Electrocatalytic membrane filtration-microbial fuel cell coupling system and application thereof

Abstract

The invention provides an electro-catalysis membrane filtration-microbial fuel cell coupling system and application thereof, and belongs to the field of wastewater treatment. The wastewater comes from oil and gas field wastewater, including but not limited to fracturing flow-back fluid and produced fluid. According to the invention, an electrocatalytic oxidation technology, a membrane filtration technology and a microbial fuel cell technology are coupled, and modified activated carbon with the characteristic of forming hydrogen peroxide through electrocatalytic oxygen reduction is applied to electrocatalytic membrane filtration and microbial fuel cells; the dual degradation effect of pollutants in the oil and gas field wastewater and the effect of efficiently removing the hardness of calcium and magnesium are achieved, and high-efficiency and low-energy-consumption recycling treatment of the oil and gas field wastewater is completed.

Description

Technical Field

[0001] The invention belongs to the field of wastewater treatment, and relates to an electrocatalytic membrane filtration-microbial fuel cell coupling system and an invention for using the system to treat and remove pollutants in wastewater. Background Art

[0002] Fracturing flowback fluid refers to the liquid that flows back through the wellbore during large-scale volume fracturing. Fracturing flowback fluid contains unbroken fracturing fluid, breakers, various fracturing aids, and impurities such as rocks and silt. If the untreated or simply treated flowback fluid is directly discharged into the environment, it will cause serious damage to the ecological environment. The recycling and reuse of flowback fluid is one of the effective ways to treat oil and gas field wastewater. The development of efficient oil and gas field wastewater reuse technology has extremely far-reaching significance.

[0003] Membrane treatment technology is a very promising field for wastewater treatment. However, the current limitations of conventional membrane treatment of high-salinity organic wastewater include membrane fouling and poor treatment effects. Electrosorption desalination can remove salt without a separation membrane and has been shown to exhibit superior desalination performance compared to conventional electrodialysis and reverse osmosis treatments. Electrocatalytic membrane filtration is a widely accepted technology for removing salt and partially degrading organic pollutants. Microbial fuel cells (MFCs) can use the metabolism of microorganisms to convert chemical energy in organic matter into electrical energy. When the two are coupled, electrocatalytic membrane filtration can intercept suspended matter in wastewater and effectively remove salt from wastewater. The intermediates or incompletely degraded organic matter produced in the process can be further utilized and converted into substrates for microorganisms in MFC, thereby improving the removal efficiency of organic pollutants in the entire system. At the same time, the electrical energy generated by MFC can provide energy support for electrocatalytic membrane filtration, thereby reducing external energy demand and achieving effective energy recovery and utilization. Therefore, it is a promising work to achieve the coupling of electrocatalytic membrane filtration and MFC to treat oil and gas field wastewater.

[0004] The present invention also applies modified activated carbon having the characteristic of electrocatalytic oxygen reduction to form hydrogen peroxide to electrocatalytic membrane filtration and microbial fuel cells, thereby achieving a dual degradation effect of pollutants in oil and gas field wastewater and realizing the treatment of oil and gas field wastewater. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention aims to provide an electrocatalytic membrane filtration-microbial fuel cell coupling system and its application. The coupling system provided by the present invention couples electrocatalytic oxidation technology, membrane filtration technology, capacitive deionization technology, electric precipitation active technology and microbial fuel cell technology, giving full play to the advantages of the five technologies and avoiding the shortcomings of the five technologies, so as to complete the high-efficiency and low-energy consumption reuse treatment of oil and gas field wastewater.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention provides an electrocatalytic membrane filtration-microbial fuel cell coupling system, comprising a pretreatment module, an electrocatalytic membrane filtration module and a microbial fuel cell module; the pretreatment module, the electrocatalytic membrane filtration module and the microbial fuel cell module are connected in series in sequence, the electrocatalytic membrane filtration module is connected to a direct current power supply, the microbial fuel cell module comprises a microbial fuel cell and an aeration system, the aeration system aerates the cathode of the microbial fuel cell through an air pump, and the electricity generated by the microbial fuel cell module is recycled to the electrocatalytic membrane filtration module.

[0008] Furthermore, the pre-treatment module is used to simply filter out large particles, silt, floating oil and other impurities in the water.

[0009] Furthermore, the cathode of the electrocatalytic membrane filtration module includes an insulating frame, a conductive filter membrane, a conductive coating, and a water pump; the insulating frame and the conductive filter membrane constitute a flat box-shaped body, the two sides of the box-shaped body with the largest area are the conductive filter membrane, the surrounding of the conductive filter membrane is supported and connected by the insulating frame, the box-shaped body has a reserved water outlet, and the water outlet is connected to the water pump through a pipe; the conductive coating is arranged on the two outer sides of the box-shaped body, which is a container with micropores on the surface, and the container contains a filler with electrocatalytic and adsorption properties.

[0010] Furthermore, the insulating frame of the reserved water outlet is made of plastic, preferably a rectangular or cylindrical acrylic plate frame;

[0011] Furthermore, the conductive filter membrane is a conductive carbon material with low cost and excellent conductive performance, such as carbon fiber cloth, carbon fiber cloth coated with polyvinylidene fluoride PVDF, or carbon felt;

[0012] Furthermore, the conductive coating is detachable and can be movably and tightly mounted on the outside of the insulating frame;

[0013] Furthermore, the filler in the conductive layer is activated carbon particles loaded with cobalt and cerium (CoCe / AC) or other conductive granular adsorption materials with electrocatalytic redox properties;

[0014] Furthermore, the electrocatalytic membrane filtration module is particularly suitable for removing calcium and magnesium hardness;

[0015] Furthermore, the microbial fuel cell is a dual-chamber air cathode microbial fuel cell; the upper part is an anode chamber, water enters from the bottom of the anode chamber, and the upper part is a cathode chamber;

[0016] Furthermore, the anode chamber of the microbial fuel cell is filled with a layer of activated carbon particles loaded mainly with Shewanella;

[0017] Furthermore, the cathode chamber of the microbial fuel cell is filled with activated carbon particles loaded with cobalt and cerium (CoCe / AC) to catalyze the reduction of organic pollutants to produce hydrogen peroxide to achieve further degradation of organic matter;

[0018] Furthermore, the electrocatalytic membrane filtration module and the microbial fuel cell module in the present invention use the same activated carbon particles loaded with cobalt and cerium (CoCe / AC).

[0019] Furthermore, the CoCe / AC preparation process is as follows: a certain amount of Co(NO 3 ) 2 and Ce(NO 3 ) 2 Add an appropriate amount of deionized water, then add a nitrogen source and stir to obtain a homogeneous solution, the mass fraction of the nitrogen source in the homogeneous solution is 2-3wt%, take an appropriate amount of water-washed activated carbon, mix by equal volume immersion method and ultrasonic treatment, then dry in a blast drying oven at 75-85°C overnight. The obtained dry particles are further sintered at high temperature in a muffle furnace.

[0020] Furthermore, the mass ratio of cobalt to cerium used in the CoCe / AC is 0.15:1 to 0.3:1; the immersion mixing and ultrasonic treatment time is 30 min to 60 min.

[0021] Furthermore, urea or melamine is used as a nitrogen source in the CoCe / AC preparation process;

[0022] Furthermore, the high temperature sintering temperature is 400-550° C. and the time is 2-3 hours.

[0023] The present invention also provides an application of an electrocatalytic membrane filtration-microbial fuel cell coupling system described in the above technical solution, which is applied to the treatment of oil and gas field wastewater, specifically as follows: the wastewater enters the pretreatment module to remove large particle waste; then enters the electrocatalytic membrane filtration module, and the water in the box-shaped body of the insulating frame is pumped out by a water pump, forming a negative pressure in the box-shaped body of the insulating frame, so that the wastewater flows through the conductive layer and the conductive filter membrane. On the one hand, the electroprecipitation active technology and the capacitive deionization technology can be used to effectively remove the mineral salts of calcium and magnesium ions in the oil and gas field wastewater. On the other hand, physical interception, electrical adsorption and electrocatalysis technology are used to remove suspended matter in the oil and gas field wastewater and destroy the structure and reduce the toxicity of large molecular organic matter; finally, it enters the microbial fuel cell module to treat the primary wastewater treated by the electrocatalytic membrane filtration module. The MFC can effectively remove the COD in the wastewater to meet the treatment standard.

[0024] The voltage of the DC power supply is: 0.5~1.0V;

[0025] The area of ​​the conductive filter membrane is: 0.1-0.3m3;

[0026] The thickness of the conductive layer is 1.5 to 2.5 cm.

[0027] The wastewater flux of the electrocatalytic membrane filtration module is: 200-300 L·m - 3 h -1

[0028] Beneficial effects of the present invention: The electrocatalytic membrane filtration module in the coupling system provided by the present invention can improve the biodegradability of oil and gas field wastewater and realize effective desalination and decontamination functions, that is, on the one hand, it can utilize electroprecipitation active ionization technology and capacitive deionization technology to realize the effective removal of mineral salts of calcium and magnesium ions in oil and gas field wastewater, and on the other hand, physical interception, electrosorption and electrocatalysis technology can be used to realize the removal of suspended matter and the structural destruction and toxicity reduction of macromolecular organic matter in oil and gas field wastewater. The microbial fuel cell module (MFC) in the coupling system provided by the present invention is used to treat the primary wastewater treated by the electrocatalytic membrane filtration module. The MFC can effectively remove the COD in the wastewater to meet the treatment standards. In addition, the MFC can use the electrical energy generated by organic matter to provide energy support for electrocatalytic membrane filtration. The electrocatalytic membrane filtration-microbial fuel cell coupling system provided by the present invention and its application can effectively remove mineral salts of calcium and magnesium ions, suspended matter and COD in oil and gas field wastewater. The data of the examples show that the present invention can achieve the standard treatment of calcium and magnesium in fracturing flowback fluid and a COD removal rate of 88.8%; and achieve the effective treatment of calcium and magnesium in produced fluid and a COD removal rate of 56.35%. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flow chart of an electrocatalytic membrane filtration-microbial fuel cell coupling system of the present invention;

[0030] Figure 2 A schematic diagram of an electrocatalytic membrane filtration-microbial fuel cell coupling system of the present invention;

[0031] Figure 3 Schematic diagram of the electrocatalytic membrane filtration module of the coupling system;

[0032] Figure 4 Schematic diagram of the microbial fuel cell module of the coupled system. DETAILED DESCRIPTION

[0033] The present invention provides an electrocatalytic membrane filtration-microbial fuel cell coupling system, comprising a pretreatment module, an electrocatalytic membrane filtration module and a microbial fuel cell module; the pretreatment module, the electrocatalytic membrane filtration module and the microbial fuel cell module are connected in series in sequence, the electrocatalytic membrane filtration module is connected to a direct current power supply, the microbial fuel cell module comprises a microbial fuel cell and an aeration system, and the aeration system aerates the cathode of the microbial fuel cell through an air pump.

[0034] The coupling system of the present invention is a water path of a pretreatment module, an electrocatalytic membrane filtration module and a microbial fuel cell module that are sequentially connected. The water path of the electrocatalytic membrane filtration-microbial fuel cell coupling system is described in detail below:

[0035] The waterway of the coupling system of the present invention includes a pretreatment module. The purpose of the pretreatment module is to remove solid particles, suspended colloids, floating oil layers, etc. in oil and gas field wastewater. The present invention does not limit the specific device of the pretreatment module, as long as it can remove solid particles, suspended colloids, floating oil layers, etc. in oil and gas field wastewater, such as filter cloth or screen.

[0036] The water circuit of the coupling system of the present invention includes an electrocatalytic membrane filtration module. Figure 3 The schematic diagram of the electrocatalytic membrane filtration module of the coupling system, wherein the cathode of the electrocatalytic membrane filtration module is composed of a plastic frame with a reserved water outlet, a conductive filter membrane installed on the plastic frame, a movable conductive layer covering the conductive filter membrane, and a pipeline connecting the water outlet and a water pump;

[0037] The plastic frame for the reserved water outlet is preferably a rectangular acrylic plate frame;

[0038] The conductive filter membrane is preferably a carbon fiber cloth coated with PVDF;

[0039] The movable conductive coating is composed of a preferred rectangular container that can be movably mounted on the outside of the plastic frame and a filler with adsorption properties;

[0040] The filling material of the movable conductive layer is activated carbon particles loaded with cobalt and cerium (CoCe / AC);

[0041] The electrocatalytic membrane filtration module in the coupling system provided by the present invention can improve the biodegradability of oil and gas field wastewater and realize effective desalination and decontamination functions. The principle is that a DC power supply is added to the electrocatalytic membrane filtration module immersed in the wastewater to form a stable DC electric field. Under the action of the DC electric field, the cationic salt migrates toward the negatively charged filter membrane; the movable conductive layer is closely connected to the conductive filter membrane, has negative charge, and can physically intercept and electrically adsorb colloids or suspended substances in the oil and gas field wastewater. These substances are catalytically degraded by the filler with electrocatalytic properties in the movable conductive layer, and carbon dioxide is generated, which is conducive to the precipitation of salt ions such as calcium and magnesium on the surface of the electrocatalytic membrane filtration module, and contributes to the hardness of calcium and magnesium; the cationic salt migrated to the cathode will be adsorbed by the intercepted colloidal substances or catalytic degradation intermediates, and will be precipitated and removed under the action of the electrode electric field and membrane surface polarization. The electrocatalytic membrane filtration module in the coupling system provided by the present invention can, on the one hand, utilize electroprecipitation ionization technology and capacitive deionization technology to effectively remove mineral salts of calcium and magnesium ions in oil and gas field wastewater; on the other hand, it can remove suspended matter and destroy the structure and reduce toxicity of macromolecular organic matter in oil and gas field wastewater through physical interception, electrosorption and electrocatalysis technology, thereby increasing the biodegradability of water samples treated by the electrocatalytic membrane filtration module, which is more conducive to subsequent treatment by microbial fuel cells.

[0042] The water circuit of the coupling system of the present invention comprises a microbial fuel cell module, the microbial fuel cell module comprises a microbial fuel cell and an aeration system, and the aeration system aerates the cathode of the microbial fuel cell through an air pump. Figure 4 The schematic diagram of the microbial fuel cell module of the coupling system, wherein the microbial fuel cell is a double-chamber air cathode microbial fuel cell; the anode of the microbial fuel cell is activated carbon layered particles loaded with mainly Shewanella; the cathode of the microbial fuel cell module is CoCe / AC activated carbon particles, and an air pump is used to aerate the cathode.

[0043] In the present invention, the electrocatalytic membrane filtration module and the microbial fuel cell module use the same activated carbon particles loaded with cobalt and cerium (CoCe / AC).

[0044] The mass ratio of cobalt to cerium used in the CoCe / AC is preferably 0.2:1;

[0045] Urea is used as the preferred nitrogen source in the CoCe / AC preparation process;

[0046] The CoCe / AC preparation process is preferably as follows: 0.596 g Co(NO 3 ) 2 and 2.92gCe(NO 3 ) 2100 mL of deionized water was added, followed by urea and stirring to obtain a homogeneous solution, wherein the mass fraction of urea in the homogeneous solution was 2 wt %. 75 g of water-washed activated carbon was mixed by equal volume immersion method and ultrasonically treated for 30 min, and then dried in a 75°C forced air drying oven for 12 h. The obtained dried particles were further heated to 400°C in a muffle furnace at a heating rate of 5°C / min, and annealed for 2 h to obtain the final product, named CoCe / AC.

[0047] The microbial fuel cell module in the coupling system provided by the present invention needs to be domesticated in three stages before it is activated. In the first stage, the electrocatalytic membrane filtration module is preferably used to treat a 1:1 mixture of oil and gas field wastewater and nutrient solution as a substrate for domestication, and when the MFC output voltage is stable, the next stage of domestication can be entered; in the second stage, the electrocatalytic membrane filtration module is preferably used to treat a 2:1 mixture of oil and gas field wastewater and nutrient solution as a substrate for domestication, and when the MFC output voltage is stable, the next stage of domestication can be entered; in the third stage, the electrocatalytic membrane filtration module is used to treat oil and gas field wastewater as a substrate for domestication, and the final output voltage is stable, indicating that the power-producing microorganisms have adapted to the characteristics of the actual wastewater.

[0048] The present invention also provides the application of the electrocatalytic membrane filtration-microbial fuel cell coupling system described in the above technical solution in treating oil and gas field wastewater.

[0049] In the present invention, the oil and gas field wastewater includes fracturing flowback fluid and produced fluid.

[0050] The electrocatalytic membrane filtration-microbial fuel cell coupling system and its application provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0051] The technical solution and drawings of the present invention are further described below through embodiments, which are not intended to limit the protection scope of the present invention.

[0052] Example 1

[0053] The oil and gas field wastewater used in this embodiment is fracturing flowback fluid, in which the calcium ion concentration is 1741.8 mg / L, the magnesium ion concentration is 73.2 mg / L, and the COD is 6250 mg / L.

[0054] The cathode of the electrocatalytic membrane filtration module is composed of a rectangular acrylic plate frame (specification: 12cm×17cm) with a reserved water outlet, two pieces of PVDF carbon fiber cloth (specification: 10cm×15cm) installed on the rectangular frame, a movable conductive CoCe / AC coating tightly covered on the rectangular frame, and a pipeline connecting the water outlet and the water pump. The anode is a carbon fiber cloth cathode, and the two-electrode system without a diaphragm is used. The applied DC voltage is 0.75V, the thickness of the movable conductive coating is 2.0cm, and the flux is 240L·m - 3 h -1 The calcium ion removal rate of the effluent was 78.27%, the magnesium ion removal rate was 40%, and the COD removal rate was 43.2%. The resulting wastewater enters the microbial fuel cell module.

[0055] The startup process of the microbial fuel cell (MFC) in the microbial fuel cell group module is divided into three stages. In the first stage, a 1:1 mixture of the above-obtained wastewater and nutrient solution is preferably used as a substrate for domestication. When the MFC output voltage is stable, the next stage of domestication can be entered. The output voltage of this stage is stable at 0.1-0.2V; in the second stage, a 2:1 mixture of the above-obtained wastewater and nutrient solution is preferably used as a substrate for domestication. When the MFC output voltage is stable, the next stage of domestication can be entered. The output voltage of this stage is stable at 0.4-0.6V; in the third stage, all the above-obtained wastewater is used as a substrate for domestication, and the final output voltage is stable at about 0.7V, indicating that the power-producing microorganisms have adapted to the characteristics of the actual wastewater and the wastewater is treated. Finally, the COD content of the effluent from the microbial fuel cell group module is 700.5mg / L, and the removal rate is 88.8%%

[0056] Example 2

[0057] The oil and gas field wastewater used in this embodiment is produced liquid, wherein the calcium ion concentration is 23128.0 mg / L, the magnesium ion concentration is 326.8 mg / L, and the COD is 1970 mg / L.

[0058] The cathode of the electrocatalytic membrane filtration module is composed of a rectangular acrylic plate frame (specification: 12cm×17cm) with a reserved water outlet, two pieces of PVDF carbon fiber cloth (specification: 10cm×15cm) installed on the rectangular frame, a movable conductive CoCe / AC coating tightly covered on the rectangular frame, and a pipeline connecting the water outlet and the water pump. The anode is a carbon fiber cloth cathode, and the two-electrode system without a diaphragm is used. The applied DC voltage is 0.5V, the thickness of the movable conductive coating is 2.0cm, and the flux is 300L·m - 3 h -1The calcium ion removal rate of the effluent was 31.12%, the magnesium ion removal rate was 18.76%, and the COD removal rate was 12.45%. The resulting wastewater entered the microbial fuel cell module.

[0059] The startup process of the microbial fuel cell (MFC) in the microbial fuel cell group module is divided into three stages. In the first stage, a 1:1 mixture of the above-obtained wastewater and nutrient solution is preferably used as a substrate for domestication. When the MFC output voltage is stable, the next stage of domestication can be entered. The output voltage of this stage is stable at 0.01-0.05; in the second stage, a 2:1 mixture of the above-obtained wastewater and nutrient solution is preferably used as a substrate for domestication. When the MFC output voltage is stable, the next stage of domestication can be entered. The output voltage of this stage is stable at 0.1-0.2V; in the third stage, all the above-obtained wastewater is used as a substrate for domestication, and the final output voltage is stable at about 0.4v, indicating that the power-producing microorganisms have adapted to the characteristics of the actual wastewater and the wastewater is treated. Finally, the COD content of the effluent from the microbial fuel cell group module is 860.2mg / L, and the removal rate is 56.34%

[0060] The present invention provides an electrocatalytic membrane filtration-microbial fuel cell coupling system and its application, which couples electrocatalytic oxidation technology, membrane filtration technology and microbial fuel cell technology, and also applies modified activated carbon with the property of electrocatalytic oxygen reduction to form hydrogen peroxide to electrocatalytic membrane filtration and microbial fuel cells, thereby achieving a dual degradation effect of pollutants in oil and gas field wastewater and an effect of efficiently removing calcium and magnesium hardness, thereby completing a high-efficiency, low-energy consumption reuse treatment of oil and gas field wastewater.

Claims

1. An electrocatalytic membrane filtration-microbial fuel cell coupling system, characterized in that: It includes a pretreatment module, an electrocatalytic membrane filtration module and a microbial fuel cell module; the pretreatment module, the electrocatalytic membrane filtration module and the microbial fuel cell module are connected in series in sequence, the electrocatalytic membrane filtration module is connected to a direct current power supply, the microbial fuel cell module includes a microbial fuel cell and an aeration system, the aeration system aerates the cathode of the microbial fuel cell through an air pump, and the electricity generated by the microbial fuel cell module is recycled to the electrocatalytic membrane filtration module.

2. The electrocatalytic membrane filtration-microbial fuel cell coupling system according to claim 1, characterized in that: The pretreatment module is used to remove large particle impurities in wastewater; Electrocatalytic membrane filtration modules are suitable for removing calcium and magnesium hardness.

3. The electrocatalytic membrane filtration-microbial fuel cell coupling system according to claim 1, characterized in that: The cathode of the electrocatalytic membrane filtration module includes an insulating frame, a conductive filter membrane, a conductive coating, and a water pump; the insulating frame and the conductive filter membrane constitute a flat box-shaped body, the two sides of the box-shaped body with the largest area are the conductive filter membrane, the surrounding of the conductive filter membrane is supported and connected by the insulating frame, the box-shaped body has a reserved water outlet, and the water outlet is connected to the water pump through a pipe; the conductive coating is arranged on the two outer sides of the box-shaped body, which is a container with micropores on the surface, and the container contains fillers with electrocatalytic and adsorption properties.

4. The electrocatalytic membrane filtration-microbial fuel cell coupling system according to claim 3, characterized in that: The insulating frame of the reserved water outlet is made of plastic, preferably a rectangular or cylindrical acrylic plate frame; the conductive filter membrane is carbon fiber cloth, carbon fiber cloth coated with polyvinylidene fluoride PVDF or carbon felt; the conductive coating is detachable and can be movably and tightly installed on the outside of the insulating frame; the filler in the conductive coating is activated carbon particles loaded with cobalt or cerium or other conductive granular adsorption materials with electrocatalytic oxidation-reduction properties.

5. The electrocatalytic membrane filtration-microbial fuel cell coupling system according to claim 1, characterized in that: The microbial fuel cell is a double-chamber air cathode microbial fuel cell; the upper part is an anode chamber, water enters from the bottom of the anode chamber, and the upper part is a cathode chamber.

6. The electrocatalytic membrane filtration-microbial fuel cell coupling system according to claim 1, characterized in that: The anode chamber of the microbial fuel cell is filled with an activated carbon particle layer mainly loaded with Shewanella; the cathode chamber of the microbial fuel cell is filled with activated carbon particles loaded with cobalt and cerium to catalyze the reduction of organic pollutants to produce hydrogen peroxide to achieve further degradation of organic matter.

7. The electrocatalytic membrane filtration-microbial fuel cell coupling system according to claim 1, characterized in that: The electrocatalytic membrane filtration module and the microbial fuel cell module use the same activated carbon particles loaded with cobalt and cerium. The CoCe / AC preparation process is as follows: a certain amount of Co(NO3)2 and Ce(NO3)2 are added to an appropriate amount of deionized water, and then a nitrogen source is added and stirred to obtain a homogeneous solution, wherein the mass fraction of the nitrogen source in the homogeneous solution is 2 to 3 wt %. An appropriate amount of water-washed activated carbon is mixed and ultrasonically treated by an equal volume immersion method, and then dried in a 75 to 85°C forced air drying oven overnight; the dried particles are further sintered at high temperature in a muffle furnace.

8. The electrocatalytic membrane filtration-microbial fuel cell coupling system according to claim 7, characterized in that: The mass ratio of cobalt to cerium used in the CoCe / AC is 0.15:1-0.3:1; the immersion mixing and ultrasonic treatment time is 30-60 minutes; urea or melamine is used as a nitrogen source during the preparation of CoCe / AC; the high-temperature sintering temperature is 400-550°C and the time is 2-3 hours.

9. Application of an electrocatalytic membrane filtration-microbial fuel cell coupling system according to any one of claims 1 to 8, characterized in that: It is applied in the treatment of oil and gas field wastewater, specifically as follows: the wastewater enters the pretreatment module to remove large particles of waste; then it enters the electrocatalytic membrane filtration module, and the water in the box-shaped body of the insulating frame is pumped out by a water pump, forming a negative pressure in the box-shaped body of the insulating frame, so that the wastewater flows through the conductive layer and the conductive filter membrane. On the one hand, it can utilize the electroprecipitation active technology and the capacitive deionization technology to effectively remove the mineral salts of calcium and magnesium ions in the oil and gas field wastewater; on the other hand, it can achieve the removal of suspended matter in the oil and gas field wastewater and the structural destruction and toxicity reduction of large molecular organic matter through physical interception, electrosorption and electrocatalysis technology; finally, it enters the microbial fuel cell module to treat the primary wastewater treated by the electrocatalytic membrane filtration module. The MFC can effectively remove the COD in the wastewater to meet the treatment standards.

10. The use according to claim 9, characterized in that: The voltage of the DC power supply is 0.5-1.0V; the area of ​​the conductive filter membrane is 0.1-0.3m3; the thickness of the conductive layer is 1.5-2.5cm; the wastewater flux of the electrocatalytic membrane filter module is 200-300L·m - 3 · h -1 .

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