A spiral rotating disc type MABR autotrophic denitrification reactor and operation control method

Abstract

The present application relates to sewage treatment technical field, specifically to a spiral rotating disc type MABR autotrophic denitrification reactor and operation control method, through optimizing setting the number of membrane filaments in different areas of the inner and outer rings of the spiral rotating disc type MABR membrane assembly, the sludge accumulation phenomenon caused by the over-thick biofilm formed on the inner ring MABR membrane filaments is avoided to the maximum extent; through the biofilm strengthening reduction operation, the water level of the membrane reaction tank can be controlled to be reduced, the radial proportion of the membrane assembly exposed to the water surface is regulated, the hydraulic shear force of the gas-liquid interface under the rotating state is enhanced, the effective removal of the biofilm in the inner ring of the membrane assembly is realized, and the uniformity of the over-thick biofilm removal of the MABR membrane element is enhanced; through adjusting and controlling the rotating speed of the spiral rotating disc type MABR membrane assembly, the uniform mixing of the sewage in the reaction device can be realized, and the plug flow effect of the sewage in the axial direction of the membrane assembly can be realized; through the multi-point bottom water inlet, the uniform water distribution and the periodic pulse water inlet mode can be realized, and the uniform agitation of the bottom granular sludge area is completed.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a spiral rotary MABR autotrophic denitrification reactor and its operation control method. Background Technology

[0002] Aerated membrane biofilm reactors (MABRs) are a novel wastewater treatment process that organically integrates traditional biofilm methods with gas separation membrane technology. Oxygen-permeable membranes supply oxygen to the bioreactor, while microorganisms readily attach and grow on the membrane surface to form a biofilm, thereby efficiently degrading pollutants in the water. In recent years, MABR technology, while meeting the requirements of efficient organic matter removal and energy saving, has been more widely applied in the biological denitrification process of wastewater treatment. Its heterogeneous mass transfer characteristics make it easy for microorganisms such as ammonia-oxidizing bacteria and nitrite-oxidizing bacteria to accumulate on the membrane surface. To enable the growth and retention of denitrifying microorganisms such as denitrifying bacteria and anaerobic ammonia-oxidizing bacteria in the MABR reactor, existing technology and device developers often use the coupling method of MABR membranes with various traditional biofilm methods and activated sludge processes to construct various types of composite or combined MABR membrane modules. Based on efficient oxygenation, this allows for the coexistence and symbiosis of various functional bacteria such as heterotrophic bacteria, nitrifying bacteria, denitrifying bacteria, and anaerobic ammonia-oxidizing bacteria, achieving stable and efficient carbon and nitrogen removal performance.

[0003] The biofilm attached to the surface of a MABR membrane has a complex structure and diverse functions, serving as the primary site for the degradation of pollutants such as organic matter and ammonia nitrogen. Within this biofilm, the mass transfer directions of oxygen, reaction metabolites, and the matrix are opposite, constituting anisotropic mass transfer. Therefore, the apparent reaction rate of pollutants is significantly correlated with biofilm thickness, especially in MABR reactors with biological nitrogen removal capabilities. On the one hand, the biofilm thickness on the MABR membrane surface needs to reach at least 450 μm to 600 μm to fully utilize the advantages of biofilm stratification and promote the smooth progress of nitrification and denitrification reactions. On the other hand, excessive biofilm proliferation, especially when its thickness exceeds 1200 μm to 1500 μm, significantly increases the mass transfer resistance between the matrix and metabolites within the biofilm, continuously reducing the biological nitrogen removal performance of the MABR. Furthermore, abnormal biofilm detachment is prone to occur, affecting reactor performance. Therefore, the biofilm thickness on the MABR membrane should not be too thin or too thick. Maintaining the optimal biofilm thickness by controlling parameters such as water circulation velocity, gas flushing intensity and frequency, and pollutant load within the reactor is crucial for stable and efficient nitrogen removal in MABR reactors. Precise control of biofilm thickness in existing MABR reactors remains challenging, and the immature in-situ online monitoring technology for biofilm thickness further complicates the optimization and control of the biofilm.

[0004] Existing research on methods for controlling biofilm thickness in MABR reactors mainly includes: ① Flow shear force control method, which increases hydraulic load and flow shear force by effluent recirculation, thereby reducing biofilm thickness, increasing biofilm density, and improving the denitrification performance of the MABR; ② Intermittent aeration flushing method, which promotes biofilm detachment from the membrane surface by intermittent air flushing at the bottom of the MABR reactor. This method is widely used in the biofilm thickness control process of MABR reactors of various sizes; ③ Chemical agent addition method, which involves adding a small amount of chemical agents to the reactor to slow down the biofilm proliferation rate, thereby controlling the biofilm thickness; ④ Starvation culture or oxygen restriction, which can inhibit biological growth and prevent excessive biofilm growth; ⑤ Protozoan predation method, which utilizes insufficient COD to allow protozoa to prey on the biofilm, forming cavities on the membrane and accelerating biofilm detachment. However, in the actual operation of MABR reactors, accurately controlling biofilm thickness remains a significant challenge.

[0005] MABR reactors typically employ an air agitation or flushing system at the bottom of the membrane module. Air is periodically introduced, and the shear force generated by the rising air bubbles removes excessively thick biofilm from the membrane surface. This prevents biofilm aggregation or buildup on the membrane surface, which can reduce treatment efficiency and achieves cleaning of the MABR membrane surface. This MABR membrane cleaning method is simple to operate, has strong flushing power, and can effectively remove excessively thick biofilm, making it a key supporting facility for the stable operation of conventional organic matter removal MABR reactors. However, for the combined MABR reactor that couples anaerobic ammonia oxidation with autotrophic denitrification, the air flushing method has obvious disadvantages: ① The air flushing process introduces oxygen into the sludge zone of the combined reactor, which inhibits the activity of Anammox bacteria and promotes NOB growth. Especially when the influent load is high, frequent air agitation or flushing will introduce more dissolved oxygen into the system; ② The strong air flushing force can cause large-area detachment of biofilm on the membrane filament surface. This has little impact on the rapidly proliferating heterotrophic bacteria in the carbon removal MABR, but it can have a significant adverse effect on nitrifying bacteria and the very slowly proliferating Anammox bacteria in the autotrophic denitrification system. In particular, when the denitrification biofilm detaches in sheets, it is not easy to recover in a short time, which makes the denitrification efficiency of the MABR reactor fluctuate drastically.

[0006] To fully leverage the advantages of MABR membrane's high oxygenation efficiency and improve the adhesion and growth performance of microorganisms to achieve high pollutant removal efficiency, various rotary MABR reactors have been developed.

[0007] For example, Chinese invention patent CN119080228B discloses a disc-shaped rotary MABR membrane module, including a main body assembly, which includes a frame assembly and membrane components; a cleaning assembly, which includes a scraping component, and a vibration component disposed within the inner cavity of the frame assembly; and a drive assembly, which includes a speed regulating component, and an active component disposed on the lower right side of the frame assembly. This invention can adjust the rotation speed of the device according to the degree of fouling of the wastewater, thereby enabling higher rotation speeds for treating highly fouled wastewater. It can also perform scraping cleaning of the outer ring of the membrane components at the lowest possible rotation speed, preventing dirt and microorganisms from adhering to the outer ring of the membrane components and affecting aeration and wastewater treatment efficiency. Furthermore, it can drive the membrane components to vibrate during wastewater treatment, thereby improving the effectiveness and efficiency of wastewater treatment and aeration.

[0008] However, this disc-shaped rotating MABR membrane module has drawbacks: ① The cleaning effect is limited. The inner ring of the disc-shaped membrane module has poor cleaning efficiency for excessively thick biofilm, affecting the overall treatment efficiency of the reactor. The scraper can only clean the outer ring, leaving the inner ring uncovered. Vibration cleaning is effective for sticky fouling. If the thick biofilm is removed by relying on the hydraulic shear force generated during the underwater rotation of the disc, the shear force on the outer ring is much higher than on the inner ring. To ensure sufficient rotational speed for removing biofilm from the outer ring, the inner ring cannot obtain enough shear force, making it easier for thick biofilm to accumulate. To ensure sufficient shear force for removing biofilm from the inner ring, the rotational speed must be significantly increased, resulting in excessive scouring of the outer ring biofilm and reducing the biomass on the membrane module. ② The mechanical transmission system is too complex, including multiple mechanical systems such as speed control components, scraping components, and vibration components. ③ Too many moving parts affect reliability. The device contains multiple motion modes such as rotation, vibration, and scraping. Vibration components suffer fatigue damage and loosening of connections under long-term vibration. The extension mechanism of the scraping component is easily blocked by impurities in sewage. ④ There are many underwater components, making maintenance difficult. Especially vulnerable components such as springs, extrusion blocks, and scrapers have complicated replacement processes. Furthermore, corrosive components in sewage pose a threat to the long-term operation of metal components. ⑤ The practicality of speed regulation is limited. The speed regulation method of switching gears via hydraulic rods has a slow response. In sewage environments, the gear meshing surfaces are easily worn, affecting transmission accuracy. Four-speed regulation may not meet the continuously changing sewage treatment needs.

[0009] Chinese invention patent application CN116969595A discloses a roller-type membrane aeration bioreactor for simultaneous denitrification and carbon removal. The device includes a tank body, a rotating drive unit fixedly connected to the top of the tank body, a central drive shaft fixedly connected to the output end of the rotating drive unit, and several bioreactor components fixedly connected to the outer wall of the central drive shaft. These bioreactor components are evenly spaced circumferentially along the outer wall of the central drive shaft and are located inside the tank body. An air inlet component is fixedly connected to the bottom of all bioreactor components, with its top fixedly connected to the bottom of the central drive shaft. A water inlet and an air inlet are fixedly connected to the bottom of the tank body's side wall, and the air inlet is connected to the air inlet component. An outlet is fixedly connected to the top of the tank body's side wall, with the inlet and outlet located on opposite sides of the tank body. A sludge discharge port is fixedly connected to the bottom wall of the tank body. The rotating composite membrane aeration component is vertically arranged, with hollow fiber membrane bundles inside nylon tubes and basalt fiber bundles outside the tubes serving as the biofilm carrier. The entire assembly rotates at 1 revolution per minute.

[0010] Chinese utility model patent CN220867192U discloses an underwater installation device for a wheel-type membrane aeration bioreactor, including a bottom fixing device, a fixing shaft, an air shaft, a wheel, a MABR membrane reactor assembly, a MABR membrane reactor main support, and a MABR membrane reactor secondary support. The bottom fixing device is fixed to the riverbed at its bottom end. The bottom end of the fixing shaft is connected to the bottom fixing device, and the top end is connected to the air shaft. Both the top and bottom ends of the air shaft are closed. The lower end of the shaft is provided with an air inlet for connecting an external air supply device. A rotary joint is connected to the upper part of the air inlet. The MABR membrane reactor assembly is placed above the rotary joint, and its two ends are fixed to the MABR membrane reactor main support and the MABR membrane reactor secondary support, respectively. The MABR membrane reactor main support and the MABR membrane reactor secondary support are arranged around the air shaft. The MABR membrane reactor secondary support is connected to the wheel. The wheeled MABR reactor is installed underwater in the river. The rotating wheel structure solves the problems of difficult installation and high cost in thick sediment environments. MABR modules (horizontal multi-layer) and rope packing (vertical arrangement) are alternately arranged on the wheel. Air in the ventilation shaft is transported to the membrane support through a rotary joint (sealed ventilation type). Rotation enhances mass transfer, biofilm renewal and synergistic purification. The aeration tail gas rotates with micro-power (no external power).

[0011] The aforementioned rotating composite membrane aeration components have the following drawbacks: ① They do not separately consider optimization and control measures for MABR biofilm thickness. These devices combine rope-type packing or basalt fiber bundles with MABR membrane filaments to form composite membrane aeration components. Their main purpose is to accelerate biofilm attachment and improve the mass exchange efficiency between the biofilm and pollutants. However, they are relatively weak in preventing the detachment of excessively proliferating biofilms. ② The purpose of rotating the membrane components is to enhance water body disturbance and optimize mass transfer, improving the forward diffusion of pollutants in wastewater and the reverse diffusion of microbial metabolites. Due to the slow rotation speed, the hydraulic shear force generated on the MABR biofilm is weak, making it difficult to shear off excessively thick biofilms. ③ For devices that use MABR membrane exhaust gas to drive the rotation of the membrane components, the driving force is small, resulting in poor stability and reliability of the membrane component rotation process. ④ The long-term operational reliability of the mechanical system is poor, maintenance complexity is high, and the durability requirements for key materials are high.

[0012] Chinese utility model patent CN221544353U discloses a rotatable membrane aeration biofilm reactor, comprising a membrane frame, a MABR membrane module, an air supply component, and a drive component. The membrane frame has upper and lower membrane frame fixing frames and upper and lower MABR membrane module fixing frames. The MABR membrane module is rotatably mounted between the upper and lower MABR membrane module fixing frames and is driven to rotate by the drive component. The MABR membrane module consists of a mounting base, a membrane tube base, a membrane tube fixing seat, a connecting sleeve, an air inlet pipe, and a MABR membrane tube. The MABR membrane tube is connected to the air inlet chamber of the membrane tube base, and one end of the air inlet pipe is connected to this air inlet chamber, while the other end is connected to the air supply component via a rotating air pipe connector. The reactor adopts a fully submerged longitudinal arrangement, and its hollow MABR membrane tube is composed of an outer layer of polyester fiber, a middle layer of heavy ion microporous membrane, and an inner layer of polyester fiber. This design, by driving the membrane module to rotate, can effectively improve the oxygen mass transfer efficiency and membrane surface utilization rate within the reactor, thereby enhancing wastewater treatment effects and helping to prevent membrane fouling.

[0013] Chinese utility model patent CN211367115U discloses a rotary MABR wastewater treatment device, which includes an oxidation tank with a rotating shaft in the center. An air storage cylinder is fitted onto the shaft, and the cylinder has a circumferentially distributed fixed frame for mounting aeration membrane components. Multiple submersible agitators are evenly spaced from bottom to top on the inner wall of the oxidation tank. The air storage cylinder is connected to the aeration membrane components via circumferentially distributed connecting pipes extending from its cylinder body, passing through the fixed frame. This device uses vertically mounted components that can rotate centrally. Combined with the multiple submersible agitators evenly spaced on the inner wall of the tank, it effectively reduces energy consumption in the water circulation process and improves the mixing effect. This design significantly accelerates water circulation efficiency and reduces energy consumption through the rotary aeration membrane components, while the submersible agitators ensure thorough mixing and high-speed flow of the substrate within the reactor, thereby significantly improving wastewater treatment efficiency.

[0014] Chinese utility model patent CN206126948U discloses a rotary MABR reactor applied in the field of water treatment technology. This reactor fixes a planar curtain-type hollow fiber membrane module to a hollow rotating shaft, which rotates with the module, and the membrane module is equipped with an exhaust valve. This hollow fiber membrane module serves as both an aeration and biological carrier. Its rotational stirring achieves substrate mixing within the reactor, and the rotational speed of the membrane module can be adjusted by changing the rotational shaft speed, thereby enhancing mass transfer and accelerating biofilm detachment. The exhaust valve allows the reactor to flexibly select between dead-end or through-flow aeration methods. The reactor adopts a central rotation method with the hollow fiber membrane module arranged vertically, and its membrane fibers arranged horizontally and can be arranged laterally or longitudinally. This design effectively reduces the energy consumption of the MABR process while enhancing mass transfer efficiency and enabling flexible control of the reactor during operation.

[0015] Chinese utility model patent CN213012198U discloses a novel mobile membrane aerated biofilm reactor (MABR), comprising a biofilm reaction module, an aeration pump, a return pump, and an influent pump. The biofilm reaction module has a reactor body, within which a hollow fiber membrane module is rotatably mounted, and is equipped with a distribution plate and a filter plate. The body also features an aeration inlet pipe, an influent pipe, and a return pipe. This mobile MABR module can be driven by a motor to rotate the center of the membrane module, thereby achieving efficient mass transfer and shear control of the biofilm thickness. This device has advantages such as small footprint, high oxygen mass transfer efficiency, low operating cost, and energy saving and environmental protection. Its modular design allows for flexible adjustment of the number of modules based on the actual organic matter concentration and biochemical performance of the wastewater, improving its adaptability and convenience.

[0016] The disadvantages of the aforementioned rotating membrane aeration unit are as follows: ① Relying on the rotation of the membrane module to control the shedding of excessively thick biofilm results in significant differences in performance between the inner and outer rings. The membrane fibers are uniformly arranged in a cylindrical shape, submerged in water, and rotate around the cylinder's axis. The large difference in hydraulic shear forces between the inner and outer rings of membrane fibers leads to significant uneven biofilm shedding. Typically, the rotation speed is adjusted based on the biofilm thickness of the outer ring membrane fibers, thus reducing the hydraulic shear force on the inner ring MABR biofilm, making it prone to excessive biofilm accumulation. ② Problems such as internal membrane fiber breakage or seal failure are difficult to detect, affecting the reactor's transfer efficiency. ③ Cleaning and maintenance of the membrane module are difficult, requiring shutdown and removal of the entire rotating structure, resulting in a cumbersome, time-consuming, and costly maintenance process. ④ There are water quality adaptability issues. For wastewater containing large amounts of fiber or suspended solids, the rotating components are prone to entanglement or blockage. ⑤ Structural complexity and mechanical reliability risks.

[0017] Chinese utility model patent CN215049010U discloses a membrane module for MABR wastewater treatment, comprising a reaction tank containing MABR wastewater treatment membrane modules. These plate-type membrane modules are distributed in a dispersed manner, which not only increases the effective utilization area within the reaction tank but also expands the treatment coverage area for wastewater. Furthermore, the rotating main shaft can rotate automatically under the action of water flow. In operation, air is supplied to the upper mounting block via the main air inlet, then enters the upper air pipe, and finally enters the membrane structure, forming an oxygen-rich area to enhance wastewater treatment efficiency. Air is also sequentially output through the lower air outlet, lower air pipe, lower mounting block, and output main air inlet. Longitudinal installation allows for central rotation, automatic wheel rotation under water flow, and multiple membrane modules can be arranged longitudinally.

[0018] The existing rotatable plate membrane modules have the following disadvantages: ① Insufficient membrane module density, large spacing between modules, and low biomass in the reactor, affecting the sufficiency of the reaction. ② Strong dependence on the rotating main shaft; the device relies on the rotation of the main shaft to achieve wastewater mixing. If the water flow is insufficient, rotation may stop, causing wastewater short-circuiting or dead zones, reducing treatment efficiency. ③ Too many continuous mechanical parts; long-term operation in a wastewater environment makes the hinges susceptible to corrosion and wear, leading to structural loosening or failure. ④ No separate control measures for excessively thick biofilms.

[0019] Chinese utility model patent CN222312877U discloses an easy-to-clean membrane aeration biofilm reactor, relating to the field of wastewater treatment technology. It includes a shell, within which a reaction chamber and a cleaning chamber are arranged. A partition and a horizontal reaction body are arranged between the reaction chamber and the cleaning chamber. The reaction body is a hollow cylinder. The partition has two rotating grooves adapted to the reaction body. The bottom surface of the reaction body is rotatably sealed to the inner wall of the shell, and the reaction body and the partition are slidably sealed together. The reaction body includes a fixed block and membrane modules. The vertical projection of the fixed block coincides with that of the partition. The membrane modules are arranged on both sides of the fixed block. A first inlet is provided at the end of the reaction chamber away from the cleaning chamber, and a first outlet is provided at the end of the reaction chamber located in the hollow part of the reaction body, communicating with the outside. This utility model facilitates cleaning of the membrane module while significantly reducing the impact of cleaning on the membrane module's working efficiency, ensuring efficient treatment of wastewater. This device is a non-continuous rotating MABR, which includes a reaction chamber and a cleaning chamber. The reaction device is a hollow cylinder that can rotate around a horizontal axis. It adopts a periodic manual rotation of 180 degrees to the cleaning chamber for cleaning, which facilitates personnel to clean the membrane modules. The cleaning methods include chemical soaking, backwashing, and ultrasonic cleaning.

[0020] The existing discontinuous rotary MABR units have the following drawbacks: ① Long-term feasibility and wear issues with the sealing structure. The sliding seal connection between the rotatable reactor and the fixed partition is the core of the unit, but its operational reliability is poor under long-term wastewater environment, biofilm adhesion, and physical friction conditions. ② Loss of effective membrane area and treatment capacity. By rotating, half of the membrane modules are in operation while the other half are being cleaned, resulting in only half of the total number of membrane modules in operation, thus significantly reducing the working capacity. ③ Complexity of cleaning operations. The cleaning chamber integrates multiple cleaning methods, but the operation process is complex, increasing the complexity of the automated control system and the burden on manual operation. ④ Potential impacts on fluid dynamics and mass transfer efficiency. Wastewater flowing through the hollow cylindrical interior may lead to uneven flow field distribution within the reactor chamber, and dead zones or short-circuiting may easily form in areas such as the corners of the reactor, affecting the contact efficiency between pollutants and the biofilm and the overall treatment effect.

[0021] In summary, although the aforementioned types of rotary MABR membrane modules and devices differ in structural design, they all reveal some key common technical bottlenecks. Firstly, regarding the core issue of biofilm thickness control, there is a common problem of uneven distribution of hydraulic shear force generated by rotation. This leads to significant differences in biofilm shearing effects between the inner and outer rings of the membrane module, making coordinated optimization difficult. Increasing the rotation speed to ensure biofilm removal from the inner ring often results in excessive scouring of the outer ring biofilm and loss of biomass; conversely, if the outer ring is prioritized, the inner ring is prone to excessively thick biofilm growth, affecting mass transfer and treatment efficiency. Secondly, in terms of mechanical system and operational reliability, structural complexity and high failure risk are common problems. Excessively long transmission chains, numerous moving parts, and susceptibility to corrosion, wear, and impurity blockage in the long-term exposure to wastewater environments lead to a series of problems such as vibration fatigue, loose connections, and seal failure. This also makes the maintenance of critical underwater components extremely difficult; replacing vulnerable parts often requires complete hoisting or shutdown, resulting in cumbersome procedures and high costs. Finally, regarding engineering applicability, there are generally insufficient adaptability to changes in water quality. Issues include susceptibility to clogging by suspended solids, dead zones caused by uneven fluid distribution, and potential operational instability due to rotary drive methods (such as weak exhaust gas drive). These common shortcomings indicate that rotary MABR technology still needs breakthroughs in areas such as precise biofilm control, long-term reliability and ease of maintenance of the mechanical system, and overall energy efficiency and cost balance. Furthermore, the aforementioned devices are all designed for the removal of organic matter and heterotrophic denitrification, without specifically considering the autotrophic denitrification process coupled with integrated MABR and anaerobic ammonia oxidation, making it difficult to meet the demands of autotrophic denitrification. Summary of the Invention

[0022] To address the aforementioned technical problems, this invention provides a spiral rotary MABR autotrophic denitrification reactor and its operation control method. By optimizing the distribution of membrane fibers in different regions of the inner and outer rings of the spiral rotary MABR membrane module, the density of the inner ring membrane fibers is reduced, minimizing the formation of excessively thick biofilms on the inner MABR membrane fibers and thus preventing sludge accumulation. Through enhanced biofilm reduction operations, the water level in the membrane reactor can be controlled to decrease, and the radial proportion of the rotating membrane module exposed above the water surface can be adjusted. Utilizing the enhanced hydraulic shear force at the gas-liquid interface during rotation, effective removal of biofilm from the inner ring of the spiral rotary reactor is achieved, enhancing the uniformity of biofilm removal from the rotating MABR membrane module and improving the overall treatment efficiency of the device. By adjusting and controlling the rotation speed of the spiral rotary MABR membrane module, the biofilm in the reactor can be effectively removed. Wastewater is uniformly mixed and can be pushed along the axial direction of the membrane module. Multiple bottom inlets enable uniform water distribution and periodic pulse inlet, achieving uniform agitation of the bottom granular sludge zone and improving autotrophic denitrification efficiency. The rotating disc extends into the center of the bottom granular sludge zone, achieving horizontal pushing of the granular sludge during its spiral rotation. Reversing the rotation direction allows for reverse horizontal pushing of the granular sludge, resulting in more uniform sludge distribution. Positioning the drive unit at the top of the tank reduces the number of underwater mechanical parts, minimizing underwater corrosion and wear, and lowering the difficulty of operation and maintenance. Modular components, quick-connect interfaces, and quick-release clips facilitate easy connection and disassembly of the MABR membrane module with the spiral rotating disc frame and hollow shaft's inlet and outlet pipes, simplifying installation, maintenance, and replacement.

[0023] To solve the above-mentioned technical problems, this invention provides a spiral rotating disc type MABR autotrophic denitrification reactor, comprising: The reaction tank is internally divided into an influent zone and a membrane reaction zone, with a composite sludge zone at the bottom of the membrane reaction zone. A spiral rotary MABR membrane module is horizontally arranged in the membrane reaction zone and can rotate around its axis under the action of a driving device. The spiral rotary MABR membrane module consists of multiple sets of composite membrane elements and a spiral rotating frame to form an equal pitch spiral surface structure. The arrangement density of the MABR membrane filaments in the composite membrane elements is higher on the outer ring than on the inner ring. A double-layer hollow rotating shaft is horizontally arranged within the membrane reaction zone. The inner ring of the spiral rotating MABR membrane module is connected to the outer peripheral wall of the double-layer hollow rotating shaft. The inner layer pipe of the double-layer hollow rotating shaft is the air inlet area connected to the gas supply system, and the outer annular area is the exhaust area. The air inlet end of the membrane fiber of the composite membrane element is connected to the air inlet area, and the air exhaust end of the membrane fiber is connected to the exhaust area.

[0024] Furthermore, the spiral turntable frame includes an inner ring support and an outer ring support in the shape of a helix with equal pitch. The inner ring support and the outer ring support are connected by a radial support rod perpendicular to the spiral axis. The composite membrane element is a fan-shaped ring with a helical surface. Multiple composite membrane elements are detachably fixed between the inner ring support and the outer ring support to form a complete equidistant helical surface.

[0025] Furthermore, the composite membrane element includes a membrane element frame, a membrane element grid plate, and MABR membrane fibers. The MABR membrane fibers are symmetrically distributed on the outer surface of the membrane element grid plate from the center line of the spiral surface to both straight edges. The end of the MABR membrane fiber near the center line of the spiral surface of the membrane element grid plate is the membrane fiber inlet end, and the end near both straight edges of the membrane element grid plate is the membrane fiber outlet end.

[0026] Furthermore, the driving device includes a drive motor and a reducer located at the top of the reaction tank. A driven gear is provided on the double-layer hollow rotating shaft, and the driving gear on the reducer is connected to the driven gear via a chain drive.

[0027] Furthermore, the double-layer hollow rotating shaft is composed of nested inner and outer tubes of different diameters, with the diameter ratio of the inner and outer tubes being 1.4:1 to 1.6:1. The front end of the inner tube extends beyond the front end of the outer tube and is connected to the air intake pipe of the air supply system through an air intake end rotary joint. The rear end of the inner tube is closed and maintains a 1 / 2 shaft diameter distance from the rear end of the outer tube. The rear end of the outer tube is connected to the exhaust pipe through an exhaust end rotary joint.

[0028] Furthermore, the water inlet area is located at one end of the long side of the membrane reaction zone, and its bottom is located in the middle of the height of the membrane reaction zone. The bottom of the water inlet area is provided with multiple water inlet branch pipes, and the bottom of the membrane reaction zone is provided with multiple sets of water inlet distributors arranged along the length of the membrane reaction zone. The water inlet branch pipes are respectively connected to the corresponding water inlet distributors. Each water inlet branch pipe is provided with a water inlet valve. The membrane reaction zone is also provided with a downwater pipe and a water outlet pipe. The downwater pipe is provided with a downwater valve to control the liquid level in the membrane reaction zone.

[0029] Furthermore, the lower rear end of the membrane reaction zone is provided with multiple sludge discharge branch pipes of different heights, and the front and rear ends of the membrane reaction zone are respectively provided with ultrasonic sludge level gauges; both the water inlet zone and the membrane reaction zone are provided with level gauges and water quality detection sensors, and the water quality parameters include at least one of pH value, temperature, ammonia nitrogen concentration, dissolved oxygen, oxidation-reduction potential, nitrite nitrogen and nitrate nitrogen.

[0030] The beneficial effects of a spiral rotary MABR autotrophic denitrification reactor are as follows: This horizontally arranged spiral rotary MABR membrane module integrates multiple functions. This module is not only a biofilm carrier and aeration unit, but its rotational motion itself simultaneously realizes the vertical mixing and horizontal axial flow of the wastewater in the reactor. Thus, it combines the advantages of complete mixing and plug flow in a single reactor. It can replace the traditional mixed liquor recirculation and independent air mixing system, realizing multiple functions such as aeration, liquid phase mixing, axial flow, gentle stirring of the sludge zone, and biofilm renewal. It replaces multiple independent units such as traditional recirculation pumps, submersible mixers, and air mixing systems, achieving a high degree of system integration, simplifying the system structure, and reducing energy consumption and maintenance complexity.

[0031] The composite membrane element features a non-uniform distribution design with a higher density of membrane fibers on the outer ring than on the inner ring. This design proactively balances the proliferation and shedding of biofilm on the outer ring, preventing excessive biofilm buildup on the inner ring. It addresses the issue of uneven hydraulic shear forces between the inner and outer rings of rotating membrane modules, which can lead to significant differences in biofilm thickness between the inner and outer rings. Combined with regular updates via "rotation speed gradation" and enhanced reduction via "water level control," this system systematically solves the industry-wide problem of uneven biofilm shedding and excessive buildup on the inner ring in rotating reactors. This ensures that the core functional area of ​​the MABR (MABR biofilm) maintains high-efficiency mass transfer over the long term.

[0032] The multiple composite membrane elements constituting the helical disc MABR membrane module employ a "sandwich" structure composite carrier: the middle layer is a grid plate for attaching anaerobic bacteria, with MABR membrane filaments symmetrically arranged on both sides. This spatial structure provides an ideal microenvironment for the stratified colonization and integrated synergistic nitrogen removal of aerobic ammonia oxidizing bacteria (AOB), anaerobic ammonia oxidizing bacteria (Anammox), and denitrifying bacteria. The rotation of the helical disc MABR membrane module achieves pure water agitation and flow propulsion, completely eliminating dissolved oxygen inhibition. The modular and top-mounted drive design ensures long-term reliable system operation. The helical disc configuration, non-uniform filament distribution, and composite carrier are deeply integrated, forming a core functional unit that integrates efficient aeration, fluid mixing, horizontal flow propulsion, and zoned biological nitrogen removal.

[0033] Using a double-layer hollow rotating shaft as the core gas path, with the inner pipe forming the air intake zone and the outer annular area forming the exhaust zone, this design enables centralized air supply and exhaust gas collection for multiple composite membrane elements distributed along a spiral path while rotating. This greatly simplifies gas path sealing and layout, resulting in high oxygen utilization and preventing the direct introduction of dissolved oxygen into the liquid phase, which is crucial for protecting anaerobic ammonia-oxidizing bacteria. Secondly, the entire membrane module adopts a modular quick-assembly design, with multiple fan-shaped annular composite membrane elements disassembled and assembled onto the spiral rotating frame, connected to the gas path branch pipes via quick-connect fittings, making installation, maintenance, and component replacement extremely convenient. Furthermore, all drive devices are located at the top of the reaction tank, using chain drive to minimize underwater moving parts, reducing corrosion, wear risks, and maintenance difficulty. The double-layer hollow rotating shaft, modular quick-assembly, and top-mounted drive complement each other, jointly constructing an optimized system engineering solution that supports the long-term stable operation of the core membrane module.

[0034] The present invention also provides an operation control method for the above-mentioned spiral rotary MABR autotrophic denitrification reactor, comprising the following steps: S001: Start the reactor and form the corresponding biofilm on the spiral rotating MABR membrane module by stepwise membrane attachment. S002: Close the sludge discharge branch pipe and the dewatering valve, continuously inject ammonia-containing wastewater into the membrane reaction zone, and supply air to the spiral rotary MABR membrane module through the air supply system, control the spiral rotary MABR membrane module to rotate continuously at the first speed, and carry out autotrophic denitrification treatment. S003: Obtain water quality detection data of the membrane reaction zone; when the water quality detection data indicates that the MABR biofilm thickness exceeds the normal range, perform a biofilm reduction operation. The biofilm reduction operation includes conventional reduction methods and enhanced reduction methods; The conventional reduction method includes: controlling the spiral rotary MABR membrane module to operate at a second speed higher than the first speed, and performing conventional reduction by enhancing the hydraulic shear force; The enhanced reduction method includes: lowering the liquid level in the membrane reaction zone, controlling the radial exposure ratio of the spiral rotating MABR membrane module, and using the sudden shear force at the gas-liquid interface and the gravity of the water film to flush away and peel off the excessively thick biofilm. S004: After the biofilm reduction operation is completed, resume normal operation.

[0035] Furthermore, in step S003: When the nitrate nitrogen formation rate reaches 10%~12%, the conventional reduction method is implemented: the rotation speed of the spiral rotary MABR membrane module is gradually increased from 2.0~6.0 rpm to 6.0~18.0 rpm and run for 5~10 minutes; When the nitrate nitrogen formation rate reaches 13%~15%, the enhanced reduction method is implemented, which includes: S0031: Stop water intake, control the rotation speed of the spiral disc MABR membrane module to 1.0~3.0 rpm, open the downwater valve, and lower the water level in the membrane reaction zone to reduce the radial exposure ratio of the spiral disc MABR membrane module to 40%-45%; S0032: Control the spiral rotary MABR membrane module to run at a speed of 1.0-3.0 rpm for 2-3 minutes, and then increase the speed to 2.0-6.0 rpm for 2-3 minutes; S0033: After the enhanced reduction operation is completed, the rotation of the spiral disc MABR membrane module is paused, the dewatering valve is closed, and after the influent is restored to the normal liquid level of the membrane reaction zone, the spiral disc MABR membrane module is resumed to run at a speed of 2.0~6.0 rpm.

[0036] This invention addresses the critical issue of biofilm thickness control in MABR (Maintenance-Assisted Bioreactor) systems by establishing a multi-mode synergistic strategy combining "conventional graded regulation" and "enhanced conditional reduction." During normal operation, the system uses a PLC to grade the rotation speed of the spiral rotor: low-speed operation achieves gentle fluid mixing and enhanced mass transfer while protecting the slowly proliferating autotrophic denitrifying bacteria biofilm; high-speed operation enhances hydraulic shear force to achieve periodic and gentle regulation of biofilm thickness. When water quality indicators suggest excessive biofilm thickness, such as a decrease in total nitrogen removal rate or an increase in nitrate nitrogen formation rate, especially when inner-zone regulation is ineffective, the system can activate an enhanced reduction mode: actively lowering the water level in the membrane reaction zone, partially exposing the spiral rotor to the water surface, controlling the radial exposure ratio to 40%–45%. Utilizing the dual enhanced effects of abrupt shear force at the gas-liquid interface and gravity scouring of the water film, the system efficiently sheds excessively thick and viscous biofilm from the inner zone. This multi-mode approach of "graded rotation speed + water level regulation" effectively solves the problems of uneven biofilm shearing between the inner and outer zones of a rotary reactor and the inhibition of anaerobic bacteria by traditional air scouring.

[0037] Furthermore, it also includes a multi-point water inlet control mode, wherein the multi-point water inlet control mode includes asymmetric water inlet control and / or periodic pulse water inlet control; The asymmetric water inlet control includes: independently adjusting the opening of the water inlet valve on each water inlet branch pipe, controlling the flow rate of each water inlet branch pipe into the corresponding water inlet distributor, forming an asymmetric multi-point water distribution mode, and the wastewater concentration in the membrane reaction zone forms an axial gradient; Periodic pulse water inlet control includes: periodically closing the water inlet valves on the water inlet branch pipes to temporarily store the water in the water inlet zone; and when the water level in the water inlet zone reaches the pulse water inlet level, sequentially or alternately opening the water inlet valves on each water inlet branch pipe to generate a pulse water flow using the high water level difference.

[0038] This invention completely eliminates the air-stirring method that introduces dissolved oxygen into the anammox sludge zone. Deeply coupled with the anammox process, it innovatively designs an asymmetric, pulse-operated, multi-point bottom water distribution system. Multiple independently controllable water distributors are installed along the length of the reactor bottom. The opening of each branch valve is adjusted by a PLC, achieving not only uniform water distribution but also an asymmetric water inlet pattern. This actively creates a pollutant concentration gradient within the reactor, enhancing the flow effect. Its most crucial function lies in the periodic pulse water inlet operation: by first closing the valves to store water and then opening them all at once, a strong pulse water flow is generated using the instantaneously formed high water level difference. This powerfully and thoroughly agitates the bottom anammox granular sludge zone. This purely hydraulic agitation method effectively prevents sludge caking and accumulation, completely avoids the introduction of dissolved oxygen, creates a stable anoxic / anaerobic environment for anammox bacteria, and protects and optimizes the bacteria.

[0039] Furthermore, it also includes a sludge horizontal plug flow control method based on sludge level feedback: The ultrasonic sludge level gauges at the front and rear ends of the membrane reaction zone monitor the sludge level in the composite sludge zone. When the difference between the sludge levels at the front and rear ends exceeds a set threshold, the spiral rotary MABR membrane module is controlled to rotate in reverse to achieve axial reciprocating homogenization of the sludge.

[0040] This invention extends the hydrodynamic function of the helical rotor to sludge zone management. By extending the edge of the helical rotor MABR membrane module into the center of the bottom granular sludge zone, it generates a horizontal thrust on the sludge during rotation, causing the sludge to move slowly along the membrane module's axial direction. To achieve uniform sludge distribution, a closed-loop feedback control mechanism is introduced: ultrasonic sludge level gauges are installed at both the front and rear of the reactor to monitor the sludge level difference in real time. When the sludge level difference exceeds a set threshold, the PLC automatically controls the drive motor to reverse, thereby switching the rotation direction of the helical rotor and causing the sludge to move in the opposite direction. This automatic directional control based on real-time sludge level feedback achieves reciprocating sludge flow and dynamic homogenization in the axial direction, effectively preventing local accumulation and dead zones, and significantly enhancing sludge-water contact and mass transfer efficiency.

[0041] Furthermore, it also includes biofilm attachment methods, including: S0011, Nitrifying biofilm attachment: Wastewater and concentrated nitrified sludge mixture are injected into the membrane reaction zone. The wastewater volume is 75% of the effective volume of the membrane reaction zone, the sludge volume is 25% of the effective volume of the membrane reaction zone, and the sludge concentration is 8.0~12.0 g / L. After that, the mixture is allowed to stand for 30~60 min. Turn on the air supply system, with an aeration pressure of 50~80kPa, an air supply flow rate of 1 / 4~1 / 3 of the design value, an influent flow rate of 1 / 3 of the design value, and control the rotation speed of the spiral rotary MABR membrane module to 2.0~3.0rpm. The water quality monitoring sensor in the membrane reaction zone continuously monitors the following: when the ammonia nitrogen removal rate first reaches 85% or higher, the influent flow rate is increased to 2 / 3 of the design value, the air supply flow rate is increased to 1 / 2 to 2 / 3 of the design value, and the rotation speed of the spiral disc MABR membrane module is 3.0 to 4.0 rpm; when the ammonia nitrogen removal rate reaches and stabilizes at 85% or higher again, the influent flow rate and air supply flow rate are increased to the design values, and the rotation speed of the spiral disc MABR membrane module is 4.0 to 6.0 rpm; when the ammonia nitrogen removal rate reaches 95% or higher, the nitrification biofilm formation process is completed. S0012, Short-cut nitrification biofilm conversion stage: The aeration pressure is adjusted to 20~40kPa, and the air supply flow rate is gradually reduced, so that the ammonia nitrogen removal rate of the water in the membrane reaction zone is reduced to 50%~60%, and the nitrification rate gradually increases and stabilizes at 70%~80%; then the aeration method is adjusted to intermittent aeration until the nitrification rate reaches more than 90%, thus completing the short-cut nitrification biofilm conversion stage; S0013, Anaerobic ammonia oxidation biofilm formation stage: Stop water intake and aeration, stop the rotation of the spiral disc MABR membrane module, and discharge the nitrified sludge; Inoculate the membrane reaction zone with anaerobic ammonia oxidation sludge at a rate of 15% to 20% of the effective volume of the membrane reaction zone. After inoculation, turn on the influent flow rate to the design value, control the spiral rotary MABR membrane module to rotate at a speed of 2.0 to 6.0 rpm, set the aeration rate to the final value of the short-cut nitrification biofilm conversion stage, and set the aeration pressure to 20 to 40 kPa. Use intermittent aeration mode. When the ammonia nitrogen removal rate reaches 90% and the total nitrogen removal rate reaches more than 80%, the anaerobic ammonia oxidation biofilm formation stage is completed.

[0042] The overall design concept and all technical measures of this invention revolve around the core objective of serving and optimizing the anammox autotrophic denitrification process, forming a comprehensive protection system from start-up to operation. In the start-up phase, a specialized three-step biofilm formation method is designed: ① nitrifying biofilm formation → ② short-range nitrifying biofilm conversion → ③ anammox biofilm inoculation, ensuring the orderly stratified colonization of aerobic and strictly anammox bacteria in space. At the operational level, all key technologies, such as pure hydraulic agitation instead of aeration, optimized shear force to prevent abnormal biofilm detachment, and the construction and maintenance of anoxic sludge zones, serve a unified purpose: minimizing the inhibition of anammox bacteria by dissolved oxygen, maintaining the structural integrity of anammox granular sludge, and creating a stable environment for its attachment and growth. This elevates this invention from an improved MABR device to a highly synergistic and deeply coupled integrated autotrophic denitrification system solution, fundamentally guaranteeing efficient and stable low-carbon denitrification performance.

[0043] This invention aims to overcome several key technical bottlenecks in the existing rotary MABR and anaerobic ammonia oxidation coupled process. Through systematic and innovative design of the reactor's core structure, operation mode, and control strategy, it provides an efficient, stable, and easy-to-maintain integrated autotrophic denitrification solution.

[0044] (1) The thickness of the biofilm was optimized and controlled in a coordinated manner between the inner and outer rings of the spiral turntable, solving the core problems of uneven shedding and excessive accumulation. Existing rotary MABR modules generally suffer from uneven distribution of hydraulic shear force between the inner and outer rings due to differences in rotational linear velocity. Increasing the rotational speed to ensure the cleanliness of the outer ring leads to insufficient shear force in the inner ring and biofilm accumulation, while decreasing the speed results in excessive scouring of the outer ring biofilm. This invention fundamentally and synergistically optimizes the biofilm growth environment in both the inner and outer rings by combining a structural design of "non-uniform distribution of membrane filaments, i.e., sparse inside and dense outside" with a multi-mode control strategy of "rotational speed grading + water level regulation". Non-uniform filament distribution reduces the substrate for excessive biofilm proliferation in the inner ring from the source; conventional gradational rotational speed regulation allows for periodic and gentle renewal; and when the inner ring biofilm is still too thick, the unique "lower water level, semi-submerged rotation" enhanced reduction operation can utilize the abrupt shear force at the gas-liquid interface to specifically and efficiently peel off the inner ring biofilm. This effectively overcomes the shortcomings of existing technologies where "the difference in biofilm shedding effects between the inner and outer rings is significant and difficult to optimize synergistically".

[0045] (2) It significantly improves the long-term reliability of the device and greatly reduces the difficulty of maintenance, solving the pain points of mechanical complexity and underwater maintenance difficulties. Existing rotary MABR devices often suffer from problems such as excessively long drive chains, numerous moving parts, susceptibility to corrosion and damage of critical underwater components, and the need for overall hoisting for maintenance. This invention fundamentally simplifies and optimizes the mechanical structure through a top-mounted drive design, modular quick-install composite membrane elements, and a simple double-layer hollow shaft centralized air supply and exhaust system. This move removes most moving parts and vulnerable connection points from the wastewater environment or designs them for quick disassembly, thereby significantly reducing the risk of corrosion, wear, and failure of underwater components. It simplifies and expedites routine inspections, partial replacements, and maintenance, effectively addressing the shortcomings of existing devices, such as "common structural complexity and high failure risk" and "extremely difficult underwater component maintenance."

[0046] (3) It perfectly fits and optimizes the anaerobic ammonium oxidation autotrophic denitrification process, completely avoids dissolved oxygen inhibition, and improves denitrification efficiency and stability. Existing MABR coupled with anammox systems typically uses bottom air agitation to mix sludge or flush biofilm, which introduces dissolved oxygen, severely inhibiting the activity of anammox bacteria and promoting the growth of nitrite oxidizing bacteria. This invention employs an asymmetric pulsed influent pure hydraulic agitation system to achieve sludge mixing, utilizing the fluid propulsion of the spiral rotor itself to replace mechanical stirring. Simultaneously, biofilm control relies entirely on hydraulic shear, eliminating the need for aeration and flushing. These designs create a stable anoxic / anaerobic environment for the attachment and growth of anammox bacteria. This directly addresses and solves the key deficiency of existing technologies—that "air flushing introduces oxygen into the sludge zone of the combined reactor, inhibiting the activity of anammox bacteria"—ensuring the efficient and stable operation of the autotrophic denitrification pathway.

[0047] (4) It integrates multiple flow states and functions into one, which simplifies the system configuration, reduces energy consumption, and enhances the ability to resist shock loads. Existing technologies often require multiple independent units or auxiliary systems, such as mixed liquor reflux pumps, submersible mixers, and air mixing systems, to achieve functions such as complete mixing, flow propulsion, agitation, and reflux, resulting in complex systems and high energy consumption. This invention, through the rotation of a single component—a spiral rotating membrane module—simultaneously achieves vertical mixing of wastewater, axial flow propulsion, and flexible agitation of the sludge zone, effectively replacing multiple subsystems. This integrated design not only simplifies the process flow and equipment configuration but also achieves significant energy savings by avoiding air agitation and greatly reducing the energy consumption required for liquid reflux. Simultaneously, the combined flow pattern of complete mixing and flow propulsion within the reactor provides both good substrate distribution and resistance to shock loads, thus addressing the problem of "complex system equipment configuration and high operating energy consumption" caused by existing technologies attempting to achieve multiple functions.

[0048] In summary, this invention fundamentally optimizes the reactor's hydrodynamic characteristics and biofilm carrier structure through the integrated functional design of the "spiral rotary composite membrane module"; significantly improves the reliability and maintainability of the device through system integration of "modular quick assembly and centralized gas supply"; creates a stable, efficient, and uninhibited growth environment for core functional bacteria, especially anaerobic ammonia oxidizing bacteria, through intelligent control strategies such as "multi-mode biofilm regulation" and "pure water sludge agitation"; and achieves adaptive optimization of the system through technologies such as "sludge level feedback propulsion". These innovations work synergistically to successfully solve a series of prominent problems in existing technologies, such as difficult biofilm control, high energy consumption, system complexity, maintenance difficulties, and dissolved oxygen inhibition of anaerobic ammonia oxidizing bacteria. While achieving efficient and low-carbon nitrogen removal, it significantly improves the stability, economy, and ease of operation of the entire process, demonstrating outstanding technical advantages and application prospects.

[0049] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the reactor structure of the present invention; Figure 2 This is a longitudinal cross-sectional view of the reactor of the present invention; Figure 3 This is an axial orthographic projection view of the spiral rotating disk frame of the spiral rotating disk type MABR membrane module of the present invention. Figure 4 This is an axial orthographic projection view of the spiral rotary MABR membrane module of the present invention; Figure 5 This is a schematic diagram of the axial orthographic projection of the composite membrane element of the present invention.

[0051] In the attached diagram: 1—Reaction tank; 2—Inlet water zone; 3—Membrane reaction zone; 4—Composite sludge zone; 5—Spiral rotary MABR membrane unit zone; 6—Spiral rotary MABR membrane module; 7—Double-layer hollow shaft; 8—Exhaust zone; 9—Air inlet zone; 10—Spindle air inlet bearing seat; 11—Air inlet rotary joint; 12—Hollow shaft inner support; 13—Spindle exhaust end bearing seat; 14—Exhaust end rotary joint; 15—Spindle mechanical seal; 16—Spindle support wheel; 17—Chain; 18—Reducer; 19—Drive motor; 20—Inlet water pipe; 21—Inlet water flow meter; 22—Inlet water quality sensor; 23—Inlet water quality secondary meter; 24—Inlet branch pipe; 25—Pre-membrane inlet valve; 26—Middle-section inlet valve of the membrane zone. 27—Inlet valve for the rear section of the membrane zone; 28—Water distributor for the front section of the membrane zone; 29—Water distributor for the middle section of the membrane zone; 30—Water distributor for the rear section of the membrane zone; 31—Aeration blower; 32—Air inlet pipe; 33—Air inlet pipe flow meter; 34—Air inlet pipe pressure sensor; 35—Exhaust pipe; 36—Exhaust pipe flow meter; 37—Outlet pipe; 38—Drainage pipe; 39—Drainage valve; 40—Sludge discharge branch pipe; 41—Sludge discharge main pipe; 42—Ultrasonic level gauge for the inlet zone; 43—Ultrasonic level gauge for the membrane reaction zone; 44—Water quality sensor for the membrane reaction zone; 45—Secondary water quality meter for the membrane reaction zone; 46—Ultrasonic sludge level gauge for the front section of the membrane zone; 47—Ultrasonic sludge level gauge for the rear section of the membrane zone; 48—Bottom chamfer of the membrane reaction zone; 49—Variable frequency controller; 50—PLC controller; 601—Spiral turntable frame; 602—Hollow shaft inlet branch pipe; 603—Hollow shaft exhaust branch pipe; 604—Hollow shaft inlet branch pipe valve; 605—Air pipe quick connector; 606—Hollow shaft exhaust branch pipe valve; 607—Composite membrane element; 608—Composite membrane element frame; 609—Membrane fiber inlet end; 610—Membrane fiber inlet end connecting assembly; 611—Membrane fiber exhaust end; 612—Composite membrane element grid plate; 613—MABR membrane fiber; 614—Membrane module frame snap fastener. Detailed Implementation

[0052] Referring to the accompanying drawings, specific embodiments of the present invention will be described in detail.

[0053] Reference Figures 1 to 5 This invention provides an embodiment of a spiral rotary MABR autotrophic denitrification reactor.

[0054] A spiral rotating disc type MABR autotrophic denitrification reactor includes a reaction tank 1, a spiral rotating disc type MABR membrane module 6, and a double-layer hollow rotating shaft 7.

[0055] The reaction tank 1 can be made of reinforced concrete or steel, and its internal space is divided into an inlet zone 2 and a membrane reaction zone 3. The inlet zone 2 is located at one end of the long side of the membrane reaction zone 3. Wastewater to be treated enters the inlet zone 2 from the top of the tank via an inlet pipe 20. An inlet flow meter 21 and a valve are installed on the inlet pipe 20. An inlet zone level gauge, preferably an ultrasonic level gauge 42, is installed at the top of the inlet zone 2 for real-time monitoring of the water level. This level can be controlled between the normal inlet level and the pulse inlet level, enabling pulse agitation of the sludge zone at the bottom of the membrane reaction zone 3 by both conventional asymmetric and pulse inlet water flow. The inlet flow rate and inlet zone level data are input into a PLC. The top of the inlet zone 2 is 1.0~1.5m higher than the top of the membrane reaction zone 3, allowing for buffering of the inlet water as needed. The bottom of the inlet zone 2 is located near the middle of the height of the membrane reaction zone 3, and is more than 1.0m higher than the bottom of the membrane reaction zone 3, so as to facilitate the arrangement of the inlet branch pipe 24 of the membrane reaction zone.

[0056] The membrane reaction zone 3 is the main body of the reactor and is a rectangular pool. Preferably, a chamfer 48 is provided at the bottom of the membrane reaction zone along the length of the pool. The chamfer is arc-shaped, so that the longitudinal cross-section of the membrane reaction zone 3 presents a "U" shape. The arc surface of the chamfer 48 at the bottom of the membrane reaction zone 3 is parallel to the outer contour of the spiral rotating MABR membrane module 6 located in the middle of the membrane reaction zone 3. Furthermore, the distance between the chamfer 48 and the outer surface of the spiral rotating MABR membrane module 6 is consistent with the distance between the sidewall of the membrane reaction zone 3 and the outer surface of the spiral rotating MABR membrane module 6. The membrane reaction zone 3 is divided into upper and lower regions: the upper region is the spiral rotating MABR membrane device region 5, and the lower region is the composite sludge region 4. The effective volume ratio of these two regions is 3:1 to 5:1.

[0057] The spiral rotary MABR membrane module 6 is horizontally arranged within the spiral rotary MABR membrane device area 5 of the membrane reaction zone 3, and can rotate around its axis under the action of the driving device. The axis of the spiral rotary MABR membrane module 6 is parallel to the bottom of the tank, and its orthogonal projection along the axial direction is a concentric ring. The outer diameter of the concentric ring is 1.0~5.0m, the inner diameter is 0.3~0.8m, and the pitch is 0.2~0.6m. The spiral rotary MABR membrane module 6 consists of multiple sets of composite membrane elements 608 and a spiral rotary frame 601 forming an equal pitch spiral surface structure. The membrane fiber arrangement density of the composite membrane element 607 is higher on the outer ring than on the inner ring, which minimizes the formation of excessively thick biofilm on the inner ring membrane fibers and avoids sludge accumulation.

[0058] A double-layer hollow rotating shaft 7 is horizontally arranged within the membrane reaction zone 3. Preferably, the double-layer hollow rotating shaft 7 is a cylindrical hollow rotating shaft made of 304 stainless steel, and is horizontally arranged in the middle of the tank along the length of the membrane reaction zone 3. The inner ring of the spiral rotating MABR membrane module 6 is connected to the outer peripheral wall of the double-layer hollow rotating shaft 7. The inner pipe of the double-layer hollow rotating shaft 7 is the air inlet zone 9 connected to the air supply system, and the outer annular area is the exhaust zone 8. The membrane fiber air inlet end 609 of the composite membrane element 607 is connected to the air inlet zone 9, and the membrane fiber exhaust end 611 is connected to the exhaust zone 8. The double-layer hollow rotating shaft 7 has its front end near the water inlet zone 2, which is the air inlet end. It is fixed to a support member in the middle of the inner wall of the membrane reaction zone 3 adjacent to the water inlet zone 2 via a bearing seat 10. The rear end of the double-layer hollow rotating shaft 7 is the exhaust end, which passes through the inner wall of the membrane reaction zone 3 away from the water inlet zone 2 and is fixed to a support member in the middle of the outer wall of the pool via a bearing seat 13. A mechanical seal 15 is installed where the double-layer hollow rotating shaft 7 passes through the pool wall of the membrane reaction zone 3 to ensure a tight seal between the shaft and the pool wall, allowing the shaft to rotate freely. Simultaneously, a rotating shaft support wheel 16 is installed on the inner side of the pool where the shaft passes through the pool wall to support the double-layer hollow rotating shaft 7 and provide a certain damping effect to ensure smooth shaft rotation.

[0059] At this point, the rotating disc-type MABR membrane module 6 with equal pitch helical surface integrates multiple functions. It is not only a biofilm carrier and aeration unit, but its rotational motion also realizes the vertical mixing and horizontal axial flow in the membrane reaction zone 3. Furthermore, through the density design of the MABR membrane filaments 613, it actively balances the proliferation and shedding of the inner and outer rings of biofilm from a structural perspective, preventing the accumulation of the inner ring of biofilm afterward. With the double-layer hollow rotating shaft 7 as the core air passage, it realizes centralized air supply and exhaust gas collection for multiple composite membrane elements 607 distributed along the spiral line in the rotating state, which greatly simplifies the sealing and layout of the air passage.

[0060] In some embodiments, the spiral turntable frame 601 includes an inner ring support and an outer ring support in the shape of a helix with equal pitch. Preferably, the inner ring support and the outer ring support are made of stainless steel, and their pitch is 0.2~0.6m. The inner ring support and the outer ring support are connected by radial support rods perpendicular to the spiral axis. Preferably, a set of support rods is provided every 45° of spiral, and the support rods are made of stainless steel angle steel. Each set of radial support rods consists of two right angle steels joined together to form a "T"-shaped component, ensuring that the inner and outer ring supports stably form a helical surface with equal pitch. The composite membrane element 607 is a fan-shaped annulus with a helical surface. Multiple composite membrane elements 607 are detachably fixed between the inner ring support and the outer ring support to form a complete equidistant helical surface. Further, the inner ring support of the spiral turntable frame 601 is welded to the outer surface of the double-layer hollow rotating shaft 7, and all radial support rods are kept perpendicular to the outer surface of the hollow rotating shaft 7. Preferably, multiple quick-release membrane module frame buckles 614 are evenly arranged on the outer ring bracket and radial support rod of the spiral turntable frame 601 to fix each composite membrane element 607 to the spiral turntable frame 601, so that the spiral turntable MABR membrane module 6 forms a spiral surface with equal pitch.

[0061] Furthermore, the composite membrane element 607 includes a membrane element frame 608, a membrane element grid plate 612, and MABR membrane fibers 613. Each composite membrane element 607 has a 45-degree helical surface, and its inner and outer helical diameters and pitches are the same as those of the helical turntable frame 601.

[0062] The membrane element frame 608 is made of 304 stainless steel. Its orthographic projection is a fan-shaped ring with a central angle of 45 degrees. It is prefabricated or machined into a 45-degree helical surface according to the pitch of the spiral turntable frame 601. The outer circumference of the membrane element frame 608 is 10-20 mm smaller than the size of each fan-shaped ring in the spiral turntable frame 601, which facilitates the installation and fixing of the membrane element.

[0063] The membrane element grid plate 612 is a PVC grid plate with a thickness of 30-50mm. The inner side length of the square grid is 25-65mm, the grid rib thickness is 3-8mm, and the opening rate is 60%-80%. The inner mesh sidewalls of the grid plate are sandblasted to form a uniformly roughened surface, which is conducive to the attachment and growth of microorganisms. This leads to the formation of a composite denitrification biofilm, mainly composed of anaerobic ammonia-oxidizing bacteria and including denitrifying bacteria, on the inner wall of the mesh of the membrane element grid plate 612. Furthermore, the membrane element grid plate 612 is manufactured by on-site hot bending of a fan-shaped flat PVC grid plate or by pre-molding. Each grid plate has a 45-degree spiral surface with the same pitch as the membrane element frame 608. The membrane element frame 608 and the membrane element grid plate 612 are firmly bonded together using high-strength structural adhesive.

[0064] The MABR membrane filament 613 is a silicone membrane or a composite membrane with a dense coating. The material of the membrane or the coating is polydimethylsiloxane or methylphenyl silicone rubber. The inner diameter of the membrane filament is 0.5mm~1.5mm, and the wall thickness is 0.25mm~0.5mm. The MABR membrane filament 613 can be a single filament or a bundle of filaments, with a quantity of 1~20 filaments. Two filaments or two bundles of filaments form a group. The MABR membrane filaments 613 are symmetrically distributed on the outer surface of the membrane element grid plate 612, meandering from the center line of the spiral surface to both straight edges, and parallel to the center line. The MABR membrane filaments 613 are fixed to the composite membrane element grid 612 by binding with nylon thread. Through this membrane filament arrangement, the membrane filament distribution density in the inner and outer regions of the composite membrane element 607 is different, with the membrane distribution density in the outer ring being 30%~40% higher than that in the inner ring, which minimizes the sludge accumulation caused by excessively thick biofilm formation on the inner membrane filaments.

[0065] The end of the MABR membrane filament 613 closest to the centerline of the spiral surface of the membrane element grid plate 612 is the membrane filament air inlet end 609. The membrane filament air inlet end 609 is close to the inner spiral ring. Two sets of symmetrical MABR membrane filaments 613 are gathered together through the membrane filament air inlet end connecting assembly 610, and then connected to the hollow shaft air inlet branch pipe 602 via the air pipe quick connector 605 and the hollow shaft air inlet branch pipe valve 604 in sequence. The end closest to the straight edge on both sides of the membrane element grid plate 612 is the membrane filament exhaust end 611. The membrane filament exhaust end 611 of the MABR membrane filament 613 is parallel to the straight generatrix. The membrane filament exhaust end 611 of each set of MABR membrane filaments is connected to the hollow shaft exhaust branch pipe 603 via the air pipe quick connector 605 and the hollow shaft exhaust branch pipe valve 606 in sequence towards the inner spiral ring. The hollow shaft inlet branch valve 604 and the hollow shaft exhaust branch valve 606 are both ball valves made of stainless steel or copper; the hollow shaft inlet branch 602 and the hollow shaft exhaust branch 603 are both made of 304 stainless steel. Preferably, two sets of MABR membrane fibers 613 are arranged on both sides of each composite membrane element 607.

[0066] Furthermore, the hollow shaft intake branch pipe 602 passes vertically through the pipe wall of the exhaust zone 8 and connects to the intake zone 9 of the inner layer of the double-layer hollow shaft 7; the hollow shaft exhaust branch pipe 603 is perpendicular to the outer wall of the hollow shaft 7 and connects to the exhaust zone 8 of the outer layer of the double-layer hollow shaft 7. The connection points of the hollow shaft intake branch pipe 602 and the hollow shaft exhaust branch pipe 603 on the double-layer hollow shaft are all spirally distributed.

[0067] In some embodiments, the double-layer hollow shaft 7 is composed of nested inner and outer tubes of different diameters. Preferably, the inner and outer tubes are made of stainless steel and are coaxially arranged. The diameter ratio of the inner and outer tubes is 1.4:1 to 1.6:1, thereby dividing the interior of the hollow shaft 7 into two regions: an inner cylindrical region forming the air intake region 9 and an outer annular region forming the exhaust region 8. The two regions are fixed by multiple sets of hollow shaft inner supports 12. The front end of the inner tube extends beyond the front end of the outer tube and is connected to the air intake pipe 32 of the air supply system via an air intake end rotary joint 11. The rear end of the inner tube is closed and maintains a 1 / 2 shaft diameter distance from the rear end of the outer tube. The rear end of the outer tube is connected to the exhaust pipe 35 via an exhaust end rotary joint 14.

[0068] Furthermore, an aeration blower 31 is installed outside the MABR reactor 1, which is connected to the rotary joint 11 at the air inlet end of the rotating shaft via an air inlet pipe 32. This allows air to enter the hollow rotating shaft air inlet zone 9 inside the double-layer hollow rotating shaft 7, thereby supplying air to the spiral rotating MABR membrane module. Oxygen in the air enters the MABR biofilm through molecular diffusion within the MABR membrane and can be utilized by aerobic ammonia-oxidizing bacteria (AOB) and other microorganisms therein, oxidizing ammonia nitrogen in the wastewater into nitrite nitrogen, thus completing the short-cut nitrification reaction. An air inlet pipe flow meter 33, an air inlet pipe pressure sensor 34, and a valve are installed on the air inlet pipe 32. The air inlet flow rate and pressure data are transferred to the PLC controller 50.

[0069] The exhaust gas emitted from the spiral rotary MABR membrane module 6 is collected in the exhaust zone inside the double-layer hollow rotating shaft 7, and then enters the exhaust pipe 35 through the rotary joint 14 at the exhaust end of the shaft, and is then discharged into the atmosphere. An exhaust pipe flow meter 36 and a valve are installed on the exhaust pipe 35, and the exhaust flow data is transferred to the PLC controller 50.

[0070] In some embodiments, the driving device includes a drive motor 19 and a reducer 18 located at the top of the reaction tank. A driven gear is provided on the double-layer hollow rotating shaft 7, and the driving gear on the reducer 18 is connected to the driven gear via a chain 17. In this case, the drive motor 19 drives the driving gear to rotate, which in turn drives the driven gear to rotate via the chain 17, thereby rotating the double-layer hollow rotating shaft 7. The drive motor 19, under the control of the frequency converter 49, achieves speed regulation and forward / reverse rotation adjustment, thus enabling the spiral rotary MABR membrane module 6 to achieve different rotational speeds and rotational switching. Preferably, the ratio of the number of driving gears to driven gears is 1:2 to 1:3; the drive motor 19 is a 4-pole three-phase asynchronous frequency converter motor, and the reducer 18 is a gear reducer with a speed ratio of 40:1. The frequency converter 49 is a vector-type frequency converter with a low-speed frequency of 20-25Hz and a high-speed frequency of 50Hz, connected to the PLC controller 50 for program control by the PLC.

[0071] Using this method, when the helical disc MABR membrane module 6 operates continuously at a low speed (controlled within the range of 2.0~6.0 rpm), it can generate flexible and uniform mixing and agitation of wastewater layers at different depths in the tank. Simultaneously, the continuously rotating helical disc surface can exert an axial pushing effect on the wastewater, resulting in more uniform mixing of wastewater in all areas of the tank and enhancing the reactor's shock resistance. Continuous low-speed rotation also enhances the liquid film renewal rate on the MABR biofilm surface, promoting mass transfer within and outside the MABR biofilm, which helps improve reaction efficiency. Furthermore, this liquid film renewal is more uniform and gentle, effectively preventing abnormal detachment of the slowly proliferating autotrophic denitrification biofilm. When the helical disc MABR membrane module 6 operates at a higher speed (controlled within the range of 6.0~18.0 rpm), it subjectes the MABR biofilm to greater hydraulic shear force, thus facilitating normal biofilm renewal and detachment, preventing excessive biofilm proliferation, which would reduce the mass transfer rate and affect the autotrophic denitrification reaction efficiency.

[0072] The sludge in the composite sludge zone 4 below membrane reaction zone 3 is mainly granular anammox sludge, including suspended anammox sludge, a small amount of heterotrophic denitrification sludge, and aged and detached MABR biofilm. During normal operation, the anammox bacteria in composite sludge zone 4 can utilize ammonia nitrogen in the influent and nitrite nitrogen produced by short-cut nitrification by aerobic ammonia oxidizing bacteria (AOB) in the MABR biofilm at a ratio of 1:1 to 1:1.32 to perform anammox reactions, converting ammonia nitrogen into nitrogen gas and a small amount of nitrate nitrogen, thereby achieving total nitrogen removal. The heterotrophic denitrifying bacteria in composite sludge zone 4 can utilize a small amount of organic matter in the influent and endogenous organic matter from dead bacteria as carbon sources to convert the small amount of nitrate nitrogen produced by anammox reactions and the nitrate nitrogen produced by nitrite oxidizing bacteria (NOB) in the MABR biofilm into nitrogen gas through denitrification reactions, thereby improving the overall nitrogen removal efficiency of the reactor.

[0073] The lower part of the spiral disc MABR membrane module 6 extends into the composite sludge zone 4. During rotation, it can gently agitate the sludge in the upper part of the sludge zone. While maintaining a good loose state in the granular sludge zone and effectively releasing nitrogen bubbles generated between sludge particles, it can effectively prevent the granular sludge from being broken up by the strong shear force of mechanical agitation. This maintains the good particle shape of the granular sludge and avoids the inhibitory effect of dissolved oxygen introduced by air agitation in conventional MABR reactors on anaerobic ammonia oxidizing bacteria. At the same time, during the rotation of the spiral disc, it can generate an axial driving force on the sludge zone, so that the sludge moves slowly laterally, promotes uniform mixing in the sludge zone, strengthens sludge-water contact, improves mass transfer of pollutants and metabolites, and thus improves the denitrification reaction efficiency.

[0074] In some embodiments, the water inlet zone 2 is located at one end of the long side of the membrane reaction zone 3, and the bottom of the water inlet zone 2 is located at the middle part of the height of the membrane reaction zone 3. A plurality of water inlet branch pipes 24 are arranged at the bottom of the water inlet zone 2, and a plurality of groups of water inlet distributors arranged along the length direction of the membrane reaction zone 3 are arranged at the bottom of the membrane reaction zone 3. The water inlet branch pipes 24 are respectively connected to the corresponding water inlet distributors, and a water inlet valve is arranged on each water inlet branch pipe 24. Further, all the water inlet valves are electric ball valves, which can complete opening, closing or opening degree adjustment operations under the control of a PLC. By adjusting the opening, closing and opening degree of different valves, an asymmetric multi-point water distribution mode for different regions of the membrane zone can be realized, so as to cope with the impact of different inlet water loads; meanwhile, the zoned multi-point water distribution method can fully and uniformly stir the granular sludge at the bottom of the composite sludge zone 4, enhance mass transfer, prevent sludge accumulation, reduce reaction dead zones, and improve the operation stability and reliability of the reactor. By temporarily closing the water inlet valves on the water inlet branch pipes to increase the water level in the water inlet zone 2, and then sequentially or alternately opening the water inlet branch pipe valves in different regions to form a pulse-type multi-point water inlet mode, the stirring effect on the sludge at the bottom of the composite sludge zone can be enhanced, sludge accumulation and caking can be prevented, and the overall denitrification efficiency of the reactor can be improved.

[0075] Further, three groups of water inlet distributors are arranged according to their positions in the tank of the membrane reaction zone 2, which are sequentially a front-section membrane zone distributor 28, a middle-section membrane zone distributor 29 and a rear-section membrane zone distributor 30, wherein the front-section membrane zone distributor 28 is adjacent to the water inlet zone 2. The main pipes and branch pipes of the three groups of distributors all adopt a "feng-shaped" structure, and downward water outlet nozzles are uniformly arranged on the branch pipes, so as to realize multi-point uniform water distribution in the region. A front-section membrane zone water inlet valve 25 is arranged on the water inlet branch pipe 24 connected to the front-section membrane zone distributor 28, a middle-section membrane zone water inlet valve 26 is arranged on the water inlet branch pipe 25 connected to the middle-section membrane zone distributor 29, and a rear-section membrane zone water inlet valve 27 is arranged on the water inlet branch pipe 24 connected to the rear-section membrane zone distributor 30.

[0076] Further, a descending pipe 38 and a water outlet pipe 37 are also arranged on the membrane reaction zone 3. The sewage treated by the MABR reactor is discharged to a subsequent unit through the water outlet pipe 37, and the water outlet pipe 37 is arranged at the upper part of the short-side side wall of the membrane reaction zone 3 tank opposite to the water inlet zone. A water descending valve 39 is arranged on the descending pipe 38 to control the liquid level in the membrane reaction zone 3. Further, a membrane reaction zone liquid level gauge is arranged at the top of the tank of the membrane reaction zone 3, preferably a membrane reaction zone ultrasonic liquid level gauge 43, which detects the water level in the tank in real time, and transmits the detection value to the PLC controller 50. Combined with the opening and closing of the water descending valve 39, it can be used to control the descending water level in the enhanced stripping operation of an excessively thick biofilm on MABR membrane modules.

[0077] The drainage valve 39 is an electric ball valve controlled by a PLC. Opening the valve discharges the upper and middle sections of wastewater in membrane reaction zone 3 to the wastewater equalization tank outside the MABR reactor, thus achieving a controllable and rapid reduction of the water level in membrane reaction zone 3. After the water level in membrane reaction zone 3 drops, the upper and middle sections of the spiral rotor MABR membrane module 6 are exposed above the water surface. The radial exposure ratio of the membrane module 6 discs (i.e., the ratio of the height of the air-exposed portion at the top of the spiral rotor to the outer diameter of the rotor) is controlled at 40%~45%. During the continuous rotation of the spiral rotor membrane module 6 in a fully submerged state, the shear force on its surface originates only from the viscous friction between the rotor and the surrounding water. This shear force is evenly distributed and has a low value, resulting in a more gentle stress environment for the biofilm. During continuous rotation, the semi-submerged spiral rotating membrane module introduces two new sources of shear force on its rotating surface. One is the abrupt shear force at the water-surface interface, where the biofilm experiences a sudden change in the water-air medium when the disc enters or exits the water, resulting in intense local shear stress due to surface tension and inertial forces. The other is the gravity scouring of the water film; after the disc exits the water surface, the surface water film flows downward under gravity, creating a continuous scouring force on the biofilm. Both of these shear forces are relatively strong and can effectively reduce excessively thick biofilms and sticky biofilms that are difficult to detach.

[0078] In some embodiments, the lower rear end of the membrane reaction zone 3 is provided with multiple sludge discharge branch pipes 40 of different heights. Valves are installed on the sludge discharge branch pipes 40. The multiple sludge discharge branch pipes 40 converge into the sludge discharge main pipe 41, allowing for sludge discharge operations at different locations in the composite sludge zone 4 as needed, ensuring a normal amount of composite sludge in the tank. Ultrasonic sludge level gauges are respectively installed at the front and rear ends of the membrane reaction zone. The one at the front end of the membrane reaction zone is a front section ultrasonic sludge level gauge 46, and the one at the rear end is a rear section ultrasonic sludge level gauge 47. These gauges can detect the sludge level in different sections of the composite sludge zone 4 at the bottom of the membrane reaction zone 3, and the detected values ​​are transmitted to the PLC controller.

[0079] At this point, when the average sludge level in different areas of the composite sludge zone 4 exceeds the set height value, the upper sludge discharge branch valve is opened to discharge low-density flocculent sludge and aged, detached biofilm, maintaining a stable sludge volume in the composite sludge zone. Furthermore, during the rotation of the spiral rotary MABR membrane module 6, the spiral disc extending into the composite sludge zone 4 exerts a lateral pushing effect on the sludge, causing it to move slowly and continuously towards one end of the membrane reaction zone 3. The sludge levels in the front and rear sections of the membrane zone are detected by the ultrasonic sludge level gauge 46 at the front and 47 at the rear, respectively. When the difference between the two sludge levels exceeds the set limit, the PLC controller 50 controls the drive motor 19 to rotate in the opposite direction, thereby driving the spiral rotary MABR membrane module 6 to rotate in the opposite direction, causing the sludge to move slowly towards the other end of the membrane reaction zone 3. By detecting the sludge level difference, the spiral rotary MABR membrane module 6 is automatically switched between forward and reverse rotation, promoting uniform lateral mixing of the sludge and improving the activity of the composite sludge zone. When a typical spiral rotary MABR membrane module 6 is arranged in a right-hand spiral configuration, the spiral surface rotates counterclockwise, generating a thrust towards the front end of the membrane reaction zone (i.e., the inlet end); when the spiral surface rotates clockwise, it generates a thrust towards the rear end of the membrane reaction zone (i.e., the outlet end).

[0080] In some embodiments, the inlet water zone 2 and the membrane reaction zone 3 are further equipped with water quality detection sensors, and the water quality parameters include at least one of pH value, temperature, ammonia nitrogen concentration, dissolved oxygen, oxidation-reduction potential, nitrite nitrogen, and nitrate nitrogen. Further, the inlet water zone 2 is equipped with an inlet water quality detection sensor 22 for real-time detection of the pH value, temperature, and ammonia nitrogen (NH4+-N) concentration of the inlet water. The measurement signals are converted into standard signals by a matching inlet water quality detection secondary meter 23 and transmitted to the PLC controller 50.

[0081] A multi-parameter membrane reaction zone water quality sensor 44 is installed in the upper part of the rear section (i.e., near the outlet end) of the membrane reaction zone 3. It can detect key water quality indicators such as dissolved oxygen (DO), pH value, oxidation-reduction potential (ORP), ammonia nitrogen (NH4+-N), nitrite nitrogen (NO2--N) and nitrate nitrogen (NO3--N) in real time. The measurement signal is converted into a standard signal by the matching membrane reaction zone water quality detection secondary meter 45 and transmitted to the PLC controller 50.

[0082] The present invention also provides an operation control method for the above-mentioned spiral rotary MABR autotrophic denitrification reactor, comprising the following steps: S001: Start the reactor and form the corresponding biofilm on the spiral rotating MABR membrane module by stepwise membrane attachment. S002: Close the sludge discharge branch pipe and the dewatering valve, continuously inject ammonia-containing wastewater into the membrane reaction zone, and supply air to the spiral rotary MABR membrane module through the air supply system, control the spiral rotary MABR membrane module to rotate continuously at the first speed, and carry out autotrophic denitrification treatment. S003: Obtain water quality detection data of the membrane reaction zone; when the water quality detection data indicates that the MABR biofilm thickness exceeds the normal range, perform a biofilm reduction operation. The biofilm reduction operation includes conventional reduction methods and enhanced reduction methods; The conventional reduction method includes: controlling the spiral rotary MABR membrane module to operate at a second speed higher than the first speed, and performing conventional reduction by enhancing the hydraulic shear force; The enhanced reduction method includes: lowering the liquid level in the membrane reaction zone, controlling the radial exposure ratio of the spiral rotating MABR membrane module, and using the sudden shear force at the gas-liquid interface and the gravity of the water film to flush away and peel off the excessively thick biofilm. S004: After the biofilm reduction operation is completed, resume normal operation.

[0083] The present invention provides a first embodiment of the operation method of the above-mentioned spiral rotary MABR autotrophic denitrification reactor.

[0084] After a stable biofilm forms on the spiral rotating disc MABR membrane module inside the reactor, the conventional operation mode of the spiral rotating disc MABR autotrophic denitrification reactor is as follows: ① Ammonia-containing wastewater is transported to MABR reactor 1 through inlet pipe 20, and the valve of sludge discharge branch pipe 40 and the downwater valve 39 are closed.

[0085] Furthermore, ammonia-containing wastewater enters from the top of the inlet zone 2 and is temporarily stored there. Subsequently, wastewater enters from the bottom of the membrane reaction zone 5 through multiple independent inlet branch pipes 24 at the bottom of the inlet zone 2, and is connected to the membrane zone front distributor 28, membrane zone middle distributor 29, and membrane zone rear distributor 30 located at the bottom of the membrane reaction zone 5. This allows for multi-point water distribution within the membrane reaction zone 5, while simultaneously providing multi-point, uniform, and flexible agitation of the sludge in the composite sludge zone 4 at the bottom of the membrane reaction zone 5. The membrane zone front section is the part of the membrane reaction zone 5 closest to the inlet zone 2, while the membrane zone rear section is the part closest to the effluent side.

[0086] ② Turn on the drive motor 19 and adjust the frequency converter 49 via PLC to make the working frequency of the drive motor 19 20~25Hz. The drive motor 19 drives the spiral turntable MABR membrane module 6 to rotate counterclockwise through the reducer 18 and chain 17, with the speed controlled at 2.0~6.0rpm, and maintains a stable rotation.

[0087] At this point, in membrane reaction zone 5, the influent first comes into contact with the sludge in composite sludge zone 4. The lower part of composite sludge zone 4 is mainly composed of anaerobic ammonia oxidation granular sludge, while the middle and upper parts contain flocculent anaerobic ammonia oxidation sludge, heterotrophic denitrifying bacteria, a small amount of facultative heterotrophic bacteria, and aged, detached biofilm. Anaerobic ammonia oxidation bacteria utilize a portion of the ammonia nitrogen in the influent and nitrite nitrogen produced by short-cut nitrification of the MABR biofilm at a ratio of 1:1 to 1:1.32 to produce nitrogen gas and a small amount of nitrate nitrogen, achieving denitrification. The denitrifying bacteria in composite sludge zone 4 utilize a small amount of organic matter in the influent and endogenous organic matter released from dead bacteria as a carbon source to denitrify a small amount of nitrate nitrogen in the mixed liquor into nitrogen gas. These nitrate nitrogen sources include: a small amount of nitrate nitrogen produced by the anaerobic ammonia oxidation reaction and nitrate nitrogen produced by the oxidation of nitrite nitrogen by a small amount of nitrite-oxidizing bacteria (NOB) present in the MABR biofilm.

[0088] During the continuous rotation of the spiral disc MABR membrane module 6, the wastewater layers at different depths in the tank can be stirred and mixed. At the same time, the spiral discs exert an axial pushing effect on the wastewater, which can promote the flow of wastewater in different sections before and after the membrane reaction zone 3, thereby making the wastewater in the membrane reaction zone more uniformly mixed.

[0089] After passing through the composite sludge zone 4, the wastewater makes full contact with the spiral rotating MABR membrane module 6. Dense silica gel membrane filaments 613 are uniformly distributed on the outer surface of the composite membrane element 607, roughly in a radial distribution. During the rotation of the spiral rotating MABR membrane module 6, the MABR membrane filaments 613 make longitudinal, staggered contact with the water, which helps to improve the mass transfer rate of the biofilm on the surface of the MABR membrane filaments 613. The biofilm attached to and growing on the surface of the MABR membrane filaments 613 has a multi-layered composite structure. The inner layer of the biofilm near the MABR membrane filaments 613 is aerobic, mainly containing ammonia-oxidizing bacteria (AOB) and a small amount of nitrite-oxidizing bacteria (NOB); while the outer layer of the biofilm is anoxic or anaerobic, with anaerobic ammonia-oxidizing bacteria as the main microorganisms, and a small amount of heterotrophic denitrifying bacteria also present.

[0090] Ammonia-oxidizing bacteria utilize ammonia nitrogen diffused from wastewater outside the biofilm into the biofilm as a substrate. Under aerobic conditions generated by the molecular introduction of oxygen through the MABR membrane fibers 613, short-cut nitrification occurs, converting ammonia nitrogen into nitrite nitrogen, which then diffuses out of the biofilm driven by the concentration gradient. By controlling the air supply pressure of the membrane module to 10–60 kPa and adjusting the air supply flow rate, 50%–60% of the ammonia nitrogen in the influent is nitrified into nitrite nitrogen through short-cut nitrification.

[0091] Anaerobic ammonia-oxidizing bacteria attached to the outer layer of the MABR biofilm utilize ammonia nitrogen in wastewater and nitrite nitrogen produced by short-cut nitrification in the inner layer of the biofilm for anaerobic ammonia oxidation autotrophic denitrification. The middle layer of the spiral rotating MABR membrane module is a PVC mesh plate, whose rough inner pore surface can be used to attach and grow anaerobic ammonia-oxidizing bacteria, which can also anaerobic ammonia nitrogen in wastewater and nitrite nitrogen produced by short-cut nitrification in the MABR biofilm and diffused into the wastewater for anaerobic ammonia oxidation autotrophic denitrification.

[0092] The continuous rotation of the spiral-rotor MABR membrane module 6 reduces the thickness of the liquid film on the surface of the MABR biofilm, decreases the mass transfer resistance between the matrix and metabolites, and improves the mass transfer efficiency, thereby accelerating the reaction rate of autotrophic denitrification such as short-cut nitrification and anaerobic ammonium oxidation. At the same time, during the continuous rotation of the membrane module, it also helps to release and expel the tiny nitrogen bubbles generated by the autotrophic denitrification reaction on the surface of the biofilm, preventing abnormal detachment caused by the reduced adhesion of the biofilm to the surface of the MABR membrane fibers 613 due to the long stagnation time of the bubbles in the biofilm.

[0093] The continuous rotation of the spiral rotary MABR membrane module 6 ensures complete mixing of wastewater in the upper and middle sections of the membrane reaction zone 3; the lower composite sludge zone 4 has a high-concentration sludge layer that remains loose, resulting in excellent sludge-water contact. This operating mode gives the MABR reactor strong resistance to shock loads.

[0094] ③ After the autotrophic denitrification treatment in the MABR reactor, the ammonia nitrogen removal rate of the wastewater is 90%~95%, and the total nitrogen removal rate is 80%~85%. The effluent is discharged from the effluent pipe 37 at the top of the membrane reaction zone 3.

[0095] Furthermore, in step ①, the multi-point water inlet control method can adopt a conventional uniform water inlet mode, which ensures that the opening degree of each valve on each water inlet branch pipe 24 is consistent, allowing water to enter the bottom of the membrane reaction zone 3 uniformly. At the same time, it can perform multi-point uniform and flexible agitation of the sludge in the composite fouling zone 4, keeping it in a loose state to promote good contact between sludge and water and improve reaction efficiency. Asymmetric water inlet control and / or periodic pulse water inlet control can also be used.

[0096] The asymmetric water inlet control includes: independently adjusting the opening of the inlet valves on each inlet branch pipe 24 to control the flow rate of each inlet branch pipe 24 into the corresponding inlet distributor, forming an asymmetric multi-point water distribution mode, and creating an axial gradient in the wastewater concentration within the membrane reaction zone 3. Preferably, the flow rate of the front distributor 28 of the membrane zone is appropriately increased, and the flow rate of the rear distributor 30 of the membrane zone is reduced, so that the ratio of the inlet flow rates of the three regions (front, middle, and rear) within the membrane reaction zone 3 is 6:3:1 or 5.5:3.5:1, thereby creating an axial gradient in the wastewater concentration within the membrane reaction zone 3. Under the axial pushing action of the spiral surface, a pushing effect is formed between the front and rear regions, which helps to achieve better effluent quality. When the flow rates of the distributors in the front, middle, and rear sections of the membrane zone are adjusted to 6:3:1, a strong stirring effect can be achieved on the sludge at the bottom of the front section of the membrane zone; by alternately increasing the inlet flow rates of the middle and rear sections, strong stirring can be implemented in different zones, thereby maintaining a good sludge morphology in each zone.

[0097] The periodic pulse water inlet control includes: periodically closing the inlet valves on the inlet branch pipe 24 to temporarily store the inlet water in the inlet zone; and when the water level in the inlet zone reaches the pulse water inlet level, sequentially or alternately opening the inlet valves on each inlet branch pipe to generate a pulse water flow using the high water level difference. Specifically, during the normal continuous operation of the spiral rotary MABR membrane module 6, each valve on the inlet branch pipe 24 is periodically closed to temporarily store the inlet water in the inlet zone 2. When the water level in the inlet zone 2 reaches the pulse water inlet level, the PLC controls the opening of the inlet valves 25 (front section), 26 (middle section), and 27 (rear section) of the membrane zone. Under the influence of the high water level difference between the inlet zone 2 and the membrane reaction zone 3, the wastewater flows out of the outlet of the water distributor at the bottom of the membrane reaction zone at a high speed, thereby generating a pulse impact on the bottom of the composite sludge zone 4, loosening the sludge around the water distribution point, and effectively agitating the granular sludge. Periodic pulsed multi-point water inlet agitation provides a combined shearing effect on granular sludge, which helps maintain the long-term stability of granular morphology, thereby enabling the composite sludge zone 4 to perform its various functions and reducing sewage short-circuiting.

[0098] Furthermore, step ② also includes a sludge horizontal plug flow control method based on sludge level feedback: The ultrasonic sludge level gauges at the front and rear ends of the membrane reaction zone 3 monitor the sludge level in the composite sludge zone 4. When the difference between the sludge levels at the front and rear ends exceeds a set threshold, the spiral rotary MABR membrane module 6 is controlled to rotate in reverse to achieve axial reciprocating homogenization of the sludge.

[0099] Specifically, during the rotation of the spiral disc MABR membrane module 6, the spiral disc surface extending into the composite sludge zone 4 will exert a lateral pushing effect on the sludge, which will cause the sludge to move slowly and continuously towards one end of the membrane reaction zone 3. The sludge level in the front and rear sections of the membrane zone is detected by the ultrasonic sludge level gauge 46 in the front section and the ultrasonic sludge level gauge 47 in the rear section of the membrane zone, respectively. When the difference between the two sludge levels exceeds the set limit, the drive motor 19 can be controlled to run in reverse by the PLC controller 50, thereby driving the spiral disc MABR membrane module 6 to rotate in reverse, so that the sludge moves slowly towards the other end of the membrane reaction zone 3.

[0100] By detecting the sludge level difference, the spiral rotary MABR membrane module 6 is automatically switched between forward and reverse rotation, thereby promoting uniform lateral mixing of sludge and improving the activity of the composite sludge zone. Typically, when the spiral rotary MABR membrane module 6 adopts a right-hand spiral arrangement, counterclockwise rotation of the spiral surface generates a thrust towards the front end of the membrane reaction zone (i.e., the influent end); clockwise rotation generates a thrust towards the rear end of the membrane reaction zone (i.e., the effluent end).

[0101] Preferably, the rotation direction of the spiral rotating membrane module 6 is changed every 24 hours to achieve axial reciprocating movement of the sludge in the composite sludge zone 4, maintaining a good loose state of the sludge layer. The timed switching mode, combined with the detection of the sludge level difference between the front and rear sludge zones, forces the adjustment of the rotation direction of the spiral rotating membrane module 6, which can achieve a dynamic balance of the sludge layer in the composite sludge zone and help improve reaction efficiency.

[0102] The present invention provides a second embodiment of the operation method of the above-mentioned spiral rotary MABR autotrophic denitrification reactor.

[0103] After a stable biofilm is formed on the spiral rotating MABR membrane module inside the reactor, the operation mode for biofilm reduction during normal operation is as follows: ① Conventional methods for reducing excessively thick biofilms: When the nitrate nitrogen formation rate reaches 10%~12%, the conventional reduction method is implemented: the rotation speed of the spiral rotary membrane module is gradually increased from 2.0~6.0 rpm to 6.0~18.0 rpm and run for 5~10 minutes.

[0104] Specifically, in a continuously operating rotary MABR reactor, the real-time monitoring values ​​of the influent and effluent water quality obtained by water quality sensors in the influent zone and membrane reaction zone characterize the operating status of the MABR biofilm. When the total nitrogen removal rate of the effluent continuously decreases and the nitrate nitrogen concentration continuously increases, with the nitrate nitrogen formation rate reaching 10%~12%, it initially indicates that the biofilm proliferation on the MABR membrane filaments exceeds the normal value. At this time, a routine reduction operation of the excessively thick biofilm can be performed. The frequency converter 49 is set to 40~50Hz by the PLC controller 50, which increases the speed of the drive motor 19, thereby gradually increasing the rotation speed of the rotary MABR membrane module 6 from the normal operating speed of 2.0~6.0rpm to a high speed level of 6.0~18.0rpm and maintaining it for 5~10 minutes. By increasing the rotation speed of the disc, the hydraulic shear force on the biofilm surface is increased, thus performing a relatively gentle and flexible reduction operation. After the routine reduction is completed, the normal operating speed of the rotary disc is restored. The routine reduction of excessively thick biofilm can also be carried out by timed operation, once every 6 to 8 hours, controlling the rotation speed of the spiral disc at a medium speed of 4.0 to 12.0 rpm, and taking into account the total nitrogen removal and nitrate nitrogen formation, high-speed reduction operation can be carried out as needed.

[0105] ② Methods to enhance the reduction of excessively thick biofilms: During the rotation of the spiral disc MABR membrane module 6 in a fully submerged state, the hydraulic shear force on its surface is mainly due to the viscous friction between the disc and the surrounding water. The biofilm experiences relatively mild stress. Even by increasing the disc rotation speed, the increase in hydraulic shear force is still relatively limited. Moreover, for the inner ring of the spiral disc membrane module, the rotational linear velocity is much lower than that of the outer ring, and the hydraulic shear force it experiences is even smaller. Therefore, the rotation of the spiral disc in the submerged state is only suitable for reducing biofilm thickness under medium thickness conditions and for controlling biofilm thickness in the outer ring area of ​​the disc.

[0106] When the nitrate nitrogen formation rate reaches 13%~15%, the enhanced reduction method is implemented, which includes: S0031: Stop water intake, control the rotation speed of the spiral disc membrane module 6 to 1.0~3.0 rpm, open the downwater valve 39, and lower the water level in the membrane reaction zone 3 to reduce the radial exposure ratio of the spiral disc MABR membrane module 6 to 40%-45%; S0032: Control the spiral rotary MABR membrane module 6 to run at a speed of 1.0-3.0 rpm for 2-3 minutes, and then increase the speed to 2.0-6.0 rpm for 2-3 minutes; S0033: After the enhanced reduction operation is completed, the rotation of the spiral disc MABR membrane module 6 is paused, the dewatering valve 39 is closed, and after the influent is restored to the normal liquid level of the membrane reaction zone 3, the spiral disc MABR membrane module 6 is resumed to run at a speed of 2.0~6.0 rpm.

[0107] Specifically, when the biofilm on the spiral disc MABR membrane module 6 becomes too thick, especially in the inner ring area of ​​the spiral disc, the total nitrogen removal rate of the effluent continuously decreases, the nitrate nitrogen concentration continues to rise, and the nitrate nitrogen generation rate reaches 13%~15%, then enhanced biofilm reduction measures need to be taken.

[0108] The rotation speed of the spiral rotating membrane module 6 is adjusted to 1.0~3.0 rpm and operates continuously; the valves on the inlet branch pipe 24 are closed, including: the inlet valve 25 at the front of the membrane zone, the inlet valve 26 at the middle of the membrane zone, and the inlet valve 27 at the rear of the membrane zone, so that the sewage entering the membrane reaction zone 3 is suspended; the inlet flow rate is reduced to 1 / 2 of the normal operating value, and the sewage is temporarily stored in the inlet zone 2; then the downwater valve 39 is opened, so that the sewage in the upper part of the membrane reaction zone 3 is discharged from the downwater pipe to the sewage equalization tank; the membrane reaction zone 3 After the water level drops, the upper and middle parts of the spiral disc MABR membrane module 6 are exposed above the water surface. The radial exposure ratio of the discs of the membrane module 6 (i.e., the ratio of the height of the air exposed part at the top of the spiral disc to the outer diameter of the disc) is controlled at 40%~45%. Then, the spiral disc membrane module is operated at a speed of 1.0~3.0 rpm for 2~3 minutes, and then the speed is increased to 2.0~6.0 rpm for 2~3 minutes, so that the excessively thick MABR biofilm is reduced under the action of gradually increasing shear force.

[0109] At this time, during the continuous rotation of the semi-submerged spiral rotating membrane module 6, two new sources of shear force are added to its rotating surface. One is the sudden shear force at the water-surface interface. When the disc enters or exits the water surface, the biofilm experiences a sudden change in the water-air medium, and the surface tension and inertial force generate severe local shear stress. The other is the gravity scouring of the water film. After the disc rotates out of the water surface, the surface water film flows downward under the action of gravity, forming a continuous scouring force on the biofilm. The intensity of these two shear forces is relatively large, which can achieve the enhanced reduction of excessively thick proliferating biofilm and sticky biofilm that is difficult to detach.

[0110] After the enhanced reduction of the excessive biofilm is completed, the rotation of the spiral rotating membrane module 6 is paused; the downwater valve 39 is closed; and all valves on the inlet branch pipe 24 are opened to gradually restore the water level in the membrane reaction zone 3 to its normal value. Then, the drive motor 19 is turned on to restore the spiral rotating membrane module 6 to its normal operating condition. At this time, the water level in the membrane reaction zone 3 drops significantly to the biofilm enhanced reduction level, and the water level in the inlet zone is at the pulse inlet level. After the enhanced reduction of the biofilm is completed, the valves on the inlet branch pipe 24 are opened under the control of the PLC. Under the action of the high water level difference formed between the pulse inlet level in the inlet zone 2 and the biofilm enhanced reduction control level in the membrane reaction zone 3, the sewage flows out from the outlet of the distributor at a higher flow rate, thereby more thoroughly pulse-stirring the sludge at the bottom of the composite sludge zone 4, keeping the sludge zone in good condition.

[0111] This invention provides a third embodiment of the operation method of the above-mentioned spiral rotary MABR autotrophic denitrification reactor.

[0112] The control method for distributing membrane attachment on the spiral rotary MABR membrane module includes: S0011, Nitrifying biofilm attachment: ① Inject wastewater and concentrated nitrified sludge mixture into membrane reaction zone 3. The wastewater volume is 75% of the effective volume of membrane reaction zone 3, and the sludge volume is 25% of the effective volume of membrane reaction zone 3. The sludge concentration is 8.0~12.0 g / L. Then let it stand for 30~60 minutes. Next, introduce wastewater into inlet zone 2 through inlet pipe 20. The ammonia nitrogen concentration in the wastewater is the design concentration of the reactor. Open the inlet valve 25 at the front end of the membrane zone, the inlet valve 26 at the middle end of the membrane zone, and the inlet valve 27 at the rear end of the membrane zone. Close the valves of sludge discharge branch pipe 40 and downcomer valve 39, allowing the wastewater to flow by gravity into membrane reaction zone 3 through inlet branch pipe 24. Then, inoculate the concentrated nitrified sludge mixture from the municipal wastewater anoxic tank from the top of membrane reaction zone 3. After the sludge addition is complete, let it stand for 30~60 minutes.

[0113] ② Next, turn on the air supply system, with an aeration pressure of 50~80kPa, an air supply flow rate of 1 / 4~1 / 3 of the design value, and an inlet water flow rate of 1 / 3 of the design value. Control the rotation speed of the spiral disc MABR membrane module to 2.0~3.0rpm. Further, turn on the aeration blower 31 and the inlet and outlet valves, start the rotary motor, and make the spiral disc MABR membrane module 6 rotate counterclockwise at a uniform speed, adjusting the speed to 2.0~3.0rpm and maintaining continuous rotation. Open the valve of the inlet water pipe 20 to continuously supply water at a flow rate of 1 / 3 of the design inlet water volume, and fully open the valves on each inlet branch pipe to ensure uniform water supply to each area of ​​the membrane reaction zone 5.

[0114] ③ The water quality detection sensor in the membrane reaction zone continuously monitors the water quality: When the ammonia nitrogen removal rate reaches 85% or more for the first time, the first stage is considered complete. At this time, the influent flow rate is increased to 2 / 3 of the design value, while the influent concentration remains unchanged; the air supply pressure is kept constant, the air supply flow rate is 1 / 2 to 2 / 3 of the design value, and the rotation speed of the spiral rotary MABR membrane module 6 is increased to 3.0 to 4.0 rpm and kept continuously and stably rotating, entering the second stage of acclimatization; when the ammonia nitrogen removal rate reaches and stabilizes at 85% or more again, the second stage is considered complete. At this point, the influent flow rate and air supply flow rate are increased to the design values, and the influent concentration is the design concentration; the air supply pressure remains unchanged, and the rotation speed of the spiral disc MABR membrane module 6 is 4.0~6.0 rpm; when the ammonia nitrogen removal rate reaches more than 95%, the nitrification biofilm formation process is completed; at this point, the rotation of the spiral disc membrane module 6 can be stopped, and after the sewage in the membrane reaction zone 3 is allowed to stand for 30 minutes, the drain valve 39 is opened to discharge the sewage in the upper part of the membrane reaction zone 3, so that 20%~30% of the spiral disc MABR membrane module 6 is exposed above the water surface, and the apparent morphology of the biofilm on the surface of the MABR membrane filaments is observed and recorded.

[0115] S0012, Short-range nitrification biofilm conversion stage: Maintaining the operating parameters at the end of the nitrification biofilm formation process, the spiral disc MABR membrane module 6 rotates continuously, with continuous influent and effluent in membrane reaction zone 3. The aeration pressure is adjusted to 20-40 kPa, and the air supply flow rate is gradually reduced, causing the ammonia nitrogen removal rate in the water stored in membrane reaction zone 3 to decrease to 50%-60%, while the nitrite rate gradually increases and stabilizes at 70%-80%, leading to the gradual accumulation of nitrite in the membrane reaction zone. Then, the aeration method is adjusted to intermittent aeration, with aeration stopped for 15 minutes after 30 minutes. The rotation speed of the spiral disc MABR membrane module 6 remains unchanged, and the process continues for a period of time until the nitrite rate reaches over 90%, completing the short-cut nitrification biofilm conversion stage. At this point, by reducing the air supply and pressure of the composite membrane element 607 and implementing intermittent aeration, the activity of nitrite-oxidizing bacteria (NOB) in the biofilm is effectively inhibited, while ammonia-oxidizing bacteria (AOB) are less affected, thus gradually transforming the MABR biofilm from a nitrification biofilm into a short-cut nitrification biofilm.

[0116] S0013, Anaerobic ammonia oxidation biofilm formation stage: Stop the water intake and aeration, stop the rotation of the spiral disc MABR membrane module 6, and let the wastewater in the membrane reaction zone 3 stand for 60 minutes. Then, open the bottom valve of the sludge discharge branch pipe 40 to discharge all the nitrified sludge. Discharge the sludge until 20% to 30% of the height of the spiral disc MABR membrane module 6 is exposed above the water surface. Observe and record the morphology of the biofilm on the membrane filament surface.

[0117] Subsequently, the sludge discharge valve was closed, and anaerobic ammonia oxidation sludge was inoculated into membrane reaction zone 3 at a rate of 15%–20% of the effective volume of membrane reaction zone 3. The volume ratio of particulate to suspended anaerobic ammonia oxidation sludge in the inoculated sludge was 7:1–8:1. After inoculation, the influent was turned on at the design flow rate. After the wastewater submerged the spiral rotary MABR membrane module 6, the drive motor 19 was turned on, causing the spiral rotary MABR membrane module 6 to rotate continuously counterclockwise at a speed of 2.0–6.0 rpm. The aeration rate was set at the final value of the short-cut nitrification biofilm conversion stage, and the aeration pressure was 20–40 kPa. Intermittent aeration was adopted, i.e., aeration was stopped for 15 minutes after aeration for 30–60 minutes. The MABR reactor operated continuously, allowing suspended anaerobic ammonia oxidation bacteria to attach and grow on the surface of the MABR short-cut nitrification biofilm, gradually forming a composite biofilm with ammonia oxidation bacteria as the main component in the inner layer and anaerobic ammonia oxidation bacteria as the main component in the outer layer. During reactor operation, the influent and effluent water quality is monitored in real time by water quality sensors in the influent and membrane reaction zone. When the ammonia nitrogen removal rate reaches 90% and the total nitrogen removal rate reaches over 80%, the anaerobic ammonia oxidation biofilm formation stage is completed. Subsequently, the influent and the rotation of the spiral disc can be paused, and by opening the downwater valve 39, 20% to 30% of the spiral disc MABR membrane module 6 is exposed above the water surface to observe and record the morphology of the biofilm on the membrane filaments.

[0118] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0119] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. 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 spiral rotating disc type MABR autotrophic denitrification reactor, comprising: The reaction tank (1) has an internal space divided into an inlet zone (2) and a membrane reaction zone (3), and the bottom of the membrane reaction zone (3) has a composite sludge zone (4). The spiral rotary MABR membrane module (6) is horizontally arranged in the membrane reaction zone (3) and can rotate around its axis under the action of the driving device. The spiral rotary MABR membrane module (6) is composed of multiple sets of composite membrane elements (607) and a spiral rotary frame (601) forming an equal pitch spiral surface structure. The arrangement density of the MABR membrane filaments (613) of the composite membrane element (607) is higher on the outer ring than on the inner ring. A double-layer hollow rotating shaft (7) is horizontally arranged in the membrane reaction zone (3). The inner ring of the spiral rotating MABR membrane module (6) is connected to the outer peripheral wall of the double-layer hollow rotating shaft (7). The inner pipe of the double-layer hollow rotating shaft (7) is the air inlet zone (9) connected to the gas supply system, and the outer annular area is the exhaust zone (8). The membrane fiber air inlet end (609) of the composite membrane element (607) is connected to the air inlet zone (9), and the membrane fiber exhaust end (611) is connected to the exhaust zone (8).

2. The spiral rotary MABR autotrophic denitrification reactor according to claim 1, characterized in that, The spiral turntable frame (601) includes an inner ring support and an outer ring support in the shape of a helix with equal pitch. The inner ring support and the outer ring support are connected by a radial support rod perpendicular to the helical axis. The composite membrane element (607) is a fan-shaped ring with a helical surface, and multiple composite membrane elements (607) are detachably fixed between the inner ring support and the outer ring support to form a complete equidistant helical surface.

3. The spiral rotary MABR autotrophic denitrification reactor according to claim 1, characterized in that, The composite membrane element (607) includes a membrane element frame (608), a membrane element grid plate (612), and MABR membrane fibers (613). The MABR membrane fibers (613) are symmetrically distributed on the outer surface of the membrane element grid plate (612) from the center line of the spiral surface to both straight edges. The end of the MABR membrane fiber (613) near the center line of the spiral surface of the membrane element grid plate (612) is the membrane fiber inlet end (609), and the end near both straight edges of the membrane element grid plate (612) is the membrane fiber exhaust end (611).

4. The spiral rotary MABR autotrophic denitrification reactor according to claim 1, characterized in that, The driving device includes a drive motor (19) and a reducer (18) located on the top of the reaction tank (1). A driven gear is provided on the double-layer hollow rotating shaft (7). The driving gear on the reducer (18) is connected to the driven gear through a chain (17).

5. The spiral rotary MABR autotrophic denitrification reactor according to claim 1, characterized in that, The double-layer hollow rotating shaft (7) is composed of inner tubes and outer tubes of different diameters nested together. The diameter ratio of the inner tube and the outer tube is 1.4:1 to 1.6:

1. The front end of the inner tube extends out of the front end of the outer tube and is connected to the air inlet pipe (32) of the air supply system through the air inlet end rotary joint (11). The rear end of the inner tube is closed and maintains a 1 / 2 shaft diameter distance from the rear end of the outer tube. The rear end of the outer tube is connected to the exhaust pipe (35) through the exhaust end rotary joint (14).

6. The spiral rotary MABR autotrophic denitrification reactor according to claim 1, characterized in that, The water inlet zone (2) is located at one end of the long side of the membrane reaction zone (3), and its bottom is located at the middle of the height of the membrane reaction zone (3). The bottom of the water inlet zone (2) is provided with multiple water inlet branch pipes (24), and the bottom of the membrane reaction zone (3) is provided with multiple sets of water inlet distributors arranged along the length of the membrane reaction zone (3). The water inlet branch pipes (24) are respectively connected to the corresponding water inlet distributors, and each water inlet branch pipe (24) is provided with a water inlet valve. The membrane reaction zone (3) is also equipped with a downwater pipe (38) and an outlet pipe (37). The downwater pipe (38) is equipped with a downwater valve (39) to control the liquid level in the membrane reaction zone (3).

7. The spiral rotary MABR autotrophic denitrification reactor according to claim 1, characterized in that, The lower rear end of the membrane reaction zone (3) is provided with multiple sludge discharge branch pipes (40) of different heights, and the front and rear ends of the membrane reaction zone (3) are respectively provided with ultrasonic sludge level gauges. Both the water inlet zone (2) and the membrane reaction zone (3) are equipped with level gauges and water quality detection sensors. The water quality parameters include at least one of the following: pH value, temperature, ammonia nitrogen concentration, dissolved oxygen, oxidation-reduction potential, nitrite nitrogen, and nitrate nitrogen.

8. A method for operating control of a reactor based on any one of claims 1 to 7, characterized in that, Includes the following steps: S001: Start the reactor and form a biofilm on the spiral rotating MABR membrane module (6) by stepwise membrane attachment; S002: Close the sludge discharge branch pipe (40) and the dewatering valve (39), continuously inject ammonia-containing wastewater into the membrane reaction zone (3), and supply air to the spiral rotary MABR membrane module (6) through the air supply system, control the spiral rotary MABR membrane module (6) to rotate continuously at the first speed, and carry out autotrophic denitrification treatment; S003: Obtain water quality test data of the membrane reaction zone (3). When the water quality test data indicates that the thickness of the MABR biofilm exceeds the normal range, perform biofilm reduction operation. The biofilm reduction operation includes conventional reduction methods and enhanced reduction methods; The conventional reduction method includes: controlling the spiral rotary MABR membrane module (6) to operate at a second speed higher than the first speed, and performing conventional reduction by enhancing the hydraulic shear force; The enhanced reduction method includes: lowering the liquid level in the membrane reaction zone (3), controlling the radial exposure ratio of the spiral rotating MABR membrane module (6), and using the sudden shear force at the gas-liquid interface and the gravity of the water film to flush away and peel off the excessively thick biofilm. S004: After the biofilm reduction operation is completed, resume normal operation.

9. The reactor operation control method according to claim 8, characterized in that, In step S003: When the nitrate nitrogen formation rate reaches 10%~12%, the conventional reduction method is implemented: the rotation speed of the spiral rotary MABR membrane module (6) is gradually increased from 2.0~6.0 rpm to 6.0~18.0 rpm and run for 5~10 minutes; When the nitrate nitrogen formation rate reaches 13%~15%, the enhanced reduction method is implemented, which includes: S0031: Stop water intake, control the rotation speed of the spiral disc MABR membrane module (6) to 1.0~3.0 rpm, open the downwater valve (39), and lower the water level in the membrane reaction zone (3) to reduce the radial exposure ratio of the spiral disc MABR membrane module (6) to 40%-45%; S0032: Control the spiral rotary MABR membrane module (6) to run at a speed of 1.0-3.0 rpm for 2-3 minutes, and then increase the speed to 2.0-6.0 rpm for 2-3 minutes; S0033: After the enhanced reduction operation is completed, the rotation of the spiral disc MABR membrane module (6) is paused, the water discharge valve (39) is closed, and after the water inlet is restored to the normal liquid level of the membrane reaction zone (3), the spiral disc MABR membrane module (6) is restored to a speed of 2.0~6.0 rpm.

10. The reactor operation control method according to claim 8, characterized in that, It also includes a multi-point water inlet control mode, which includes asymmetric water inlet control and / or periodic pulse water inlet control; The asymmetric water inlet control includes: independently adjusting the opening of the water inlet valve on each water inlet branch pipe (24), controlling the flow rate of each water inlet branch pipe (24) into the corresponding water inlet distributor, forming an asymmetric multi-point water distribution mode, and forming an axial gradient of sewage concentration in the membrane reaction zone (3); The periodic pulse water inlet control includes: periodically closing the water inlet valve on the water inlet branch pipe (24) so ​​that the water inlet is temporarily stored in the water inlet area (2). When the water level in the water inlet area (2) reaches the pulse water inlet level, the water inlet valve on each water inlet branch pipe (24) is opened sequentially or alternately to generate pulse water flow by utilizing the high water level difference.

11. The reactor operation control method according to claim 8, characterized in that, It also includes a sludge horizontal plug flow control method based on sludge level feedback: According to the ultrasonic sludge level gauges at the front and rear ends of the membrane reaction zone (3), the sludge level of the composite sludge zone (4) in the membrane reaction zone (3) is monitored. When the difference between the sludge levels at the front and rear ends exceeds the set threshold, the spiral turntable MABR membrane module (6) is controlled to rotate in reverse to achieve axial reciprocating homogenization of the sludge.

12. The reactor operation control method according to claim 8, characterized in that, It also includes biofilm attachment methods, including: S0011, Nitrifying biofilm attachment: Wastewater and concentrated nitrified sludge mixture were injected into the membrane reaction zone (3). The wastewater volume was 75% of the effective volume of the membrane reaction zone (3), the sludge volume was 25% of the effective volume of the membrane reaction zone (3), and the sludge concentration was 8.0~12.0 g / L. After that, the mixture was allowed to stand for 30~60 min. Turn on the air supply system, with an aeration pressure of 50~80kPa, an air supply flow rate of 1 / 4~1 / 3 of the design value, an influent flow rate of 1 / 3 of the design value, and control the rotation speed of the spiral rotary MABR membrane module (6) to 2.0~3.0rpm; The water quality detection sensor in the membrane reaction zone (3) continuously monitors the following: when the ammonia nitrogen removal rate reaches 85% or more for the first time, the influent flow rate is increased to 2 / 3 of the design value, the air supply flow rate is increased to 1 / 2 to 2 / 3 of the design value, and the rotation speed of the spiral disc MABR membrane module (6) is 3.0 to 4.0 rpm; when the ammonia nitrogen removal rate reaches and stabilizes at 85% or more again, the influent flow rate and air supply flow rate are increased to the design value, and the rotation speed of the spiral disc MABR membrane module (6) is 4.0 to 6.0 rpm; when the ammonia nitrogen removal rate reaches 95% or more, the nitrification biofilm attachment process is completed. S0012, Short-cut nitrification biofilm conversion stage: The aeration pressure is adjusted to 20~40kPa, and the air supply flow rate is gradually reduced, so that the ammonia nitrogen removal rate of the water stored in the membrane reaction zone (3) is reduced to 50%~60%, and the nitrification rate gradually increases and stabilizes at 70%~80%; then the aeration mode is adjusted to intermittent aeration until the nitrification rate reaches more than 90%, and the short-cut nitrification biofilm conversion stage is completed. S0013, Anaerobic ammonia oxidation biofilm formation stage: Stop water intake and aeration, stop the rotation of the spiral disc MABR membrane module (6), and discharge the nitrified sludge; Anaerobic ammonia oxidation sludge is inoculated into the membrane reaction zone (3) at a rate of 15% to 20% of the effective volume of the membrane reaction zone (3). After inoculation, the influent flow rate is turned on to the design value, and the spiral rotary MABR membrane module (6) is rotated at a speed of 2.0 to 6.0 rpm. The aeration rate is the final value of the short-cut nitrification biofilm conversion stage, and the aeration pressure is 20 to 40 kPa. Intermittent aeration mode is adopted. When the ammonia nitrogen removal rate reaches 90% and the total nitrogen removal rate reaches more than 80%, the anaerobic ammonia oxidation biofilm attachment stage is completed.

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