Microbial electrosynthesis device and application thereof

Abstract

The invention relates to a microbial electrosynthesis device and application thereof, the microbial electrosynthesis device comprises a reactor, an anode chamber, a removal chamber, a recovery chamber and a biological cathode chamber are sequentially arranged in the reactor, the biological cathode chamber and the recovery chamber are separated by an anion exchange membrane, and the removal chamber and the anode chamber are separated by an anion exchange membrane. The removal chamber and the recovery chamber are separated by a cation exchange membrane; a biological cathode chamber; a biological cathode is arranged in the biological cathode chamber, an anode is arranged in the anode chamber, and the biological cathode and the anode are electrically connected with a direct-current power supply. According to the invention, an electric field is applied through the anode and the biological cathode, carbon dioxide is reduced in the biological cathode chamber to synthesize organic acid, the eutrophic water body is treated in the removal chamber, and nitrogen and phosphorus nutrient substances in the eutrophic water body and the organic acid synthesized in the cathode chamber are recovered in the recovery chamber by utilizing the characteristic that the external electric field drives transmembrane migration of ionic substances; the microbial electrochemical technology is simultaneously used for eutrophic water body treatment and carbon dioxide gas biological utilization.

Description

Technical Field

[0001] The present invention relates to the technical fields of water environmental protection and biosynthesis technology, and particularly to a microbial electrosynthesis device and its application. Background Art

[0002] The development of carbon capture technology is very important for solving global warming. Among them, microbial electrosynthesis is a new type of carbon capture technology. Based on microbial extracellular electron transfer (EET), the biocathode provides reducing power, and CO2 can be fixed and reduced to chemical products such as acetic acid. Microbial electrosynthesis is the development of traditional carbon capture technology, which is beneficial to solving the problem of uneven distribution of energy in time and space. Fixing CO2 and reducing it into chemicals can effectively alleviate the greenhouse effect in the future. At present, microbial electrosynthesis is not suitable for industrial production because the high production cost and low-value products limit its commercialization, and the single function and structure weaken its economic competitiveness. Therefore, it is hoped to improve the economic competitiveness by adjusting the device structure and increasing functionality.

[0003] At the same time, the excessive discharge of agricultural and industrial wastewater will lead to an increase in the content of inorganic nutrients (especially nitrogen and phosphorus) in water bodies, thus causing eutrophication of water bodies in rivers and lakes, which is harmful to the aquatic ecosystem and human health. The traditional wastewater treatment method, the anaerobic / anoxic / aerobic (A2O) process, focuses on removal rather than recovery and does not achieve the purpose of resource utilization. The bioelectrochemical system (BESs) is a multifunctional platform that utilizes the characteristic of driving the directional migration of ionic substances by electric energy. Microbial desalination cells commonly used for seawater desalination; microbial batteries used for the removal and recovery of heavy metals; and various nutrient recovery ponds used for the removal and recovery of actual domestic wastewater. The structures and functions of their devices are different, but they are all based on the characteristic of generating electric energy by microbial fuel cells (MFCs) to drive the migration of ionic substances in order to achieve the purpose of removing and recovering different ions. Based on the characteristic of generating electric energy by microbial fuel cells (MFCs) to drive the migration of ionic substances in order to achieve the purpose of removing and recovering different ions.

[0004] At present, there are few reports on the simultaneous recovery of nutrients in microbial electrosynthesis. Therefore, it is hoped that coupling nutrient recovery in microbial electrosynthesis can solve the problem of wastewater treatment while carrying out microbial electrosynthesis, which will provide a good strategy for the industrial development of microbial electrosynthesis. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a microbial electrosynthesis device and its application, which realizes the simultaneous use of microbial electrochemistry technology for the recovery of nutrients in wastewater and the biological utilization of carbon dioxide gas.

[0006] The present invention is implemented by the following scheme: A microbial electrosynthesis device includes a reactor. An anodic chamber, a removal chamber, a recovery chamber, and a biocathodic chamber are sequentially arranged in the reactor. The biocathodic chamber and the recovery chamber are separated by an anion exchange membrane. The removal chamber and the anodic chamber are separated by an anion exchange membrane. The removal chamber and the recovery chamber are separated by a cation exchange membrane; a biocathodic chamber; a biocathode is arranged in the biocathodic chamber, and an anode is arranged in the anodic chamber. The biocathode and the anode are electrically connected to a DC power supply.

[0007] Further, an electrolyte solution is arranged in the anodic chamber, the water body to be treated is arranged in the removal chamber, an electrolyte solution is arranged in the recovery chamber, and a biological culture solution and an inoculum are arranged in the biocathodic chamber; the biological culture solution provides necessary nutrient components for the growth of microorganisms, such as an artificially prepared solution containing C, N, P, trace elements, vitamins, etc.

[0008] The preparation principle of the anodic chamber solution is to have the same conductivity as the solution in the removal chamber to reduce concentration polarization. When the water body to be treated in the removal chamber is an eutrophic water body (conductivity is 900 μs / cm), the anodic chamber solution is an electrolyte solution with a conductivity of 900 μs / cm. When the removal chamber needs to treat other types of water bodies (such as urine) and recover nitrogen and phosphorus, the anodic chamber solution can be adjusted to the corresponding conductivity; the electrolyte solution includes but is not limited to NaCl solution, KCl solution, phosphate buffer solution and their mixtures, etc.

[0009] The added in the removal chamber is an artificially simulated eutrophic water body, in which ammonia nitrogen (3 mg / L), nitrate nitrogen (3 mg / L), phosphate radical (0.6 mg / L), COD (20 mg / L), and then NaCl is added to adjust the conductivity to 900 μs / cm. The removal chamber can also be used when treating other types of water bodies (such as urine) and recovering nitrogen and phosphorus.

[0010] The preparation principle of the recovery chamber solution is that when the removal chamber needs to recover nitrogen and phosphorus from treating an eutrophic water body (conductivity is 900 μs / cm), the recovery chamber solution is an electrolyte solution with a conductivity of 900 μs / cm. When treating other wastewater, the electrolyte solution used as the recovery chamber solution can be adjusted to the corresponding conductivity. The electrolyte solution includes but is not limited to NaCl solution, KCl solution, phosphate buffer solution and their mixtures, etc.

[0011] Further, the inoculum uses activated sludge, and the inoculation amount of the activated sludge is 5%; constant charging operation is carried out at 7 mA for 14 days, and the cathode biofilm gradually matures. The judgment basis is that a certain amount of acetic acid accumulates (about 0.8 g / L).

[0012] Further, the components of the biological culture solution are: KH2PO4 4.4 g / L, K2HPO4 2.6 g / L, NH4Cl 0.31 g / L, MgCl2·6H2O 0.2 g / L, Na2SO4 0.05 g / L, NaHCO3 4.2 g / L, 2-BES 1.0 g / L, and yeast extract 0.5 g / L.

[0013] Further, considering the electrical conductivity of the anode and the need for the biocathode to have both good electrical conductivity and a high specific surface area, the biocathode uses carbon felt, and the anode uses platinum-plated titanium mesh, preferably with a thickness of 5 mm and a cross-sectional area of 7 cm 2 of carbon felt.

[0014] By applying a constant-current electric field between the anode and the biocathode, adding simulated eutrophic water to the removal chamber between the anode and the biocathode, and under the drive of the electric field, the nutrient salt ions migrate to the anode chamber and the recovery chamber respectively, achieving separation and recovery. The cathode used is a biocathode, and by inoculating activated sludge, acetic acid-producing bacteria are enriched. In the cathode chamber, the electrode provides electrons and acts as a reducing power, capable of fixing CO2 and reducing it to acetic acid. Under the drive of the electric field, acetate ions migrate to the recovery chamber. The present invention can achieve the purpose of recovering nutrient salts from wastewater while performing microbial electrosynthesis of acetic acid.

[0015] Different polluted waters can be added to the removal chamber to achieve the purpose of removing and recovering nutrient salts. In the cathode chamber, in addition to using the biocathode to produce acetic acid, chemical cathodes based on indium or tin metal catalysts can also be used to reduce CO2 to produce formic acid. It can be seen that the cathode in the cathode chamber has the ability to reduce CO2 to produce organic acids (acetic acid or formic acid), and the removal chamber has the ability to treat different wastewaters.

[0016] Another technical solution of the present invention: An application of the microbial electrosynthesis device as described above in the recovery of wastewater nutrients. First, the anode and the biocathode are connected in series through a DC power supply, and a constant current is applied to the microbial electrosynthesis device. The biocathode is used to reduce CO2 for acetic acid synthesis. Under the drive of the electric field, acetate ions migrate to the recovery chamber through the anion exchange membrane; eutrophic water is added to the removal chamber, and the positive nutrient salt ions migrate to the recovery chamber through the cation exchange membrane, and the negative nutrient salt ions migrate to the anode chamber through the anion exchange membrane.

[0017] Depending on the inoculum, the types of organic acids will vary. The DC power supply includes power sources that directly output DC electrical energy such as dry batteries, and also includes power supply devices that can convert AC power sources into DC, or battery test systems and electrochemical workstations that can provide DC power. The charging current density depends on the cathode performance. Usually, for the biocathode, it is 0.1 - 10 mA / cm 2In the present invention, when charging a microbial electrosynthesis device equipped with a biocathode for coupled nutrient recovery using a DC power supply, the charging current is preferably 1 mA / cm 2 .

[0018] Compared with the prior art, the present invention has the following beneficial effects: By applying an electric field through the anode and the biocathode, the present invention reduces carbon dioxide to synthesize organic acids in the biocathode chamber, treats eutrophic water bodies in the removal chamber, and utilizes the characteristic of the applied electric field to drive the transmembrane migration of ionic substances to recover nitrogen and phosphorus nutrients in the eutrophic water bodies and the organic acids synthesized in the cathode chamber in the recovery chamber; the present invention realizes the simultaneous use of microbial electrochemical technology for treating eutrophic water bodies and biologically utilizing carbon dioxide gas.

[0019] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following will further elaborate on the present invention through specific embodiments and relevant drawings. Description of the Drawings

[0020] Figure 1 is a schematic structural diagram of the microbial electrosynthesis device of the present invention; Figure 2 is a schematic diagram of the biocathode formation stage of the microbial electrosynthesis device of the present invention; Figure 3 is a schematic diagram of the ammonia nitrogen change when the microbial electrosynthesis device of the present invention is used for nitrogen and phosphorus recovery and acetic acid synthesis; Figure 4 is a schematic diagram of the nitrate nitrogen change when the microbial electrosynthesis device of the present invention is used for nitrogen and phosphorus recovery and acetic acid synthesis; Figure 5 is a schematic diagram of the phosphorus change when the microbial electrosynthesis device of the present invention is used for nitrogen and phosphorus recovery and acetic acid synthesis; Figure 6 is a schematic diagram of the acetic acid change when the microbial electrosynthesis device of the present invention is used for nitrogen and phosphorus recovery and acetic acid synthesis; Explanation of the reference numerals in the drawings: 1 - biocathode; 2 - biocathode chamber; 3 - anion exchange membrane; 4 - recovery chamber; 5 - cation exchange membrane; 6 - removal chamber; 7 - anion exchange membrane; 8 - anode chamber; 9 - anode; 10 - DC power supply. Detailed Embodiments

[0021] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanations for the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0022] It should be noted that the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] Example 1: As Figures 1 - 2 shown, a microbial electrosynthesis device includes a reactor, in which an anode chamber, a removal chamber, a recovery chamber, and a biocathode chamber are sequentially arranged. The biocathode chamber and the recovery chamber are separated by an anion exchange membrane, the removal chamber and the anode chamber are separated by an anion exchange membrane, and the removal chamber and the recovery chamber are separated by a cation exchange membrane; a biocathode chamber; a biocathode is arranged in the biocathode chamber, an anode is arranged in the anode chamber, and the biocathode and the anode are electrically connected to a DC power supply; the biocathode is made of carbon felt, and the anode is made of platinum-plated titanium mesh.

[0024] Biocathode formation stage: The conductivities of the anode chamber, the removal chamber, and the recovery chamber are adjusted to 900 μs / cm with NaCl solution. A biological culture solution and an inoculum are arranged in the biocathode chamber; the inoculum is activated sludge, and the inoculation amount of the activated sludge is 5%. The components of the biological culture solution are: KH2PO4 4.4 g / L, K2HPO4 2.6 g / L, NH4Cl 0.31 g / L, MgCl2·6H2O 0.2 g / L, Na2SO4 0.05 g / L, NaHCO3 4.2 g / L, 2-BES 1.0 g / L, and yeast extract 0.5 g / L.

[0025] Use a DC power supply to charge at a constant current of 7 mA until a certain amount of acetic acid accumulates in the biocathode chamber, that is, the biocathode is prepared.

[0026] Example 2: As Figures 3 - 6As shown in the figure, during the nutrient recovery stage: after a bio-cathode is formed in an embodiment, the solution in the bio-cathode chamber is centrifuged and rinsed, and then fresh bio-culture solution is added. The components of the bio-culture solution are as follows: KH2PO4 4.4 g / L, K2HPO4 2.6 g / L, NH4Cl 0.31 g / L, MgCl2·6H2O 0.2 g / L, Na2SO4 0.05 g / L, NaHCO3 4.2 g / L, 2-BES 1.0 g / L, and yeast extract 0.5 g / L. At the same time, the solutions in the recovery chamber and the anode chamber are replaced with NaCl solution again to adjust the conductivity to 900 μs / cm, and the solution in the removal chamber is replaced with eutrophic water body, with the specific components being: ammonia nitrogen (3 mg / L), nitrate nitrogen (3 mg / L), phosphate (0.6 mg / L), COD (20 mg / L), and then the conductivity is adjusted to 900 μs / cm with NaCl, and the solution in the removal chamber can be cyclically replaced.

[0027] After the coupled nutrient recovery is completed, the performance of its recovered nutrients can be investigated. The recovery rate is calculated by the amounts of phosphate and nitrate nitrogen recovered in the anode chamber, and the amounts of ammonia nitrogen and acetic acid recovered in the recovery chamber. The removal rate is calculated by the amounts of ammonia nitrogen, nitrate nitrogen, and phosphate removed in the removal chamber. As Figure 3 , 4 shown in Figure 5.

[0028] For any of the technical solutions disclosed in the present invention above, unless otherwise stated, if it discloses a numerical range, then the disclosed numerical range is a preferred numerical range. Any person skilled in the art should understand that the preferred numerical range is only the numerical values with obvious technical effects or representativeness among many feasible numerical values. Since there are too many numerical values to list exhaustively, the present invention only discloses some numerical values to illustrate the technical solutions of the present invention, and the above-listed numerical values should not constitute a limitation to the protection scope of the present invention.

[0029] If the present invention discloses or involves components or structural parts that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: detachably fixed connection (for example, connected with bolts or screws), or can also be understood as: non-detachable fixed connection (for example, riveting, welding). Of course, the mutual fixed connection can also be replaced by an integral structure (for example, manufactured by integral forming using casting process) (except when it is obviously impossible to adopt the integral forming process).

[0030] In addition, for the terms used to represent the positional relationship or shape in any of the technical solutions disclosed in the present invention above, unless otherwise stated, their meanings include the states or shapes that are approximate, similar, or close to them.

[0031] Any component provided by the present invention can either be assembled from multiple individual components or be a single component manufactured by an integral forming process.

[0032] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A microbial electrosynthesis device, characterized in that: It includes a reactor, in which there are successively an anodic chamber, a removal chamber, a recovery chamber and a biocathodic chamber. The biocathodic chamber and the recovery chamber are separated by an anion exchange membrane. The removal chamber and the anodic chamber are separated by an anion exchange membrane. The removal chamber and the recovery chamber are separated by a cation exchange membrane; a biocathodic chamber; a biocathode is arranged in the biocathodic chamber, and an anode is arranged in the anodic chamber. The biocathode and the anode are electrically connected to a DC power supply.

2. The microbial electrosynthesis device according to claim 1, wherein: An electrolyte solution is arranged in the anodic chamber, the water body to be treated is arranged in the removal chamber, an electrolyte solution is arranged in the recovery chamber, and a biological culture solution and an inoculum are arranged in the biocathodic chamber.

3. The microbial electrosynthesis device according to claim 2, wherein: The inoculum adopts activated sludge, and the inoculation amount of the activated sludge is 5%.

4. The microbial electrosynthesis device according to claim 2, characterized in that: The components of the biological culture solution are: KH2PO4 4.4 g / L, K2HPO4 2.6 g / L, NH4Cl 0.31 g / L, MgCl2·6H2O 0.2 g / L, Na2SO4 0.05 g / L, NaHCO3 4.2 g / L, 2-BES 1.0 g / L, yeast extract 0.5 g / L.

5. The microbial electrosynthesis device according to claim 1, wherein: The biocathode adopts carbon felt, and the anode adopts platinum-plated titanium mesh.

6. Use of the microbial electrosynthesis device according to claim 1 in wastewater nutrient recovery, characterized in that: First, the anode and the biocathode are connected in series through a DC power supply to apply a constant current to the microbial electrosynthesis device. The biocathode is used to reduce CO2 for acetic acid synthesis. Under the drive of the electric field, acetate ions migrate to the recovery chamber through the anion exchange membrane; the eutrophic water body is added to the removal chamber, in which the positive nutrient salt ions migrate to the recovery chamber through the cation exchange membrane, and the negative nutrient salt ions migrate to the anodic chamber through the anion exchange membrane.

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