Carrousel oxidation ditch denitrification operation method

Abstract

The invention provides a Carrousel oxidation ditch denitrification operation method which comprises the following steps: step S10, mounting positions are preset on the pool wall of a tail end area of an oxidation ditch, two efficient submersible internal reflux pumps are fixed, and the internal reflux pumps are provided with frequency conversion control systems; s20, a traditional surface inverted umbrella aerator is dismantled, distributed aeration discs are installed at the bottom of the oxidation ditch pool according to the matrix type layout, and a magnetic suspension centrifugal blower is arranged in a matched mode to serve as an aeration air source; and step S30, transforming the internal structure of the oxidation ditch pool body, adjusting the space ratio of the anoxic zone to the aerobic zone from the original 2: 3 to 1: 1, prolonging the retention time tA of the anoxic zone to 8.6 h, and synchronously adjusting the retention time tO of the aerobic zone to 8.6 h so as to meet the dynamic requirements of denitrification reaction. According to the technical scheme, the problems that in the prior art, backflow in the Carrousel oxidation ditch cannot be accurately metered, and the fixed proportion of the anoxic section and the aerobic section does not meet the dynamic requirement of the denitrification reaction can be effectively solved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method for denitrification operation in a Carrousel oxidation ditch. Background Technology

[0002] In the current wastewater treatment field, the Carrousel oxidation ditch 2000 tank type is widely used for denitrification treatment of municipal wastewater. Its core process relies on a series structure of an anoxic section at the front end and an aerobic section at the rear end. Internal recirculation of nitrified liquid is achieved through traditional weir plate regulation, and mechanical surface aerators are used for aeration and oxygen supply. In this process, the volume ratio of the anoxic to aerobic section is typically 2:3, with a residence time of approximately 6 hours in the anoxic section and approximately 9 hours in the aerobic section. Internal recirculation relies on natural overflow from the weir plates, lacking flow metering and control capabilities. The aeration system operates on a fixed basis and cannot be dynamically adjusted according to the dissolved oxygen (DO) concentration in the tank, resulting in low oxygen transfer efficiency. The DO concentration in the aerobic section is often higher than 2.0 mg / L, leading to high energy consumption and limited denitrification efficiency. The total nitrogen (TN) removal rate is generally below 70%, and it is difficult to consistently achieve effluent TN below 10 mg / L.

[0003] In the aforementioned technologies, the internal recirculation relies on the weir plate structure, making it impossible to accurately measure and dynamically adjust the recirculation flow rate. This leads to unstable nitrification liquor recirculation and insufficient nitrate nitrogen supply required for denitrification. The fixed ratio of the anoxic to aerobic zone at 2:3 fails to match the kinetic requirements of denitrification, resulting in insufficient denitrification residence time and limiting total nitrogen removal efficiency. Surface aerators cannot achieve precise oxygen supply in different zones, generally exhibiting over-aeration, high power consumption, and low oxygen utilization. Furthermore, the rigid design of the tank's functional zones lacks the flexibility to cope with fluctuations in influent water quality and quantity. When the influent TN or COD concentration suddenly increases, the system's shock resistance is weak, resulting in large fluctuations in effluent water quality and difficulty in meeting increasingly stringent environmental emission standards. Summary of the Invention

[0004] This application provides a method for denitrification operation in a Carrousel oxidation ditch, including: Step S10: Remove the original weir plate adjustment structure, and fix two high-efficiency submersible internal return pumps at preset installation positions on the pool wall at the end of the oxidation ditch. The internal return pumps are equipped with a variable frequency control system; adjust the operating frequency f of the internal return pumps through the variable frequency drive, combined with the rated flow rate Q of the internal return pumps. n According to the formula Qr=Q n×(f / 50) Real-time calculation and dynamic control of internal return flow Qr to achieve accurate metering of internal return flow and uniform hydraulic flow; Step S20: Remove the traditional surface umbrella aerator and install distributed aeration discs in a matrix layout at the bottom of the oxidation ditch, and deploy magnetic levitation centrifugal blowers as aeration air source; Based on the real-time feedback of dissolved oxygen concentration DO in the aerobic section, dynamically adjust the air pressure and air volume of the magnetic levitation centrifugal blowers to control the DO in the aerobic section within the range of 0.7–1.5 mg / L; Step S30: Modify the internal structure of the oxidation ditch, adjust the space ratio of the anoxic section to the aerobic section from the original 2:3 to 1:1, extend the residence time tA in the anoxic section to 8.6 h, and simultaneously adjust the residence time tO in the aerobic section to 8.6 h to match the kinetic requirements of denitrification reaction.

[0005] Furthermore, after step S30, a variable function area is added at the rear end of the oxidation ditch. This area is equipped with an independent aeration control panel and a flow guiding device. The concentration data of COD, ammonia nitrogen, and total nitrogen in different areas of the tank are monitored by online instruments. When the influent TN0 is higher than the design value, the aeration system of the variable function area is closed by the aeration valve on the aeration control panel, making this area a post-anoxic section. When the influent COD concentration is too high, the aeration system of the variable function area is opened by the aeration valve on the aeration control panel, making this area an aerobic extension section. Data acquisition is the premise of decision-making, and the decision result drives the action of the aeration control panel. The three form a closed-loop control chain. Among them, the online instruments are DO, nitrate nitrogen, and ORP instruments. Data acquisition can be carried out by combining instantaneous manual sampling with feedback empirical values ​​from online instruments.

[0006] Furthermore, the total nitrogen removal rate η = (TN0 - TN1) / TN0 × 100%, and the total nitrogen concentration in the effluent is stably controlled below 10 mg / L. This value is calculated from the effluent water quality result TN1 after the coordinated operation of steps S10, S20, and S30 and the total nitrogen concentration in the influent TN0.

[0007] Furthermore, the magnetic levitation centrifugal blower adopts contactless bearing technology and is equipped with distributed aeration discs to improve oxygen transfer efficiency. This technical feature is the structural feature of the magnetic levitation centrifugal blower and distributed aeration discs in step S20.

[0008] Furthermore, the renovation plan does not require large-scale reconstruction of the pool, has a short construction period and low renovation cost, and can be widely applied to the upgrading and renovation of existing Carrousel oxidation ditch 2000 pool types.

[0009] Furthermore, the amount of carbon source reagent added is reduced, resulting in lower operating costs. This is due to the improved sufficiency of the denitrification reaction in step S30.

[0010] Applying the technical solution of this application, the Carrousel oxidation system removes the original weir plate adjustment structure and fixes two high-efficiency submersible internal return pumps at preset installation positions on the end pool wall, and configures a variable frequency control system to achieve precise dynamic control of the internal return flow: by real-time monitoring of the internal return pump operating frequency f, combined with its rated flow rate Q... n According to the formula Qr=Q n ×(f / 50) calculates the actual return flow rate, ensuring a precise match between the internal return rate and process requirements. This completely eliminates the shortcomings of traditional weir plate regulation, which relies on manual experience, suffers from large flow fluctuations, and is impossible to measure, significantly improving the stability and repeatability of the internal return process. Simultaneously, inefficient traditional surface umbrella aerators are removed, and distributed aeration discs are installed in a matrix layout at the bottom of the tank, equipped with magnetic levitation centrifugal blowers as the air source. Based on real-time feedback of dissolved oxygen (DO) concentration in the aerobic section, the blower's pressure and airflow are dynamically adjusted to precisely maintain DO between 0.7 and 1.5. The high-efficiency nitrogen removal window of mg / L avoids energy waste and nitrate accumulation caused by uneven or excessive aeration. Furthermore, by reconstructing the internal structure of the oxidation ditch, the spatial ratio of the anoxic and aerobic sections was optimized from 2:3 to 1:1, extending the residence time of both sections to 8.6 hours. This fundamentally matches the reaction kinetics requirements of denitrifying bacteria for carbon source utilization and nitrate reduction, solving the technical bottleneck of low nitrogen removal efficiency and excessive total nitrogen in effluent due to insufficient residence time in the anoxic section. The synergistic effect of these three elements achieves a three-in-one optimization of precise internal reflux metering, intelligent aeration control, and reaction phase timing matching, significantly improving nitrogen removal efficiency and operational stability. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the oxidation ditch tank structure of the present invention.

[0012] In the diagram, 1 is the anoxic zone; 2 is the aerobic zone; 3 is the variable function zone; 4 is the internal reflux pump; and 5 is the aeration disc. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0014] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0015] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0016] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0017] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0018] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] This application provides a method for denitrification operation in a Carrousel oxidation ditch, including: Step S10: removing the original weir plate adjustment structure, fixing two high-efficiency submersible internal return pumps at preset installation positions on the pool wall at the end of the oxidation ditch, the internal return pumps being equipped with a variable frequency control system; adjusting the operating frequency fHz of the internal return pumps through the variable frequency drive, combined with the rated flow rate Q of the internal return pumps. n According to the formula Qr=Q n×(f / 50) Real-time calculation and dynamic control of internal return flow Qr to achieve accurate metering of internal return flow and uniform hydraulic flow; Step S20: Remove the traditional surface umbrella aerator and install distributed aeration discs in a matrix layout at the bottom of the oxidation ditch, and deploy magnetic levitation centrifugal blowers as aeration air source; Based on the real-time feedback of dissolved oxygen concentration DO in the aerobic section, dynamically adjust the air pressure and air volume of the magnetic levitation centrifugal blowers to control the DO in the aerobic section within the range of 0.7–1.5 mg / L; Step S30: Modify the internal structure of the oxidation ditch, adjust the space ratio of the anoxic section to the aerobic section from the original 2:3 to 1:1, extend the residence time tA in the anoxic section to 8.6h, and simultaneously adjust the residence time tO in the aerobic section to 8.6h to match the kinetic requirements of denitrification reaction.

[0020] Applying the technical solution of this embodiment, two high-efficiency submersible internal return pumps are fixed at preset installation positions on the pool wall at the end of the Carrousel oxidation ditch. The internal return pumps are equipped with a variable frequency control system. The operating frequency f Hz of the internal return pumps is adjusted by the frequency converter, combined with the rated flow rate Q of the internal return pumps. n According to the formula Qr=Q n ×(f / 50) Real-time calculation and dynamic control of the internal recirculation flow rate Qr achieves precise metering of internal recirculation and uniform hydraulic flow, thus completely eliminating the defect of traditional weir plate regulation structures that cannot accurately measure internal recirculation and solving the technical problem of inaccurate internal recirculation measurement. Simultaneously, the traditional surface umbrella aerators are removed, and distributed aeration discs are installed in a matrix layout at the bottom of the oxidation ditch, equipped with magnetic levitation centrifugal blowers as the aeration air source. Based on real-time feedback of the dissolved oxygen concentration (DO) in the aerobic section, the air pressure and air volume of the magnetic levitation centrifugal blowers are dynamically adjusted to stably control the DO in the aerobic section within the range of 0.7–1.5 mg / L, ensuring efficient nitrification and avoiding energy waste. Furthermore, the internal structure of the oxidation ditch is modified, adjusting the space ratio of the anoxic and aerobic sections from the original 2:3 to 1:1, extending the residence time tA in the anoxic section to 8.6 h, and simultaneously adjusting the residence time tO in the aerobic section to 8.6 h. h, thereby precisely matching the residence time requirements of the anoxic environment for the denitrification reaction kinetics, significantly improving nitrogen removal efficiency, and fundamentally solving the technical problem of the mismatch between the fixed ratio of the anoxic and aerobic sections and the requirements of the denitrification reaction kinetics.

[0021] Furthermore, in this embodiment, after step S30, a variable function area is added at the rear end of the oxidation ditch. This area is equipped with an independent aeration control panel and a flow guiding device. The COD, ammonia nitrogen, and total nitrogen concentration data of different areas in the tank are monitored by online instruments. When the influent TN0 is higher than the design value, the aeration system of the variable function area is shut down, and the area is switched to the post-anoxic section. When the influent COD concentration is too high, the aeration system of the variable function area is turned on, and the area is used as the aerobic extension section. Data acquisition is the premise for decision-making, and the decision result drives the aeration control panel to act. The three constitute a closed-loop control chain.

[0022] In this embodiment, when a variable functional area is added to the rear end of the oxidation ditch and an independent aeration control panel and flow guiding device are configured, the COD, ammonia nitrogen, and total nitrogen concentration data of different areas in the tank are monitored in real time by online instruments. The system can make dynamic decisions based on whether the influent TN0 is higher than the design value: if the monitored value exceeds the limit, the aeration control panel is triggered to shut down the aeration system in that area, and the flow guiding device guides the water flow to form a post-anoxic section, extending the denitrification reaction time to enhance the denitrification capacity; if the influent COD concentration is detected to be too high, the aeration control panel is driven to turn on the aeration system, converting the area into an aerobic extension section, enhancing the organic matter degradation efficiency. Data acquisition, intelligent decision-making, and aeration control panel actions form a closed-loop control chain, enabling the oxidation ditch functional zones to automatically adapt to water quality fluctuations, breaking through the original 1:1 fixed zoning's adaptability bottleneck to changes in influent, and significantly improving the stability and operational resilience of the effluent water quality.

[0023] Furthermore, in this embodiment, the total nitrogen removal rate η = (TN0 - TN1) / TN0 × 100%, and the total nitrogen concentration in the effluent is stably controlled below 10 mg / L. This value is calculated from the effluent water quality result TN1 after the coordinated operation of steps S10, S20, and S30 and the total nitrogen concentration in the influent TN0.

[0024] In this embodiment, by removing the original weir plate adjustment structure and fixing two high-efficiency submersible internal return pumps at preset installation positions on the pool wall at the end of the oxidation ditch, and in conjunction with their configured variable frequency control system, based on the operating frequency f and the rated flow rate Q... n According to the formula Qr=Q n×(f / 50) Real-time calculation and dynamic control of the internal recirculation flow rate Qr achieves precise metering and uniform hydraulic flow. Simultaneously, traditional surface umbrella aerators are removed, and distributed aeration discs are installed in a matrix layout at the bottom of the oxidation ditch, equipped with magnetic levitation centrifugal blowers as the aeration air source. The air pressure and air volume of the magnetic levitation centrifugal blowers are dynamically adjusted based on real-time feedback of the dissolved oxygen concentration (DO) in the aerobic section, ensuring stable DO control within the range of 0.7 to 1.5 mg / L. Furthermore, the internal structure of the oxidation ditch is modified, adjusting the space ratio between the anoxic and aerobic sections from the original 2:3 to 1:1, thus improving the anoxic... The retention time tA in the first stage and the retention time tO in the aerobic stage were both extended to 8.6 hours to match the kinetic requirements of the denitrification reaction. Based on this, the total nitrogen removal rate was calculated by real-time monitoring of the total nitrogen concentration TN0 in the influent and the total nitrogen concentration TN1 in the effluent, according to the formula η=(TN0-TN1) / TN0×100%. The operating target was to stably control the total nitrogen concentration in the effluent below 10mg / L. This ensured that the internal return pump, distributed aeration discs, magnetic levitation centrifugal blower, and the modified anoxic and aerobic stages worked synergistically to form a closed-loop quantitative control system, ensuring that the nitrogen removal effect was measurable, controllable, and stably met the standards.

[0025] Furthermore, in this embodiment, the magnetic levitation centrifugal blower adopts contactless bearing technology, and the distributed aeration discs are deployed in conjunction to improve oxygen transfer efficiency. This technical feature is the structural feature of the magnetic levitation centrifugal blower and the distributed aeration discs in step S20.

[0026] In this embodiment, the magnetic levitation centrifugal blower adopts contactless bearing technology, which eliminates the friction loss caused by traditional mechanical bearings, enabling the blower to maintain efficient and stable airflow output during long-term operation. Combined with distributed aeration discs, it achieves precise and uniform oxygen release, effectively avoiding air pressure fluctuations and increased energy consumption caused by mechanical wear. This technological feature, along with the synergistic effect of the magnetic levitation centrifugal blower as an aeration source and the distributed aeration discs, significantly improves the operational stability and service life of the aeration system while dynamically adjusting air pressure and volume to maintain the dissolved oxygen concentration in the aerobic section within the range of 0.7–1.5 mg / L. Simultaneously, it reduces maintenance frequency and operating costs, providing a reliable air source guarantee for precise control of reflux in the Carrousel oxidation ditch and optimization of denitrification kinetics under a 1:1 spatial ratio between the anoxic and aerobic sections.

[0027] Furthermore, in this embodiment, the modification scheme does not require large-scale reconstruction of the pool body, has a short construction period and low modification cost, and can be widely applied to the upgrading and modification of existing Carrousel oxidation ditch 2000 pool types.

[0028] In this embodiment, by removing the original weir plate adjustment structure and fixing two high-efficiency submersible internal return pumps at pre-installed positions on the pool wall at the end of the oxidation ditch, and in conjunction with their configured variable frequency control system, precise dynamic control of the internal return flow rate Qr is achieved. Simultaneously, the traditional surface umbrella aerator is removed, and distributed aeration discs are installed in a matrix layout at the bottom of the oxidation ditch, equipped with magnetic levitation centrifugal blowers as the aeration air source. The air pressure and air volume are adjusted based on real-time feedback of the dissolved oxygen concentration (DO) in the aerobic section, ensuring that DO is stably maintained within the range of 0.7–1.5 mg / L. The modification to the internal structure of the oxidation ditch is limited to adjusting the position of the baffles, optimizing the space ratio between the anoxic and aerobic sections from the original 2:3 to 1:1, thus extending the residence time tA in the anoxic section and the residence time tO in the aerobic section to 8.6. h. This adjustment does not involve the demolition or reconstruction of the pool's basic structure. All equipment installation and partition reconstruction are completed while retaining the original pool walls, bottom plate, and overall outline. Therefore, there is no need for large-scale reconstruction of the pool, which significantly shortens the construction cycle and reduces the transformation cost. This solution can be directly applied to the upgrade and transformation of the existing Carrousel oxidation ditch 2000 pool type, achieving synergistic optimization of denitrification efficiency and engineering economy.

[0029] Furthermore, in this embodiment, the amount of carbon source reagent added is reduced, resulting in lower operating costs. This is due to the improved sufficiency of the denitrification reaction in step S30.

[0030] In this embodiment, by adjusting the spatial ratio of the anoxic and aerobic sections to 1:1, the residence time tA in the anoxic section is extended to 8.6 h, and the residence time tO in the aerobic section is simultaneously adjusted to 8.6 h, significantly improving the sufficiency of the denitrification reaction. Since the residence time in the anoxic environment matches the kinetic requirements of microbial denitrification, nitrate nitrogen is more thoroughly reduced in the anoxic section, thereby reducing the dependence on external carbon source agents, reducing the amount of carbon source agents added, and correspondingly reducing operating costs. This effect is entirely caused by the structural ratio adjustment and does not depend on the addition of new equipment, control logic, or changes in external agent addition strategies. Furthermore, the precise metering of internal recirculation and dynamic control of dissolved oxygen achieved by the high-efficiency submersible internal recirculation pump and distributed aeration discs provide a stable operating foundation for the improvement of denitrification efficiency. However, the direct reason for the saving of carbon source is only due to the reconstruction of the spatial ratio of the anoxic and aerobic sections.

[0031] The technical solution of this application is described below: The original weir plate adjustment structure is removed, and two high-efficiency submersible internal return pumps are fixed at pre-installed positions on the pool wall at the end of the oxidation ditch. The internal return pumps are equipped with a frequency converter control system; the operating frequency f Hz of the internal return pumps is adjusted via the frequency converter, combined with the rated flow rate Q of the internal return pumps. n According to the formula Qr=Q n×(f / 50) Real-time calculation and dynamic control of the internal recirculation flow rate Qr achieves precise metering of internal recirculation and uniform hydraulic flow. Simultaneously, traditional surface umbrella aerators are removed, and distributed aeration discs are installed in a matrix layout at the bottom of the oxidation ditch, with magnetic levitation centrifugal blowers deployed as the aeration air source. Based on real-time feedback of dissolved oxygen concentration (DO) in the aerobic section, the air pressure and air volume of the magnetic levitation centrifugal blowers are dynamically adjusted to stably control the DO in the aerobic section within the range of 0.7–1.5 mg / L. The internal structure of the oxidation ditch is modified, adjusting the space ratio of the anoxic and aerobic sections from the original 2:3 to 1:1, extending the residence time tA in the anoxic section to 8.6 h, and simultaneously adjusting the residence time tO in the aerobic section to 8.6 h. h; A variable function zone is added at the rear end of the oxidation ditch, which is equipped with an independent aeration control panel and a flow guiding device; COD, ammonia nitrogen, and total nitrogen concentration data in different areas of the tank are monitored by online instruments. When the influent TN0 is higher than the design value, the aeration system of the variable function zone is shut down, and the flow guiding device guides the water flow to form a post-anoxic section; when the influent COD concentration is too high, the aeration system of the variable function zone is turned on, so that the zone is converted into an aerobic extension section; based on the influent total nitrogen concentration TN0 and the effluent total nitrogen concentration TN1, the total nitrogen removal rate is calculated according to the formula η=(TN0-TN1) / TN0×100%, and the effluent total nitrogen concentration is stably controlled below 10 mg / L as the operating target. The internal return pump, distributed aeration disc, magnetic levitation centrifugal blower, the modified anoxic and aerobic section structure, and the variable function zone work together to form a closed-loop quantitative control system.

[0032] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for denitrification operation in a Carrousel oxidation ditch, characterized in that, include: Step S10: Fix two high-efficiency submersible internal return pumps at preset installation positions on the pool wall at the end of the oxidation ditch. The internal return pumps are equipped with a variable frequency control system. The operating frequency f (Hz) of the internal reflux pump is adjusted by a frequency converter, combined with the rated flow rate Q of the internal reflux pump. n According to the formula Qr=Q n ×(f / 50) Real-time calculation and dynamic control of internal recirculation flow Qr to achieve accurate internal recirculation measurement and uniform hydraulic flow; Step S20: Remove the traditional surface umbrella aerator and install distributed aeration discs in a matrix layout at the bottom of the oxidation ditch. Attach a magnetic levitation centrifugal blower as the aeration air source. Based on real-time feedback of the dissolved oxygen concentration (DO) in the aerobic section, dynamically adjust the air pressure and air volume of the magnetic levitation centrifugal blower to control the DO in the aerobic section within the range of 0.7–1.5 mg / L. Step S30: Modify the internal structure of the oxidation ditch pool by dividing the internal space of the oxidation ditch into zones through the pool partition, and adjust the space ratio of the anoxic zone and the aerobic zone to be equal so that the hydraulic retention time of the anoxic zone and the aerobic zone are matched.

2. The method for denitrification operation of a Carrousel oxidation ditch according to claim 1, characterized in that: After step S30, a variable function area is added at the rear end of the oxidation ditch. This area is equipped with an independent aeration control panel and flow guiding device. Online instruments monitor the COD, ammonia nitrogen, and total nitrogen concentrations in different areas of the tank. When the influent T... N0 When the COD concentration in the influent exceeds the design value, the aeration system of the variable function zone is shut off by the aeration valve on the aeration control panel, switching that zone to a post-anoxic section. When the COD concentration in the influent is too high, the aeration system of the variable function zone is opened by the aeration valve on the aeration control panel, making that zone an aerobic extension section. Data acquisition is the prerequisite for decision-making, and the decision results drive the action of the aeration control panel. The three constitute a closed-loop control chain.

3. The method for denitrification operation of a Carrousel oxidation ditch according to claim 1, characterized in that: The formula for calculating the total nitrogen removal rate is: η = (T N0 -T N1 ) / T N0 ×100%; Where: -η: Total nitrogen removal rate (%); -T N0 : Total nitrogen concentration in influent (mg / L); -T N1 : Total nitrogen concentration in effluent (mg / L).

4. The method for denitrification operation of a Carrousel oxidation ditch according to claim 1, characterized in that: In step S30, the spatial ratio of the anoxic zone to the aerobic zone is 1:1, and the residence time t in the anoxic zone is... A Extended to 8.6 h, aerobic residence time t O The synchronization time has been adjusted to 8.6 hours.

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