A microbial fuel cell reactor device for an anaerobic / aerobic membrane bioreactor

Abstract

This invention discloses a microbial fuel cell reactor device resembling an anaerobic / aerobic membrane bioreactor. The device includes an influent system, an effluent system, a main body of the microbial fuel cell reactor, and an energy data acquisition system. The main body of the microbial fuel cell reactor internally comprises an anaerobic anode reaction chamber, an intermediate baffle zone, and an aerobic cathode reaction chamber. The anaerobic anode reaction chamber operates in a plug-flow mode and contains anaerobic sludge and carbon brushes. The intermediate baffle zone isolates the anaerobic anode reaction chamber from the aerobic cathode reaction chamber via left and right plates, respectively, and uses pebbles at the bottom to replace the function of the semi-permeable membrane in traditional microbial fuel cells. The aerobic cathode reaction chamber employs a suspended-rotating biocathode and incorporates a hollow fiber membrane module, operating in a completely mixed mode. This invention has the advantages of low cost, simple and easily scalable structure, strong long-term operational stability, high power generation efficiency, and strong wastewater treatment capacity.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and relates to a device that can efficiently treat wastewater while recovering bioelectricity from the wastewater. Background Technology

[0002] A typical microbial fuel cell consists of an anode chamber and a cathode chamber, usually separated by a membrane that allows proton exchange. Microorganisms in the anode chamber decompose organic matter through anaerobic respiration, producing protons and electrons. Protons pass through the semi-permeable membrane into the cathode chamber, while electrons flow through an external circuit to the cathode electrode, where electron acceptors are reduced. The movement of electrons in the external wires generates electricity. Microbial fuel cells have broad application potential in wastewater treatment, generating clean and renewable bioelectricity while purifying wastewater. Furthermore, compared to traditional activated sludge biological treatment technologies, microbial fuel cells produce less sludge and have lower greenhouse gas emissions, perfectly aligning with the current sustainable and energy-saving development needs in the water treatment field. However, the commercial application of microbial fuel cells is still limited by several factors. First, the investment cost is high; the cost of components such as anode and cathode materials and proton exchange membranes is high, especially when scaled up. Second, in wastewater treatment, the long-term stability and lifespan of microbial fuel cells are still not ideal; how to maintain their long-term effective operation is an urgent problem to be solved. In addition, the current density of most microbial fuel cells remains low, necessitating improvements in the efficiency of microbial electrochemical reactions and electron conduction within the cell. Finally, due to limitations in system design, such as electrode layout and reactor structure, scaling up microbial fuel cells is quite difficult. Summary of the Invention

[0003] This invention addresses the shortcomings of microbial fuel cells, such as high construction costs, difficulty in scaling up, poor long-term operational stability, and the need to improve wastewater treatment performance. It provides a microbial fuel cell reaction device that is low-cost, simple in structure and easy to scale up, has strong long-term operational stability, high power generation efficiency, and strong wastewater treatment capacity, similar to an anaerobic / aerobic membrane bioreactor.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A microbial fuel cell reactor for an anaerobic / aerobic membrane bioreactor includes an influent system, an effluent system, a main body of the microbial fuel cell reactor, and an electrical data acquisition system, wherein:

[0006] The main body of the microbial fuel cell reactor is sequentially provided with an anode anaerobic reaction chamber, an intermediate baffle zone, and a cathode aerobic reaction chamber.

[0007] The anaerobic reaction chamber for the anode is equipped with anaerobic sludge and carbon brushes.

[0008] The intermediate baffle zone is separated from the anode anaerobic reaction chamber and the cathode aerobic reaction chamber by the left and right plates, respectively, and the bottom of the intermediate baffle zone is filled with pebbles.

[0009] The aerobic reaction chamber at the cathode is equipped with aerobic sludge, a mechanical stirrer, a conductive slip ring, a titanium metal brush, a carbon felt block, a hollow fiber membrane module, an aeration pump, an aeration pipe, and an aeration stone. The upper end of the titanium metal brush is connected to the mechanical stirrer and rotates with it, and is connected to an external circuit through the conductive slip ring. The lower end of the titanium metal brush is in intermittent contact with the carbon felt block. A hollow fiber membrane module is installed on the side of the aerobic reaction chamber at the cathode away from the anaerobic reaction chamber at the anode. The aeration stone is located directly below the hollow fiber membrane module and is connected to the aeration pump through an aeration pipe.

[0010] The water inlet system includes a water inlet tank, a water inlet pump, and a water inlet pipe. The water inlet tank is located on one side of the anode anaerobic reaction chamber. Wastewater in the water inlet tank is drawn by the water inlet pump and flows into the anode anaerobic reaction chamber through the water inlet pipe.

[0011] The water outlet system includes an outlet tank, an outlet pump, and an outlet pipe. The outlet tank is located on one side of the cathodic aerobic reaction chamber. The treated water drawn from the hollow fiber membrane module in the cathodic aerobic reaction chamber by the outlet pump flows into the outlet tank through the outlet pipe.

[0012] The power data acquisition system includes wires, a resistor box, a data acquisition unit, and a computer. The carbon brush is connected to the negative terminal of the resistor box via wires, and the conductive slip ring is connected to the positive terminal of the resistor box via wires. At the same time, the positive and negative terminals of the resistor box are connected to the positive and negative terminals of the data acquisition unit. The data acquisition unit captures the voltage information generated at both ends of the resistor box and transmits it to the computer for recording and storage.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1. The reaction device designed in this invention has low cost. It replaces the expensive proton exchange membrane with a baffled region filled with a small amount of pebbles, and uses a biocathode, utilizing microorganisms to catalyze the cathodic reduction reaction. This eliminates the need for expensive metal catalysts or special cathode electrode materials, and also eliminates the need for periodic replacement of the cathode electrolyte. Furthermore, the aerobic reaction chamber of the cathode in this invention uses environmentally friendly and relatively inexpensive carbon felt, as well as titanium metal brushes that do not suffer wear and tear during use. These design features reduce both construction and operating costs.

[0015] 2. The reaction device designed in this invention has high wastewater treatment performance. Wastewater enters the anode anaerobic reaction chamber, is treated by anaerobic sludge, and then flows through the intermediate baffle zone directly into the cathode aerobic reaction chamber for further treatment by aerobic sludge. This achieves two-stage anaerobic-aerobic treatment, efficiently removing pollutants such as organic matter and ammonia nitrogen from the wastewater. Furthermore, the special arrangement of carbon brushes in the anode anaerobic reaction chamber optimizes the water flow direction in the anode anaerobic zone, helping the feed to fully contact the carbon brushes, thereby improving the degradation of anode pollutants and the efficiency of power generation. The introduction of an ultrafiltration membrane module in the cathode aerobic chamber eliminates the need for a secondary sedimentation tank, prevents the loss of suspended carbon felt with the sludge, and further improves the effluent quality.

[0016] 3. The reaction device designed in this invention has a simple structure and is easily scalable. The overall structure of the novel microbial fuel cell reactor designed in this invention is similar to that of an anaerobic / aerobic membrane bioreactor. It does not have a complex structure that is difficult to scale up or would lead to a sharp increase in cost after scaling up. Furthermore, anaerobic / aerobic membrane bioreactors are a mature technology that has been practically applied in the field of wastewater treatment. Therefore, the microbial fuel cell reactor designed in this invention, which resembles an anaerobic / aerobic membrane bioreactor, has the potential to be built into a medium-to-large-scale integrated system.

[0017] 4. The suspended-rotating biocathode designed in this invention enhances the power generation efficiency and stability of the microbial fuel cell, improves its wastewater treatment effect, and helps alleviate membrane fouling. The movement of sludge and suspended carbon felt blocks with the rotating titanium brush enhances the transfer of organic matter and oxygen between the microorganisms and the carbon felt block surface in the aerobic reaction chamber of the cathode. This improves the cathode reduction reaction rate and the device's power generation efficiency, maintains the long-term stability of the cathode potential and the device's power generation, reduces aeration requirements, and the movement of sludge and suspended carbon felt blocks can hinder the formation of filter cake layer on the membrane surface through hydraulic shearing, reducing membrane fouling. Furthermore, because the carbon felt blocks and sludge are fully mixed, and microorganisms adhere to the carbon felt surface, direct interspecies electron transfer is promoted, increasing microbial activity and accelerating pollutant degradation. Attached Figure Description

[0018] Figure 1 A front view of a microbial fuel cell reactor that is a type of anaerobic / aerobic membrane bioreactor;

[0019] Figure 2 A top view of the main body of a microbial fuel cell reactor, which is a type of anaerobic / aerobic membrane bioreactor;

[0020] Figure 3 A perspective view of the water flow path in the intermediate deflection zone;

[0021] Figure 4 A 3D view of a titanium metal brush;

[0022] Figure 5 A top view of a titanium brush;

[0023] In the diagram: 1-Anodic anaerobic reaction chamber, 2-Intermediate baffle zone, 3-Cathode aerobic reaction chamber, 4-Inlet tank, 5-Inlet pipe, 6-Inlet pump, 7-Outlet pipe, 8-Outlet pump, 9-Outlet tank, 10-Carbon brush, 11-Pebble, 12-Titanium brush, 13-Carbon felt block, 14-Hollow fiber membrane module, 15-Aeration pump, 16-Aeration pipe, 17-Aeration stone, 18-Mechanical agitator, 19-Conductive slip ring, 20-Wire, 21-Resistor box, 22-Data acquisition unit, 23-Computer. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0025] This invention provides a microbial fuel cell reactor device similar to an anaerobic / aerobic membrane bioreactor, such as... Figure 1 and Figure 2 As shown, the device includes an inlet water system, an outlet water system, a main body of a microbial fuel cell reactor, and an electrical energy data acquisition system, wherein:

[0026] The water inlet system consists of a water inlet tank 4, a water inlet pump 6, and a water inlet pipe 5.

[0027] The water outlet system consists of a water outlet tank 9, a water outlet pump 8, and a water outlet pipe 7.

[0028] The microbial fuel cell reactor is equipped with an anaerobic anode reaction chamber 1, an intermediate baffle zone 2, and an aerobic cathode reaction chamber 3 arranged sequentially inside the main body.

[0029] The anaerobic reaction chamber 1 of the anode adopts a plug-flow operation mode and is equipped with anaerobic sludge and six carbon brushes 10 arranged in a certain pattern. It remains in a sealed state throughout operation. The carbon brushes 10 serve as the anode electrodes, with every two carbon brushes 10 arranged in adjacent rows, for a total of three rows. The three rows of carbon brushes 10 are arranged as follows: Figure 2 The parallel staggered arrangement shown improves the direction of water flow and promotes full contact between wastewater and carbon brush 10 and anaerobic sludge.

[0030] The intermediate baffle zone 2 isolates the anode anaerobic reaction chamber 1 and the cathode aerobic reaction chamber 3 through left and right plates, respectively. The height of the left plate of the intermediate baffle zone 2 is equal to the total height of the anode anaerobic reaction chamber 1. A rectangular opening is made in the upper part of the left plate to allow water to flow into the intermediate baffle zone 2. The top of the right plate of the intermediate baffle zone 2 is flush with the upper part of the cathode aerobic reaction chamber 3, and the lower part is not connected to the bottom plate of the cathode aerobic reaction chamber 3, allowing water to flow out into the cathode aerobic reaction chamber 3. Furthermore, a small amount of pebbles 11 are filled at the bottom of the intermediate baffle zone 2. The intermediate baffle zone 2 filled with pebbles 11 replaces the function of the semi-permeable membrane in traditional microbial fuel cells. This ensures that the effluent from the anode anaerobic reaction chamber 1 can flow directly into the cathode aerobic reaction chamber 3, while preventing oxygen from the cathode aerobic reaction chamber 3 from entering the anode anaerobic reaction chamber 1 and disrupting its anaerobic environment.

[0031] The aerobic cathode reaction chamber 3 employs a suspended-rotating biological cathode and incorporates a hollow fiber membrane module 14, operating in a completely mixed mode. The aerobic cathode reaction chamber 3 is equipped with aerobic sludge, a mechanical stirrer 18, a conductive slip ring 19, a titanium brush 12, carbon felt blocks 13, the hollow fiber membrane module 14, an aeration pump 15, an aeration pipe 16, and an aeration stone 17. The carbon felt blocks 13 are completely mixed with the aerobic sludge, similar to dispersed biological packing material, and move within the reaction chamber with the rotation of the titanium brush 12. The titanium brush 12 acts as a current collector; its upper end is connected to the stirrer 18 and rotates with it, and it is connected to an external circuit via the conductive slip ring 19. Its lower end is below the liquid surface and intermittently contacts the carbon felt blocks 13 suspended in the water. The titanium brush 12 and the carbon felt blocks 13 together constitute the cathode electrode. Furthermore, a hollow fiber membrane module 14 is installed on the side of the aerobic reaction chamber 3 away from the anaerobic reaction chamber 1, replacing the secondary sedimentation tank. The filtered water extracted from the hollow fiber membrane module 14 serves as the final effluent from the reaction device designed in this invention. The introduction of the hollow fiber membrane module 14 simplifies the device structure, reduces the loss of carbon felt blocks 13 with sludge, and helps improve the effluent quality. In addition, the aeration pump 15 evenly delivers air to the area directly below the hollow fiber membrane module 14 via the aeration pipe 16 and aeration stones 17, providing oxygen to the aerobic reaction chamber 3 while mitigating membrane fouling on the hollow fiber membrane module 14.

[0032] The water inlet system consists of a water inlet tank 4, a water inlet pump 6, and a water inlet pipe 5. The water inlet tank 4 is located on one side of the anode anaerobic reaction chamber 1. The wastewater in the water inlet tank 4 is drawn by the water inlet pump 6 and flows into the anode anaerobic reaction chamber 1 through the water inlet pipe 5.

[0033] The water outlet system consists of an outlet tank 9, an outlet pump 8, and an outlet pipe 7. The outlet tank 9 is located on one side of the cathode aerobic reaction chamber 3. The treated water pumped by the outlet pump 8 from the hollow fiber membrane module 14 in the cathode aerobic reaction chamber flows into the outlet tank 9 through the outlet pipe 7.

[0034] The power data acquisition system consists of a wire 20, a resistor box 21, a data acquisition device 22, and a computer 23. The carbon brush 10 is connected to the negative terminal of the resistor box 21 via the wire 20, and the conductive slip ring 19 is connected to the positive terminal of the resistor box 21 via the wire 20. At the same time, the positive and negative terminals of the resistor box 21 are connected to the positive and negative terminals of the data acquisition device 22, respectively. The data acquisition device 22 captures the voltage information generated across the resistor box 21 and transmits it to the computer 23 for recording and storage.

[0035] The specific operation process is as follows: Wastewater in the inlet tank 4 flows into the anode anaerobic reaction chamber 1 from the lower right corner of the left side wall through the inlet pump 6 and inlet pipe 5. With the special arrangement of six carbon brushes 10, it travels along a relatively long path ( Figure 2 The wastewater flows towards the intermediate baffle zone 2, where some pollutants are degraded by anaerobic sludge. It then flows through the intermediate baffle zone 2 and the pebbles 11 into the cathode aerobic reaction chamber 3. In the cathode aerobic reaction chamber 3, the remaining pollutants are further degraded by aerobic sludge, and then separated by the hollow fiber membrane module 14, ultimately yielding deeply purified effluent. While the anode anaerobic reaction chamber 1 and the cathode aerobic reaction chamber 2 achieve two-stage wastewater treatment, the anaerobic microorganisms in the anode anaerobic reaction chamber 1 generate electrons from the pollutants. These electrons are transferred from the carbon brush 10 through the wire 20, resistor box 21, conductive slip ring 19, and titanium brush 20 to the carbon felt block 13 in the cathode aerobic reaction chamber 3. Simultaneously, the aerobic microorganisms in the cathode aerobic reaction chamber 3 catalyze the cathode reduction reaction, promoting the reduction of electron acceptors (such as oxygen and nitrates) by accepting electrons from the carbon felt block 13. This creates a potential difference between the anode and cathode, generating a voltage across the resistor box 21. The voltage signal across resistor box 21 is detected by data acquisition device 22 and converted into voltage data, which is then stored on computer 23. Through the above process, the microbial fuel cell reactor of the anaerobic / aerobic membrane bioreactor designed in this invention can ultimately efficiently remove pollutants from wastewater while stably generating bioelectricity.

[0036] In this invention, the titanium metal brush 12 is formed by welding a titanium rod to five titanium plates. The welding angles of the five titanium plates are as follows: the angle between the upper and lower plates is 0°, the angle of the middle plate is 90°, and the angles of the other two plates are successively at a 45° angle to the upper plate. Figure 4 , Figure 5 ).

[0037] In this invention, the carbon felt block 13 is filled at a rate of about 40% in the cathode aerobic reaction chamber 3.

[0038] In this invention, the filling height of the pebbles 11 is approximately one-quarter to one-third of the total height of the intermediate deflection region 2.

[0039] In this invention, the main body of the microbial fuel cell reactor is made of plexiglass, with a length of 300mm, a width of 100mm, and a height of 100mm. After the carbon brush 10, pebble 11, titanium brush 12, carbon felt block 13, hollow membrane module 14, and aeration stone 17 are filled, the effective volume of the reactor is approximately 2.2L.

Claims

1. A microbial fuel cell reactor for an anaerobic / aerobic membrane bioreactor, characterized in that... The device includes an inlet water system, an outlet water system, a main body of a microbial fuel cell reactor, and an electrical energy data acquisition system, wherein: The water inlet system includes a water inlet tank, a water inlet pump, and a water inlet pipe; The water outlet system includes a water outlet tank, a water outlet pump, and a water outlet pipe; The main body of the microbial fuel cell reactor is sequentially provided with an anode anaerobic reaction chamber, an intermediate baffle zone, and a cathode aerobic reaction chamber. The anaerobic reaction chamber for the anode is equipped with anaerobic sludge and carbon brushes. The intermediate baffle zone is separated from the anode anaerobic reaction chamber and the cathode aerobic reaction chamber by the left and right plates, respectively, and the bottom of the intermediate baffle zone is filled with pebbles. The aerobic reaction chamber at the cathode is equipped with aerobic sludge, a mechanical stirrer, a conductive slip ring, a titanium brush, a carbon felt block, a hollow fiber membrane module, an aeration pump, an aeration pipe, and an aeration stone. The upper end of the titanium brush is connected to the mechanical stirrer and rotates with it, and is connected to an external circuit through the conductive slip ring. The lower end of the titanium brush is in intermittent contact with the carbon felt block. A hollow fiber membrane module is installed on the side of the aerobic reaction chamber at the cathode away from the anaerobic reaction chamber at the anode. The aeration stone is located directly below the hollow fiber membrane module and is connected to the aeration pump through an aeration pipe. The inlet tank is located on one side of the anode anaerobic reaction chamber. Wastewater in the inlet tank is drawn by the inlet pump and flows into the anode anaerobic reaction chamber through the inlet pipe. The water outlet tank is located on one side of the cathode aerobic reaction chamber. The treated water pumped from the hollow fiber membrane module in the cathode aerobic reaction chamber flows into the water outlet tank through the water outlet pipe. The power data acquisition system includes wires, a resistor box, a data acquisition unit, and a computer. The carbon brush is connected to the negative terminal of the resistor box via wires, and the conductive slip ring is connected to the positive terminal of the resistor box via wires. At the same time, the positive and negative terminals of the resistor box are connected to the positive and negative terminals of the data acquisition unit. The data acquisition unit captures the voltage information generated at both ends of the resistor box and transmits it to the computer for recording and storage.

2. The microbial fuel cell reactor of the anaerobic / aerobic membrane bioreactor according to claim 1, characterized in that... The number of carbon brushes is 6, with each pair of carbon brushes forming a row, for a total of 3 rows, and the three rows of carbon brushes are arranged in parallel and staggered.

3. The microbial fuel cell reactor of the anaerobic / aerobic membrane bioreactor according to claim 1, characterized in that... The height of the left plate in the intermediate baffle zone is equal to the total height of the anode anaerobic reaction chamber. An opening is made at the top of the left plate to allow water to flow into the intermediate baffle zone.

4. The microbial fuel cell reactor of the anaerobic / aerobic membrane bioreactor according to claim 3, characterized in that... The opening is rectangular in shape.

5. The microbial fuel cell reactor of the anaerobic / aerobic membrane bioreactor according to claim 1, characterized in that... The top of the right plate of the intermediate baffle zone is flush with the upper part of the cathode aerobic reaction chamber, and the lower part is not connected to the bottom plate of the cathode aerobic reaction chamber. The water supply flows out to the cathode aerobic reaction chamber.

6. The microbial fuel cell reactor of the anaerobic / aerobic membrane bioreactor according to claim 1, characterized in that... The titanium metal brush is made of titanium rods welded to five titanium plates. The welding angles of the five titanium plates are as follows: the angle between the upper plate and the lower plate is 0°, the angle of the middle plate is 90°, and the angles of the other two plates are successively at a 45° angle to the upper plate.

7. The microbial fuel cell reactor of the anaerobic / aerobic membrane bioreactor according to claim 1, characterized in that... The carbon felt block was 40% filled in the cathode aerobic reaction chamber.

8. The microbial fuel cell reactor of the anaerobic / aerobic membrane bioreactor according to claim 1, characterized in that... The pebble filling height is one-quarter to one-third of the total height of the intermediate deflection zone.

9. The microbial fuel cell reactor of the anaerobic / aerobic membrane bioreactor according to claim 1, characterized in that... The main body of the microbial fuel cell reactor is made of plexiglass.

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