An anaerobic membrane bioreactor and a method for treating wastewater and simultaneously recycling resources thereof

Abstract

The application discloses an anaerobic membrane bioreactor and a method for treating wastewater and recycling resources synchronously. The anaerobic membrane bioreactor comprises a power supply device and a reactor main body, the reactor main body is internally provided with a cathode and an anode, the cathode and the anode are connected with the power supply device respectively, the anode comprises a magnesium anode and a conductive membrane anode, the conductive membrane anode comprises at least one hollow porous filter element; the anaerobic membrane bioreactor comprises a triggering mechanism, and the triggering mechanism is used for switching the connection relationship between the power supply device and the anode between a first state and a second state. The anaerobic membrane bioreactor provided by the application is an integrated reactor main body, the conductive membrane and the magnesium electrode are used as double anodes, and the anaerobic membrane bioreactor can effectively realize the anti-fouling of the membrane and the recycling of carbon, nitrogen and phosphorus.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology and relates to an anaerobic membrane bioreactor and a method for treating wastewater and simultaneously recovering resources. Background Technology

[0002] In the context of sustainable development, wastewater treatment facilities must not only recycle renewable resources but also achieve carbon emission reduction. The difficulty of treating wastewater varies depending on its type. For example, livestock and poultry wastewater or urine, due to its very high concentrations of organic matter, nitrogen, and phosphorus, is more difficult to treat than municipal wastewater.

[0003] Anaerobic membrane bioreactors (AnMBRs) are highly efficient and low-carbon wastewater treatment technologies that integrate anaerobic processes with membrane separation, showing promising applications in sustainable water treatment. AnMBRs offer numerous advantages, including high effluent quality, small footprint, low energy demand, and high digestion efficiency. However, challenges such as membrane fouling and the inability to recover nitrogen and phosphorus significantly limit the large-scale application of AnMBRs in wastewater treatment. Addressing these issues can greatly improve their efficiency and expand their application scope.

[0004] Furthermore, biogas produced during anaerobic digestion plays a crucial role in the emerging renewable energy market. Optimizing biogas production and upgrading it to more effectively utilize this renewable energy source is a key direction for the future of anaerobic processes, thereby supporting the goal of sustainable wastewater development and treatment. However, in existing technologies, the biogas produced during anaerobic digestion contains 60%-70% methane (CH4) and 30%-40% carbon dioxide (CO2), which reduces its calorific value. Therefore, to make biogas an effective fuel source, it is necessary to increase the methane / CO2 ratio, i.e., to increase the purity of methane. For example, CN103508829A discloses a method for purifying methane from biogas, in which the raw biogas undergoes pretreatment, pressurization, and then adsorption purification through multiple adsorption towers connected in series, resulting in a significant increase in the purity of the obtained methane product. Obviously, this method of increasing methane purity increases equipment and production costs.

[0005] Furthermore, membrane fouling in anaerobic membrane bioreactors also affects wastewater treatment efficiency. Various methods for controlling membrane fouling have been reported, including biogas injection, backwashing, acid washing, and bacterial colony quenching. However, research on mitigating membrane fouling while treating wastewater is scarce.

[0006] CN110372091A discloses an anaerobic membrane bioreactor coupled with an anaerobic ammonia oxidation system and a municipal wastewater treatment process. The system includes an anaerobic membrane bioreactor, a partial nitrification reactor, and an anaerobic ammonia oxidation reactor. A first equalization tank is located between the anaerobic membrane bioreactor and the partial nitrification unit, and a second equalization tank is located between the partial nitrification unit and the anaerobic ammonia oxidation reactor. The effluent end of the anaerobic membrane bioreactor is connected to the first equalization tank, the liquid output end of the first equalization tank is connected to the inlet end of the partial nitrification unit, the effluent end of the partial nitrification unit is connected to the second equalization tank, and the effluent end of the second equalization tank is connected to the inlet end of the anaerobic ammonia oxidation reactor. This invention removes organic matter through the anaerobic membrane bioreactor and recovers the generated methane gas as an energy source. Then, it effectively removes nitrogen from wastewater through anaerobic ammonia oxidation autotrophic denitrification. However, this method treats municipal wastewater with relatively low organic matter concentrations. It is not suitable for treating livestock and poultry wastewater or urine, and it cannot remove phosphorus. Furthermore, the nitrogen removal method in this patent is biological, which has the disadvantage of requiring stringent conditions for the domestication and cultivation of microorganisms. Moreover, the anaerobic membrane bioreactor coupled with the anaerobic ammonia oxidation system is a long-process equipment with a complex structure and a large footprint.

[0007] CN113354083B discloses an apparatus and method for simultaneous recovery of struvite in anaerobic membrane biological wastewater treatment. The apparatus includes an anaerobic bioreactor, a membrane module reactor, and a power supply device. The anaerobic bioreactor is connected to the membrane module reactor, and the power supply device is electrically connected to the membrane module reactor. The membrane module reactor includes a shell, which comprises an anode plate, a cathode plate, a membrane module, and a pH probe. The anode plate and cathode plate are distributed on both sides of the membrane module, and the anode plate is a magnesium plate. In this invention, under the presence of an electric field, the electrode reaction can increase the solution pH, effectively inhibiting acidification, stimulating microorganisms, accelerating pollutant degradation, and increasing the surface charge of sludge, thus alleviating membrane fouling to some extent. Furthermore, using a magnesium plate as the anode plate can solve the problem of low nitrogen and phosphorus removal rates in anaerobic membrane bioreactors and convert them into usable struvite resources for recovery. However, firstly, this apparatus for simultaneous recovery of struvite in anaerobic membrane biological wastewater treatment is a split design, requiring a large area; secondly, the degree of membrane fouling mitigation is not high; and thirdly, its methane purity is low. Moreover, it does not take into account energy consumption and material consumption.

[0008] Therefore, providing an anaerobic membrane bioreactor capable of treating livestock and poultry breeding wastewater or urine sewage, effectively achieving membrane antifouling and carbon, nitrogen, and phosphorus recovery while reducing energy and material consumption, is a technical problem that urgently needs to be solved. Summary of the Invention

[0009] To address the aforementioned problems in the existing technology, the present invention aims to provide an anaerobic membrane bioreactor and a method for simultaneously treating wastewater and recovering resources.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides an anaerobic membrane bioreactor, the anaerobic membrane bioreactor comprising a power supply device and a reactor body, wherein a cathode and an anode are disposed within the reactor body, the cathode and the anode being respectively connected to the power supply device, the anode comprising a magnesium anode and a conductive membrane anode, the conductive membrane anode comprising at least one hollow porous filter element;

[0012] The anaerobic membrane bioreactor body also includes a triggering mechanism, which is used to switch the connection between the power supply device and the anode between a first state and a second state: in the first state, the power supply device is connected to the conductive membrane anode; in the second state, the power supply device is connected to the magnesium anode.

[0013] In one embodiment, the reactor body is further provided with an inlet and an outlet, the outlet being provided with an outlet pipe, one end of which is connected to the opening of the hollow porous filter element.

[0014] The anaerobic membrane bioreactor provided by this invention is an integrated device with a simple structure and small footprint. It uses a conductive membrane and a magnesium electrode as dual anodes. During operation, the conductive membrane and magnesium electrode switch anodes, effectively achieving membrane antifouling and the recovery of carbon, nitrogen, and phosphorus—a technical problem that urgently needs to be solved.

[0015] The working principle and advantages of the anaerobic membrane bioreactor of the present invention are as follows: When the power supply device provides voltage between the conductive membrane and the cathode, the anodic potential applied to the conductive membrane will enhance the electrochemical oxidation capacity of the microorganisms in the biofilm attached to the conductive membrane surface and the electron transfer between them and the electrode (conductive membrane), thereby degrading some of the organic matter in the filter cake layer on the conductive membrane surface, making the filter cake layer loose and porous, which is conducive to water passage and helps to alleviate membrane fouling; moreover, the release of magnesium ions will change the physicochemical properties of sludge, increase the sludge particle size, reduce the absolute value of sludge zeta potential, which is conducive to sludge aggregation, reduces sludge viscosity and adhesion between sludge and the conductive membrane surface, weakens the formation of gel layer, improves the structure of the filter cake layer on the membrane surface, and thus alleviates membrane fouling.

[0016] When the power supply provides voltage between the magnesium electrode and the cathode, magnesium acts as the anode, releasing magnesium ions, while the cathode undergoes a hydrogen evolution reaction to produce OH-. - This raises the pH near the cathode plate, creating an environment conducive to struvite deposition, and the magnesium anode produces Mg. 2+They will migrate to the vicinity of the cathode and combine with ammonia, nitrogen, and phosphate in the sewage flowing in from the inlet to form struvite. A large amount of struvite will precipitate on the cathode surface. The struvite can be recovered by replacing the cathode.

[0017] Furthermore, the magnesium ions released from the anode and the hydroxide ions released from the hydrogen evolution reaction at the cathode combine with carbon dioxide in the biogas produced by anaerobic microorganisms, capturing and fixing carbon. Since the main components of biogas are methane and carbon dioxide, this effectively reduces the proportion of carbon dioxide. The hydrogen produced during the hydrogen evolution reaction at the cathode can also be used as a raw material to promote methane production. The introduction of magnesium anode alters the microbial community structure, enhancing multiple methane production pathways and interspecies direct electron transport pathways within the system, thus increasing methane production. Therefore, the increased proportion of methane in the biogas, i.e., increased methane purity, is beneficial for energy recovery. Calculations show that using the generated methane as energy is far more efficient than the electrical energy input into the system. Moreover, the biogas methane collected in this invention has high purity, eliminating the need for post-treatment equipment to purify the biogas, which has significant advantages compared to existing technologies.

[0018] Furthermore, this invention uses a conductive film and a magnesium electrode as dual anodes, which allows the magnesium electrode plate to operate without always being under an external power supply, avoiding excessive release of magnesium, saving electrode plates, and reducing energy input. Simultaneously, this invention utilizes physicochemical precipitation to remove N and P, which is easier to operate compared to biological methods.

[0019] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0020] Preferably, the triggering mechanism is: an electrical control device is provided on the connection line between the power supply device and the anode, used to regulate the connection of the power supply device with the magnesium anode or with the conductive film anode; or,

[0021] Two switches are installed on the power supply device to control the opening and closing states of the line connected to the magnesium anode and the line connected to the conductive film anode, respectively.

[0022] In one implementation, the electrical control device is a relay.

[0023] Preferably, the reactor body is also equipped with a stirring device for stirring the sludge.

[0024] Preferably, the power supply device is a DC power supply.

[0025] Preferably, the reactor body is a cylindrical plexiglass reactor, which can provide good hydraulic conditions for the system and facilitate the full progress of the reaction.

[0026] Preferably, the reactor body is also equipped with a gas collection device. This gas collection device can recover gases such as methane.

[0027] Preferably, the magnesium anode and the conductive film anode are located on opposite sides of the cathode.

[0028] Preferably, the area of ​​the cathode is 1-8 times the area of ​​the magnesium anode, for example, it can be 1, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, or 8 times the area of ​​the magnesium anode. In the anaerobic membrane bioreactor of the present invention, struvite is deposited on the cathode, and the struvite can be recovered by removing the cathode. Under the above-defined conditions, a larger attachment area can be provided for the struvite, which is beneficial for its recovery.

[0029] Preferably, the magnesium anode is disposed opposite to the cathode.

[0030] In one embodiment, the plane facing the cathode from the magnesium anode is called A, and the projection of plane A onto the cathode is called B. A and B are the same size.

[0031] Preferably, the conductive film anode is disposed opposite to the cathode.

[0032] In one embodiment, the plane of the conductive film anode facing the cathode is C, and the projection of plane C onto the cathode is D, with C and D having the same size.

[0033] Preferably, the distance from the magnesium anode to the cathode is 'a' (cm), and the area of ​​the plane of the cathode facing the magnesium anode is 'S' (cm²). 2 And a / S is 1 / 10-1 / 60cm -1 For example, a / S could be 1 / 10 cm. -1 1 / 12cm -1 1 / 15cm -1 1 / 18cm -1 1 / 20cm -1 1 / 23cm -1 1 / 25cm -1 1 / 30cm -1 1 / 35cm -1 1 / 40cm -1 1 / 45cm -1 1 / 50cm -1 1 / 55cm -1or 1 / 60cm -1 If the distance from the magnesium anode to the cathode is too large, it will affect the migration of ions, thereby affecting the enrichment and deposition of struvite ions on the cathode surface; if the distance from the magnesium anode to the cathode is too small, it will affect the growth of struvite crystals.

[0034] This invention does not impose a specific limitation on the distance from the anode to the cathode of the conductive film; those skilled in the art can select an appropriate distance as needed.

[0035] Preferably, the cathode is made of a material capable of guano deposition, and preferably includes, but is not limited to, at least one of carbon materials, elemental metals, stainless steel, and conductive polymers.

[0036] Preferably, the carbon material includes at least one of graphite, activated carbon, graphene, carbon nanotubes, and carbon felt.

[0037] Preferably, the metallic element includes any one of copper, iron, nickel, chromium, platinum, gold, silver, cobalt, tin, or manganese.

[0038] It should be noted that the cathode in this invention is not limited to the materials listed above. Other cathode materials commonly used in the art that are not listed are also applicable to this invention.

[0039] Preferably, the magnesium anode is an electrode material with a magnesium content of more than 90%, preferably pure magnesium, AZ31 alloy or AZ91 alloy.

[0040] Preferably, one end of the hollow porous filter element is open, and multiple hollow porous filter elements are connected to each other for water outlet using a multi-channel diversion pipe.

[0041] In one embodiment, the opening of each porous filter element is connected to multiple pipes of a multi-channel diversion pipeline, and water is discharged through the outlet pipe.

[0042] In one embodiment, the hollow porous filter element includes: a fixing member with openings at both ends and a filter bag sealed at one end of the fixing member, the filter bag being formed by surrounding a porous conductive membrane.

[0043] Preferably, the porous conductive film is made of materials including, but not limited to, titanium, titanium alloys, carbon nanotubes, stainless steel, Ni-Cu alloys, Ni-Cr-Fe alloys, iron-aluminum alloys, Hastelloy B, Hastelloy C, or Hastelloy X. However, it is not limited to the types listed above; other commonly used materials in the art that are conductive and stable and not easily oxidized by electro-oxidation are also suitable for this invention.

[0044] Preferably, the pore size of the porous conductive film is less than or equal to 0.45 μm, for example, it can be 0.45 μm, 0.43 μm, 0.42 μm, 0.40 μm, 0.38 μm, 0.35 μm, 0.33 μm, 0.32 μm, 0.30 μm, 0.28 μm, 0.26 μm, 0.24 μm, 0.22 μm, 0.20 μm, 0.18 μm, 0.15 μm, 0.12 μm, 0.10 μm, 0.08 μm, 0.05 μm, 0.03 μm, 0.01 μm, 0.005 μm, etc., and is preferably 0.001-0.45 μm.

[0045] This invention does not specifically limit the number and size of hollow porous filter elements. Those skilled in the art can select them as needed. The total width of the hollow porous filter elements should be substantially the same as the width of the cathode and magnesium anode.

[0046] In this invention, when there are two or more hollow porous filter elements, an appropriate distance should be maintained between each porous filter element to facilitate filtration and sludge adhesion.

[0047] In a second aspect, the present invention provides a method for treating wastewater and simultaneously recovering resources using the anaerobic membrane bioreactor described in the first aspect, the method comprising the following steps:

[0048] Sludge is added to the reactor body, and sewage is introduced into the reactor body through the inlet. The power supply device and the stirring device are turned on to carry out sewage treatment. During the sewage treatment process, the power supply device is switched alternately between being connected to the conductive membrane anode and being connected to the magnesium anode by the triggering mechanism. Struvite is formed on the surface of the cathode plate, and gas containing methane is generated in the reactor body to complete the sewage treatment.

[0049] The method of this invention can simultaneously recover carbon, nitrogen, and phosphorus resources while treating wastewater. Carbon is mainly recovered in the form of methane, and the methane production is relatively high, increasing the proportion of methane in the gas. Nitrogen and phosphorus are recovered on the cathode in the form of struvite. The recovery of nitrogen and phosphorus by struvite precipitation not only has high efficiency in nitrogen and phosphorus removal, but struvite can also be further used as slow-release fertilizer. At the same time, the method of this invention can effectively alleviate the problem of membrane fouling, enabling the conductive membrane and magnesium anode to work together efficiently and for a long time to treat wastewater.

[0050] In the method of this invention, the formation principle of struvite is as follows: struvite is formed using a sacrificial magnesium (Mg) anode, wherein Mg ions (Mg²⁺) released from the magnesium anode... 2+ ) and ammonium (NH4) + ) and phosphoric acid (PO4) 3- Ions react in the bulk solution to form struvite.

[0051] The reason for the high methane production in the method of this invention is as follows: Mg produced at the anode 2+ The hydroxide ions (OH-) produced by the reaction of ions with hydrogen evolution at the cathode - It can absorb carbon dioxide (CO2) produced by anaerobic digestion, and work in conjunction with CO2 mineralization and biogas upgrading to increase methane production.

[0052] Preferably, the voltage generated by the power supply device is 0.4-1.0V, for example, it can be 0.4V, 0.5V, 0.6V, 0.62V, 0.64V, 0.65V, 0.68V, 0.7V, 0.72V, 0.74V, 0.75V, 0.78V, 0.8V, 0.85V, 0.9V, 0.95V or 1.0V, etc.

[0053] Preferably, the operating temperature during the wastewater treatment process is 36℃-40℃, for example, it can be 36℃, 37℃, 38℃, 39℃ or 40℃.

[0054] Preferably, within one cycle of the alternating switching, the time during which the power supply device is connected to the magnesium anode is 'a', and the time during which the power supply device is connected to the conductive film anode is 'b', where a:b = 1:(1-300), for example, it can be 1:1, 1:3, 1:5, 1:8, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, or 1:60. 1:70, 1:80, 1:85, 1:90, 1:100, 1:110, 1:120, 1:130, 1:140, 1:150, 1:160, 1:170, 1:180, 1:190, 1:200, 1:210, 1:220, 1:230, 1:240, 1:250, 1:260, 1:270, 1:280, 1:290, or 1:300, etc. Under these conditions, the membrane's antifouling effect and the recovery efficiency of carbon, nitrogen, and phosphorus can be better guaranteed.

[0055] In this invention, the hydraulic retention time and the concentration of organic solids in the sludge are adaptively adjusted according to the concentration of organic matter in the influent. For example, the concentration of organic solids in the sludge (MLVSS) is 6000-10000 mg / L, such as 6000 mg / L, 6200 mg / L, 6400 mg / L, 6600 mg / L, 7000 mg / L, 7500 mg / L, 8000 mg / L, 8500 mg / L, 9000 mg / L, 9500 mg / L, or 10000 mg / L; the hydraulic retention time of the wastewater is 4-8 days, such as 5 days, 5.5 days, 6 days, 6.5 days, 7 days, 7.5 days, or 8 days.

[0056] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0057] Compared with existing technologies, the present invention has the following beneficial effects:

[0058] (1) The anaerobic membrane bioreactor provided by the present invention is an integrated reactor body with a conductive membrane and a magnesium electrode as dual anodes. When the reactor body is working, the conductive membrane and the magnesium electrode switch anodes, which can effectively realize the membrane antifouling and the recovery of carbon, nitrogen and phosphorus.

[0059] (2) In this invention, carbon, nitrogen and phosphorus can be recovered in situ simultaneously in the anaerobic membrane bioreactor, and the recovered methane has high purity. There is no need to use post-treatment equipment to purify the biogas, which has obvious advantages over the existing technology.

[0060] (3) This invention uses a conductive film and a magnesium electrode as dual anodes, which allows the magnesium electrode plate to operate without always being under an external power supply, avoiding excessive release of magnesium, saving electrode plates, and reducing energy input. At the same time, this invention uses physicochemical precipitation to remove N and P, which is easier to operate than biological methods. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of the structure of an anaerobic membrane bioreactor provided in one embodiment of the present invention, wherein: 1. Power supply device; 2. Water inlet pipe; 3. Air bag; 4. Magnesium anode; 5. Cathode; 6. Conductive membrane anode; 7. Stirring device; 8. Water outlet pipe.

[0062] Figure 2 This is a picture of a hollow, porous filter element.

[0063] Figure 3 This is a comparison chart of membrane fouling mitigation in different groups of anaerobic membrane bioreactors.

[0064] Figure 4 This is a comparison chart of COD degradation rates from different groups of anaerobic membrane bioreactors.

[0065] Figure 5 This is a comparison chart of the methane purity produced by different groups of anaerobic membrane bioreactors.

[0066] Figure 6 This is a comparison chart of the ability of different groups of anaerobic membrane bioreactors to remove ammonia nitrogen and phosphate.

[0067] Figure 7The images show SEM images and purity diagrams of the precipitate scraped from the graphite cathode of the anaerobic membrane bioreactor in Group 3. The left side shows the SEM image, and the right side shows the purity diagram. Detailed Implementation

[0068] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0069] The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0070] This embodiment provides an anaerobic membrane bioreactor, the structural schematic of which can be found in the following diagram. Figure 1 The anaerobic membrane bioreactor includes a power supply device 1 and a reactor body. The reactor body is provided with a cathode 5 and an anode. The cathode 5 and the anode are respectively connected to the power supply device 1. The anode includes a magnesium anode 4 and a conductive membrane anode 6. The conductive membrane anode 6 includes at least one hollow porous filter element.

[0071] The anaerobic membrane bioreactor also includes a triggering mechanism, which is used to switch the connection between the power supply device 1 and the anode between a first state and a second state: in the first state, the power supply device 1 is connected to the conductive membrane anode 6; in the second state, the power supply device 1 is connected to the magnesium anode 4.

[0072] In one embodiment, the reactor body is further provided with an inlet and an outlet. The inlet is provided with an inlet pipe 2, and the outlet is provided with an outlet pipe 8. One end of the outlet pipe 8 is connected to the opening of the hollow porous filter element.

[0073] In one embodiment, a stirring device 7 is provided at the bottom of the reactor body for stirring the sludge.

[0074] In one embodiment, the triggering mechanism is: an electrical control device is provided on the connection line between the power supply device and the anode, used to regulate the connection of the power supply device with the magnesium anode or with the conductive film anode; or,

[0075] Two switches are installed on the power supply device to control the opening and closing states of the line connected to the magnesium anode and the line connected to the conductive film anode, respectively.

[0076] In one embodiment, the power supply device is a DC power supply.

[0077] In one embodiment, the reactor body is a cylindrical plexiglass reactor.

[0078] In one implementation, such as Figure 1As shown, the reactor body is also equipped with a gas collection device, which is a gas bag 3.

[0079] In one embodiment, the magnesium anode and the conductive film anode are located on opposite sides of the cathode.

[0080] In one embodiment, the area of ​​the cathode is 1 to 8 times the area of ​​the magnesium anode.

[0081] In one embodiment, the magnesium anode is disposed opposite to the cathode.

[0082] In one embodiment, the conductive film anode is disposed opposite to the cathode.

[0083] In one embodiment, the distance from the magnesium anode to the cathode is 'a' (cm), and the area of ​​the plane of the cathode facing the magnesium anode is 'S' (cm²). 2 And a / S is 1 / 10-1 / 60cm -1 In one embodiment, the cathode is made of a material capable of guano deposition, preferably including at least one of carbon materials, elemental metals, stainless steel, and conductive polymers.

[0084] In one embodiment, the carbon material includes at least one of graphite, activated carbon, graphene, carbon nanotubes, and carbon felt.

[0085] In one embodiment, the metallic element includes any one of copper, iron, nickel, chromium, platinum, gold, silver, cobalt, tin, or manganese.

[0086] In one embodiment, the magnesium anode is an electrode material with a magnesium content of 90% or more, preferably pure magnesium, AZ31 alloy, or AZ91 alloy. In another embodiment, one end of the hollow porous filter element is open, and multiple hollow porous filter elements are connected to each other via a multi-channel diversion pipe for water outlet.

[0087] In one embodiment, the opening of each porous filter element is connected to multiple pipes of a multi-channel diversion pipeline, and water is discharged through the outlet pipe.

[0088] In one embodiment, the hollow porous filter element includes: a fixing member with openings at both ends and a filter bag sealed at one end of the fixing member, the filter bag being formed by surrounding a porous conductive membrane.

[0089] In one embodiment, the porous conductive film is made of materials including titanium, titanium alloy, carbon nanotube, stainless steel, Ni-Cu alloy, Ni-Cr-Fe alloy, iron-aluminum alloy, Hastelloy B, Hastelloy C, or Hastelloy X.

[0090] In one embodiment, the pore size of the porous conductive film is less than or equal to 0.45 μm, preferably 0.001-0.45 μm.

[0091] In another embodiment of the present invention, a method for treating wastewater and simultaneously recovering resources using the above-described anaerobic membrane bioreactor is provided, the method comprising the following steps:

[0092] Sludge is added to the reactor body, and sewage is introduced into the reactor body through the inlet. The power supply device and the stirring device are turned on to carry out sewage treatment. During the sewage treatment process, the power supply device is switched alternately between being connected to the conductive membrane anode and being connected to the magnesium anode by the triggering mechanism. Struvite is formed on the surface of the cathode plate, and gas containing methane is generated in the reactor body to complete the sewage treatment.

[0093] In one embodiment, the voltage generated by the power supply device is 0.4-1.0V.

[0094] In one embodiment, the operating temperature during the wastewater treatment process is 36℃-40℃, for example, it can be 36℃, 37℃, 38℃, 39℃ or 40℃, etc.

[0095] In one embodiment, during one cycle of the alternating switching, the time during which the power supply device is connected to the magnesium anode is a, and the time during which the power supply device is connected to the conductive film anode is b, where a:b = 1:(1-300).

[0096] Based on the above implementation methods, the following are typical but non-limiting embodiments:

[0097] Example 1

[0098] This embodiment provides an anaerobic membrane bioreactor. Based on the above implementation, the triggering mechanism is as follows: a relay is installed on the connection line between the power supply device and the anode to control the connection between the power supply device and the magnesium anode or the conductive membrane anode; the power supply device is a DC power supply; the reactor body is a cylindrical plexiglass reactor; a gas collection device, which is a gas bag, is also installed on the reactor body; the magnesium anode and the conductive membrane anode are respectively located on both sides of the cathode, the cathode is a graphite plate, the magnesium anode is a magnesium plate, and both the magnesium plate and the conductive membrane anode are arranged opposite to the graphite plate; the area of ​​the cathode is 1.5 times the area of ​​the magnesium anode; the hollow porous filter element is made of porous titanium membrane with a pore size of 0.22 μm. The number of hollow porous filter elements is 3 (see actual physical diagram). Figure 2 The three hollow porous filter elements are arranged in a row, and the two-dimensional plane formed by these three elements is parallel to the graphite plate and the magnesium plate.

[0099] Example 2

[0100] This embodiment provides a method for treating wastewater using the anaerobic membrane bioreactor of Example 1. The wastewater composition is: COD 6000 mg / L, NH4+ + 300 mg / L, PO4 3- 160 mg / L, the method includes the following steps:

[0101] Sludge (with an organic solids concentration of 6000 mg / L MLVSS) is added to the reactor body. Wastewater is introduced into the reactor body through the inlet. The power supply device (voltage 0.6V) and the stirring device are turned on to generate an electric field and mix the sludge. Wastewater treatment is carried out under these conditions, with a hydraulic retention time of 8 days. During the wastewater treatment process, the power supply device is switched alternately between being connected to the conductive membrane anode and the magnesium anode by a triggering mechanism. Struvite is formed on the surface of the cathode plate, and gas containing methane is generated in the reactor body, thus completing the wastewater treatment.

[0102] In one alternating cycle, the time during which the power supply device is connected to the magnesium anode is 'a', and the time during which the power supply device is connected to the conductive film anode is 'b', where a:b = 1:60.

[0103] Comparative Example 1

[0104] This comparative example provides a conventional anaerobic membrane bioreactor, which differs from Example 1 in that it does not contain a power supply device or a magnesium anode.

[0105] Comparative Example 2

[0106] This comparative example provides an anaerobic membrane bioreactor, which differs from Example 1 in that it uses graphite plates and a conductive membrane as the anode for anode switching, and a graphite plate as the cathode. The applied voltage is the same as in Example 1.

[0107] This comparative example also provides a method for treating wastewater using the above-described anaerobic membrane bioreactor, with all parameters set in the same manner as in Example 2.

[0108] Performance testing:

[0109] Performance tests were conducted on Example 2, Comparative Example 1, and Comparative Example 2, and the groups were as follows: Comparative Example 1 was designated as 1#, Comparative Example 2 as 2#, and Example 2 as 3#.

[0110] 1. Membrane fouling test

[0111] During long-term operation, the transmembrane pressure difference (TMP) was monitored, and TMP was used as an evaluation index for membrane fouling. When TMP reached 80 kPa, the membrane was considered fouled and needed to be replaced. At this point, three groups (1#, 2#, and 3#) of membranes were replaced uniformly to compare the membrane fouling mitigation capabilities of different groups. Figure 3 As shown, with the electrochemical reaction and the effect of magnesium, the fouling mitigation effect of membrane #3 became more and more significant. Compared with the control group #1, membrane fouling was reduced by 95%, while group #2, which did not contain magnesium electrodes, could only be reduced by 20%.

[0112] 2. Biogas production and COD degradation status

[0113] Figure 4 As can be seen, groups #1, #2, and #3 all achieved a COD degradation rate of over 95% after reaching stable operation following acclimatization. However, group #3 adapted to the environment more quickly during the acclimatization period because the stronger electrochemical reactions within the system resulted in a higher pH, which helped suppress acidification during the acclimatization period, allowing the anaerobic sludge to complete the four stages of the anaerobic reaction more rapidly. Figure 5 As can be seen during stable operation, the purity of methane in #3 can reach 94%, which is higher than 68% in #1 and 67% in #2. The methane production also increased from 692ml / d in #1 to 790ml / d.

[0114] 3. Nitrogen and phosphorus removal status

[0115] from Figure 6 As can be seen, #1 and #2 have virtually no ability to remove ammonia nitrogen and phosphate, but in #3, the ammonia nitrogen removal rate is 30.59% and the phosphate removal rate is 99%.

[0116] 4. Formation of guano

[0117] pass Figure 7 As can be seen, during the stable operation of the reaction, the sediment on the graphite cathode plate #3 was scraped off to determine the formation of struvite. The SEM image on the left shows the formation of needle-like prismatic crystals, proving the presence of struvite. The calculated struvite purity of the sediment was 60.64%, and the struvite formation amount was 0.08 g / d.

[0118] Example 3

[0119] The only difference between this embodiment and Embodiment 2 is that a:b = 1:240.

[0120] Example 3 was tested using the same method as Example 2. The calculated purity of the struvite in the sediment was 28.37%, and the struvite production was 0.04 g / d. The ammonia nitrogen removal rate was 25%, and the phosphate removal rate was 99%. Furthermore, this example effectively alleviates membrane fouling and improves biogas purity.

[0121] Example 4

[0122] The only difference between this embodiment and Embodiment 2 is that a:b = 1:1.

[0123] Example 3 was tested using the same method as Example 2. Calculations showed that the purity of the struvite in the sediment was 72.85%, the struvite production was 0.29 g / d, the ammonia nitrogen removal rate was 36%, and the phosphate removal rate was 99%. Simultaneously, this example effectively alleviates membrane fouling and improves biogas purity. The applicant declares that this invention is illustrated through the above examples, but the invention is not limited to the above detailed methods, i.e., it does not mean that the invention must rely on the above detailed methods to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product, additions of auxiliary components, and selection of specific methods all fall within the scope of protection and disclosure of this invention.

Claims

1. An integrated anaerobic membrane bioreactor, characterized in that, The anaerobic membrane bioreactor includes a power supply device and a reactor body. The reactor body is provided with a cathode and an anode. The cathode and the anode are respectively connected to the power supply device. The anode includes a magnesium anode and a conductive membrane anode. The conductive membrane anode includes at least one hollow porous filter element. The anaerobic membrane bioreactor also includes a triggering mechanism, which is used to switch the connection between the power supply device and the anode between a first state and a second state: in the first state, the power supply device is connected to the conductive membrane anode; In the second state, the power supply device is connected to the magnesium anode; The hollow porous filter element includes: a fixing member with openings at both ends and a filter bag sealed at one end of the fixing member, the filter bag being formed by surrounding a porous conductive membrane; The porous conductive film is made of materials including titanium, titanium alloy, carbon nanotube, stainless steel, Ni-Cu alloy, Ni-Cr-Fe alloy, iron-aluminum alloy, Hastelloy B, Hastelloy C or Hastelloy X. The magnesium anode and the conductive film anode are located on opposite sides of the cathode, respectively.

2. The anaerobic membrane bioreactor according to claim 1, characterized in that, The triggering mechanism is: an electrical control device is provided on the connection line between the power supply device and the anode, which is used to regulate the connection between the power supply device and the magnesium anode or the conductive film anode; or, Two switches are installed on the power supply device to control the opening and closing states of the line connected to the magnesium anode and the line connected to the conductive film anode, respectively.

3. The anaerobic membrane bioreactor according to claim 1, characterized in that, The reactor body is also equipped with a stirring device for stirring the sludge.

4. The anaerobic membrane bioreactor according to claim 1, characterized in that, The reactor body is also equipped with a gas collection device.

5. The anaerobic membrane bioreactor according to claim 1, characterized in that, The area of ​​the cathode is 1 to 8 times the area of ​​the magnesium anode.

6. The anaerobic membrane bioreactor according to claim 1, characterized in that, The magnesium anode is positioned opposite to the cathode.

7. The anaerobic membrane bioreactor according to claim 1, characterized in that, The conductive film anode is positioned opposite to the cathode.

8. The anaerobic membrane bioreactor according to claim 1, characterized in that, The distance from the magnesium anode to the cathode is 'a', in cm, and the area of ​​the plane of the cathode facing the magnesium anode is 'S', in cm². 2 And a / S is 1 / 10-1 / 60cm -1 .

9. The anaerobic membrane bioreactor according to claim 1, characterized in that, The cathode is made of a material capable of depositing guano.

10. The anaerobic membrane bioreactor according to claim 9, characterized in that, The cathode is at least one of carbon materials, elemental metals, stainless steel, and conductive polymers.

11. The anaerobic membrane bioreactor according to claim 10, characterized in that, The carbon material includes at least one of graphite, activated carbon, graphene, carbon nanotubes, and carbon felt.

12. The anaerobic membrane bioreactor according to claim 10, characterized in that, The metallic element includes any one of copper, iron, nickel, chromium, platinum, gold, silver, cobalt, tin, or manganese.

13. The anaerobic membrane bioreactor according to claim 1, characterized in that, The magnesium anode is an electrode material with a magnesium content of over 90%.

14. The anaerobic membrane bioreactor according to claim 13, characterized in that, The magnesium anode is pure magnesium, AZ31 alloy, or AZ91 alloy.

15. The anaerobic membrane bioreactor according to claim 1, characterized in that, The hollow porous filter element is open at one end, and multiple hollow porous filter elements are connected to each other for water outlet using a multi-channel diversion pipe.

16. The anaerobic membrane bioreactor according to claim 1, characterized in that, The pore size of the porous conductive film is less than or equal to 0.45 μm.

17. The anaerobic membrane bioreactor according to claim 16, characterized in that, The porous conductive film has a pore size of 0.001-0.45 μm.

18. A method for treating wastewater and simultaneously recovering resources using an anaerobic membrane bioreactor as described in any one of claims 1-17, characterized in that, The method includes the following steps: Sludge is added to the reactor body, and sewage is introduced into the reactor body through the inlet. The power supply device and the stirring device are turned on to carry out sewage treatment. During the sewage treatment process, the power supply device is switched alternately between being connected to the conductive membrane anode and being connected to the magnesium anode by the triggering mechanism. Struvite is formed on the surface of the cathode plate, and gas containing methane is generated in the reactor body to complete the sewage treatment.

19. The method according to claim 18, characterized in that, The voltage generated by the power supply device is 0.4V-1.0V.

20. The method according to claim 18, characterized in that, During the wastewater treatment process, the operating temperature is 36℃-40℃.

21. The method according to claim 18, characterized in that, Within one cycle of the alternating switching, the time during which the power supply device is connected to the magnesium anode is a, and the time during which the power supply device is connected to the conductive film anode is b, where a:b=1:(1-300).

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