Device and method for enriching denitrifying anaerobic methane oxidation microorganisms by using bubble-free aeration conducting film

Abstract

The invention provides a device and a method for enriching denitrifying anaerobic methane oxidation microorganisms by utilizing a bubble-free aeration conducting film, and belongs to the technical field of environmental engineering. The device comprises an aeration membrane reactor, and the aeration membrane reactor comprises a shell, a water bath layer, an upper flange and a lower flange; an air inlet and an air outlet are inserted in the upper flange; an aeration membrane with conductivity is arranged in the shell; the end, located on the outer side of the shell, of the gas inlet is connected with a methane gas cylinder through a pipeline, and a gas pressure maintaining valve and a first one-way circulation device are sequentially arranged on the pipeline between the methane gas cylinder and the gas inlet. And a water supply container which is connected with the circulating liquid inlet and is used for providing an inoculum of DAMO bacteria and a liquid culture medium containing nitrogen oxide for the reactor is arranged outside the shell. According to the device and the method disclosed by the invention, the growth and the metabolism rate of DAMO microorganisms can be remarkably promoted through multiple intensifying of bubble-free aeration, biological retention, electroactivity and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental engineering, and in particular relates to a device and a method for enriching denitrifying anaerobic methane oxidizing microorganisms by utilizing a bubble-free aeration conductive membrane. Background Art Methane (CH 4 ) is a powerful greenhouse gas that contributes about 22% to global warming, second only to carbon dioxide. The methane oxidation process converts methane into carbon dioxide through microbial action and is of great significance in controlling global climate change. It is estimated that about 90% of the methane produced in marine sediments is oxidized through anaerobic oxidation processes. Continuous or intermittent flooding conditions in freshwater wetlands, paddy fields, inland aquatic ecosystems and coastal wetlands can also provide an oxygen-deficient environment for the anaerobic oxidation of methane (AOM) to occur. Anaerobic methanotrophs can combine AOM with various electron acceptors, such as nitrite (NO 2 − ), nitrate (NO 3 − ), metal oxides (Fe (III), Mn (IV) and AS (V)), sulfates (SO 4 2− ) and humus. The reaction with methane as electron donor and nitrite or nitrate as electron acceptor is called denitrifying anaerobic methane oxidation (DAMO). DAMO Archaea Candidatus 'Methanoperedens nitroreducens ( M. nitroreducens ) uses methane as an electron donor to reduce nitrate to produce nitrite, and DAMO bacteria uses methane as an electron donor to reduce nitrite to produce nitrogen gas.

[0002] CH 4 +4NO 3 - →CO 2 +4NO 2 - +2H 2 O(1) 3CH 4 +8NO 2 - +8H + →3CO 2 +4N 2 +10H 2 O(2) Greenhouse gas release and the need for an external carbon source for denitrification are two major problems faced by urban sewage treatment plants. The DAMO process has the dual effects of reducing nitrogen pollution and greenhouse gas emissions. Combining the DAMO process with existing sewage treatment technology has the dual effects of denitrification and carbon reduction, providing a new idea for nitrogen pollution control and greenhouse gas emission reduction.

[0003] Although DAMO bacteria are widely distributed in the natural environment, DAMO microorganisms grow very slowly, with a generation time of more than 4 weeks. Therefore, it is urgent to solve the problem of slow growth and low metabolic rate of denitrifying anaerobic methane oxidizing microorganisms. Summary of the invention

[0004] The purpose of the present invention is to solve the problem of slow growth and low metabolic rate of denitrifying anaerobic methane oxidizing microorganisms. Bubbleless aeration, electrical conductivity and high surface area of ​​activated carbon are combined, and the conductive bubbleless aeration membrane is placed in a bioreactor containing an inoculum containing DAMO bacteria and a liquid culture medium containing nitrate or nitrite. The aeration membrane is connected to the methane standard gas, and the microorganisms attach to the aeration membrane filaments or the surface conductive granular activated carbon and grow rapidly. The electron donor methane is supplied through the membrane pores without bubbles, and the electron acceptor nitrate or nitrite is dissolved in the solution and utilized by contacting with the microorganisms.

[0005] The present invention provides a device for enriching denitrifying anaerobic methane oxidizing bacteria, comprising: An aerated membrane reactor comprises a shell, a water bath layer arranged outside the shell, an upper flange arranged at the top of the shell and a lower flange arranged at the bottom of the shell; an air inlet and an air outlet are inserted on the upper flange; a circulating liquid inlet and a water bath layer inlet are arranged at the lower part of the shell, and a circulating liquid outlet and a water bath layer outlet are arranged at the upper part of the shell; an aeration membrane is arranged inside the shell, and the aeration membrane is a conductive aeration membrane, the upper end of the aeration membrane is open, the lower end is closed, and the upper end opening is connected to the air inlet; a liquid sealing mechanism is connected to the end of the air outlet located outside the shell; the end of the air inlet located outside the shell is connected to a methane gas cylinder through a pipeline, and a gas pressure regulating valve and a first one-way flow device are successively arranged on the pipeline between the methane gas cylinder and the air inlet; a water bath pot connected to the water bath layer inlet and the water bath layer outlet is arranged outside the shell; a water supply container connected to the circulating liquid inlet for providing the reactor with an inoculum of DAMO bacteria and a liquid culture medium containing nitrogen oxides is arranged outside the shell.

[0006] Furthermore, the aeration membrane with conductivity includes an aeration membrane with a conductive material loaded on the surface, or the membrane filaments of the aeration membrane doped with a conductive material; Preferably, the conductive material is activated carbon material, activated carbon, manganese particles, graphene, carbon fiber; More preferably, the conductive material is an activated carbon material.

[0007] Furthermore, the membrane filaments of the aeration membrane are doped with conductive materials, and bioelectrochemical reactors are added to the top and tail of the aeration membrane.

[0008] Furthermore, a first one-way flow device and a gas pressure regulating valve are used to control the partial pressure of the gas phase to be below the bubble point; Preferably, the methane supply pressure is controlled at 0.05~0.8Mpa.

[0009] Furthermore, a stirring magnet is provided at the bottom of the shell, and a magnetic stirrer for driving the stirring magnet to rotate is provided outside the shell; The upper flange is provided with a pH electrode for detecting the pH of the solution in the reactor and a temperature electrode for detecting the temperature of the solution in the reactor; Preferably, the end of the pH electrode located outside the shell is connected to a pH electrode digital display; the end of the temperature electrode located outside the shell is connected to a temperature electrode digital display.

[0010] Furthermore, the gas outlet is inserted into the liquid surface of the liquid sealing mechanism through a pipeline, and a second one-way flow device is provided on the pipeline; The temperature of water in the water bath layer is controlled at 10~50℃; The circulating liquid inlet and the circulating liquid outlet are connected through a pipeline, and a circulating pump is arranged on the pipeline.

[0011] Furthermore, the water supply container provides the reactor with an inoculum of DAMO bacteria and a liquid culture medium containing nitrogen oxides; preferably, the DAMO bacteria include DAMO bacteria and DAMO archaea. The present invention also provides a method for enriching denitrifying anaerobic methane oxidizing microorganisms using any of the above-mentioned devices.

[0012] Further, the method comprises: The water supply container is filled with an inoculum containing DAMO bacteria and a liquid culture medium containing nitrate or nitrite, which is fed into the shell from the circulating liquid inlet through a water inlet pump; a methane gas cylinder provides methane gas, which is fed into the shell from the gas inlet through a gas pressure regulating valve and a first one-way flow device; a water bath pot provides constant temperature water, which enters the interlayer of the reactor from the water bath layer inlet, and returns to the water bath pot through the water bath layer outlet; the air outlet is connected to a liquid sealing mechanism through a second one-way flow device; When a reaction occurs in the aerated membrane reactor, a conductive aeration membrane is used to maintain the gas phase partial pressure below the bubble point, and bubble-free aeration is performed in the membrane bioreactor. Nitrite nitrogen is reduced using gaseous methane as an electron donor and converted into nitrogen and carbon dioxide for discharge. At the same time, microbial DAMO bacteria are enriched on the aeration membrane and grow to form a biofilm, so that the gas transfer in the aerated membrane reactor is within the membrane.

[0013] Furthermore, during the enrichment culture process, the nutrient solution was added separately, and the frequency of addition was 3 to 4 times per month; During the enrichment culture, the pH was maintained at 6.0-9.0; The enrichment device is operated in an anaerobic environment; preferably, the anaerobic environment has a dissolved oxygen content of less than 0.20 mg / L.

[0014] The present invention has the following advantages: The device for enriching denitrifying anaerobic methane oxidizing microorganisms using a bubble-free aerated conductive membrane proposed by the present invention includes an aerated membrane reactor, which is composed of a shell, an upper flange, a lower flange, etc.; an air inlet and an air outlet are inserted on the upper flange; an aeration membrane with conductivity is arranged in the shell, the upper end of the aeration membrane is open, the lower end is closed, and the upper end opening is connected to the air inlet. The end of the air outlet located on the outside of the shell is connected to a liquid sealing mechanism to provide a guarantee for maintaining an anaerobic environment. The end of the air inlet located on the outside of the shell is connected to a methane gas cylinder, and a gas pressure regulating valve and a first one-way flow device are successively arranged between the methane gas cylinder and the air inlet to control the bubble-free aeration into the reactor. A water supply container is arranged outside the shell to provide the reactor with an inoculum of DAMO bacteria and a liquid culture medium containing nitrogen oxides. The water bath provides constant temperature water to ensure that the reaction is carried out under constant temperature conditions. The present invention proposes a method for enriching denitrifying anaerobic methane oxidizing microorganisms using a bubbleless aerated conductive membrane. The conductive aerated membrane is placed in a bioreactor containing an inoculum containing DAMO bacteria and a liquid culture medium containing nitrate or nitrite; the aeration membrane is in communication with the methane standard gas, and when the gas phase partial pressure is maintained below the bubble point through the gas pressure regulating valve and the first one-way flow device, bubbleless aeration can be ensured in the membrane bioreactor; when a reaction occurs in the reactor, methane is used as an electron donor to reduce nitrite nitrogen, which is converted into nitrogen and carbon dioxide and discharged. At the same time, microorganisms are enriched on the aeration membrane and grow to form a layer of biofilm, realizing solid-liquid separation, which can effectively reduce the loss of microorganisms; and the gas transfer in the aerated membrane bioreactor can be placed inside the membrane system, which increases the contact time between the gas phase and the liquid phase, thereby promoting the growth and metabolic rate of DAMO microorganisms. In addition, DAMO archaea have the ability to transfer extracellular electrons, and the bubbleless aerated conductive membrane can further enhance the electron transfer process of the DAMO biological system. It can be seen that the method of the present invention can significantly promote the growth and metabolic rate of DAMO microorganisms through multiple enhancements such as bubble-free aeration, biological retention and electroactivity. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0015] Figure 1 A schematic diagram of the structure of the device provided by the present invention; Figure 2 The test results obtained by the test examples of the present invention; in, Figure 1 Description of the accompanying drawings: Shell 1, aeration membrane 10, air inlet 11, air outlet 12, pH electrode 13, temperature electrode 14, water bath layer 110, water bath layer water inlet 111, water bath layer water outlet 112, upper flange 121, lower flange 122, circulating liquid inlet 131, circulating liquid outlet 132, circulating pump 133, magnetic stirrer 140, stirring magnet 141, methane gas cylinder 20, gas pressure regulating valve 21, first one-way flow device 22, liquid sealing mechanism 30, second one-way flow device 31, water supply container 40, water inlet pump 41, water bath pot 50. DETAILED DESCRIPTION

[0016] 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. In the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0017] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

[0018] The embodiment of the present invention provides a device for enriching denitrifying anaerobic methane oxidizing bacteria, comprising: The aerated membrane reactor comprises a shell 1, a water bath layer 110 arranged outside the shell 1, an upper flange 121 arranged at the top of the shell 1 and a lower flange 122 arranged at the bottom of the shell 1; the upper flange 121 is provided with an air inlet 11 and an air outlet 12; the lower part of the shell 1 is provided with a circulating liquid inlet 131 and a water bath layer inlet 111, and the upper part of the shell 1 is provided with a circulating liquid outlet 132 and a water bath layer outlet 112; the shell 1 is provided with an aeration membrane 10, the aeration membrane 10 is an aeration membrane 10 with conductivity, the upper end of the aeration membrane 10 is open, the lower end is closed, and the upper end opening is connected to the The air inlet 11 is connected; the end of the air outlet 12 located on the outside of the shell 1 is connected to a liquid sealing mechanism 30; the end of the air inlet 11 located on the outside of the shell 1 is connected to the methane gas cylinder 20 through a pipeline, and a gas pressure regulating valve 21 and a first one-way flow device 22 are successively provided on the pipeline between the methane gas cylinder 20 and the air inlet 11; a water bath pot 50 connected to the water inlet 111 and the water outlet 112 of the water bath layer is provided outside the shell 1; a water supply container 40 connected to the circulating liquid inlet 131 for providing the reactor with an inoculum of DAMO bacteria and a liquid culture medium containing nitrogen oxides is provided outside the shell 1.

[0019] In the embodiment of the present invention, the inventors of the present application have found through research that, in addition to its own characteristics, the most important influencing factor for the slow growth of DAMO microorganisms is the culture conditions. Methane supply is a limiting factor for the growth of DAMO microorganisms. The use of bubble-free aeration can ensure sufficient supply of electron donor methane. Another influencing factor that causes the slow start-up of the DAMO system is the loss of biomass. The discharge of water or mud during the culture process is not conducive to the maintenance of the system's biomass. Bubble-free aeration can provide attachment space for the growth of organisms, which is beneficial to maintaining the biomass of the reaction system. In addition, the aeration membrane with conductivity and the conductive material can transfer electrons to microorganisms, promote microbial metabolism, and increase the biodegradation rate, or add a bioelectrochemical reactor at the top and tail of the aeration membrane, and provide voltage to the aeration membrane assembly to accelerate electron transfer, and indirectly or directly provide electron flow to microorganisms. An external auxiliary voltage can also promote the growth and metabolism of the DAMO biological system. Specifically, compared with traditional bubble aeration, bubbleless aeration has the following advantages: First, the way gas enters the biofilm during bubbleless aeration is direct molecular diffusion, which makes the efficiency of gas mass transfer much higher, and can be 100% utilized by organisms, so the activity of the biofilm will be higher. Therefore, the solubility of gas is no longer a limiting factor in determining the growth and metabolism of microorganisms in a bubbleless aeration bioreactor. Secondly, during bubble aeration, the gas will produce friction with the biofilm during the rising process, causing the biofilm to fall off the carrier, while bubbleless aeration will not have this phenomenon at all, so the biofilm is more firmly attached and is not easy to fall off. Thirdly, the bubbleless aeration reactor is more flexible, because the gas phase and the liquid phase are separated in the process of bubbleless aeration, and the gas supply can be adjusted by changing the pressure in the membrane. In addition, the energy consumption of bubbleless aeration is much lower than that of bubble-type gas supply, which is more economical.

[0020] In an embodiment of the present invention, the first one-way flow device 22 and the gas pressure regulating valve 21 are used to control the gas phase partial pressure below the bubble point. The first one-way flow device 22 is used to control the flow rate, and the gas pressure regulating valve 21 is used to control the pressure. In an embodiment of the present invention, the methane supply pressure is controlled at 0.05-0.8Mpa, and the methane aeration can be performed in a bubbleless aeration mode.

[0021] In one embodiment of the present invention, a stirring magnet 141 is provided at the bottom of the housing 1, and a magnetic stirrer 140 is provided outside the housing for driving the stirring magnet to rotate. The stirring rate of the stirring magnet 141 is controlled at 100-1200 rpm.

[0022] In one embodiment of the present invention, the upper flange 24 is disposed at the top of the housing 1 and can be fixed to the top of the housing 1 by screws; the lower flange 25 is disposed at the bottom of the housing 1 and can be fixed to the bottom of the housing 1 by screws. A magnetic stirrer 140 is disposed at the lower end of the lower flange, and stirring is achieved by controlling the stirring magnet 141.

[0023] In one embodiment of the present invention, a pH electrode 13 for detecting the pH of the solution in the reactor and a temperature electrode 14 for detecting the temperature of the solution in the reactor are inserted into the upper flange 24 .

[0024] In one embodiment of the present invention, the end of the pH electrode 13 located outside the shell is connected to a pH electrode digital display; the end of the temperature electrode 14 located outside the shell is connected to a temperature electrode digital display. The temperature and pH of the solution inside the reactor are detected in real time by the pH electrode 13 and the temperature electrode 14, and the data are displayed by the pH electrode digital display and the temperature electrode digital display.

[0025] In one embodiment of the present invention, the gas outlet 12 is inserted into the liquid surface of the liquid sealing mechanism 5 through a pipeline, and the pipeline is provided with a second one-way flow device 31. The liquid sealing mechanism 5 can relieve the pressure in the enrichment device and provide a guarantee for maintaining an oxygen-free environment. The liquid sealing mechanism 5 includes a gas washing bottle filled with water.

[0026] In one embodiment of the present invention, the temperature of the water in the water bath layer 110 is controlled at 10-50°C. Water enters the water bath layer 110 from the water bath pot 50 through the water bath layer water inlet 111, and returns to the water bath pot 50 from the water bath layer water outlet 112, which plays a role in heat preservation and constant temperature. The temperature of the water bath layer 110 is controlled at 10-50°C, and then the internal temperature of the denitrification anaerobic methane oxidation enrichment device is controlled at 15-45°C; preferably 35°C.

[0027] In one embodiment of the present invention, the circulating liquid inlet 131 and the circulating liquid outlet 132 are connected by a pipeline, and the pipeline is provided with a circulating pump 133. The circulating pump can increase the material circulation inside the reactor, so that the inoculum can be more fully attached to the membrane filaments. Furthermore, the inoculum for providing the reactor with DAMO bacteria and the liquid culture medium containing nitrogen oxides enter the shell to become the circulating liquid, and the circulation rate of the circulating liquid is 0.05~0.5 L / min.

[0028] In one embodiment of the present invention, the water supply container 40 provides the reactor with an inoculum of DAMO bacteria and a liquid culture medium containing nitrogen oxides. Preferably, the DAMO bacteria include DAMO bacteria and DAMO archaea.

[0029] Furthermore, the water supply container 40 can also provide denitrifying bacteria for the reactor. The denitrifying bacteria include but are not limited to Ignavibacterium SP, HyphomicrobiumSP, Rhizobiaceae SP, Alicycliphilus SP.

[0030] Furthermore, the composition of the liquid culture medium includes: mineral matrix: KHCO 3 0.1-0.3mg / L, KH 2 PO 4 0.2-0.4mg / L,CaCl 2 0.2-0.4mg / L, MgSO 4 0.1-0.3mg / L; Acidic trace elements: FeSO 4 7H 2 O1.5~3.0mg / L, ZnSO 4 7H 2 O 0.05~0.15mg / L, CoCl 2 6H 2 O 0.1~0.2mg / L, MnCl 2 ·4H 2 O0.3~1.0mg / L, NiCl 2 ·4H 2 O 0.2~0.5mg / L, CuSO 4 0.05~0.15mg / L, H 3 BO 3 0.005~0.02mg / L; Alkaline trace elements: SeO 2 0.05~0.1mg / L, Na 2 WO 2 ·2H 2 O 0.05~0.1mg / L, Na 2 MoO 4 0.2~0.3mg / L. In an embodiment of the present invention, the liquid culture medium enters the shell of the aerated membrane reactor from the circulating liquid inlet, forms a circulating liquid after passing through the aeration membrane, is discharged from the circulating liquid outlet, passes through the circulating pump, and enters the shell again from the circulating liquid inlet for utilization.

[0031] In one embodiment of the present invention, in the aerated membrane reactor, DAMO archaea ( M. nitroreducens ) accounted for 0.1~99% of the total bacterial population, with an abundance of 20-450 mg VSS / L; DAMO bacteria ( M. oxyfera ) accounted for 0.1-99% of the total bacterial count, and the abundance was 15-380 mg VSS / L; DAMO Archaea in circulating fluid ( M. nitroreducens) accounted for 0.1~99% of the total bacterial population and the abundance was 2.5×10 2 —5.2×10 14 copies L -1 DAMO bacteria ( M. oxyfera ) accounted for 0.1~99% of the total bacterial population and the abundance was 6.8×10 2 —1.0×10 14 copies L -1 .

[0032] Furthermore, during the enrichment culture process, the nutrient solution is added separately, and the frequency of addition is 3 to 4 times a month. Regular addition of nutrient solution reduces the fluctuation of the microbial environment and provides a high-quality environment for the growth of denitrifying anaerobic methane oxidizing microorganisms.

[0033] Furthermore, the enrichment device is operated in an anaerobic environment; preferably, the anaerobic environment has a dissolved oxygen content lower than 0.20 mg / L.

[0034] In one embodiment of the present invention, the membrane type used in the aeration membrane 10 is a microporous membrane or a dense membrane, and the membrane material is polyethylene, polyvinylidene fluoride or polytetrafluoroethylene. Compared with other membrane materials, its rough surface is more conducive to the attachment of dry microorganisms. As a hydrophobic membrane, oxygen can diffuse to the outer wall of the membrane only through the membrane pores during transmission. Compared with the hydrophilic microporous membrane in which oxygen molecules are transmitted in the micropores in the form of dissolved oxygen, the resistance to oxygen transmission is smaller.

[0035] In one embodiment of the present invention, the filling ratio of the aeration membrane 10 to the volume ratio of the shell 1 is 5-70%.

[0036] In one embodiment of the present invention, the diameter of the membrane filaments of the aeration membrane 10 is generally selected between 0.1 mm and 2.0 mm. Thinner membrane filaments can provide a higher specific surface area, which is beneficial to the transmission of oxygen. The number of membrane filaments is 10-50, and the membrane filament spacing is 5mm-50mm.

[0037] In a preferred embodiment of the present invention, the conductive aeration membrane includes an aeration membrane with a conductive material loaded on its surface, or membrane filaments of the aeration membrane are doped with a conductive material.

[0038] Preferably, the conductive material is activated carbon material, activated carbon, manganese particles, graphene, or carbon fiber.

[0039] More preferably, the conductive material is an activated carbon material. The activated carbon is made of organic raw materials (coal, wood, etc.), the activated carbon particle size is 8-16 mesh, the strength is 90-95%, the particle density is 0.35-0.55g / cm³, and the activated carbon pore size is 10-50nm. Preferably, the membrane fiber surface area loading ratio on the aeration membrane is 0.5-30%.

[0040] In the embodiment of the present invention, the conductive aeration membrane can realize two conductive modes: For aeration membranes loaded with conductive materials, the conductive materials are compounded on the surface of the aeration membranes; or for membrane filaments of the aeration membranes doped with conductive materials, bio-electrochemical reactors are added to the top and tail of the aeration membranes to provide voltage for the aeration membrane components.

[0041] Specifically, in the embodiment of the present invention, the conductive aeration membrane realizes two conductive modes: First, during the aeration membrane production process, activated carbon and other materials that promote microbial electron transfer are added to the aeration membrane surface. Activated carbon with rich porous structure is used as a methane adsorption material. Activated carbon with a large specific surface area can be used as a container for methane adsorption, continuously reducing the content of methane in the reactor headspace, increasing the availability of methane in the enrichment device, and through the redox functional part of the activated carbon, the ideal inherent conductivity and electron capacity can promote the transfer of electrons from methane oxidation by DAMO microorganisms; Secondly, add bio-electrochemical reactors at the top and tail of the aeration membrane to provide voltage for the aeration membrane assembly and accelerate electron transfer, providing electron flow to microorganisms indirectly or directly. The gas enters the cavity of the aeration membrane and then seeps out of the membrane wall, with the purpose of prompting the biofilm to quickly attach and fix on the surface of the aeration membrane. With the membrane filaments as carriers and improving the gas mass transfer characteristics, the enrichment of DAMO bacteria can be quickly improved.

[0042] Furthermore, the cathode and anode of the bio-electrochemical reaction container are 5-20 cm apart. Furthermore, the cathode and anode of the bio-electrochemical reaction container are independently selected from mesh or columnar stainless steel, carbon fiber, carbon felt, carbon cloth, carbon rod and other materials. The mesh or columnar cathode / cathode can be folded or bent to increase the surface area; the anode potential is controlled within the range of 0-2000mV to start the system and improve the enrichment efficiency of the electrogenic microorganisms.

[0043] The embodiment of the present invention also proposes a method for enriching denitrifying anaerobic methane oxidizing microorganisms using the above-mentioned device for enriching denitrifying anaerobic methane oxidizing bacteria.

[0044] In one embodiment of the present invention, the method comprises: The water supply container 40 is filled with an inoculum containing DAMO bacteria and a liquid culture medium containing nitrate or nitrite, which is fed into the housing 1 through the circulating liquid inlet 131 by the water inlet pump 41; the methane gas cylinder 20 provides methane gas, which is fed into the housing 1 through the gas pressure regulating valve 21 and the first one-way flow device 22 through the air inlet 11; the water bath 50 provides constant temperature water, which enters the interlayer of the reactor through the water bath layer water inlet 111 and returns to the water bath 50 through the water bath layer water outlet 112; the air outlet 12 is connected to the liquid sealing mechanism 30 through the second one-way flow device 31; When a reaction occurs in the aerated membrane reactor, methane is used as an electron donor to reduce nitrite nitrogen, which is converted into nitrogen and carbon dioxide for discharge. At the same time, microorganisms are enriched on the aeration membrane 10 and grow to form a biofilm, thereby achieving solid-liquid separation and effectively reducing the loss of microorganisms. By utilizing the conductive aeration membrane 10, when the gas phase partial pressure is maintained below the bubble point, bubble-free aeration can be performed in the membrane bioreactor, so that the gas transfer in the membrane aerated bioreactor is within the membrane system. Test Example 1 Testing the effect of enriching microorganisms by the device of the present invention Before the operation of the reactor, take 1L of the prepared liquid culture medium and remove the dissolved oxygen in the liquid culture medium under 99% nitrogen blowing to keep the liquid culture medium in an anoxic environment. Use 1mmol / L NaOH to adjust the pH of the liquid culture medium to about 7.5. Under the control of the methane gas bus (methane supply pressure is controlled at 0.5 Mpa) and the first one-way flow device (0.01~0.5L / min), 95% of the methane and 5% of the carbon dioxide in the gas cylinder are continuously sent to the reactor through the aeration membrane in a bubble-free aeration manner. The composition of the liquid culture medium includes: Mineral matrix: KHCO 3 0.2 mg / L, KH 2 PO 4 0.3mg / L,CaCl 2 0.3mg / L, MgSO 4 0.2mg / L; Acidic trace elements: FeSO 4 7H 2 O 2.0mg / L, ZnSO 4 7H 2 O 0.1mg / L, CoCl 2 6H 2 O 0.15 mg / L, MnCl 2 ·4H 2 O0.5mg / L, NiCl 2 ·4H 2 O 0.4mg / L, CuSO 4 0.1mg / L, H 3 BO 3 0.01mg / L; Alkaline trace elements: SeO 2 0.08mg / L, Na 2 WO 2 ·2H 2 O 0.08mg / L, Na 2 MoO 4 0.25mg / L. Using ultraviolet ion chromatography, the concentration of nitrite nitrogen in the reactor was tested once every two days. The concentration of nitrite nitrogen in the liquid culture medium was fixed at 30 mg-N / L. When the concentration of nitrite nitrogen in the reactor was lower than 5 mg-N / L, fresh liquid culture medium should be replaced in time. The reactor was operated at a constant temperature of 35°C.

[0045] This batch of experiments lasted for two weeks, during which we explored the effects of different conductive modes (conductive mode 1 is adding activated carbon to the surface of the aeration membrane; conductive mode 2 is adding a bio-electrochemical reactor at the top and tail of the aeration membrane to provide voltage for the aeration membrane) on the metabolic activity of microorganisms. The experimental results are as follows Figure 2 shown. Depend on Figure 2 It can be seen that compared with the control group, the two different power-on methods can promote the growth of bacterial metabolic activity in the reactor: conductive mode 1 can increase the bacterial metabolic activity by about 75%, and conductive mode 2 can increase the bacterial metabolic activity by about 100%. It can be seen that the growth of bacterial metabolic activity can be greatly improved by power-on.

[0046] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for enriching denitrifying anaerobic methane oxidizing bacteria, characterized in that: include: An aerated membrane reactor comprises a shell, a water bath layer arranged outside the shell, an upper flange arranged at the top of the shell and a lower flange arranged at the bottom of the shell; an air inlet and an air outlet are inserted on the upper flange; a circulating liquid inlet and a water bath layer inlet are arranged at the lower part of the shell, and a circulating liquid outlet and a water bath layer outlet are arranged at the upper part of the shell; an aeration membrane is arranged inside the shell, and the aeration membrane is a conductive aeration membrane, the upper end of the aeration membrane is open, the lower end is closed, and the upper end opening is connected to the air inlet; a liquid sealing mechanism is connected to the end of the air outlet located outside the shell; the end of the air inlet located outside the shell is connected to a methane gas cylinder through a pipeline, and a gas pressure regulating valve and a first one-way flow device are successively arranged on the pipeline between the methane gas cylinder and the air inlet; a water bath pot connected to the water bath layer inlet and the water bath layer outlet is arranged outside the shell; a water supply container connected to the circulating liquid inlet for providing the reactor with an inoculum of DAMO bacteria and a liquid culture medium containing nitrogen oxides is arranged outside the shell.

2. The device according to claim 1, characterized in that The aeration membrane with conductivity includes an aeration membrane with a conductive material loaded on the surface, or the membrane filaments of the aeration membrane doped with a conductive material; Preferably, the conductive material is activated carbon material, activated carbon, manganese particles, graphene, carbon fiber; More preferably, the conductive material is an activated carbon material.

3. The device according to claim 2, characterized in that The membrane filaments of the aeration membrane are doped with conductive materials, and bio-electrochemical reactors are added to the top and tail of the aeration membrane.

4. The device according to claim 1, characterized in that A first one-way flow device and a gas pressure regulating valve are used to control the gas phase partial pressure below the bubble point; Preferably, the methane supply pressure is controlled at 0.05~0.8Mpa.

5. The device according to claim 1, characterized in that A stirring magnet is provided at the bottom of the shell, and a magnetic stirrer is provided outside the shell for driving the stirring magnet to rotate; The upper flange is provided with a pH electrode for detecting the pH of the solution in the reactor and a temperature electrode for detecting the temperature of the solution in the reactor; Preferably, the end of the pH electrode located outside the shell is connected to a pH electrode digital display; the end of the temperature electrode located outside the shell is connected to a temperature electrode digital display.

6. The device according to claim 1, characterized in that The gas outlet is inserted into the liquid surface of the liquid sealing mechanism through a pipeline, and a second one-way flow device is provided on the pipeline; The temperature of water in the water bath layer is controlled at 10~50℃; The circulating liquid inlet and the circulating liquid outlet are connected through a pipeline, and a circulating pump is arranged on the pipeline.

7. The device according to claim 1, characterized in that The water supply container provides the reactor with an inoculum of DAMO bacteria and a liquid culture medium containing nitrogen oxides; preferably, the DAMO bacteria include DAMO bacteria and DAMO archaea.

8. A method for enriching denitrifying anaerobic methane oxidizing microorganisms using the device according to any one of claims 1 to 7.

9. The method according to claim 8, characterized in that The method comprises: The water supply container is filled with an inoculum containing DAMO bacteria and a liquid culture medium containing nitrate or nitrite, which is fed into the shell from the circulating liquid inlet through a water inlet pump; a methane gas cylinder provides methane gas, which is fed into the shell from the gas inlet through a gas pressure regulating valve and a first one-way flow device; a water bath pot provides constant temperature water, which enters the interlayer of the reactor from the water bath layer inlet, and returns to the water bath pot through the water bath layer outlet; the air outlet is connected to a liquid sealing mechanism through a second one-way flow device; When a reaction occurs in the aerated membrane reactor, a conductive aeration membrane is used to maintain the gas phase partial pressure below the bubble point, and bubble-free aeration is performed in the membrane bioreactor. Nitrite nitrogen is reduced using gaseous methane as an electron donor and converted into nitrogen and carbon dioxide for discharge. At the same time, microbial DAMO bacteria are enriched on the aeration membrane and grow to form a biofilm, so that the gas transfer in the aerated membrane reactor is within the membrane.

10. The method according to claim 9, characterized in that During the enrichment culture, the nutrient solution was added separately, and the frequency of addition was 3 to 4 times per month; During the enrichment culture, the pH was maintained at 6.0-9.0; The enrichment device is operated in an anaerobic environment; preferably, the anaerobic environment has a dissolved oxygen content of less than 0.20 mg / L.

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