A method for removing nitrate from water using a membrane biofilm reactor based on sulfur-hydrogen synergistic denitrification

Abstract

The present invention provides a method for removing nitrate from water by using a membrane biofilm reactor based on sulphur-hydrogen synergistic denitrification, which belongs to the technical field of water purification. When the membrane biofilm based on sulphur-hydrogen synergistic denitrification is used to purify nitrate-containing water bodies, the denitrification activity of the outer biofilm of H2-MBfR can be enhanced, and the denitrification efficiency of the membrane biofilm reactor for NO3 in water bodies can be effectively improved. ‑ Specifically, in view of the problem that the denitrification activity of the outer layer of the biofilm is low or inactive during the operation of the traditional H2-MBfR, the present invention adds a soluble electron donor S2O3 to the influent of the membrane biofilm reactor. 2‑ , to activate the denitrification activity of the outer biofilm, and improve the membrane biofilm reactor's denitrification of NO3 in the water through the synergistic denitrification of sulfur and hydrogen. ‑ The removal performance of H2‑MBfR can be scaled up in engineering, which is of great significance for the secondary development and large-scale promotion and application of H2‑MBfR performance.

Description

Technical Field

[0001] The present invention relates to the technical field of water purification, and in particular to a method for removing nitrate from water using a membrane biofilm reactor based on sulphur-hydrogen synergistic denitrification. Background Art

[0002] Nitrate removal technologies for water bodies can be mainly divided into physical and chemical methods and biochemical methods. Among them, microbial denitrification technology has many advantages such as low operating costs, relatively simple operation and management, and environmental friendliness, and has been widely favored. In recent years, a hydrogen-based membrane biofilm reactor (H2-MBfR) has been developed. It uses hollow fiber membranes to diffuse H2 without bubbles, combined with biofilm autotrophic denitrification technology. It has the characteristics of being clean and non-toxic, requiring no external organic carbon source, generating no secondary pollutants, and leaving no excess sludge. It is considered to be a NO3 removal technology with great development prospects. - Degradation technology.

[0003] However, this technology currently faces a key technical problem in the process of experimental research and engineering practice, namely, water vapor and N2 outside the hollow fiber membrane will diffuse into the hollow fiber membrane cavity due to osmotic pressure (this phenomenon is called reverse diffusion). Some scholars have shown that (Martin KJ et al., Bioresource Technol. , 2012, 122: 83-94; Jiang et al. Water , 2020, 12: 3196), due to the reverse diffusion effect, the H2 partial pressure or concentration in the hollow fiber membrane cavity will gradually decrease with the increase of the distance from the gas supply end, resulting in the non-denitrification active area outside the biofilm gradually expanding with the increase of the gas supply distance. There may be a large number of outer biofilms at the farthest distance from the gas supply end that have no denitrification activity due to the inability to obtain H2, thereby reducing the reactor's ability to remove pollutants. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for removing nitrate from water by using a membrane biofilm reactor based on sulphur-hydrogen synergistic denitrification. When the membrane biofilm based on sulphur-hydrogen synergistic denitrification is used to purify nitrate-containing water bodies, the denitrification activity of the outer biofilm of H2-MBfR can be enhanced, and the denitrification efficiency of the membrane biofilm reactor for NO3 in water bodies can be effectively improved. - removal performance.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for removing nitrate from water using a membrane biofilm reactor based on sulfur-hydrogen coordinated denitrification, comprising the following steps:

[0007] (1) Providing a membrane biofilm reactor; the membrane biofilm reactor includes a raw water tank, a main reaction tank, a secondary reaction tank and a hydrogen cylinder;

[0008] The main reaction tank and the auxiliary reaction tank are placed vertically. The main reaction tank is provided with a first water inlet at the bottom and a first water outlet at the top; the auxiliary reaction tank is provided with a second water inlet at the bottom and a second water outlet at the top; the raw water tank is connected to the first water inlet via a water inlet pipeline, and the main reaction tank is also provided with a drain, the first water outlet is connected to the drain and the second water inlet respectively via a tee; the second water outlet is connected to the first water inlet via an internal circulation reflux pipeline;

[0009] The main reaction tank is provided with a vertically placed first hollow fiber membrane assembly, and the auxiliary reaction tank is provided with a vertically placed second hollow fiber membrane assembly, and the upper and lower ends of the first hollow fiber membrane assembly and the second hollow fiber membrane assembly are connected to the hydrogen cylinder through the gas supply pipeline;

[0010] (2) inoculating sludge into the membrane biofilm reactor, continuously passing acclimation raw water containing nitrate into the membrane biofilm reactor, and simultaneously using a hydrogen cylinder to provide H2, and the mixed liquid in the membrane biofilm reactor is refluxed through a reflux pipeline to acclimate the membrane biofilm reactor, so that a biofilm is formed on the surfaces of the first hollow fiber membrane module and the second hollow fiber membrane module;

[0011] The nitrate-containing raw water is mixed with soluble thiosulfate, and the resulting mixed water body is continuously introduced into the acclimated membrane biofilm reactor, while continuing to use a hydrogen bottle to provide H2. The mixed liquid in the membrane biofilm reactor is refluxed through the reflux pipeline to achieve the removal of nitrate from the nitrate-containing raw water.

[0012] Preferably, the soluble thiosulfate is sodium thiosulfate.

[0013] Preferably, in the process of removing nitrate from the nitrate-containing raw water, the concentration of nitrate in the mixed water obtained by mixing the nitrate-containing raw water with soluble thiosulfate is 10-50 mgN / L, and the concentration of soluble thiosulfate is 10-100 mgS / L.

[0014] Preferably, during the process of removing nitrate from the nitrate-containing raw water, the reflux rate is 50 to 150 times the inlet water flow rate.

[0015] Preferably, during the process of removing nitrate from the nitrate-containing raw water, the partial pressure of H2 is 0.01~0.04MPa.

[0016] Preferably, the thickness of the biofilm is 300-800 μm.

[0017] Preferably, a water inlet pump is also provided on the water inlet pipeline.

[0018] Preferably, a reflux pump is further provided on the internal circulation reflux pipeline.

[0019] Preferably, the first hollow fiber membrane assembly contains 20 to 50 hollow fiber membrane fibers, and the second hollow fiber membrane assembly contains 2 to 5 hollow fiber membrane fibers.

[0020] Preferably, the hollow fiber membrane has a pore size of 0.02-0.2 μm, an inner diameter of 400-500 μm, and an outer diameter of 500-600 μm.

[0021] The present invention provides a method for removing nitrate from water by using a membrane biofilm reactor based on sulphur-hydrogen synergistic denitrification. When the membrane biofilm based on sulphur-hydrogen synergistic denitrification is used to purify nitrate-containing water bodies, the denitrification activity of the outer biofilm of H2-MBfR can be enhanced, effectively improving the denitrification activity of the membrane biofilm reactor on NO3 in water bodies. - Specifically, in view of the problem that the denitrification activity of the outer layer of the biofilm is low or inactive during the operation of the traditional H2-MBfR, the present invention adds a soluble electron donor S2O3 to the influent of the membrane biofilm reactor. 2- , to activate the denitrification activity of the outer biofilm, and improve the membrane biofilm reactor's denitrification of NO3 in the water through the synergistic denitrification of sulfur and hydrogen. - The removal performance can be scaled up in engineering, which is of great significance to the secondary development and large-scale promotion and application of H2-MBfR performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of the membrane biofilm reactor of the present invention; in the figure, 1-raw water tank, 2-water inlet pump, 3-reflux pump, 4-main reaction tank, 5-side reaction tank, 6-hydrogen cylinder, 7-drain port;

[0023] Figure 2 Effect of different concentrations of Na2S2O3 on the removal of NO3 by the medium-film biofilm reactor of the present invention - Performance impact comparison chart. DETAILED DESCRIPTION

[0024] The present invention provides a method for removing nitrate from water using a membrane biofilm reactor based on sulfur-hydrogen coordinated denitrification, comprising the following steps:

[0025] (1) Providing a membrane biofilm reactor; the membrane biofilm reactor includes a raw water tank, a main reaction tank, a secondary reaction tank and a hydrogen cylinder;

[0026] The main reaction tank and the auxiliary reaction tank are placed vertically. The main reaction tank is provided with a first water inlet at the bottom and a first water outlet at the top; the auxiliary reaction tank is provided with a second water inlet at the bottom and a second water outlet at the top; the raw water tank is connected to the first water inlet via a water inlet pipeline, and the main reaction tank is also provided with a drain, the first water outlet is connected to the drain and the second water inlet respectively via a tee; the second water outlet is connected to the first water inlet via an internal circulation reflux pipeline;

[0027] The main reaction tank is provided with a vertically placed first hollow fiber membrane assembly, and the auxiliary reaction tank is provided with a vertically placed second hollow fiber membrane assembly, and the upper and lower ends of the first hollow fiber membrane assembly and the second hollow fiber membrane assembly are connected to the hydrogen cylinder through the gas supply pipeline;

[0028] (2) inoculating sludge into the membrane biofilm reactor, continuously passing acclimation raw water containing nitrate into the membrane biofilm reactor, and simultaneously using a hydrogen cylinder to provide H2, and the mixed liquid in the membrane biofilm reactor is refluxed through a reflux pipeline to acclimate the membrane biofilm reactor, so that a biofilm is formed on the surfaces of the first hollow fiber membrane module and the second hollow fiber membrane module;

[0029] The nitrate-containing raw water is mixed with soluble thiosulfate, and the resulting mixed water body is continuously introduced into the acclimated membrane biofilm reactor, while continuing to use a hydrogen bottle to provide H2. The mixed liquid in the membrane biofilm reactor is refluxed through the reflux pipeline to achieve the removal of nitrate from the nitrate-containing raw water.

[0030] First, the membrane biofilm reactor described in the present invention will be described in detail. The membrane biofilm reactor comprises a raw water tank, a primary reaction tank, a secondary reaction tank, and a hydrogen cylinder. The raw water tank is used to store water delivered to the membrane biofilm reactor. The size and material of the raw water tank are not particularly limited and can be selected based on actual needs.

[0031] In the present invention, the main reaction tank and the auxiliary reaction tank are placed vertically. As an embodiment of the present invention, the main reaction tank is processed from a circular glass tube with an inner diameter of 22 mm and a tube length of 50 cm; the auxiliary reaction tank is processed from a circular glass tube with an inner diameter of 20 mm and a tube length of 50 cm. In the present invention, the main reaction tank is provided with a first water inlet at the bottom and a first water outlet at the top; the auxiliary reaction tank is provided with a second water inlet at the bottom and a second water outlet at the top. In the present invention, the raw water tank is connected to the first water inlet via a water inlet pipeline, and the main reaction tank is also provided with a drain (for discharging water that meets the standards after treatment). The first water outlet is connected to the drain and the second water inlet respectively through a tee, that is, the raw water tank, the main reaction tank and the auxiliary reaction tank are connected in sequence; the second water outlet is connected to the first water inlet via an internal circulation reflux pipeline, that is, the main reaction tank and the auxiliary reaction tank form a circulation loop through the internal circulation reflux pipeline. As an embodiment of the present invention, the water inlet pipeline is further provided with a water inlet pump. As an embodiment of the present invention, the internal circulation return pipeline is further provided with a return pump.

[0032] In the present invention, a first hollow fiber membrane assembly placed vertically is provided in the main reaction tank, and the first hollow fiber membrane assembly preferably contains 20 to 50 hollow fiber membrane threads, more preferably 32. In the present invention, the hollow fiber membrane thread is preferably made of commercially available hydrophobic polypropylene, the membrane pore size is preferably 0.02 to 0.2 μm, the inner diameter is preferably 400 to 500 μm, and the outer diameter is preferably 500 to 600 μm. In the present invention, the two ends of the hollow fiber membrane thread in the first hollow fiber membrane assembly are preferably bonded to the sleeve with epoxy resin glue, and then the sleeve is passed through the upper and lower sealing cover plates of the main reaction tank and fixed to the upper and lower sealing cover plates with epoxy resin glue.

[0033] In the present invention, a second hollow fiber membrane assembly is vertically arranged in the secondary reaction tank, and the second hollow fiber membrane assembly preferably contains 2 to 5 hollow fiber membrane fibers, more preferably 4. In the present invention, the type and fixing method of the hollow fiber membrane fibers in the second hollow fiber membrane assembly are preferably the same as those in the first hollow fiber membrane assembly, and will not be repeated here.

[0034] In the present invention, the hollow fiber membrane assembly in the main reaction tank contains a larger number of hollow fiber membrane filaments, which serves as the main reaction area for pollutant removal; the hollow fiber membrane assembly in the secondary reaction tank contains a smaller number of hollow fiber membrane filaments, which is used for monitoring and sampling of biofilms.

[0035] In the present invention, the upper and lower ends of the first and second hollow fiber membrane assemblies are independently connected to a hydrogen cylinder via a gas supply line. As one embodiment of the present invention, one end of the gas supply line is connected to the hydrogen cylinder, and the other end is divided into two branches, one of which is connected to the upper ends of the first and second hollow fiber membrane assemblies, and the other is connected to the lower ends of the first and second hollow fiber membrane assemblies. As one embodiment of the present invention, the hydrogen cylinder is provided with a pressure dividing valve to adjust the H2 supply pressure to 0.001-0.1 MPa.

[0036] After obtaining a membrane biofilm reactor, the present invention inoculates the membrane biofilm reactor with sludge, continuously introduces nitrate-containing acclimation raw water into the membrane biofilm reactor, and simultaneously uses a hydrogen cylinder to provide H2. The mixed liquid in the membrane biofilm reactor is refluxed through a reflux line to acclimate the membrane biofilm reactor, thereby forming a biofilm on the surfaces of the first and second hollow fiber membrane modules. The present invention first starts and acclimates the membrane biofilm reactor to form a biofilm on the surfaces of the hollow fiber membrane modules in the membrane biofilm reactor and ensure smooth operation of the reactor during the subsequent nitrate removal process.

[0037] The present invention does not specifically limit the source of the sludge, and anoxic sludge from municipal sewage treatment plants, which is well known to those skilled in the art, can be used. In the present invention, the inoculum amount of the sludge is preferably 5-15% of the total effective volume of the membrane biofilm reactor, and more preferably 10%. In the present invention, the raw water for acclimation is preferably supplemented with an inorganic carbon source and a buffer solution on the basis of nitrate-containing raw water, so as to meet the growth of microorganisms and control the pH value of the system within an appropriate range; in the present invention, the inorganic carbon source is preferably NaHCO3, and the buffer solution is preferably a phosphate buffer, specifically a buffer solution prepared with KH2PO4 and Na2HPO4. In an embodiment of the present invention, taking the use of the membrane biofilm reactor to treat nitrate-containing raw water as an example, the components of the acclimation raw water preferably include: 20 mgN / L NaNO3, 80 mg / L NaHCO3, 128 mg / L KH2PO4 and 434 mg / L Na2HPO4; preferably also including trace elements, specifically: 1 mg / L MgCl2·6H2O, 1 mg / L FeSO4·7H2O, 1 mg / L CaCl2·6H2O, 0.013 mg / L ZnSO4·7H2O, 0.038 mg / L H3BO3, 0.001 mg / L CuCl2·2H2O, 0.004 mg / L Na2MoO4·2H2O, 0.004 mg / L MnCl2·4H2O, 0.025 mg / L CoCl2·6H2O, 0.001 mg / L NiCl2·6H2O and 0.004 mg / L Na2SeO3.

[0038] In the present invention, during the startup and acclimation of the membrane biofilm reactor, the partial pressure of H2 is preferably 0.01-0.04 MPa, more preferably 0.02 MPa. In the present invention, during the startup and acclimation of the membrane biofilm reactor, the flow rate of the reflux is preferably 50-150 times the inlet flow rate, more preferably 100 times, so as to achieve the purpose of completely mixing the mixed liquid in the reactor; the present invention preferably uses an inlet pump to continuously pass the acclimation raw water into the main reaction tank through the inlet pipe, the mixed liquid in the main reaction tank enters the secondary reaction tank, and the mixed liquid is refluxed through the reflux pipe by the reflux pump and merged into the inlet pipe; in an embodiment of the present invention, the inlet pump flow rate is preferably 1 mL / min, and the reflux pump flow rate is preferably 100 mL / min.

[0039] In the present invention, the thickness of the biofilm is preferably 300-800 μm, more preferably 600±50 μm. After the biofilm is formed, the present invention preferably monitors the nitrate concentration in the effluent. When the nitrate concentration in the effluent remains stable, the startup and acclimation of the membrane biofilm reactor are considered complete. In an embodiment of the present invention, the startup and acclimation of the membrane biofilm reactor are considered complete when the nitrate concentration in the effluent remains stable for at least 5 consecutive days.

[0040] In the present invention, after the membrane biofilm reactor is started and acclimated, the nitrate-containing raw water is mixed with a soluble thiosulfate, and the resulting mixed water body is continuously passed into the acclimated membrane biofilm reactor, while continuing to use a hydrogen cylinder to provide H2. The mixed liquid in the membrane biofilm reactor is refluxed through the reflux pipeline to achieve the removal of nitrates from the nitrate-containing raw water. In the present invention, the soluble thiosulfate is preferably sodium thiosulfate. In the present invention, during the process of removing nitrates from the nitrate-containing raw water, the concentration of nitrate in the mixed water body obtained by mixing the nitrate-containing raw water and the soluble thiosulfate is preferably 10 to 50 mgN / L, specifically 20 mgN / L; the concentration of soluble thiosulfate is preferably 10 to 100 mgS / L, specifically 22 mgS / L, 46 mgS / L or 68 mgS / L.

[0041] In the present invention, during the process of removing nitrate from the nitrate-containing raw water, the partial pressure of H2 is preferably 0.01 to 0.04 MPa, more preferably 0.02 MPa. In the present invention, during the process of removing nitrate from the nitrate-containing raw water, the reflux rate is 50 to 150 times the inlet flow rate, more preferably 100 times, so as to achieve the purpose of completely mixing the mixed liquid in the reactor; the present invention preferably uses an inlet pump to continuously pass the mixed water obtained by mixing the nitrate-containing raw water and the soluble thiosulfate into the main reaction tank through the inlet pipeline, the mixed water in the main reaction tank enters the secondary reaction tank, and the mixed water is refluxed through the reflux pipeline by a reflux pump and merged into the inlet pipeline; in an embodiment of the present invention, the inlet pump flow rate is preferably 1 mL / min, and the reflux pump flow rate is preferably 100 mL / min.

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example 1

[0043] This example uses a membrane biofilm reactor to degrade nitrate, the most typical oxidizing pollutant in water. The specific steps are as follows:

[0044] (1) According to Figure 1 A membrane biofilm reactor was constructed, wherein the main reaction tank 4 was processed from a circular glass tube with an inner diameter of 22 mm and a tube length of 50 cm. The first hollow fiber membrane assembly in the main reaction tank 4 contained 32 hollow fiber membrane filaments, and the hollow fiber membrane filaments were made of commercially available hydrophobic polypropylene material with a membrane pore size of 0.02~0.2 μm, an inner diameter of 400~500 μm, and an outer diameter of 500~600 μm; the two ends of the first hollow fiber membrane assembly were respectively bonded to the sleeve with epoxy resin glue, and then the sleeve was bonded to the opening on the wall of the main reaction tank 4 with epoxy resin glue to fix the first hollow fiber membrane assembly; the auxiliary reaction tank 5 was processed from a circular glass tube with an inner diameter of 20 mm and a tube length of 50 cm. The second hollow fiber membrane assembly in the auxiliary reaction tank 5 contained 4 hollow fiber membrane filaments, and the specific types, specifications and fixing methods were the same as those of the first hollow fiber membrane assembly.

[0045] (2) Start-up and acclimation of membrane biofilm reactor: 40 mL of anoxic tank sludge from Qilidian Wastewater Treatment Plant in Guilin, Guangxi was inoculated into the membrane biofilm reactor (the inoculation volume was 10% of the total effective volume of the reactor); the first simulated wastewater was prepared, and the components of the first simulated wastewater included: 20 mgN / L NaNO3, 80 mg / L NaHCO3 (as an inorganic carbon source for microbial growth), 128 mg / L KH2PO4 and 434 mg / L Na2HPO4 (as a buffer solution to control the pH value of the system), 1 mg / L MgCl2·6H2O, 1 mg / L FeSO4·7H2O, 1 mg / L CaCl2·6H2O, 0.013 mg / L ZnSO4·7H2O, 0.038 mg / L H3BO3, 0.001 mg / L CuCl2·2H2O, 0.004 0.004 mg / L of Na2MoO4·2H2O, 0.004 mg / L of MnCl2·4H2O, 0.025 mg / L of CoCl2·6H2O, 0.001 mg / L of NiCl2·6H2O, and 0.004 mg / L of Na2SeO3 (to provide trace elements required for microbial growth); start the water inlet pump 2, and let the first simulated wastewater prepared artificially in the raw water tank 1 enter the bottom of the main reaction tank 4 through the water inlet pipe, and set the flow rate of the water inlet pump 2 to 0.63 mL / min; at the same time, start the reflux pump 3, and set the flow rate of the reflux pump 3 to 100 mL / min; and set the supply pressure of the H2 bottle 6 to 0.02 MPa to provide H2 to the hollow fiber membrane components in the main reaction tank 4 and the auxiliary reaction tank 5;

[0046] The membrane biofilm reactor is operated continuously until a stable biofilm (thickness of 600±50 μm) is formed on the surface of the first hollow fiber membrane module and the second hollow fiber membrane module, and water samples are taken from the drainage outlet 7 for testing. When NO3 - When the concentration remains basically unchanged for 5 consecutive days, the start-up and acclimation of the membrane biofilm reactor are considered to be completed; at this time, the NO3 - The concentration was 8.1±0.2 mgN / L, NO3 - The removal rate is 59~61%.

[0047] (3) Add Na2S2O3 to the influent to increase NO3 - Removal rate: prepare a second simulated wastewater, the difference between the second simulated wastewater and the first simulated wastewater is that it contains Na2S2O3 with a concentration of 22 mgS / L; after the membrane biofilm reactor is started and acclimated, the second simulated wastewater is introduced, and the other operating conditions of the membrane biofilm reactor are kept consistent with those in the start-up and acclimation steps, so that sulfur autotrophic denitrifying bacteria are generated in the biofilm, and the membrane biofilm reactor is operated until NO3 - The concentration reached stability. Example 2

[0048] The method of Example 1 was followed, except that the concentration of Na2S2O3 in the influent in step (3) was 46 mgS / L. Example 3

[0049] The method of Example 1 was followed, except that the concentration of Na2S2O3 in the influent in step (3) was 68 mgS / L. Comparative Example 1

[0050] The method of Example 1 was followed, except that no Na2S2O3 was added to the influent water in step (3), i.e., the concentration was 0.

[0051] Figure 2 The effects of different concentrations of Na2S2O3 on the removal of NO3 by the medium-film biofilm reactor of the present invention - The results show that adding different concentrations of Na2S2O3 to the contaminated raw water has a significant effect on the removal of NO3 by the membrane biofilm reactor compared to the case where the membrane biofilm reactor only provides H2 as an electron donor. - The performance of the reactor was improved to varying degrees, indicating that the additional addition of Na2S2O3 resulted in the synergistic denitrification of sulfur and hydrogen in the membrane biofilm reactor. When the concentration of Na2S2O3 increased from 0 mgS / L to 46 mgS / L, the NO3 - The concentration decreased significantly from 8.10 mgN / L to 4.10 mgN / L, and NO3- Removal flux from 1.21gN / m 2 d increases to 1.62 gN / m 2 ·d, corresponding NO3 - The removal rate increased from 60% to 80%; when Na2S2O3 increased from 46 mgS / L to 68 mgS / L, NO3 - The concentration dropped to 3.1 mgN / L, NO3 - The removal rate was further increased by about 4.5%. The above results show that adding a certain concentration of Na2S2O3 as a soluble electron donor to H2-MBfR can significantly improve the reactor's ability to remove NO3 - performance.

[0052] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for removing nitrate from water using a membrane biofilm reactor based on sulfur-hydrogen synergistic denitrification, comprising the following steps: (1) Providing a membrane biofilm reactor; the membrane biofilm reactor includes a raw water tank, a main reaction tank, a secondary reaction tank and a hydrogen cylinder; The main reaction tank and the auxiliary reaction tank are placed vertically. The main reaction tank is provided with a first water inlet at the bottom and a first water outlet at the top; the auxiliary reaction tank is provided with a second water inlet at the bottom and a second water outlet at the top; the raw water tank is connected to the first water inlet via a water inlet pipeline, and the main reaction tank is also provided with a drain, the first water outlet is connected to the drain and the second water inlet respectively via a tee; the second water outlet is connected to the first water inlet via an internal circulation reflux pipeline; The main reaction tank is provided with a vertically placed first hollow fiber membrane assembly, and the auxiliary reaction tank is provided with a vertically placed second hollow fiber membrane assembly, and the upper and lower ends of the first hollow fiber membrane assembly and the second hollow fiber membrane assembly are connected to the hydrogen cylinder through the gas supply pipeline; (2) inoculating sludge into the membrane biofilm reactor, continuously passing acclimation raw water containing nitrate into the membrane biofilm reactor, and simultaneously using a hydrogen cylinder to provide H2, and the mixed liquid in the membrane biofilm reactor is refluxed through a reflux pipeline to acclimate the membrane biofilm reactor, so that a biofilm is formed on the surfaces of the first hollow fiber membrane module and the second hollow fiber membrane module; The nitrate-containing raw water is mixed with soluble thiosulfate, and the resulting mixed water body is continuously introduced into the acclimated membrane biofilm reactor, while continuing to use a hydrogen bottle to provide H2. The mixed liquid in the membrane biofilm reactor is refluxed through the reflux pipeline to achieve the removal of nitrate from the nitrate-containing raw water.

2. The method according to claim 1, characterized in that The soluble thiosulfate is sodium thiosulfate.

3. The method according to claim 1 or 2, characterized in that In the process of removing nitrate from the nitrate-containing raw water, the concentration of nitrate in the mixed water obtained by mixing the nitrate-containing raw water with soluble thiosulfate is 10-50 mgN / L, and the concentration of soluble thiosulfate is 10-100 mgS / L.

4. The method according to claim 1, wherein During the process of removing nitrate from the nitrate-containing raw water, the reflux rate is 50 to 150 times the inlet water flow rate.

5. The method according to claim 1, wherein During the process of removing nitrate from the nitrate-containing raw water, the partial pressure of H2 is 0.01~0.04 MPa.

6. The method according to claim 1, characterized in that The thickness of the biofilm is 300-800 μm.

7. The method according to claim 1, characterized in that The water inlet pipeline is also provided with a water inlet pump.

8. The method according to claim 1, characterized in that A reflux pump is also provided on the inner circulation reflux pipeline.

9. The method according to claim 1, characterized in that The first hollow fiber membrane assembly contains 20 to 50 hollow fiber membrane fibers, and the second hollow fiber membrane assembly contains 2 to 5 hollow fiber membrane fibers.

10. The method according to claim 9, characterized in that The hollow fiber membrane has a pore size of 0.02-0.2 μm, an inner diameter of 400-500 μm, and an outer diameter of 500-600 μm.

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