Aerobic biological cathode for concentration of nutrient solution

Abstract

The aerobic biological cathode comprises a cation exchange membrane and an anion exchange membrane which are rolled into a cylinder shape, the cation exchange membrane is arranged on the inner side of the anion exchange membrane, an upper joint is formed at the top of the cation exchange membrane and the top of the anion exchange membrane, and a lower joint is formed at the bottom of the anion exchange membrane. A lower joint is formed at the bottoms of the cation exchange membrane and the anion exchange membrane to form a concentration membrane roll, and a space is reserved between the cation exchange membrane and the anion exchange membrane to form a concentration chamber. The top of the concentration chamber is connected with an upper water pipe leading to the outside, and the bottom is connected with a lower water pipe leading to the outside. The aerobic biological cathode further comprises a cylindrical carbon felt surrounding and wrapping the concentration film roll, and further comprises an aeration pipe surrounding and wrapping the bottom of the carbon felt, a plurality of aeration holes are formed in the pipe wall of the aeration pipe, and an air inlet pipe is further connected to the aeration pipe. The internal resistance of the system is reduced by improving the microbial activity of the cathode through aeration optimization, so that the comprehensive performance of a concentrated and extracted nutrient solution can be improved in wastewater treatment.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, specifically to an aerobic biological cathode for nutrient solution concentration. Background Technology

[0002] Wastewater, such as domestic sewage and brewing wastewater, is rich in nutrients like nitrogen and phosphorus, which are essential for plants and microorganisms. It can be widely used in agriculture, horticulture, and aquaculture. By treating biological wastewater and removing harmful substances, it can be transformed into various highly efficient nutrient solutions, making it an effective means of wastewater resource utilization. Among these methods, using microbial electro-desalination technology to concentrate and extract biological wastewater is a promising and innovative technique.

[0003] Microbial electro-desalination technology integrates the principles of microbial fuel cells and electrodialysis. Electron-producing microorganisms in the anode oxidize and decompose organic matter, generating electrons and chloride ions. Electrons are transferred to the cathode via an external circuit, while hydrogen ions travel from the anode chamber through multiple ion exchange membranes to the cathode chamber, where they react with oxygen to produce water, thus forming a current loop. The bioelectric energy generated by microbial metabolism drives ion migration in wastewater, achieving multiple functions such as wastewater treatment, brine desalination, and nutrient solution recovery. It is an energy-saving, economical, and environmentally sustainable technology. However, in existing microbial electro-desalination technologies, the aerobic biocathode is affected by dissolved oxygen concentration, mass transfer efficiency, and microbial activity, resulting in significant fluctuations in cathode potential. This leads to poor and unstable system performance, making it difficult to effectively implement microbial electro-desalination technology in the concentration and extraction of nutrient solutions from biological wastewater.

[0004] The inventors discovered through research that the high internal resistance of the cathode is a key reason limiting voltage / current output and concentration efficiency. Optimizing aeration at the aerobic biological cathode is an effective way to solve the performance problems of aerobic biological cathodes. If the aeration pipe is designed as a core component of the aerobic biological cathode, its performance will directly affect the dissolved oxygen supply and the aerobic reaction rate at the cathode.

[0005] In view of this, based on the research findings, a high-performance aerobic biological cathode electrode was designed and developed to improve the activity of cathode microorganisms and reduce the internal resistance of the system, thereby enhancing its overall performance in the treatment of biological wastewater and the extraction of concentrated nutrient solution. Utility Model Content

[0006] The purpose of this invention is to provide an aerobic biological cathode for nutrient solution concentration. By optimizing the aeration and mass transfer effects of the cathode, the ohmic resistance of the aerobic biological cathode is reduced, thereby increasing the power density and nutrient solution concentration efficiency of the system and solving the problems described in the background art.

[0007] The technical solution of this utility model is implemented as follows:

[0008] An aerobic biocathode for nutrient solution concentration includes a cation exchange membrane rolled into a cylindrical shape and an anion exchange membrane rolled into a cylindrical shape. The cation exchange membrane is disposed inside the anion exchange membrane. The tops of the cation exchange membrane and the tops of the anion exchange membrane are sealed together to form an annular upper junction, and the bottoms of the cation exchange membrane and the anion exchange membrane are sealed together to form an annular lower junction, thus forming a concentration membrane roll. A space exists between the cation exchange membrane and the anion exchange membrane to form a cylindrical concentration chamber. The top of the concentration chamber is connected to an inlet water pipe leading to the outside, and the bottom of the concentration chamber is connected to a outlet water pipe leading to the outside. The aerobic biocathode also includes a cylindrical carbon felt surrounding the outside of the concentration membrane roll, and an aeration pipe surrounding the bottom of the carbon felt. The aeration pipe has multiple aeration holes on its wall and an air inlet pipe connected to it.

[0009] When using the above scheme, the aerobic biological cathode is placed in the microbial electro-desalination reactor, and the hollow anode area at the center of the thickening membrane roll is used to insert the anode with attached electrogenic microorganisms. During the reaction, the electrogenic microorganisms on the anode oxidize, transform, and decompose the organic matter in the brewing wastewater, releasing electrons. The electrons are transferred to the cathode made of carbon felt through an external circuit. The oxygen provided by the aeration pipe can effectively reduce gas short circuits, improve the activity and mass transfer effect of the microorganisms on the electrode, reduce the ohmic resistance of the cathode, and improve the power density and concentration efficiency of the system. Oxygen is reduced at the cathode as an electron acceptor. At the same time, under the action of the electric field, the useful ions in the biological wastewater are transferred to the concentration chamber through the cation exchange membrane. The target liquid is injected into the concentration chamber through the water inlet and outlet pipes. The target liquid absorbs the useful ions, realizing the concentration of the nutrient solution.

[0010] By setting carbon felt as the cathode, the good conductivity, low resistivity, and good biocompatibility of carbon felt facilitate the enrichment of microorganisms, improve microbial activity, and have a good mass transfer effect.

[0011] The mass transfer effect of this aerobic biological cathode is enhanced as the aeration effect is improved. According to experimental data, it can increase oxygen mass transfer efficiency by 15%, reduce system internal resistance by 30%, and increase power density by 20%. It not only has stable performance, but also accelerates the nutrient solution concentration rate.

[0012] A further technical solution is to fill the concentration chamber with a supporting skeleton.

[0013] When using the above scheme, by setting up a support frame, not only can stable structural strength be provided, but also stable support can be provided for the cation exchange membrane and anion exchange membrane, ensuring that the cation exchange membrane and anion exchange membrane are not easily deformed during operation, while also avoiding a reduction in the flow rate of the concentration chamber.

[0014] A further technical solution is that the supporting frame is a supporting grid frame.

[0015] A further technical solution is that the carbon felt has a thickness of 3-10 mm, a resistivity of less than 5 × 10⁻³ Ω·m, and a specific surface area greater than 1500 m². 2 / g.

[0016] A further technical solution is that the aeration holes on the wall of the aeration pipe have a pore size of 0.1-0.5 mm and a pore density of 100-200 pores / cm³. 2 .

[0017] A further technical solution is that the carbon felt is soaked in an acid solution for at least 2 hours, rinsed with deionized water until neutral, and then subjected to a high-temperature activation treatment at 300-400°C.

[0018] A further technical solution is that the aeration pipe is a flexible TPU pipe with a wall thickness of 0.5-2.0 mm.

[0019] When using the above solution, the aeration pipe is made of TPU material, a flexible polymer material, which makes the aeration pipe corrosion resistant and can be arranged in a close and circumferential manner to promote uniform air distribution.

[0020] A further technical solution is to use a carbon felt with a thickness of 4.9–5.1 mm.

[0021] A further technical solution is to use an aeration pipe with an inner diameter of 60-68 mm.

[0022] A further technical solution is to have a pore size of 0.18–0.22 mm and a pore density of 150 pores / cm³. 2 And it is evenly distributed on the wall of the aeration pipe.

[0023] The beneficial effects of this utility model are as follows:

[0024] 1. Optimized electron transport: Electrons are transferred to the carbon felt cathode through an external circuit, and the oxygen provided by the aeration pipe reduces gas short circuits, thereby improving microbial activity and mass transfer efficiency.

[0025] 2. Improved system performance: Reduced cathode ohmic resistance, improved system power density and concentration efficiency.

[0026] 3. Advantages of cathode materials: Carbon felt cathodes have good conductivity, low resistivity and biocompatibility, which facilitates the accumulation of microorganisms and improves their activity.

[0027] 4. Enhanced mass transfer effect: The mass transfer effect of the aerobic biological cathode is improved with the aeration effect, which can improve oxygen mass transfer efficiency, reduce system internal resistance, and achieve increased power density.

[0028] 5. Stable and efficient performance: The solution is not only stable in performance, but also accelerates the concentration rate of nutrient solution. Attached Figure Description

[0029] Figure 1 This is a three-dimensional schematic diagram of the present invention;

[0030] Figure 2 This is a top view of the present invention;

[0031] Figure 3 This is a front sectional view of the present invention.

[0032] In the diagram, 1. Carbon felt, 2. Upper joint, 3. Water inlet pipe, 4. Cation exchange membrane, 5. Anion exchange membrane, 6. Aeration pipe, 7. Air inlet pipe, 8. Hollow anode area, 9. Drain pipe, 10. Support grid frame, 11. Lower joint. Detailed Implementation

[0033] To better understand the technical content of this utility model, specific embodiments are provided below, and the utility model will be further described in conjunction with the accompanying drawings.

[0034] See Figures 1 to 3 An aerobic biological cathode for nutrient solution concentration includes a cation exchange membrane 4 rolled into a cylindrical shape and an anion exchange membrane 5 rolled into a cylindrical shape. The cation exchange membrane 4 is disposed inside the anion exchange membrane 5. The top of the cation exchange membrane 4 and the top of the anion exchange membrane 5 are sealed together to form an annular upper junction 2. The bottom of the cation exchange membrane 4 and the bottom of the anion exchange membrane 5 are sealed together to form an annular lower junction 11, thereby forming a concentration membrane roll.

[0035] The upper joint 2 and the lower joint 11 can be sealed by adhesive or sewing.

[0036] A space exists between the cation exchange membrane 4 and the anion exchange membrane 5 to form a ring-shaped concentration chamber. The top of the concentration chamber is connected to an inlet water pipe 3 leading to the outside, and the bottom of the concentration chamber is connected to a outlet water pipe 9 leading to the outside.

[0037] It should be noted that the cation exchange membrane 4 is an exchange membrane that allows cations to pass through, and the anion exchange membrane 5 is an exchange membrane that allows anions to pass through. Those skilled in the art can select the appropriate exchange membrane according to the useful ions to be collected, which is a common technique in the field. The specific models of the cation exchange membrane 4 and the anion exchange membrane 5 are not specified here, but this does not affect those skilled in the art from selecting the specific models according to actual needs to achieve the technical solution and technical effect of this disclosure.

[0038] Preferably, the concentrated membrane roll is in the shape of a cylindrical ring.

[0039] Preferably, the concentration chamber is also filled with a supporting skeleton.

[0040] Preferably, the supporting frame is a supporting grid frame 10.

[0041] The hollow anode region 8 is located at the center of the concentration membrane roll. It should be noted that a separate section is attached to illustrate the hollow anode region 8. Figure 1 The color of the cation exchange membrane 4 was not filled in the hollow anode region 8.

[0042] The aerobic biocathode also includes a ring-shaped carbon felt 1 surrounding the anion exchange membrane 5.

[0043] Preferably, the carbon felt 1 has a thickness of 5 mm, a resistivity of less than 5 × 10⁻³ Ω·m, and a specific surface area greater than 1500 m². 2 / g.

[0044] Preferably, the carbon felt 1 is soaked in a 1 mol / L nitric acid solution for 2 hours to remove surface impurities; it is then rinsed with deionized water until neutral; and subsequently activated at 400°C under nitrogen protection to enhance surface porosity and biocompatibility.

[0045] The aerobic biological cathode also includes an aeration pipe 6 that surrounds the bottom of the carbon felt 1. The aeration pipe 6 can be made into a loop tube with the ends connected, or it can be made into a loop tube that is closed at both ends. The aeration pipe 6 has multiple aeration holes on its wall, and an air inlet pipe 7 is also connected to the aeration pipe 6.

[0046] Preferably, the aeration pipe 6 is a flexible TPU pipe with an inner diameter of 65 mm, a wall thickness of 0.5 mm, a pore size of 0.2 mm, and a pore density of 150 pores / cm³. 2 And it is evenly distributed on the wall of the aeration pipe 6.

[0047] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An aerobic biological cathode for nutrient solution concentration, characterized in that: The device includes a cation exchange membrane rolled into a cylindrical shape and an anion exchange membrane rolled into a cylindrical shape. The cation exchange membrane is located inside the anion exchange membrane. The tops of the cation exchange membrane and the tops of the anion exchange membrane are sealed together to form an annular upper junction, and the bottoms of the cation exchange membrane and the anion exchange membrane are sealed together to form an annular lower junction, thus forming a concentration membrane roll. There is a space between the cation exchange membrane and the anion exchange membrane to form a cylindrical concentration chamber. The top of the concentration chamber is connected to an inlet water pipe leading to the outside, and the bottom of the concentration chamber is connected to a outlet water pipe leading to the outside. The aerobic biocathode also includes a cylindrical carbon felt surrounding the outside of the concentration membrane roll, and an aeration pipe surrounding the bottom of the carbon felt. The aeration pipe has multiple aeration holes on its wall and an air inlet pipe connected to it.

2. The aerobic biological cathode for nutrient solution concentration according to claim 1, characterized in that: The concentration chamber is also filled with a supporting skeleton.

3. An aerobic biological cathode for nutrient solution concentration according to claim 2, characterized in that: The supporting frame is a supporting grid frame.

4. An aerobic biological cathode for nutrient solution concentration according to any one of claims 1-3, characterized in that: The carbon felt has a thickness of 3-10 mm, a resistivity of less than 5 × 10⁻³ Ω·m, and a specific surface area greater than 1500 m². 2 / g.

5. An aerobic biological cathode for nutrient solution concentration according to claim 1, characterized in that: The aeration holes on the wall of the aeration pipe have a diameter of 0.1-0.5 mm and a pore density of 100-200 pores / cm³. 2 .

6. An aerobic biological cathode for nutrient solution concentration according to claim 4, characterized in that: The carbon felt is soaked in an acid solution for at least 2 hours, then rinsed with deionized water until neutral, and then subjected to high-temperature activation treatment at 300-400℃.

7. An aerobic biological cathode for nutrient solution concentration according to claim 5, characterized in that: The aeration pipe is a flexible TPU pipe with a wall thickness of 0.5-2.0 mm.

8. An aerobic biological cathode for nutrient solution concentration according to claim 4, characterized in that: The thickness of the carbon felt is 4.9–5.1 mm.

9. An aerobic biological cathode for nutrient solution concentration according to claim 7, characterized in that: The inner diameter of the aeration pipe is 60-68 mm.

10. An aerobic biological cathode for nutrient solution concentration according to claim 9, characterized in that: The aeration holes have a diameter of 0.18–0.22 mm and a pore density of 150 pores / cm³. 2 And it is evenly distributed on the wall of the aeration pipe.

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