Reflux ratio control device for double-reflux AOA process

Abstract

The invention discloses a reflux ratio control device for a double-reflux AOA process, and relates to the technical field of sewage treatment.The reflux ratio control device comprises an anaerobic tank, an aerobic tank, an anoxic tank and a secondary sedimentation tank which are sequentially distributed from left to right, and the anaerobic tank, the aerobic tank, the anoxic tank and the secondary sedimentation tank are sequentially connected in series through a sewage transfer assembly; the reflux ratio control device further comprises a sludge discharge position control mechanism, an upper-layer sludge reflux mechanism and a lower-layer sludge reflux mechanism, the sludge discharge position control mechanism comprises a sludge discharge rotating pipe, and the center of the bottom of the secondary sedimentation tank is rotationally connected with the bottom end of the sludge discharge rotating pipe. The sludge close to the lower layer in the secondary sedimentation tank can flow back into the anoxic tank, and the sludge close to the upper layer in the secondary sedimentation tank can flow back into the anaerobic tank, so that the sludge with higher nitrate content close to the lower layer in the secondary sedimentation tank is prevented from flowing back into the anaerobic tank; the mixing efficiency of the sludge flowing back to the anaerobic tank and the anoxic tank and the sewage entering the tank or the original sewage in the tank is high, so that the treatment efficiency of the sewage is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a reflux ratio control device for a double-reflux AOA process. Background Art

[0002] The sludge double-return AOA process is a new type of high-efficiency denitrification process. The process includes an anaerobic tank, an aerobic tank, an anoxic tank and a secondary sedimentation tank connected in sequence. The sludge in the secondary sedimentation tank is returned in two ways, one way is returned to the front end of the anaerobic tank, and the other way is returned to the front end of the anoxic tank. In this process, part of the return sludge is introduced into the anaerobic tank to maintain the concentration balance of microorganisms in the anaerobic tank. The microorganisms in the sludge decompose organic matter under anaerobic conditions, releasing orthophosphate in the cells. At the same time, they generate energy by breaking down glycogen and store internal carbon sources in the cells. These internal carbon sources are then used in the anoxic tank for denitrification, thereby reducing dependence on external carbon sources and improving denitrification efficiency. The secondary return sludge, which flows back to the anoxic tank, not only provides an internal carbon source for denitrification in the anoxic tank but also increases the number of denitrifying bacteria in the tank. The denitrifying bacteria in the return sludge can utilize the internal carbon source and other organic matter in the anoxic environment of the anoxic tank to carry out denitrification reactions, converting nitrates into nitrogen gas. This process requires no external carbon source and offers high denitrification efficiency, making it particularly suitable for denitrification of wastewater with a low carbon-to-nitrogen ratio.

[0003] At present, many sewage treatment plants do not distinguish between upper and lower layers of sludge during sludge return, which easily leads to the return of sludge with higher nitrate content in the lower layer to the anaerobic tank, affecting the growth and activity of anaerobic microorganisms and interfering with the anaerobic phosphorus release reaction. In addition, the sludge returned to the anaerobic tank and the anoxic tank has low mixing efficiency with the sewage in the original tank, which will affect the denitrification and phosphorus removal efficiency of the sewage. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the existing defects and provide a reflux ratio control device for a double-reflux AOA process, which can return the sludge near the lower layer in the secondary sedimentation tank to the anoxic tank, and return the sludge near the upper layer in the secondary sedimentation tank to the anaerobic tank, so as to avoid the sludge with a higher nitrate content near the lower layer in the secondary sedimentation tank from flowing back into the anaerobic tank, thereby avoiding affecting the growth and activity of anaerobic microorganisms and interfering with the anaerobic phosphorus release reaction. The sludge returned to the anaerobic tank and the anoxic tank is mixed with the sewage entering the tank or the original sewage in the tank at a high efficiency, which is beneficial to improving the denitrification and phosphorus removal efficiency of the sewage, and can effectively solve the problems in the background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a reflux ratio control device for a double reflux AOA process, comprising an anaerobic tank, an aerobic tank, an anoxic tank, and a secondary sedimentation tank, which are sequentially distributed from left to right, and the anaerobic tank, the aerobic tank, the anoxic tank, and the secondary sedimentation tank are sequentially connected in series through a sewage transfer component, and further comprising: The mud discharge position control mechanism includes a mud discharge rotating pipe. The bottom center of the secondary sedimentation tank is rotatably connected to the bottom end of the mud discharge rotating pipe. The mud discharge rotating pipe is located at the bottom of the secondary sedimentation tank and is provided with a lower mud discharge hole. The mud discharge rotating pipe is provided with an upper mud discharge hole in a circular array above the lower mud discharge hole. A baffle is provided between the upper mud discharge hole and the lower mud discharge hole in the mud discharge rotating pipe. An upper sludge return mechanism has one end connected to the top of the sludge discharge pipe, and the other end of the upper sludge return mechanism extends to the front end of the water inlet in the anaerobic tank; One end of the lower sludge return mechanism is connected to the bottom end of the sludge discharge transfer pipe, and the other end of the lower sludge return mechanism extends to the front end of the water inlet in the anoxic tank.

[0006] The external sewage is sent into the anaerobic tank through the sewage transfer component at the front end of the anaerobic tank inlet, and then the anaerobic reaction is carried out in the anaerobic tank. The sewage in the anaerobic tank is sent to the aerobic tank through the sewage transfer component for aerobic reaction. The sewage in the aerobic tank is sent to the anoxic tank through the sewage transfer component for reaction. The sewage in the anoxic tank is then sent to the secondary sedimentation tank by the sewage transfer component for sedimentation. The sludge is settled at the bottom of the secondary sedimentation tank. The sludge in the secondary sedimentation tank is returned to the anaerobic tank and the anoxic tank respectively through the sludge discharge position control mechanism, the upper sludge return mechanism and the lower sludge return mechanism to supplement the activated sludge lost in the anaerobic tank and the anoxic tank due to the effluent, ensuring that the activated sludge in the reaction tank is stable within a reasonable range, providing sufficient biomass support for the degradation of organic matter by microorganisms. Generally, the sludge is returned to the anaerobic tank and the anoxic tank. The sludge return ratio to the anaerobic tank is generally 50% to 100%, and the sludge return ratio to the anoxic tank is 30%-100%. Adjusting the sludge return ratio can optimize the microbial metabolic pathway, fully utilize the raw water carbon source, and reduce the need for external agents, thereby achieving the goal of deep denitrification and phosphorus removal. The lower sludge return mechanism sucks the lower layer of sludge settled in the secondary sedimentation tank through the area below the baffle and the lower sludge discharge holes in the sludge discharge pipe and sends it to the anoxic tank. The upper sludge return mechanism sucks the upper layer of sludge settled in the secondary sedimentation tank through the area above the baffle and the upper sludge discharge holes in the sludge discharge pipe and sends it to the anaerobic tank. The rotating power component is used to drive the sludge discharge pipe to rotate in the secondary sedimentation tank, which can drive the lower sludge discharge holes to rotate, and can expand the range of suction of the lower layer sludge. Furthermore, the mud discharge position control mechanism also includes a scraper and discharge cover and a support return pipe. The lower mud discharge holes are connected to two scraper and discharge covers through two support return pipes respectively. The two scraper and discharge covers are arranged side by side on the left and right, and the bottoms of the two scraper and discharge covers are close to the bottom of the secondary sedimentation tank. The sludge scraping hood is driven by the support return pipe to rotate at the bottom of the secondary sedimentation tank, and the sludge at the bottom of the secondary sedimentation tank is quickly introduced into the sludge scraping hood, and then is pumped away through the support return pipe and the lower sludge return mechanism. The sludge scraping hood cooperates with the rotating power component and the sludge discharge rotating pipe to also play the role of scraping sludge, which can ensure that the lower sludge return mechanism can fully pump away the sludge settled in the lower layer of the secondary sedimentation tank.

[0007] Furthermore, the sludge discharge position control mechanism further includes a conical sludge spacer and a first sealing rubber ring. The conical sludge spacer is positioned at the bottom of the secondary sedimentation tank, and a first sealing rubber ring is installed between the bottom of the conical sludge spacer and the bottom of the secondary sedimentation tank. The conical sludge spacer is used to occupy the area within the conical structure at the bottom of the secondary sedimentation tank, preventing sludge from settling in this area, which would make it difficult for the scraper to remove sludge from this area. The first sealing rubber ring prevents sewage from entering the center bottom of the secondary sedimentation tank and, in conjunction with the first sealing bearing, prevents sewage from leaking from the connection between the secondary sedimentation tank and the sludge discharge pipe.

[0008] Furthermore, the upper sludge return mechanism includes an upper sludge pumping assembly and an anaerobic tank sludge conveying assembly. The top of the sludge discharge pipe is connected to one end of the upper sludge pumping assembly, and the other end of the upper sludge pumping assembly is connected to the front end of the return mud layer switching mechanism. The right end of the return mud layer switching mechanism is connected to one end of the anaerobic tank sludge conveying assembly, and the other end of the anaerobic tank sludge conveying assembly extends to the front end of the water inlet in the anaerobic tank.

[0009] Furthermore, the lower layer sludge return mechanism includes a lower layer sludge pumping assembly and an anoxic tank sludge conveying assembly. The bottom end of the sludge discharge pipe is connected to one end of the lower layer sludge pumping assembly, and the other end of the lower layer sludge pumping assembly is connected to the rear end of the return mud layer switching mechanism. The left end of the return mud layer switching mechanism is connected to one end of the anoxic tank sludge conveying assembly, and the other end of the anoxic tank sludge conveying assembly extends to the front end of the water inlet in the anoxic tank.

[0010] The upper sludge pumping assembly cooperates with the upper sludge discharge hole on the sludge discharge rotating pipe to extract the upper sludge settled in the secondary sedimentation tank. The lower sludge pumping assembly cooperates with the lower sludge discharge hole, the scraper sludge discharge cover and the support return pipe on the sludge discharge rotating pipe to extract the lower sludge settled in the secondary sedimentation tank. Under normal circumstances, the return mud layer switching mechanism sends the upper sludge sent by the upper sludge pumping assembly into the anaerobic tank through the anaerobic tank sludge conveying assembly, and sends the lower sludge sent by the lower sludge pumping assembly into the anoxic tank through the anoxic tank sludge conveying assembly. Detect the sludge concentration in the anaerobic tank. When the sludge concentration and microbial concentration in the anaerobic tank are low, the function of the return mud layer switching mechanism is switched to: the upper sludge sent out by the upper sludge pumping component is sent into the anoxic tank through the anoxic tank sludge conveying component, and the lower sludge sent out by the lower sludge pumping component is sent into the anaerobic tank through the anaerobic tank sludge conveying component. While maintaining the original sludge return ratio, the sludge concentration and microbial concentration in the anaerobic tank can be quickly increased due to the high concentration of the lower sludge in the secondary sedimentation tank. It should be noted that this situation is applicable to the state where the overall nitrate content in the secondary sedimentation tank is low.

[0011] Furthermore, the reflow mud layer switching mechanism includes a shell, a circular switching groove, a switching plate, a circular plate, a shell cover and a switching motor. A circular switching groove is opened in the middle of the shell, and a shell cover is installed on the top of the shell. A switching motor is installed in the middle of the shell cover. The bottom output shaft of the switching motor extends into the circular switching groove and is fixedly connected to the top center of the switching plate. The two ends of the switching plate are respectively provided with arc surfaces that cooperate with the side walls of the circular switching groove. Two circular plates are respectively provided on the upper and lower sides of the switching plate. When the backflow stops, the upper sludge pumping assembly and the lower sludge pumping assembly stop working, the switching motor keeps the switching plate in a horizontal state, and the two arc surfaces at both ends of the switching plate block the circular holes on the left and right sides of the shell. When the backflow starts, the switching motor drives the switching plate and the two circular plates to rotate 45 degrees counterclockwise, and the sludge diversion chamber 1 connects the upper sludge pumping assembly and the anaerobic tank sludge conveying assembly, and the sludge pumped out by the upper sludge pumping assembly is sent into the anaerobic tank through the anaerobic tank sludge conveying assembly. The sludge diversion chamber 2 connects the lower sludge pumping assembly and the anoxic tank sludge conveying assembly, and the sludge pumped out by the lower sludge pumping assembly is sent into the anoxic tank through the anoxic tank sludge conveying assembly. When the sludge concentration and microbial concentration in the anaerobic tank are low, the switching motor drives the switching plate and the two circular plates to rotate 90 degrees clockwise. The sludge diversion chamber 1 connects the upper sludge pumping assembly and the anoxic tank sludge conveying assembly, and the sludge pumped out by the upper sludge pumping assembly is sent into the anoxic tank through the anoxic tank sludge conveying assembly. The sludge diversion chamber 2 connects the lower sludge pumping assembly and the anaerobic tank sludge conveying assembly, and the sludge pumped out by the lower sludge pumping assembly is sent into the anaerobic tank through the anaerobic tank sludge conveying assembly.

[0012] Furthermore, it also includes a return sludge inlet water convection mixing mechanism, which includes a mixing box, a control solenoid valve and a discharge trough. The anaerobic tank sludge conveying component is located at one end in the anaerobic tank and the anoxic tank sludge conveying component is located at one end in the anoxic tank, which are respectively connected to the bottom inlets of the two mixing boxes through two control solenoid valves. A discharge trough is respectively opened in the middle of the right side of each mixing box, and the top of each mixing box is respectively connected to the corresponding sewage transfer component. Open control solenoid valve 1, and the sludge in the anaerobic tank sludge conveying component and the anoxic tank sludge conveying component enter the bottom of the two mixing boxes respectively. Specifically: the anaerobic tank sludge conveying component sends the sludge into the bottom of the mixing box in the anaerobic tank, and the sewage transfer component sends the external sewage into the top of the mixing box in the anaerobic tank. The external sewage is quickly mixed with the sludge at the bottom of the mixing box in the anaerobic tank, and is discharged into the anaerobic tank through the discharge chute. The anoxic tank sludge conveying component sends the sludge into the bottom of the mixing box in the anoxic tank, and the sewage transfer component between the aerobic tank and the anoxic tank sends the sewage in the aerobic tank into the top of the mixing box in the anoxic tank. The sewage here is quickly mixed with the sludge at the bottom of the mixing box in the anoxic tank, and is discharged into the anoxic tank through the discharge chute; it can promote the rapid mixing of the returned sludge with the sewage in the original tank, which is beneficial to improving the sewage treatment efficiency.

[0013] Furthermore, the return sludge inlet water convection mixing mechanism also includes a semicircular baffle, a horizontal baffle, mud holes and water holes. A semicircular baffle is arranged in the middle of the left side of the mixing box. The upper half of the semicircular baffle is evenly provided with water holes, and the lower half of the semicircular baffle is evenly provided with mud holes. The upper and lower ends of the semicircular baffle are respectively fixedly connected to the left ends of the two horizontal baffles, and the right ends of the two horizontal baffles are respectively connected to the upper and lower ends of the discharge trough. The semicircular baffle and the two horizontal baffles constitute a convection mixing bin.

[0014] The sludge enters the mud inlet chamber of the mixing box through the control solenoid valve, and the sludge is dispersed into the convection mixing chamber through the mud holes. The sewage enters the water inlet chamber of the mixing box through the sewage transfer component, and then the sewage is dispersed into the convection mixing chamber through the water holes. The dispersed sewage and dispersed sludge fully convect, mix quickly, and mix evenly. This process is suitable for situations where there is a sewage transfer component to transport sewage into the mixing box.

[0015] Furthermore, the invention also includes a return sludge inlet and stirring mechanism, which includes a rotating drum, a stirring outer frame, a stirring inner frame and a rotating shaft. A longitudinal rotating drum is rotatably installed in the middle of the front end of each mixing box. The rotating drum is rotatably connected to the rotating shaft. The rear end of the rotating drum is connected to the stirring outer frame. The rear end of the rotating shaft is connected to the stirring inner frame. The stirring inner frame is located on the inner side of the stirring outer frame, and the stirring outer frame and the stirring inner frame are both located in the corresponding convection mixing chamber. The front end of the rotating drum and the front end of the rotating shaft are connected to an opposing drive assembly. The opposing drive assembly drives the rotating drum and the rotating shaft to rotate in opposite directions, thereby driving the stirring outer frame and the stirring inner frame to rotate in opposite directions in the convection mixing chamber, which is beneficial to fully stirring the sludge and sewage in the convection mixing chamber and promoting rapid mixing of the sludge and sewage.

[0016] Furthermore, it also includes a return sludge discharge stirring mechanism, which includes a stirring vertical pipe. The anaerobic tank sludge conveying component is located at one end in the anaerobic tank, and the anoxic tank sludge conveying component is located at one end in the anoxic tank, which are respectively connected to the bottom ends of the two bent pipes. A control solenoid valve 2 is installed in the middle of each bent pipe. The top of each bent pipe is connected to the bottom end of the stirring vertical pipe through a rotary joint 3. The top of each stirring vertical pipe is connected to the stirring drive assembly. The side of each stirring vertical pipe is connected to a vertical stirring pipe through a radial pipe. The stirring pipe is provided with a mud discharge trough at equal vertical distances on one side away from the stirring vertical pipe. When the sewage transfer component does not transport sewage into the mixing tank and the sludge flows back into the mixing tank, the control solenoid valve 1 is closed and the control solenoid valve 2 is opened. The sludge is sent into the stirring vertical pipe through the elbow and the rotary joint 3, and then into the stirring pipe through the radial pipe. It is dispersed and discharged into the corresponding anaerobic tank or anoxic tank through the mud outlet trough. The stirring drive component drives the stirring vertical pipe, radial pipe and stirring pipe to rotate. The rotary joint 3 ensures that the rotating stirring vertical pipe and the elbow can still have medium conduction. The radial pipe and stirring pipe are also used as stirring rods. The sludge dispersed into the tank body through the mud outlet trough is fully stirred with the sewage in the tank body to achieve full mixing of the sewage and the sludge.

[0017] Compared with the prior art, the beneficial effects of the reflux ratio control device for the double reflux AOA process are: 1. The return ratio control device for the double-return AOA process, the sludge in the secondary sedimentation tank is returned to the anaerobic tank and the anoxic tank respectively through the sludge discharge position control mechanism, the upper sludge return mechanism and the lower sludge return mechanism, to replenish the activated sludge lost in the anaerobic tank and the anoxic tank due to effluent, to ensure that the activated sludge in the reaction tank is stable within a reasonable range, and to provide sufficient biomass support for microbial degradation of organic matter. Generally, the sludge return ratio to the anaerobic tank is 50% to 100%, and the sludge return ratio to the anoxic tank is 30%-100%. It can optimize the microbial metabolic pathway, make full use of the raw water carbon source, reduce the demand for external agents, and thus achieve the goal of deep denitrification and phosphorus removal.

[0018] 2. The reflux ratio control device for the double-reflux AOA process has a lower sludge reflux mechanism that sucks away the sludge in the lower layer of the secondary sedimentation tank through the area below the baffle and the lower sludge discharge hole in the sludge discharge pipe and sends it into the anoxic tank. The upper sludge reflux mechanism sucks away the sludge in the upper layer of the secondary sedimentation tank through the area above the baffle and the upper sludge discharge hole in the sludge discharge pipe and sends it into the anaerobic tank. The rotary power component is used to drive the sludge discharge pipe to rotate in the secondary sedimentation tank. The lower sludge discharge hole cooperates with the support return pipe and the sludge scraping hood to expand the range of sucking the lower layer of sludge. The sludge scraping hood cooperates with the rotary power component and the sludge discharge pipe to also scrape the sludge, thereby ensuring that the lower sludge reflux mechanism fully extracts the sludge settled in the lower layer of the secondary sedimentation tank.

[0019] 3. The return ratio control device for the double-return AOA process detects the sludge concentration in the anaerobic tank. When the sludge concentration and microbial concentration in the anaerobic tank are low, the function of the return mud layer switching mechanism is switched to: the upper sludge sent out by the upper sludge pumping component is sent into the anoxic tank through the anoxic tank sludge conveying component, and the lower sludge sent out by the lower sludge pumping component is sent into the anaerobic tank through the anaerobic tank sludge conveying component. While maintaining the original sludge return ratio, the sludge concentration and microbial concentration in the anaerobic tank can be quickly increased due to the high concentration of the lower sludge in the secondary sedimentation tank.

[0020] 4. The sludge enters the mud inlet chamber of the mixing box through the control solenoid valve, and the sludge is dispersed into the convection mixing chamber through the mud holes. The sewage enters the water inlet chamber of the mixing box through the sewage transfer component, and then the sewage is dispersed into the convection mixing chamber through the water holes. The dispersed sewage and the dispersed sludge fully convect and mix quickly and evenly. The counter-drive component drives the drum and the shaft to rotate in opposite directions, thereby driving the outer mixing frame and the inner mixing frame to rotate in opposite directions in the convection mixing chamber, which is beneficial to fully mixing the sludge and sewage in the convection mixing chamber and promoting rapid mixing of the sludge and sewage.

[0021] 5. The return ratio control device for the double-return AOA process can return the sludge near the lower layer in the secondary sedimentation tank to the anoxic tank, and return the sludge near the upper layer in the secondary sedimentation tank to the anaerobic tank, so as to prevent the sludge with a high nitrate content near the lower layer in the secondary sedimentation tank from returning to the anaerobic tank, thereby avoiding affecting the growth and activity of anaerobic microorganisms and interfering with the anaerobic reaction. The sludge returned to the anaerobic tank and the anoxic tank is mixed with the sewage entering the tank or the original sewage in the tank at a high efficiency, which is beneficial to improving the denitrification and phosphorus removal efficiency of the sewage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of the reflux ratio control device for the double reflux AOA process of the present invention; Figure 2 For the present invention Figure 1 A schematic diagram of the partially enlarged structure at center A; Figure 3 For the present invention Figure 1 Schematic diagram of the structure from a top view; Figure 4 Schematic diagram of the cross-sectional structure of the secondary sedimentation tank and the sludge discharge position control mechanism in the present invention; Figure 5 For the present invention Figure 4 A schematic diagram of the partially enlarged structure at point B in the middle; Figure 6 It is a partial structural diagram of the mud discharge position control mechanism in the present invention; Figure 7 Schematic diagram of the explosion structure of the reflux mud layer switching mechanism in the present invention; Figure 8 Schematic diagram of the local structure of the present invention Figure 1 ; Figure 9 Schematic diagram of the local structure of the present invention Figure 2 ; Figure 10 Schematic diagram of the cross-sectional structure of the return sludge inlet water convection mixing mechanism of the present invention; Figure 11 For the present invention Figure 10 A schematic diagram of the partially enlarged structure at point C in the middle; In the figure: 1 Secondary sedimentation tank, 2 Mud discharge position control mechanism, 21 Secondary sedimentation tank crossbeam, 22 Crossbeam bearing, 23 Mud discharge rotary pipe, 24 Driven gear, 25 Driving gear, 26 Control motor, 27 Sealed bearing 1, 28 Conical sludge spacer, 29 Sealing rubber ring 1, 210 Baffle, 211 Upper mud discharge hole, 212 Mud scraper cover, 213 Support return pipe, 214 Lower mud discharge hole, 3 Upper mud return mechanism, 31 Rotary joint 1, 32 Upper return pipe 1, 3 3 Upper mud pump, 34 Upper return pipe 2, 35 Upper return pipe 3, 36 Upper return solenoid valve, 37 Upper mud flow meter, 4 Lower sludge return mechanism, 41 Rotary joint 2, 42 Lower return pipe 1, 43 Lower mud pump, 44 Lower return pipe 2, 45 Lower return pipe 3, 46 Lower return solenoid valve, 47 Lower mud flow meter, 5 Return mud layer switching mechanism, 51 Shell, 52 Round switching groove, 53 Switching plate, 54 Round plate, 55 Shell cover, 56 Bracket, 57 switching motor, 58 shell cover bolt, 59 sealing rubber ring 2, 6 return sludge water inlet convection mixing mechanism, 61 mixing box, 62 box frame, 63 control solenoid valve 1, 64 discharge channel, 65 semicircular arc partition, 66 horizontal partition, 67 mud hole, 68 water hole, 7 return sludge water inlet stirring mechanism, 71 sealed bearing 2, 72 rotating drum, 73 bevel gear 1, 74 bevel gear 2, 75 driving bevel gear, 76 stirring motor, 77 motor base, 78 stirring outer frame, 79 stirring inner frame, 710 rotating shaft, 8 return sludge discharge stirring mechanism, 81 elbow, 82 control solenoid valve 2, 83 rotary joint 3, 84 longitudinal beam, 85 stirring motor, 86 stirring vertical pipe, 87 radial pipe, 88 stirring pipe, 89 mud discharge trough, 9 sewage transfer assembly, 91 sewage pump, 92 discharge pipe, 93 water inlet pipe, 11 anaerobic tank, 12 aerobic tank, 13 anoxic tank, 14 sewage flow meter, 15 ultrasonic mud level meter, 16 mud discharge pipe, 17 mud discharge solenoid valve. DETAILED DESCRIPTION

[0023] 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.

[0024] For example 1, please refer to Figures 1 to 11This embodiment provides a technical solution: a reflux ratio control device for a double-reflux AOA process, comprising an anaerobic tank 11, an aerobic tank 12, an anoxic tank 13 and a secondary sedimentation tank 1, which are distributed from left to right. The secondary sedimentation tank 1 is cylindrical, and the bottom of the secondary sedimentation tank 1 is a conical structure. The anaerobic tank 11, the aerobic tank 12, the anoxic tank 13 and the secondary sedimentation tank 1 are connected in series through a sewage transfer component 9, and a sewage transfer component 9 is also installed at the left end of the anaerobic tank 11. It also includes a sludge discharge position control mechanism 2, an upper sludge return mechanism 3 and a lower sludge return mechanism 4.

[0025] The sewage transfer assembly 9 includes a sewage pump 91, a discharge pipe 92 and an inlet pipe 93. The water inlet of the sewage pump 91 is connected to the inlet pipe 93, and the water outlet of the sewage pump 91 is connected to the discharge pipe 92. The sewage transfer assembly 9 at the left end of the anaerobic tank 11 is used to send external sewage into the left end of the anaerobic tank 11. The sewage transfer assembly 9 between the anaerobic tank 11 and the aerobic tank 12 is used to send the sewage in the anaerobic tank 11 into the aerobic tank 12. The sewage transfer assembly 9 between the aerobic tank 12 and the anoxic tank 13 is used to send the sewage in the aerobic tank 12 into the anoxic tank 13. The sewage transfer assembly 9 between the anoxic tank 13 and the secondary sedimentation tank 1 is used to send the sewage in the anoxic tank 13 into the secondary sedimentation tank 1.

[0026] It also includes a sewage flow meter 14. The sewage flow meter 14 is installed on the discharge pipe 92 to monitor the sewage flow transferred by the sewage transfer component 9 and is also used to calculate the sludge return ratio.

[0027] The mud discharge position control mechanism 2 includes a rotary power component, a mud discharge rotating pipe 23, a sealed bearing 27, a baffle 210, an upper mud discharge hole 211 and a lower mud discharge hole 214. The bottom center of the secondary sedimentation tank 1 is rotatably connected to the bottom end of the mud discharge rotating pipe 23 through a sealed bearing 27. The top of the mud discharge rotating pipe 23 is connected to the rotary power component. The mud discharge rotating pipe 23 is located at the bottom of the secondary sedimentation tank 1 and is provided with a lower mud discharge hole 214. The mud discharge rotating pipe 23 is provided with an upper mud discharge hole 211 in a circular array above the lower mud discharge hole 214. A baffle 210 is provided in the mud discharge rotating pipe 23 between the upper mud discharge hole 211 and the lower mud discharge hole 214. The mud discharge position control mechanism 2 also includes a secondary sedimentation tank beam 21 and a beam bearing 22. The secondary sedimentation tank beam 21 is installed on the top of the secondary sedimentation tank 1. The middle part of the secondary sedimentation tank beam 21 is rotatably connected to the top of the mud discharge rotating pipe 23 through the beam bearing 22. The secondary sedimentation tank beam 21 and the beam bearing 22 improve the stability of the mud discharge rotating pipe 23 during rotation.

[0028] It also includes an ultrasonic mud level meter 15, which is installed on the secondary sedimentation tank beam 21. The ultrasonic mud level meter 15 is close to the inner wall of the secondary sedimentation tank 1. The ultrasonic mud level meter 15 is used to monitor the sludge thickness in the secondary sedimentation tank 1 and can control the change of the sludge return ratio according to the sludge thickness in the secondary sedimentation tank 1.

[0029] The rotating power assembly includes a driven gear 24, a driving gear 25 and a control motor 26. The driven gear 24 is fixedly installed on the top of the mud discharge rotating pipe 23, and the control motor 26 is installed on the secondary sedimentation tank beam 21. The output shaft of the control motor 26 is installed with the driving gear 25. The driving gear 25 is meshed and connected with the driven gear 24. When the control motor 26 works, the mud discharge rotating pipe 23 is driven to rotate through the transmission of the driven gear 24 and the driving gear 25.

[0030] The sludge discharge position control mechanism 2 also includes a scraper sludge discharge cover 212 and a support return pipe 213. The lower layer sludge discharge hole 214 is connected to the two scraper sludge discharge covers 212 through two support return pipes 213. The two scraper sludge discharge covers 212 are arranged side by side on the left and right, and the bottoms of the two scraper sludge discharge covers 212 are close to the bottom of the secondary sedimentation tank 1. When the sludge discharge rotating pipe 23 rotates in the secondary sedimentation tank 1, it can drive the scraper sludge discharge covers 212 to rotate through the support return pipe 213. The two scraper sludge discharge covers 212 arranged side by side form a scraper that can scrape up the sludge at the bottom of the secondary sedimentation tank 1. The lower layer sludge return mechanism 4 works, and the lower layer sludge settled in the secondary sedimentation tank 1 enters the scraper sludge discharge cover 212, and then enters the area below the baffle 210 in the sludge discharge rotating pipe 23 through the support return pipe 213 and the lower layer sludge discharge hole 214, and then is sent into the anoxic tank 13 through the lower layer sludge return mechanism 4. At the left end, the sludge is returned to the anoxic tank 13. Since the rotating power component drives the sludge discharge pipe 23 to rotate in the secondary sedimentation tank 1, the scraper and discharge hood 212 is driven to rotate at the bottom of the secondary sedimentation tank 1. The sludge at the bottom of the secondary sedimentation tank 1 can be quickly introduced into the scraper and discharge hood 212, and then extracted through the supporting return pipe 213 and the lower sludge return mechanism 4. The scraper and discharge hood 212 cooperates with the rotating power component and the sludge discharge pipe 23 to also play the role of scraping sludge, which can ensure that the lower sludge return mechanism 4 can fully extract the sludge settled in the lower layer of the secondary sedimentation tank 1.

[0031] The sludge discharge position control mechanism 2 also includes a conical sludge spacer sleeve 28 and a sealing rubber ring 29. The sludge discharge rotating pipe 23 is located at the bottom of the secondary sedimentation tank 1 and is sleeved with the conical sludge spacer sleeve 28. The top diameter of the conical sludge spacer sleeve 28 is smaller than the bottom diameter, and the upper mud discharge hole 211 is located above the top of the conical sludge spacer sleeve 28. The support return pipe 213 passes through the conical sludge spacer sleeve 28, and a sealing rubber ring 29 is installed between the bottom of the conical sludge spacer sleeve 28 and the bottom of the secondary sedimentation tank 1. There are two sealing rubber rings 29, and the two sealing rubber rings 29 have different diameters but are arranged concentrically. The bottom of the conical sludge spacer sleeve 28 and the bottom of the secondary sedimentation tank 1 are respectively provided with annular grooves that cooperate with the sealing rubber ring 29. The conical sludge spacer sleeve 28 is used to occupy the area within the conical structure at the bottom of the secondary sedimentation tank 1 to prevent sludge from settling in this area, making it difficult for the sludge scraper and discharge cover 212 to extract the sludge in this area. The setting of the sealing rubber ring 29 can prevent sewage from entering the center bottom of the secondary sedimentation tank 1, and cooperate with the sealing bearing 27 to prevent sewage from leaking from the connection between the secondary sedimentation tank 1 and the sludge discharge pipe 23.

[0032] One end of the upper sludge return mechanism 3 is connected to the top of the sludge discharge pipe 23, and the other end of the upper sludge return mechanism 3 extends to the front end of the water inlet in the anaerobic tank 11; One end of the lower sludge return mechanism 4 is connected to the bottom end of the sludge discharge transfer pipe 23 , and the other end of the lower sludge return mechanism 4 extends to the front end of the water inlet in the anoxic tank 13 .

[0033] The upper sludge return mechanism 3 includes an upper sludge pumping assembly and an anaerobic tank sludge conveying assembly. The top of the sludge discharge pipe 23 is connected to one end of the upper sludge pumping assembly, and the other end of the upper sludge pumping assembly is connected to the front end of the return mud layer switching mechanism 5. The right end of the return mud layer switching mechanism 5 is connected to one end of the anaerobic tank sludge conveying assembly, and the other end of the anaerobic tank sludge conveying assembly extends to the water inlet front end of the anaerobic tank 11.

[0034] The lower layer sludge return mechanism 4 includes a lower layer sludge pumping assembly and an anoxic tank sludge conveying assembly. The bottom end of the sludge discharge pipe 23 is connected to one end of the lower layer sludge pumping assembly, and the other end of the lower layer sludge pumping assembly is connected to the rear end of the return mud layer switching mechanism 5. The left end of the return mud layer switching mechanism 5 is connected to one end of the anoxic tank sludge conveying assembly, and the other end of the anoxic tank sludge conveying assembly extends to the front end of the water inlet in the anoxic tank 13.

[0035] The upper sludge pumping assembly cooperates with the upper sludge discharge hole 211 on the sludge discharge rotating pipe 23 to extract the upper sludge settled in the secondary sedimentation tank 1. The lower sludge pumping assembly cooperates with the lower sludge discharge hole 214, the sludge scraping and discharge cover 212 and the support return pipe 213 on the sludge discharge rotating pipe 23 to extract the lower sludge settled in the secondary sedimentation tank 1. Under normal circumstances, the return mud layer switching mechanism 5 sends the upper sludge sent by the upper sludge pumping assembly into the anaerobic tank 11 through the anaerobic tank sludge conveying assembly, and sends the lower sludge sent by the lower sludge pumping assembly into the anoxic tank 13 through the anoxic tank sludge conveying assembly. The sludge concentration in the anaerobic tank 11 is detected. When the sludge concentration and microbial concentration in the anaerobic tank 11 are low, the function of the return mud layer switching mechanism 5 is switched to: the upper sludge sent out by the upper sludge pumping component is sent into the anoxic tank 13 through the anoxic tank sludge conveying component, and the lower sludge sent out by the lower sludge pumping component is sent into the anaerobic tank 11 through the anaerobic tank sludge conveying component. While maintaining the original sludge return ratio, the sludge concentration and microbial concentration in the anaerobic tank 11 can be quickly increased due to the high concentration of the lower sludge in the secondary sedimentation tank 1. It should be noted that this situation is applicable to the state where the overall nitrate content in the secondary sedimentation tank 1 is low.

[0036] The return mud layer switching mechanism 5 includes a shell 51, a circular switching groove 52, a switching plate 53, a circular plate 54, a shell cover 55 and a switching motor 57. A circular switching groove 52 is opened in the middle of the shell 51, and a shell cover 55 is installed on the top of the shell 51. A switching motor 57 is installed in the middle of the shell cover 55. The bottom output shaft of the switching motor 57 extends into the circular switching groove 52 and is fixedly connected to the top center of the switching plate 53. The two ends of the switching plate 53 are respectively provided with arc surfaces that cooperate with the side walls of the circular switching groove 52. Two circular plates 54 are respectively provided on the upper and lower sides of the switching plate 53. The outer peripheral sides of the two circular plates 54 respectively cooperate with the inner walls of the circular switching groove 52. The area between the two circular plates 54 is divided by the switching plate 53 into a front sludge diversion chamber 1 and a rear sludge diversion chamber 2.

[0037] The reflux mud layer switching mechanism 5 also includes a bracket 56, a shell cover bolt 58, and a sealing rubber ring 59. The top of the shell 51 is fixedly connected to the shell cover 55 by the shell cover bolt 58. The switching motor 57 is installed on the shell cover 55 through the bracket 56. A sealing rubber ring 59 is installed between the upper circular plate 54 and the top of the circular switching groove 52. The outer peripheral side of the upper circular plate 54 and the top of the circular switching groove 52 are respectively provided with annular mounting grooves that cooperate with the sealing rubber ring 59. The sealing rubber ring 59 is used to improve the sealing between the upper circular plate 54 and the circular switching groove 52.

[0038] When the backflow stops, the upper sludge pumping assembly and the lower sludge pumping assembly stop working, the switching motor 57 keeps the switching plate 53 in a horizontal state, and the two arc surfaces at both ends of the switching plate 53 block the circular holes on the left and right sides of the shell 51. When the backflow starts, the switching motor 57 drives the switching plate 53 and the two circular plates 54 to rotate 45 degrees counterclockwise, and the sludge diversion chamber 1 connects the upper sludge pumping assembly and the anaerobic tank sludge conveying assembly. The sludge pumped out by the upper sludge pumping assembly is sent into the anaerobic tank 11 through the anaerobic tank sludge conveying assembly. The sludge diversion chamber 2 connects the lower sludge pumping assembly and the anoxic tank sludge conveying assembly. The sludge pumped out by the lower sludge pumping assembly is sent into the anoxic tank 13 through the anoxic tank sludge conveying assembly. When the sludge concentration and microorganism concentration in the anaerobic tank 11 are low, the switching motor 57 drives the switching plate 53 and the two circular plates 54 to rotate clockwise 90 degrees. The sludge diversion chamber 1 connects the upper sludge pumping assembly and the anoxic tank sludge conveying assembly, and the sludge pumped out by the upper sludge pumping assembly is sent into the anoxic tank 13 through the anoxic tank sludge conveying assembly. The sludge diversion chamber 2 connects the lower sludge pumping assembly and the anaerobic tank sludge conveying assembly, and the sludge pumped out by the lower sludge pumping assembly is sent into the anaerobic tank 11 through the anaerobic tank sludge conveying assembly.

[0039] The upper sludge pumping assembly includes a rotary joint 31, an upper return pipe 32, an upper mud pump 33 and an upper return pipe 2 34. The top of the mud rotary pipe 23 is connected to one end of the upper return pipe 32 through the rotary joint 31, and the other end of the upper return pipe 32 is connected to the inlet of the upper mud pump 33. The outlet of the upper mud pump 33 is connected to the circular hole at the front end of the shell 51 through the upper return pipe 2 34. The upper mud pump 33 serves as the power source of the upper sludge pumping assembly and is used to extract the upper sludge settled in the secondary sedimentation tank 1.

[0040] The anaerobic tank sludge conveying assembly includes an upper return pipe three 35, an upper return solenoid valve 36 and an upper mud flowmeter 37. The circular hole at the right end of the shell 51 is connected to one end of the upper return pipe three 35, and the other end of the upper return pipe three 35 extends to the left end of the anaerobic tank 11. The upper return pipe three 35 is respectively installed with an upper return solenoid valve 36 and an upper mud flowmeter 37. The upper return solenoid valve 36 is used to control the on-off of the upper return pipe three 35, and the upper mud flowmeter 37 is used to measure the flow of sludge in the upper return pipe three 35.

[0041] The lower sludge pumping assembly includes a rotary joint 2 41, a lower return pipe 1 42, a lower sludge pump 43, and a lower return pipe 2 44. The bottom end of the sludge pump 23 is connected to one end of the lower return pipe 1 42 via the rotary joint 2 41. The other end of the lower return pipe 1 42 is connected to the inlet of the lower sludge pump 43. The outlet of the lower sludge pump 43 is connected to one end of the lower return pipe 2 44. The other end of the lower return pipe 2 44 is connected to the circular hole at the rear end of the housing 51. The lower sludge pump 43 serves as the power source for the lower sludge pumping assembly and is used to extract the lower sludge settled in the secondary sedimentation tank 1.

[0042] The anoxic tank sludge conveying assembly includes a lower layer return pipe three 45, a lower layer return solenoid valve 46 and a lower layer mud flow meter 47. The circular hole at the left end of the shell 51 is connected to one end of the lower layer return pipe three 45, and the other end of the lower layer return pipe three 45 extends to the left end of the anoxic tank 13. The lower layer return pipe three 45 is respectively installed with a lower layer return solenoid valve 46 and a lower layer mud flow meter 47. The lower layer return solenoid valve 46 is used to control the on and off of the lower layer return pipe three 45, and the lower layer mud flow meter 47 can measure the sludge flow in the lower layer return pipe three 45.

[0043] During use, external sewage is sent into the anaerobic tank 11 through the sewage transfer component 9 at the left end of the anaerobic tank 11, and then anaerobic reaction is carried out in the anaerobic tank 11, and then the sewage in the anaerobic tank 11 is sent into the aerobic tank 12 through the sewage transfer component 9 for aerobic reaction, and the sewage in the aerobic tank 12 is sent into the anoxic tank 13 through the sewage transfer component 9 for reaction, and then the sewage in the anoxic tank 13 is sent into the secondary sedimentation tank 1 by the sewage transfer component 9 for sedimentation, and the sludge is settled at the bottom of the secondary sedimentation tank 1. The sludge in the secondary sedimentation tank 1 is returned to the anaerobic tank 11 and the anoxic tank 13 respectively through the sludge discharge position control mechanism 2, the upper sludge return mechanism 3 and the lower sludge return mechanism 4, to supplement the activated sludge lost due to the effluent of the anaerobic tank 11 and the anoxic tank 13, to ensure that the activated sludge in the reaction tank is stable within a reasonable range, and to provide sufficient biomass support for the degradation of organic matter by microorganisms. The sludge return ratio to the anaerobic tank is generally 50% to 100%, and the sludge return ratio to the anoxic tank is 30%-100%. Adjusting the sludge return ratio can optimize the microbial metabolic pathway, make full use of the raw water carbon source, and reduce the need for external agents, thereby achieving the goal of deep denitrification and phosphorus removal. The lower sludge return mechanism 4 sucks the lower layer of sludge settled in the secondary sedimentation tank 1 into the anoxic tank 13 through the area below the baffle 210 in the sludge discharge pipe 23 and the lower sludge discharge hole 214. The upper sludge return mechanism 3 sucks the upper layer of sludge settled in the secondary sedimentation tank 1 into the anaerobic tank 11 through the area above the baffle 210 in the sludge discharge pipe 23 and the upper sludge discharge hole 211. The rotary power component is used to drive the sludge discharge pipe 23 to rotate in the secondary sedimentation tank 1, which can drive the lower sludge discharge hole 214 to rotate, thereby expanding the range of sucking the lower layer of sludge settled. For example 2, please refer to Figures 1 to 11 This embodiment provides a technical solution: a reflux ratio control device for a dual reflux AOA process. The structure of this embodiment is roughly the same as that of the first embodiment, except that: It also includes a return sludge inlet water convection mixing mechanism 6, which includes a mixing box 61, a control solenoid valve 63 and a discharge trough 64. One end of the anaerobic tank sludge conveying component located in the anaerobic tank 11 and one end of the anoxic tank sludge conveying component located in the anoxic tank 13 are connected to the bottom inlets of the two mixing boxes 61 through two control solenoid valves 63 respectively. A discharge trough 64 is respectively opened in the middle of the right side of each mixing box 61, and the top of each mixing box 61 is respectively connected to the corresponding sewage transfer component 9.

[0044] The return sludge inlet convection mixing mechanism 6 also includes a box rack 62. The box rack 62 is installed on the top of the mixing box 61. The box rack 62 in the anaerobic tank 11 is connected to the left end of the anaerobic tank 11, and the box rack 62 in the anoxic tank 13 is connected to the left end of the anoxic tank 13.

[0045] Specifically, one end of the upper return pipe three 35 located in the anaerobic tank 11 is connected to the bottom of the mixing box 61 in the anaerobic tank 11 through a control solenoid valve 1 63, and one end of the lower return pipe three 45 located in the anoxic tank 13 is connected to the bottom of the mixing box 61 in the anoxic tank 13 through a control solenoid valve 1 63.

[0046] Open the control solenoid valve 1 63, and the sludge in the anaerobic tank sludge conveying component and the anoxic tank sludge conveying component enter the bottom of the two mixing boxes 61 respectively. Specifically: the anaerobic tank sludge conveying component conveys the sludge into the bottom of the mixing box 61 in the anaerobic tank, and the sewage transfer component 9 conveys the external sewage into the top of the mixing box 61 in the anaerobic tank. The external sewage is quickly mixed with the sludge at the bottom of the mixing box 61 in the anaerobic tank, and is discharged into the anaerobic tank through the discharge groove 64. The anoxic tank sludge conveying component conveys the sludge into the bottom of the mixing box 61 in the anoxic tank. The sewage transfer component 9 between the aerobic tank 12 and the anoxic tank 13 conveys the sewage in the aerobic tank 12 into the top of the mixing box 61 in the anoxic tank 13. The sewage here is quickly mixed with the sludge at the bottom of the mixing box 61 in the anoxic tank, and is discharged into the anoxic tank 13 through the discharge groove 64. This can promote the rapid mixing of the returned sludge with the sewage in the original tank, which is beneficial to improving the sewage treatment efficiency.

[0047] The return sludge water inlet convection mixing mechanism 6 also includes a semicircular baffle 65, a horizontal baffle 66, a mud hole 67 and a water hole 68. A semicircular baffle 65 is provided in the middle of the left side of the mixing box 61. The upper half of the semicircular baffle 65 is evenly provided with water holes 68, and the lower half of the semicircular baffle 65 is evenly provided with mud holes 67. The upper and lower ends of the semicircular baffle 65 are respectively fixedly connected to the left ends of the two horizontal baffles 66, and the right ends of the two horizontal baffles 66 are respectively connected to the upper and lower ends of the discharge groove 64. The semicircular baffle 65 and the two horizontal baffles 66 constitute a convection mixing bin. The position above the convection mixing bin in the mixing box 61 is the water inlet chamber, and the position below the convection mixing bin in the mixing box 61 is the mud inlet chamber.

[0048] The sludge enters the mud inlet chamber of the mixing box 61 through the control solenoid valve 63, and the sludge is dispersed into the convection mixing bin through the mud hole 67. The sewage enters the water inlet chamber of the mixing box 61 through the sewage transfer component 9, and then the sewage is dispersed into the convection mixing bin through the water hole 68. The dispersed sewage and the dispersed sludge are fully convected, quickly mixed, and mixed evenly. This process is suitable for the situation where the sewage transfer component 9 transports sewage into the mixing box 61.

[0049] For example three, please refer to Figures 1 to 11 This embodiment provides a technical solution: a reflux ratio control device for a dual reflux AOA process. The structure of this embodiment is roughly the same as that of the second embodiment, except that: It also includes a return sludge water inlet stirring mechanism 7, which includes a rotating drum 72, a counter-drive assembly, a stirring outer frame 78, a stirring inner frame 79 and a rotating shaft 710. A longitudinal rotating drum 72 is rotatably installed in the middle of the front end of each mixing box 61, and a rotating shaft 710 is rotatably connected inside the rotating drum 72. A sealing rubber ring is provided between the rotating drum 72 and the rotating shaft 710 to prevent water seepage between the rotating drum 72 and the rotating shaft 710. The rear end of the rotating drum 72 is connected to the stirring outer frame 78, and the rear end of the rotating shaft 710 is connected to the stirring inner frame 79. The stirring inner frame 79 is located on the inner side of the stirring outer frame 78, and the stirring outer frame 78 and the stirring inner frame 79 are both located in the corresponding convection mixing bin. The front end of the rotating drum 72 and the front end of the rotating shaft 710 are connected to the counter-drive assembly.

[0050] The opposite drive assembly includes a sealed bearing 2 71, a bevel gear 1 73, a bevel gear 2 74, a driving bevel gear 75, a stirring motor 76 and a motor seat 77. The left front end of the anaerobic tank 11 and the left front end of the anoxic tank 13 are respectively connected to the front end of the rotating drum 72 through the sealed bearing 2 71. The outer peripheral side of the front end of the rotating drum 72 is equipped with a bevel gear 1 73. The front end of the rotating shaft 710 extends to the outside of the front end of the rotating drum 72, and the outer peripheral side of the front end of the rotating shaft 710 is equipped with a bevel gear 2 74. The left front end of the anaerobic tank 11 and the A stirring motor 76 is installed on the front side of the left end of the anoxic tank 13 through a motor seat 77. A driving bevel gear 75 is installed on the output shaft at the top of the stirring motor 76. The driving bevel gear 75 is located between the corresponding bevel gear 1 73 and bevel gear 2 74, and the front and rear sides of the driving bevel gear 75 are respectively engaged with bevel gear 2 74 and bevel gear 1 73. The stirring motor 76 drives the driving bevel gear 75 to rotate, and drives the rotating drum 72 and the rotating shaft 710 to rotate in opposite directions through the transmission of bevel gear 1 73 and bevel gear 2 74.

[0051] The counter-driving assembly drives the drum 72 and the rotating shaft 710 to rotate in opposite directions, thereby driving the outer mixing frame 78 and the inner mixing frame 79 to rotate in opposite directions in the convection mixing chamber, which is beneficial to fully mixing the sludge and sewage in the convection mixing chamber and promotes rapid mixing of the sludge and sewage.

[0052] For example 4, please refer to Figures 1 to 11 This embodiment provides a technical solution: a reflux ratio control device for a dual reflux AOA process. The structure of this embodiment is roughly the same as that of the third embodiment, except that: The sludge conveying device 8 further includes a return sludge discharge stirring mechanism 8, which includes a bend pipe 81, a second control solenoid valve 82, a third rotary joint 83, a stirring drive assembly, a stirring vertical pipe 86, a radial pipe 87, a stirring pipe 88, and a mud outlet trough 89. One end of the anaerobic tank sludge conveying assembly in the anaerobic tank 11 and one end of the anoxic tank sludge conveying assembly in the anoxic tank 13 are respectively connected to the bottom ends of the two bend pipes 81. A second control solenoid valve 82 is respectively installed in the middle of each bend pipe 81. The top end of each bend pipe 81 is connected to the stirring vertical pipe 86 through a third rotary joint 83. The bottom end of the tube 86 and the top of each stirring vertical tube 86 are respectively connected to the stirring drive assembly, and the side of each stirring vertical tube 86 is connected to a vertical stirring tube 88 through a radial tube 87. The stirring tube 88 is provided with a mud outlet groove 89 at equal vertical distances on one side away from the stirring vertical tube 86. Each stirring vertical tube 86 is respectively provided with no less than six mud outlet grooves 89, and the upper and lower ends of the stirring tube 88 are respectively closed. Three stirring tubes 88 are arranged around the outside of each stirring vertical tube 86, and each stirring tube 88 is respectively connected to the corresponding stirring vertical tube 86 through two radial tubes 87.

[0053] The stirring drive assembly includes a longitudinal beam 84 and a stirring motor 85. Two longitudinal beams 84 are respectively installed at the top center of the anaerobic tank 11 and the top center of the anoxic tank 13. The middle parts of the two longitudinal beams 84 are rotatably connected to the top of the corresponding stirring vertical pipe 86 through bearings. The top of the stirring vertical pipe 86 is connected to the output shaft of the stirring motor 85. The stirring motor 85 is installed on the corresponding longitudinal beam 84 and is used to drive the stirring vertical pipe 86 to rotate.

[0054] When the sewage transfer assembly 9 does not transport sewage into the mixing box 61 and the sludge flows back into the mixing box 61, the control solenoid valve 1 63 is closed and the control solenoid valve 2 82 is opened. The sludge is sent into the stirring vertical pipe 86 through the elbow 81 and the rotary joint 3 83, and then sent into the stirring pipe 88 through the radial pipe 87. It is dispersed and discharged into the corresponding anaerobic tank 11 or anoxic tank 13 through the mud outlet trough 89. The stirring drive assembly drives the stirring vertical pipe 86, the radial pipe 87 and the stirring pipe 88 to rotate. The rotary joint 3 83 ensures that the rotating stirring vertical pipe 86 and the elbow 81 can still have medium conduction. The radial pipe 87 and the stirring pipe 88 are also used as stirring rods. The sludge dispersed into the tank body through the mud outlet trough 89 is fully stirred with the sewage in the tank body, thereby achieving full mixing of the sewage and the sludge.

[0055] For other examples, see Figures 1 to 11 , a sludge discharge pipe 16 and a sludge discharge solenoid valve 17 are also provided. One end of the upper layer return pipe 3 35 close to the shell 51 is connected to one end of the sludge discharge pipe 16, and the other end of the sludge discharge pipe 16 is connected to the external sludge filter press. The sludge discharge solenoid valve 17 is installed on the sludge discharge pipe 16. The sludge discharge solenoid valve 17 closes the sludge discharge pipe 16 when it is not necessary to discharge sludge through the sludge discharge pipe 16. When the sludge in the secondary sedimentation tank 1 needs to be discharged, the upper layer return pipe 3 35 is closed by the upper layer return solenoid valve 36, and the lower layer return pipe 3 45 is closed by the lower layer return solenoid valve 46. The sludge discharge solenoid valve 17 is opened, and the switching motor 57 drives the switching plate 53 and the two circular plates 54 to rotate. When the sludge diversion chamber 1 connects the upper layer return pipe 2 34 in the upper layer sludge pumping assembly with the end of the upper layer return pipe 3 35, the upper layer sludge pumping assembly extracts the sludge in the upper layer of the secondary sedimentation tank 1 and then enters the discharge through the end of the upper layer return pipe 3 35. The mud pipe 16 can discharge the sludge in the upper layer of the secondary sedimentation tank 1 and then separate the mud and water through the sludge filter press. When the sludge diversion chamber 2 connects the lower layer return pipe 2 44 in the lower layer sludge pumping assembly with the end of the upper layer return pipe 3 35, the lower layer sludge pumping assembly draws out the sludge in the lower layer of the secondary sedimentation tank 1 and enters the mud discharge pipe 16 through the end of the upper layer return pipe 3 35. The sludge in the lower layer of the secondary sedimentation tank 1 can be discharged and then separated from the mud by the sludge filter press, thereby selectively controlling the discharge of the upper and lower layers of sludge in the secondary sedimentation tank 1.

[0056] It is worth noting that the sewage pump 91, sewage flow meter 14, ultrasonic mud level meter 15, control motor 26, switching motor 57, upper mud discharge pump 33, upper reflux solenoid valve 36, lower mud discharge pump 43, lower reflux solenoid valve 46, control solenoid valve 1 63, stirring motor 76, control solenoid valve 2 82, stirring motor 85, and mud discharge solenoid valve 17 disclosed in the above embodiments are all controlled by an external PLC controller, and the control method adopts the method commonly used in the prior art. The switching motor 57 adopts a servo motor, and the control motor 26, stirring motor 85 and stirring motor 76 all adopt reduction motors.

[0057] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0058] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A reflux ratio control device for a double reflux AOA process, comprising an anaerobic tank (11), an aerobic tank (12), an anoxic tank (13) and a secondary sedimentation tank (1) which are sequentially arranged from left to right, and the anaerobic tank (11), the aerobic tank (12), the anoxic tank (13) and the secondary sedimentation tank (1) are sequentially connected in series via a sewage transfer component (9), characterized in that: Also includes: The mud discharge position control mechanism (2) comprises a mud discharge rotating pipe (23), the bottom center of the second sedimentation tank (1) is rotatably connected to the bottom end of the mud discharge rotating pipe (23), the mud discharge rotating pipe (23) is provided with a lower mud discharge hole (214) at a position located at the bottom of the second sedimentation tank (1), the mud discharge rotating pipe (23) is provided with an annular array of upper mud discharge holes (211) at a position above the lower mud discharge hole (214) in the mud discharge rotating pipe (23), and a baffle (210) is provided at a position between the upper mud discharge hole (211) and the lower mud discharge hole (214) in the mud discharge rotating pipe (23); An upper sludge return mechanism (3) has one end connected to the top of the sludge discharge transfer pipe (23), and the other end of the upper sludge return mechanism (3) extends to the front end of the water inlet in the anaerobic tank (11); One end of the lower sludge return mechanism (4) is connected to the bottom end of the sludge discharge transfer pipe (23), and the other end of the lower sludge return mechanism (4) extends to the front end of the water inlet in the anoxic tank (13).

2. The reflux ratio control device for the double reflux AOA process according to claim 1, characterized in that: The mud discharge position control mechanism (2) further comprises a mud scraping and mud discharge cover (212) and a support return pipe (213). The lower mud discharge hole (214) is connected to the two mud scraping and mud discharge covers (212) via two support return pipes (213). The two mud scraping and mud discharge covers (212) are arranged side by side on the left and right, and the bottoms of the two mud scraping and mud discharge covers (212) are in close contact with the bottom of the secondary sedimentation tank (1).

3. The reflux ratio control device for the double reflux AOA process according to claim 2, characterized in that: The sludge discharge position control mechanism (2) further comprises a conical sludge spacer sleeve (28) and a sealing rubber ring (29). The sludge discharge rotating pipe (23) is located at the bottom of the secondary sedimentation tank (1) and is sleeved with the conical sludge spacer sleeve (28). A sealing rubber ring (29) is installed between the bottom of the conical sludge spacer sleeve (28) and the bottom of the secondary sedimentation tank (1).

4. The reflux ratio control device for the double reflux AOA process according to claim 1, characterized in that: The upper sludge return mechanism (3) includes an upper sludge pumping assembly and an anaerobic tank sludge conveying assembly. The top end of the sludge discharge pipe (23) is connected to one end of the upper sludge pumping assembly, and the other end of the upper sludge pumping assembly is connected to the front end of the return mud layer switching mechanism (5). The right end of the return mud layer switching mechanism (5) is connected to one end of the anaerobic tank sludge conveying assembly, and the other end of the anaerobic tank sludge conveying assembly extends to the left end of the anaerobic tank (11).

5. The reflux ratio control device for the double reflux AOA process according to claim 4, characterized in that: The lower sludge return mechanism (4) includes a lower sludge pumping assembly and an anoxic tank sludge conveying assembly. The bottom end of the sludge discharge pipe (23) is connected to one end of the lower sludge pumping assembly, and the other end of the lower sludge pumping assembly is connected to the rear end of the return mud layer switching mechanism (5). The left end of the return mud layer switching mechanism (5) is connected to one end of the anoxic tank sludge conveying assembly, and the other end of the anoxic tank sludge conveying assembly extends to the left end of the anoxic tank (13).

6. The reflux ratio control device for the double reflux AOA process according to claim 5, characterized in that: The reflux mud layer switching mechanism (5) includes a shell (51), a circular switching groove (52), a switching plate (53), a circular plate (54), a shell cover (55) and a switching motor (57). The shell (51) is provided with a circular switching groove (52) in the middle, and the shell cover (55) is installed on the top of the shell (51). The switching motor (57) is installed in the middle of the shell cover (55). The bottom output shaft of the switching motor (57) extends into the circular switching groove (52) and is fixedly connected to the top center of the switching plate (53). The two ends of the switching plate (53) are respectively provided with arc surfaces that match the side walls of the circular switching groove (52). The upper and lower sides of the switching plate (53) are respectively provided with two circular plates (54).

7. The reflux ratio control device for the double reflux AOA process according to claim 6, characterized in that: The invention also includes a return sludge inlet water convection mixing mechanism (6), wherein the return sludge inlet water convection mixing mechanism (6) includes a mixing box (61), a control solenoid valve (63) and a discharge channel (64). One end of the anaerobic tank sludge conveying component located in the anaerobic tank (11) and one end of the anoxic tank sludge conveying component located in the anoxic tank (13) are connected to the bottom inlets of the two mixing boxes (61) through two control solenoid valves (63). A discharge channel (64) is respectively opened in the middle of the right side of each mixing box (61), and the top of each mixing box (61) is respectively connected to the corresponding sewage transfer component (9).

8. The reflux ratio control device for the double reflux AOA process according to claim 7, characterized in that: The return sludge inlet convection mixing mechanism (6) further comprises a semicircular baffle (65), a horizontal baffle (66), a mud hole (67) and a water hole (68). A semicircular baffle (65) is provided in the middle of the left side of the mixing box (61). The upper half of the semicircular baffle (65) is evenly provided with water holes (68), and the lower half of the semicircular baffle (65) is evenly provided with mud holes (67). The upper and lower ends of the semicircular baffle (65) are respectively fixedly connected to the left ends of the two horizontal baffles (66), and the right ends of the two horizontal baffles (66) are respectively connected to the upper and lower ends of the discharge trough (64). The semicircular baffle (65) and the two horizontal baffles (66) constitute a convection mixing chamber.

9. The reflux ratio control device for the double reflux AOA process according to claim 7, characterized in that: The invention also includes a return sludge inlet water stirring mechanism (7), which includes a rotating drum (72), a stirring outer frame (78), a stirring inner frame (79) and a rotating shaft (710). A longitudinal rotating drum (72) is rotatably mounted in the middle of the front end of each mixing box (61). The rotating drum (72) is rotatably connected to the rotating shaft (710). The rear end of the rotating drum (72) is connected to the stirring outer frame (78). The rear end of the rotating shaft (710) is connected to the stirring inner frame (79). The stirring inner frame (79) is located on the inner side of the stirring outer frame (78), and the stirring outer frame (78) and the stirring inner frame (79) are both located in the corresponding convection mixing chamber. The front end of the rotating drum (72) and the front end of the rotating shaft (710) are connected to the opposite driving assembly.

10. The reflux ratio control device for the double reflux AOA process according to claim 7, characterized in that: The invention also includes a return sludge discharge stirring mechanism (8), which includes a stirring vertical pipe (86). One end of the anaerobic tank sludge conveying component is located in the anaerobic tank (11), and the other end of the anoxic tank sludge conveying component is located in the anoxic tank (13), which are respectively connected to the bottom ends of the two elbows (81). A control solenoid valve 2 (82) is installed in the middle of each elbow (81). The top of each elbow (81) is connected to the bottom end of the stirring vertical pipe (86) through a rotary joint 3 (83). The top of each stirring vertical pipe (86) is connected to the stirring drive assembly. The side of each stirring vertical pipe (86) is connected to a vertical stirring pipe (88) through a radial pipe (87). The stirring pipe (88) is provided with a mud discharge trough (89) at equal vertical distances on a side away from the stirring vertical pipe (86).

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