Membrane bio-membrane reactor and method for efficiently coupling biogas recycling and denitrification by using same

Abstract

The invention discloses a membrane bio-membrane reactor and a method for efficiently coupling biogas recycling and denitrification by using the same, and relates to a reactor and a method for recycling and denitrifying biogas by using the same. The invention aims to solve the technical bottleneck problems that the traditional denitrification process depends on an external carbon source and is high in cost, and the existing methane-based membrane bio-membrane reactor cannot fully utilize biogas resources. The invention discloses a membrane bio-membrane reactor. Comprising a biogas high-pressure gas cylinder, a high-pressure gas pressure reducing valve, a reactor main body, a hollow fiber membrane assembly, a reactor main body water outlet, a reactor main body water inlet, a water inlet device, a reflux device, a circulating water outlet, a circulating water inlet, a gas sampling port, a reflux device water outlet, a liquid sampling port, a pH measuring instrument, a water outlet liquid sealing device and an atmosphere communication port. The mechanism of'one source and two purposes' (serving as an electron donor and converting into a carbon source in situ) of biogas methane is the core of realizing efficient denitrification and biogas resource utilization.

Description

Technical Field

[0001] The invention relates to a reactor and a method for utilizing the same to convert biogas into resources and perform denitrification. Background Art

[0002] Methane (CH4) has attracted widespread attention as an electron donor for MBfR (Membrane Biofilm Reactor) due to its widespread availability and low cost. However, existing methane-based MBfR systems still have significant limitations in practical application: first, methane's low solubility in water limits its mass transfer rate and bioavailability. More importantly, existing research and applications have largely considered methane solely as an electron donor, failing to fully explore and utilize its potential as a carbon resource. Specifically, methane can be converted into certain organic intermediates (such as acetic acid and methanol) under the action of microorganisms. These products themselves can serve as high-quality carbon sources in the denitrification process. If this conversion process can be effectively controlled and utilized in situ, the requirement for external carbon sources could be significantly reduced or even eliminated, which is of great significance for treating low-C / N wastewater.

[0003] Biogas is a major source of methane. As a product of anaerobic digestion, its main components are methane and carbon dioxide, making it a readily available renewable energy source. Its application in MBfR (Medium-Boundary Reflux) not only allows methane to serve as an electron donor, but also enables further partial oxidation of methane and the use of its metabolites as an endogenous carbon source for synergistic denitrification, maximizing biogas resource utilization. This "one source, two uses" strategy—where methane serves as both an electron donor and an in situ organic carbon source through microbial conversion—is a key approach to improving denitrification efficiency, reducing operating costs, and achieving sustainable wastewater treatment. However, it has yet to be fully and effectively developed and applied. Therefore, developing a novel reactor and operating method that can efficiently couple biogas resource utilization (particularly methane's dual functions as an electron donor and carbon source) with the MBfR denitrification process is of great theoretical significance and practical application value, as it addresses the carbon source dependence, high costs, and inadequate biogas utilization inherent in existing technologies. Summary of the Invention

[0004] The purpose of the present invention is to solve the technical bottleneck problems of traditional denitrification process relying on external carbon source, high cost, and insufficient utilization of biogas resources by existing methane-based MBfR, and to provide a membrane biofilm reactor and a method for efficiently coupling biogas resource utilization and denitrification using the reactor.

[0005] The present invention provides a membrane biofilm reactor and a method for efficiently coupling biogas resource utilization and denitrification using the reactor, aiming to solve the technical bottlenecks of traditional denitrification processes that rely on external carbon sources, are high in cost, and that existing methane-based MBfRs do not fully utilize biogas resources. By combining a specific hollow fiber membrane module layout and a sequencing batch reactor (SBR) operation mode, favorable conditions are created for efficient biogas mass transfer, stable biofilm attachment, and the enrichment and synergistic metabolism of key microbial populations (such as methanotrophic bacteria and denitrifying bacteria); the invention not only utilizes methane in biogas as The main electron donor in the denitrification process, more importantly, by optimizing the microbial environment and operating conditions in the reactor, the partial oxidation of methane is promoted to be converted in situ into soluble organic intermediate metabolites (such as acetic acid, etc.), which are then used by denitrifying bacteria as endogenous carbon sources, thereby significantly reducing or even eliminating the dependence on external organic carbon sources; through the dual synergistic effects of the above-mentioned biogas methane as an "electron donor" and "in situ carbon source", especially for low carbon-nitrogen ratio wastewater, the denitrification efficiency and total nitrogen removal rate can be greatly improved, overcoming the limitations of traditional processes in the treatment of such wastewater.

[0006] A membrane biofilm reactor, comprising a biogas high-pressure cylinder 1, a high-pressure gas pressure reducing valve 2, a reactor body 3, a hollow fiber membrane assembly 4, a reactor body water outlet 5, a reactor body water inlet 6, a water inlet device 7, a reflux device 10, a circulating water outlet 11, a circulating water inlet 13, a gas sampling port 14, a reflux device water outlet 15, a liquid sampling port 16, a pH measuring instrument 17, a water outlet liquid seal device 18, and an atmosphere communication port 19; The reactor body 3 is provided with a reactor body water outlet 5 and a reactor body water inlet 6, and a hollow fiber membrane assembly 4 is provided in the reactor body 3; the biogas high-pressure gas cylinder 1 is connected to the hollow fiber membrane assembly 4 through a gas pipeline; the water inlet device 7 is connected to the reactor body water inlet 6 through a water inlet pipeline; The reflux device 10 is provided with a circulating water outlet 11, a circulating water inlet 13, a gas sampling port 14, a reflux device outlet 15 and a liquid sampling port 16; a pH measuring instrument 17 is provided inside the reflux device 10; The reactor body water outlet 5 is connected to the circulating water inlet 13 through a liquid pipeline; the circulating water outlet 11 is connected to the reactor body water inlet 6 through a circulating pipeline; the reflux device water outlet 15 is connected to the inside of the water outlet liquid seal device 18 through the water outlet pipeline; the water outlet liquid seal device 18 is provided with an atmosphere communication port 19.

[0007] In the present invention, the biogas high-pressure cylinder 1 is used to store and supply biogas, preferably biogas produced by actual anaerobic fermentation, and simulated biogas can be used in the experimental stage; The hollow fiber membrane module 4 can optimize gas diffusion and biofilm attachment; the hollow fiber membrane module 4 can achieve bubble-free aeration of biogas and provide a large surface area for microorganisms to attach and grow; The first air bag 9 is used to buffer or collect gas that may be generated in the pipeline; The reactor body water outlet 5 is connected to the circulating water inlet 13 through a liquid pipeline; the circulating water outlet 11 is connected to the reactor body water inlet 6 through a circulating pipeline; an internal circulation is formed to enhance mass transfer and reactant mixing.

[0008] The gas sampling port 14 is used to monitor biogas consumption and conversion; The liquid sampling port 16 is used to monitor water quality parameters; The pH measuring instrument 17 is used to monitor the reaction environment in real time; The atmosphere communication port 19 is used to stabilize the system pressure; The second gas bag 20 is used to collect the treated gas.

[0009] A method for efficiently coupling biogas resource utilization and denitrification, using a membrane biofilm reactor, is specifically completed by the following steps: 1. The microbial seed liquid is loaded into the reflux device 10, and the simulated wastewater is loaded into the water inlet device 7; the microbial seed liquid in the reflux device 10 is inoculated into the reactor body 3 through the circulation pump 12, and the simulated wastewater in the water inlet device 7 is replenished into the reactor body 3 through the water inlet pump 8. After the simulated wastewater and the microbial seed liquid are fully mixed to obtain a mixed liquid, argon gas with a purity of 99.99% is introduced through the liquid sampling port 16, and the mixed liquid is aerated to an anaerobic state using argon gas with a purity of 99.99%, and then the reactor body 3 is sealed; the high-pressure gas pressure reducing valve 2 is opened, and the simulated biogas in the biogas high-pressure gas cylinder 1 enters the hollow fiber membrane module 4; the temperature of the reactor body 3 is maintained at room temperature, the speed of the circulation pump 12 is set to 65 mL / min, the speed of the water inlet pump 8 is set to 5 mL / min, and the pressure in the hollow fiber membrane module 4 is 1.25 atm; The simulated wastewater described in step 1 is composed of KH2PO4, MgSO4·7H2O, CaCl2·2H2O, NH4Cl, acidic trace elements, alkaline trace elements and distilled water, wherein the concentration of KH2PO4 is 0.075 g / L, the concentration of MgSO4·7H2O is 0.2 g / L, the concentration of CaCl2·2H2O is 0.3 g / L, the concentration of NH4Cl is 0.09 g / L, the concentration of acidic trace elements is 0.5 mL / L, and the concentration of alkaline trace elements is 0.2 mL / L; Second, nitrate or nitrite is added to the simulated wastewater, and then pumped into the reactor body 3 through the water inlet device 7, and then operated in a sequencing batch reactor mode to achieve biogas resource utilization and denitrification process.

[0010] The microbial seed liquid in the present invention is a mixed sludge obtained by mixing farmland drainage ditch bottom mud, anaerobic digestion tank sludge and recycled sludge from Harbin Wenchang Sewage Treatment Plant. It is domesticated under the condition of using methane as the only electron donor and carbon source. After long-term cultivation, it is mainly composed of methane oxidizing bacteria, denitrifying bacteria and fermentation acid-producing bacteria.

[0011] The working principle of the present invention is as follows: In the present invention, nitrate or nitrite is added to the simulated wastewater, and the nitrogen-containing wastewater in the water inlet device 7 is pumped into the reactor body 3 through the water inlet pump 8. At the same time, biogas (mainly composed of methane and carbon dioxide) is passed from the high-pressure gas cylinder 1 through the high-pressure gas pressure reducing valve 2 and then into the inner cavity of the hollow fiber membrane module 4. The biogas diffuses through the microporous structure of the non-porous hollow fiber membrane in an osmotic manner into the biofilm growing on the outer surface of the membrane. Within a biofilm, the following key coordinated biochemical reactions occur: Partial oxidation of methane and in situ generation of carbon sources: Under the action of microorganisms (such as methanotrophs), part of the methane is oxidized, and the soluble organic intermediates produced in their metabolic pathways (such as acetic acid, methanol, etc., the specific products depend on the enriched microbial population and operating conditions) are released into the liquid phase of the biofilm.

[0012] Autotrophic and heterotrophic synergistic denitrification: A portion of the methane is directly used as an electron donor by specific methane-oxidizing and denitrifying microorganisms to reduce nitrate (NO3-N) or nitrite (NO2-N) in the wastewater to nitrogen gas (N2). The organic intermediates generated by the partial oxidation of methane in the previous step serve as high-quality endogenous carbon sources and electron donors, efficiently utilized by heterotrophic denitrifying bacteria to further reduce nitrate or nitrite.

[0013] This dual-use mechanism of biogas methane (serving as both an electron donor and an in-situ carbon source) is the core of the present invention's efficient denitrification and biogas resource utilization. The reactor effluent is discharged through a circulation pump 12 and an outlet liquid seal 18, ensuring stable system operation. The sequencing batch reactor (SBR) operation facilitates microbial screening and enrichment, as well as adaptability to changes in influent load.

[0014] Beneficial effects of the present invention: This invention innovatively and for the first time deeply couples biogas resource utilization with the denitrification process in MBfR, achieving the following significant technical effects and advantages: (1) The most significant advantage of this invention is that it achieves dual uses of methane in biogas: it serves as an electron donor and, through microbial conversion, generates a usable organic carbon source (such as acetic acid and other metabolites) in situ. This fundamentally overcomes the traditional denitrification process's reliance on an external carbon source, as well as the denitrification efficiency bottleneck of existing methane-based MBfRs in low C / N ratio wastewater due to insufficient carbon sources.

[0015] (2) The present invention not only utilizes the reducing power of methane, but also bioconverts it into higher-value organic matter for direct denitrification, maximizing the energy and resource potential of biogas and achieving efficient conversion from "waste" to "effective resource." Since the addition of external organic carbon sources (such as methanol and sodium acetate) is not required or greatly reduced, the operating costs of sewage treatment plants can be significantly reduced.

[0016] (3) In-situ carbon source generation avoids system shocks caused by uneven or fluctuating addition of external carbon sources. The SBR operation mode further enhances the system's adaptability and robustness to changes in influent water quality and quantity. The stable air supply of the hollow fiber membrane and the good adhesion of the biofilm ensure long-term operational reliability. The present invention is suitable for deep denitrification of industrial wastewater or municipal wastewater with high ammonia nitrogen and low C / N ratio, such as certain chemical wastewater, aquaculture wastewater terminal treatment, and municipal sewage treatment plant upgrading.

[0017] The present invention provides a new, economical, efficient, and environmentally friendly wastewater denitrification technology. Its core lies in achieving dual efficient utilization of methane in biogas as an electron donor and an in-situ carbon source through internal reactor design and operation regulation, thereby solving the difficult problem of efficient denitrification of low C / N ratio wastewater under low-cost conditions, and has broad prospects for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of a membrane biofilm reactor according to the present invention, in which 1 is a biogas high-pressure cylinder, 2 is a high-pressure gas pressure reducing valve, 3 is a reactor body, 4 is a hollow fiber membrane assembly, 5 is a water outlet of the reactor body, 6 is a water inlet of the reactor body, 7 is a water inlet device, 8 is a water inlet pump, 9 is an air bag, 10 is a reflux device, 11 is a circulating water outlet, 12 is a circulating pump, 13 is a circulating water inlet, 14 is a gas sampling port, 15 is a reflux device outlet, 16 is a liquid sampling port, 17 is a pH measuring instrument, 18 is a water outlet liquid seal device, 19 is an atmosphere communication port, and 20 is an air bag; Figure 2 (a) is a graph showing the inlet nitrate concentration, effluent nitrate concentration, and HRT data of the membrane biofilm reactor in Example 2; (b) is a graph showing the nitrate inlet load, nitrate removal rate, and nitrate reduction efficiency of the membrane biofilm reactor in Example 2; Figure 3This is a graph of the short-chain fatty acid concentration in the effluent of the membrane biofilm reactor in Example 2. DETAILED DESCRIPTION

[0019] Specific embodiment 1: This embodiment is a membrane biofilm reactor, including a biogas high-pressure cylinder 1, a high-pressure gas pressure reducing valve 2, a reactor body 3, a hollow fiber membrane module 4, a reactor body water outlet 5, a reactor body water inlet 6, a water inlet device 7, a reflux device 10, a circulating water outlet 11, a circulating water inlet 13, a gas sampling port 14, a reflux device water outlet 15, a liquid sampling port 16, a pH measuring instrument 17, a water outlet liquid seal device 18 and an atmosphere communication port 19; The reactor body 3 is provided with a reactor body water outlet 5 and a reactor body water inlet 6, and a hollow fiber membrane assembly 4 is provided in the reactor body 3; the biogas high-pressure gas cylinder 1 is connected to the hollow fiber membrane assembly 4 through a gas pipeline; the water inlet device 7 is connected to the reactor body water inlet 6 through a water inlet pipeline; The reflux device 10 is provided with a circulating water outlet 11, a circulating water inlet 13, a gas sampling port 14, a reflux device outlet 15 and a liquid sampling port 16; a pH measuring instrument 17 is provided inside the reflux device 10; The reactor body water outlet 5 is connected to the circulating water inlet 13 through a liquid pipeline; the circulating water outlet 11 is connected to the reactor body water inlet 6 through a circulating pipeline; the reflux device water outlet 15 is connected to the inside of the water outlet liquid seal device 18 through the water outlet pipeline; the water outlet liquid seal device 18 is provided with an atmosphere communication port 19.

[0020] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the water inlet device 7 further includes a first air bag 9, which is connected to the interior of the water inlet device 7 via a gas pipeline. Other steps are the same as those of specific embodiment 1.

[0021] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that a water inlet pump 8 is provided on the pipeline connecting the water inlet device 7 and the water inlet 6 of the reactor body. Other steps are the same as those of specific embodiment 1 or 2.

[0022] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that a high-pressure gas pressure reducing valve 2 is installed on the gas pipeline connecting the biogas high-pressure cylinder 1 and the hollow fiber membrane module 4. The high-pressure gas pressure reducing valve 2 controls the gas flow rate of the biogas high-pressure cylinder 1. The other steps are the same as specific embodiments 1 to 3.

[0023] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that a circulating pump 12 is provided on the pipeline connecting the circulating water outlet 11 and the reactor body water inlet 6. The other steps are the same as those of specific embodiments 1 to 4.

[0024] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the water outlet liquid sealing device 18 is further provided with a second air bag 20, which is connected to the interior of the water outlet liquid sealing device 18 via a gas pipeline. The other steps are the same as specific embodiments 1 to 5.

[0025] Specific embodiment seven: This embodiment is a method for efficiently coupling biogas resource utilization and denitrification, which uses a membrane biofilm reactor and is specifically completed in the following steps: 1. The microbial seed liquid is loaded into the reflux device 10, and the simulated wastewater is loaded into the water inlet device 7; the microbial seed liquid in the reflux device 10 is inoculated into the reactor body 3 through the circulation pump 12, and the simulated wastewater in the water inlet device 7 is replenished into the reactor body 3 through the water inlet pump 8. After the simulated wastewater and the microbial seed liquid are fully mixed to obtain a mixed liquid, argon gas with a purity of 99.99% is introduced through the liquid sampling port 16, and the mixed liquid is aerated to an anaerobic state using argon gas with a purity of 99.99%, and then the reactor body 3 is sealed; the high-pressure gas reducing valve 2 is opened, and the simulated biogas in the biogas high-pressure gas cylinder 1 enters the hollow fiber membrane module 4; the temperature of the reactor body 3 is maintained at room temperature, the speed of the circulation pump 12 is set to 65mL / min, the speed of the water inlet pump 8 is set to 5mL / min, and the pressure in the hollow fiber membrane module 4 is controlled at 1.25atm by the high-pressure gas reducing valve 2; The simulated wastewater described in step 1 is composed of KH2PO4, MgSO4·7H2O, CaCl2·2H2O, NH4Cl, acidic trace elements, alkaline trace elements and distilled water, wherein the concentration of KH2PO4 is 0.075 g / L, the concentration of MgSO4·7H2O is 0.2 g / L, the concentration of CaCl2·2H2O is 0.3 g / L, the concentration of NH4Cl is 0.09 g / L, the concentration of acidic trace elements is 0.5 mL / L, and the concentration of alkaline trace elements is 0.2 mL / L; Second, nitrate or nitrite is added to the simulated wastewater, and then pumped into the reactor body 3 through the water inlet device 7, and then operated in a sequencing batch reactor mode to achieve biogas resource utilization and denitrification process.

[0026] In this embodiment, the microbial seed liquid is a mixed sludge obtained by mixing farmland drainage ditch sediment, anaerobic digestion tank sludge and recycled sludge from the Wenchang Sewage Treatment Plant in Harbin. It is domesticated under conditions where methane is the only electron donor and carbon source. After long-term cultivation, it is mainly composed of methane oxidizing bacteria, denitrifying bacteria and fermentation acid-producing bacteria.

[0027] Specific embodiment eight: This embodiment differs from specific embodiments one to seven in that the acidic trace elements are composed of FeSO4·7H2O, CoCl2·6H2O, ZnSO4·7H2O, MnCl2·4H2O, CuSO4·5H2O, NiCl2·6H2O, H3BO4, HCl and distilled water, wherein the concentration of FeSO4·7H2O is 2.085 g / L, the concentration of CoCl2·6H2O is 0.12 g / L, the concentration of ZnSO4·7H2O is 0.068 g / L, the concentration of MnCl2·4H2O is 0.5 g / L, the concentration of CuSO4·5H2O is 0.32 g / L, the concentration of NiCl2·6H2O is 0.095 g / L, the concentration of H3BO4 is 0.014 g / L, and the concentration of HCl is 100 mmol / L. The other steps are the same as those in Specific Embodiments 1 to 7.

[0028] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the alkaline trace elements are composed of NaOH, Na2WO4·2H2O, KMnO4, SeO2, and distilled water, wherein the concentration of NaOH is 0.4 g / L, the concentration of Na2WO4·2H2O is 0.05 g / L, the concentration of KMnO4 is 0.242 g / L, and the concentration of SeO2 is 0.67 g / L. The other steps are the same as specific embodiments 1 to 8.

[0029] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that the amount of nitrate or nitrite added in step 2 is 200 mg-N / L. The other steps are the same as those of specific embodiments 1 to 9.

[0030] The following examples are used to verify the beneficial effects of the present invention: Example 1: A membrane biofilm reactor for efficiently coupling biogas resource utilization and denitrification, comprising a biogas high-pressure cylinder 1, a high-pressure gas pressure reducing valve 2, a reactor body 3, a hollow fiber membrane assembly 4, a reactor body water outlet 5, a reactor body water inlet 6, a water inlet device 7, a reflux device 10, a circulating water outlet 11, a circulating water inlet 13, a gas sampling port 14, a reflux device water outlet 15, a liquid sampling port 16, a pH measuring instrument 17, a water outlet liquid seal device 18, and an atmosphere communication port 19; The reactor body 3 is provided with a reactor body water outlet 5 and a reactor body water inlet 6, and a hollow fiber membrane assembly 4 is provided in the reactor body 3; the biogas high-pressure gas cylinder 1 is connected to the hollow fiber membrane assembly 4 through a gas pipeline; the water inlet device 7 is connected to the reactor body water inlet 6 through a water inlet pipeline; The reflux device 10 is provided with a circulating water outlet 11, a circulating water inlet 13, a gas sampling port 14, a reflux device outlet 15 and a liquid sampling port 16; a pH measuring instrument 17 is provided inside the reflux device 10; The reactor body water outlet 5 is connected to the circulating water inlet 13 through a liquid pipeline; the circulating water outlet 11 is connected to the reactor body water inlet 6 through a circulating pipeline; the reflux device water outlet 15 is connected to the interior of the water outlet liquid seal device 18 through a water outlet pipeline; the water outlet liquid seal device 18 is provided with an atmosphere communication port 19; In the present invention, the biogas high-pressure cylinder 1 is used to store and supply biogas, preferably biogas produced by actual anaerobic fermentation, and simulated biogas can be used in the experimental stage; The hollow fiber membrane module 4 can optimize gas diffusion and biofilm attachment; the hollow fiber membrane module 4 can achieve bubble-free aeration of biogas and provide a large surface area for microorganisms to attach and grow; The first air bag 9 is used to buffer or collect gas that may be generated in the pipeline; The reactor body water outlet 5 is connected to the circulating water inlet 13 through a liquid pipeline; the circulating water outlet 11 is connected to the reactor body water inlet 6 through a circulating pipeline; an internal circulation is formed to enhance mass transfer and reactant mixing.

[0031] The gas sampling port 14 is used to monitor biogas consumption and conversion; The liquid sampling port 16 is used to monitor water quality parameters; The pH measuring instrument 17 is used to monitor the reaction environment in real time; The atmosphere communication port 19 is used to stabilize the system pressure; The second gas bag 20 is used to collect the treated gas.

[0032] Example 2: A method for efficiently coupling biogas resource utilization and denitrification, using a membrane biofilm reactor as described in Example 1, is specifically accomplished by the following steps: 1. The microbial seed liquid is loaded into the reflux device 10, and the simulated wastewater is loaded into the water inlet device 7; the microbial seed liquid in the reflux device 10 is inoculated into the reactor body 3 through the circulation pump 12, and the simulated wastewater in the water inlet device 7 is replenished into the reactor body 3 through the water inlet pump 8. After the simulated wastewater and the microbial seed liquid are fully mixed to obtain a mixed liquid, argon gas with a purity of 99.99% is introduced through the liquid sampling port 16, and the mixed liquid is aerated to an anaerobic state using argon gas with a purity of 99.99%, and then the reactor body 3 is sealed; the high-pressure gas reducing valve 2 is opened, and the simulated biogas in the biogas high-pressure gas cylinder 1 enters the hollow fiber membrane module 4; the temperature of the reactor body 3 is maintained at room temperature, the speed of the circulation pump 12 is set to 65mL / min, the speed of the water inlet pump 8 is set to 5mL / min, and the pressure in the hollow fiber membrane module 4 is controlled at 1.25atm by the high-pressure gas reducing valve 2; The simulated wastewater described in step 1 is composed of KH2PO4, MgSO4·7H2O, CaCl2·2H2O, NH4Cl, acidic trace elements, alkaline trace elements and distilled water, wherein the concentration of KH2PO4 is 0.075g / L, the concentration of MgSO4·7H2O is 0.2g / L, the concentration of CaCl2·2H2O is 0.3g / L, the concentration of NH4Cl is 0.09g / L, the concentration of acidic trace elements is 0.5mL / L, and the concentration of alkaline trace elements is 0.2mL / L; the acidic trace elements are composed of FeSO4·7H2O, CoCl2·6H2O, ZnSO4·7H2O, MnCl2·4H2O, CuSO4·5H2O, NiCl2·6H2O, H3BO4, HCl and distilled water, wherein FeSO4 The concentration of ZnSO4·7H2O is 2.085 g / L, the concentration of CoCl2·6H2O is 0.12 g / L, the concentration of ZnSO4·7H2O is 0.068 g / L, the concentration of MnCl2·4H2O is 0.5 g / L, the concentration of CuSO4·5H2O is 0.32 g / L, the concentration of NiCl2·6H2O is 0.095 g / L, the concentration of H3BO4 is 0.014 g / L, and the concentration of HCl is 100 mmol / L; the alkaline trace elements are composed of NaOH, Na2WO4·2H2O, KMnO4, SeO2 and distilled water, wherein the concentration of NaOH is 0.4 g / L, the concentration of Na2WO4·2H2O is 0.05 g / L, the concentration of KMnO4 is 0.242 g / L, and the concentration of SeO2 is 0.67 g / L; The composition of the simulated biogas described in step 1 is 60% CH4+39.7% CO2+0.3% H2S; The microbial seed solution in step 1 is obtained by mixing farmland drainage ditch sediment, anaerobic digester sludge and recycled sludge from the Wenchang Wastewater Treatment Plant in Harbin, and is domesticated under conditions where methane is the only electron donor and carbon source. After long-term cultivation, the microbial seed solution is mainly composed of methane oxidizing bacteria, denitrifying bacteria and fermentative acid-producing bacteria; Second, nitrate is added to the simulated wastewater, which is then pumped into the reactor body 3 through the water inlet device 7, and then operated in a sequencing batch reactor mode to achieve biogas resource utilization and denitrification processes; The nitrate described in step 2 is NaNO3; The amount of nitrate added in step 2 is 200 mg-N / L.

[0033] Table 1 shows the data of the membrane biofilm reactor operation stage; The operating results of the reactor operation phases 1-9 with nitrate as electron acceptor, 60% methane, 39.7% carbon dioxide and 0.3% hydrogen sulfide as electron donors are as follows: Figure 2As shown in Figure 3, the nitrate removal rate in the reactor continued to increase with decreasing HRT during operation stages 1–7 (days 369–499). At influent loadings of 399.76, 480, 560, 640, 720, 800, and 880 mg-N / L·d, the average nitrate removal rates were 400, 480, 559.54, 639.07, 712.33, 768.83, and 801.41 mg-N / L·d, respectively. The corresponding average nitrate reduction efficiencies were 99.94%, 100%, 99.92%, 99.86%, 98.93%, 96.10%, and 91.07%, respectively. On day 488, at an influent nitrate loading of 880 mg-N / L·d, the maximum nitrate removal rate reached 827.23 mg-N / L·d, with a reduction efficiency of 94.00%. After the seventh stage of operation, the influent nitrate concentration was further increased. In stage 8, at an influent nitrate loading of 960 mg-N / L·d, the average nitrate removal rate reached 855.23 mg-N / L·d, corresponding to a reduction efficiency of 89.09%. During stages 7 and 8, the effluent nitrate concentration remained consistently above 10 mg-N / L·d and showed an increasing trend, reaching a peak effluent concentration of 31.03 mg-N / L·d on day 513. Nitrate reduction in the MBfR reached saturation after the eighth stage of operation. Due to the gradual accumulation of nitrate in the effluent, the nitrate removal rate could not be further effectively increased. Therefore, the reactor's influent loading was adjusted back to 400 mg-N / L·d to restore the functional microbial status of the reactor. Following this adjustment (stage 9), the reactor was able to completely reduce nitrate at 400 mg-N / L·d. After 14 days of resumed operation, the reactor's nitrate removal efficiency remained at 100%. During the operation (phases 1–9, corresponding to operation time 369–528 days), the concentrations of volatile fatty acids (SCFAs) were as follows Figure 3As shown, the reactor exhibited distinct stage-by-stage fluctuations. During the initial operation phase (Stages 1–2, days 369–405), SCFA concentrations gradually increased as the reactor adapted to the sulfur-containing gas supply environment. Acetic acid, the primary component, gradually increased in concentration from 218.54 mg / L to a peak of 393.53 mg / L on day 385. Total volatile acid concentrations also rose simultaneously, reaching a peak of 507.04 mg / L on day 386. During this phase, the HRT decreased from 0.5 to 0.36 days. The accumulation of SCFAs indicates that the microorganisms were still adapting to the sulfur, with acid production continuing to increase. It is speculated that methane oxidation to intermediates such as acetic acid was relatively active during this phase. Subsequently, during Stages 3–4 (days 406–440), SCFA concentrations showed a significant downward trend. Acetic acid concentrations gradually decreased from 266.84 mg / L to 82.0 mg / L on day 427, while total SCFAs also decreased from 324.89 to 99.52 mg / L. Notably, during Phases 5–8 (days 441–514), volatile acidity levels dropped almost to the limit of detection or even to zero, indicating a significant suppression of acid production in the system. This may be due to the low HRT (0.21–0.23 days) and the resulting adjustments in microbial community structure caused by long-term operation. Furthermore, the presence of HS in the gas supply may have triggered sulfide accumulation, inhibiting acid-producing microorganisms, a factor that requires further interpretation in conjunction with microbial community and toxicity analyses. In the final Phase 9 (days 515–528), after the reactor HRT was adjusted back to 0.5 days, acetic acid and total SCFA concentrations rapidly recovered, reaching 237.92 mg / L and 278.67 mg / L, respectively, returning to the levels seen at the beginning of Phase IV.

Claims

1. A membrane biofilm reactor, characterized in that The membrane biofilm reactor comprises a biogas high-pressure cylinder (1), a high-pressure gas pressure reducing valve (2), a reactor body (3), a hollow fiber membrane assembly (4), a reactor body water outlet (5), a reactor body water inlet (6), a water inlet device (7), a reflux device (10), a circulating water outlet (11), a circulating water inlet (13), a gas sampling port (14), a reflux device water outlet (15), a liquid sampling port (16), a pH measuring instrument (17), a water outlet liquid sealing device (18) and an atmosphere communication port (19); The reactor body (3) is provided with a reactor body water outlet (5) and a reactor body water inlet (6), and a hollow fiber membrane assembly (4) is provided in the reactor body (3); the biogas high-pressure cylinder (1) is connected to the hollow fiber membrane assembly (4) through a gas pipeline; the water inlet device (7) is connected to the reactor body water inlet (6) through the water inlet pipeline; The reflux device (10) is provided with a circulating water outlet (11), a circulating water inlet (13), a gas sampling port (14), a reflux device water outlet (15) and a liquid sampling port (16); a pH measuring instrument (17) is provided inside the reflux device (10); The reactor body water outlet (5) is connected to the circulating water inlet (13) through a liquid pipeline; the circulating water outlet (11) is connected to the reactor body water inlet (6) through a circulating pipeline; the reflux device water outlet (15) is connected to the interior of the water outlet liquid seal device (18) through the water outlet pipeline; and the water outlet liquid seal device (18) is provided with an atmosphere communication port (19).

2. A membrane biofilm reactor according to claim 1, characterized in that The water inlet device (7) further comprises a first air bag (9), and the first air bag (9) is connected to the interior of the water inlet device (7) via a gas pipeline.

3. A membrane biofilm reactor according to claim 1, characterized in that A water inlet pump (8) is provided on the pipeline connecting the water inlet device (7) and the water inlet (6) of the reactor body.

4. A membrane biofilm reactor according to claim 1, characterized in that A high-pressure gas pressure reducing valve (2) is provided on the gas pipeline connecting the biogas high-pressure gas cylinder (1) and the hollow fiber membrane assembly (4), and the high-pressure gas pressure reducing valve (2) controls the gas flow of the biogas high-pressure gas cylinder (1).

5. A membrane biofilm reactor according to claim 1, characterized in that A circulation pump (12) is provided on the pipeline connecting the circulating water outlet (11) and the water inlet (6) of the reactor body.

6. A membrane biofilm reactor according to claim 1, characterized in that The water outlet liquid sealing device (18) is further provided with a second air bag (20), and the second air bag (20) is connected to the interior of the water outlet liquid sealing device (18) through a gas pipeline.

7. A method for efficiently coupling biogas resource utilization and denitrification, characterized in that The membrane biofilm reactor according to claim 1 is applied, specifically by the following steps:

1. The microbial seed liquid is loaded into the reflux device (10), and the simulated wastewater is loaded into the water inlet device (7); the microbial seed liquid in the reflux device (10) is inoculated into the reactor body (3) through the circulation pump (12), and the simulated wastewater in the water inlet device (7) is then added to the reactor body (3) through the water inlet pump (8). After the simulated wastewater and the microbial seed liquid are fully mixed to obtain a mixed liquid, argon gas with a purity of 99.99% is introduced through the liquid sampling port (16). The purity of 99. The mixed liquid is aerated with 99% argon gas to an anaerobic state, and then the reactor body (3) is sealed; the high-pressure gas pressure reducing valve (2) is opened, and the simulated biogas in the biogas high-pressure gas cylinder (1) enters the hollow fiber membrane assembly (4); the temperature of the reactor body (3) is maintained at room temperature, the speed of the circulation pump (12) is set to 65 mL / min, the speed of the water inlet pump (8) is set to 5 mL / min, and the pressure in the hollow fiber membrane assembly (4) is controlled at 1.25 atm by the high-pressure gas pressure reducing valve (2); The simulated wastewater described in step 1 is composed of KH2PO4, MgSO4·7H2O, CaCl2·2H2O, NH4Cl, acidic trace elements, alkaline trace elements and distilled water, wherein the concentration of KH2PO4 is 0.075 g / L, the concentration of MgSO4·7H2O is 0.2 g / L, the concentration of CaCl2·2H2O is 0.3 g / L, the concentration of NH4Cl is 0.09 g / L, the concentration of acidic trace elements is 0.5 mL / L, and the concentration of alkaline trace elements is 0.2 mL / L; Second, nitrate or nitrite is added to the simulated wastewater, which is then pumped into the reactor body (3) through the water inlet device (7), and then operated in a sequencing batch reactor mode to achieve biogas resource utilization and denitrification processes.

8. The method of efficiently coupling biogas resource utilization and denitrification according to claim 7, characterized in that The acidic trace elements consist of FeSO4·7H2O, CoCl2·6H2O, ZnSO4·7H2O, MnCl2·4H2O, CuSO4·5H2O, NiCl2·6H2O, H3BO4, HCl and distilled water, wherein the concentration of FeSO4·7H2O is 2.085 g / L, the concentration of CoCl2·6H2O is 0.12 g / L, the concentration of ZnSO4·7H2O is 0.068 g / L, the concentration of MnCl2·4H2O is 0.5 g / L, the concentration of CuSO4·5H2O is 0.32 g / L, the concentration of NiCl2·6H2O is 0.095 g / L, the concentration of H3BO4 is 0.014 g / L, and the concentration of HCl is 100 mmol / L.

9. The method of efficiently coupling biogas resource utilization and denitrification according to claim 7, characterized in that The alkaline trace elements are composed of NaOH, Na2WO4·2H2O, KMnO4, SeO2 and distilled water, wherein the concentration of NaOH is 0.4g / L, the concentration of Na2WO4·2H2O is 0.05g / L, the concentration of KMnO4 is 0.242g / L, and the concentration of SeO2 is 0.67g / L.

10. The method of efficiently coupling biogas resource utilization and denitrification according to claim 7, characterized in that The amount of nitrate or nitrite added in step 2 is 200 mg-N / L.

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