Sludge circulating membrane biological sewage treatment device and method

Abstract

The invention discloses a sludge circulating membrane biological sewage treatment device and method. Comprising a cylindrical shell, and four annular galleries are coaxially arranged in the cylindrical shell; a treatment tank is arranged in the middle of the fourth annular gallery in the center; an anaerobic zone and an anoxic zone are arranged in the first annular gallery positioned on the outer side; the first aerobic zone is positioned in the second annular gallery; the second aerobic zone is positioned in the third annular gallery; the third aerobic zone is positioned in the fourth annular gallery; the MBR pre-anoxic zone is arranged in the treatment tank; the first annular gallery and the second annular gallery at the tail end of the anoxic zone are communicated through a through-wall pipe; the second annular gallery, the third annular gallery and the fourth annular gallery are communicated through wall penetrating pipes. The MBR pre-anoxic zone is arranged to replace a traditional secondary sedimentation tank, dissolved oxygen and nitrate nitrogen in returned sludge are partially consumed in the MBR pre-anoxic zone, the influence on anaerobic microorganisms in the anaerobic zone is reduced, and meanwhile, the occupied area of sewage treatment equipment can be saved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, specifically to a sludge recycling membrane biological wastewater treatment device and method. Background Technology

[0002] The AAO (Anaerobic-Anoxic-Oxic) process is one of the mainstream technologies in municipal wastewater treatment plants. It organically combines biological nitrogen and phosphorus removal processes in a single process, achieving high removal efficiency for both TN and TP. However, using the traditional AAO process for nitrogen and phosphorus removal still presents some unresolved issues: ① Sludge recirculation returns sludge-water rich in nitrate nitrogen and dissolved oxygen to the anaerobic zone. The presence of nitrate nitrogen and dissolved oxygen in the anaerobic zone inhibits the activity of phosphorus-releasing bacteria, severely reducing biological phosphorus removal efficiency; ② Drastic fluctuations in the influent COD, N, and P loads or ratios can affect the activity and balance of microorganisms in each functional zone, potentially leading to decreased treatment efficiency and substandard effluent quality; ③ Traditional AAO processes require a secondary sedimentation tank for sludge-water separation, resulting in a large construction footprint. Summary of the Invention

[0003] To overcome the above-mentioned defects, the present invention aims to provide a sludge recycling membrane biological wastewater treatment device and method.

[0004] To achieve the above objectives, the sludge circulating membrane biological wastewater treatment device of the present invention includes an anaerobic zone, an anoxic zone, an aerobic zone and an MBR pre-anoxic zone arranged sequentially; the device includes a cylindrical shell, and four annular corridors are coaxially arranged inside the cylindrical shell; a treatment tank is arranged in the middle of the fourth annular corridor located at the center. The first circular corridor on the outer side is equipped with anaerobic and hypoxic zones. The aerobic zone is divided into three sections: the first aerobic zone, the second aerobic zone, and the third aerobic zone. The first aerobic zone is located within the second annular corridor; the second aerobic zone is located within the third annular corridor; the third aerobic zone is located within the fourth annular corridor; the MBR pre-anoxic zone is located within the treatment tank. A through-wall pipe is installed between the first and second annular corridors at the end of the oxygen-deficient zone. The second, third, and fourth circular corridors are connected by through-wall pipes.

[0005] Furthermore, the MBR pre-hypoxia zone is divided into upper and lower sections; The upper section of the MBR pre-anoxic zone is the MBR filtration zone, which is cylindrical and contains a cylindrical membrane biofilter. The cylindrical membrane biofilter is driven to rotate by a variable frequency motor to reduce the risk of MBR membrane fouling. The effluent pipe of the MBR filtration zone is located in the center of the cylindrical membrane biofilter. The lower section of the MBR pre-anoxic zone is the sludge thickening zone. The air-lift device at the end of the second aerobic zone transports the sludge mixture to the sludge thickening zone in the lower section of the MBR pre-anoxic zone. In the sludge thickening zone, the sludge mixture achieves sludge-water separation, the sludge is continuously thickened, some of the thickened sludge is returned to the inlet end to mix with the inlet water, and the remaining sludge is discharged in a timely manner.

[0006] Furthermore, the anaerobic zone accounts for approximately 1 / 10 of the total reaction volume; the anoxic zone accounts for approximately 1 / 5 of the total reaction volume.

[0007] Furthermore, an adjustable actuator is installed in each annular corridor to drive the sewage to rotate clockwise along the annular corridor.

[0008] Furthermore, no aeration devices are installed at the bottom of the anaerobic and anoxic zones, but aeration devices are installed at the bottom of the aerobic zone. By controlling the number of aeration devices in operation, an anoxic zone is created in the aerobic zone. By adjusting the volume of the anoxic and aerobic zones, fluctuations in the quality and quantity of the incoming water can be addressed.

[0009] Furthermore, a flow booster is installed in the anoxic and / or anaerobic zone. By adjusting the operating frequency of the flow booster, the internal reflux ratio can be adjusted to achieve higher nitrogen removal efficiency.

[0010] To achieve the above objectives, the sludge recycling membrane biological wastewater treatment method of the present invention, which is based on the above-mentioned sludge recycling membrane biological wastewater treatment device, includes the following steps: 1) Wastewater enters the outer corridor and mixes with the sludge returned from the lower section of the MBR pre-anoxic zone before entering the anaerobic zone. The volume of the anaerobic zone accounts for about 1 / 10 of the total reaction volume. 2) Wastewater enters the anoxic zone and mixes with the nitrified liquid returned from the MBR pre-anoxic tank. The volume of the anoxic zone accounts for about 1 / 5 of the total reaction volume. 3) Wastewater flows by gravity into the inner corridor through the wall-penetrating pipe. The volume ratio of the anoxic zone to the aerobic zone in the inner corridor is controlled by the number of aeration devices activated at the bottom of the corridor. 4) Wastewater flows by gravity through the wall-penetrating pipe into the MBR pre-anoxic zone. The MBR pre-anoxic zone is divided into upper and lower sections. The upper section is the MBR filtration zone, which is cylindrical and rotated by a variable frequency motor to reduce the risk of MBR membrane fouling. The effluent pipe is located in the center of the cylindrical sludge circulation membrane biological filter. The lower section is the sludge thickening zone. The sludge-water mixture flows by gravity from the end of the third aerobic zone to the upper section of the MBR pre-anoxic zone and finally enters the sludge thickening zone. In the sludge thickening zone, the sludge-water mixture achieves sludge-water separation, and the sludge is continuously thickened. Part of the thickened sludge is returned to the influent end to mix with the influent, and the remaining sludge is discharged in a timely manner.

[0011] This invention replaces the traditional secondary sedimentation tank with a pre-anoxic zone in the MBR. Dissolved oxygen and nitrate nitrogen in the returned sludge are partially consumed in the pre-anoxic zone, reducing the impact on anaerobic microorganisms in the anaerobic zone, while also saving the floor space required for wastewater treatment equipment. Attached Figure Description

[0012] Figure 1 This is a plan view of a sludge recycling membrane biological wastewater treatment device.

[0013] Figure 2 This is a cross-sectional view of the pre-anoxic zone of the MBR.

[0014] Figure number explanation: 1: Anaerobic zone; 2: Anoxic zone; 3: First aerobic zone; 4: Second aerobic zone; 5: Third aerobic zone; 6: Through-wall pipe; 7: MBR pre-anoxic zone; 7.1: MBR filtration zone; 7.2: Sludge thickening zone; 8: Aeration device; 9: Flow promoter. Detailed Implementation

[0015] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0016] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0017] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0018] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] The sludge circulating membrane biological wastewater treatment device of this invention adopts a prefabricated modular assembly structure. The overall equipment is cylindrical and mainly includes an anaerobic zone 1, an anoxic zone 2, an aerobic zone, and an MBR pre-anoxic zone 7. The anaerobic and anoxic zones share a corridor, and the circulation of activated sludge is driven by a flow promoter. The aerobic zone is divided into a first aerobic zone 3, a second aerobic zone 4, and a third aerobic zone 5. The MBR pre-anoxic zone is located in the center. The sludge-water mixture flows by gravity into the upper section of the MBR pre-anoxic zone, while the sludge flows by gravity into the lower section of the MBR pre-anoxic zone as return sludge. The dissolved oxygen and nitrate nitrogen in the return sludge are partially consumed in the MBR pre-anoxic zone, reducing the impact on the anaerobic microorganisms in the anaerobic zone.

[0020] The first and second annular corridors at the end of the hypoxic zone are connected by a through-wall pipe 6; the second, third and fourth annular corridors are also connected by a through-wall pipe 6.

[0021] Wastewater flows by gravity into the inner corridor through the wall-penetrating pipe 6. The volume ratio of the anoxic zone to the aerobic zone is controlled by the number of aeration devices activated at the bottom of the corridor. An adjustable flow actuator is installed in each annular channel to drive the sewage to rotate clockwise along the annular channel.

[0022] Wastewater flows by gravity into the MBR pre-anoxic zone through the wall-penetrating pipe. The MBR pre-anoxic zone is divided into upper and lower sections. The upper section 7.1 is the MBR filtration zone. The MBR filtration zone is cylindrical and rotated by a variable frequency motor, which can reduce the risk of MBR membrane fouling. The effluent pipe is located in the center of the cylindrical sludge circulation membrane biological filter. The next section is the sludge thickening zone 7.2, where sludge-water separation is achieved in the sludge mixture. The sludge is continuously thickened, with some sludge returned to the influent end and the remaining sludge discharged promptly. This invention replaces the traditional secondary sedimentation tank with an MBR pre-anoxic zone. Dissolved oxygen and nitrate nitrogen in the returned sludge are partially consumed in the MBR pre-anoxic zone, reducing the impact on anaerobic microorganisms in the anaerobic zone and saving space occupied by wastewater treatment equipment.

[0023] No aeration devices are installed at the bottom of the anaerobic and anoxic zones, while aeration devices are installed at the bottom of the aerobic zones. The volume of the anoxic and aerobic zones can be adjusted by controlling the number of aeration devices in operation, thereby coping with fluctuations in the quality and quantity of incoming water. In addition, the circulation rate of sewage in the corridor can be adjusted by adjusting the operating frequency of the flow booster, thereby achieving higher pollutant removal efficiency.

[0024] Example 2 The wastewater treatment method of the present invention includes the following steps: 1) Wastewater enters the outer corridor and mixes with the sludge returned from the lower section of the MBR pre-anoxic zone before entering the anaerobic zone. The volume of the anaerobic zone accounts for about 1 / 10 of the total reaction volume. 2) Wastewater enters the anoxic zone and mixes with the nitrified liquid returned from the MBR pre-anoxic tank. The volume of the anoxic zone accounts for about 1 / 5 of the total reaction volume. 3) Wastewater flows by gravity into the inner corridor through the wall-penetrating pipe. The volume ratio of the anoxic zone to the aerobic zone in the inner corridor is controlled by the number of aeration devices activated at the bottom of the corridor. 4) Wastewater flows by gravity through the wall-penetrating pipe into the MBR pre-anoxic zone. The MBR pre-anoxic zone is divided into upper and lower sections. The upper section is the MBR filtration zone, which is cylindrical and rotated by a variable frequency motor to reduce the risk of MBR membrane fouling. The effluent pipe is located in the center of the cylindrical sludge circulation membrane biological filter. The lower section is the sludge thickening zone. The sludge-water mixture flows by gravity from the end of the third aerobic zone to the upper section of the MBR pre-anoxic zone and finally enters the sludge thickening zone. In the sludge thickening zone, the sludge-water mixture achieves sludge-water separation, and the sludge is continuously thickened. Part of the thickened sludge is returned to the influent end to mix with the influent, and the remaining sludge is discharged in a timely manner.

[0025] In summary, the present invention has the following characteristics: 1. The anaerobic zone and the anoxic zone share a corridor, and the circulation of activated sludge is driven by a flow booster.

[0026] 2. No aeration devices are installed at the bottom of the anaerobic and anoxic zones, but aeration devices are installed at the bottom of the aerobic tank. The volume of the anoxic and aerobic zones can be adjusted by controlling the number of aeration devices in operation, thereby coping with fluctuations in the quality and quantity of incoming water. In addition, the circulation rate of sewage in the corridor can be adjusted by adjusting the working frequency of the flow booster, thereby achieving higher pollutant removal efficiency.

[0027] 3. The MBR pre-anoxic zone is located in the center. The sludge-water mixture flows into the upper section of the MBR pre-anoxic zone by gravity, while the sludge flows into the lower section of the MBR pre-anoxic zone by gravity and becomes return sludge. The dissolved oxygen and nitrate nitrogen in the return sludge are partially consumed in the MBR pre-anoxic zone, reducing the impact on anaerobic microorganisms in the anaerobic zone.

[0028] The present invention has been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described above. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Many other changes and modifications made without departing from the concept and scope of the present invention should be considered within the scope of protection of the present invention.

[0029] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0030] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A sludge recycling membrane biological wastewater treatment device, comprising an anaerobic zone, an anoxic zone, an aerobic zone, and an MBR pre-anoxic zone arranged sequentially; characterized in that: The device includes a cylindrical shell, inside which four annular channels are coaxially arranged; a treatment pool is arranged in the middle of the fourth annular channel located at the center. The first circular corridor on the outer side is equipped with anaerobic and hypoxic zones. The aerobic zone is divided into three sections: the first aerobic zone, the second aerobic zone, and the third aerobic zone. The first aerobic zone is located within the second annular corridor; the second aerobic zone is located within the third annular corridor; the third aerobic zone is located within the fourth annular corridor; the MBR pre-anoxic zone is located within the treatment tank. A through-wall pipe is installed between the first and second annular corridors at the end of the oxygen-deficient zone. The second, third, and fourth circular corridors are connected by through-wall pipes.

2. The sludge recycling membrane biological wastewater treatment device as described in claim 1, characterized in that: The pre-hypoxia zone of the MBR is divided into upper and lower sections; The upper section of the MBR pre-anoxic zone is the MBR filtration zone, which is cylindrical and contains a cylindrical membrane biofilter. The cylindrical membrane biofilter is driven to rotate by a variable frequency motor to reduce the risk of MBR membrane fouling. The effluent pipe of the MBR filtration zone is located in the center of the cylindrical membrane biofilter. The lower section of the MBR pre-anoxic zone is the sludge thickening zone. The air-lift device at the end of the second aerobic zone transports the sludge mixture to the sludge thickening zone in the lower section of the MBR pre-anoxic zone. In the sludge thickening zone, the sludge mixture achieves sludge-water separation, the sludge is continuously thickened, some of the thickened sludge is returned to the inlet end to mix with the inlet water, and the remaining sludge is discharged in a timely manner.

3. The sludge recycling membrane biological wastewater treatment device as described in claim 1, characterized in that: The anaerobic zone accounts for about 1 / 10 of the total reaction volume; the anoxic zone accounts for about 1 / 5 of the total reaction volume.

4. The sludge recycling membrane biological wastewater treatment device as described in claim 1, characterized in that: An adjustable flow actuator is installed in each annular channel to drive the sewage to rotate clockwise along the annular channel.

5. The sludge recycling membrane biological wastewater treatment device as described in claim 1, characterized in that: No aeration devices are installed at the bottom of the anaerobic and anoxic zones, but aeration devices are installed at the bottom of the aerobic zone. By controlling the number of aeration devices in operation, an anoxic zone is created within the aerobic zone. By adjusting the volume of the anoxic and aerobic zones, fluctuations in the quality and quantity of the incoming water can be addressed.

6. The sludge recycling membrane biological wastewater treatment device as described in claim 1, characterized in that: A flow promoter is installed in the anoxic and / or anaerobic zone. By adjusting the operating frequency of the flow promoter, the internal reflux ratio can be adjusted to achieve higher nitrogen removal efficiency.

7. A sludge recycling membrane biological wastewater treatment method, wherein the method is implemented based on the sludge recycling membrane biological wastewater treatment device according to claim 1, characterized in that: Includes the following steps: 1) Wastewater enters the outer corridor and mixes with the sludge returned from the lower section of the MBR pre-anoxic zone before entering the anaerobic zone. The volume of the anaerobic zone accounts for about 1 / 10 of the total reaction volume. 2) Wastewater enters the anoxic zone and mixes with the nitrified liquid returned from the MBR pre-anoxic tank. The volume of the anoxic zone accounts for about 1 / 5 of the total reaction volume. 3) Wastewater flows by gravity into the inner corridor through the wall-penetrating pipe. The volume ratio of the anoxic zone to the aerobic zone in the inner corridor is controlled by the number of aeration devices activated at the bottom of the corridor. 4) Wastewater flows by gravity through the wall-penetrating pipe into the MBR pre-anoxic zone. The MBR pre-anoxic zone is divided into upper and lower sections. The upper section is the MBR filtration zone, which is cylindrical and rotated by a variable frequency motor to reduce the risk of MBR membrane fouling. The effluent pipe is located in the center of the cylindrical sludge circulation membrane biological filter. The lower section is the sludge thickening zone. The sludge-water mixture flows by gravity from the end of the third aerobic zone to the upper section of the MBR pre-anoxic zone and finally enters the sludge thickening zone. In the sludge thickening zone, the sludge-water mixture achieves sludge-water separation, and the sludge is continuously thickened. Part of the thickened sludge is returned to the influent end to mix with the influent, and the remaining sludge is discharged in a timely manner.

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