Annular vertical internal circulation water treatment reactor and method

Abstract

The invention belongs to the technical field of water treatment, and particularly relates to an annular vertical internal circulation water treatment reactor and method. The reactor comprises a reactor shell, a central ring shell, an annular partition plate, an aerobic reaction area, an anaerobic reaction area, an anoxic reaction area, an aeration mechanism, a hollow fiber membrane assembly, a divergent throat pipe, a water inlet / return sludge mixing area, a sediment / filter material self-dispersion area, a variable cross-section filter area, a first annular sludge settling area and a second annular sludge settling area. According to the invention, self-circulation vertical flow is formed in the anoxic reaction zone and the aerobic reaction zone by changing the equipment structure and the internal hydraulic action mode and utilizing the gas stripping effect of aeration; a light filter material filter layer is utilized, and a variable cross-section upward flow anaerobic biological filter layer form is adopted, so that the self-dispersion decontamination effect of the filter layer is realized, and the water consumption and the energy consumption are reduced; and the stability of the effluent quality is improved by utilizing the membrane separation effect of the MBR. According to the reactor disclosed by the invention, the optimal proportion of 1: 3: 5 of the anaerobic reaction zone, the anoxic reaction zone and the aerobic reaction zone is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to an annular vertical internal circulation water treatment reactor and a method. Background Art

[0002] With the increasing improvement of sewage discharge standards, especially the removal of nutritional indicators such as nitrogen and phosphorus in sewage has become an important part of sewage biological treatment. The A / A / O process is a typical biological denitrification and phosphorus removal process, which has been widely used in sewage treatment facilities of different scales.

[0003] The A / A / O process (anaerobic-anoxic-aerobic combined process) generally consists of three reaction zones, namely the anaerobic zone, the anoxic zone and the aerobic zone. The role of the anaerobic zone is to convert some of the macromolecular organic matter in the raw water into small molecular volatile fatty acids (VFA) that are easy to aerobic treatment through hydrolysis and acidification reactions, thereby improving the biochemical properties of the sewage. At the same time, in the anaerobic zone, the metabolic characteristics of polyphosphate bacteria can be used to hydrolyze the polyphosphate in the cell into orthophosphate and release it into the water to obtain energy to maintain survival. The role of the anoxic zone is mainly to use the organic carbon source in the sewage for denitrification reaction under the action of denitrifying bacteria. The nitrate nitrogen in the denitrification reaction comes from the reflux liquid of the aerobic zone, and the carbon source is obtained by adding organic matter such as methanol. The BOD and nitrate nitrogen removal effect of the anoxic zone depends on the reflux ratio of the supernatant in the aerobic zone. The water from the anoxic zone then enters the aerobic zone. The main function of the aerobic zone is to remove BOD in the water and nitrify the ammonia nitrogen in the water. At the same time, polyphosphate bacteria remove phosphorus in the water by absorbing a large amount of phosphorus in an aerobic environment.

[0004] The A / A / O process has been widely used in large-scale sewage treatment plants and is a relatively mature sewage denitrification process. However, since the process requires sludge and supernatant return, and the denitrification process also requires a certain carbon source, this can usually be accomplished by setting up mechanical equipment such as reflux pumps in large-scale sewage treatment processes. However, if it is applied to small-scale decentralized sewage treatment facilities, especially when the water volume fluctuates greatly and it is impossible to set up dedicated management, there will be problems such as complex process operation, poor operating stability, and difficulty in ensuring the effluent water quality.

[0005] At present, small-scale decentralized sewage treatment often faces the situation of large fluctuations in raw water flow. For example, in rural small-scale sewage treatment facilities, the sewage flow varies greatly within a day, while decentralized sewage treatment facilities in some tourist attractions have significant differences in water volume between off-season and peak season, and sometimes even remain in a state of no water treatment for a long time. However, most of the existing small-scale integrated sewage treatment equipment simply reduces the volume of the above A / A / O process, and still retains the linear process mode of the original process in form and structure. Pumps are also used to increase the sludge return and sewage return. This makes the existing small-scale decentralized sewage treatment facilities have the following main problems in actual operation:

[0006] (1) The process facilities are generally in the form of a horizontal linear combination, resulting in a large footprint for the overall equipment.

[0007] (2) The sludge return and supernatant return of small-scale sewage treatment facilities are operated by mechanical pumps, which have problems such as high pump failure rate and poor automated operation management.

[0008] (3) Anaerobic filtration is often used in the anaerobic section of small-scale sewage treatment facilities. However, since conventional downward flow filtration is prone to clogging, a large amount of clean water is required for backwashing, which increases water and energy consumption.

[0009] (4) The sedimentation effect of the effluent from decentralized small-scale sewage facilities is usually difficult to control, resulting in unstable effluent quality.

[0010] In response to the above problems, existing equipment currently uses membrane technology as a solid-liquid separation method for effluent, replacing the sedimentation process, thereby improving the stability of effluent water quality. However, since membrane technology itself is only an efficient solid-liquid separation method, its denitrification effect must be combined with the denitrification treatment process of sewage to achieve the effluent water quality standard. Therefore, only by organically combining membrane technology and biological treatment to form an MBR process can the problem of sewage treatment operation stability be effectively solved.

[0011] The existing conventional MBR process only uses membrane technology for solid-liquid separation. Although it greatly improves the separation efficiency, it does not effectively simplify the operation of small decentralized sewage treatment equipment. In addition, in the nitrification and denitrification process of denitrification, the return of sludge and sewage usually requires mechanical pumps to increase, which makes it difficult for existing small sewage treatment equipment to be widely used in unattended operation conditions.

[0012] In view of the problems existing in the above small-scale A / A / O treatment equipment, the present invention has innovated the reactor structure and operation method, so that it can achieve low-maintenance and unattended operation while ensuring the water quality of the effluent, so as to meet the needs of a large number of small-scale decentralized sewage treatment. Summary of the invention

[0013] The present invention discloses an annular vertical internal circulation water treatment reactor and method. In view of the problems described in the background technology section, the present invention forms a vertical flow self-circulation in the anoxic reaction zone and the aerobic reaction zone by changing the equipment structure and the internal hydraulic action mode, utilizing the air lift effect of aeration; utilizing a light filter material filter layer and adopting a variable cross-section upward flow anaerobic biological filter layer form, the self-dispersion and pollution cleaning effect of the filter layer is achieved, and water consumption and energy consumption are reduced; utilizing the membrane separation effect of MBR, the stability of the effluent water quality is improved. The reactor of the present invention realizes an optimized ratio of 1:3:5 among the anaerobic / anoxic / aerobic reaction zones.

[0014] To achieve the above purpose, the technical solution of the present invention is:

[0015] A ring-shaped vertical internal circulation water treatment reactor comprises: a reactor shell, a central ring shell arranged in the middle of the reactor shell, and a ring-shaped partition plate arranged between the central ring shell and the reactor shell, wherein a variable cross-section filter zone with a large lower cross-section diameter and a small upper cross-section diameter is formed in the central ring shell, the variable cross-section filter zone is filled with a light filter material, anaerobic microorganisms grow on the outer surface of the light filter material, and the variable cross-section filter zone forms an anaerobic reaction zone; an anoxic reaction zone is formed between the central ring shell and the ring-shaped partition plate, and an aerobic reaction zone is formed between the ring-shaped partition plate and the reactor shell, the bottom of the ring-shaped partition plate is connected to the anoxic reaction zone and the aerobic reaction zone through a plurality of through holes evenly distributed around the axis, an aeration mechanism is arranged at the bottom of the aerobic reaction zone, and water flow is driven to circulate vertically between the anoxic reaction zone and the aerobic reaction zone through the aeration mechanism, a hollow fiber membrane assembly is arranged inside the aerobic reaction zone, and the hollow fiber membrane assembly Aerobic microorganisms grow on the surface, the top of the hollow fiber membrane assembly is connected to a clean water tank through an outlet pipe, the outlet pipe is provided with a vacuum pump, the bottom of the aerobic reaction zone forms a first annular sludge settling zone, the bottom end of the central ring shell extends downward and forms a precipitation / filter material self-dispersion zone and an inlet / return sludge mixing zone from top to bottom in sequence, the outer periphery of the inlet / return sludge mixing zone constitutes a second annular sludge settling zone, a gradually expanding throat is provided in the middle of the inlet / return sludge mixing zone, the upper end of the gradually expanding throat is in a trumpet shape, and the lower end is in a connecting pipe shape, the bottom end of the connecting pipe passes through the bottom of the central ring shell and is connected to the raw water tank through the inlet pipe, a booster pump is provided on the inlet pipe, the connecting pipe is connected to the first annular sludge settling zone through a sludge return pipe, the second annular sludge settling zone is connected to a sludge tank through a sludge pipe, and a triangular water distribution weir is provided at the top of the central ring shell.

[0016] Preferably, the volume ratio of the anaerobic reaction zone, the anoxic reaction zone, and the aerobic reaction zone is 1:3:5.

[0017] Preferably, the reactor shell is a first annular shell, and the center ring shell includes a second annular shell located at the upper part and a truncated cone shell integrally connected to the bottom end of the second annular shell, the small diameter end of the truncated cone shell is sealed and fixedly connected to the bottom end of the second annular shell, and the bottom of the reactor shell is integrally connected with an annular plate inclined inwardly, the annular plate is opposite to the side wall of the truncated cone shell, and the bottom end of the annular plate is sealed and fixedly connected to the bottom end of the truncated cone shell, the inclination angles of the annular plate and the side wall of the truncated cone shell are both 60°, and a first annular sludge settling area is formed between the annular plate and the outer wall of the truncated cone shell.

[0018] Preferably, the aeration mechanism includes a blower, an aeration pipe, and an aeration head. The aeration pipe surrounds the annular partition and is arranged in the aerobic reaction zone below the hollow fiber membrane assembly. The aeration heads are evenly distributed on the top of the aeration pipe. The aeration pipe is connected to the blower through a vent pipe passing through the reactor shell.

[0019] Preferably, the top of the central ring shell is higher than the top of the annular partition, and the sludge return pipe is a U-shaped structure. The top of the U-shaped structure passes through the upper part of the side wall of the central ring shell. One end of the sludge return pipe is connected to the connecting pipe and the other end is connected to the first annular sludge sedimentation area. The top of the U-shaped structure is also connected to a siphon breaking pipe.

[0020] Preferably, a water-permeable plate is provided on the upper portion of the central ring shell, a number of water-collecting caps are evenly distributed on the water-permeable plate, the light filter material is a hollow plastic ball with a diameter of 2 to 4 mm, the light filter material is filled in the second annular shell below the water-permeable plate and partially filled in the truncated cone-shaped shell, the precipitation / filter material self-dispersion zone constitutes a dispersion space for the light filter material, and the space size of the precipitation / filter material self-dispersion zone satisfies that: after the light filter material enters the dispersion space from the variable-section filtration zone, the spacing between the filter materials is enlarged, so that the sludge and impurities entrained between the filter materials are settled.

[0021] Preferably, a guide block is provided above the gradually expanding throat, and a settling plate with an inverted "V"-shaped cross-section surrounds the outer periphery of the gradually expanding throat, and a second annular sludge settling area is formed between the outer surface of the settling plate and the inner wall of the center ring shell.

[0022] A method for self-cleaning lightweight filter media in an annular vertical internal circulation water treatment reactor comprises: during a period of time when no sewage is treated, a booster pump is stopped, and the lightweight filter media enters a sedimentation / filter media self-dispersion zone as the water level drops; as the gaps between the filter media become larger, the sludge and impurities between the filter media settle to a second annular sludge settling zone due to their own gravity; when the liquid level of a central annular shell drops to a permeable plate, air is automatically introduced into a siphon breaking pipe to prevent the sewage in the first annular sludge settling zone from entering the sedimentation / filter media self-dispersion zone due to the siphon effect of the sludge reflux pipe.

[0023] Preferably, after the lightweight filter material enters the sedimentation / filter material self-dispersion zone as the water level drops, the booster pump is intermittently started and shut down. During this process, the lightweight filter material enters the variable cross-section filtration zone as the liquid level rises, and then falls into the sedimentation / filter material self-dispersion zone with the liquid level. After staying for a period of time, it rises with the liquid level again and enters the variable cross-section filtration zone. This operation is repeated while always keeping the liquid level below the permeable plate to achieve self-cleaning of the lightweight filter material.

[0024] The beneficial effects of the annular vertical internal circulation water treatment reactor and method of the present invention are:

[0025] First, it solves the problem of hydraulic internal reflux of the supernatant in the denitrification process. The reactor adopts a ring structure. By opening the bottom of the two outer ring structures and utilizing the air lift effect of the aeration process, the vertical internal automatic circulation of sewage between the aerobic and anoxic reaction zones is achieved, thereby eliminating the need for a reflux pump, simplifying the operation and management of small sewage treatment facilities and reducing treatment energy consumption.

[0026] Secondly, it solves the problem of clogging of anaerobic biological filter layers. Conventional downward flow anaerobic filter layers will be seriously clogged after running for a certain period of time due to the deposition and compaction of intercepted impurities, and are difficult to clean. The present invention uses lightweight filter media as anaerobic biological carriers, changes the downward flow into an upward flow, and adopts an upward flow structure with a variable cross-section. On the one hand, during anaerobic filtration, the filter layer is automatically compacted by the lifting effect of the accelerated water flow. On the other hand, in the stage without sewage treatment, the filter layer descends with the water flow to the gradually expanding space (precipitation / filter material self-dispersion zone), so that the filter material layer is automatically dispersed, and the impurities and sludge intercepted between particles automatically fall off and separate. Solve the problem of clogging of the biological filter layer.

[0027] Third, the problem of carbon source supplementation is solved. The present invention places the anaerobic reaction zone adjacent to the anoxic reaction zone, and the carbon source in the effluent of the anaerobic reaction zone can be directly used as the denitrification carbon source in the anoxic reaction zone, thereby eliminating the need for supplementation of an external carbon source.

[0028] Fourth, the problem of automatic sludge backflow is solved. The present invention adopts a gradually expanding water inlet mixing zone with a venturi tube structure in the water inlet area. By setting a gradually expanding throat, the negative pressure suction effect can be generated by the water inlet pressure, and the residual sludge at the bottom of the anoxic / aerobic zone can be automatically sucked into the water inlet mixing zone to mix with the raw water, achieving the goal of automatic sludge backflow without the power of the reflux pump of the A / A / O process. This suction effect can also be controlled by adjusting the water inlet flow rate, without the need for complex automatic control facilities.

[0029] Fifth, a membrane module with hollow fiber membrane as the main body is set in the aerobic reaction zone to form an MBR reactor. The high-efficiency separation effect of the membrane ensures the effluent quality and solves the operation stability and effluent quality problems of small-scale decentralized sewage treatment facilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a front view structural schematic diagram of the present invention during normal operation.

[0031] Figure 2 It is a schematic diagram of the cross-sectional structure at AA during normal operation of the present invention.

[0032] Figure 3 This is a schematic diagram of the self-cleaning principle of the lightweight filter material in the present invention without sewage treatment.

[0033] In the figure: 1. Reactor shell; 2. Annular baffle; 3. Center ring shell; 4. Triangular water distribution weir; 5. Permeable plate; 6. Water collecting cap; 7. Sludge return pipe; 8. Hollow fiber membrane assembly; 9. Light filter media; 10. Aeration head; 11. Aeration pipe; 12. Guide block; 13. Gradually expanding throat; 14. Vacuum pump; 15. Booster pump; 16. Water inlet valve; 17. Sludge discharge valve; 18. Water inlet pipe; 19. Sludge pipe; 20. .Outlet pipe; 21.Siphon breaking pipe; 22.Blower; 23.Raw water tank; 24.Clean water tank; 25.Sludge tank; 01.Inlet / return sludge mixing zone; 02.Sedimentation / filter material self-dispersion zone; 03.Variable cross-section filtration zone; 04.Anaerobic reaction zone; 05.Anoxic reaction zone; 06.Aerobic reaction zone; 07.Second annular sludge settling zone; 08.First annular sludge settling zone; 09.Annular plate; 010.Settling plate. DETAILED DESCRIPTION

[0034] The following description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0035] The following embodiments may be understood as individually expressing a part of a local structure or method of the present invention, or may be understood as a combination of the embodiments to explain the connotation of a larger structure or method of the present invention.

[0036] Example 1

[0037] A ring-shaped vertical internal circulation water treatment reactor, such as Figure 1-3As shown, it includes: a reactor shell 1, a central ring shell 3 arranged in the middle of the reactor shell 1, and an annular partition 2 arranged between the central ring shell 3 and the reactor shell 1, wherein a variable cross-section filtration area 03 with a large lower cross-section diameter and a small upper cross-section diameter is formed in the central ring shell 1, and the variable cross-section filtration area 03 is filled with a lightweight filter material 9, and anaerobic microorganisms grow on the outer surface of the lightweight filter material 9, and the variable cross-section filtration area 03 forms an anaerobic reaction area 04; an anoxic reaction area 05 is formed between the central ring shell 3 and the annular partition 2, and an aerobic reaction area 06 is formed between the annular partition 2 and the reactor shell 1, and the bottom of the annular partition 2 is connected to the anoxic reaction area 05 and the aerobic reaction area 06 through a plurality of through holes evenly distributed around the axis, and an aerobic reaction area 06 is provided with an aeration mechanism at the bottom, and water circulation is driven between the anoxic reaction area 05 and the aerobic reaction area 06 by the aeration mechanism, and a hollow fiber membrane assembly 8 is provided inside the aerobic reaction area 06, and aerobic microorganisms grow on the surface of the hollow fiber membrane assembly 8 The top of the hollow fiber membrane assembly 8 is connected to a clean water tank 24 through an outlet pipe 20, and a vacuum pump 14 is provided on the outlet pipe 20. The bottom of the aerobic reaction zone 06 forms a first annular sludge settling zone 08. The bottom end of the central ring shell 3 extends downward and forms a sedimentation / filter material self-dispersion zone 02 and an inlet / return sludge mixing zone 01 from top to bottom. The outer periphery of the inlet / return sludge mixing zone 01 constitutes a second annular sludge settling zone 07. A gradually expanding throat 13 is provided in the center, the upper end of which is in the shape of a bell mouth, and the lower end is in the shape of a connecting pipe. The bottom end of the connecting pipe passes through the bottom of the center ring shell 3 and is connected to the raw water tank 23 through an inlet pipe 18. A booster pump 15 is provided on the inlet pipe 18. The connecting pipe is connected to the first annular sludge settling area 08 through a sludge return pipe 7. The second annular sludge settling area 07 is connected to a sludge tank 25 through a sludge pipe 19. A triangular water distribution weir 4 is provided at the top of the center ring shell 3.

[0038] Example 2

[0039] like Figure 1 As shown, the volume ratio of the anaerobic reaction zone 04, the anoxic reaction zone 05, and the aerobic reaction zone 06 is 1:3:5.

[0040] Example 3

[0041] like Figure 1 , 2As shown, the reactor shell 1 is a first annular shell, and the center ring shell 3 includes a second annular shell located at the upper part and a truncated cone shell integrally connected to the bottom end of the second annular shell, the small diameter end of the truncated cone shell is sealed and fixedly connected to the bottom end of the second annular shell, and the bottom of the reactor shell is integrally connected with an annular plate 09 inclined inwardly, the annular plate 09 is opposite to the side wall of the truncated cone shell, and the bottom end of the annular plate 09 is sealed and fixedly connected to the bottom end of the truncated cone shell, the inclination angles of the annular plate 09 and the side wall of the truncated cone shell are both 60°, and the first annular sludge settling area 08 is formed between the annular plate 09 and the outer wall of the truncated cone shell.

[0042] Example 4

[0043] like Figure 2 As shown, the aeration mechanism includes a blower 22, an aeration pipe 11, and an aeration head 10. The aeration pipe 11 surrounds the annular partition 2 and is arranged in the aerobic reaction zone 06 below the hollow fiber membrane assembly 8. The aeration heads 10 are evenly distributed on the top of the aeration pipe 11. The aeration pipe 11 is connected to the blower 22 through a ventilation pipe passing through the reactor shell 1.

[0044] Example 5

[0045] like Figure 2 , 3 As shown, the top of the central ring shell 3 is higher than the top of the annular partition 2, and the sludge return pipe 7 is a U-shaped structure. The top of the U-shaped structure passes through the upper part of the side wall of the central ring shell 3. One end of the sludge return pipe 7 is connected to the connecting pipe and the other end is connected to the first annular sludge sedimentation area 08. The top of the U-shaped structure is also connected to a siphon breaking pipe 21.

[0046] Example 6

[0047] like Figure 1 , 2 As shown in FIG. 3 , a water-permeable plate 5 is provided on the upper portion of the central ring shell 3, and a plurality of water-collecting caps 6 are evenly distributed on the water-permeable plate 5. The light filter material 9 is a hollow plastic ball with a diameter of 2 to 4 mm. The light filter material 9 is filled in the second annular shell below the water-permeable plate 5 and is partially filled in the truncated cone shell. The precipitation / filter material self-dispersion zone 02 constitutes a dispersion space for the light filter material 9. The space size of the precipitation / filter material self-dispersion zone 02 satisfies that: after the light filter material 9 enters the dispersion space from the variable cross-section filtration zone, the spacing between the filter materials is enlarged, so that the sludge and impurities entrained between the filter materials are settled.

[0048] Example 7

[0049] like Figure 1As shown, a guide block 12 is provided above the gradually expanding throat, and a sedimentation plate 010 with an inverted "V"-shaped cross-section surrounds the outer periphery of the gradually expanding throat 13, and a second annular sludge sedimentation area 07 is formed between the outer surface of the sedimentation plate 010 and the inner wall of the center ring shell 3.

[0050] In this embodiment, the guide block 12 can be fixedly connected to the inner wall of the center ring housing 3 through a connecting rod.

[0051] Example 8

[0052] Based on the above embodiments, this embodiment discloses a method for self-cleaning lightweight filter material in an annular vertical internal circulation water treatment reactor, such as Figure 1-3 As shown, it includes: during the time period without sewage treatment, the booster pump 15 stops, and the lightweight filter material 9 enters the sedimentation / filter material self-dispersion area 02 as the water level drops. As the gaps between the filter materials become larger, the sludge and impurities between the filter materials settle to the second annular sludge sedimentation area 07 due to their own gravity; when the liquid level of the central ring shell 3 drops to the permeable plate 5, the siphon breaking pipe 21 automatically enters the air to prevent the sludge reflux pipe 7 from causing the sewage in the first annular sludge sedimentation area 08 to enter the sedimentation / filter material self-dispersion area 02 due to the siphon effect.

[0053] In this embodiment, the siphon breaking tube 21 is a prior art, and its structure and principle are detailed in the prior art disclosure.

[0054] Example 9

[0055] like Figure 1-3 As shown, after the lightweight filter material 9 enters the sedimentation / filter material self-dispersion zone 02 as the water level drops, the booster pump 15 is intermittently started and shut down. During this process, the lightweight filter material 9 enters the variable cross-section filtration zone 03 as the liquid level rises, and then falls into the sedimentation / filter material self-dispersion zone 02 as the liquid level. After staying for a period of time, it rises again with the liquid level and enters the variable cross-section filtration zone 03. This operation is repeated and the liquid level is always kept below the permeable plate 5 to achieve self-cleaning of the lightweight filter material 9.

[0056] This embodiment provides another way to achieve self-cleaning, that is, on the basis of Example 8, a small amount of raw water is reserved at the end of sewage treatment, and the sludge in the lightweight filter material is settled into the second annular sludge settling area through repeated upward squeezing, downward dispersion, and sludge sedimentation for a certain period of time during the dispersion process of the lightweight filter material, thereby achieving self-cleaning of the lightweight filter material.

[0057] The working principle of the present invention is described in detail as follows:

[0058] 1. During the sewage treatment process, the raw water, i.e. sewage, enters the gradually expanding throat through the water inlet pipe, and the Bernoulli principle is used to produce a suction effect, so that the sludge in the first annular sludge settling area is sucked to the connecting pipe through the sludge return pipe, and then flows out from the upper end of the gradually expanding throat together with the sewage, thereby achieving the mixing of sewage and sludge.

[0059] 2. The mixed sewage is guided by the guide block 12 and evenly distributed in the sedimentation / filter material self-dispersion area 02. Since the cross-section of the water outlet from the gradually expanding throat suddenly expands, the sewage flow rate drops rapidly, which can promote the sedimentation and separation of suspended matter in the sewage in this area. The separated sludge enters the second annular sludge sedimentation area 07, and the separated sewage flows upward into the anaerobic reaction area 04.

[0060] 3. The sewage flows upward and pushes the lightweight filter material 9 into the filling position, squeezing each other to form a variable cross-section filter area 03, and the anaerobic microorganisms growing on the surface of the lightweight filter material 9 are used for anaerobic hydrolysis treatment.

[0061] 4. After the reaction in the anaerobic reaction zone 04, the effluent passes through the permeable plate with a water collecting cap to the top of the central ring shell, and then is evenly distributed to the anoxic reaction zone through the triangular water distribution weir 4. In this space, the treated raw water in the anaerobic reaction zone and the circulating water in the aerobic reaction zone are fully mixed to form an anoxic reaction zone to complete the denitrification. Since the raw water in the anaerobic reaction zone has sufficient carbon source, and the mixed liquid in the aerobic reaction zone is continuously circulated with the anoxic reaction zone under the action of aeration and air lift, the anoxic reaction zone and the aerobic reaction zone form a vertical anoxic-aerobic distribution balance to achieve the purpose of continuous and stable denitrification.

[0062] 5. The effluent from the anoxic reaction zone continuously enters the aerobic reaction zone 06 from the through hole. A hollow fiber membrane assembly is arranged in the aerobic reaction zone. Through the suction action of the vacuum pump 14, clean water is continuously sucked out to the clean water tank, and the activated sludge is retained in the aerobic reaction zone. The settled sludge enters the first annular sludge settling zone, and automatically enters the sedimentation / filter material self-dispersion zone 02 under the suction of the sludge pipe reflux pipe, and then settles to the second annular sludge settling zone, and then is discharged to the sludge tank through the sludge pipe 19.

[0063] 6. When the amount of sewage in the raw water tank drops to a certain height (which can be detected by a liquid level meter), the booster pump stops. At this time, the water level in the anaerobic reaction zone automatically drops, and the lightweight filter material 9 automatically disperses in the sedimentation / filter material self-dispersion zone 02 due to its own gravity. The impurities and sludge trapped between the filter materials automatically settle to the second annular sludge sedimentation zone by gravity, realizing the self-cleaning of the lightweight filter material. In this process, in order to prevent the sewage in the first annular sludge sedimentation zone from being siphoned to the sedimentation / filter material self-dispersion zone 02 through the sludge return pipe due to the drop in the liquid level, a siphon breaking pipe 21 is set at the top of the sludge return pipe. When the liquid level drops to the permeable plate 5, the siphon breaking pipe automatically enters the air to invalidate the siphon effect, thereby blocking the water flow in the aerobic reaction zone. After the water inlet is restored, the lightweight filter material automatically resets under the action of the rising water flow to form a variable cross-section filtration zone.

[0064] 7. The inlet / return sludge mixing zone of the present invention is located in the middle area at the bottom of the reactor, and is provided with a gradually expanding throat-shaped pipe. The connecting pipe at the bottom of the gradually expanding throat-shaped pipe is connected to one end of the sludge return. When the raw water is pressurized by the booster pump, a negative pressure suction effect is generated in the connecting pipe, which can make the sludge in the first annular sludge settling zone return and mix with the raw water. The mixed sludge can hydrolyze the macromolecular organic matter and the difficult-to-degrade organic matter in the raw water under anaerobic conditions to form small molecular organic matter that is easy to be biologically oxidized, thereby promoting the efficiency of subsequent biological treatment. At the same time, this mixing is conducive to the improvement of sludge settling performance.

[0065] 8. A guide block is set in the precipitation / filter material self-dispersion area 02 to dissipate energy and guide the outlet water of the gradually expanding throat. The mixed sewage after the diversion has a sudden expansion of the water flow section, and the rising flow rate drops rapidly, thus forming a relatively static separation environment. The impurities in the raw water can separate from the water by using the inertia difference, achieving the primary precipitation effect of the raw water, which is beneficial to the subsequent anaerobic biological treatment. As mentioned above, this area is also used for self-cleaning of lightweight filter media at the end of sewage treatment.

[0066] 9. The variable cross-section filtration zone is composed of a second annular shell and a truncated cone shell. The cross-sectional area of ​​the truncated cone shell gradually decreases from bottom to top. Since the water inlet flow rate remains unchanged, the cross-sectional area decreases. According to the formula Q=A·υ, the water flow velocity will gradually increase, so that the lightweight filter material in this area is automatically compressed under the action of hydraulic pressure to form an anaerobic reaction zone filtration layer.

[0067] 10. The anoxic reaction zone is connected to the anaerobic reaction zone through a triangular water distribution weir on the one hand, and is connected to the aerobic reaction zone through the top of the annular partition on the other hand. The volume ratio of the anaerobic reaction zone: anoxic reaction zone: aerobic reaction zone = 1:3:5. The water from the anaerobic reaction zone contains a large amount of carbon source, which automatically provides a carbon source for the denitrification in the anoxic reaction zone, so there is no need to add an external carbon source. Through the air lift effect of aeration in the aerobic reaction zone, the anoxic reaction zone and the aerobic reaction zone form an internal circulation of water flow in the vertical direction, which occupies a small area. At the same time, a stable structure of anoxic reaction zone and aerobic reaction zone is also formed vertically. The nitrate formed by oxidation in the aerobic reaction zone can be continuously provided to the denitrifying bacteria in the anoxic reaction zone, forming a continuous and stable denitrification effect.

[0068] 11. The first annular sludge settling area is a 60 O The sloped annular sludge collection area and the aerobic reaction area are equipped with hollow fiber membrane components to form an aerobic MBR reactor, which replaces the secondary sedimentation tank to achieve mud-water separation and ensure the stability of the effluent water quality. The hollow fiber membrane component - MBR membrane component discharges water through the suction action of the vacuum pump, while the sludge in the aerobic reaction area is intercepted, achieving efficient separation of mud and water.

[0069] 12. An annular aeration pipe is set at the bottom of the aerobic reaction zone. On the one hand, aeration provides oxygen for the biodegradation of the aerobic reaction zone. On the other hand, the airflow lifting effect of aeration promotes the water flow to form a vertical internal circulation, so as to achieve the spatial distribution of anoxic / aerobic areas and realize the biological denitrification effect of nitrification / denitrification. Through the biodegradation of the aerobic reaction zone, the BOD and ammonia nitrogen in the water can be effectively reduced, and then separated by the membrane components of the MBR, so that the effluent water quality can be stabilized and meet the standards. The sludge at the bottom of the aerobic reaction zone is connected to the gradually expanding throat through the U-shaped sludge return pipe, and automatically returns to the sedimentation / filter material self-dispersion zone 02, realizing the sludge return without the power of the return pump.

[0070] 13. The outer periphery of the gradually expanding throat is surrounded by a settling plate with an inverted "V"-shaped cross section. Due to the shielding effect of the settling plate, the sludge precipitated in the second annular sludge settling area is not affected by the influent water flow. When the anaerobic biological filter layer is self-cleaning, the trapped impurities between the filter layers will also automatically settle in the second annular sludge settling area. The annular bucket-shaped structure of the second annular sludge settling area is conducive to the collection and removal of sludge. The sludge precipitated in the second annular sludge settling area is regularly removed through the sludge pipe to maintain the effective operation of the reactor biological system.

[0071] Experimental example:

[0072] The "annular vertical internal circulation water treatment reactor" was used to treat domestic sewage in a residential area. The treatment scale was 500L / h, and the results are shown in Table 1.

[0073] As can be seen from Table 1, the reactor has good effects on the removal of BOD, SS and ammonia nitrogen in water. The removal rate of BOD, SS and ammonia nitrogen in the reactor is about 97%, 99% and 94% respectively. The effluent can reach the Class A standard.

[0074] The operation of the reactor can be realized automatically by hydraulic regulation.

[0075] Table 1 The effect of the reactor on the sewage treatment of the community

[0076]

Claims

1. A ring-shaped vertical internal circulation water treatment reactor, characterized by comprising: A reactor shell, a central ring shell arranged in the middle of the reactor shell, and an annular partition plate arranged between the central ring shell and the reactor shell. A variable cross-section filtration zone with a large lower cross-section diameter and a small upper cross-section diameter is formed in the central ring shell. The variable cross-section filtration zone is filled with a lightweight filter material. Anaerobic microorganisms grow on the outer surface of the lightweight filter material, and the variable cross-section filtration zone forms an anaerobic reaction zone; an anoxic reaction zone is formed between the central ring shell and the annular partition plate, and an aerobic reaction zone is formed between the annular partition plate and the reactor shell. The bottom of the annular partition plate is connected to the anoxic reaction zone and the aerobic reaction zone through a plurality of through holes evenly distributed around the axis. An aeration mechanism is provided at the bottom of the aerobic reaction zone. The water flow circulation between the anoxic reaction zone and the aerobic reaction zone is driven by the aeration mechanism. A hollow fiber membrane assembly is provided inside the aerobic reaction zone, and aerobic microorganisms grow on the surface of the hollow fiber membrane assembly. The top of the hollow fiber membrane assembly is connected to a clean water tank through an outlet pipe, and a vacuum pump is provided on the outlet pipe. A first annular sludge settling zone is formed at the bottom of the aerobic reaction zone. The bottom end of the central ring shell extends downward and forms a precipitation / filter material self-dispersion zone and an inlet / return sludge mixing zone from top to bottom in sequence. The periphery of the inlet / return sludge mixing zone constitutes a second annular sludge settling zone. A gradually expanding throat is provided in the middle of the inlet / return sludge mixing zone. The upper end of the gradually expanding throat is in a trumpet shape, and the lower end is in a connecting pipe shape. The bottom end of the connecting pipe passes through the bottom of the central ring shell and is connected to the raw water tank through the inlet pipe. A booster pump is provided on the inlet pipe. The connecting pipe is connected to the first annular sludge settling zone through a sludge return pipe. The second annular sludge settling zone is connected to a sludge tank through a sludge pipe. A triangular water distribution weir is provided at the top of the central ring shell.

2. The annular vertical internal circulation water treatment reactor according to claim 1, characterized in that: The volume ratio of the anaerobic reaction zone, the anoxic reaction zone and the aerobic reaction zone is 1:3:

5.

3. The annular vertical internal circulation water treatment reactor according to claim 2, characterized in that: The reactor shell is a first annular shell, and the center ring shell includes a second annular shell located at the top and a truncated cone shell integrally connected to the bottom end of the second annular shell. The small diameter end of the truncated cone shell is sealed and fixedly connected to the bottom end of the second annular shell. The bottom of the reactor shell is integrally connected with an annular plate inclined inwardly, the annular plate is opposite to the side wall of the truncated cone shell, and the bottom end of the annular plate is sealed and fixedly connected to the bottom end of the truncated cone shell. The inclination angles of the annular plate and the side wall of the truncated cone shell are both 60°, and a first annular sludge settling area is formed between the annular plate and the outer wall of the truncated cone shell.

4. The annular vertical internal circulation water treatment reactor according to claim 3, characterized in that: The aeration mechanism includes a blower, an aeration pipe, and an aeration head. The aeration pipe surrounds the annular partition and is arranged in the aerobic reaction zone below the hollow fiber membrane module. The aeration heads are evenly distributed on the top of the aeration pipe. The aeration pipe is connected to the blower through a vent pipe passing through the reactor shell.

5. The annular vertical internal circulation water treatment reactor according to claim 4, characterized in that: The top of the central ring shell is higher than the top of the annular partition. The sludge return pipe is a U-shaped structure. The top of the U-shaped structure passes through the upper part of the side wall of the central ring shell. One end of the sludge return pipe is connected to the connecting pipe and the other end is connected to the first annular sludge sedimentation area. The top of the U-shaped structure is also connected to a siphon breaking pipe.

6. The annular vertical internal circulation water treatment reactor according to claim 5, characterized in that: A water-permeable plate is provided on the upper part of the central ring shell, and a plurality of water collecting caps are evenly distributed on the water-permeable plate. The light filter material is a hollow plastic ball with a diameter of 2 to 4 mm. The light filter material is filled in the second annular shell below the water-permeable plate and partially filled in the truncated cone shell. The precipitation / filter material self-dispersion zone constitutes a dispersion space for the light filter material. The space size of the precipitation / filter material self-dispersion zone satisfies that: after the light filter material enters the dispersion space from the variable cross-section filtration zone, the spacing between the filter materials is enlarged, so that the sludge and impurities entrained between the filter materials are settled.

7. The annular vertical internal circulation water treatment reactor according to claim 6, characterized in that: A guide block is arranged above the gradually expanding throat pipe, and a settling plate with an inverted "V"-shaped cross section surrounds the outer periphery of the gradually expanding throat pipe, and a second annular sludge settling area is formed between the outer surface of the settling plate and the inner wall of the central ring shell.

8. A method for self-cleaning lightweight filter media in an annular vertical internal circulation water treatment reactor as claimed in claim 7, characterized in that it comprises: During the period when there is no sewage treatment, the booster pump stops, and the light filter media enters the sedimentation / filter media self-dispersion area as the water level drops. As the gaps between the filter media become larger, the sludge and impurities between the filter media settle to the second annular sludge sedimentation area due to their own gravity; when the liquid level of the center ring shell drops to the permeable plate, the siphon breaking pipe automatically enters the air to prevent the sludge return pipe from causing the sewage in the first annular sludge sedimentation area to enter the sedimentation / filter media self-dispersion area due to the siphon effect.

9. A method for self-cleaning lightweight filter media in an annular vertical internal circulation water treatment reactor as claimed in claim 8, characterized in that: After the lightweight filter material enters the sedimentation / filter material self-dispersion zone as the water level drops, the booster pump is intermittently started and shut down. During this process, the lightweight filter material enters the variable cross-section filtration zone as the liquid level rises, and then falls into the sedimentation / filter material self-dispersion zone as the liquid level. After staying for a period of time, it rises again with the liquid level and enters the variable cross-section filtration zone. This operation is repeated and the liquid level is always kept below the permeable plate to achieve self-cleaning of the lightweight filter material.

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