Low-temperature efficient denitrification method for regulating electron donor to drive sulfur autotrophic denitrification

Abstract

The invention belongs to the technical field of sewage treatment biological denitrification, and particularly relates to a low-temperature efficient denitrification method for regulating and controlling electron donors to drive sulfur autotrophic denitrification. The method comprises the following steps: inoculating seed sludge into a sequencing batch bio-membrane reactor, and sequentially performing heterotrophic denitrification domestication treatment, mixed denitrification domestication treatment and sulfur autotrophic denitrification domestication treatment at the environment temperature of 25-27 DEG C by regulating and controlling the variety and concentration of electron donors (carbon sources and / or sulfur sources), so as to start a sulfur autotrophic denitrification nitrogen removal system; on the basis of the started sulfur autotrophic denitrification nitrogen removal system, the environment temperature for optimizing domestication treatment is 13-15 DEG C, the sulfur autotrophic denitrification efficient nitrogen removal system suitable for the low-temperature environment is obtained, and the total nitrogen removal rate of the system is maintained to be 97% or above after continuous 62 days. The method is suitable for various nitrogen-containing sewage treatment scenes, has remarkable application value in sewage treatment in low-temperature regions or low-temperature seasons, and provides a new technical approach for efficient, economic and sustainable development of sewage treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of biological nitrogen removal from sewage, and more specifically relates to a low-temperature and highly efficient nitrogen removal method for regulating sulfur autotrophic denitrification driven by an electron donor. Background Art

[0002] The removal of nitrogen-containing pollutants in sewage has become an important topic in the field of sewage treatment. Traditional biological nitrogen removal processes mainly rely on heterotrophic denitrification, that is, using organic carbon sources as electron donors to reduce nitrate to nitrogen gas. However, this method has some limitations, such as the need for a large amount of externally added carbon sources, which increases the operating cost and carbon emissions. The additional addition of carbon sources (such as methanol) during heterotrophic denitrification will significantly increase the economic cost and may cause secondary pollution problems. In addition, during heterotrophic denitrification, the decomposition of externally added carbon sources will release carbon dioxide, further exacerbating greenhouse gas emissions. At low temperatures, the activity of heterotrophic denitrifying microorganisms is significantly reduced, resulting in a substantial decline in nitrogen removal efficiency. Especially in winter or cold regions, traditional heterotrophic denitrification processes are difficult to maintain efficient operation, increasing the difficulty and cost of sewage treatment. Therefore, developing a biological nitrogen removal technology that can efficiently remove nitrogen at low temperatures is of great significance for improving the economic efficiency and environmental sustainability of sewage treatment.

[0003] Sulfur autotrophic denitrification is an emerging biological nitrogen removal technology that uses inorganic sulfur compounds such as sulfide as electron donors to reduce nitrate to nitrogen gas under anoxic conditions. Compared with traditional heterotrophic denitrification, sulfur autotrophic denitrification has significant advantages. First of all, sulfur autotrophic denitrification does not require externally added organic carbon sources, thereby reducing the operating cost and avoiding carbon dioxide emissions generated by the decomposition of carbon sources. It is a green and low-carbon biological nitrogen removal technology. The sulfur sources used in sulfur autotrophic denitrification include S 2- 、S 0 、S2O3 2- . Secondly, the biomass of sulfur autotrophic denitrification is less than that of heterotrophic denitrification. Therefore, using a sulfur autotrophic denitrification system can also reduce the cost of subsequent sludge treatment.

[0004] However, sulfur autotrophic denitrification technology still faces some challenges in practical applications. Compared with traditional heterotrophic denitrification, the influent water of sulfur autotrophic denitrification does not contain carbon sources, resulting in the difficulty of survival of heterotrophic microorganisms, a single microbial community structure, and poor resistance to environmental changes. Therefore, in order to achieve the stable start-up of a sulfur autotrophic denitrification system, how to achieve a smooth transition from traditional heterotrophic denitrification to sulfur autotrophic denitrification and be suitable for efficient nitrogen removal under low-temperature environments has become a problem that needs to be overcome.

[0005] Therefore, how to provide a technology that can efficiently start a sulfur autotrophic denitrification system and maintain a high nitrogen removal efficiency under low-temperature environments has become a difficult problem that needs to be overcome in this field. Summary of the Invention

[0006] The object of the present invention is to provide a low-temperature and highly efficient denitrification method for regulating electron donor-driven sulfur autotrophic denitrification. By regulating the types and concentrations of electron donors, the present invention realizes the stable start-up of sulfur autotrophic denitrification and maintains stable and efficient denitrification performance under low-temperature conditions, providing a new technical solution for the sewage treatment field to solve the problems existing in the above-mentioned prior art.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] One of the technical solutions of the present invention: Provide a low-temperature and highly efficient denitrification method for regulating electron donor-driven sulfur autotrophic denitrification, and the steps include:

[0009] Inoculate the seed sludge into a biofilm reactor, maintain an anaerobic environment in the reactor, and achieve low-temperature and highly efficient denitrification of the sulfur autotrophic denitrification system by regulating the types and concentrations of electron donors and the acclimation temperature;

[0010] The electron donor includes a carbon source and / or a sulfur source;

[0011] The steps for achieving low-temperature and highly efficient denitrification of the sulfur autotrophic denitrification system include: first, perform heterotrophic denitrification acclimation treatment with a carbon source, then perform mixed denitrification acclimation treatment with a carbon source and a sulfur source, then perform sulfur autotrophic denitrification acclimation treatment with a sulfur source, and finally perform low-temperature acclimation to obtain a low-temperature and highly efficient denitrification system for the sulfur autotrophic denitrification system;

[0012] Use the low-temperature and highly efficient denitrification system of the sulfur autotrophic denitrification system for denitrification treatment under low-temperature conditions; the low temperature is 13-15°C.

[0013] The present invention gradually guides the microbial community to transform from heterotrophic denitrification to sulfur autotrophic denitrification by regulating the concentrations of the carbon source and sulfur source in the influent in stages.

[0014] In the heterotrophic denitrification stage, denitrifying bacteria use a carbon source as an electron donor and NO3 - -N as an electron acceptor to reduce NO3 - -N to N2.

[0015] In the mixed denitrification stage, denitrifying bacteria use a carbon source and a sulfur source as electron donors simultaneously and NO3 - -N as an electron acceptor to reduce NO3 - -N to N2.

[0016] In the sulfur autotrophic denitrification stage, denitrifying bacteria use a sulfur source as an electron donor and NO3 - -N as an electron acceptor to reduce NO3 - -N to N2.

[0017] Furthermore, in the low-temperature and high-efficiency denitrification method, the dissolved oxygen concentration in the anaerobic environment maintained by the reactor is less than 0.02 mg / L, the hydraulic retention time (HRT) is 4 ± 0.5 h, and the ambient temperature is 25 - 27 °C.

[0018] Furthermore, the carbon source includes at least one of sodium acetate, glucose, methanol, and sodium citrate.

[0019] Furthermore, the sulfur source includes at least one of sodium thiosulfate, sulfide, and elemental sulfur.

[0020] Furthermore, the steps of the heterotrophic denitrification domestication treatment include: using the carbon source as the electron donor, setting the influent parameters of the reactor as C / N = 5 and S / N = 0, and conducting the heterotrophic denitrification domestication treatment. When the total nitrogen (TN) removal rate is stable above 97%, the heterotrophic denitrification domestication treatment is completed.

[0021] When the total nitrogen (TN) removal rate is stable above 97%, it indicates that the heterotrophic denitrification system has been successfully started.

[0022] Optionally, the parameters of the influent specifically include 60 ± 5 mg / L of NO3 - -N and 300 ± 25 mg / L of COD.

[0023] Furthermore, the mixed denitrification domestication treatment includes: after the heterotrophic denitrification domestication treatment is completed, using both the carbon source and the sulfur source as electron donors, setting the influent parameters of the reactor as C / N = 1.67 and S / N = 3.9, and conducting the mixed denitrification domestication treatment. When the total nitrogen (TN) removal rate is stable above 98%, the mixed denitrification domestication treatment is completed.

[0024] Optionally, the parameters of the influent specifically include 60 ± 5 mg / L of NO3 - -N, 100 ± 8 mg / L of COD, and 234 ± 20 mg / L of S2O3 2- -S.

[0025] When the total nitrogen (TN) removal rate is stable above 98%, it indicates that the microbial community has gradually adapted to the environment with the sulfur source as the electron donor, and the system has successfully transitioned to the mixed denitrification stage.

[0026] Furthermore, the sulfur autotrophic denitrification domestication treatment includes: after the mixed denitrification domestication treatment is completed, using the sulfur source as the electron donor, setting the influent parameters of the reactor as C / N = 0 and S / N = 5, and conducting the sulfur autotrophic denitrification domestication treatment. When the total nitrogen (TN) removal rate is stable above 94%, the sulfur autotrophic denitrification domestication treatment is completed.

[0027] Optionally, the parameters of the influent water specifically include 60±5 mg / L of NO3 - -N, 300±25 mg / L of S2O3 2- -S.

[0028] When the total nitrogen (TN) removal rate is stable above 94%, it indicates that the sulfur autotrophic denitrification system is successfully started and has efficient nitrogen removal ability.

[0029] Further, the low-temperature acclimation step includes:

[0030] Adjust the environmental temperature of the reactor to 13-15 °C, set the influent water parameters of the reactor as C / N = 0, S / N = 5. When the total nitrogen removal rate is stable above 97%, complete the low-temperature acclimation and start to obtain a sulfur autotrophic denitrification high-efficiency nitrogen removal system suitable for low-temperature environment.

[0031] Optionally, the parameters of the influent water specifically include 60±5 mg / L of NO3 - -N, 300±25 mg / L of S2O3 2- -S.

[0032] Based on the successfully started sulfur autotrophic denitrification system above, the present invention further conducts low-temperature acclimation treatment to obtain a denitrification high-efficiency nitrogen removal system suitable for low-temperature environment, which can still maintain high-efficiency nitrogen removal efficiency at low temperature (13-15 degrees Celsius).

[0033] The second technical solution of the present invention: Provide an application of the above low-temperature high-efficiency nitrogen removal method in sewage treatment.

[0034] The third technical solution of the present invention: Provide a method for starting a sulfur autotrophic denitrification nitrogen removal system by regulating electron donors, and the steps include:

[0035] Inoculate the seed sludge into the biofilm reactor, maintain the anaerobic environment in the reactor, and start the sulfur autotrophic denitrification system available for low-temperature high-efficiency nitrogen removal by regulating the types and concentrations of electron donors and the acclimation temperature;

[0036] The electron donors include carbon sources and / or sulfur sources;

[0037] The starting steps of the sulfur autotrophic denitrification system available for low-temperature high-efficiency nitrogen removal include: first, conduct heterotrophic denitrification acclimation treatment with carbon sources, then conduct mixed denitrification acclimation treatment with carbon sources and sulfur sources, then conduct sulfur autotrophic denitrification acclimation treatment with sulfur sources, and finally conduct low-temperature acclimation to obtain a low-temperature high-efficiency nitrogen removal system of the sulfur autotrophic denitrification system; the low temperature is 13-15 °C.

[0038] Further, in the startup method, the dissolved oxygen concentration in the anaerobic environment maintained by the reactor is less than 0.02 mg / L, the hydraulic retention time (HRT) is 4 ± 0.5 h, and the ambient temperature is 25 - 27 °C.

[0039] Further, the carbon source includes at least one of sodium acetate, glucose, methanol, and sodium citrate.

[0040] Further, the sulfur source includes at least one of sodium thiosulfate, sulfide, and elemental sulfur.

[0041] Further, the steps of the heterotrophic denitrification domestication treatment include: using the carbon source as an electron donor, setting the influent parameters of the reactor as C / N = 5, S / N = 0, and performing heterotrophic denitrification domestication treatment. When the total nitrogen (TN) removal rate is stable above 97%, the heterotrophic denitrification domestication treatment is completed.

[0042] When the total nitrogen (TN) removal rate is stable above 97%, it indicates that the heterotrophic denitrification system has been successfully started.

[0043] Optionally, the parameters of the influent specifically include 60 ± 5 mg / L of NO3 - -N and 300 ± 25 mg / L of COD.

[0044] Further, the mixed denitrification domestication treatment includes: after the heterotrophic denitrification domestication treatment is completed, using both the carbon source and the sulfur source as electron donors, setting the influent parameters of the reactor as C / N = 1.67, S / N = 3.9, and performing mixed denitrification domestication treatment. When the total nitrogen (TN) removal rate is stable above 98%, the mixed denitrification domestication treatment is completed.

[0045] Optionally, the parameters of the influent specifically include 60 ± 5 mg / L of NO3 - -N, 100 ± 8 mg / L of COD, and 234 ± 20 mg / L of S2O3 2- -S.

[0046] When the total nitrogen (TN) removal rate is stable above 98%, it indicates that the microbial community has gradually adapted to the environment with the sulfur source as an electron donor, and the system has successfully transitioned to the mixed denitrification stage.

[0047] Further, the sulfur autotrophic denitrification domestication treatment includes: after the mixed denitrification domestication treatment is completed, using the sulfur source as an electron donor, setting the influent parameters of the reactor as C / N = 0, S / N = 5, and performing sulfur autotrophic denitrification domestication treatment. When the total nitrogen (TN) removal rate is stable above 94%, the sulfur autotrophic denitrification domestication treatment is completed.

[0048] Optionally, the parameters of the influent water specifically include 60±5 mg / L of NO3 - -N, 300±25 mg / L of S2O3 2- -S.

[0049] When the total nitrogen (TN) removal rate is stable above 94%, it indicates that the sulfur autotrophic denitrification system is successfully started and has efficient nitrogen removal ability.

[0050] Further, the low-temperature acclimation step includes:

[0051] Adjust the environmental temperature of the reactor to 13-15°C, set the influent water parameters of the reactor as C / N = 0, S / N = 5. When the total nitrogen removal rate is stable above 97%, complete the low-temperature acclimation and start to obtain an efficient sulfur autotrophic denitrification nitrogen removal system suitable for low-temperature environments.

[0052] Optionally, the parameters of the influent water specifically include 60±5 mg / L of NO3 - -N, 300±25 mg / L of S2O3 2- -S.

[0053] The present invention discloses the following technical effects:

[0054] The present invention realizes a smooth transition from traditional heterotrophic denitrification to sulfur autotrophic denitrification by precisely regulating the types and concentrations of electron donors in stages, solves the problem of difficult start-up of traditional sulfur autotrophic denitrification systems, and through further acclimation treatment, obtains an efficient denitrification nitrogen removal system suitable for low-temperature environments, which can still maintain high-efficient nitrogen removal performance in low-temperature environments (13-15°C), breaks through the limitations of traditional biological nitrogen removal technologies under low-temperature conditions, and provides an economic, environmentally friendly and stable technical solution for the sewage treatment field.

[0055] The sulfur autotrophic denitrification provided by the present invention does not require external organic carbon sources, reduces the operating cost and carbon emissions, reduces the dependence on chemical agents, has significant environmental benefits, improves the system shock resistance and stability by precisely regulating electron donors and reaction conditions and optimizing the microbial community structure, and makes it more suitable for the application of actual sewage treatment projects.

[0056] The present invention is applicable to various nitrogen-containing sewage treatment scenarios, especially has significant application value in sewage treatment in low-temperature regions or low-temperature seasons, and provides a new technical approach for realizing the efficient, economic and sustainable development of sewage treatment. Description of the Drawings

[0057] The accompanying drawings, which form a part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0058] Figure 1 For Example 1, the change in the denitrification effect during the startup process of regulating the electron donor-driven sulfur autotrophic denitrification nitrogen removal system.

[0059] Figure 2 For the denitrification effect of the sulfur autotrophic denitrification system under low-temperature environment. Detailed Description of the Invention

[0060] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation to the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0061] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0062] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0063] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the present invention specification are obvious to those skilled in the art. The present invention specification and embodiments are only exemplary.

[0064] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0065] It should be noted that the aspects not described in detail in the present invention are all conventional operation means in the art and are not the focus of the present invention.

[0066] In the specific implementation of the present invention, the reactor used is a Sequencing Batch Biofilm Reactor (SBBR), with a reactor volume of 5 L, the filler is polyurethane sponge, the filler volume ratio is 20%, the reactor always maintains an anaerobic environment, the dissolved oxygen concentration is less than 0.02 mg / L, and the hydraulic retention time (HRT) is 4 ± 0.5 hours.

[0067] The seed sludge used in the specific implementation of the present invention is sourced from the aeration tank of a sewage treatment plant in Beijing.

[0068] The raw materials and reagents used in the specific implementation of the present invention are all commercially available products.

[0069] The carbon source used in the specific implementation of the present invention can be sodium acetate, glucose, methanol or sodium citrate, taking sodium acetate as an example; the sulfur source used can be sodium thiosulfate, sulfide or elemental sulfur, taking sodium thiosulfate as an example.

[0070] Example 1

[0071] The method for starting the sulfur autotrophic denitrification nitrogen removal system by regulating the electron donor includes:

[0072] S1. Inoculate the seed sludge (MLSS is 3000 ± 100 mg / L) into the Sequencing Batch Biofilm Reactor, set the reactor environmental temperature between 25 - 27 °C, use sodium acetate as the carbon source, and set the influent carbon-nitrogen ratio (C / N) to 5. The specific influent indexes are: 60 ± 5 mg / L NO3 - -N, 300 ± 25 mg / L COD. When the total nitrogen (TN) removal rate is stable above 97%, it indicates that the heterotrophic denitrification system is successfully started;

[0073] S2. Use sodium acetate as the carbon source and sodium thiosulfate as the sulfur source, set the influent carbon-nitrogen ratio (C / N) to 1.67 and the sulfur-nitrogen ratio (S / N) to 3.9. The specific influent indexes are 60 ± 5 mg / L of NO3 - -N, 100 ± 8 mg / L of COD and 234 ± 20 mg / L of S2O3 2— S. When the TN removal rate is stable above 98%, it successfully transitions to the mixed denitrification stage;

[0074] S3. Completely remove the carbon source and use only the sulfur source (sodium thiosulfate) as the electron donor. Set the influent sulfur-nitrogen ratio (S / N) to 5. The specific influent indexes are 60 mg / L of NO3 - -N, 300 mg / L of S2O3 2- -S. When the TN removal rate is stable above 94%, the sulfur autotrophic denitrification system is successfully started.

[0075] Figure 1To implement the denitrification effect change during the start-up process of the sulfur autotrophic denitrification system driven by regulating the electron donor in Example 1. As can be seen from the figure, during the 29 days of heterotrophic denitrification acclimation treatment, the total nitrogen (TN) removal rate remained stable above 97% for 29 consecutive days, indicating the successful start-up of the heterotrophic denitrification system; during the 47 days of the mixed denitrification acclimation treatment (days 30-76 in the figure), the TN removal rate from the 17th day (day 46 in the figure) to the 47th day (day 76 in the figure) remained stable above 98% for 30 consecutive days, and the microbial community had gradually adapted to the environment with sulfur source as the electron donor, and the system successfully transitioned to the mixed denitrification stage; during the 20 days of the sulfur autotrophic denitrification acclimation treatment (days 77-96 in the figure), the TN removal rate from the 1st day (day 77 in the figure) to the 20th day (day 96 in the figure) remained stable above 94% for 19 consecutive days, and the sulfur autotrophic denitrification system was successfully started and had efficient denitrification ability.

[0076] Example 2

[0077] Low-temperature and high-efficiency denitrification steps of the sulfur autotrophic denitrification system:

[0078] Based on the sulfur autotrophic denitrification system started in Example 1, adjust the environmental temperature of the reactor to between 13-15 °C, set the influent C / N = 0, S / N = 5, and the specific influent indexes are 60 mg / L of NO3 - -N, 300 mg / L of S2O3 2- -S, and the TN removal rate remained stable above 97%, achieving low-temperature and high-efficiency denitrification of the sulfur autotrophic denitrification system.

[0079] Figure 2 For the denitrification effect of the sulfur autotrophic denitrification system in a low-temperature environment. As can be seen from the figure, during the 102 days of operation, the TN removal rate from the 40th day to the 102nd day remained stable above 97% for 62 consecutive days, indicating the successful start-up of the high-efficiency denitrification system of sulfur autotrophic denitrification in a low-temperature environment, and it can still maintain high-efficiency denitrification performance in a low-temperature environment. Specifically: under the low-temperature condition of 13-15 °C, the system operated for 102 days. Due to the sudden drop in temperature, the TN removal rate fluctuated greatly in the first 50 days, and the TN removal rate on the 16th day was only 5.15%. On the 51st day, the TN removal rate of the system recovered successfully and remained stable above 97%, indicating that the sulfur autotrophic denitrification system can still maintain high-efficiency denitrification performance in a low-temperature environment, which is related to the stable start-up of sulfur autotrophic denitrification by regulating the electron donor in the early stage.

[0080] From the content of Example 1 and Example 2, it can be seen that the low-temperature and highly efficient nitrogen removal method for regulating electron donor-driven sulfur autotrophic denitrification provided by the present invention can effectively solve the problems of low nitrogen removal efficiency, high operating cost, and poor system stability of existing biological nitrogen removal technologies in low-temperature environments. By regulating the types and concentrations of electron donors in stages, the present invention realizes a smooth transition from traditional heterotrophic denitrification to sulfur autotrophic denitrification, and maintains high-efficient nitrogen removal performance under low-temperature conditions, providing an economical, environmentally friendly and stable technical solution for the sewage treatment field.

[0081] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same and similar parts among the various embodiments, reference can be made to each other.

[0082] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A low-temperature and high-efficiency denitrification method for regulating electron donors to drive sulfur autotrophic denitrification, characterized in that the steps include: The seed sludge is inoculated into the biofilm reactor, which maintains an anaerobic environment, and the type and concentration of the electron donor and the acclimation temperature are adjusted to achieve low-temperature and efficient denitrification of the sulfur autotrophic denitrification system; The electron donor includes a carbon source and / or a sulfur source; The step of realizing low-temperature and high-efficiency denitrification of the sulfur autotrophic denitrification system comprises: The ambient temperature of the reactor is set to 25-27°C, a carbon source is used as an electron donor, and the water inlet parameters of the reactor are set to C / N=5, S / N=0, and heterotrophic denitrification acclimation treatment is performed. When the total nitrogen removal rate is stabilized at more than 97%, the carbon source and the sulfur source are used as electron donors, and the water inlet parameters of the reactor are set to C / N=1.67, S / N=3.9, and mixed denitrification acclimation treatment is performed. When the total nitrogen removal rate is stabilized at more than 98%, the sulfur source is used as an electron donor, and the water inlet parameters of the reactor are set to C / N=0, S / N=5, and sulfur autotrophic denitrification acclimation treatment is performed. When the total nitrogen removal rate is stabilized at more than 94%, the ambient temperature of the reactor is adjusted to 13-15°C, and the water inlet parameters of the reactor are set to C / N=0, S / N=5. When the total nitrogen removal rate is stabilized at more than 97%, a low-temperature and high-efficiency denitrification system of a sulfur autotrophic denitrification system is obtained; The low-temperature and high-efficiency denitrification system of the sulfur autotrophic denitrification system is used for denitrification treatment under low-temperature conditions; the low temperature is 13-15°C.

2. The low-temperature and high-efficiency denitrification method according to claim 1, characterized in that: The carbon source includes at least one of sodium acetate, glucose, methanol and sodium citrate; and / or the sulfur source includes at least one of sodium thiosulfate, sulfide and elemental sulfur.

3. Application of the low-temperature and high-efficiency denitrification method according to claim 1 or 2 in sewage treatment.

4. A method for starting a sulfur autotrophic denitrification system driven by regulating electron donors, characterized in that the steps include: The seed sludge is inoculated into the biofilm reactor, the reactor maintains an anaerobic environment, and the sulfur autotrophic denitrification system that can be used for low-temperature and efficient nitrogen removal is started by regulating the type and concentration of electron donors and the acclimation temperature; The electron donor includes a carbon source and / or a sulfur source; The startup steps of the sulfur autotrophic denitrification system for low-temperature and efficient nitrogen removal include: firstly using a carbon source to perform heterotrophic denitrification acclimation treatment, then using a carbon source and a sulfur source to perform mixed denitrification acclimation treatment, then using a sulfur source to perform sulfur autotrophic denitrification acclimation treatment, and finally performing low-temperature acclimation to obtain a low-temperature and efficient nitrogen removal system of the sulfur autotrophic denitrification system; the low temperature is 13-15°C.

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