Variable-density self-circulation aerobic granular sludge treatment device

Abstract

The utility model relates to the technical field of sewage treatment, and provides a variable-density self-circulation aerobic granular sludge treatment device which comprises an anoxic tank, a micro-aerobic tank, an aerobic tank and a sedimentation tank which are arranged along a water body flowing path, and a water body accelerating device which is arranged in the anoxic tank; the inlet end of the backflow main pipe is provided with a sludge backflow branch pipe extending into the sedimentation tank and / or a nitrification liquid backflow branch pipe extending into the aerobic tank, and the outlet end of the backflow main pipe is provided with a first pipe section extending into the anoxic tank and located in the throat pipe; the outlet end of the reflux header pipe is also provided with a second pipe section which extends to the anoxic tank and is positioned outside the throat pipe; one end of the ventilation pipe extends into the second pipe section, the other end of the ventilation pipe is suitable for being connected with a gas source, and gas is introduced into the second pipe section through the ventilation pipe. According to the device, double drainage is carried out by utilizing the negative pressure effect generated by water inlet jet flow and the gas stripping effect generated by ventilation of the ventilation pipe, so that nitrification liquid and / or sludge flow back to the anoxic tank, and energy conservation and environmental protection are facilitated.

Description

Technical Field

[0001] The utility model relates to the technical field of sewage treatment, in particular to an aerobic granular sludge treatment device with variable density and self-circulation. Background Art

[0002] The existing aerobic reaction devices mainly include an anoxic zone, an aerobic zone, and a sedimentation zone arranged in sequence along the flow path of sewage. After the raw sewage enters the anoxic zone, it is diluted and mixed with the microorganisms inside for anoxic reaction. Then the sewage enters the aerobic zone for aerobic reaction to further remove pollutants in the sewage. After that, the sewage enters the sedimentation zone for sedimentation separation. There is a large amount of nitrifying liquid in the downstream aerobic zone and a large amount of sludge in the sedimentation zone. In the prior art, in order to improve the treatment effect on water bodies, generally a pump body is used in cooperation with pipelines for the reflux of nitrifying liquid or sludge. However, such a design is not conducive to energy conservation and environmental protection and will increase the burden of system maintenance. Summary of the Utility Model

[0003] Therefore, the technical problem to be solved by the utility model is that the traditional aerobic reaction device uses a pump body in cooperation with pipelines for the reflux of nitrifying liquid or sludge. However, such a design is not conducive to energy conservation and environmental protection and will increase the burden of system maintenance. Thus, an aerobic granular sludge treatment device with variable density and self-circulation is provided.

[0004] To solve the above technical problem, the technical solution of the utility model is as follows:

[0005] The utility model provides an aerobic granular sludge treatment device with variable density and self-circulation, including: an anoxic tank, a micro-aerobic tank, an aerobic tank, and a sedimentation tank arranged along the water flow path. Aeration devices are arranged in both the micro-aerobic tank and the aerobic tank, and the aeration volume in the micro-aerobic tank is less than that in the aerobic tank; a water body acceleration device arranged in the anoxic tank, including a throat pipe and at least one-stage spray pipe. The throat pipe covers the top of the spray pipe, and the external water body enters the throat pipe after being accelerated by the spray pipe, and then the water body is released from the top of the throat pipe into the anoxic tank; a reflux main pipe. The inlet end of the reflux main pipe is provided with a sludge reflux branch pipe extending into the sedimentation tank and / or a nitrifying liquid reflux branch pipe extending into the aerobic tank. The outlet end of the reflux main pipe is provided with a first pipe section extending into the anoxic tank and located inside the throat pipe. The first pipe section uses the negative pressure in the throat pipe to introduce sludge and / or nitrifying liquid into the throat pipe; the outlet end of the reflux main pipe is also provided with a second pipe section extending into the anoxic tank and located outside the throat pipe; a ventilation pipe, one end of which extends into the second pipe section, and the other end is suitable for being connected to a gas source. The ventilation pipe introduces gas into the second pipe section, and uses the air-lift effect to introduce sludge and / or nitrifying liquid into the anoxic tank; a sludge discharge pipe, one end of which extends inward to the bottom of the sedimentation tank, and the other end extends outward to the outside of the sedimentation tank.

[0006] Furthermore, a sludge hopper is arranged in the sedimentation tank. The sludge return branch pipe extends into the bottom of the sludge hopper, and the pipe orifice of the sludge return branch pipe is arranged downward.

[0007] Furthermore, the variable-density self-circulating aerobic granular sludge treatment device further includes an aerobic influent diversion channel arranged between the anoxic tank and the micro-aerobic tank. The water body in the anoxic tank and part of the water body in the micro-aerobic tank enter the aerobic influent diversion channel, are mixed and then enter the micro-aerobic tank.

[0008] Furthermore, the variable-density self-circulating aerobic granular sludge treatment device further includes an aerobic sludge recovery channel arranged between the micro-aerobic tank and the aerobic tank. Part of the water body in the micro-aerobic tank enters the aerobic sludge recovery channel, and part of the water body in the aerobic tank enters the aerobic sludge recovery channel. The water bodies from the micro-aerobic tank and the aerobic tank are mixed in the aerobic sludge recovery channel, and then part of the water body flows back into the micro-aerobic tank, and the other part of the water body enters the aerobic tank.

[0009] Furthermore, the variable-density self-circulating aerobic granular sludge treatment device further includes a degassing channel arranged between the aerobic tank and the sedimentation tank. The water body in the aerobic tank is degassed in the degassing channel, and then part of the water body flows back into the aerobic tank, and the other part of the water body enters the sedimentation tank. The nitrification liquid return branch pipe is located in the degassing channel.

[0010] Furthermore, the pipe orifice of the nitrification liquid return branch pipe is arranged downward and is located in the lower half area of the degassing channel.

[0011] Furthermore, the variable-density self-circulating aerobic granular sludge treatment device further includes a water distribution pipe, one end of which is communicated with the degassing channel and the other end of which is communicated with the sedimentation tank. The pipe section of the water distribution pipe located in the sedimentation tank is a plurality of pipe bodies arranged parallel to the bottom of the sedimentation tank, and a plurality of water distribution holes are arranged on the pipe wall of each pipe body.

[0012] Further, the aeration device includes an aerator and an accelerating member; the aerator is arranged at the bottoms of the micro-aerobic tank and the aerobic tank, and the aerator is used to provide the gas required for the aerobic reaction; the accelerating member includes a premixing hood and a speed maintaining member; the premixing hood is arranged at the air outlet end of the aerator, and the space between the premixing hood and the aerator forms a first premixing zone; a gap is left between the premixing hood and the aerator to form a first water return port, and the first water return port communicates the internal and external spaces of the first premixing zone; wherein, the flow area of the release port of the premixing hood is smaller than the flow area of the water inlet of the premixing hood, so as to increase the pressure in the first premixing zone under the aeration state; one end of the speed maintaining member is connected to the release port of the premixing hood, and the other end extends in a direction away from the premixing hood.

[0013] Further, the variable-density self-circulating aerobic granular sludge treatment device further includes a partition plate; the partition plate is arranged in the lower half areas of both the micro-aerobic tank and the aerobic tank, and the partition plate divides the lower half areas of the aerobic tank and the micro-aerobic tank into a plurality of aeration zones, and the aeration device is arranged in the aeration zones; the space between two adjacent aeration zones forms an internal reflux channel, and a notch communicating the aeration zone and the internal reflux channel is left at the bottom of the partition plate, and the water flow direction in the internal reflux channel is opposite to that in the aeration zone; a flow guiding cone is arranged at the bottom of the internal reflux channel to guide the water in the internal reflux channel to flow back into the aeration zone.

[0014] Further, a sludge filter layer is formed in the sedimentation tank, the lower layer of the sludge filter layer is a nitrification filter layer, and the upper layer of the sludge filter layer is a denitrification filter layer; while the sludge filter layer filters the passing water body, the nitrification filter layer is used to remove ammonia nitrogen in the water body, and the denitrification filter layer is used to remove total nitrogen and COD in the water body.

[0015] Further, along the water flow path in the anoxic tank, there are a mixing zone, an anoxic diversion channel and an upflow anoxic zone in sequence; both the spray pipe and the throat pipe are located in the mixing zone, and a second water return port is left between the spray pipe and the throat pipe, and a part of the water body in the mixing zone flows back into the throat pipe through the second water return port; another part of the water body in the mixing zone flows out from the top and enters the anoxic diversion channel, the water body flows downward to the bottom in the anoxic diversion channel and then enters the upflow anoxic zone, and the water body in the upflow anoxic zone flows upward to the top and then enters the aerobic water inlet diversion channel; the second pipe section is located in the anoxic diversion channel.

[0016] Furthermore, the variable-density self-circulating aerobic granular sludge treatment device further includes an anoxic reflux pipe, one end of which extends into the throat pipe and the other end is located in the upflow anoxic zone; the nozzle of the anoxic reflux pipe faces upward and extends into the upper half of the upflow anoxic zone, so that the anaerobic sewage in the upflow anoxic zone can flow back to the mixing zone.

[0017] Furthermore, the anoxic tank, micro-aerobic tank, aerobic tank and sedimentation tank are integrated in a single tank body, and different regions divided in the tank body form the anoxic tank, micro-aerobic tank, aerobic tank and sedimentation tank; or one or more of the anoxic tank, micro-aerobic tank, aerobic tank and sedimentation tank are each composed of a separate tank body.

[0018] Furthermore, the variable-density self-circulating aerobic granular sludge treatment device further includes a lifting agitator, which is arranged in the mixing zone and is used to accelerate the rise of the water body in the throat pipe.

[0019] The technical solution of the present invention has the following advantages:

[0020] The variable-density self-circulating aerobic granular sludge treatment device provided by the present invention utilizes the negative pressure effect generated by the inlet water jet and the air-lift effect generated by the ventilation of the air pipe for double drainage, so that the nitrification liquid and / or sludge can flow back to the anoxic tank. Compared with using a pump body and pipelines to carry out the reflux of the nitrification liquid and / or sludge, it is beneficial to energy conservation and environmental protection and will not increase the burden of system maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 It is a top view of the variable-density self-circulating aerobic granular sludge treatment device in the embodiment of the present invention;

[0023] Figure 2 For Figure 1 It is a cross-sectional view along the A-A direction in

[0024] Figure 3 It is a partially enlarged schematic view of the local structure of the aerobic tank in the variable-density self-circulating aerobic granular sludge treatment device in the embodiment of the present invention;

[0025] Figure 4 For Figure 1 It is a cross-sectional view along the B-B direction in

[0026] Figure 5 It is an enlarged schematic diagram of the water distribution pipe in the variable-density self-circulating aerobic granular sludge treatment device in the embodiment of the present utility model;

[0027] Figure 6 It is a schematic diagram of the aeration device in an embodiment of the present utility model;

[0028] Figure 7 It is a schematic diagram of the aeration device in another embodiment of the present utility model;

[0029] Figure 8 It is a schematic diagram of the aeration device in another embodiment of the present utility model;

[0030] Figure 9 It is a schematic diagram of the aeration device in another embodiment of the present utility model;

[0031] Figure 10 It is a layout schematic diagram of the aerator in an embodiment of the present utility model; Figure 11 It is a schematic diagram of the lifting stirrer in the variable-density self-circulating sludge granulation device in an embodiment of the present utility model;

[0032] Figure 12 It is a schematic diagram of the lifting stirrer in the variable-density self-circulating sludge granulation device in another embodiment of the present utility model;

[0033] Figure 13 It is a schematic diagram of the lifting stirrer in the variable-density self-circulating sludge granulation device in another embodiment of the present utility model;

[0034] Figure 14 It is a schematic diagram of the lifting stirrer in the variable-density self-circulating sludge granulation device in another embodiment of the present utility model;

[0035] [[ID=3८]] Figure 15 It is a schematic diagram of the lifting stirrer in the variable-density self-circulating sludge granulation device in another embodiment of the present utility model;

[0036] Figure 16 It is a schematic diagram of the lifting stirrer in the variable-density self-circulating sludge granulation device in another embodiment of the present utility model;

[0037] Figure 17 It is a schematic diagram of the lifting stirrer in the variable-density self-circulating sludge granulation device in another embodiment of the present utility model.

[0038] Explanation of reference numerals:

[0039] 1. Anoxic tank; 2. Micro-aerobic tank; 3. Aerobic tank; 4. Sedimentation tank; 5. Main return pipe; 6. Aerobic influent diversion channel; 7. Aerobic sludge recovery channel; 8. Degassing channel; 9. Mixing zone; 10. Anoxic diversion channel; 11. Upflow anoxic zone; 12. Sludge hopper; 13. Sludge return branch pipe; 14. Water distribution pipe; 15. Anoxic return pipe; 16. Throat pipe; 17. Spray pipe; 18. Nitrification liquid return branch pipe; 19. First pipe section; 20. Second pipe section; 21. Vent pipe; 22. Aerator; 23. Aeration zone; 24. Internal return channel; 25. Inlet chamber; 26. Sludge filter layer; 27. Inclined tube separation device; 28. Outlet trough; 29. Sludge discharge pipe; 30. First water return port; 31. Flow guiding cone; 32. Partition board; 33. First premixing zone; 34. Speed maintaining part; 35. Premixing hood; 36. Second water return port; 37. Denitrification filter layer; 38. Nitrification filter layer; 39. Water distribution hole; 40. Rectifying hood; 41. Baffle; 42. Second premixing zone; 43. Diverging port; 44. Tooth-shaped port; 45. Lift agitator. Detailed implementation manners

[0040] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0041] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present utility model. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0042] In the description of the present utility model, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0043] In addition, the technical features involved in different embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0044] As Figure 1 , Figure 2 shown, the present utility model provides a variable density self-circulating aerobic granular sludge treatment device, including: an anoxic tank 1, a micro-aerobic tank 2, an aerobic tank 3, and a sedimentation tank 4 arranged along the water flow path; for example, the anoxic tank 1, the micro-aerobic tank 2, the aerobic tank 3, and the sedimentation tank 4 can be integrated into one tank body, and different regions divided in the tank body form the anoxic tank 1, the micro-aerobic tank 2, the aerobic tank 3, and the sedimentation tank 4. Or, one or more of the anoxic tank 1, the micro-aerobic tank 2, the aerobic tank 3, and the sedimentation tank 4 are each composed of a separate tank body. For example, the anoxic tank 1 is composed of a separate tank body, and the micro-aerobic tank 2, the aerobic tank 3, and the sedimentation tank 4 are integrated into another tank body; for another example, the anoxic tank 1, the micro-aerobic tank 2, the aerobic tank 3, and the sedimentation tank 4 are each composed of a separate tank body.

[0045] Among them, in some scenarios, there can be more than one anoxic tank 1, micro-aerobic tank 2, aerobic tank 3, and sedimentation tank 4, which can be multiple-to-multiple or one-to-multiple. For example, in some scenarios, there can be one anoxic tank 1 corresponding to multiple micro-aerobic tanks 2, aerobic tanks 3, and sedimentation tanks 4, etc. Moreover, as long as the upstream and downstream relationship of the anoxic tank 1, the micro-aerobic tank 2, the aerobic tank 3, and the sedimentation tank 4 remains unchanged, the positional relationship of the anoxic tank 1, the micro-aerobic tank 2, the aerobic tank 3, and the sedimentation tank 4 can be designed as needed. For example, from left to right, the anoxic tank 1, the micro-aerobic tank 2, the aerobic tank 3, and the sedimentation tank 4 can be arranged in sequence.

[0046] Among them, the tank bodies of the anoxic tank 1, the micro-aerobic tank 2, the aerobic tank 3, and the sedimentation tank 4 can be made of steel structure or concrete structure, and the cross-sectional shape of each tank body can be circular, rectangular, or other polygons, etc.

[0047] To more clearly reflect the inventive concept of the present application, in the following embodiments, the anoxic tank 1, the micro-aerobic tank 2, the aerobic tank 3, and the sedimentation tank 4 are taken as an example of being in the same tank body, and in the tank body, the anoxic tank 1, the micro-aerobic tank 2, the aerobic tank 3, and the sedimentation tank 4 are arranged in sequence along the first direction (left-right direction).

[0048] A water body acceleration device is arranged in the anoxic tank 1 and includes a throat pipe 16 and at least one stage of nozzle 17, that is, the nozzle 17 can be arranged in one stage or multiple stages according to the acceleration requirement of the water body. The throat pipe 16 covers the top of the nozzle 17, and the external water body enters the throat pipe 16 after being accelerated by the nozzle 17, and then the water body is released from the top of the throat pipe 16 into the anoxic tank 1.

[0049] Among them, when the amount of water to be treated is large, multiple water body acceleration devices can be arranged in the anoxic tank 1 at the same time, and the multiple water body acceleration devices are filled with water at the same time to increase the water inflow.

[0050] A return main pipe 5, a sludge return branch pipe 13 extending into the sedimentation tank 4 and / or a nitrification liquid return branch pipe 18 extending into the aerobic tank 3 are arranged at the inlet end of the return main pipe 5, and a first pipe section 19 extending into the anoxic tank 1 and located in the throat pipe 16 is arranged at the outlet end of the return main pipe 5. The first pipe section 19 uses the negative pressure in the throat pipe 16 to introduce sludge and / or nitrification liquid into the throat pipe 16; for example, there may be two first pipe sections 19, one of the first pipe sections 19 extends to a position close to the bottom of the throat pipe 16, and the other first pipe section 19 extends to a position close to the middle of the throat pipe 16. A second pipe section 20 extending into the anoxic tank 1 and located outside the throat pipe 16 is also arranged at the outlet end of the return main pipe 5.

[0051] An air vent pipe 21, one end of which extends into the second pipe section 20, and the other end is adapted to be connected to a gas source. The air vent pipe 21 introduces gas into the second pipe section 20, and uses the air-lift effect to introduce sludge and / or nitrification liquid into the anoxic tank 1. For example, the air inlet of the air vent pipe 21 is located at the top of itself, the air inlet of the air vent pipe 21 extends outside the anoxic tank 1 and is connected to an air pump or other gas source device, the air outlet of the air vent pipe 21 is located at the bottom end of its pipe body, the gas is released at the bottom of the pipe, a concentration difference is generated between the outlet end and the inlet end of the return main pipe 5, and then the fluid at the inlet end of the return main pipe 5 is drained to the outlet end for release. For example, the nitrification liquid return branch pipe 18 and the sludge return branch pipe 13 can be arranged at the same time, or only one of them can be arranged.

[0052] The variable-density self-circulation aerobic granular sludge treatment device provided by the utility model uses the negative pressure generated by the water inlet jet flow and the air-lift effect generated by the ventilation of the air vent pipe 21 for double drainage, so that the nitrification liquid and / or sludge are returned to the anoxic tank 1. Compared with using a pump body and a pipeline to return the nitrification liquid and / or sludge, it is beneficial to energy conservation and environmental protection and will not increase the burden of system maintenance.

[0053] Such as Figure 4As shown, usually, under the action of sludge reflux, its own gravity, and the influent pushing flow, a sludge filter layer 26 will be formed in the sedimentation tank 4. The lower layer of the sludge filter layer 26 is a nitrification filter layer 38, and the upper layer of the sludge filter layer 26 is a denitrification filter layer 37. While the sludge filter layer 26 filters the suspended substances in the passing water body, the nitrification filter layer 38 is used to remove ammonia nitrogen in the water body, and the denitrification filter layer 37 is used to remove total nitrogen and COD (Chemical Oxygen Demand) in the water body. Among them, the variable-density self-circulating aerobic granular sludge treatment device further includes a sludge hopper 12. For example, the sludge hopper 12 can be arranged at the central position of the sedimentation tank 4, and the micro-sludge filter layer 26 is on both sides or around the sludge hopper 12. The opening of the sludge hopper 12 faces upward, and the opening position of the sludge hopper 12 can be flush with the upper denitrification filter layer 37 to return the sludge of the denitrification filter layer 37. The nozzle of the sludge return branch pipe 13 extends to the bottom of the sludge hopper 12, and the returned sludge is used for denitrification reaction in the anoxic tank 1 to remove COD and total nitrogen in the water body.

[0054] Among them, the variable-density self-circulating aerobic granular sludge treatment device further includes an aerobic influent diversion channel 6, which is arranged between the anoxic tank 1 and the micro-aerobic tank 2. Among them, an inlet is arranged on the channel wall near the top in the aerobic influent diversion channel 6. Part of the inlets communicate the aerobic influent diversion channel 6 with the anoxic tank 1, and part of the inlets communicate the micro-aerobic tank 2 with the aerobic influent diversion channel 6. An outlet is arranged on the channel wall near the bottom in the aerobic influent diversion channel 6, and this outlet communicates the aerobic influent diversion channel 6 with the micro-aerobic tank 2. During use, the water body in the anoxic tank 1 and part of the water body in the micro-aerobic tank 2 enter the aerobic influent diversion channel 6, are mixed and then enter the micro-aerobic tank 2.

[0055] Among them, the variable-density self-circulating aerobic granular sludge treatment device further includes an aerobic sludge recovery channel 7, which is arranged between the micro-aerobic tank 2 and the aerobic tank 3. Among them, an inlet is arranged on the channel wall near the top in the aerobic sludge recovery channel 7. Part of the inlets communicate the micro-aerobic tank 2 with the aerobic sludge recovery channel 7, and part of the inlets communicate the aerobic sludge recovery channel 7 with the aerobic tank 3, so that part of the water body in the micro-aerobic tank 2 enters the aerobic sludge recovery channel 7. At the same time, part of the water body in the aerobic tank 3 can also enter the aerobic sludge recovery channel 7. An outlet is arranged on the channel wall near the bottom in the aerobic sludge recovery channel 7, and this outlet communicates the aerobic sludge recovery channel 7 with the aerobic tank 3. The water bodies from the micro-aerobic tank 2 and the aerobic tank 3 are mixed in the aerobic sludge recovery channel 7, and then part of the water body returns to the micro-aerobic tank 2, and the other part of the water body enters the aerobic tank 3.

[0056] Among them, the variable-density self-circulating aerobic granular sludge treatment device further includes a degassing channel 8; the degassing channel 8 is arranged between the aerobic tank 3 and the sedimentation tank 4, and a water inlet is arranged on the channel wall near the top in the degassing channel 8, and the water body in the aerobic tank 3 enters the degassing channel 8 through this water inlet; moreover, since the water inlet level of the degassing channel 8 is at the top of the aerobic tank 3, the sludge can sink in the aerobic tank 3 by relying on the height. After the water body in the aerobic tank 3 is degassed in the degassing channel 8, a part of the water body flows back into the aerobic tank 3, and another part of the water body enters the sedimentation tank 4; the nitrification liquid reflux branch pipe 18 is located in the degassing channel 8. For example, the pipe orifice of the nitrification liquid reflux branch pipe 18 can face downward and be located in the lower half area of the degassing channel 8. For example, an opening is arranged on the channel wall of the bottom of the degassing channel 8 close to the aerobic tank 3 for the degassing channel 8 to return water to the aerobic tank 3. A guide plate inclined towards this opening can be arranged at the bottom of the degassing channel 8 to guide the water body to flow back into the aerobic tank 3 preferentially.

[0057] As Figure 2 , Figure 5 As shown, the space on the side of the guide plate facing away from the opening serves as the water inlet chamber 25 of the sedimentation tank 4, one end of the water distribution pipe 14 is communicated with this water inlet chamber 25, and the other end extends into the sedimentation tank 4. The pipe section of the water distribution pipe 14 located in the sedimentation tank 4 is a plurality of pipe bodies arranged parallel to the bottom of the sedimentation tank 4, the pipe bodies are located outside the sludge hopper 12, and a plurality of water distribution holes 39 are arranged on the pipe wall of each pipe body. For example, when the water distribution holes 39 spray water, the water can be distributed obliquely downward at an angle of 45°.

[0058] As Figure 3 As shown, among them, the aeration device includes an aerator 22 and an accelerating member; the aerator 22 is arranged at the bottoms of the micro-aerobic tank 2 and the aerobic tank 3, and the aerator 22 is used to provide the gas required for the aerobic reaction; the accelerating member includes a premixing hood 35 and a speed maintaining member 34; the premixing hood 35 covers the gas outlet end of the aerator 22, and the space between the premixing hood 35 and the aerator 22 forms a first premixing zone 33; a gap is left between the premixing hood 35 and the aerator 22 to form a first water return port 30, and the first water return port 30 communicates the space inside and outside the first premixing zone 33; among them, the flow area of the release port of the premixing hood 35 is smaller than the flow area of the water inlet of the premixing hood 35 to increase the pressure in the first premixing zone 33 in the aeration state; one end of the speed maintaining member 34 is connected to the release port of the premixing hood 35, and the other end extends in a direction away from the premixing hood 35. Among them, the number or power of the aerators 22 in the micro-aerobic tank 2 can be controlled so that the aeration volume in the micro-aerobic tank 2 is less than the aeration volume in the aerobic tank 3. With such a setting, the micro-aerobic tank 2 is equivalent to a pre-aerobic section. Since the system is a plug-flow treatment, anoxic and aerobic reactions occur in the micro-aerobic tank 2 to perform a pretreatment on the pollutants, reducing the load of the subsequent aerobic tank 3 and improving the treatment effect of the subsequent section.

[0059] For example, the premixing hood 35 can be a frustum-shaped structure with both upper and lower ends open, the large-mouth end at the bottom and the small-mouth end at the top, and the small-mouth end is used as the release port. For another example, the premixing hood 35 can also be a prism-shaped structure with both upper and lower ends open, the large-mouth end at the bottom and the small-mouth end at the top, and the small-mouth end is used as the release port. Among them, the premixing hood 35 can be welded to the side wall of the aerobic tank 3 by arranging connecting rods on the side wall; it can also be installed as an integral structure with the air pipe support of the aerator 22 and fixed on the air pipe support of the aerator 22. Among them, the speed-keeping part 34 can be a round pipe or a square pipe, which can be selected according to needs. Because the speed-keeping part 34 increases the height of the release port of the premixing hood 35, the flow rate of the gas-liquid mixture outside the premixing hood 35 is relatively low, and the speed difference with the gas-liquid mixture in the first premixing zone 33 is relatively large, so the pressure difference is large. Compared with the case without the speed-keeping part 34, the speed difference between the two is even larger, so the drainage effect is better.

[0060] During use, the aerator 22 releases air in the first premixing zone 33. Due to the rapid rise of the bubbles, it will drive the water outside the first premixing zone 33 to enter the first premixing zone 33 through the first water return port 30. In addition, the constriction of the release port directly above the premixing hood 35 causes the pressure in the first premixing zone 33 to rise, enabling the bubbles to further mix with the water flowing back through the first water return port 30. And due to the increase in pressure, the effect of gas dissolving in water will be better. The gas-liquid mixture after mixing is ejected from the release port and rises to the aerobic area outside the first premixing zone 33. The speed-keeping part 34 can extend the time of high-speed water movement and delay the release. With such a setting, when the aeration device is in use, by means of reflux, mixing, and pressurized gas dissolution, the dissolved oxygen concentration can be increased, and the efficiency is higher and more energy-saving under the same aeration conditions.

[0061] Among them, the variable-density self-circulating aerobic granular sludge treatment device further includes a partition plate 32; partition plates 32 are arranged in the lower half of both the micro-aerobic tank 2 and the aerobic tank 3. The partition plate 32 divides the lower half of the aerobic tank 3 and the micro-aerobic tank 2 into multiple aeration zones 23, and the aeration device is arranged in the aeration zones 23; the space between two adjacent aeration zones 23 forms an internal reflux channel 24. There is a notch at the bottom of the partition plate 32 to connect the aeration zone 23 and the internal reflux channel 24, and the water flow direction in the internal reflux channel 24 is opposite to that in the aeration zone 23. During use, the gas action of the aerator 22 can be utilized to accelerate water diversion, so that more water flows back, thereby accelerating the circulating reflux between the internal reflux channel 24 and the aeration zone 23, and enabling the water to be quickly mixed. Moreover, under the aeration action, the water flow in the aeration zone 23 rises rapidly, and the heavy sludge will flow downward through the internal reflux channel 24 and then participate in the upward process of aeration again, making the formation efficiency of sludge particles faster. In addition, through this high-speed up-and-down movement and gas-water scrubbing, the granular sludge is more stable and the sphericity ratio of the granular sludge is better. The

[0062] A guide cone 31 is provided at the bottom of the inner return channel 24 to guide the water in the inner return channel 24 back to the aeration zone 23. This arrangement can prevent mud accumulation in the inner return channel 24 and is conducive to the guidance of air lift drainage.

[0063] like Figure 6 As shown, in one embodiment, the release port of the premix cover 35 may not be provided with the speed retaining member 34 .

[0064] like Figure 7 As shown, the aeration device further includes a fairing 40 positioned over the discharge port of the premixing hood 35. The end of the fairing 40 distal to the premixing hood 35 is sealed, and the inner diameter of the fairing 40 gradually decreases as it moves away from the premixing hood 35. The space between the fairing 40 and the premixing hood 35 forms a second premixing zone 42. A gap is left between the fairing 40 and the premixing hood 35 to form a diversion port 43, which connects the second premixing zone 42 with the space outside the second premixing zone 42. The fairing 40 can be welded to the sidewall of the aeration zone 23 by connecting rods provided on the sidewall. For example, the fairing 40 can have a conical structure with the top of the cone at the top. For another example, the premixing hood 35 can have a prismatic structure with the smaller top surface at the top. The shape of the fairing 40 is compatible with the shape of the premixing hood 35. For example, if the premixing hood 35 is a truncated cone, the fairing 40 can have a conical structure. For example, when the premixing cover 35 is a prism-shaped structure, the fairing 40 can be a prismatic structure. During use, the gas-water mixture in the first premixing zone 33 enters the second premixing zone 42 through the release port of the premixing cover 35. The gas-water mixture in the second premixing zone 42 flows out through the diversion port 43 and is divided into a first branch and a second branch. The gas-water mixture in the first branch moves toward the first return water port 30, thereby forming a circulation, and the gas-water mixture in the second branch flows over the fairing 40 toward the downstream. Moreover, since the sidewalls of the fairing 40 are inclined surfaces, a slope can be formed. A portion of the gas-water mixture will slide down the slope (because the acceleration of the edge fluid forms a flow velocity difference) and counter-mix with the rapidly rising gas-water mixture in the second branch, thereby improving the mixing effect. With this arrangement, there is backflow, mixing, and pressurized dissolved gas in the aeration zone 23, which increases the concentration of dissolved oxygen. Under the same aeration conditions, the efficiency is improved and energy conservation is more significant.

[0065] like Figure 8 As shown, in one embodiment, the fairing 40 may also be provided on the end of the speed-retaining component 34 away from the premixing cover 35 .

[0066] like Figure 10As shown in the figure, several toothed openings 44 can be provided at the edge of the mouth of the fairing 40, and the several toothed openings 44 are distributed along the circumference of the fairing 40. With such a setting, there are two advantages: one is that the mixing effect can be increased through the toothed openings 44. Because the flow rates in the concave and convex areas of the toothed openings 44 are different, the disturbance mixing effect can be increased; the other is the function of cutting bubbles, which can turn large bubbles into smaller bubbles, increasing the contact area with water and increasing dissolved oxygen. In addition, the gas-water mixture has horizontal and downward return momentum, which can further increase the mixing effect. Moreover, the downward component of the gas-water mixture will increase the mixing extension, lengthen the effective contact time, and prevent it from directly rising to the liquid surface. With such a setting, the extension is increased, the reaction time is prolonged, the concentration of dissolved oxygen is increased, and under the same aeration conditions, the efficiency is improved and it is more energy-saving.

[0067] As Figure 9 shown in the figure, the aeration device further includes a baffle 41, which is arranged inside the fairing 40, and the plate surface of the baffle 41 faces the outlet of the speed-keeping member 34. During use, the gas-water mixture released from the outlet at the top of the speed-keeping member 34 impacts the baffle 41 and then diffuses around. With such a setting, it can prevent gas accumulation at the top of the fairing 40, causing bubbles to gather, and enable the gas to be smoothly released into the water, improving the gas-water mixing effect.

[0068] Among them, along the water flow path in the anoxic tank 1 are a mixing zone 9, an anoxic diversion channel 10, and an upflow anoxic zone 11 in sequence; both the spray pipe 17 and the throat pipe 16 are located in the mixing zone 9, and a second water return port 36 is left between the spray pipe 17 and the throat pipe 16. A part of the water body in the mixing zone 9 flows back into the throat pipe 16 through the second water return port 36;

[0069] Both the spray pipe 17 and the throat pipe 16 are located in the mixing zone 9, and a second water return port 36 is left between the spray pipe 17 and the throat pipe 16. A part of the water body in the mixing zone 9 flows back into the throat pipe 16 through the second water return port 36. Among them, a water inlet is provided on the channel wall near the top of the anoxic diversion channel, and the water body in the mixing zone 9 enters the anoxic diversion channel through this water inlet. A reverse V-shaped channel is provided at a position near the bottom of the anoxic diversion channel, so that the water body in the anoxic reverse flow enters the upflow anoxic zone through this reverse V-shaped channel. With such a setting, the water body in the upflow anoxic zone 11 flows upward, which can make the microorganisms rise in suspension through hydraulic force, facilitating the acquisition of nutrients by the microorganisms and making the reaction more complete.

[0070] Among them, the second pipe section 20 is located in the anoxic diversion channel. The top of the second pipe section 20 is bent and extends into the upper half of the mixing zone 9. One end of the ventilation pipe 21 extends into the anoxic diversion channel and is inserted into the second pipe section 20, and the other end extends to the outside of the anoxic diversion channel and can be connected to a gas source.

[0071] Among them, the variable-density self-circulating aerobic granular sludge treatment device further includes an anoxic reflux pipe 15, one end of which extends into the throat pipe 16 and the other end is located in the up-flow anoxic zone 11; the nozzle of the anoxic reflux pipe 15 faces upward and extends into the upper half of the up-flow anoxic zone 11, so that the anaerobic sewage in the up-flow anoxic zone 11 can flow back to the mixing zone 9. For example, the nozzle of the anoxic reflux pipe 15 can also be of a funnel-shaped structure to increase the water inflow during reflux. With such a setting, the water volume in the mixing zone 9 increases, the upward flow velocity increases, and the sludge is suspended. Moreover, by refluxing a part of the anoxic sludge, the sludge in the mixing zone 9 can be supplemented and inoculated.

[0072] During use, before the raw water enters the mixing zone 9, it is accelerated by the water sprayed by the nozzle and the fused reflux water, and a circulating mixing reaction that is upward in the middle and downward around is carried out in the mixing zone 9. In this section, there is anoxic sewage reflux from the up-flow anoxic zone 11, sludge reflux from the sedimentation tank 4, and nitrification liquid reflux from the degassing channel 8. After these refluxed waters are mixed with the raw water, a denitrification reaction is carried out to remove COD and total nitrogen.

[0073] Among them, a lamella separation device 27 can also be arranged in the sedimentation tank 4 to further precipitate and separate the escaped small suspended matters. An effluent trough 28 is arranged downstream of the lamella separation device 27, and the effluent trough 28 is externally connected to an outlet pipe. After the clear water enters the effluent trough 28, it is discharged from the outlet pipe. A sludge discharge pipe 29 can also be arranged at the bottom of the sedimentation tank 4. One end of the sludge discharge pipe 29 extends inward into the bottom of the sedimentation tank 4, and the other end extends outward to the outside of the sedimentation tank 4 for discharging the sludge in the sedimentation tank 4.

[0074] As Figure 11 shown, among them, in one embodiment, the variable-density self-circulating aerobic granular sludge treatment device further includes a lifting stirrer 45. The base of the lifting stirrer 45 can be installed on the top of the mixing zone 9, and the connecting rod and the spiral fan blade of the lifting stirrer 45 both extend into the throat pipe 16. During use, the water body in the throat pipe 16 can be promoted to rise by the lifting stirrer 45. For example, the lifting stirrer 45 can adopt variable-frequency control so that the rotation speed of the spiral fan blade can be adjusted. At this time, the upward flow velocity of the water body can also be adjusted, and then the amount of water body reflux will also change with the change of the speed. Among them, the lifting stirrer 45 can be used alone or in cooperation with spraying and air-lifting.

[0075] As Figure 12 shown, among them, in one embodiment, the bottom of the mixing zone 9 adopts pressure water inlet. After the water inlet, there is jet acceleration, and there are multiple acceleration devices in the rising section for drainage; in addition to the jet pipe acceleration, there is also a lifting stirrer 45 in the upper part for upstream assistance, and the speed of the spiral fan blade can change the drainage strength and flow rate. There are two layers or several layers of drainage in the throat pipe 16, and the water bodies that need to be refluxed in the anoxic zone, aerobic zone and sedimentation zone can be refluxed and mixed.

[0076] As Figure 13 As shown in the figure, in one embodiment, the bottom of the mixing zone 9 uses gravity inlet water. Since the upward flow rate of the lifting agitator 45 is increased, the reflux required during the upward process can be drained through variable-diameter acceleration. All the upward flow rates are channel spiral fan blades, and the number of layers of the spiral fan blades can be calculated to be two or more layers; the speed of the spiral fan blades can change the drainage strength and flow rate. The throat 16 has two or several layers of drainage, and can mix the water bodies that need to be refluxed in the anoxic zone, aerobic zone and sedimentation zone.

[0077] As Figure 14 shown in the figure, in one embodiment, the bottom of the mixing zone 9 uses gravity inlet water. The inlet water first enters an annular water distribution chamber, and there are annular gaps at the bottom of the chamber for uniform water distribution; after water distribution, it enters the central upward zone, and the lifting agitator 45 is used for upward lifting. The speed of the spiral fan blades can change the drainage strength and flow rate; the point that needs reflux during the lifting process is reduced in diameter and accelerated, and then connected to the reflux pipe. The throat 16 needs to have two or several layers of drainage and is reduced in diameter, and can mix the reflux that needs to be refluxed in the anoxic zone, aerobic zone and sedimentation zone.

[0078] As Figure 15 shown in the figure, in one embodiment, the bottom of the mixing zone 9 uses gravity inlet water. The inlet water first enters an annular water distribution chamber, and there are annular gaps at the bottom of the chamber for uniform water distribution; after water distribution, it enters the central upward zone, and the lifting agitator 45 is used for upward lifting. The speed of the spiral fan blades can change the drainage strength and flow rate; the point that needs reflux during the lifting process is reduced in diameter and accelerated, and then connected to the reflux pipe. The impellers are mainly arranged in the upper area.

[0079] As Figure 16 shown in the figure, in one embodiment, the bottom of the mixing zone 9 uses gravity inlet water, and the spiral fan blades are arranged with unequal diameters.

[0080] As Figure 17 shown in the figure, in one embodiment, the bottom of the mixing zone 9 uses gravity inlet water. After rebounding from the bottom plate, it rises due to the lifting action of the lifting agitator 45; after water distribution, it enters the central upward zone, and the lifting agitator 45 is used for upward lifting. The speed of the spiral fan blades can change the drainage strength and flow rate; then it is connected to the reflux pipe. The spiral fan blades are arranged in an independent hopper, and the hopper is connected to the reflux pipe, so that the water bodies that need to be refluxed in areas such as the anoxic zone, aerobic zone and sedimentation zone return to the central mixing zone.

[0081] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or variations derived therefrom still fall within the protection scope of the creation of the present utility model.

Claims

1. An aerobic granular sludge treatment device with variable density and self-circulation, characterized in that Comprising: An anoxic tank (1), a micro-aerobic tank (2), an aerobic tank (3), and a sedimentation tank (4) arranged along the water flow path. Aeration devices are provided in both the micro-aerobic tank (2) and the aerobic tank (3), and the aeration volume in the micro-aerobic tank (2) is less than that in the aerobic tank (3); A water body acceleration device, arranged in the anoxic tank (1), comprising a throat pipe (16) and at least one stage of nozzle (17). The throat pipe (16) covers the top of the nozzle (17). The external water body is accelerated by the nozzle (17) and then enters the throat pipe (16), and the water body is then released from the top of the throat pipe (16) into the anoxic tank (1); A reflux main pipe (5), the inlet end of the reflux main pipe (5) is provided with a sludge reflux branch pipe (13) extending into the sedimentation tank (4) and / or a nitrification liquid reflux branch pipe (18) extending into the aerobic tank (3). The outlet end of the reflux main pipe (5) is provided with a first pipe section (19) extending into the anoxic tank (1) and located inside the throat pipe (16). The first pipe section (19) uses the negative pressure in the throat pipe (16) to introduce sludge and / or nitrification liquid into the throat pipe (16); The outlet end of the reflux main pipe (5) is further provided with a second pipe section (20) extending into the anoxic tank (1) and located outside the throat pipe (16); An air vent pipe (21), one end extends into the second pipe section (20), and the other end is adapted to be connected to a gas source. The air vent pipe (21) introduces gas into the second pipe section (20), and uses the air-lift effect to introduce sludge and / or nitrification liquid into the anoxic tank (1).

2. The variable-density self-circulating aerobic granular sludge treatment device according to claim 1, characterized in that A sludge hopper (12) is arranged in the sedimentation tank (4). The sludge reflux branch pipe (13) extends into the bottom of the sludge hopper (12), and the nozzle of the sludge reflux branch pipe (13) is arranged downward.

3. The variable density self-circulating aerobic granular sludge treatment device according to claim 1, characterized in that It further comprises an aerobic influent diversion channel (6), arranged between the anoxic tank (1) and the micro-aerobic tank (2). The water body in the anoxic tank (1) and part of the water body in the micro-aerobic tank (2) enter the aerobic influent diversion channel (6) to be mixed and then enter the micro-aerobic tank (2).

4. The variable density self-circulating aerobic granular sludge treatment device according to claim 1, characterized in that It further comprises an aerobic sludge recovery channel (7), arranged between the micro-aerobic tank (2) and the aerobic tank (3); Part of the water body in the micro-aerobic tank (2) enters the aerobic sludge recovery channel (7), and part of the water body in the aerobic tank (3) enters the aerobic sludge recovery channel (7); The water bodies from the micro-aerobic tank (2) and the aerobic tank (3) are mixed in the aerobic sludge recovery channel (7), and then part of the water body flows back to the micro-aerobic tank (2), and the other part of the water body enters the aerobic tank (3).

5. The variable-density self-circulating aerobic granular sludge treatment device according to claim 1, wherein It further comprises a degassing channel (8); The degassing channel (8) is arranged between the aerobic tank (3) and the sedimentation tank (4); After the water body in the aerobic tank (3) is degassed in the degassing channel (8), a part of the water body flows back into the aerobic tank (3), and the other part of the water body enters the sedimentation tank (4). The nitrification liquid return branch pipe (18) is located in the degassing channel (8).

6. The variable-density self-circulating aerobic granular sludge treatment device according to claim 5, characterized in that, The pipe orifice of the nitrification liquid return branch pipe (18) faces downward and is located in the lower half area of the degassing channel (8).

7. The variable density self-circulating aerobic granular sludge treatment device according to claim 5, characterized in that It further includes a water distribution pipe (14), one end of which is communicated with the degassing channel (8), and the other end is communicated with the sedimentation tank (4); The pipe section of the water distribution pipe (14) located in the sedimentation tank (4) is a plurality of pipe bodies arranged parallel to the bottom of the sedimentation tank (4), and a plurality of water distribution holes (39) are arranged on the pipe wall of each pipe body.

8. The variable density self-circulating aerobic granular sludge treatment device according to claim 1, characterized in that The aeration device includes an aerator (22) and an acceleration member; The aerator (22) is arranged at the bottoms of the micro-aerobic tank (2) and the aerobic tank (3), and the aerator (22) is used to provide the gas required for the aerobic reaction; The acceleration member includes a premixing cover (35) and a speed maintaining member (34); The premixing cover (35) covers the air outlet end of the aerator (22), and the space between the premixing cover (35) and the aerator (22) forms a first premixing area (33); There is a gap between the premixing cover (35) and the aerator (22) to form a first water return port (30), and the first water return port (30) communicates the internal and external spaces of the first premixing area (33); wherein, the flow area of the release port of the premixing cover (35) is smaller than the flow area of the water inlet of the premixing cover (35) to increase the pressure in the first premixing area (33) under the aeration state; One end of the speed maintaining member (34) is connected to the release port of the premixing cover (35), and the other end extends in a direction away from the premixing cover (35).

9. The variable density self-circulating aerobic granular sludge treatment device according to claim 8, characterized in that It further includes a partition plate (32); The partition plate (32) is arranged in the lower half areas of the micro-aerobic tank (2) and the aerobic tank (3), and the partition plate (32) divides the lower half areas of the aerobic tank (3) and the micro-aerobic tank (2) into a plurality of aeration areas (23), and the aeration device is arranged in the aeration areas (23); The space between two adjacent aeration areas (23) forms an internal reflux channel (24), and a notch for communicating the aeration area (23) and the internal reflux channel (24) is left at the bottom of the partition plate (32), and the water body in the internal reflux channel (24) and the water body in the aeration area (23) flow in opposite directions; A diversion cone (31) is arranged at the bottom of the internal reflux channel (24) to guide the water body in the internal reflux channel (24) to flow back into the aeration area (23).

10. The variable density self-circulating aerobic granular sludge treatment device according to claim 1, characterized in that A sludge filtration layer (26) is formed in the sedimentation tank (4). The lower layer of the sludge filtration layer (26) is a nitrification filtration layer (38), and the upper layer of the sludge filtration layer (26) is a denitrification filtration layer (37). While the sludge filtration layer (26) filters the passing water body, the nitrification filtration layer (38) is used to remove ammonia nitrogen in the water body, and the denitrification filtration layer (37) is used to remove total nitrogen and COD in the water body.

11. The variable density self-circulating aerobic granular sludge treatment device according to claim 3, wherein In the anoxic tank (1), along the water flow path, there are a mixing zone (9), an anoxic diversion channel (10), and an upflow anoxic zone (11) in sequence. The spray pipe (17) and the throat pipe (16) are both located in the mixing zone (9). A second water return port (36) is left between the spray pipe (17) and the throat pipe (16). A part of the water body in the mixing zone (9) flows back into the throat pipe (16) through the second water return port (36). Another part of the water body in the mixing zone (9) flows out from the top and enters the anoxic diversion channel (10). The water body flows downward to the bottom in the anoxic diversion channel (10) and then enters the upflow anoxic zone (11). The water body in the upflow anoxic zone (11) flows upward to the top and then enters the aerobic water inlet diversion channel (6). The second pipe section (20) is located in the anoxic diversion channel (10).

12. The variable-density self-circulating aerobic granular sludge treatment device according to claim 11, wherein It further includes an anoxic return pipe (15), one end of which extends into the throat pipe (16), and the other end is located in the upflow anoxic zone (11). The nozzle of the anoxic return pipe (15) faces upward and extends into the upper half of the upflow anoxic zone (11) so that the anaerobic sewage in the upflow anoxic zone (11) flows back to the mixing zone (9).

13. The variable density self-circulating aerobic granular sludge treatment device according to claim 1, wherein The anoxic tank (1), the micro-aerobic tank (2), the aerobic tank (3), and the sedimentation tank (4) are integrated in one tank body, and different regions divided in the tank body form the anoxic tank (1), the micro-aerobic tank (2), the aerobic tank (3), and the sedimentation tank (4); Or one or more of the anoxic tank (1), the micro-aerobic tank (2), the aerobic tank (3), and the sedimentation tank (4) are composed of separate tank bodies.

14. The variable density self-circulating aerobic granular sludge treatment device according to claim 11, wherein It further includes a lifting stirrer (45) arranged in the mixing zone (9) for accelerating the upward flow of the water body in the throat pipe (16).

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