Device and method for regulating biological membrane niche to realize simultaneous methanogenesis and denitrification

Abstract

The application provides a device and method for regulating biological membrane niche to realize simultaneous methanogenesis and denitrification, and belongs to the technical field of water treatment, comprising a biological membrane reactor, a water distribution tank, a peristaltic pump, an aeration system and an electric stirrer, the biological membrane reactor is filled with biological membrane carriers, and an anoxic-anaerobic biological membrane layered structure can be formed inside the carriers. The application inoculates functional sludge, domesticates the biological membrane carriers, regulates aeration intensity to build a dissolved oxygen gradient, combines with microelectrode real-time monitoring of the dissolved oxygen and oxidation-reduction potential profile inside the carriers, realizes efficient cooperation of denitrifying bacteria and methanogenic bacteria in the same biological membrane reactor, integrates anaerobic digestion and denitrification process, has the advantages of low energy consumption, small land occupation and strong impact resistance, can simultaneously realize organic matter degradation and denitrification of high-concentration organic wastewater, optimizes carbon source utilization efficiency, reduces treatment cost, is suitable for treatment of various high-concentration organic wastewater, and has important theoretical innovation value and engineering application prospect.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and in particular relates to a device and method for regulating the ecological niche of biofilm to achieve simultaneous methane production and denitrification. Background Technology

[0002] High-concentration organic wastewater (such as food wastewater, aquaculture wastewater, and kitchen wastewater) is characterized by high carbon, high nitrogen, and high content of recalcitrant organic matter, posing a significant challenge to current water pollution control. Traditional biological treatment methods often employ a three-stage process (A / A / O), where wastewater undergoes anaerobic biological treatment followed by anoxic and aerobic biological treatment, with the wastewater from the aerobic stage being recycled back to the anoxic stage. However, this process suffers from limitations such as a long flow path, low treatment efficiency, and unreasonable carbon source allocation and utilization. Under the impact of high-concentration organic wastewater quality and quantity, biomass, biological activity, and treatment efficiency need to be improved.

[0003] In response to the current state of high-concentration organic wastewater treatment, there is an urgent need to develop efficient short-process biological treatment technologies to overcome the challenges of existing biological treatment methods, such as large land area requirements, low organic load rates, and poor shock resistance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a device and method for regulating the ecological niche of biofilm to achieve simultaneous methane production and denitrification, realizing the efficient synergistic operation of anaerobic digestion and denitrification in the same biofilm reaction system, and improving the efficiency of organic matter degradation and nitrogen removal in high-concentration organic wastewater.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a device for regulating the ecological niche of biofilm to achieve simultaneous methane production and denitrification, comprising a biofilm reactor, wherein an inlet is provided on the side wall of the biofilm reactor, and an outlet is provided on the top of the biofilm reactor, the outlet being connected to a collection tank, and the inlet being connected to a water distribution tank via a peristaltic pump for continuous or intermittent water intake, the water distribution tank being used to store wastewater to be treated; the biofilm reactor is provided with several biofilm carriers, the biofilm carriers being polyurethane sponge cubes or suspended packing with a certain three-dimensional spatial structure and sufficient porosity, ensuring that the biofilm carriers form an anoxic and anaerobic biofilm stratified structure from the outside to the inside during operation; an aeration disc is installed at the bottom of the biofilm reactor, the aeration disc being connected to an external aeration pump and a gas flow meter via pipelines.

[0006] Furthermore, the water outlet is configured to discharge water via overflow.

[0007] Furthermore, the average residence time (hydraulic residence time) required for the wastewater to complete the biochemical reaction in the biofilm reactor is 6~48h.

[0008] Furthermore, the biofilm carrier occupies 20% to 50% of the effective volume of the biofilm reactor.

[0009] Furthermore, the biofilm carrier may be a polyurethane sponge.

[0010] Furthermore, the biofilm carrier is a cube with a side length of 1-2 cm; the density of the biofilm carrier is 20-40 kg / m³. 3 Furthermore, the pore size of the biofilm carrier is 30~60 PPI.

[0011] Furthermore, the biofilm carrier comprises an inner layer, a middle layer, and an outer layer. The inner layer is an anaerobic zone, the middle layer is an anoxic zone, and the outer layer is a diffusion layer. Methanogenic bacteria reside in the anaerobic zone, and denitrifying bacteria reside in the anoxic zone. By controlling the dissolved oxygen concentration of the solution within the biofilm reactor, and utilizing the diffusion limitation of oxygen within the biofilm carrier, a dissolved oxygen gradient is formed from the surface inwards. The middle layer has relatively high dissolved oxygen, forming an anoxic zone dominated by denitrifying bacteria; while the inner layer, where oxygen diffusion is difficult, forms a strictly anaerobic zone dominated by methanogenic bacteria. By controlling this gradient, the relative ratio of the anoxic to anaerobic zones within the biofilm carrier can be precisely controlled.

[0012] Furthermore, the aeration disc employs a microporous aeration head to supply oxygen to the biofilm reactor, ensuring that the dissolved oxygen content remains within a preset range to guarantee the generation of fine bubbles and uniform oxygen supply; the gas flow meter is used to control the flow rate of gas entering the aeration disc, ensuring the formation of anoxic and anaerobic stratified environments on the biofilm carrier.

[0013] Furthermore, an electric stirrer is installed on the top of the biofilm reactor. The stirring paddle of the electric stirrer extends into the biofilm reactor to slowly stir, keeping the biofilm carrier in a suspended flow state, ensuring uniform mass transfer and preventing the biofilm carrier from accumulating, while avoiding excessive shear force that could damage the biofilm carrier.

[0014] Another objective of this invention is to provide a method for regulating biofilm niches to achieve simultaneous methanogenesis and denitrification, comprising the following steps:

[0015] S1. Inoculate the biofilm reactor with mixed sludge taken from the anaerobic digester and denitrification tank, or acclimated sludge containing methanogenic bacteria and denitrifying bacteria.

[0016] S2. Start the peristaltic pump and continuously feed the high-concentration organic wastewater after nitrification into the biofilm reactor as raw water for acclimatization to acclimatize the biofilm carrier.

[0017] S3. In the early stage of acclimatization, the aeration rate is controlled by the aeration pump and gas flow meter to maintain the dissolved oxygen (DO) in the biofilm reactor at a low level. The acclimatization process lasts for several weeks until a biofilm is formed on the surface and internal pores of the biofilm carrier.

[0018] S4. Formation and Regulation of Layered Structure of Biomembrane Carriers:

[0019] By controlling the aeration intensity using a gas flow meter and utilizing the diffusion limitation of oxygen within the biofilm carrier, the penetration depth of oxygen into the biofilm carrier is controlled, naturally forming a dissolved oxygen gradient from the surface to the interior. The middle layer of the biofilm carrier has a relatively high dissolved oxygen concentration, forming an anoxic zone dominated by denitrifying bacteria. The inner layer of the biofilm carrier has an extremely low or even zero dissolved oxygen concentration, forming a strictly anaerobic zone dominated by methanogenic bacteria. By precisely controlling the dissolved oxygen concentration of the solution in the biofilm reactor, the relative ratio (spatial distribution and thickness) of the anoxic and anaerobic zones within the biofilm carrier can be indirectly regulated.

[0020] Further, in step S3, a lower level refers to maintaining the dissolved oxygen content in the solution within the biofilm reactor at 0.2~0.8 mg / L.

[0021] Furthermore, in step S4, the dissolved oxygen concentration of the biofilm reactor solution is controlled to be in the range of 0.2~0.8 mg / L.

[0022] Furthermore, in step S4, when enhancing methanogenesis, the aeration intensity is reduced by adjusting the gas flow meter, and the dissolved oxygen concentration is maintained at 0.2~0.4 mg / L. At this time, the oxygen penetration depth is shallow, and the proportion of anaerobic zone inside the biofilm carrier increases, which is beneficial to the activity of methanogenic bacteria. When enhancing denitrification, the aeration intensity is increased by adjusting the gas flow meter, and the dissolved oxygen concentration is maintained at 0.5~0.8 mg / L. At this time, the oxygen penetration depth into the biofilm carrier increases, the thickness of the anoxic zone expands, providing a wider growth space for denitrifying bacteria, enhancing nitrogen removal efficiency, thereby dynamically optimizing the spatial distribution of the two ecological niches and achieving synergistic effect.

[0023] Furthermore, in step S4, the electric stirrer continues to run to maintain the fluidized state of the biofilm carrier, ensuring that the dissolved oxygen concentration and substrate are evenly distributed within the biofilm reactor, which is conducive to stable gradient formation and mass transfer processes.

[0024] Furthermore, in step S4, in order to achieve precise and dynamic management of the anoxic / anaerobic ratio inside the biofilm carrier, precision instruments such as microelectrodes (Unisense) are used to monitor the dissolved oxygen concentration and redox potential (ORP) profile of the biofilm carrier from the surface to different depths inside in real time. Based on the dissolved oxygen gradient measured by the microelectrodes, the boundary and thickness of the anoxic and anaerobic zones can be accurately defined; at the same time, the ORP profile can provide auxiliary verification.

[0025] The beneficial effects of this invention are as follows:

[0026] (1) This invention utilizes the ecological niche differences in the microspace inside the biofilm carrier to integrate anaerobic digestion and anoxic denitrification processes in a single biofilm reactor, eliminating the need to build a separate denitrification tank. It has the advantages of low energy consumption, small footprint, and strong shock resistance. It can both remove nitrogen and withstand high organic loads, making it suitable for various types of high-concentration organic wastewater.

[0027] (2) The multi-layered spatial structure of the biofilm carrier in the biofilm reactor constructed in this invention makes the functional microorganisms within the biofilm carrier exhibit a clear stratification tendency. By precisely controlling the aeration intensity to regulate the oxygen mass transfer process, and thereby actively regulating the oxygen concentration gradient within the biofilm carrier and its corresponding anoxic / anaerobic region ratio, the growth of denitrifying bacteria and methanogenic bacteria at different depths of the carrier can be controlled, thus effectively overcoming the problem of significant differences in their requirements for DO and ORP.

[0028] (3) In the simultaneous methanogenic denitrification system constructed in this invention, intermediate products of the anaerobic digestion process, such as propionic acid and butyric acid, are preferentially degraded under the action of denitrifying bacteria, thereby improving the efficiency of hydrolysis and acid production. At the same time, the denitrification process can be supplemented by a variety of carbon sources, thus avoiding the complex problems of needing to supplement carbon sources and alkalinity in traditional denitrification processes.

[0029] (4) This invention achieves precise and dynamic management of the anoxic / anaerobic ratio inside the biofilm carrier through microelectrode monitoring and linkage control of process parameters, and realizes stable and efficient synergistic operation of anaerobic digestion and denitrification in the same reactor.

[0030] It is evident that this invention develops a novel treatment technology capable of simultaneously achieving efficient degradation of organic matter and deep removal of nitrogen within a single reactor. By integrating anaerobic nitrification and anoxic denitrification processes in a biofilm reactor, a simultaneous methanogenic denitrification system is constructed. This not only helps optimize the flow and utilization efficiency of carbon sources during pollutant removal but also significantly reduces facility construction and operating costs. It has significant theoretical innovation value and broad engineering application prospects for promoting the transformation of wastewater treatment technology towards a green, low-carbon, and sustainable direction. Attached Figure Description

[0031] The present invention will be described in detail below with reference to the accompanying drawings and examples. The advantages and implementation methods of the present invention will become more apparent from this description. The accompanying drawings are for illustrative purposes only and do not constitute any limitation on the present invention. In the accompanying drawings:

[0032] Figure 1 This is a schematic diagram of the structure of the present invention.

[0033] Figure 2 This is a schematic diagram of the layered structure of the biomembrane carrier of the present invention.

[0034] Figure 3 This is a graph showing the changes in COD concentration and removal rate of the influent and effluent over time according to the present invention.

[0035] Figure 4 This invention relates to NO3 in the influent and effluent water. - -N concentration and removal rate over time.

[0036] In the picture:

[0037] 1. Water distribution tank; 2. Peristaltic pump; 3. Inlet; 4. Biofilm carrier; 5. Biofilm reactor; 6. Electric stirrer; 7. Outlet; 8. Collection tank; 9. Aeration disc; 10. Gas flow meter; 11. Aeration pump. Detailed Implementation

[0038] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the preferred embodiments.

[0039] like Figure 1 As shown, a device for regulating the ecological niche of a biofilm to achieve simultaneous methane production and denitrification includes a biofilm reactor 5, which is cylindrical or rectangular. The biofilm reactor 5 has an inlet 3 on its side wall and an outlet 7 on its top. The outlet 7 is connected to a collection tank 8 and the outlet 7 is an overflow outlet. The inlet 3 is connected to a water distribution tank 1 (which stores wastewater to be treated) via a peristaltic pump 2 for continuous or intermittent water intake. The hydraulic retention time is 6~48h, for example, 6h, 12h, 18h, 36h, 48h, etc.

[0040] The biofilm reactor 5 is equipped with several biofilm carriers 4. These biofilm carriers 4 are polyurethane sponge cubes or suspended packing materials with a certain three-dimensional spatial structure and sufficient porosity, ensuring the formation of anoxic and anaerobic biofilm stratification from the outside to the inside of the biofilm carriers 4 during operation. The biofilm carriers 4 occupy 20% to 50% of the effective volume of the biofilm reactor 5. Of course, the filling rate of the biofilm carriers 4 can be adjusted according to the water volume and water quality.

[0041] The biofilm carrier 4 can be a polyurethane sponge. The biofilm carrier 4 is a cube with a side length of 1-2 cm, such as 1 cm, 1.5 cm, or 2 cm. The density of the biofilm carrier 4 is 20-40 kg / m³. 3 For example, 20kg / m 3 25kg / m 3 30kg / m 335kg / m 3 40kg / m 3 And so on. Moreover, the pore size of the biofilm carrier 4 is 30~60 PPI, such as 30 PPI, 40 PPI, 50 PPI, 60 PPI, etc.

[0042] The biofilm carrier 4 comprises an inner layer, a middle layer, and an outer layer. The inner layer is an anaerobic zone, the middle layer is an anoxic zone, and the outer layer is a diffusion layer. Methanogenic bacteria reside in the anaerobic zone, and denitrifying bacteria reside in the anoxic zone. By controlling the dissolved oxygen concentration of the solution within the biofilm reactor 5, and utilizing the limited diffusion of oxygen within the biofilm carrier 4, a dissolved oxygen gradient is formed from the surface inwards. The middle layer has relatively high dissolved oxygen, forming an anoxic zone dominated by denitrifying bacteria; while the innermost layer of the biofilm carrier 4 forms a strictly anaerobic zone dominated by methanogenic bacteria due to the difficulty of oxygen diffusion. By controlling this gradient, the relative ratio of the anoxic and anaerobic zones within the biofilm carrier 4 can be precisely controlled.

[0043] An aeration disc 9 is installed at the bottom of the biofilm reactor 5. The aeration disc 9 is connected to an external aeration pump 11 and a gas flow meter 10 through a pipeline. The aeration disc 9 uses a microporous aeration head to provide oxygen to the biofilm reactor 5 so that the dissolved oxygen content is within a preset range, thereby ensuring the generation of fine bubbles and uniform oxygen supply. The gas flow meter 10 is used to control the flow rate of gas entering the aeration disc 9 to ensure the formation of an anaerobic-anoxic stratified environment on the biofilm carrier 4.

[0044] An electric stirrer 6 is installed on the top of the biofilm reactor 5. The stirring paddle of the electric stirrer 6 extends into the biofilm reactor 5 for slow stirring, so that the biofilm carrier 4 is in a suspended flow state, ensuring uniform mass transfer and preventing the biofilm carrier 4 from accumulating, while avoiding excessive shear force that could damage the biofilm carrier 4.

[0045] A method for regulating biofilm niches to achieve simultaneous methanogenic denitrification includes the following steps:

[0046] S1. Inoculate the biofilm reactor 5 with mixed sludge taken from the anaerobic digester and denitrification tank, or acclimated sludge containing methanogenic bacteria and denitrifying bacteria.

[0047] S2. Start peristaltic pump 2 to pump the high-concentration organic wastewater (such as kitchen wastewater, NH4 in the influent) after nitrification. + -N is converted to NO3 by nitration. - -N, COD concentration range is approximately 5000~30000 mg / L, NO3 -The raw water (containing organic matter and nitrates) with a nitrogen concentration ranging from approximately 200 to 1000 mg / L is continuously fed into the biofilm reactor 5 to acclimate the biofilm carrier 4. The high-concentration organic wastewater can also be aquaculture wastewater, brewery wastewater, food wastewater, etc.

[0048] S3. In the initial stage of acclimatization, the aeration rate is controlled at a very low level by using the aeration pump 11 and the gas flow meter 10 to maintain the dissolved oxygen (DO) in the biofilm reactor 5 at a low level (e.g., 0.2~0.8 mg / L). The acclimatization process continues for several weeks until a biofilm is formed on the surface and internal pores of the biofilm carrier 4, and the removal efficiency of COD and nitrate tends to stabilize.

[0049] S4, Formation and Regulation of the Four-Layer Structure of Biomembrane Carriers:

[0050] like Figure 2 As shown, the aeration intensity (oxygen supply) is controlled by the gas flow meter 10. Utilizing the diffusion limitation of oxygen within the biofilm carrier 4, the penetration depth of oxygen into the biofilm carrier 4 is controlled, naturally forming a dissolved oxygen gradient from the surface inwards. The middle layer of the biofilm carrier 4 has a relatively high DO concentration, forming an anoxic zone dominated by denitrifying bacteria; the inner layer of the biofilm carrier 4 has extremely low DO concentration, even zero, forming a strictly anaerobic zone dominated by methanogenic bacteria. By precisely controlling the DO concentration of the solution in the biofilm reactor 5 (a preset range, e.g., 0.2~0.8 mg / L), the relative ratio (spatial distribution and thickness) of the anoxic and anaerobic zones within the biofilm carrier 4 is indirectly regulated.

[0051] To enhance methanogenesis (for high organic loads), the aeration intensity is reduced using gas flow meter 10 to maintain a low DO level (e.g., 0.2-0.4 mg / L). At this level, oxygen penetration is shallow, increasing the proportion of anaerobic zones within the biofilm carrier 4, which is beneficial for methanogenic bacteria activity. Conversely, to enhance denitrification (when influent nitrogen load is high), the aeration intensity is appropriately increased using gas flow meter 10 (while still maintaining a low-oxygen environment, e.g., 0.5-0.8 mg / L). This increases oxygen penetration into the biofilm carrier 4, expanding the anoxic zone and providing a wider growth space for denitrifying bacteria, thus enhancing nitrogen removal efficiency. This dynamically optimizes the spatial distribution of the two niches, achieving synergistic effects.

[0052] In step S4, the electric stirrer 6 continues to run, keeping the biofilm carrier 4 in a fluidized state, ensuring that DO and substrate are evenly distributed in the biofilm reactor 5, which is conducive to stable gradient formation and mass transfer process.

[0053] In step S4, in order to achieve precise and dynamic management of the anoxic / anaerobic ratio inside the biofilm carrier 4, precision instruments such as microelectrodes (Unisense) are used to monitor the dissolved oxygen (DO) and redox potential (ORP) profiles of the biofilm carrier 4 from the surface to different depths inside in real time.

[0054] Based on the DO gradient measured by the microelectrode (e.g., the DO concentration gradually decreases from >0.1 mg / L on the surface of biofilm carrier 4 with increasing depth, and drops to <0.01 mg / L at a certain depth), the boundary and thickness of the anoxic and anaerobic zones can be accurately defined.

[0055] Meanwhile, ORP profiles (e.g., from negative tens of mV in the anoxic zone to below -200 mV in the internal anaerobic zone) can provide auxiliary verification.

[0056] Based on the above real-time monitoring data, feedback adjustment is performed (reverse fine adjustment of the oxygen supply and / or stirring conditions of aeration pump 11 and gas flow meter 10): if the monitoring finds that the thickness of the internal anaerobic zone is insufficient, affecting the methanogenic effect, the setting of gas flow meter 10 is lowered in reverse to reduce the oxygen supply; if the monitoring finds that the thickness of the anoxic zone is insufficient and denitrification is incomplete, the oxygen supply is appropriately increased through gas flow meter 10.

[0057] Through this coordinated regulation, the target anoxic / anaerobic ratio can be dynamically optimized and maintained, ensuring that denitrifying bacteria and methanogenic bacteria metabolize efficiently in their respective optimal ecological niches. This achieves the best operational efficiency of biofilm reactor 5 for organic matter degradation and denitrification. Typical effects can be found in [reference needed]. Figure 3 COD removal rate and Figure 4 NO3 - -N removal rate.

[0058] like Figure 3As shown, continuous operation monitoring of the influent and effluent of biofilm reactor 5 was conducted for 35 days, with COD concentration and removal rate as the core indicators for performance evaluation. The influent COD concentration remained generally within the medium-high load range of 6000-8000 mg / L, initially stable at 6000-7000 mg / L, and then showing a slow upward trend, indicating relatively small fluctuations in raw water quality and a relatively stable load. The effluent COD concentration continuously decreased from approximately 2000 mg / L initially, stabilizing below 1000 mg / L in the later stages of operation, reflecting the gradual improvement in the treatment capacity of biofilm reactor 5 over time and continuous optimization of effluent quality. The COD removal rate gradually increased from approximately 70% initially, stabilizing above 90% in the later stages, reaching a peak close to 100%, indicating continuous optimization of the operating performance of biofilm reactor 5, ultimately achieving efficient and stable COD removal. In summary, under medium-high COD influent conditions, the treatment performance of biofilm reactor 5 can be improved through regulation, ultimately achieving stable and excellent COD removal results, demonstrating good operational stability and treatment efficiency.

[0059] like Figure 4 As shown, continuous monitoring of the influent and effluent of biofilm reactor 5 was conducted for 35 days, with nitrate nitrogen (NO3) as the primary nitrogen content. - -N) concentration and removal rate are the core indicators for evaluating the nitrogen removal performance of the system. Influent NO3 - -N concentration remained generally within the medium-to-high load range of 250-400 mg / L, initially stabilizing at 300-350 mg / L, and then showing a slow upward trend, indicating that the raw water quality fluctuated relatively little and the load was within a controllable range. (Effluent NO3) - The NO3- concentration decreased continuously from an initial level of approximately 150-200 mg / L, stabilizing below 50 mg / L in the later stages of operation. This reflects that the biofilm reactor 5's capacity to treat nitrate nitrogen gradually increased with operating time, resulting in continuous optimization of effluent quality. - The nitrogen removal rate gradually increased from approximately 30% initially, stabilizing in the 35%–40% range later, indicating that the performance of biofilm reactor 5 was continuously optimized, ultimately achieving a stable nitrate nitrogen removal effect. In summary, under medium-to-high concentration nitrate nitrogen influent conditions, biofilm reactor 5 can improve its nitrogen removal performance through regulation, ultimately achieving a stable nitrate nitrogen removal effect, demonstrating good operational stability and nitrogen removal efficiency.

[0060] In summary, through the above design scheme, the small-molecule organic acids (such as propionic acid and butyric acid) produced during anaerobic digestion can be preferentially utilized as high-quality carbon sources for denitrifying bacteria in the constructed and optimized simultaneous methanogenic denitrification system. This not only promotes the denitrification process but also alleviates the potential inhibition of methanogenic bacteria by organic acid accumulation, thereby improving overall stability and treatment efficiency. The denitrification process consumes hydrogen ions, which helps maintain the alkalinity balance within biofilm reactor 5, creating a more suitable environment for pH-sensitive methanogenic bacteria. Therefore, organic matter removal (methanogenesis) and nitrogen removal (denitrification) are completed within a single reactor, simplifying the process and reducing energy consumption and floor space requirements.

[0061] Through the above specific implementation methods, the efficient synergistic operation of anaerobic digestion and denitrification can be effectively achieved in a single biofilm reactor 5, thereby improving the efficiency of organic matter degradation and nitrogen removal in high-concentration organic wastewater.

[0062] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A device for regulating biofilm ecological niches to achieve simultaneous methane production and denitrification, characterized in that: The device includes a biofilm reactor with an inlet on its side wall and an outlet at its top. The inlet is connected to a distribution tank via a peristaltic pump, which stores wastewater to be treated. The biofilm reactor contains several biofilm carriers that, during operation, form a layered structure of anoxic and anaerobic biofilms from the outside in. An aeration disc is installed at the bottom of the biofilm reactor, and the disc is connected to an external aeration pump and a gas flow meter via pipelines.

2. The device for regulating biofilm ecological niches to achieve simultaneous methane production and denitrification according to claim 1, characterized in that: The biofilm carrier occupies 20% to 50% of the effective volume of the biofilm reactor.

3. The device for regulating biofilm ecological niches to achieve simultaneous methane production and denitrification according to claim 1, characterized in that: The biofilm carrier is a polyurethane sponge cube or a suspended packing material.

4. The device for regulating biofilm ecological niches to achieve simultaneous methane production and denitrification according to claim 1, characterized in that: The biofilm carrier is a cube with a side length of 1-2 cm; the density of the biofilm carrier is 20-40 kg / m³. 3 Furthermore, the pore size of the biofilm carrier is 30~60 PPI.

5. The device for regulating biofilm ecological niches to achieve simultaneous methane production and denitrification according to claim 1, characterized in that: The biofilm carrier comprises an inner layer, a middle layer, and an outer layer. The inner layer is an anaerobic zone, the middle layer is an anoxic zone, and the outer layer is a diffusion layer. Methanogenic bacteria reside in the anaerobic zone, and denitrifying bacteria reside in the anoxic zone.

6. The device for regulating biofilm ecological niches to achieve simultaneous methane production and denitrification according to claim 1, characterized in that: An electric stirrer is installed on the top of the biofilm reactor, and the stirring paddle of the electric stirrer extends into the biofilm reactor.

7. A method for simultaneously producing methane and denitrifying by regulating the ecological niche of a biofilm, comprising the apparatus for simultaneously producing methane and denitrifying by regulating the ecological niche of a biofilm as described in any one of claims 1 to 6, characterized in that: Includes the following steps: S1. Inoculate the biofilm reactor with mixed sludge taken from the anaerobic digester and denitrification tank, or acclimated sludge containing methanogenic bacteria and denitrifying bacteria. S2. Start the peristaltic pump and continuously feed the high-concentration organic wastewater after nitrification into the biofilm reactor as raw water for acclimatization to acclimatize the biofilm carrier. S3. In the early stage of acclimatization, the aeration rate is controlled by the aeration pump and gas flow meter to maintain the dissolved oxygen in the biofilm reactor at a low level until a biofilm is formed on the surface and internal pores of the biofilm carrier. S4. Formation and Regulation of Layered Structure of Biofilm Carrier: The aeration intensity is controlled by a gas flow meter. By utilizing the diffusion limitation of oxygen within the biofilm carrier, the penetration depth of oxygen into the interior of the biofilm carrier is controlled, forming a dissolved oxygen gradient from the surface to the interior. The middle layer of the biofilm carrier has a relatively high dissolved oxygen concentration, forming an anoxic zone dominated by denitrifying bacteria. The inner layer of the biofilm carrier has an extremely low or even zero dissolved oxygen concentration, forming a strictly anaerobic zone dominated by methanogenic bacteria. The ratio of anoxic to anaerobic zones within the biofilm carrier is regulated by controlling the dissolved oxygen concentration of the solution in the biofilm reactor.

8. The method for simultaneously producing methane and denitrifying by regulating the ecological niche of a biofilm according to claim 7, characterized in that: In step S3, a lower level refers to maintaining the dissolved oxygen content in the solution within the biofilm reactor at 0.2~0.8 mg / L.

9. The method for regulating biofilm ecological niches to achieve simultaneous methanogenic denitrification according to claim 7, characterized in that: In step S4, the dissolved oxygen concentration of the biofilm reactor solution is controlled within the range of 0.2~0.8 mg / L; when enhancing methanogenesis, the aeration intensity is reduced by using a gas flow meter, and the dissolved oxygen concentration is maintained at 0.2~0.4 mg / L; when enhancing denitrification, the aeration intensity is increased by using a gas flow meter, and the dissolved oxygen concentration is maintained at 0.5~0.8 mg / L.

10. The method for simultaneously producing methane and denitrifying by regulating the ecological niche of a biofilm according to claim 7, characterized in that: In step S4, microelectrodes are used to monitor the dissolved oxygen concentration and redox potential profile of the biofilm carrier at different depths from the surface to the interior in real time.

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