Artificial wetland microbial fuel cell coupling device based on novel three-dimensional electrode

Abstract

The invention discloses a constructed wetland microbial fuel cell coupling device based on a novel three-dimensional electrode, and belongs to the technical field of sewage treatment, the device comprises a shell, and a bottom layer, an anode layer, a middle layer and a cathode layer are sequentially arranged in the shell from bottom to top. Wherein the bottom layer is filled with coarse gravels, and the middle layer is filled with fine gravels; the anode layer consists of a plurality of titanium tubes which are horizontally arranged and a titanium mesh for connecting the titanium tubes in parallel; openings are formed in the two ends of the titanium tube, through holes are formed in the titanium tube in an array mode, and the titanium tube is filled with a graphite felt core formed in a curled mode. The graphite felt core body can be used for a conductive material strengthening process and can also be used as a supporting material, and compared with an anode cage structure formed by a stainless steel net, the bearing strength is higher; the resistance of the metallic titanium is lower than that of the stainless steel mesh, so that electron transmission and improvement of electron transfer efficiency are facilitated, and the energy recovery efficiency and pollutant removal efficiency of the constructed wetland microbial fuel cell coupling device can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to an artificial wetland microbial fuel cell coupling device based on a novel three-dimensional electrode. Background Art

[0002] Constructed wetlands (CW) are a water treatment ecosystem that artificially combines functional matrices such as sand, stone, and soil in a specific proportion, and selectively implants wetland plants into them. Constructed wetlands remove pollutants from wastewater through natural processes such as matrix adsorption, plant absorption, and microbial degradation under the joint action of wetland matrices, plants, and microorganisms. Compared with traditional water treatment methods, constructed wetlands have the advantages of low operating costs, durability, low external energy requirements, and simple operation, making them very suitable for sewage treatment in medium and small towns.

[0003] Microbial fuel cells (MFCs) are the product of the combination of microorganisms and bioelectric current technology. They can use microorganisms as catalysts to purify wastewater while harvesting electricity. They are currently a widely-watched bioelectrochemical clean energy technology. Microbial fuel cell electricity generation is currently the most studied application of microbial electrochemical technology. Microorganisms use the anode as an electron acceptor to oxidize organic compounds. The electrons reach the cathode through an external circuit to reduce oxygen, completing the process of electricity generation.

[0004] The constructed wetland-microbial fuel cell (CW-MFC) system, which is a coupling between an artificial wetland and a microbial fuel cell, is a new type of sewage treatment process based on a bio-electrochemical technology. The upper part of the artificial wetland is an aerobic environment, the lower part is an anaerobic environment, and there is a significant redox potential gradient at different heights inside. The artificial wetland can provide the required redox gradient for the microbial fuel cell, and the root secretions of plants in the artificial wetland can provide chemical energy for the microbial fuel cell. The introduction of the microbial fuel cell forms a closed loop, and the electric current can enhance the activity of the microorganisms, thereby having a more efficient pollutant removal efficiency.

[0005] The anode layer in the CW-MFC system is not only a carrier for microorganisms to attach, but also one of the main places for anaerobic reactions to degrade pollutants. The existing anode layer generally uses an anode cage made of stainless steel mesh, which can accommodate more microorganisms to grow. These microorganisms loaded on the electrode have a shorter electron transfer path than those suspended in the solution. However, this anode cage structure is difficult to carry the heavier filler in the CW-MFC system, and it is very easy to compact and cause the anode layer to be blocked, eventually causing the anode layer to fail and causing the system to be unable to operate. In addition, the loaded microorganisms are easy to stack. Since the microbial cell membrane is not conductive, the multi-layer stacked biological cells are not conducive to improving the electron transfer efficiency.

[0006] Therefore, developing high-performance anode layer electrode materials is one of the main strategies to improve the energy recovery efficiency and pollutant removal efficiency of CW-MFC systems. Summary of the invention

[0007] The purpose of the present invention is to provide a contrived wetland microbial fuel cell coupling device based on a novel three-dimensional electrode, wherein a novel three-dimensional electrode composed of a plurality of titanium tubes is adopted in the anode layer, and the titanium tubes are filled with a curled graphite felt core; the three-dimensional electrode has a large specific surface area, good electrical conductivity and high biocompatibility, can achieve a higher bioload capacity, and effectively improve the energy recovery efficiency and pollutant removal efficiency of the contrived wetland-microbial fuel cell system.

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

[0009] A novel three-dimensional electrode-based artificial wetland microbial fuel cell coupling device includes a shell, wherein a bottom layer, an anode layer, an intermediate layer and a cathode layer are sequentially arranged inside the shell from bottom to top. The bottom layer is filled with coarse gravel, and the intermediate layer is filled with fine gravel.

[0010] Furthermore, the shell is a cylindrical container with an open top, and the ratio of the height to the diameter of the shell is 13:4.

[0011] Further, the diameter of the coarse gravel is 20-75 mm, and the diameter of the fine gravel is 1-2 mm.

[0012] Furthermore, the anode layer is composed of a plurality of horizontally arranged titanium tubes and a titanium mesh for connecting the titanium tubes in parallel. The two ends of the titanium tubes are provided with openings, the titanium tubes are provided with through holes in an array, and the inside of the titanium tubes is filled with a curled graphite felt core.

[0013] Furthermore, the cathode layer is composed of graphite felt and titanium wire inserted into the graphite felt, the graphite felt is wrapped by a net bag, and the titanium wire of the cathode layer is electrically connected to a data recorder.

[0014] Furthermore, wetland plants are planted on the upper part of the cathode layer.

[0015] Furthermore, the shell is provided with side water outlet pipes with valves at the bottom layer, anode layer, middle layer and cathode layer, and the water outlet pipes can be used for sampling; a water inlet pipe is provided on the top of the shell, the water inlet pipe passes through the cathode layer and extends into the middle layer, and an array of water diversion holes is opened at the water inlet pipe located in the middle layer.

[0016] Furthermore, the wastewater retention time of the artificial wetland microbial fuel cell coupling device is 1-3 days.

[0017] Beneficial effects of the present invention:

[0018] The artificial wetland microbial fuel cell coupling device based on the novel three-dimensional electrode of the present invention has the advantages of low cost, simple structure, convenient assembly and suitability for mass production, etc. The metal titanium has good biocompatibility and is more environmentally friendly. After being started by pre-cultivation, the artificial wetland microbial fuel cell coupling device can stably remove pollutants in sewage and can output current stably.

[0019] The three-dimensional electrode of the anode layer is composed of multiple horizontally arranged titanium tubes and titanium mesh for parallel connection of the titanium tubes. The through holes on the titanium tubes are conducive to the hydraulic transmission inside the coupling device; the inside of the titanium tubes is filled with a curled graphite felt core, which can be used as a conductive material reinforcement process and as a supporting material. Compared with the anode cage structure composed of stainless steel mesh, it has the characteristics of high pressure bearing strength and not easy to deform, which is conducive to ensuring the stable operation of the coupling device. The resistance of metal titanium (4.2×10 -8 Ω·m) is lower than the resistance of the stainless steel mesh (1.45×10 -6 Ω·m), which is beneficial to electron transmission and improves the overall efficiency of the coupling device.

[0020] The anode layer composed of the graphite felt and the titanium tube of the present invention has a large specific surface area and biocompatibility, which helps to provide more microbial attachment sites, and the curled and stacked graphite felt core helps to reduce the stacking thickness of the microorganisms, thereby further improving the electron transfer efficiency, and can effectively improve the energy recovery efficiency and pollutant removal efficiency of the artificial wetland microbial fuel cell coupling device. Openings are provided at both ends of the titanium tube to facilitate replacement of the filled graphite felt core, avoid blockage and failure problems inside the titanium tube as the microorganisms grow, and facilitate maintenance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below in conjunction with the accompanying drawings.

[0022] Figure 1 It is a schematic diagram of the internal structure of the artificial wetland microbial fuel cell coupling device based on the novel three-dimensional electrode of the present invention;

[0023] Figure 2 It is a schematic structural diagram of the anode layer of the present invention.

[0024] In the figure: 1, shell; 2, bottom layer; 3, anode layer; 31, titanium tube; 32, titanium mesh; 33, graphite felt core; 34, through hole; 4, middle layer; 5, cathode layer; 6, water inlet pipe; 61, water distribution hole; 7, side outlet pipe. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example 1

[0027] A contrived wetland microbial fuel cell coupling device based on a novel three-dimensional electrode, such as Figure 1 As shown, the device comprises a shell 1, inside which a bottom layer 2, an anode layer 3, an intermediate layer 4 and a cathode layer 5 are arranged in sequence from bottom to top.

[0028] The bottom layer 2 is filled with coarse gravel, the middle layer 4 is filled with fine gravel, and the upper part of the cathode layer 5 is planted with wetland plants.

[0029] The shell 1 is a cylindrical container with an opening at the top. The material of the shell 1 includes but is not limited to PVC or organic glass. The ratio of the height to the diameter of the shell 1 is 13:4. The shell 1 is provided with a side outlet pipe 7 with a valve at the bottom layer 2, the anode layer 3, the middle layer 4 and the cathode layer 5. The side outlet pipe 7 can be used for sampling. The top of the shell 1 is provided with a water inlet pipe 6, which passes through the cathode layer 5 and extends into the middle layer 4. The water inlet pipe 6 is located at the middle layer 4 and is provided with a water distribution hole 61 in an array.

[0030] See also Figure 2 The anode layer 3 is a three-dimensional electrode, which is composed of a plurality of horizontally arranged titanium tubes 31 and a titanium mesh 32 for connecting the titanium tubes 31 in parallel. The length of the titanium tube 31 is adjusted according to the space in the shell 1, so that both ends of the titanium tube 31 are close to the inner wall of the shell 1. The titanium tube 31 is provided with through holes 34 in an array, and the inside of the titanium tube 31 is filled with a graphite felt core 33 formed by curling graphite felt.

[0031] The anode layer 3 in the form of a three-dimensional electrode has the characteristics of high strength, large specific surface area, good electrical conductivity, high biocompatibility and large bioloading capacity.

[0032] The cathode layer 5 is composed of graphite felt and titanium wire inserted into the graphite felt. The graphite felt is wrapped by a net bag. The titanium wire of the cathode layer 5 is electrically connected to a data recorder.

[0033] The present embodiment adopts a shell 1 made of PVC material, the height of the shell 1 is 65 cm and the diameter is 20 cm; the titanium tube 31 assembly of the present embodiment includes 3 titanium tubes 31, the diameter of the titanium tube 31 is 5 cm, and the diameter of the through hole 34 on the titanium tube 31 is 5 mm; the diameter of the fine gravel filled in the middle layer 4 is 1-2 mm, and the diameter of the coarse gravel filled in the bottom layer 2 is 20-75 mm.

[0034] The startup method of the device is as follows: the sludge in the concentrated sludge pool of the sewage treatment plant is used, and after sealed cultivation and dilution, various indicators are adjusted to the preset values, and then it can be injected into the artificial wetland microbial fuel cell coupling device through the water inlet pipe 6 as artificial simulated sewage, and the voltage is recorded by a data recorder connected to the cathode layer 5 by telecommunications, and water samples are collected through the side outlet pipe 7 every 1-3 days to monitor various indicators in the water samples. This process is the pre-cultivation stage, and the ability to remove pollutants in sewage is unstable. When the output voltage of the artificial wetland microbial fuel cell coupling device is stable, it means that the sludge has been domesticated, and the device can be regarded as successfully started.

[0035] The preset values ​​of various indicators of artificial simulated wastewater are shown in Table 1:

[0036] Table 1

[0037] project COD Total Nitrogen Ammonia nitrogen Nitrate Total Phosphorus Concentration mg / L 200 30 25 5 2.5

[0038] After the output voltage is stabilized, the artificial wetland microbial fuel cell coupling device can stably output electrical energy and can stably remove pollutants in sewage.

[0039] It should be noted that, in this article, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0040] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A contrived wetland microbial fuel cell coupling device based on a novel three-dimensional electrode, characterized in that: It comprises a shell (1), wherein a bottom layer (2), an anode layer (3), an intermediate layer (4) and a cathode layer (5) are arranged in sequence from bottom to top inside the shell (1); the bottom layer (2) is filled with coarse gravel, and the intermediate layer (4) is filled with fine gravel; The anode layer (3) is composed of a plurality of titanium tubes (31) arranged horizontally and a titanium mesh (32) for connecting the titanium tubes (31) in parallel; openings are provided at both ends of the titanium tubes (31); through holes (34) are provided in an array on the titanium tubes (31); and a curled graphite felt core (33) is filled inside the titanium tubes (31).

2. According to claim 1, a novel three-dimensional electrode-based artificial wetland microbial fuel cell coupling device is characterized in that: The shell (1) is a cylindrical container with an open top, and the ratio of the height to the diameter of the shell (1) is 13:

4.

3. According to claim 1, a novel three-dimensional electrode-based artificial wetland microbial fuel cell coupling device is characterized in that: The diameter of the coarse gravel is 20-75 mm, and the diameter of the fine gravel is 1-2 mm.

4. According to claim 1, a novel three-dimensional electrode-based artificial wetland microbial fuel cell coupling device is characterized in that: The cathode layer (5) is composed of graphite felt and titanium wires inserted into the graphite felt, and the graphite felt is wrapped by a net bag.

5. The artificial wetland microbial fuel cell coupling device based on a novel three-dimensional electrode according to claim 4 is characterized in that: The titanium wire is electrically connected to a data logger for recording the voltage.

6. The artificial wetland microbial fuel cell coupling device based on a novel three-dimensional electrode according to claim 1 is characterized in that: The shell (1) is provided with side water outlet pipes (7) with valves at the bottom layer (2), the anode layer (3), the middle layer (4) and the cathode layer (5); the top of the shell (1) is provided with a water inlet pipe (6) that passes through the cathode layer (5) and extends into the middle layer (4); and the water inlet pipe (6) is provided with water distribution holes (61) in an array at the position of the middle layer (4).

7. The artificial wetland microbial fuel cell coupling device based on a novel three-dimensional electrode according to claim 1 is characterized in that: Wetland plants are planted on the upper part of the cathode layer (5).

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