A sedimentation basin

Abstract

This application relates to a novel sedimentation tank, specifically in the field of sludge treatment technology. The novel sedimentation tank includes a sedimentation tank with a residual sludge zone, a return sludge zone, a sorting zone, and a sludge screen. Activated sludge enters the sorting zone from the top. A first conveying component is located at the bottom of the sorting zone to transport the activated sludge from the bottom of the sorting zone to the residual sludge zone. A second conveying component is located at the top of the sorting zone to transport the activated sludge from the top of the sorting zone to the sludge screen. The sludge screen then transports the heavier activated sludge to the return sludge zone. The coordinated operation of these components allows for the screening of activated sludge discharged from the biological treatment system, removing activated sludge with poor settling properties while allowing the better settling properties to be reused. This avoids reduced wastewater treatment efficiency due to the deteriorated settling properties of the activated sludge reused in the biological treatment system.

Description

Technical Field

[0001] This application relates to the field of sludge treatment technology, and in particular to a sedimentation tank. Background Technology

[0002] Sedimentation tanks are an important component of activated sludge systems. Activated sludge discharged from the biochemical system enters the sedimentation tank for sedimentation, thereby separating the sludge from the water and concentrating the activated sludge so that it can be reused.

[0003] Currently, sedimentation tanks used in biological treatment systems mostly rely on gravity to allow activated sludge to settle naturally. The settled activated sludge is then directly reused in the biological treatment system without screening. This treatment method results in the activated sludge being of varying quality, with sludge of low density and poor settling performance mixed with sludge of high density and good settling performance. This leads to a decrease in the overall settling performance of the mixed activated sludge, thus affecting the wastewater treatment efficiency. Furthermore, the return flow rate when reusing it in the biological treatment system is large, resulting in high energy consumption. Summary of the Invention

[0004] To address the problem that existing technologies for treating activated sludge result in inconsistent quality of the sludge reused in biological systems, with low-density sludge and poor settling properties being mixed with high-density sludge and good settling properties, leading to poor overall settling performance of the mixed activated sludge and impacting wastewater treatment efficiency, as well as high return flow and energy consumption when reused in biological systems, this application provides a sedimentation tank.

[0005] The sedimentation tank provided in this application adopts the following technical solution:

[0006] A sedimentation tank includes a sedimentation tank with a residual sludge zone, a return sludge zone, a sorting zone, and a sludge screen. Activated sludge enters the sorting zone through the top. A first conveying member is provided at the bottom of the sorting zone to convey the activated sludge at the bottom of the sorting zone to the residual sludge zone. A second conveying member is provided at the top of the sorting zone to convey the activated sludge at the top of the sorting zone to the sludge screen. The sludge screen conveys heavy activated sludge to the return sludge zone.

[0007] By adopting the above technical solution, the activated sludge discharged from the biochemical system enters the sorting zone through the top of the sorting zone. At this time, the more fluid activated sludge will fall to the bottom of the sorting zone first, and the first conveyor will transport this part of the more fluid activated sludge to the residual sludge zone. The more fluid activated sludge has a low density and light weight, so its settling performance is poor. This part of the activated sludge is stored in the residual sludge zone for subsequent discharge. The less fluid activated sludge will accumulate at the top of the sorting zone, and the second conveyor will transport this part of the activated sludge to the sludge screener. The sludge screener will then screen this part of the activated sludge, and the sludge screener will transport the heavy sludge in this part of the activated sludge to the return sludge zone. The activated sludge that falls into the return sludge zone has a high density and heavy weight, so it has good settling performance. This part of the activated sludge is stored in the return sludge zone for subsequent reuse. The coordinated operation of the various components in the above process allows for the screening of activated sludge discharged from the biological system. Activated sludge with poor settling performance is discharged, while activated sludge with good settling performance can be reused. This avoids a decrease in the efficiency of wastewater treatment due to the deterioration of the settling performance of the activated sludge reused in the biological system. In addition, by screening the activated sludge for precise reuse, the return flow to the biological system can be reduced, thereby reducing energy consumption.

[0008] Optionally, the sedimentation tank is provided with a fermentation sludge zone, and the sludge screener includes a hydrocyclone separator. The second conveying member is used to convey the activated sludge at the top of the sorting zone to the inlet of the hydrocyclone separator. The hydrocyclone separator has an underflow outlet and an overflow outlet. The underflow outlet faces the return sludge zone and is used to discharge heavy activated sludge, while the overflow outlet faces the fermentation sludge zone and is used to discharge light activated sludge.

[0009] By adopting the above technical solution, the second conveyor transports the activated sludge from the top of the sorting zone to the hydrocyclone separator. The hydrocyclone separator sorts the activated sludge, discharging the heavier activated sludge through the underflow outlet to the return sludge zone, while the lighter activated sludge is discharged through the overflow outlet to the fermentation sludge zone. The fermentation sludge zone ferments this lighter activated sludge. The activated sludge undergoes anaerobic fermentation in the fermentation tank, which promotes the decomposition of organic matter and produces volatile fatty acids, forming a suitable carbon source ratio and phosphorus source ratio. This is beneficial for the absorption and storage of phosphorus in the activated sludge, thereby enhancing the phosphorus removal effect of the activated sludge. In addition, the VFAS produced by the decomposition of organic matter can provide a carbon source, reducing the demand for external carbon sources. After the fermented activated sludge is applied to wastewater treatment operations, the amount of sludge generated during wastewater treatment can be reduced, thereby reducing wastewater treatment costs and the pressure of sludge treatment.

[0010] Optionally, the fermentation sludge zone is provided with a first connection port communicating with the remaining sludge zone, and a first control gate is provided at the first connection port to control the opening and closing of the first connection port; the fermentation sludge zone is provided with a second connection port communicating with the return sludge zone, and a second control gate is provided at the second connection port to control the opening and closing of the second connection port.

[0011] By adopting the above technical solution, when the amount of activated sludge to be treated in the sedimentation tank is large and the capacity of the residual sludge zone to receive activated sludge is insufficient, the first connecting port can be opened by controlling the first control gate to connect the fermentation sludge zone and the residual sludge zone. At this time, the volume of the residual sludge zone is expanded, and more activated sludge can be received. Similarly, when the capacity of the return sludge zone to receive activated sludge is insufficient, the second connecting port can be opened by controlling the second control gate to connect the fermentation sludge zone and the return sludge zone. At this time, the volume of the return sludge zone is expanded, and more activated sludge can be received. This makes the sedimentation tank more flexible in its application.

[0012] Optionally, an overflow seat is provided at the top of the sludge return zone, a drainage trough is provided on the overflow seat, and a water inlet for sludge water to enter is provided on the overflow seat, the water inlet being connected to the drainage trough; a drainage zone is provided in the sedimentation tank, and a drainage pipe connected to the drainage zone is provided in the drainage trough; the sludge screener transports heavy activated sludge to below the overflow seat through the pipeline.

[0013] By adopting the above technical solution, heavy activated sludge is transported to the return sludge zone through a sludge screen. The heavy activated sludge undergoes re-sedimentation in the return sludge zone, and the sludge water that settles out flows to the overflow seat at the top of the return sludge zone. The sludge water enters the drainage trough through the inlet, and then enters the drainage pipe through the drainage trough. Subsequently, it is discharged to the drainage zone through the drainage pipe. This part of the sludge water is collected in the drainage zone for reuse. The heavy activated sludge at the bottom of the return sludge zone will have better settling performance after re-sedimentation.

[0014] Optionally, a three-phase separator for filtering sludge water is provided in the sludge return zone, and the three-phase separator is located below the overflow seat.

[0015] By adopting the above technical solution, when the sludge water from the sedimentation of heavy activated sludge flows, it carries some of the activated sludge along with it. The three-phase separator plays a preliminary filtration role in the return sludge zone. The sludge water can flow through the three-phase separator to the overflow seat and then enter the drainage zone through the drainage trough. The activated sludge carried in the sludge water will be intercepted by the three-phase separator, thereby preventing the reusable heavy activated sludge from being discharged and not being effectively utilized. At the same time, it prevents some activated sludge from flowing with the sludge water to the overflow seat, which would cause blockage of the inlet and affect the discharge of the sludge water.

[0016] Optionally, a filtration system is provided in the residual sludge zone, and the sludge water in the residual sludge zone enters the drainage zone through the filtration system.

[0017] By adopting the above technical solution, the highly fluid activated sludge is transported to the waste sludge zone and re-sedimented there. The sludge water that settles out will enter the drainage zone through a filtration system, where it will be collected for reuse. After re-sedimentation, the highly fluid activated sludge in the waste sludge zone will have a smaller volume, reducing the workload and pressure required for its discharge and thus lowering the energy consumption.

[0018] Optionally, a dosing pipe is rotatably installed in the residual sludge zone, the dosing pipe is provided with a dispersing blade, the dispersing blade has a dispersing port communicating with the dosing pipe, and a driving component is provided in the residual sludge zone to drive the dosing pipe to rotate.

[0019] By adopting the above technical solution, when the highly fluid activated sludge is transported to the waste sludge zone, a precipitant can be delivered into the dosing pipe during the filtration process. The driving component simultaneously drives the dosing pipe to rotate, which in turn drives the dispersing blades to rotate. The precipitant is then sprayed out through the dispersing port, where it reacts with the waste sludge in the waste sludge zone. Some of the activated sludge and impurities carried in the waste sludge will fall off under the action of the precipitant, thus preventing excessive activated sludge and impurities from clogging the filtration system and placing a heavy burden on its operation.

[0020] Optionally, a conveying pipe is connected within the sorting zone, through which activated sludge enters the sorting zone; a cleaning pipe is connected to the conveying pipe, which is connected to the drainage zone, and a water pump and a control valve for controlling the opening and closing of the cleaning pipe are installed on the cleaning pipe.

[0021] By adopting the above technical solution, the conveying pipe is used to connect the biological system. The activated sludge discharged from the biological system enters the sorting zone through the conveying pipe and is then transported to the residual sludge zone and the return sludge zone respectively. After a single treatment of the activated sludge is completed, the cleaning pipe can be opened by controlling the control valve. The cleaning pipe is connected to the conveying pipe, and water from the drainage zone is discharged into the conveying pipe by the water pump to clean the conveying pipe and remove the residual activated sludge inside the conveying pipe. This prevents the activated sludge from accumulating and solidifying in the conveying pipe, which would cause blockage and increase the burden on subsequent cleaning operations.

[0022] Optionally, the top of the reflux sludge zone is provided with a slot for the end of the overflow seat to be inserted, the end of the overflow seat away from the slot is detachably connected to the drain pipe, and the drainage zone is provided with an installation hole for the drain pipe to pass through.

[0023] By adopting the above technical solution, when installing the overflow seat, one end of the overflow seat is inserted into the slot, and the drain pipe is connected to the other end of the overflow seat. The end of the drain pipe passes through the mounting hole and communicates with the drainage area. The drain pipe supports the overflow seat. With the cooperation of the drain pipe and the slot, the installation of the overflow seat is completed. The cooperation of the various components in the above process allows for the quick installation and disassembly of the overflow seat. When the activated sludge volume in the return sludge zone is large, the overflow seat can be removed, and the sludge water in the return sludge zone can enter the drainage zone through the mounting hole, thereby quickly discharging the sludge water.

[0024] Optionally, a filter plate is provided in the drainage trough, and a chamber for filling filter media is formed between the filter plate and the wall of the drainage trough.

[0025] By adopting the above technical solution, the muddy water enters the drainage trough, is filtered by the filter medium, and then enters the drainage area. The filter medium performs preliminary treatment on the muddy water, and some of the activated sludge and impurities carried in the muddy water will be intercepted by the filter medium and filter plate. With this setting, on the one hand, blockage of the drainage area can be avoided, and on the other hand, the muddy water can be preliminarily treated, which is conducive to the subsequent reuse of muddy water and reduces the difficulty of subsequent reprocessing of muddy water.

[0026] In summary, this application includes at least one of the following beneficial technical effects:

[0027] 1. Activated sludge discharged from the biological treatment system can be screened to remove activated sludge with poor settling performance, while activated sludge with good settling performance can be reused. This avoids the reduced efficiency of wastewater treatment caused by the deterioration of the settling performance of the activated sludge reused in the biological treatment system. In addition, by screening the activated sludge for precise reuse, the return flow to the biological treatment system can be reduced, thereby reducing energy consumption.

[0028] 2. Heavy activated sludge is transported to the return sludge zone through a sludge screen. The heavy activated sludge undergoes re-sedimentation in the return sludge zone. The sludge water that settles out flows to the overflow seat at the top of the return sludge zone. The sludge water enters the drainage trough through the inlet, and then enters the drainage pipe through the drainage trough. Subsequently, it is discharged to the drainage zone through the drainage pipe. This part of the sludge water is collected in the drainage zone for reuse. The heavy activated sludge at the bottom of the return sludge zone will have better settling performance after re-sedimentation.

[0029] 3. The more fluid activated sludge is transported to the waste sludge zone and undergoes re-sedimentation. The sludge water that settles out will enter the drainage zone through a filtration system, where it will be collected for reuse. After re-sedimentation, the more fluid activated sludge in the waste sludge zone will have a smaller volume, reducing the workload and pressure required for its discharge and thus lowering the energy consumption. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of a sedimentation tank in Embodiment 1 of this application;

[0031] Figure 2 This is a top view of Embodiment 1 of this application;

[0032] Figure 3 This is a cross-sectional view of Embodiment 1 of this application from a first perspective, mainly used to show the structure of the conveying pipe;

[0033] Figure 4 This is a cross-sectional view of Embodiment 1 of this application from a second perspective, mainly used to show the structure of the excess sludge zone and the return sludge zone;

[0034] Figure 5 This is a cross-sectional view of Embodiment 1 of this application from a third perspective, mainly used to show the structure of the reflux sludge zone, the first fermentation zone, and the second fermentation zone;

[0035] Figure 6 This is a supplementary description of Embodiment 1 of this application;

[0036] Figure 7 This is a schematic diagram of the overall structure of a sedimentation tank according to Embodiment 2 of this application;

[0037] Figure 8 yes Figure 6 Enlarged view of section A;

[0038] Figure 9 yes Figure 6Enlarged view of section B;

[0039] Figure 10 yes Figure 6 Enlarged view of section C.

[0040] Explanation of reference numerals in the attached drawings: 1. Sedimentation tank; 2. Excess sludge zone; 3. Return sludge zone; 4. Separation zone; 5. Sludge screen; 51. Hydrocyclone separator; 6. First conveying component; 61. Excess sludge conveying pipe; 7. Second conveying component; 71. Return sludge conveying pipe; 8. Fermentation sludge zone; 81. First fermentation zone; 82. Second fermentation zone; 83. Third fermentation zone; 84. Fourth fermentation zone; 9. First connecting port; 10. First control gate; 11. Second connecting port. 12. Second control gate; 13. Overflow seat; 14. Three-phase separator; 15. Inclined plate; 16. Dosing pipe; 17. Dispersing blade; 18. Dispersing port; 19. Drive motor; 20. Driving bevel gear; 21. Driven bevel gear; 22. Drainage area; 23. Drainage trough; 24. Inlet; 25. Drainage pipe; 26. Conveying pipe; 27. First branch pipe; 28. Second branch pipe; 29. ​​Cleaning pipe; 30. Slot; 31. Mounting hole; 32. Filter plate. Detailed Implementation

[0041] The following is in conjunction with the appendix Figure 1-9 This application will be described in further detail.

[0042] Example 1

[0043] Embodiment 1 of this application discloses a sedimentation tank. (Refer to...) Figure 1 and Figure 2 The sedimentation tank includes a sedimentation tank 1, which is equipped with a residual sludge zone 2, a return sludge zone 3, a sorting zone 4, and a sludge screen 5. Activated sludge enters the sorting zone 4 through the top. A first conveying member 6 is provided at the bottom of the sorting zone 4 to transport the activated sludge at the bottom of the sorting zone 4 to the residual sludge zone 2. A second conveying member 7 is provided at the top of the sorting zone 4 to transport the activated sludge at the top of the sorting zone 4 to the sludge screen 5. The sludge screen 5 is used to transport the heavy activated sludge to the return sludge zone 3.

[0044] Reference Figure 3 and Figure 4The sorting zone 4 is connected to a conveying pipe 26, which is used to connect with the biological system. The activated sludge discharged from the biological system enters the sorting zone 4 through the conveying pipe 26. The first conveying component 6 includes a residual sludge conveying pipe 61 located at the bottom of the sorting zone 4. The bottom of the sorting zone 4 and the bottom of the residual sludge zone 2 are connected to each other through the residual sludge conveying pipe 61. The second conveying component 7 includes a return sludge conveying pipe 71 connected to the top of the sorting zone 4. A sludge pump (not shown in the figure) is installed on the return sludge conveying pipe 71 for pumping activated sludge. The sludge screener 5 includes a hydrocyclone separator 51. The return sludge conveying pipe 71 is connected to the inlet of the hydrocyclone separator 51. The hydrocyclone separator 51 has an underflow port facing the return sludge zone 3 and is used to discharge heavy activated sludge.

[0045] Reference Figure 4 and Figure 5 In the return sludge zone 3, a three-phase separator 14 and an overflow seat 13 are arranged sequentially from bottom to top. The underflow port of the cyclone separator 51 is connected to the area below the three-phase separator 14 in the return sludge zone 3 through a pipeline. Multiple overflow seats 13 are provided. Each overflow seat 13 is provided with a drainage trough 23 and an inlet 24 connected to the drainage trough 23. The inlet 24 is connected to the return sludge zone 3 and is used to allow sludge and water to enter. A back-shaped drainage zone 22 is provided in the sedimentation tank 1. A drainage pipe 25 connected to the drainage zone 22 is connected in the drainage trough 23.

[0046] Heavy activated sludge is transported to the return sludge zone 3 through the sludge screen 5. The heavy activated sludge undergoes re-sedimentation in the return sludge zone 3, and the sludge water that settles overflows upwards. The sludge water undergoes preliminary filtration through the three-phase separator 14, where the activated sludge is intercepted. The sludge water can flow through the three-phase separator 14 to the overflow seat 13, and then enters the drainage trough 23 through the inlet 24. It then enters the drainage pipe 25 through the drainage trough 23 and is subsequently discharged to the drainage zone 22 through the drainage pipe 25. This portion of sludge water is collected in the drainage zone 22 for reuse. The heavy activated sludge at the bottom of the return sludge zone 3 will have better settling performance after re-sedimentation.

[0047] Reference Figure 3A filtration system is installed in the residual sludge zone 2. The filtration system includes a three-phase separator 14, multiple inclined plates 15, and multiple overflow seats 13, arranged sequentially from bottom to top within the residual sludge zone 2. Adjacent inclined plates 15 form channels for the flow of sludge-water mixture. Activated sludge with good flowability is transported to the residual sludge zone 2 and undergoes re-sedimentation. The sludge-water mixture that settles overflows upwards. It undergoes preliminary filtration by the three-phase separator 14, and then flows to the inclined plates 15 for secondary filtration. With the combined action of the three-phase separator 14 and the inclined plates 15, the activated sludge... The sludge will be intercepted; the sludge water after passing through the inclined plate 15 will flow to the overflow seat 13 at the top of the return sludge zone 3. The sludge water will enter the drainage trough 23 through the inlet 24, and then enter the drainage pipe 25 through the drainage trough 23. Subsequently, it will be discharged to the drainage zone 22 through the drainage pipe 25. This part of the sludge water will be collected in the drainage zone 22 for reuse. The activated sludge with good fluidity in the remaining sludge zone 2 will have a smaller volume after re-sedimentation. The workload of discharging this part of the activated sludge will be reduced, the pressure of discharging the activated sludge will be reduced, and the energy consumption of discharging the activated sludge will be reduced.

[0048] In this embodiment, a three-phase separator 14 and an overflow seat 13 are provided in the return sludge zone 3. These two components work together to screen and filter the sludge-water sediment that settles in the return sludge zone 3. (Refer to...) Figure 6 In other embodiments, in order to further improve the screening and filtration effect of mud and water, an inclined plate 15 can be added to the return sludge zone 3. The three-phase separator 14, the inclined plate 15 and the overflow seat 13 are arranged from bottom to top in the return sludge zone 3. The mud and water are initially filtered by the three-phase separator 14, the inclined plate 15 performs secondary filtration, and the overflow seat 13 performs a third filtration.

[0049] Reference Figure 1 and Figure 2 The sedimentation tank 1 is equipped with a fermentation sludge zone 8. The hydrocyclone separator 51 has an overflow port facing the fermentation sludge zone 8 and is used to discharge light activated sludge. The conveying pipe 26 is connected to a first branch pipe 27 and a second branch pipe 28. The first branch pipe 27 extends into the sorting zone 4 and is connected to the sorting zone 4. The second branch pipe 28 extends into the fermentation sludge zone 8 and is connected to the fermentation sludge zone 8. Both the first branch pipe 27 and the second branch pipe 28 are equipped with control valves to control the opening and closing of the corresponding pipes.

[0050] The activated sludge discharged from the biochemical system is transported to the conveying pipe 26. Part of it enters the sorting zone 4 through the first branch pipe 27, while the other part enters the fermentation sludge zone 8 through the second branch pipe 28. After the return sludge conveying pipe 71 transports the activated sludge to the hydrocyclone separator 51, the heavy activated sludge is discharged into the return sludge zone 3 through the underflow outlet, while the light activated sludge is discharged into the fermentation sludge zone 8 through the overflow outlet. The fermentation sludge zone 8 ferments this portion of the light activated sludge. Anaerobic fermentation takes place in the fermentation tank, which promotes the decomposition of organic matter and produces volatile fatty acids, forming a suitable carbon source ratio and phosphorus source ratio. This is beneficial for the absorption and storage of phosphorus in activated sludge, thereby enhancing the phosphorus removal effect of activated sludge. In addition, the VFAS produced by the decomposition of organic matter can provide a carbon source, reducing the need for external carbon sources. After the fermented activated sludge is applied to wastewater treatment operations, the amount of sludge generated during wastewater treatment can be reduced, thereby reducing wastewater treatment costs and sludge management pressure.

[0051] Reference Figure 1 and Figure 2 The fermentation sludge zone 8 includes a first fermentation zone 81, a second fermentation zone 82, a third fermentation zone 83, and a fourth fermentation zone 84 connected in sequence. Connecting ports and control valves for closing the corresponding connecting ports are provided between the first fermentation zone 81 and the second fermentation zone 82, between the second fermentation zone 82 and the third fermentation zone 83, and between the third fermentation zone 83 and the fourth fermentation zone 84. A second branch pipe 28 extends into and connects to the first fermentation zone 81, with its overflow outlet facing the first fermentation zone 81. The fermentation sludge zone 8 as a whole includes multiple different fermentation zones, each used to treat activated sludge differently, thereby further improving the practicality and applicability of the sedimentation tank 1. The sedimentation tank 1 can meet different activated sludge treatment needs.

[0052] Reference Figure 3The fourth fermentation zone 84 is provided with a first connection port 9 that communicates with the remaining sludge zone 2. A first control gate 10 is provided at the first connection port 9 to control the opening and closing of the first connection port 9. The first fermentation zone 81 is provided with a second connection port 11 that communicates with the return sludge zone 3. A second control gate 12 is provided at the second connection port 11 to control the opening and closing of the second connection port 11. When the amount of activated sludge to be treated in sedimentation tank 1 is large and the capacity of the residual sludge zone 2 to receive activated sludge is insufficient, the first connecting port 9 can be opened by controlling the first control gate 10, so that the fourth fermentation zone 84 is connected to the residual sludge zone 2. At this time, the volume of the residual sludge zone 2 is expanded, and more activated sludge can be received. Similarly, when the capacity of the return sludge zone 3 to receive activated sludge is insufficient, the second connecting port 11 can be opened by controlling the second control gate 12, so that the first fermentation zone 81 is connected to the return sludge zone 3. At this time, the volume of the return sludge zone 3 is expanded, and more activated sludge can be received, thus making the sedimentation tank 1 more flexible in its use.

[0053] The implementation principle of a sedimentation tank in Embodiment 1 of this application is as follows: Activated sludge discharged through the biochemical system enters the sorting zone 4 through the top of the sorting zone 4. At this time, the more fluid activated sludge will first fall to the bottom of the sorting zone 4, and the residual sludge conveying pipe 61 will transport this part of the more fluid activated sludge to the residual sludge zone 2. The more fluid activated sludge has a low density and light weight, so its settling performance is poor. This part of the activated sludge is stored in the residual sludge zone 2 for subsequent discharge. The less fluid activated sludge will accumulate at the top of the sorting zone 4, and the return sludge conveying pipe 71 will transport this part of the activated sludge to the sludge screener 5. The sludge screener 5 will then screen this part of the activated sludge. The sludge screener 5 will transport the heavy sludge in this part of the activated sludge to the return sludge zone 3. The activated sludge falling into the return sludge zone 3 has a high density and heavy weight, so it has good settling performance. This part of the activated sludge is stored in the return sludge zone 3 for subsequent reuse. The coordinated operation of the various components in the above process allows for the screening of activated sludge discharged from the biological system. Activated sludge with poor settling performance is discharged, while activated sludge with good settling performance can be reused. This avoids a decrease in the efficiency of wastewater treatment due to the deterioration of the settling performance of the activated sludge reused in the biological system. In addition, by screening the activated sludge for precise reuse, the return flow to the biological system can be reduced, thereby reducing energy consumption.

[0054] Example 2

[0055] The difference between Example 2 and Example 1 is that: (Refer to...) Figure 7A filtration system is installed in the residual sludge zone 2. The filtration system includes a three-phase separator 14 and multiple overflow seats 13 arranged sequentially from bottom to top in the residual sludge zone 2. A dosing pipe 16 is rotatably installed in the residual sludge zone 2. A driving component for driving the dosing pipe 16 to rotate is provided on the residual sludge zone 2.

[0056] Reference Figure 7 and Figure 8 The top of the residual sludge zone 2 is equipped with an installation plate. The driving components include a drive motor 19 mounted on the installation plate. The output shaft of the drive motor 19 is coaxially fixedly connected to a driving bevel gear 20. The outer wall of the dosing pipe 16 is coaxially fixedly connected to a driven bevel gear 21, which meshes with the driving bevel gear 20. A dispersing blade 17 is installed at the bottom of the dosing pipe 16. The dispersing blade 17 is located below the three-phase separator 14. A dispersing port 18 communicating with the dosing pipe 16 is opened on the dispersing blade 17.

[0057] Reference Figure 7 A cleaning pipe 29 is connected to the conveying pipe 26, and the cleaning pipe 29 is connected to the drainage area 22. The cleaning pipe 29 is equipped with a water pump and a control valve for controlling the opening and closing of the cleaning pipe 29. The conveying pipe 26 is used to connect to the biological system. The activated sludge discharged from the biological system enters the sorting area 4 through the conveying pipe 26 and is then transported to the residual sludge area 2 and the return sludge area 3 respectively. After a single treatment of the activated sludge is completed, the cleaning pipe 29 can be opened by controlling the control valve. The cleaning pipe 29 is connected to the conveying pipe 26, and the water pump discharges water from the drainage area 22 into the conveying pipe 26 to clean the conveying pipe 26 and remove the residual activated sludge in the conveying pipe 26. This prevents the activated sludge from accumulating and solidifying in the conveying pipe 26, which would cause blockage and increase the burden on subsequent cleaning operations.

[0058] Reference Figure 7 and Figure 9 Both the top of the return sludge zone 3 and the top of the residual sludge zone 2 are provided with slots 30 for the corresponding overflow seats 13 to be inserted. The end of each overflow seat 13 away from the corresponding slot 30 is threaded to the drain pipe 25. The drainage zone 22 is provided with an installation hole 31 for the drain pipe 25 to pass through. When installing the overflow seat 13, one end of the overflow seat 13 is inserted into the slot 30, and the drain pipe 25 is connected to the other end of the overflow seat 13. The end of the drain pipe 25 passes through the installation hole 31 and communicates with the drainage zone 22. The drain pipe 25 thus supports the overflow seat 13. With the cooperation of the drain pipe 25 and the slot 30, the installation of the overflow seat 13 is completed. This method allows for quick installation and removal of the overflow seat 13. When the activated sludge volume in the return sludge zone 3 is large, the overflow seat 13 can be removed, and the mud and water in the return sludge zone 3 can enter the drainage zone 22 through the installation hole 31, thereby quickly draining the mud and water.

[0059] Reference Figure 7 and Figure 10 A filter plate 32 is installed inside the drainage trough, and a chamber for filling the filter medium is formed between the filter plate 32 and the wall of the drainage trough. The muddy water enters the drainage trough, is filtered by the filter medium, and then enters the drainage zone 22. The filter medium performs preliminary treatment on the muddy water, and some of the activated sludge and impurities carried in the muddy water will be intercepted by the filter medium and the filter plate 32. This setting can avoid clogging of the drainage zone 22 on the one hand, and perform preliminary treatment on the muddy water on the other hand, which is conducive to the subsequent reuse of the muddy water and reduces the difficulty of subsequent reprocessing of the muddy water.

[0060] The implementation principle of Example 2 is as follows: When the fluid activated sludge is transported to the residual sludge zone 2, the sludge water is filtered through the three-phase separator 14 and the overflow seat 13. The precipitant is delivered into the dosing pipe 16. The rotation of the output shaft of the drive motor 19 drives the active bevel gear 20 to rotate. The active bevel gear 20 further drives the driven bevel gear 21 to rotate, which in turn drives the dosing pipe 16 to rotate. The dosing pipe 16 thereby drives the dispersing leaf 17 to rotate. The precipitant is sprayed out through the dispersing port 18. The precipitant reacts with the sludge water in the residual sludge zone 2. Some of the activated sludge and impurities carried in the sludge water will fall off under the action of the precipitant. This avoids the excessive activated sludge and impurities from clogging the filtration system when passing through it, and also avoids putting a heavy burden on the filtration operation of the filtration system.

[0061] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A sedimentation tank, characterized in that: The system includes a sedimentation tank (1), which is equipped with a residual sludge zone (2), a return sludge zone (3), a sorting zone (4), and a sludge screen (5). Activated sludge enters the sorting zone (4) through the top of the sorting zone (4). A first conveying member (6) is provided at the bottom of the sorting zone (4) to convey the activated sludge at the bottom of the sorting zone (4) to the residual sludge zone (2). A second conveying member (7) is provided at the top of the sorting zone (4) to convey the activated sludge at the top of the sorting zone (4) to the sludge screen (5). The sludge screen (5) is used to convey heavy activated sludge to the return sludge zone (3). The sedimentation tank (1) is provided with a fermentation sludge zone (8). The sludge screener (5) includes a hydrocyclone separator (51). The second conveying member (7) is used to convey the activated sludge at the top of the sorting zone (4) to the inlet of the hydrocyclone separator (51). The hydrocyclone separator (51) has an underflow port and an overflow port. The underflow port faces the return sludge zone (3) and is used to discharge heavy activated sludge. The overflow port faces the fermentation sludge zone (8) and is used to discharge light activated sludge. The sorting zone (4) is connected to a conveying pipe (26), and the conveying pipe (26) is connected to a first branch pipe (27) and a second branch pipe (28). The first branch pipe (27) extends into the sorting zone (4) and is connected to the sorting zone (4). The second branch pipe (28) extends into the fermentation sludge zone (8) and is connected to the fermentation sludge zone (8). Part of the activated sludge discharged from the biochemical system enters the sorting zone (4) through the first branch pipe (27), and another part enters the fermentation sludge zone (8) through the second branch pipe (28). The fermentation sludge zone (8) includes a first fermentation zone (81), a second fermentation zone (82), a third fermentation zone (83), and a fourth fermentation zone (84) connected in sequence. A communication port and a control valve for closing the corresponding communication port are provided between the first fermentation zone (81) and the second fermentation zone (82), between the second fermentation zone (82) and the third fermentation zone (83), and between the third fermentation zone (83) and the fourth fermentation zone (84). The second branch pipe (28) extends into the first fermentation zone (81) and is connected to the first fermentation zone (81). The overflow port faces the first fermentation zone (81). The fourth fermentation zone (84) is provided with a first connection port (9) that communicates with the remaining sludge zone (2). A first control gate (10) for controlling the opening and closing of the first connection port (9) is provided at the first connection port (9). The first fermentation zone (81) is provided with a second connection port (11) that communicates with the return sludge zone (3). A second control gate (12) for controlling the opening and closing of the second connection port (11) is provided at the second connection port (11).

2. A sedimentation tank according to claim 1, characterized in that: The top of the sludge return zone (3) is provided with an overflow seat (13), and a drainage trough (23) is provided on the overflow seat (13). An inlet (24) for sludge water to enter is provided on the overflow seat (13), and the inlet (24) is connected to the drainage trough (23). A drainage zone (22) is provided in the sedimentation tank (1), and a drainage pipe (25) connected to the drainage zone (22) is provided in the drainage trough (23). The sludge screener (5) transports heavy activated sludge to the bottom of the overflow seat (13) through the pipeline.

3. A sedimentation tank according to claim 2, characterized in that: The return sludge zone (3) is equipped with a three-phase separator (14) for filtering sludge water, and the three-phase separator (14) is located below the overflow seat (13).

4. A sedimentation tank according to claim 2, characterized in that: A filtration system is installed in the residual sludge zone (2), and the mud and water in the residual sludge zone (2) enter the drainage zone (22) through the filtration system.

5. A sedimentation tank according to claim 4, characterized in that: A dosing pipe (16) is rotatably installed in the residual sludge zone (2). A dispersing leaf (17) is provided on the dosing pipe (16). A dispersing port (18) communicating with the dosing pipe (16) is opened on the dispersing leaf (17). A driving component for driving the dosing pipe (16) to rotate is provided on the residual sludge zone (2).

6. A sedimentation tank according to claim 2, characterized in that: The sorting zone (4) is connected to a conveying pipe (26), through which activated sludge enters the sorting zone (4); a cleaning pipe (29) is connected to the conveying pipe (26), which is connected to the drainage zone (22), and a water pump and a control valve for controlling the opening and closing of the cleaning pipe (29) are provided on the cleaning pipe (29).

7. A sedimentation tank according to claim 2, characterized in that: The top of the return sludge zone (3) is provided with a slot (30) for the end of the overflow seat (13) to be inserted. The end of the overflow seat (13) away from the slot (30) is detachably connected to the drain pipe (25). The drainage zone (22) is provided with an installation hole (31) for the drain pipe (25) to pass through.

8. A sedimentation tank according to claim 2, characterized in that: A filter plate (32) is provided in the drainage trough, and a chamber for filling the filter medium is formed between the filter plate (32) and the wall of the drainage trough (23).

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