Energy-saving oxygen granular sludge sewage treatment system and method

Abstract

The invention discloses an energy-saving aerobic granular sludge sewage treatment system and method, and relates to the technical field of sewage treatment, the energy-saving aerobic granular sludge sewage treatment system comprises a wind-solar complementary energy supply module, an aerobic granular sludge module and an assembly type structure module; the aerobic granular sludge sewage treatment module comprises a grating tank, biological reaction tanks, a self-lifting stirrer, an aeration pump and a PLC cabinet, the plurality of biological reaction tanks are connected in parallel and then are connected with the grating tank, the self-lifting stirrer is arranged in each biological reaction tank, the biological reaction tanks are connected with the aeration pump, and the PLC cabinet is connected with the PLC cabinet. And the PLC cabinet is connected with the self-lifting stirrer, the aeration pump and the wind-solar complementary energy supply module. The biological reaction tank runs in an anaerobic / aerobic / anoxic mode, sewage between the reactors flows automatically by gravity, the occupied area and the site construction period can be greatly reduced by adopting an assembly type construction mode, the sewage treatment efficiency is high, the yield of residual sludge is low, no external carbon source is added, no pump flows automatically, no backflow is caused, the operation and maintenance are simple, and the cost is low. The economic benefit and the carbon emission reduction effect are obvious.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to an energy-saving oxygen granular sludge sewage treatment system and method. Background Art

[0002] The wastewater treatment industry, a cornerstone of modern society, is also a critical energy-intensive sector. Currently, decentralized wastewater treatment faces numerous challenges. Specifically, decentralized wastewater is characterized by large volumes that are difficult to centralize, and high water quality fluctuations. This requires higher chemical and energy consumption, increasing costs and hindering widespread adoption. Currently used wastewater treatment technologies often suffer from large land occupation requirements, high capital costs, long construction cycles, and difficult operation and maintenance. The development of efficient, low-carbon decentralized wastewater treatment technologies is urgently needed.

[0003] Biological treatment is the most widely used and economical wastewater treatment technology. Aerobic granular sludge offers advantages such as compact structure, good settling performance, high biomass, diverse biodiversity, high sludge activity, and strong resistance to shock loads. However, rapid cultivation and long-term stable operation of aerobic granular sludge are challenging. Therefore, an energy-saving aerobic granular sludge wastewater treatment system and method are proposed to address these challenges. Summary of the Invention

[0004] The purpose of this application is to provide an energy-saving aerobic granular sludge sewage treatment system and method to solve the problems raised in the above background technology.

[0005] To achieve the above objectives, the present application provides the following technical solution: an energy-saving aerobic granular sludge sewage treatment system, comprising:

[0006] Wind and solar complementary energy supply module;

[0007] Aerobic granular sludge sewage treatment module, which includes a grille tank, several biological reaction tanks, several self-lifting agitators, an aeration pump, and a PLC cabinet. Several biological reaction tanks are connected to the grille tank in parallel. Several biological reaction tanks are equipped with self-lifting agitators, and several biological reaction tanks are connected to the aeration pump. The PLC cabinet is connected to the self-lifting agitator, aeration pump, and wind-solar complementary energy supply module.

[0008] The assembled structural module includes a box body, a wind-solar complementary energy supply module is installed on the top of the box body, and the grid pool and the biological reaction pool are both built into the inside of the box body.

[0009] As a further supplement to this solution, the wind-solar complementary energy supply module includes a wind turbine, a solar power generation device, a wind-solar complementary controller, a battery and an inverter. The output end of the wind turbine is connected to the wind-solar complementary controller, the output end of the solar power generation device is connected to the wind-solar complementary controller, the wind-solar complementary controller is connected to the battery, the battery is connected to the inverter, and the PLC cabinet is connected to the inverter.

[0010] As a further supplement to this solution, the biological reaction tank is a sequencing batch reactor with a height-to-diameter ratio of 1.5-3. Each sequencing batch reactor is provided with a water inlet pipe, a water outlet pipe and an aeration device.

[0011] As a further supplement to this solution, a partition, a vent cap and an inspection ladder are also installed on the inside of the box, and a manhole is provided at the top of the box at a position corresponding to the inspection ladder.

[0012] As a further supplement to this solution, the self-lifting agitator includes a drive motor, a stirring frame, a limiting shaft, a clutch assembly, a return spring and a conical limiting cylinder;

[0013] The driving motor is fixed to the inner top of the sequencing batch reactor through a mounting frame, the limiting shaft is coaxially fixed to the output end of the driving motor, the stirring frame is vertically slidably sleeved on the outer side of the limiting shaft, and the top of the stirring frame is fixed to the conical limiting cylinder through a connecting frame;

[0014] The inner diameter of the conical limiting cylinder gradually decreases from top to bottom, and when the drive motor is in a non-operating state, the clutch assembly is located at the bottom of the conical limiting cylinder;

[0015] The clutch assembly is fixed on the limiting shaft rod, and the clutch assembly is located on the inner side of the conical limiting cylinder. The return spring is fixed between the clutch assembly and the connecting frame.

[0016] As a further supplement to this solution, the stirring frame includes a limiting sleeve and several stirring rods. The limiting sleeve is vertically slidably sleeved on the outside of the limiting shaft, and the inner side of the limiting sleeve is a non-cylindrical cavity. The limiting sleeve is fixed to the connecting frame, and several stirring rods are equidistantly fixed on the side end of the limiting sleeve from top to bottom.

[0017] As a further supplement to this solution, a rotating blade is coaxially fixed to the bottom end of the limiting sleeve, and a flexible protective sleeve is provided on the outer side of the return spring, and the flexible protective sleeve is fixed between the connecting frame and the clutch assembly.

[0018] As a further supplement to this solution, the clutch assembly includes a fixed sleeve and a counterweight slider. The fixed sleeve is horizontally fixed to the side end of the limiting shaft rod, the counterweight slider is horizontally slidably sleeved on the inner side of the fixed sleeve, and the end of the counterweight slider away from the limiting shaft rod passes through the fixed sleeve. The counterweight slider is equidistantly installed with several balls on the side end along its sliding direction.

[0019] The sewage treatment method based on the above energy-saving oxygen granular sludge sewage treatment system includes the following steps:

[0020] Step 1: The sewage passes through the grid pool and enters the biological reaction pool;

[0021] Step 2: Maintain the bioreactor in an anaerobic environment and stir the bioreactor using a self-lifting stirrer to maintain the reaction for a first preset time;

[0022] Step 3: Turn on the aeration pump to keep the biological reaction tank in an aerobic environment and stir it, so that the reaction continues for a second preset time;

[0023] Step 4: Turn off the aeration pump, keep the biological reaction tank in an anoxic environment and stir it, and keep the reaction for a third preset time;

[0024] Step 5: Turn off the self-lifting agitator to allow the mixture in the bioreactor to settle for a fourth preset time;

[0025] Step 6: The supernatant obtained by settling is discharged according to the set ratio, and the remaining sludge and clear liquid remain in the biological reaction tank;

[0026] Step 7: Repeat steps 1 to 6, shortening the fourth preset time each time, until aerobic granular sludge is formed in the bioreactor;

[0027] Step 8: Keep the fourth preset time for aerobic granular sludge formation unchanged and repeat steps 1 to 6.

[0028] As a further supplement to this solution, the first preset time duration is 1-3 hours, the second preset time duration is 0.5-2 hours, the third preset time duration is 1-3 hours, and the fourth preset time duration is 0.1-0.5 hours;

[0029] The discharge ratio of the supernatant in step 6 is 20-80% of the total volume.

[0030] In summary, the technical effects and advantages of the present invention are as follows:

[0031] 1. The aerobic granular sludge used in the present invention has a fast settling speed, does not require a secondary sedimentation tank, and has no backflow. By selecting reasonable parameters, the use of aerobic granular sludge in decentralized sewage treatment has more advantages than traditional technologies, and realizes gravity flow of sewage, does not require lifting pumps and complex pipelines, and has a low failure rate; the output of residual sludge is reduced by more than 80%, the maintenance frequency is low, and the operation is simple; no external carbon source and phosphorus removal agent are required, and the effluent stability is better than the urban and rural domestic sewage discharge standards; and the use of PLC and monitoring equipment can realize online monitoring and remote control, and the operation is flexible.

[0032] 2. In the present invention, the aerobic granular sludge treatment process has a short carbon footprint, low sludge yield, no lifting, and low aeration energy consumption. It uses renewable energy to achieve energy self-sufficiency, and the surplus electricity can be provided to surrounding residents. In addition, the wind and solar complementarity can better meet the continuous electricity demand of the sewage treatment system, reducing total energy consumption and carbon emissions by 30-60%, with significant energy-saving effects. In addition, the prefabricated components have a compact structure, and the system can save 40-75% of the floor space. The prefabricated assembly site has a short construction period, less construction waste, and is convenient to build and transport.

[0033] 3. In the present invention, through the coordinated arrangement of the drive motor, the stirring frame, the limiting shaft, the clutch assembly, the return spring and the conical limiting cylinder, when the drive motor is operating, the counterweight slider slides outward under the action of centrifugal force, and the counteraction between the counterweight slider and the conical limiting cylinder is utilized to cause the conical limiting cylinder to move the stirring frame downward into the bioreactor, and the stirring frame rotates along with the limiting shaft to stir the sewage in the bioreactor; when the drive motor stops, the return spring moves the stirring frame upward and resets it, which will not affect the sedimentation of the sludge and the subsequent discharge operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a structural framework diagram of the wind-solar hybrid energy supply system in this embodiment;

[0036] Figure 2 This is a flow chart of the aerobic granular sludge sewage treatment system in this embodiment;

[0037] Figure 3 The inlet and outlet water concentrations and removal rates of ammonia nitrogen, total inorganic nitrogen, total phosphorus, and chemical oxygen demand in this embodiment are shown;

[0038] Figure 4 This is a schematic diagram of the overall three-dimensional structure of the self-lifting agitator in this embodiment in a stopped state;

[0039] Figure 5 This is a schematic diagram of the overall three-dimensional structure of the self-lifting agitator in this embodiment in the operating state;

[0040] Figure 6 Schematic diagram of the cross-sectional structure of the self-lifting agitator in this embodiment;

[0041] Figure 7 Schematic diagram of the disassembled structure of the self-lifting agitator in this embodiment.

[0042] In the figure: 1. Mounting frame; 2. Driving motor; 3. Stirring frame; 31. Limiting sleeve; 32. Stirring rod; 4. Limiting shaft; 5. Clutch assembly; 51. Fixed sleeve; 52. Counterweight slider; 53. Ball; 6. Return spring; 7. Connecting frame; 8. Rotating blade; 9. Conical limiting cylinder; 10. Flexible protective cover. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] Example: Reference Figure 1-2 An energy-saving oxygen granular sludge sewage treatment system shown includes a wind-solar complementary energy supply module, an aerobic granular sludge sewage treatment module and an assembled structure module.

[0045] Among them, Figure 1 It is shown that the wind-solar complementary energy supply module includes a wind turbine, a solar power generation device, a wind-solar complementary controller, a battery and an inverter. The output end of the wind turbine is connected to the wind-solar complementary controller, the output end of the solar power generation device is connected to the wind-solar complementary controller, the wind-solar complementary controller is connected to the battery, and the battery is connected to the inverter. The loads in the figure include the PLC cabinet and the electrical equipment of the surrounding residents. Renewable energy (solar energy and wind energy) is used to achieve energy self-sufficiency, and the surplus electricity can be provided to the surrounding residents, reducing the total energy consumption and carbon emissions by 30%-60%.

[0046] Among them, the aerobic granular sludge sewage treatment module includes a screen tank, several biological reaction tanks, several self-lifting agitators, an aeration pump and a PLC cabinet. Several biological reaction tanks are arranged in parallel and connected to the screen tank. Several biological reaction tanks are equipped with self-lifting agitators, and several biological reaction tanks are connected to the aeration pump. The PLC cabinet is connected to the self-lifting agitator, the aeration pump, and the inverter of the wind-solar complementary energy supply module.

[0047] Specifically, the biological reaction tank is a sequencing batch reactor with a height-to-diameter ratio of 1.5-3. Each sequencing batch reactor is provided with an inlet pipe, an outlet pipe and an aeration device. The aeration device is a conventional aeration pipe connected to an aeration pump.

[0048] Among them, the prefabricated structural module includes a box body, the wind-solar complementary energy supply module is installed on the top of the box body, the grille pool and the biological reaction tank are both built into the inside of the box body. In addition, conventional partitions, ventilation caps and maintenance ladders are also installed on the inside of the box body, and a manhole is set at the position corresponding to the maintenance ladder on the top of the box body to facilitate maintenance personnel to enter for maintenance.

[0049] The sewage treatment method based on the above energy-saving oxygen granular sludge sewage treatment system includes the following steps:

[0050] Step 1: The sewage passes through the grid pool and enters the biological reaction pool;

[0051] Step 2: Maintain the bioreactor in an anaerobic environment and stir the bioreactor using a self-lifting stirrer to maintain the reaction for a first preset time;

[0052] Step 3: Turn on the aeration pump to keep the biological reaction tank in an aerobic environment and stir it, so that the reaction continues for a second preset time;

[0053] Step 4: Turn off the aeration pump, keep the biological reaction tank in an anoxic environment and stir it, and keep the reaction for a third preset time;

[0054] Step 5: Turn off the self-lifting agitator to allow the mixture in the bioreactor to settle for a fourth preset time;

[0055] Step 6: The supernatant obtained by settling is discharged according to the set ratio, and the remaining sludge and clear liquid remain in the biological reaction tank;

[0056] Step 7: Repeat steps 1 to 6, shortening the fourth preset time each time, until aerobic granular sludge is formed in the bioreactor;

[0057] Step 8: Keep the fourth preset time for aerobic granular sludge formation unchanged and repeat steps 1 to 6.

[0058] As a further supplement to this solution, the first preset time duration is 1-3 hours, the second preset time duration is 0.5-2 hours, the third preset time duration is 1-3 hours, and the fourth preset time duration is 0.1-0.5 hours;

[0059] The discharge ratio of the supernatant in step 6 is 20-80% of the total volume.

[0060] Using the above sewage treatment system and the above sewage treatment method, the mud cake obtained from the dewatering workshop of the sewage treatment plant was dissolved and passed through a 2mm sieve for experiments. In the initial state, the sludge concentration was about 4000mg / L;

[0061] like Figure 2It is shown that the system operation mode is anaerobic / aerobic / anoxic (A / O / A) mode, and the anoxic section is placed at the end, which is conducive to the enrichment of denitrifying polyphosphate bacteria. The anaerobic section converts the external carbon source into an intracellular carbon source, and the anoxic section uses the internal carbon source for denitrification and phosphorus removal, saving the amount of carbon source added and realizing synchronous denitrification and phosphorus removal; the operating conditions are anaerobic section 120min, aerobic section 120min, anoxic section 120min (including sedimentation 0.1-1h, effluent 3min, and influent 2min), each cycle is 6h, and 4 cycles per day.

[0062] The outlet is set at the middle height of the bioreactor, the water output per cycle accounts for 50% of the total reactor volume, the hydraulic retention time is 12h, and the inlet adopts low-load artificial water distribution and enters from the top of the bioreactor. Its composition is 230mg / LCOD, 3.5mg / L TP, 22mg / L NH4+-N, 10mg / L CaCl2, 10mg / L MgSO4·7H2O, 0.9mg / L FeCl3·6H2O, 0.15mg / L H3BO3, 0.18mg / L KI, 0.03mg / L CuSO4·5H2O, 0.06mg / L MnCl2·4H2O, 0.12mg / LZnSO4·7H2O, 0.15mg / L CoCl2·6H2O, 0.06mg / L Na2MoO4·2H2O and 10mg / L EDTA; the stirring speed is 150rpm.

[0063] Under this operating mode, the phosphate-accumulating bacteria in the bioreactor complete carbon source absorption during the anaerobic phase, converting extracellular carbon sources into intracellular carbon sources while simultaneously releasing phosphorus. During the aerobic phase, aeration is controlled at 200 mL / min by a gas flowmeter, and the dissolved oxygen concentration is maintained at 3-4 mg / L. During this phase, ammonia nitrogen is removed through nitrification and simultaneous nitrification and denitrification. Simultaneously, the phosphate-accumulating bacteria utilize stored glycogen within their cells as energy to absorb excess phosphorus from the water environment. During the anoxic phase, when the dissolved oxygen concentration is less than 0.5 mg / L, the microorganisms in the bioreactor further achieve denitrification and phosphorus removal, achieving effluent quality that meets the Class A standard of GB18918-2002, "Pollutant Discharge Standard for Municipal Wastewater Treatment Plants." Over the entire operating cycle, sludge concentration increased from an initial 4552 mg / L to 7785 mg / L, with a sludge yield of 0.38 gMLSS / gCOD.

[0064] Compared to existing technologies, the aerobic granular sludge used in this solution features rapid settling, eliminates the need for a secondary sedimentation tank, and eliminates backflow. By selecting appropriate parameters, the use of aerobic granular sludge in decentralized wastewater treatment offers significant advantages over traditional technologies. The compact prefabricated components reduce system floor space by 40-75%. This sewage treatment system utilizes gravity flow, eliminating the need for lift pumps and complex piping, resulting in a low failure rate. Residual sludge production is reduced by over 80%, with low maintenance and simple operation. No external carbon source or phosphorus removal agents are required, and the effluent is stable, exceeding urban and rural domestic sewage discharge standards. The use of a PLC and monitoring equipment enables online monitoring and remote control, ensuring flexible operation. The aerobic granular sludge treatment process has a short carbon footprint, low sludge yield, no lifting required, and low aeration energy consumption, resulting in significant energy savings. Furthermore, the prefabricated system features a short on-site construction period, minimal construction waste, and convenient construction and transportation. The system utilizes renewable energy for energy self-sufficiency, with surplus electricity available to surrounding residents, reducing total energy consumption and carbon emissions by 30-60%. Furthermore, the complementary wind and solar power systems can better meet the continuous power needs of the sewage treatment system.

[0065] Regarding the above self-lifting agitator, specifically, Figure 4-7 It is shown that the self-lifting agitator includes a driving motor 2, a stirring frame 3, a limiting shaft 4, a clutch assembly 5, a reset spring 6 and a conical limiting cylinder 9. The driving motor 2 is fixed to the inner top of the sequencing batch reactor through the mounting frame 1. The limiting shaft 4 is coaxially fixed with the output end of the driving motor 2. The stirring frame 3 is vertically slidably sleeved on the outer side of the limiting shaft 4, and the top of the stirring frame 3 is fixed to the conical limiting cylinder 9 through the connecting frame 7. The inner diameter of the conical limiting cylinder 9 gradually decreases from top to bottom, and the driving motor 2 is in a non-operating state. The clutch assembly 5 is located at the bottom position of the conical limiting cylinder 9, the clutch assembly 5 is fixed on the limiting shaft 4, and the clutch assembly 5 is located on the inner side of the conical limiting cylinder 9. The reset spring 6 is fixed between the clutch assembly 5 and the connecting frame 7, and is used to move the stirring frame 3 upward and reset when the driving motor 2 stops.

[0066] Regarding the stirring frame 3, specifically, the stirring frame 3 includes a limiting sleeve 31 and several stirring rods 32. The limiting sleeve 31 is vertically slidably sleeved on the outside of the limiting shaft 4, and the inner side of the limiting sleeve 31 is a non-cylindrical cavity. The limiting sleeve 31 is fixed to the connecting frame 7, and several stirring rods 32 are equidistantly fixed to the side ends of the limiting sleeve 31 from top to bottom.

[0067] In order to further improve the stirring effect and reduce the sedimentation at the bottom of the pool, a lifting blade 8 is coaxially fixed to the bottom end of the limiting sleeve 31, and a flexible protective sleeve 10 is provided on the outer side of the reset spring 6. The flexible protective sleeve 10 is fixed between the connecting frame 7 and the clutch assembly 5, which can effectively protect the reset spring 6, wherein the reset spring 6 is a conventional tension spring.

[0068] Regarding the clutch assembly 5, specifically, the clutch assembly 5 includes a fixed sleeve 51 and a counterweight slider 52. The fixed sleeve 51 is horizontally fixed to the side end of the limiting shaft 4, and the counterweight slider 52 is horizontally slidably sleeved on the inner side of the fixed sleeve 51, and the end of the counterweight slider 52 away from the limiting shaft 4 passes through the fixed sleeve 51. The counterweight slider 52 is equidistantly installed with a number of balls 53 on the side ends along its sliding direction. The balls 53 are used to reduce the friction force during the sliding process of the counterweight slider 52.

[0069] Based on the coordinated arrangement of the above structure, when the driving motor 2 is in a non-operating state, the clutch assembly 5 is located at the bottom position of the conical limiting cylinder 9. At this time, the stirring frame 3 is stably located on the upper side of the biological reaction tank under the action of the return spring 6; when the driving motor 2 is operating, the counterweight slider 52 slides outward under the action of centrifugal force, and the counterweight slider 52 and the conical limiting cylinder 9 are used to offset the conical limiting cylinder 9 to move the stirring frame 3 down into the biological reaction tank, and the stirring frame 3 rotates with the limiting shaft 4 to stir the sewage in the biological reaction tank; when the driving motor 2 stops, the return spring 6 moves the stirring frame 3 upward and resets it, which will not affect the sedimentation of the sludge and the subsequent discharge operation.

[0070] Finally, it should be noted that the above is only 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 aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An energy-saving oxygen granular sludge sewage treatment system, characterized by: include: Wind and solar complementary energy supply module; An aerobic granular sludge sewage treatment module, comprising a grid tank, several biological reaction tanks, several self-lifting agitators, an aeration pump, and a PLC cabinet. Several of the biological reaction tanks are connected to the grid tank after being arranged in parallel. Several of the biological reaction tanks are equipped with self-lifting agitators, and several of the biological reaction tanks are connected to the aeration pump. The PLC cabinet is connected to the self-lifting agitators, the aeration pump, and the wind-solar complementary energy supply module. The assembled structural module includes a box body, the wind-solar complementary energy supply module is installed on the top of the box body, and the grid pool and the biological reaction pool are both built into the inner side of the box body.

2. The energy-saving oxygen granular sludge sewage treatment system according to claim 1 is characterized by: The wind-solar complementary energy supply module includes a wind generator, a solar power generation device, a wind-solar complementary controller, a battery and an inverter. The output end of the wind generator is connected to the wind-solar complementary controller, the output end of the solar power generation device is connected to the wind-solar complementary controller, the wind-solar complementary controller is connected to the battery, the battery is connected to the inverter, and the PLC cabinet is connected to the inverter.

3. The energy-saving oxygen granular sludge sewage treatment system according to claim 1 is characterized by: The biological reaction tank is a sequencing batch reactor with a height-to-diameter ratio of 1.5-3. Each sequencing batch reactor is provided with a water inlet pipe, a water outlet pipe and an aeration device.

4. The energy-saving oxygen granular sludge sewage treatment system according to claim 1 is characterized by: A partition, a vent cap and an inspection ladder are also installed inside the box body, and a manhole is provided at a position corresponding to the inspection ladder on the top of the box body.

5. The energy-saving oxygen granular sludge sewage treatment system according to claim 3 is characterized by: The self-lifting stirrer comprises a driving motor (2), a stirring frame (3), a limiting shaft (4), a clutch assembly (5), a return spring (6) and a conical limiting cylinder (9); The driving motor (2) is fixed to the inner top end of the sequencing batch reactor via a mounting frame (1); the limiting shaft (4) is coaxially fixed to the output end of the driving motor (2); the stirring frame (3) is vertically slidably sleeved on the outer side of the limiting shaft (4); and the top end of the stirring frame (3) is fixed to the conical limiting cylinder (9) via a connecting frame (7); The inner diameter of the conical limiting cylinder (9) gradually decreases from top to bottom, and the driving motor (2) is in a non-operating state, and the clutch assembly (5) is located at the bottom of the conical limiting cylinder (9); The clutch assembly (5) is fixed on the limiting shaft (4), and the clutch assembly (5) is located inside the conical limiting cylinder (9), and the return spring (6) is fixed between the clutch assembly (5) and the connecting frame (7).

6. The energy-saving oxygen granular sludge sewage treatment system according to claim 5 is characterized by: The stirring frame (3) comprises a limiting sleeve (31) and a plurality of stirring rods (32); the limiting sleeve (31) is vertically slidably sleeved on the outer side of the limiting shaft (4); and the inner side of the limiting sleeve (31) is a non-cylindrical cavity; the limiting sleeve (31) is fixed to the connecting frame (7); and the plurality of stirring rods (32) are fixed to the side ends of the limiting sleeve (31) at equal distances from top to bottom.

7. The energy-saving oxygen granular sludge sewage treatment system according to claim 6, characterized in that: A rotating blade (8) is coaxially fixed to the bottom end of the limiting sleeve (31), and a flexible protective sleeve (10) is sleeved on the outer side of the reset spring (6). The flexible protective sleeve (10) is fixed between the connecting frame (7) and the clutch assembly (5).

8. The energy-saving oxygen granular sludge sewage treatment system according to claim 5, characterized in that: The clutch assembly (5) includes a fixed sleeve (51) and a counterweight slider (52), wherein the fixed sleeve (51) is horizontally fixed to the side end of the limiting shaft (4), and the counterweight slider (52) is horizontally slidably sleeved on the inner side of the fixed sleeve (51), and the end of the counterweight slider (52) away from the limiting shaft (4) passes through the fixed sleeve (51), and the counterweight slider (52) is equidistantly mounted with a plurality of balls (53) on the side end along the sliding direction thereof.

9. A sewage treatment method based on the energy-saving oxygen granular sludge sewage treatment system according to claim 1, characterized in that: The following steps are involved: Step 1: The sewage passes through the grid pool and enters the biological reaction pool; Step 2: maintaining the bioreactor in an anaerobic environment and stirring the bioreactor using the self-lifting stirrer to maintain the reaction for a first preset time; Step 3: Turn on the aeration pump to keep the biological reaction tank in an aerobic environment and stir it, so that the reaction continues for a second preset time; Step 4: Turn off the aeration pump, keep the biological reaction tank in an anoxic environment and stir, and keep the reaction for a third preset time; Step 5: turning off the self-lifting agitator to allow the mixture in the bioreactor to settle for a fourth preset time; Step 6: The supernatant obtained by settling is discharged according to a set ratio, and the remaining sludge and clear liquid remain in the biological reaction tank; Step 7, repeating steps 1 to 6, each time shortening the fourth preset time, until aerobic granular sludge is formed in the bioreactor; Step 8: Keep the fourth preset time during the formation of aerobic granular sludge unchanged and repeat steps 1 to 6.

10. The energy-saving oxygen granular sludge sewage treatment method according to claim 9, characterized in that: The first preset time duration is 1-3 hours, the second preset time duration is 0.5-2 hours, the third preset time duration is 1-3 hours, and the fourth preset time duration is 0.1-0.5 hours; The discharge ratio of the supernatant in step 6 is 20-80% of the total volume.

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