Internal circulation multi-stage a / o wastewater treatment process and device

Abstract

An internal circulation multi-stage A / O wastewater treatment process and device, relating to the technical field of wastewater treatment. A plurality of bioreactor modules loaded with biological fillers are installed in a biochemical pool, so that the biochemical pool is changed into an internal circulation multi-stage A / O biochemical pool, which is used for wastewater treatment. Carbon sources can be saved and thorough denitrification can be achieved. The total nitrogen of treated wastewater can be less than 1 mg / L, and output water can reach true surface water quality grade IV or III. Further, the process and device can reduce sludge yield by about 50%, remove a return sludge flow and a return water flow, and remove or deactivate a secondary sedimentation tank, thus reducing carbon dioxide emissions and saving more energy.

Description

Internal circulation multi-stage A / O sewage treatment process and equipment Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to an internal circulation multi-stage A / O sewage treatment process and device. Background Art

[0002] Domestic sewage contains a variety of biodegradable pollutants and is usually treated by microbial methods. Activated sludge method, biofilm method, or a combination of the first two methods are commonly used. The activated sludge method generally includes anoxic / aerobic (A / O) process, anaerobic / anoxic / aerobic (A / A / O) process, oxidation ditch process, sequencing batch reactor (MBR) process, etc. The biofilm method includes biological filter process. The combination of activated sludge method and biofilm method usually includes biological contact oxidation method and mobile packing method (MBBR). However, the combination of the above two activated sludge methods and biofilm method has not significantly improved the sewage treatment effect and reflected the effect of energy conservation, carbon reduction, and carbon source saving. Summary of the Invention

[0003] Therefore, the purpose of the present invention is to provide a bioreactor made of biofilm filler that is directly placed in various activated sludge process biochemical pools to form a new internal circulation multi-stage A / O sewage treatment process and device, thereby significantly improving the sewage treatment effect and embodying the effects of energy conservation and carbon reduction, saving carbon sources, and reducing sludge emissions.

[0004] The technical solutions of the present invention are as follows:

[0005] On the one hand, the present invention provides an internal circulation multi-stage A / O sewage treatment process, in which several bioreactor modules loaded with biological fillers are installed in a biochemical pool to transform the biochemical pool into an internal circulation multi-stage A / O biochemical pool; the internal circulation multi-stage A / O biochemical pool is used to treat sewage.

[0006] Furthermore, the internal circulation multi-stage A / O biochemical pool is a biochemical pool with continuous water inflow.

[0007] Furthermore, the internal circulation multi-stage A / O biochemical pool is a biochemical pool with intermittent water inflow.

[0008] On the other hand, the present invention also provides an internal circulation multi-stage A / O sewage treatment device, which adopts the internal circulation multi-stage A / O sewage treatment process described in any of the above items; wherein, the bioreactor module includes a cylinder, a support frame, a biological filler layer, an aeration device and a cleaning gas distribution device; the support frame is arranged at the bottom of the cylinder, and the bioreactor module is supported at the bottom of the biochemical pool by the support frame so that the bioreactor module is completely immersed in water; or the support frame is arranged at the upper part of the cylinder, and the cylinder is suspended at the top of the biochemical pool through the support frame; the biological filler layer is located in the cylinder, and the biological filler layer is formed by biological filler; the aeration device is located in the cylinder, and the aeration device is adapted to the biological filler layer to provide oxygen required by aerobic microorganisms; the cleaning gas distribution device is located in the cylinder, and the cleaning gas distribution device is adapted to the biological filler layer, and the cleaning gas distribution device is used to blow air toward the biological carrier to remove the aged microbial film on the biological carrier.

[0009] Furthermore, the cylinder is made of concrete or fiberglass or plastic or stainless steel or steel frame covered with cloth; the support frame is made of reinforced concrete or fiberglass or steel.

[0010] Furthermore, the aeration device and the cleaning air distribution device are installed below the biological filler layer.

[0011] Furthermore, the biological packing layer is divided into an upper packing layer and a lower packing layer. The upper packing layer is arranged in the upper space of the cylinder, and the lower packing layer is arranged in the lower space of the cylinder; the aeration device is arranged between the upper packing layer and the lower packing layer, and the cleaning gas distribution device is arranged below the lower packing layer; or the aeration device and the cleaning gas distribution device are arranged between the upper packing layer and the lower packing layer, and the cleaning gas distribution device is arranged below the lower packing layer; or the aeration device and the cleaning gas distribution device are arranged between the upper packing layer and the lower packing layer, and the aeration device and the cleaning gas distribution device are arranged below the lower packing layer.

[0012] Furthermore, the biological filler in the biological filler layer includes one or both of a flowing filler and a fixed filler.

[0013] Furthermore, when the flow filler is a heavy filler, the heavy filler is expanded clay or a plastic ring, a filter plate is provided at the lower part of the cylinder, a number of filter heads are installed on the filter plate, and the heavy filler is accumulated on the filter plate; when the flow filler is a light filler, the light filler is a foam plastic bead or a plastic ring, a filter plate is provided at the upper part of the cylinder, a number of filter heads are installed on the filter plate, and the light filler is loaded below the filter plate.

[0014] Furthermore, the fixed filler is a short fiber string formed by short fiber bundles tied on a rope; or the fixed filler is an elastic filler string formed by elastic filler tied on a rope; or the fixed filler is a fiber fabric, non-woven fabric or long fiber bundle; wherein the length of the short fiber string is not greater than 50 mm, and the length of the long fiber bundle is not less than 500 mm.

[0015] Furthermore, the internal circulation multi-stage A / O sewage treatment device also includes an upper support body and a lower support body spaced apart in the cylinder; the upper end of the fixed filler is suspended on the upper support body through an upper connecting piece, and the lower end of the fixed filler is suspended on the lower support body through a lower connecting piece.

[0016] Furthermore, the upper support body and the lower support body are both porous plates or grating plates; the planar shapes of the upper support body and the lower support body are rectangular, square, hexagonal, triangular, circular or other polygonal.

[0017] Furthermore, the aeration device is an aeration pipe or an aeration disk, and the aeration device is connected to the aeration fan through an aeration air inlet pipe; the cleaning air distribution device is a porous tube or a bread tube, and the cleaning air distribution device is connected to the cleaning fan through a cleaning air inlet pipe.

[0018] The technical solution of the present invention has the following advantages:

[0019] The internal circulation multi-stage A / O sewage treatment process provided by the present invention installs several bioreactor modules loaded with biological fillers in a biochemical pool, each bioreactor module is a first-level water purification unit that can circulate water within it, and multiple bioreactor modules together form a multi-stage water purification unit, thereby turning the biochemical pool into an internal circulation multi-stage A / O biochemical pool; using an internal circulation multi-stage A / O biochemical pool for sewage treatment can save carbon source and completely denitrify (the total nitrogen in the sewage after treatment can be less than 1 mg / L, and the effluent can meet the true surface water Class IV or Class III standard); moreover, compared with the process of increasing the treatment capacity by increasing the amount of activated sludge, this treatment process can reduce sludge production (can be reduced by about 50%), can eliminate sludge backflow and water backflow, can eliminate or disable the secondary sedimentation tank, reduce carbon dioxide emissions, be more energy-efficient, and achieve multi-dimensional results. It can be said to be a revolution in the biological treatment process of sewage treatment! Moreover, the internal circulation multi-stage A / O sewage treatment process can be used in combination with other sewage treatment processes, with the chemical sedimentation tank or hydrolysis acidification tank or anaerobic tank as the pre-treatment unit and the biological filter as the post-treatment unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] FIG1 is a schematic diagram of an internal circulation multi-stage A / O process for continuously inflowing water into a biochemical pool in an internal circulation multi-stage A / O wastewater treatment process according to one embodiment of the present invention;

[0022] FIG2 is a schematic diagram of an internal circulation multi-stage A / O process for treating wastewater in an internal circulation multi-stage A / O process for intermittent water inflow to a biochemical pool in an embodiment of the present invention;

[0023] FIG3 is a schematic diagram showing the working principle of a bioreactor module in an internal circulation multi-stage A / O sewage treatment device according to an embodiment of the present invention;

[0024] FIG4 is a schematic diagram of the upper and lower packing layers of a bioreactor module in an internal circulation multi-stage A / O sewage treatment device according to one embodiment of the present invention;

[0025] FIG5 is a schematic diagram of a single packing layer of a bioreactor module in an internal circulation multi-stage A / O sewage treatment device according to an embodiment of the present invention;

[0026] FIG6 is a schematic diagram of fixed fillers in a bioreactor module in an internal circulation multi-stage A / O sewage treatment device according to one embodiment of the present invention;

[0027] FIG7 is a schematic diagram of a heavy filler in a bioreactor module in an internal circulation multi-stage A / O sewage treatment device according to one embodiment of the present invention;

[0028] FIG8 is a schematic diagram of a lightweight filler in a bioreactor module in an internal circulation multi-stage A / O sewage treatment device according to an embodiment of the present invention.

[0029] 801. Pretreatment unit; 802. Continuous water inlet internal circulation multi-stage A / O biochemical tank; 8021. Intermittent water inlet internal circulation multi-stage A / O biochemical tank; 803. Bioreactor module; 804. Advanced treatment unit; 805. Sludge disposal unit; 806. Inlet main pipe; 807. Outlet main pipe; 808. Sludge discharge branch pipe; 809. Sludge discharge main pipe;

[0030] 301, shell; 302, cylinder; 4, cleaning gas distribution device; 5, aeration device; 81, support frame;

[0031] 14. Upper support body; 15. Lower support body; 16. Upper connecting piece; 17. Lower connecting piece;

[0032] 401, upper packing layer; 402, lower packing layer;

[0033] 13, fixed filler; 212, heavy filler; 213, light filler;

[0034] 50. Filter head; 501. Filter plate. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0036] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0038] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] Referring to Figure 1 , this embodiment provides an internal-circulation, multi-stage A / O wastewater treatment process. Several bioreactor modules 803 loaded with biological fillers are installed within a continuously influent biochemical tank, transforming the tank into a continuously influent, internal-circulation, multi-stage A / O biochemical tank 802. This wastewater treatment process is transformed into a new internal-circulation, multi-stage A / O wastewater treatment process. This internal-circulation, multi-stage A / O wastewater treatment process also includes a pretreatment unit 801, an advanced treatment unit 804, and a sludge disposal unit 805.

[0040] The pre-treatment unit 801 includes a screen well and a grit chamber, and the deep treatment unit 804 includes a filtration tank and a disinfection tank.

[0041] Working Principle: Wastewater flows sequentially into pretreatment unit 801, continuous inflow internal circulation multi-stage A / O biochemical tank 802, and advanced treatment unit 804. Once in internal circulation continuous flow multi-stage A / O biochemical tank 802, wastewater undergoes treatment in multi-stage bioreactor modules, gradually reducing wastewater concentration until its biodegradable components, such as COD, BOD, ammonia nitrogen, and total nitrogen, meet discharge standards by the time it exits internal circulation multi-stage A / O biochemical tank 802. Sludge generated by continuous inflow internal circulation multi-stage A / O biochemical tank 802 is discharged into sludge disposal unit 805.

[0042] Referring to Figure 2 , this embodiment also provides an internal-circulation, multi-stage A / O wastewater treatment process. Several bioreactor modules 803 loaded with biological fillers are installed in an intermittently influent, internal-circulation, multi-stage A / O biochemical tank. This tank becomes an intermittently influent, internal-circulation, multi-stage A / O biochemical tank 8021. This wastewater treatment process is transformed into a new wastewater treatment process—an intermittently influent, internal-circulation, multi-stage A / O wastewater treatment process. This intermittently influent, internal-circulation, multi-stage A / O wastewater treatment process also includes a pretreatment unit 801, an advanced treatment unit 804, and a sludge disposal unit 805.

[0043] The pre-treatment unit 801 includes a screen well and a grit chamber, and the deep treatment unit 804 includes a filtration tank and a disinfection tank.

[0044] Working Principle: Sewage flows sequentially into pretreatment unit 801, then flows through the main inlet pipe 806 into several intermittent inflow, internal circulation, multi-stage A / O biochemical tanks 8021. Then, through the main outlet pipe 807, it flows into advanced treatment unit 804. After several hours of treatment in the intermittent inflow, internal circulation, multi-stage A / O biochemical tanks 8021, when biodegradable components such as COD, BOD, ammonia nitrogen, and total nitrogen meet discharge standards, the effluent flows into advanced treatment unit 804 for further removal of total phosphorus and suspended solids, disinfection, and sterilization to meet higher standards for discharge or resource utilization. The wastewater is then reinjected for further treatment. Each of the intermittent inflow, internal circulation, multi-stage A / O biochemical tanks 8021 operates in this manner. If a sufficient number of biochemical tanks is designed, the sewage treatment plant can achieve continuous water inflow and outflow. The sludge generated by the intermittent inflow, internal circulation, multi-stage A / O biochemical tanks 8021 is discharged into sludge disposal unit 805 via sludge branch pipe 808 and main outlet pipe 809.

[0045] 3 , 4 , and 5 , this embodiment provides an internal circulation multi-stage A / O sewage treatment device, which adopts the treatment process in the above embodiment and includes a bioreactor module 803. The bioreactor module 803 is composed of a cylinder 302, a support frame 81, a biological filler layer, an aeration device 5, and a cleaning gas distribution device 4.

[0046] For example, the cylinder 302 can be made of fiberglass reinforced plastics, the support frame 81 can be made of fiberglass reinforced plastics, and the support frame 81 is installed at the bottom of the cylinder 302 .

[0047] The biological filler layer is arranged in the cylinder 302, and the aeration device 5 and the cleaning gas distribution device 4 are installed below the biological filler layer.

[0048] The biological packing layer is divided into two parts: an upper packing layer 401 and a lower packing layer 402. The upper packing layer 401 is arranged in the upper space of the cylinder 302, and the lower packing layer 402 is arranged in the lower space of the cylinder 302. The aeration device 5 is arranged below the upper packing layer 401 and above the lower packing layer 402, and the cleaning gas distribution device 4 is arranged below the lower packing layer 402.

[0049] For example, the aeration device 5 may be an aeration tube, and the cleaning gas distribution device 4 may be a porous tube.

[0050] For example, the aeration device 5 is connected to the aeration fan through an aeration air inlet pipe.

[0051] For example, the cleaning air distribution device 4 is connected to the cleaning blower through a cleaning air inlet pipe.

[0052] For example, the bioreactor module 803 may be cylindrical in shape, and its diameter may be 500 mm.

[0053] When in use, the bioreactor module 803 can be supported on the bottom of the shell 301 of the internal circulation multi-stage A / O biochemical pool 802 by the support frame 81, and the bioreactor module 803 is completely immersed in water.

[0054] Taking the continuous water inflow internal circulation multi-stage A / O biochemical pool 802 as an example, its working principle is as follows:

[0055] Water purification process:

[0056] After the wastewater enters the continuous water inlet, internal circulation, multi-stage A / O biochemical tank 802, the aeration fan is activated, and aeration air is delivered through the aeration inlet pipe to the aeration device 5 within the bioreactor module 803. The aeration air flows from bottom to top through the upper packing layer 401, where aerobic microorganisms catalyze and decompose organic matter and ammonia nitrogen pollutants in the water. Due to the air stripping effect, water enters the lower packing layer 402 from the bottom of the bioreactor module 803, passes through the lower packing layer 402 from bottom to top, and then passes through the upper packing layer 401 from bottom to top. Within the lower packing layer 402, the total nitrogen and organic matter in the water are catalyzed and decomposed by the anoxic denitrifying bacteria in the lower packing layer 402.

[0057] Cleaning process:

[0058] Regularly remove the biofilm and drain the sludge. If the biofilm on the biofill layer degrades, the biofill within bioreactor module 803 needs to be cleaned. The cleaning fan is activated, and cleaning air is delivered through the cleaning air inlet pipe to the cleaning air distribution device 4 within the bioreactor module. The cleaning air passes through the lower packing layer 402 and the upper packing layer 401 from bottom to top. Under the action of air lift, water enters the lower packing layer 402 from the bottom of bioreactor module 803, flows through the lower packing layer 402 from bottom to top, and then passes through the upper packing layer 401 from bottom to top. The biofilm removed by the air is carried out of the bioreactor module with the water and settles to the bottom of the continuously inlet, internally circulating, multi-stage A / O biochemical tank. It is then discharged into the sludge disposal unit 805 through the sludge removal system or pipeline.

[0059] Referring to Figure 6, the fixed filler 13 can be a long fiber bundle. The length of the long fiber bundle is generally not less than 500 mm. The upper end of the long fiber bundle of the fixed filler 13 is suspended on the upper support body 14 via an upper connector 16, and the lower end of the long fiber bundle of the fixed filler 13 is suspended on the lower support body 15 via a lower connector 17. For example, the upper support body 14 and the lower support body 15 can be grating plates, and the grating plates can be made of fiberglass. For example, the planar shape of the upper support body 14 and the lower support body 15 is circular, and the upper support body 14 and the lower support body 15 are installed in the barrel 302 to form a cylindrical bioreactor module 803.

[0060] Working principle: A large number of microorganisms can grow on the fixed filler 13, which can catalytically decompose pollutants such as organic matter, ammonia nitrogen, nitrate nitrogen, total phosphorus, etc. in water.

[0061] 7 , for example, the heavy filler 212 can be ceramsite. The heavy filler 212 is loaded into the cylinder 302. A filter plate 501 is provided at the bottom of the cylinder 302, and a plurality of filter heads 50 are installed on the filter plate 501. The heavy filler 212 is accumulated on the filter plate 501.

[0062] Working principle: A large number of microorganisms can grow on the heavy filler 212, which can catalytically decompose pollutants such as organic matter, ammonia nitrogen, nitrate nitrogen, total phosphorus, etc. in the water.

[0063] Referring to Figure 8 , the lightweight filler 213 can be, for example, foam plastic beads or plastic rings. The lightweight filler 213 is loaded into the cylinder 302. A filter plate 501 is disposed above the cylinder 302, and a plurality of filter heads 50 are mounted on the filter plate 501. The lightweight filler 213 is loaded below the filter plate 501.

[0064] Working principle: A large number of microorganisms can grow on the lightweight filler 213, which can catalytically decompose organic matter, ammonia nitrogen, nitrate nitrogen, and total phosphorus pollutants in the water.

[0065] In summary, the internal circulation multi-stage A / O sewage treatment process and device in this application improves sewage treatment capacity, saves more carbon sources, and removes nitrogen more thoroughly. The total nitrogen content of the treated sewage can be less than 1 mg / L, and the effluent can meet the true surface water Class IV or Class III standards.

[0066] The internal circulation multi-stage A / O sewage treatment process and device in this application can reduce sludge production by about 50%, eliminate sludge backflow and water backflow, eliminate or disable the secondary sedimentation tank, save more energy, and reduce carbon dioxide emissions.

[0067] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. An internal circulation multi-stage A / O sewage treatment process, characterized in that a number of bioreactor modules loaded with biological fillers are installed in the biochemical tank, so that the biochemical tank becomes an internal circulation multi-stage A / O biochemical tank; the internal circulation multi-stage A / O biochemical tank is used for sewage treatment.

2. The internal circulation multi-stage A / O sewage treatment process according to claim 1, wherein, The internal circulation multi-stage A / O biochemical tank is a biochemical tank with continuous water inlet.

3. The internal circulation multi-stage A / O sewage treatment process according to claim 1, characterized in that, The internal circulation multi-stage A / O biochemical tank is a biochemical tank with intermittent water inlet.

4. An internal circulation multi-stage A / O sewage treatment device, characterized in that, The internal circulation multi-stage A / O sewage treatment process according to any one of claims 1 to 3 is adopted; wherein, the bioreactor module includes a cylinder body, a support frame, a biological filler layer, an aeration device and a cleaning air distribution device; the support frame is arranged at the bottom of the cylinder body, and the bioreactor module is supported at the bottom of the biochemical tank through the support frame, so that the bioreactor module is completely immersed in water; or the support frame is arranged at the upper part of the cylinder body, and the cylinder body is suspended at the top of the biochemical tank through the support frame; the biological filler layer is located inside the cylinder body, and the biological filler layer is formed by biological fillers; the aeration device is located inside the cylinder body, and the aeration device is arranged to be adapted to the biological filler layer to provide oxygen required by aerobic microorganisms; the cleaning air distribution device is located inside the cylinder body, and the cleaning air distribution device is arranged to be adapted to the biological filler layer, and the cleaning air distribution device is used to blow air towards the biological carrier to make the aged microbial film on the biological carrier fall off.

5. The internal circulation multi-stage A / O sewage treatment device according to claim 4, characterized in that, The cylinder body is made of concrete or fiberglass or plastic or stainless steel or a steel skeleton covered with fabric; The support frame is made of reinforced concrete or fiberglass or steel.

6. The internal circulation multi-stage A / O sewage treatment device according to claim 4, characterized in that, The aeration device and the cleaning air distribution device are installed below the biological filler layer.

7. The internal circulation multi-stage A / O sewage treatment device according to claim 6, characterized in that, The biological filler layer is divided into an upper filler layer and a lower filler layer. The upper filler layer is arranged in the upper space of the cylinder body, and the lower filler layer is arranged in the lower space of the cylinder body; the aeration device is arranged between the upper filler layer and the lower filler layer, and the cleaning air distribution device is arranged below the lower filler layer; or the aeration device and the cleaning air distribution device are arranged between the upper filler layer and the lower filler layer, and the cleaning air distribution device is arranged below the lower filler layer; or the aeration device and the cleaning air distribution device are arranged between the upper filler layer and the lower filler layer, and the aeration device and the cleaning air distribution device are arranged below the lower filler layer.

8. The internal circulation multi-stage A / O sewage treatment device according to claim 4, characterized in that, The biological fillers in the biological filler layer include one or two of mobile fillers and fixed fillers.

9. The internal circulation multi-stage A / O sewage treatment device according to claim 8, wherein When the mobile filler is a heavy filler, the heavy filler is ceramsite or a plastic ring. A filter plate is arranged at the lower part of the cylinder body, and a number of filter heads are installed on the filter plate, and the heavy filler is piled up on the filter plate; When the mobile filler is a light filler, the light filler is a foam plastic bead or a plastic ring. A filter plate is arranged at the upper part of the cylinder body, and a number of filter heads are installed on the filter plate, and the light filler is filled below the filter plate.

10. The internal circulation multi-stage A / O sewage treatment device according to claim 8, wherein, The fixed filler is a short fiber string formed by tying short fiber bundles on a rope; or the fixed filler is an elastic filler string formed by tying elastic fillers on a rope; or the fixed filler is a fiber fabric, a non-woven fabric or a long fiber bundle; Among them, the length of the short fiber string is not greater than 50 mm, and the length of the long fiber bundle is not less than 500 mm.

11. The internal circulation multi-stage A / O sewage treatment device according to claim 10, characterized in that, It further includes an upper support body and a lower support body which are arranged at intervals in the cylinder body; The upper end of the fixed filler is suspended on the upper support body through an upper connecting piece, and the lower end of the fixed filler is suspended on the lower support body through a lower connecting piece.

12. The internal circulation multi-stage A / O sewage treatment device according to claim 11, characterized in that, Both the upper support body and the lower support body are porous plates or grid plates; The planar shapes of the upper support body and the lower support body are rectangles, squares, hexagons, triangles, circles or other polygons.

13. The internal circulation multi-stage A / O sewage treatment device according to claim 4, characterized in that The aeration device is an aeration pipe or an aeration disc, and the aeration device is connected to an aeration fan through an aeration inlet pipe; The cleaning air distribution device is a perforated pipe or a bread pipe, and the cleaning air distribution device is connected to a cleaning fan through a cleaning inlet pipe.

Images