be in contact with air in order to obtain oxygen, but it was confirmed that the cathode 30B has a catalyst with a strong oxygen reduction effect, which allows power generation using the oxygen in the liquid. In addition, it was confirmed that the catalyst of the cathode 30B also has an antibacterial effect, which prevents the formation of a biofilm and enables long-term power generation.

[0078] In the experiment, the piping pipe type microbial fuel cell 10 was filled with liquid to simulate an environment with the lowest oxygen content, but in an actual usage environment, air may be present inside the piping pipe type microbial fuel cell 10. When air is present, power can be generated more efficiently. An injection device may be provided to inject air into the liquid inside the piping pipe type microbial fuel cell 10 or into the piping pipe 110 upstream of the piping pipe type microbial fuel cell 10. Power can be generated efficiently by actively injecting air.

[0079] Furthermore, in the experiment, it was confirmed that the amount of electricity generated increases or decreases depending on the increase or decrease in the COD of the liquid in the piping-type microbial fuel cell 10. Therefore, the piping-type microbial fuel cell 10 can be used as a sensor.

[0080] <4. Electrode arrangement example>

[0081] Each of Figures 8(A), (B), and (C) shows variations in the arrangement of the anodes 30A and cathodes 30B in a piping-pipe type microbial fuel cell 10. In a first example shown in Figure 8(A), the anodes 30A and the cathodes 30B are arranged alternately in the direction of liquid flow. The multiple anodes 30A are connected in parallel to the load 40. The multiple cathodes 30B are also connected in parallel to the load 40. By arranging the multiple anodes 30A and cathodes 30B alternately, power can be generated by utilizing a wide range of the liquid flow direction.

[0082] 8(B), a plurality of cathodes 30B connected in parallel are disposed downstream of a plurality of anodes 30A connected in parallel. According to the second example, a wide area on the upstream side can be used as the area of ​​the anodes 30A, and a wide area on the downstream side can be used as the area of ​​the cathodes 30B.

[0083] In the third example shown in Fig. 8(C), similarly to the first example, the anodes 30A and the cathodes 30B are alternately arranged in the direction of liquid flow. In the third example, a first pair of the anodes 30A and the cathodes 30B is connected to a first load 40A, a second pair of the anodes 30A and the cathodes 30B is connected to a second load 40B, and a third pair of the anodes 30A and the cathodes 30B is connected to a third load 40C. In this case, power can be supplied to a plurality of loads 40A, 40B, and 40C.

[0084] The present invention is not limited to the above-described embodiment, and various modifications are possible. [Explanation of symbols]

[0085] 10: Pipe-type microbial fuel cell 20: Pipe body 22A: 1st end 22B: 2nd end 24A: Through hole 24B: Through hole 26A: Seal part 26B: Seal part 30: Electrode device 30A: Anode 30A-1: Internal space 30B: Cathode 30B-1: Internal space 31:Support 31A: Mounting recess 31B: Mounting recess 32: Interior space 33A: Support first end 33B: Support second end 34A: Through hole 34B: Through hole 40: Load 40A: First load 40B: 2nd load 40C: 3rd load 41: Terminal 42: Terminal 50: Piping system 100: Piping structure 110: First piping pipe 120: Second piping 130: Valve 140: 3rd piping pipe 200: Controller 300: Base material

Claims

1. A plumbing pipe type microbial fuel cell, A pipe body through which liquid flows; One or more anodes provided on the inner surface of the pipe body; One or more cathodes provided on the inner surface of the pipe body; Equipped with A plumbing pipe-type microbial fuel cell.

2. The cathode has an oxidation-reduction catalytic action and an antibacterial action. The plumbing pipe type microbial fuel cell according to claim 1.

3. The cathode has an antibacterial redox catalyst. The plumbing pipe type microbial fuel cell according to claim 1.

4. The cathode has a cobalt-manganese based catalyst; The plumbing pipe type microbial fuel cell according to claim 1.

5. The anode is provided on the entire inner surface of the pipe body, The cathode is provided around the entire inner surface of the pipe body at a position different from that of the anode. The plumbing pipe type microbial fuel cell according to claim 1.

6. The cathode is provided downstream of the anode in the pipe body. The plumbing pipe type microbial fuel cell according to claim 1.

7. the one or more anodes and the one or more cathodes are a plurality of anodes and a plurality of cathodes, respectively; The anodes and the cathodes are arranged alternately in the direction of liquid flow. The plumbing pipe type microbial fuel cell according to claim 1.

8. A piping structure including a sensor; a controller for controlling a flow of liquid in the piping structure based on an output of the sensor; Equipped with The sensor comprises the anode and the cathode in the pipe-type microbial fuel cell according to any one of claims 1 to 7, and a sensor circuit connected to the anode and the cathode. Piping system.

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