An annular vertical internal loop water treatment reactor and method

Abstract

The present application belongs to the technical field of water treatment, and particularly relates to a kind of annular vertical internal circulation water treatment reactor and method. The reactor comprises a reactor shell, a center ring shell, an annular partition, an aerobic reaction zone, an anaerobic reaction zone, an anoxic reaction zone, an aeration mechanism, a hollow fiber membrane assembly, a gradually expanding throat, a water inlet / return sludge mixing zone, a sedimentation / filter material self-dispersing zone, a variable cross-section filtration zone, a first and second annular sludge settling zone. The present application changes the device structure and internal hydraulic action mode, uses the air-lift effect of aeration to form a self-circulating vertical flow in the anoxic reaction zone and the aerobic reaction zone; uses a light filter layer and adopts a variable cross-section upward flow anaerobic biological filter layer to achieve self-dispersing and cleaning effect of the filter layer, thereby reducing water consumption and energy consumption; uses the membrane separation effect of MBR to improve the stability of the effluent water quality. The reactor of the present application realizes an optimal ratio of 1:3:5 of the anaerobic / anoxic / aerobic reaction zones.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to an annular vertical internal circulation water treatment reactor and method. Background Technology

[0002] With increasingly stringent wastewater discharge standards, especially the removal of nutrient indicators such as nitrogen and phosphorus from wastewater, which has become an important aspect of biological wastewater treatment, the A / A / O process is a typical biological nitrogen and phosphorus removal process that has been widely used in wastewater treatment facilities of different sizes.

[0003] The A / A / O process (anaerobic-anoxic-aerobic combined process) generally consists of three reaction zones: an anaerobic zone, an anoxic zone, and an aerobic zone. The anaerobic zone's function is to convert some large organic molecules in the raw water into small volatile fatty acids (VFAs) that are easily treated aerobically through hydrolysis and acidification, thereby improving the biochemical performance of the wastewater. Simultaneously, the metabolic characteristics of polyphosphate-accumulating bacteria in the anaerobic zone can be utilized to hydrolyze intracellular polyphosphates into orthophosphates, releasing them into the water to obtain energy for survival. The anoxic zone's main function is to carry out denitrification reactions using organic carbon sources in the wastewater under the action of denitrifying bacteria. The nitrate nitrogen in the denitrification reaction comes from the reflux liquid from the aerobic zone, while the carbon source is obtained by adding organic matter such as methanol. The BOD and nitrate nitrogen removal efficiency in the anoxic zone depends on the reflux ratio of the supernatant from the aerobic zone. The effluent from the anoxic zone then enters the aerobic zone. The main function of the aerobic zone is to remove BOD from the water and nitrify ammonia nitrogen. At the same time, polyphosphate-accumulating bacteria remove phosphorus from the water by absorbing large amounts of phosphorus in an aerobic environment.

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

[0005] Currently, small-scale decentralized wastewater treatment often faces significant fluctuations in raw water flow. For example, rural small-scale wastewater treatment facilities experience large variations in wastewater flow throughout the day, while decentralized wastewater treatment facilities in tourist areas exhibit significant differences in water volume between peak and off-peak seasons, sometimes even remaining in a state of no treatment for extended periods. However, existing small-scale integrated wastewater treatment equipment is mostly a simple reduction in size of the A / A / O process, retaining the linear flow pattern of the original process in form and structure. Furthermore, sludge and wastewater return are often pumped, leading to the following main problems in the actual operation of existing small-scale decentralized wastewater treatment facilities:

[0006] (1) The process facilities are generally arranged in a horizontal straight line, resulting in a large overall equipment footprint.

[0007] (2) The sludge return and supernatant return of small sewage treatment facilities are carried out 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 sewage treatment facilities. However, conventional downflow filtration is prone to clogging, which requires a large amount of clean water for backwashing, increasing water and energy consumption.

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

[0010] To address the above issues, existing equipment uses membrane technology for solid-liquid separation of effluent, replacing sedimentation processes and thus improving the stability of effluent quality. However, since membrane technology itself is only a highly efficient solid-liquid separation method, its denitrification effect must be combined with the wastewater denitrification treatment process to meet effluent quality standards. Therefore, only by organically combining membrane technology with biological treatment to form the MBR process can the problem of operational stability in wastewater treatment be effectively solved.

[0011] Existing conventional MBR processes only use membrane technology for solid-liquid separation. While this greatly improves separation efficiency, it does not effectively simplify the operation and management of small-scale decentralized wastewater treatment plants. Furthermore, during the nitrification and denitrification processes, the return of sludge and wastewater usually requires mechanical pumps, making it difficult to widely apply existing small-scale wastewater treatment equipment to unattended operating conditions.

[0012] This invention addresses the problems existing in the above-mentioned small-scale A / A / O treatment equipment by innovating the reactor structure and operation method, enabling it to achieve a low-maintenance, unattended operation while ensuring the quality of the effluent, thus meeting the needs of a large number of small-scale decentralized sewage treatment projects. Summary of the Invention

[0013] This invention discloses a ring-shaped vertical internal circulation water treatment reactor and method. Addressing the problems described in the background section, this invention modifies the equipment structure and internal hydraulic action, utilizing the airlift effect of aeration to create a vertical flow self-circulation in the anoxic and aerobic reaction zones. By employing a lightweight filter media layer and a variable cross-section upflow anaerobic biological filter layer, a self-dispersing and cleaning effect is achieved, reducing water and energy consumption. The membrane separation effect of an MBR (Membranes in Bioreactor) improves the stability of the effluent quality. The reactor of this invention achieves an optimized ratio of 1:3:5 between the anaerobic / anoxic / aerobic reaction zones.

[0014] To achieve the above objectives, the technical solution of this invention is as follows:

[0015] A ring-shaped vertical internal circulating water treatment reactor includes: a reactor shell, a central ring shell located in the middle of the reactor shell, and an annular partition between the central ring shell and the reactor shell. The central ring shell forms a variable cross-section filtration zone with a larger lower cross-sectional diameter and a smaller upper cross-sectional diameter. This variable cross-section filtration zone is filled with lightweight filter media, on the outer surface of which anaerobic microorganisms grow, creating an anaerobic reaction zone. An anoxic reaction zone is formed between the central ring shell and the annular partition, while an aerobic reaction zone is formed between the annular partition and the reactor shell. The bottom of the annular partition connects the anoxic and aerobic reaction zones through several evenly distributed through-holes around its axis. An aeration mechanism is provided at the bottom of the aerobic reaction zone, driving vertical water circulation between the anoxic and aerobic reaction zones via the aeration mechanism. A hollow fiber membrane module is installed inside the aerobic reaction zone. Aerobic microorganisms grow on the surface. The top of the hollow fiber membrane module is connected to a clear water tank via an outlet pipe. A vacuum pump is installed on the outlet pipe. A first annular sludge settling zone is formed at the bottom of the aerobic reaction zone. The bottom of the central ring shell extends downward and forms a sedimentation / filter media self-dispersion zone and an influent / return sludge mixing zone from top to bottom. A second annular sludge settling zone is formed around the outer periphery of the influent / return sludge mixing zone. A gradually expanding throat is provided in the middle of the influent / return sludge mixing zone. The upper end of the gradually expanding throat is funnel-shaped, and the lower end is a connecting pipe. The bottom end of the connecting pipe penetrates the bottom of the central ring shell and is connected to the raw water tank via an influent pipe. A booster pump is installed on the influent pipe. The connecting pipe is connected to the first annular sludge settling zone via a sludge return pipe. The second annular sludge settling zone is connected to a sludge tank via a sludge pipe. 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 central annular shell includes a second annular shell located at the top and a frustum-shaped shell integrally connected to the bottom end of the second annular shell. The small-diameter end of the frustum-shaped shell is sealed and fixedly connected to the bottom end of the second annular shell. An inwardly inclined annular plate is integrally connected to the bottom of the reactor shell. The annular plate is opposite to the side wall of the frustum-shaped shell, and the bottom end of the annular plate is sealed and fixedly connected to the bottom end of the frustum-shaped shell. The inclination angle of the annular plate and the side wall of the frustum-shaped shell is 60°. The annular plate and the outer wall of the frustum-shaped shell form a first annular sludge settling zone.

[0018] Preferably, the aeration mechanism includes a blower, an aeration pipe, and an aeration head. The aeration pipe surrounds the annular partition and is located in the aerobic reaction zone below the hollow fiber membrane module. 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, the sludge return pipe is a U-shaped structure, the top of the U-shaped structure penetrates 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 settling zone, and the top of the U-shaped structure is also connected to a siphon breaking pipe.

[0020] Preferably, the upper part of the central ring shell is provided with a permeable plate, and a number of water collection caps are evenly distributed on the permeable plate. The lightweight filter media is a hollow plastic ball with a diameter of 2-4 mm. The lightweight filter media fills the second ring shell below the permeable plate and partially fills the frustum-shaped shell. The sedimentation / filter media self-dispersion zone constitutes the dispersion space of the lightweight filter media. The size of the sedimentation / filter media self-dispersion zone satisfies the following condition: after the lightweight filter media enters the dispersion space from the variable cross-section filtration zone, the spacing between the filter media increases, so that the sludge and impurities entrained between the filter media settle.

[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. The outer surface of the settling plate and the inner wall of the central ring shell form a second annular sludge settling zone.

[0022] A method for self-cleaning lightweight filter media in an annular vertical internal circulating water treatment reactor includes: during periods without wastewater treatment, the booster pump stops, and the lightweight filter media descends with the water level into the sedimentation / filter media self-dispersion zone. Due to the increased gaps between the filter media, sludge and impurities between the filter media settle into the second annular sludge settling zone due to their own gravity. When the liquid level in the central ring shell drops to the permeable plate, the siphon breaking pipe automatically introduces air to prevent wastewater from the first annular sludge settling zone from entering the sedimentation / filter media self-dispersion zone due to the siphon effect of the sludge return pipe.

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

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

[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 wastewater can automatically circulate vertically between the aerobic and anoxic reaction zones. This eliminates the need for a reflux pump, simplifies the operation and management of small-scale wastewater treatment facilities, and reduces energy consumption.

[0026] Secondly, it solves the problem of clogging in anaerobic biological filter layers. Conventional downflow anaerobic filter layers become severely clogged after a certain period of operation due to the deposition and compaction of impurities, making them difficult to clean. This invention uses lightweight filter media as the anaerobic biological carrier, changing the downflow to upflow, and employing a variable cross-section upflow structure. 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 wastewater treatment stage, the filter layer descends with the water flow to the gradually expanding space (sedimentation / filter media self-dispersion zone), allowing the filter media layer to automatically disperse, and impurities and sludge trapped between particles to automatically detach and separate. This solves the clogging problem of biological filter layers.

[0027] Third, it solves the problem of carbon source replenishment. This invention places the anaerobic reaction zone and the anoxic reaction zone adjacent to each other. The carbon source in the effluent of the anaerobic reaction zone can be directly used as the carbon source for denitrification in the anoxic reaction zone, thus eliminating the need for external carbon source replenishment.

[0028] Fourth, it solves the problem of automatic sludge return. This invention adopts a gradually expanding inlet mixing zone with a Venturi tube structure in the inlet area. By setting up a gradually expanding throat, a negative pressure suction effect can be generated by the inlet water pressure to automatically suck the remaining sludge at the bottom of the anoxic / aerobic zone into the inlet mixing zone and mix it with the raw water. This achieves the goal of automatic sludge return without the power of a return pump in the A / A / O process. This suction effect can also be controlled by adjusting the inlet water flow rate, without the need for complex automatic control facilities.

[0029] Fifth, a membrane module mainly composed of hollow fiber membranes was installed in the aerobic reaction zone to form an MBR reactor. The high-efficiency separation of the membrane ensured the quality of the effluent, solving the operational stability and effluent quality issues of small-scale decentralized wastewater treatment facilities. Attached Figure Description

[0030] Figure 1 This is a front view of the structure of the present invention during normal operation.

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

[0032] Figure 3 This is a schematic diagram illustrating the self-cleaning principle of lightweight filter media in the absence of wastewater treatment according to the present invention.

[0033] In the diagram: 1. Reactor shell; 2. Annular baffle; 3. Central ring shell; 4. Triangular weir; 5. Permeable plate; 6. Water collection cap; 7. Sludge return pipe; 8. Hollow fiber membrane module; 9. Lightweight filter media; 10. Aeration head; 11. Aeration pipe; 12. Guide block; 13. Gradually expanding throat; 14. Vacuum pump; 15. Booster pump; 16. Inlet valve; 17. Sludge discharge valve; 18. Inlet pipe; 19. Sludge pipe; 20. 21. Outlet pipe; 22. Siphon breaking pipe; 23. Blower; 24. Raw water tank; 25. Clear water tank; 26. Sludge tank; 01. Inlet / Return sludge mixing zone; 02. Sedimentation / Filter media 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 Implementation

[0034] The following description is merely 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 within the scope of protection of the present invention.

[0035] The following embodiments can be understood as illustrating a part of the structure or method of the present invention individually, or as combining the embodiments to explain the broader structure or method of the present invention.

[0036] Example 1

[0037] A ring-shaped vertical internal circulating water treatment reactor, such as Figure 1-3As shown, the reactor includes: a reactor shell 1, a central ring shell 3 located in the middle of the reactor shell 1, and an annular partition 2 located between the central ring shell 3 and the reactor shell 1. The central ring shell 1 forms a variable cross-section filtration zone 03 with a larger lower cross-sectional diameter and a smaller upper cross-sectional diameter. The variable cross-section filtration zone 03 is filled with lightweight filter media 9, and anaerobic microorganisms grow on the outer surface of the lightweight filter media 9, thus forming an anaerobic reaction zone 04. The central ring shell 3 and the annular partition 2 form an anoxic reaction zone 05, and the annular partition 2 and the reactor shell 1 form an aerobic reaction zone 06. The bottom of the annular partition 2 connects the anoxic reaction zone 05 and the aerobic reaction zone 06 through several through holes evenly distributed around its axis. The bottom of the aerobic reaction zone 06 is equipped with an aeration mechanism, and the anoxic reaction zone 05 and the aerobic reaction zone 06 are connected by water circulation driven by the aeration mechanism. The aerobic reaction zone 06 is equipped with a hollow fiber membrane module 8, and aerobic microorganisms grow on the surface of the hollow fiber membrane module 8. The hollow fiber membrane module 8 is connected to a clear water tank 24 via an outlet pipe 20 at its top. A vacuum pump 14 is installed on the outlet pipe 20. A first annular sludge settling zone 08 is formed at the bottom of the aerobic reaction zone 06. The bottom end of the central ring shell 3 extends downward and forms a sedimentation / filter media self-dispersion zone 02 and an influent / return sludge mixing zone 01 from top to bottom. The outer periphery of the influent / return sludge mixing zone 01 forms a second annular sludge settling zone 07. The influent / return sludge mixing zone 01 contains... The unit is equipped with a gradually expanding throat 13, the upper end of which is flared and the lower end is a connecting pipe. The bottom end of the connecting pipe passes through the bottom of the central ring shell 3 and is connected to the raw water tank 23 through the water inlet pipe 18. The water inlet pipe 18 is equipped with a booster pump 15. The connecting pipe is connected to the first annular sludge settling zone 08 through a sludge return pipe 7. The second annular sludge settling zone 07 is connected to a sludge tank 25 through a sludge pipe 19. The top of the central ring shell 3 is equipped with a triangular water distribution weir 4.

[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 central annular shell 3 includes a second annular shell located at the top and a frustum-shaped shell integrally connected to the bottom end of the second annular shell. The small diameter end of the frustum-shaped shell is sealed and fixedly connected to the bottom end of the second annular shell. An inwardly inclined annular plate 09 is integrally connected to the bottom of the reactor shell. The annular plate 09 is opposite to the side wall of the frustum-shaped shell, and the bottom end of the annular plate 09 is sealed and fixedly connected to the bottom end of the frustum-shaped shell. The inclination angle of the annular plate 09 and the side wall of the frustum-shaped shell is 60°. The annular plate 09 and the outer wall of the frustum-shaped shell form a first annular sludge settling zone 08.

[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 located in the aerobic reaction zone 06 below the hollow fiber membrane module 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 vent pipe that passes 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. The sludge return pipe 7 is a U-shaped structure. The top of the U-shaped structure penetrates 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 settling zone 08. The top of the U-shaped structure is also connected to the siphon destruction pipe 21.

[0046] Example 6

[0047] like Figure 1 , 2 As shown in Figure 3, the upper part of the central ring shell 3 is provided with a permeable plate 5, and several water collection caps 6 are evenly distributed on the permeable plate 5. The lightweight filter media 9 is a hollow plastic ball with a diameter of 2-4 mm. The lightweight filter media 9 is filled in the second ring shell below the permeable plate 5 and partially filled in the frustum-shaped shell. The sedimentation / filter media self-dispersion zone 02 constitutes the dispersion space of the lightweight filter media 9. The size of the sedimentation / filter media self-dispersion zone 02 satisfies the following condition: after the lightweight filter media 9 enters the dispersion space from the variable cross-section filtration zone, the spacing between the filter media increases, so that the sludge and impurities entrained between the filter media settle.

[0048] Example 7

[0049] like Figure 1As shown, a guide block 12 is provided above the gradually expanding throat 13, and a settling plate 010 with an inverted "V" shaped cross-section is surrounded around the outer periphery of the gradually expanding throat 13. The outer surface of the settling plate 010 and the inner wall of the central ring shell 3 form a second annular sludge settling zone 07.

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

[0051] Example 8

[0052] Based on the above embodiments, this embodiment discloses a method for self-cleaning of lightweight filter media in an annular vertical internal circulating water treatment reactor, such as... Figure 1-3 As shown, during periods without wastewater treatment, the booster pump 15 stops, and the lightweight filter media 9 descends with the water level into the sedimentation / filter media self-dispersion zone 02. Due to the increased gaps between the filter media, the sludge and impurities between the filter media settle into the second annular sludge settling zone 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 introduces air to prevent the sludge return pipe 7 from causing the wastewater in the first annular sludge settling zone 08 to enter the sedimentation / filter media self-dispersion zone 02 due to the siphon effect.

[0053] In this embodiment, the siphon destruction tube 21 is existing technology, and its structure and principle are detailed in the existing technology disclosure.

[0054] Example 9

[0055] like Figure 1-3 As shown, after the lightweight filter media 9 enters the sedimentation / self-dispersion zone 02 as the water level drops, the booster pump 15 starts and stops intermittently. During this process, the lightweight filter media 9 enters the variable cross-section filtration zone 03 as the liquid level rises, and then falls back into the sedimentation / self-dispersion zone 02 as the liquid level falls. After staying for a period of time, it enters the variable cross-section filtration zone 03 again as the liquid level rises. This process is repeated while always keeping the liquid level below the permeable plate 5, thus achieving self-cleaning of the lightweight filter media 9.

[0056] This embodiment provides another way to achieve self-cleaning. Based on embodiment 8, a small amount of raw water is reserved at the end of the sewage treatment process. Through repeated rising and pressing, falling and dispersing of the lightweight filter media, and continuous sludge settling for a certain period of time during the dispersion process, the sludge in the lightweight filter media settles into the second annular sludge settling zone, thereby achieving self-cleaning of the lightweight filter media.

[0057] The working principle of this invention is described in detail below:

[0058] 1. During the wastewater treatment process, the raw water, i.e. the wastewater, enters the gradually expanding throat through the inlet pipe. The Bernoulli principle is used to generate a suction effect, which causes the sludge in the first annular sludge settling zone to be sucked through the sludge return pipe to the connecting pipe. Then, it flows out from the top of the gradually expanding throat along with the wastewater, thereby achieving the mixing of wastewater and sludge.

[0059] 2. After being guided by the guide block 12, the mixed wastewater is evenly distributed in the sedimentation / filter media self-dispersion zone 02. Due to the sudden expansion of the cross-section of the water outlet from the gradually expanding throat, the wastewater flow rate drops rapidly, which can promote the sedimentation and separation of suspended solids in the wastewater in this area. The separated sludge enters the second annular sludge settling zone 07, and the separated wastewater flows upward into the anaerobic reaction zone 04.

[0060] 3. The upward flow of sewage pushes the lightweight filter media 9 into the filling position, where they are squeezed together to form a variable cross-section filtration zone 03. Anaerobic microorganisms growing on the surface of the lightweight filter media 9 are used for anaerobic hydrolysis treatment.

[0061] 4. After the anaerobic reaction zone 04, the effluent passes through a permeable plate with a water collection cap to the top of the central ring shell, and is then evenly distributed to the anoxic reaction zone through a triangular distribution weir 4. In this space, the treated raw water from the anaerobic reaction zone and the circulating water from the aerobic reaction zone are fully mixed to form the anoxic reaction zone, completing the denitrification process. Since the raw water in the anaerobic reaction zone has sufficient carbon source, and the mixed liquor in the aerobic reaction zone circulates continuously with the anoxic reaction zone under the action of aeration and air lifting, a vertical anoxic-aerobic distribution balance is formed between the anoxic reaction zone and the aerobic reaction zone, achieving the purpose of continuous and stable denitrification.

[0062] 5. The effluent from the anoxic reaction zone continuously enters the aerobic reaction zone 06 through the through hole. A hollow fiber membrane module is installed in the aerobic reaction zone. The vacuum pump 14 continuously draws the clean water out to the clean water tank and retains the activated sludge in the aerobic reaction zone. The settled sludge enters the first annular sludge settling zone and automatically enters the sedimentation / filter media self-dispersion zone 02 under the suction of the sludge return pipe. Then it settles into the second annular sludge settling zone and is discharged to the sludge tank through the sludge pipe 19.

[0063] 6. When the amount of wastewater in the raw water tank drops to a certain height (detectable by a level gauge), the booster pump stops. At this time, the water level in the anaerobic reaction zone automatically drops. The lightweight filter media 9, due to its own gravity, drops with the water level and automatically disperses within the sedimentation / filter media self-dispersion zone 02. Impurities and sludge trapped between the filter media automatically settle into the second annular sludge settling zone due to gravity, achieving self-cleaning of the lightweight filter media. During this process, to prevent wastewater from the first annular sludge settling zone from being siphoned into the sedimentation / filter media self-dispersion zone 02 through the sludge return pipe due to the drop in water level, a siphon breaking pipe 21 is installed at the top of the sludge return pipe. When the water level drops to the permeable plate 5, air automatically enters the siphon breaking pipe, causing the siphon effect to fail and blocking the water flow in the aerobic reaction zone. After the water supply resumes, the lightweight filter media automatically resets under the action of the rising water flow, forming a variable cross-section filtration zone.

[0064] 7. The influent / return sludge mixing zone of this invention is located in the middle area of ​​the bottom of the reactor and is equipped with a gradually expanding throat-shaped pipe. A connecting pipe at the lower part of the throat-shaped pipe is connected to the sludge return end. When raw water enters under pressure from a booster pump, a negative pressure suction effect is generated within the connecting pipe, allowing the sludge from the first annular sludge settling zone to return and mix with the raw water. The mixed sludge can hydrolyze large-molecule organic matter and recalcitrant organic matter in the raw water under anaerobic conditions, forming small-molecule organic matter that is easily bio-oxidized, thus promoting the efficiency of subsequent biological treatment. Simultaneously, this mixing is beneficial for improving sludge settling performance.

[0065] 8. A guide block is provided in the sedimentation / filter media self-dispersion zone 02 to dissipate energy and guide the effluent from the gradually expanding throat. After the guide block, the mixed wastewater experiences a sudden increase in cross-sectional area and a rapid decrease in upward flow velocity, thus creating a relatively static separation environment. Impurities in the raw water can separate from the water due to inertia, achieving a primary sedimentation effect on the raw water, which is beneficial for subsequent anaerobic biological treatment. As mentioned above, this area is also used for self-cleaning of the lightweight filter media at the tail end of the wastewater treatment process.

[0066] 9. The variable cross-section filtration zone is composed of a second annular shell and a frustum-shaped shell. The cross-sectional area of ​​the frustum-shaped shell gradually decreases from bottom to top. Since the influent flow rate remains constant, the cross-sectional area decreases. According to the formula Q=A·υ, the water flow velocity will gradually increase, causing the lightweight filter media in this area to be automatically compressed under hydraulic action, forming an anaerobic reaction zone filtration layer.

[0067] 10. The anoxic reaction zone is connected to the anaerobic reaction zone via a triangular weir and to the aerobic reaction zone via the top of an annular baffle. The volume ratio of the anaerobic reaction zone to the anoxic reaction zone to the aerobic reaction zone is 1:3:5. The influent to the anaerobic reaction zone contains a large amount of carbon source, which automatically provides carbon source for denitrification in the anoxic reaction zone, thus eliminating the need for external carbon source. Through the airlift effect of aeration in the aerobic reaction zone, an internal water circulation is formed vertically between the anoxic and aerobic reaction zones, resulting in a small footprint and a stable vertical structure. The nitrates produced by oxidation in the aerobic reaction zone can be continuously supplied to the denitrifying bacteria in the anoxic reaction zone, forming a continuous and stable denitrification effect.

[0068] 11. The first annular sludge settling zone is a 60-degree ring. O A sloping, annular sludge collection zone is formed, with hollow fiber membrane modules installed in the aerobic reaction zone, creating an aerobic MBR reactor. This reactor replaces the secondary sedimentation tank to achieve sludge-water separation and ensures the stability of the effluent quality. The hollow fiber membrane module—the MBR membrane module—uses a vacuum pump to extract effluent, while the sludge in the aerobic reaction zone is retained, achieving highly efficient sludge-water separation.

[0069] 12. A ring-shaped aeration pipe is installed at the bottom of the aerobic reaction zone. This provides oxygen for biodegradation in the aerobic reaction zone and, through the airflow, promotes vertical internal circulation, achieving spatial distribution of anoxic / aerobic areas and realizing biological nitrogen removal through nitrification / denitrification. Biodegradation in the aerobic reaction zone effectively reduces BOD and ammonia nitrogen in the water. Further separation by the MBR membrane module ensures stable effluent quality meeting standards. Sludge at the bottom of the aerobic reaction zone is automatically returned to the sedimentation / filter media self-dispersion zone 02 via a U-shaped sludge return pipe connected to a gradually expanding throat, achieving sludge return without the need for a return pump.

[0070] 13. The gradually expanding throat is surrounded by an inverted "V"-shaped settling plate. Due to the shielding effect of the settling plate, the sludge settled in the second annular sludge settling zone is not affected by the influent flow. During the self-cleaning of the anaerobic biological filter layer, the impurities trapped between the filter layers will also automatically settle in the second annular sludge settling zone. The annular bucket-shaped structure of the second annular sludge settling zone facilitates the collection and removal of sludge. The sludge settled in the second annular sludge settling zone is periodically removed through the sludge pipe, maintaining the effective operation of the reactor's biological system.

[0071] Experimental example:

[0072] The aforementioned "Annular Vertical Internal Circulating Water Treatment Reactor" was used to treat domestic sewage from a residential community. The treatment capacity was 500 L / h, and the results are shown in Table 1.

[0073] As shown in Table 1, the reactor effectively removes BOD, SS, and ammonia nitrogen from the water. The reactor achieves a BOD removal rate of approximately 97%, a SS removal rate of approximately 99%, and ammonia nitrogen removal rate of approximately 94%. The effluent meets the Class A standard.

[0074] The reactor can be operated automatically by hydraulic regulation.

[0075] Table 1. Effect of the reactor on wastewater treatment in the residential area

[0076]

Claims

1. An annular vertical internal loop water treatment reactor characterized by comprising: The reactor shell, the center ring shell body arranged in the middle part of the reactor shell, the annular partition plate arranged between the center ring shell body and the reactor shell, the center ring shell body is formed in the variable cross-section filter area with large lower cross-section diameter and small upper cross-section diameter, the variable cross-section filter area is filled with light filter material, the outer surface of the light filter material grows anaerobic microorganisms, and the variable cross-section filter area forms an anaerobic reaction area; the center ring shell body and the annular partition plate constitute an anoxic reaction area, the annular partition plate and the reactor shell constitute an aerobic reaction area, the annular partition plate bottom is connected with the anoxic reaction area and the aerobic reaction area through a plurality of through holes uniformly distributed around the axis, the bottom of the aerobic reaction area is provided with an aeration mechanism, the anoxic reaction area and the aerobic reaction area are driven by the aeration mechanism to circulate water flow, the inside of the aerobic reaction area is provided with a hollow fiber membrane assembly, the surface of the hollow fiber membrane assembly grows aerobic microorganisms, the top of the hollow fiber membrane assembly is connected with a clean water tank through a water outlet pipe, a vacuum pump is arranged on the water outlet pipe, the bottom of the aerobic reaction area forms a first annular sludge settling area, the bottom end of the center ring shell body extends downward and sequentially forms a precipitation / filter material self-dispersing area, a water inlet / return sludge mixing area from top to bottom, the outer periphery of the water inlet / return sludge mixing area constitutes a second annular sludge settling area, the middle part of the water inlet / return sludge mixing area is provided with a converging type throat, the upper end of the converging type throat is in the shape of a horn mouth, and the lower end is in the shape of a connecting pipe, the bottom end of the connecting pipe penetrates through the bottom of the center ring shell body and is connected with the raw water tank through a water inlet pipe, a booster pump is arranged on the water inlet pipe, the connecting pipe and the first annular sludge settling area are connected through a sludge return pipe, the second annular sludge settling area is connected with a sludge tank through a sludge pipe, and the top end of the center ring shell body is provided with a triangular water distribution weir. The top of the center ring shell body is higher than the top of the annular partition plate, the sludge return pipe is in a U-shaped structure, the top of the U-shaped structure penetrates through the upper part of the side wall of the center ring shell body, one end of the sludge return pipe is connected with the connecting pipe, the other end is connected with the first annular sludge settling area, and the top of the U-shaped structure is further connected with a siphon breaking pipe.

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

5.

3. A vertical, internally circulating, annular water treatment reactor according to claim 2, characterized in that The reactor shell is a first annular shell, the center ring shell body includes a second annular shell located at the upper part and a circular truncated cone shell body integrally connected to the bottom end of the second annular shell, the small-diameter end of the circular truncated cone shell body is sealingly and fixedly connected with the bottom end of the second annular shell, the bottom of the reactor shell is integrally connected with an annular plate inclined to the inside, the annular plate is opposite to the side wall of the circular truncated cone shell body, the bottom end of the annular plate is sealingly and fixedly connected with the bottom end of the circular truncated cone shell body, the inclination angles of the annular plate and the side wall of the circular truncated cone shell body are both 60°, and the annular plate and the outer wall of the circular truncated cone shell body constitute a first annular sludge settling area.

4. A vertical, internally circulating, annular water treatment reactor according to claim 3, characterized in that The aeration mechanism comprises a blower, an aeration pipe and an aeration head.

5. A vertical, internally circulating, annular water treatment reactor according to claim 4, characterized in that The upper portion of the central ring shell is provided with a water permeable plate, and the water permeable plate is uniformly provided with a plurality of water collecting caps.

6. A vertical, internally circulating, annular water treatment reactor according to claim 5, characterised in that The upper portion of the central ring shell is provided with a water permeable plate, and the water permeable plate is uniformly provided with a plurality of water collecting caps.

7. A method of self-cleaning of light weight filter media of a ring-shaped vertical internal loop water treatment reactor according to claim 6, characterized in that it comprises: The upper portion of the central ring shell is provided with a water permeable plate, and the water permeable plate is uniformly provided with a plurality of water collecting caps.

8. A method of self-cleaning of light weight filter media of a ring-shaped vertical internal loop water treatment reactor according to claim 7, characterized in that, The upper portion of the central ring shell is provided with a water permeable plate, and the water permeable plate is uniformly provided with a plurality of water collecting caps. The upper portion of the central ring shell is provided with a water permeable plate, and the water permeable plate is uniformly provided with a plurality of water collecting caps.

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