Self-cultivation system of aerobic granular sludge under continuous flow state and application thereof

Abstract

The application discloses a kind of self-cultivation system of aerobic granular sludge under continuous flow state and application thereof, belong to water treatment technical field.The system includes membrane bioreactor main body, water inlet component, drainage component and aeration component;Wherein, membrane bioreactor main body includes outer cylinder and inner cylinder;Inner cylinder includes aerobic granular sludge aerobic reaction zone, membrane separation zone, aeration zone and be provided in the sludge storage area of inner cylinder bottom, membrane separation zone is provided with the membrane component of sewage treatment, and the inner cylinder side wall of aeration zone is equipped with circulation port;Sewage enters outer cylinder from the top of aerobic granular sludge aerobic reaction zone, and from circulation port into aeration zone;Aeration component provides gas for aeration zone and reaction zone;Water inlet component is communicated with outer cylinder;Drainage component is communicated with membrane component.The system is not blocked in the process of hydraulic circulation, and circulation speed is fast;Granulation speed is fast, and particle can stably exist for four months before entering cleavage period, with excellent stability.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology. More specifically, it relates to a self-cultivation system for aerobic granular sludge in continuous flow and its application. Background Technology

[0002] Currently, the vast majority of wastewater treatment plants use activated sludge processes and their modified technologies to remove pollutants and substances such as nitrogen and phosphorus. However, with long-term operation, many drawbacks have begun to emerge. For example, a large amount of excess sludge is generated during the treatment process, and this amount increases with the volume of wastewater treated; it requires a large area, resulting in low land resource utilization efficiency; it has low volumetric loading capacity, poor resistance to shock loads, and is prone to filamentous bacterial bulking.

[0003] Aerobic granular sludge (AGS) technology utilizes granular aggregates formed by the self-aggregation of microorganisms in an aerobic environment to remove pollutants from wastewater through biochemical reactions. Compared to suspended activated sludge, aerobic granular sludge, being a spherical microbial community formed by microbial self-aggregation, inherently possesses stratified zones with progressively advancing aerobic, anoxic, and anaerobic zones, giving it a greater advantage in water purification. However, this technology also has some areas that require further improvement, such as shortening the cultivation period and enhancing the stability of aerobic granular sludge.

[0004] Membrane bioreactors (MBRs) are wastewater treatment systems that combine biological treatment technology with membrane separation technology. They can provide higher quality effluent, reduce excess sludge production, and facilitate operation and management. However, they also face some challenges. To maintain normal membrane operation and ensure effluent quality, a stable energy supply must be provided to the MBR system, which means higher operating costs. Furthermore, membrane fouling is a common problem during MBR operation. As operating time increases, sludge and contaminants may accumulate on the membrane surface, leading to a decrease in membrane flux and requiring regular cleaning and maintenance to restore membrane performance.

[0005] The prior art CN118239600A discloses a hydraulically driven continuous flow aerobic granular sludge-membrane filtration integrated device. This device has many power-consuming components, and the cultivation cycle for aerobic granular sludge is relatively long, requiring 30 days. In addition, the anaerobic zone is equipped with multiple guide plates inclined at a 45° angle longitudinally. During the hydraulic circulation process, the obstruction of the structure results in a slow circulation velocity and is prone to forming circulation dead zones. After the wastewater is purified, the water quality can only meet the Class IV surface water standard. Summary of the Invention

[0006] Based on the aforementioned existing technical problems, the primary objective of this invention is to provide a self-cultivation system for aerobic granular sludge in a continuous flow state.

[0007] Another object of the present invention is to provide a wastewater treatment method.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution:

[0009] This invention claims protection for a self-cultivation system for aerobic granular sludge in a continuous flow state, comprising:

[0010] The membrane bioreactor body includes an outer cylinder and an inner cylinder. The upper half of the inner cylinder is a reaction zone, and the lower half is an aeration and sludge storage zone. The reaction zone includes an aerobic granular sludge aerobic reaction zone and a membrane separation zone. The aeration and sludge storage zone is an aeration zone at one end near the reaction zone and a sludge storage zone at the other end away from the reaction zone. The top of the aerobic granular sludge aerobic reaction zone is connected to the outer cylinder. A circulation port is provided on the side wall of the inner cylinder of the aeration zone. Wastewater can enter the outer cylinder from the top of the aerobic granular sludge aerobic reaction zone and enter the aeration zone from the circulation port. The membrane separation zone is equipped with a membrane module for treating wastewater.

[0011] An aeration assembly provides gas to the aeration zone and the reaction zone;

[0012] A water inlet assembly, which is connected to the outer cylinder;

[0013] A drainage assembly, which is connected to the membrane assembly.

[0014] This invention combines aerobic granular sludge (AGS) technology with membrane bioreactor (MBR) to provide a self-cultivation system for aerobic granular sludge in a continuous flow state. It adopts an unobstructed vertical circulation mode. In the aerobic zone, aeration provides water-driven upward flow, while in the anoxic-anaerobic zone, the wastewater is driven vertically downward by its own gravity. After passing through the circulation port and being screened by aeration, the larger dead sludge blocks enter the columnar sludge storage area for sedimentation, while the wastewater is driven upward by aeration to participate in a new cycle.

[0015] During the alternating anaerobic-aerobic-anoxic circulation of sludge driven by aeration, granules can be rapidly formed with the help of hydraulic shear force, and denitrification and phosphorus removal can be carried out simultaneously. There are no obstructions in the hydraulic circulation process, the circulation speed is fast, and there are no dead zones in the circulation. Since the system is a continuous circulation mode, the anoxic-anaerobic zone is relative. Therefore, the dissolved oxygen required in the aerobic zone is lower than the standard value, about 1-1.5 mg / L, and low-power aeration is sufficient. During the cultivation of aerobic granular sludge, there are no other high-energy-consuming sources outside the aeration system, which is more energy-efficient.

[0016] Furthermore, in practical applications, the system provided by this invention can achieve rapid granulation within 13 days, significantly reducing the start-up time of membrane bioreactors. The granules remain stable for four months before entering the pyrolysis phase, with an operating cycle exceeding three months. The effluent quality meets Class I discharge standards, demonstrating excellent stability. The self-cultivation system for aerobic granular sludge under continuous flow conditions provided by this invention features a simple structural design, small footprint, strong resistance to shock loads, and effective reduction of membrane fouling. It can be widely applied in decentralized wastewater treatment scenarios to treat various types of wastewater, showing promising application prospects.

[0017] Preferably, the water inlet assembly includes a water inlet pump, a water inlet pipe, and a water inlet check valve connected in sequence, with one side of the water inlet check valve connected to the outer cylinder.

[0018] Preferably, the drainage assembly includes a water pump and a water pipe connected in sequence, with one end of the water pipe connected to the membrane assembly.

[0019] Preferably, the tops of the outer cylinder and the inner cylinder are open, the inner cylinder is disposed in the inner cavity of the outer cylinder, and the inner cylinder and the outer cylinder are coaxially arranged.

[0020] Preferably, the height-to-diameter ratio of the upper cavity of the membrane bioreactor body is 1.5 to 4:1.

[0021] Preferably, the outer cylinder wall is 10-20 cm higher than the inner cylinder wall.

[0022] Preferably, the inner cavity of the outer cylinder includes, from top to bottom, a connected aerobic granular sludge anoxic-anaerobic reaction zone and a sludge guiding zone, wherein the aerobic granular sludge anoxic-anaerobic reaction zone is connected to the aerobic granular sludge aerobic reaction zone.

[0023] Preferably, the volume ratio of the aerobic reaction zone to the anoxic-anaerobic reaction zone of the aerobic granular sludge is 1:2 to 1:3.

[0024] Preferably, a support portion is provided in the inner cavity of the inner cylinder, and a membrane module frame is placed on the support portion. The membrane module is arranged in the membrane module frame, and the membrane module frame and the membrane module form a membrane separation zone.

[0025] Preferably, the membrane assembly frame can fix 1 to 4 hollow fiber membranes or curtain membranes.

[0026] Preferably, the system further includes a sludge discharge assembly connected to the sludge storage area.

[0027] Preferably, the aeration assembly includes an air source, an aeration check valve, an aeration throttle valve, and a microporous aeration disc assembly connected in sequence; wherein the microporous aeration disc assembly is disposed in the aeration zone.

[0028] Preferably, an aeration guiding device is arranged around the outer wall of the inner cylinder near the upper part of the circulation port, and the aeration guiding device extends toward the outer cylinder. The angle between the direction of the aeration guiding device toward the outer cylinder and the horizontal plane is 30° to 70°.

[0029] Preferably, the length of the aeration guide device is 2 to 5 cm.

[0030] Preferably, the height difference between the upper and lower edges of the circulation port is 8–20 cm.

[0031] Furthermore, the present invention claims protection for a wastewater treatment method in which wastewater is fed into the aforementioned self-cultivation system of aerobic granular sludge in a continuous flow state.

[0032] Specifically, during the wastewater treatment process, the operating temperature of the membrane bioreactor chamber is 10–30°C, the pH of the liquid inside the chamber is 6.0–9.0, and the aeration intensity in the aerobic zone is 0.5–4.2 m³ / s. 3 / h, hydraulic retention time is 2–24h, and effluent flux of the membrane module in the reactor is 5–30 L / m 2 ·h.

[0033] The present invention has the following beneficial effects:

[0034] This invention provides a self-cultivation system for aerobic granular sludge in a continuous flow state. During the alternating anaerobic-aerobic-anoxic circulation of the sludge driven by aeration, aerobic granular sludge can be rapidly formed using hydraulic shear force, simultaneously achieving denitrification and phosphorus removal. The system operates without obstruction from structures during hydraulic circulation, resulting in rapid circulation and no dead zones. It requires a lower dissolved oxygen level than the standard value, allowing for low-power aeration and greater energy efficiency. The system exhibits rapid granulation, and the granules remain stable for four months before entering the pyrolysis phase, demonstrating excellent stability and a long stable operating period. The effluent quality is good, meeting Class I discharge standards. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the self-cultivation system of aerobic granular sludge in continuous flow in Example 1.

[0036] Figure 2 This is a top view of the self-cultivation system of aerobic granular sludge in continuous flow in Example 1.

[0037] Figure 3 This is a top view of the self-cultivation system of aerobic granular sludge in continuous flow in Example 2.

[0038] Figure 4 Optical microscope images of the initial particles, growth particles, and mature particles formed on days 13, 45, and 90 of Example 2.

[0039] Among them, 1-inlet pump, 2-sludge guiding zone, 3-inlet check valve, 4-aerobic granular sludge aerobic reaction zone, 5-membrane separation zone, 6-outlet pump, 7-membrane module, 8-membrane module frame, 9-aerobic granular sludge anoxic-anaerobic reaction zone, 10-reactor support column, 11-aeration check valve, 12-aeration throttling valve, 13-air source, 14-microporous aeration disc assembly, 15-sludge storage zone, 16-sludge discharge port, 17-sludge discharge throttling valve, 18-aeration guiding device, 19-inner cylinder support column, 20-inlet, 21-membrane reactor body, 22-outer cylinder, 23-inner cylinder, 231-circulation port. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0041] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0042] Example 1

[0043] like Figure 1 and 2 As shown, a self-cultivation system for aerobic granular sludge in continuous flow includes a membrane bioreactor body 21, an aeration component, an influent component, a drainage component, and a sludge discharge component.

[0044] In this embodiment, the tops of the outer cylinder 22 and the inner cylinder 23 are open, the inner cylinder 23 is disposed in the inner cavity of the outer cylinder 22, and the inner cylinder 23 and the outer cylinder 22 are coaxially arranged.

[0045] In this embodiment, the outer cylinder 22 is 15cm higher than the inner cylinder 23, and the tops of both the outer cylinder 22 and the inner cylinder 23 are cylindrical in horizontal cross-section.

[0046] In this embodiment, the height-to-diameter ratio of the upper cavity of the membrane bioreactor body 21 is 3:1.

[0047] In this embodiment, the upper half of the inner cylinder 23 is a reaction zone, and the lower half is an aerated sludge storage zone. The reaction zone includes an aerobic granular sludge aerobic reaction zone 4 and a membrane separation zone 5. The end of the aerated sludge storage zone closest to the reaction zone is the aeration zone, and the end furthest from the reaction zone is the sludge storage zone 15. A circulation port 231 is provided on the side wall of the inner cylinder 23 within the aeration zone; wastewater can enter the outer cylinder 22 from the top of the aerobic granular sludge aerobic reaction zone 4 and enter the aeration zone through the circulation port 231.

[0048] In this embodiment, the inner cavity of the outer cylinder 22 includes, from top to bottom, a connected aerobic granular sludge anoxic-anaerobic reaction zone 9 and a sludge guiding zone 2. The aerobic granular sludge anoxic-anaerobic reaction zone 9 is connected to the aerobic granular sludge aerobic reaction zone 4. More specifically, the lower edge of the circulation port 231 at the lower end of the membrane bioreactor body 21 is arc-shapedly connected to the outer cylinder 22 to form the sludge guiding zone 2. The cylinder wall above the arc inflection point of the outer cylinder 22 is parallel to the inner cylinder 23. The bottom end of the inner cylinder 23 below the circulation port 231, except for the sludge discharge port 16, is closed to form a cylindrical sludge storage zone 15.

[0049] In this embodiment, the volume ratio of the aerobic reaction zone 4 of the aerobic sludge granules to the anoxic-anaerobic reaction zone 9 of the aerobic sludge granules is 1:2.

[0050] In this embodiment, an inlet 20 is provided on each of the two sides of the outer cylinder 22; the water inlet assembly includes an inlet pump 1, an inlet pipe and an inlet check valve 3 connected in sequence, and one side of the inlet check valve 3 is connected to the inlet 20 of the outer cylinder 22.

[0051] In this embodiment, a support portion is provided in the inner cavity of the inner cylinder 23, and a membrane module frame 8 is placed on the support portion. The membrane module 7 is disposed within the membrane module frame 8, and the membrane module frame 8 and the membrane module 7 form the membrane separation zone 5. More specifically, the membrane module 7 is a hollow fiber membrane, and the specific number of them is 4.

[0052] In this embodiment, the drainage assembly includes a water pump 6 and a water pipe connected in sequence, with one end of the water pipe connected to the top of the membrane assembly 7.

[0053] In this embodiment, the system also includes a sludge discharge assembly, which includes a sludge discharge port 16, a sludge discharge throttle valve 17, and a sludge discharge pipe. The sludge discharge port 16 is located at the bottom of the inner cylinder 23 and is connected to the sludge storage area 15. Gravity and pressure are used as the driving forces for sludge discharge to discharge the sludge from the sludge discharge port 16.

[0054] In this embodiment, the aeration assembly includes an air source 13, an aeration check valve 11, an aeration throttling valve 12, and a microporous aeration disc assembly 14 connected in sequence. The aeration assembly provides air to the aerobic zone 4, and the aeration directly washes over the membrane assembly 7. At the same time, the aeration also pushes the sludge in the sludge guiding zone 2 into the circulation, and screens out the sludge with larger mass so that it enters the sludge storage zone 15 for sedimentation.

[0055] In this embodiment, an aeration guide device 18 is arranged around the outer wall of the inner cylinder 23 near the upper part of the circulation port 231, and the aeration guide device 18 extends toward the outer cylinder 22. More specifically, in this embodiment, the aeration guide device 18 is a guide plate, which extends toward the outer cylinder at an angle of 45° with the horizontal plane and surrounds the outer wall of the inner cylinder 23 for a length of 3 cm.

[0056] In this embodiment, the area above the circulation port 231 in the inner cylinder 23 is supported by the bottom end of the sludge storage area 15 via the inner cylinder support column 19. The membrane bioreactor body 21 is supported by the reactor support column 10, one end of which is fixed to the outer cylinder 22.

[0057] In this embodiment, the height difference between the upper and lower edges of the circulation port 231 is 14cm.

[0058] The above-mentioned device is used to treat wastewater, and the treatment method includes the following steps:

[0059] (1) Before treating wastewater, sludge should be pre-inoculated. The sludge needs to undergo 12-16 days of aeration acclimatization before inoculation. After inoculation, maintain a high influent load of COD = 1200 mg / L and high aeration of 4.2 m for 4-6 days. 3 / h, to promote the reproduction of filamentous fungi. During the acclimatization period, supplement with a small amount of water to compensate for water loss.

[0060] (2) The inlet pump 1 continuously sends the sewage into the aerobic granular sludge anoxic-anaerobic reaction zone 9.

[0061] (4) The microporous aeration disc group 14 provides gas to the aerobic reaction zone 4 of the aerobic granular sludge. The operating temperature of the reactor chamber is controlled at 25℃, the pH of the liquid inside the chamber is 7, and the aeration intensity of the aerobic zone is 1.5m. 3 / h, hydraulic retention time is 12h, and the effluent flux of membrane module 7 is 20L / m 2 ·h.

[0062] (5) Aeration can directly flush the aerobic reaction zone 4 and membrane separation zone 5 of aerobic granular sludge. Aeration flushing alleviates membrane fouling. The sludge is pushed by aeration to form an alternating anaerobic-aerobic-anoxic circulation in the reactor.

[0063] (6) After being treated by aerobic granular sludge during the circulation process, the wastewater is filtered by membrane module 7 in membrane separation zone 5 and discharged in compliance with standards.

[0064] (7) After aeration and screening, the larger dead mud blocks enter the mud storage area 15 for sedimentation, and are finally discharged through the mud discharge port 16 by gravity and pressure.

[0065] Example 2

[0066] The difference between this embodiment and Embodiment 1 is that: Figure 3 As shown, the top of the outer cylinder 22 is square in horizontal cross-section, and the volume ratio of the aerobic reaction zone 4 of the aerobic sludge granules to the anoxic-anaerobic reaction zone 9 of the aerobic sludge granules is 1:3.

[0067] Example 3

[0068] Wastewater was treated using the self-cultivation system of aerobic granular sludge under continuous flow conditions as described in Example 1. Return sludge from the secondary sedimentation tank of a wastewater treatment plant in Dongguan was taken, aerated and acclimatized for 14 days, and then inoculated into a membrane bioreactor for domestic wastewater treatment. After inoculation, a high influent load was maintained for 5 consecutive days to promote the proliferation of filamentous bacteria, while aeration was increased to promote the formation of aerobic granular sludge.

[0069] The aerobic granular sludge cultivated at each stage in this embodiment is as follows: Figure 4 As shown in the diagram, aerobic granular sludge formed in the early stages of system operation, around day 13. At room temperature, the system operated continuously for the first 60 days without sludge discharge, primarily during the aerobic granular sludge proliferation period, during which the removal rates of chemical oxygen demand (COD) and ammonia nitrogen were both ≥90%. In subsequent operation, the system began discharging sludge every 10 days. During this period, the system stabilized, with an average COD removal rate of 96%, and average removal rates of total nitrogen (TN) and total phosphorus (TP) stabilizing at 85% and 83%, respectively, demonstrating good pollutant removal efficiency. After system stabilization, effluent water quality testing showed COD <20 mg / L, TN <8 mg / L, and TP <0.8 mg / L, meeting the Class I discharge standard.

[0070] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A self-cultivation system for aerobic granular sludge in continuous flow, characterized in that, include: The membrane bioreactor body (21) includes an outer cylinder (22) and an inner cylinder (23). The upper half of the inner cylinder (23) is a reaction zone, and the lower half is an aeration and sludge storage zone. The reaction zone includes an aerobic granular sludge aerobic reaction zone (4) and a membrane separation zone (5). The aeration and sludge storage zone is located at one end near the reaction zone and at the other end away from the reaction zone (15). The top of the aerobic granular sludge aerobic reaction zone (4) is connected to the outer cylinder (22). A circulation port (231) is provided on the side wall of the inner cylinder (23) in the aeration zone. Wastewater enters the outer cylinder (22) from the top of the aerobic granular sludge aerobic reaction zone (4) and enters the aeration zone from the circulation port (231). The membrane separation zone (5) is equipped with a membrane module (7) for treating wastewater. An aeration assembly provides gas to the aeration zone and the reaction zone; A water inlet assembly, which is connected to the outer cylinder (22); A drainage assembly, which is connected to the membrane assembly (7); The inner cavity of the inner cylinder (23) is provided with a support part, on which a membrane module frame (8) is placed, and the membrane module (7) is arranged in the membrane module frame (8). The membrane module frame (8) and the membrane module (7) form a membrane separation zone (5). The lower edge of the loop inlet (231) at the lower end of the membrane bioreactor body (21) is connected to the outer cylinder (22) in an arc shape to form a sludge guiding zone (2). The cylinder wall above the arc inflection point of the outer cylinder (22) is parallel to the inner cylinder (23). The bottom end of the cylinder below the loop inlet (231) of the inner cylinder (23) is closed except for the sludge discharge port (16) to form a columnar sludge storage zone (15). An aeration guide device (18) is arranged around the outer wall of the inner cylinder (23) near the top of the circulation port (231). The aeration guide device (18) extends toward the outer cylinder (22). The aeration guide device (18) is a guide plate. The guide plate extends toward the outer cylinder at an angle of 45° with the horizontal plane and surrounds the outer wall of the inner cylinder (23).

2. The system according to claim 1, characterized in that, The tops of the outer cylinder (22) and the inner cylinder (23) are open, the inner cylinder (23) is disposed in the inner cavity of the outer cylinder (22), and the inner cylinder (23) and the outer cylinder (22) are coaxially arranged.

3. The system according to claim 1, characterized in that, The inner cavity of the outer cylinder (22) includes, from top to bottom, a connected aerobic granular sludge anoxic-anaerobic reaction zone (9) and sludge guiding zone (2), and the aerobic granular sludge anoxic-anaerobic reaction zone (9) is connected to the aerobic granular sludge aerobic reaction zone (4).

4. The system according to claim 3, characterized in that, The volume ratio of the aerobic reaction zone (4) of aerobic granular sludge to the anoxic-anaerobic reaction zone (9) of aerobic granular sludge is 1:2 to 1:

3.

5. The system according to claim 1, characterized in that, It also includes a sludge discharge assembly, which is connected to the sludge storage area (15).

6. The system according to claim 1, characterized in that, The aeration assembly includes an air source (13), an aeration check valve (11), an aeration throttle valve (12), and a microporous aeration disc assembly (14) connected in sequence; wherein the microporous aeration disc assembly (14) is located in the aeration zone.

7. The system according to claim 1, characterized in that, The inner cavity of the inner cylinder (23) is provided with an inner cylinder support column (19).

8. A wastewater treatment method, characterized in that, Wastewater is fed into the self-cultivation system of aerobic granular sludge in continuous flow as described in any one of claims 1 to 7.

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