Double-sludge circulating membrane biological sewage treatment device and method

Abstract

The invention discloses a double-sludge circulating membrane biological sewage treatment device and a double-sludge circulating membrane biological sewage treatment method. Comprising a cylindrical shell, and four annular galleries are coaxially arranged in the cylindrical shell; an anaerobic zone and an anoxic zone are arranged in the first annular gallery; the first aerobic zone is positioned in the second annular gallery; the second aerobic zone is positioned in the third annular gallery; the aerobic nitrification area 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 and the third annular gallery at the tail end of the first aerobic zone are communicated through a through-wall pipe; and the fourth annular gallery and the third annular gallery at the tail end of the aerobic nitrification area are communicated through a through-wall pipe. According to the invention, the carbonized dephosphorized sludge is separated from the nitrified sludge, so that the sludge age contradiction of carbonized microorganisms, phosphorus-accumulating bacteria and nitrifying bacteria is solved; 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 dual sludge circulation 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 within a single process, achieving high removal efficiency for both total nitrogen (TN) and total phosphorus (TP). However, using the traditional AAO process for nitrogen and phosphorus removal still presents some unresolved issues: ① There is a conflict between sludge age and polyphosphate-accumulating bacteria (PABs) and nitrifying bacteria. Nitrifying bacteria require a longer sludge age (usually 10-15 days or more, and even longer at low temperatures) to ensure the stable existence of the slow-growing PABs and complete nitrification; polyphosphate-accumulating bacteria (PABs)... ① Os prefer a shorter sludge age (usually 3-7 days) to facilitate the timely discharge of phosphorus-rich excess sludge from the system and avoid secondary release of phosphorus from the sludge; ② Sludge recirculation will return 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 will inhibit the activity of phosphorus-releasing bacteria and severely reduce the efficiency of biological phosphorus removal; ③ Drastic fluctuations in the influent COD, N, and P load or ratio will affect the activity and balance of microorganisms in each functional zone, which may lead to a decrease in treatment efficiency and result in substandard effluent quality; ④ Traditional AAO processes require a secondary sedimentation tank for sludge-water separation, resulting in a large construction area. Summary of the Invention

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

[0004] To achieve the above objectives, the dual 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 aerobic nitrification zone. The first aerobic zone is located within the second annular corridor; the second aerobic zone is located within the third annular corridor; and the aerobic nitrification zone is located within the fourth annular corridor. The pre-anoxic zone of the MBR is set inside the treatment tank; A through-wall pipe is installed between the first and second annular corridors at the end of the oxygen-deficient zone. A through-wall pipe is installed between the second and third annular corridors at the end of the first aerobic zone; The fourth and third annular corridors at the end of the aerobic nitrification zone are connected by a through-wall pipe. An arc-shaped membrane bioreactor (MBR) and an air-lift device are installed at the end of the second aerobic zone. Wastewater is transported to the aerobic nitrification zone through the arc-shaped membrane bioreactor (MBR). Sludge is intercepted in the second aerobic zone. The aerobic nitrification zone is filled with packing material and adopts a biofilm process, allowing nitrifying bacteria with long generation cycles to multiply in large quantities.

[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 zone. By adjusting the operating frequency of the flow booster, the internal recirculation ratio can be adjusted to achieve higher nitrogen removal efficiency.

[0010] To achieve the above objectives, the present invention provides a dual-sludge circulating membrane biological wastewater treatment method, which is based on the aforementioned dual-sludge circulating membrane biological wastewater treatment device, and includes the following steps: 1) Wastewater enters from the anaerobic zone and mixes with sludge returned from the lower section of the MBR pre-anoxic 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) The sludge-water mixture flows into the aerobic zone by gravity and circulates continuously under the propulsion of the flow booster. The aerobic zone is divided into three sections: the first aerobic zone, the second aerobic zone, and the aerobic nitrification zone. An arc-shaped membrane bioreactor (MBR) and an air-lift device are installed at the end of the second aerobic zone. The wastewater is transported to the aerobic nitrification zone through the arc-shaped membrane bioreactor (MBR). The sludge is intercepted in the second aerobic zone. The aerobic nitrification zone is filled with packing material and adopts a biofilm process, allowing nitrifying bacteria with long generation cycles to multiply in large quantities. 4) Wastewater flows by gravity from the aerobic nitrification zone 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 membrane biological filter. The lower section is the sludge thickening zone. An 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, 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 separates carbonized phosphorus removal sludge from nitrification sludge, resolving the conflict between the sludge age of carbonizing microorganisms, polyphosphate-accumulating bacteria, and nitrifying bacteria. By setting up an MBR pre-anoxic zone to replace the traditional secondary sedimentation tank, dissolved oxygen and nitrate nitrogen in the returned sludge are partially consumed in the MBR pre-anoxic zone before being returned, reducing the impact on anaerobic microorganisms in the anaerobic zone and saving the floor space occupied by wastewater treatment equipment. Attached Figure Description

[0012] Figure 1 This is a plan view of the dual sludge circulation membrane biological wastewater treatment equipment.

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

[0014] Figure number explanations: 1: Anaerobic zone; 2: Anoxic zone; 3: First aerobic zone; 4: Second aerobic zone; 5: Aerobic nitrification zone; 6: Arc-shaped membrane bioreactor; 7: Air lift device; 8: MBR pre-anoxic zone; 8.1: MBR filtration zone; 8.2: Sludge thickening zone; 9: Nitrification packing; 10: Aeration device; 11: Through-wall pipe; 12: 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] Example 1 The dual-sludge circulating membrane biological wastewater treatment equipment 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 8. The anaerobic and anoxic zones share a corridor, while the aerobic zone has its own independent corridor. Wastewater enters the outer corridor, mixes with the returned sludge, and then enters the anaerobic zone. After mixing with the nitrifying liquid, it enters the anoxic zone. The wastewater enters the aerobic zone through the through-wall pipe 11 and eventually flows out from the pre-anoxic zone of the MBR. It is then continuously circulated between the anaerobic and aerobic zones by the submersible propeller 12.

[0020] The anaerobic and aerobic zones each have their own internal circulation ratios, which can be set according to the target removal rate of pollutants.

[0021] The aerobic zone is divided into three sections: the first aerobic zone 3, the second aerobic zone 4, and the aerobic nitrification zone 5. An arc-shaped membrane bioreactor (MBR) 6 and an air-lift device 7 are installed at the end of the second aerobic zone. Wastewater is transported to the aerobic nitrification zone via the arc-shaped membrane bioreactor (MBR). The aerobic nitrification zone is filled with packing material 9 and employs a pure biofilm process. The sludge mixture is transported to the pre-anoxic zone of the MBR via the air-lift device.

[0022] 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 membrane biofilter. The lower section is the sludge concentration zone, where sludge and liquid are separated. The sludge is continuously concentrated, with some sludge flowing back to the influent and the remaining sludge being discharged in a timely manner.

[0023] This invention separates carbonized phosphorus removal sludge from nitrification sludge, resolving the conflict between the sludge age of carbonizing microorganisms, polyphosphate-accumulating bacteria, and nitrifying bacteria. By setting up an MBR pre-anoxic zone to replace the traditional secondary sedimentation tank, dissolved oxygen and nitrate nitrogen in the returned sludge are partially consumed in the MBR pre-anoxic zone before being returned, reducing the impact on anaerobic microorganisms in the anaerobic zone and saving the floor space occupied by wastewater treatment equipment.

[0024] Example 2 The dual-sludge circulating membrane biological wastewater treatment method of the present invention is based on the above-mentioned dual-sludge circulating membrane biological wastewater treatment device and includes the following steps: 1) Wastewater enters from the anaerobic zone and mixes with sludge returned from the lower section of the MBR pre-anoxic 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) The sludge-water mixture flows into the aerobic zone by gravity and circulates continuously under the propulsion of the flow booster. The aerobic zone is divided into three sections: the first aerobic zone, the second aerobic zone, and the aerobic nitrification zone. An arc-shaped membrane bioreactor (MBR) and an air-lift device are installed at the end of the second aerobic zone. The wastewater is transported to the aerobic nitrification zone through the arc-shaped membrane bioreactor (MBR). The sludge is intercepted in the second aerobic zone. The aerobic nitrification zone is filled with packing material and adopts a biofilm process, allowing nitrifying bacteria with long generation cycles to multiply in large quantities. 4) Wastewater flows by gravity from the aerobic nitrification zone 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 membrane biological filter. The lower section is the sludge thickening zone. An 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, 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) No aeration devices are installed at the bottom of the anaerobic tank, but aeration devices are installed at the bottom of the aerobic tank. By controlling the number of aeration devices in operation, an anoxic zone can be created in the aerobic zone. By adjusting the volume of the anoxic zone and the aerobic zone, fluctuations in the quality and quantity of incoming water can be addressed. In addition, the internal recirculation ratio can be adjusted by adjusting the operating frequency of the flow booster, thereby achieving higher denitrification efficiency.

[0026] 2) The aerobic nitrification zone is a pure biofilm process with an independent sludge system. It only exchanges wastewater with the second aerobic zone and the MBR pre-anoxic zone, and there is no sludge exchange.

[0027] 3) The MBR pre-anoxic zone is located in the center. Wastewater from the aerobic nitrification zone enters the upper section of the MBR pre-anoxic zone through the weir, and sludge is lifted from the second aerobic zone into the lower section of the MBR pre-anoxic zone through the air lift pipe. 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.

[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 dual-sludge circulating 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 aerobic nitrification zone. The first aerobic zone is located within the second annular corridor; the second aerobic zone is located within the third annular corridor; and the aerobic nitrification zone is located within the fourth annular corridor. The pre-anoxic zone of the MBR is set inside the treatment tank; A through-wall pipe is installed between the first and second annular corridors at the end of the oxygen-deficient zone. A through-wall pipe is installed between the second and third annular corridors at the end of the first aerobic zone; The fourth and third annular corridors at the end of the aerobic nitrification zone are connected by a through-wall pipe. An arc-shaped membrane bioreactor and an air-lift device are installed at the end of the second aerobic zone. Wastewater is transported to the aerobic nitrification zone through the arc-shaped membrane bioreactor. Sludge is intercepted in the second aerobic zone. The aerobic nitrification zone is filled with packing material and adopts a biofilm process, allowing nitrifying bacteria with long generation cycles to multiply in large quantities.

2. The dual sludge circulation 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 dual sludge circulation 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 dual sludge circulation 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 dual sludge circulation 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 dual sludge circulation membrane biological wastewater treatment device as described in claim 1, characterized in that: An aerobic zone is equipped with a flow booster, and the internal recirculation ratio can be adjusted by adjusting the operating frequency of the flow booster.

7. A dual-sludge circulating membrane biological wastewater treatment method, wherein the method is based on a dual-sludge circulating membrane biological wastewater treatment device as described in claim 1, characterized in that: The method includes the following steps: 1) Wastewater enters from the anaerobic zone and mixes with sludge returned from the lower section of the MBR pre-anoxic 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) The sludge-water mixture flows into the aerobic zone by gravity and circulates continuously under the propulsion of the flow booster. The aerobic zone is divided into three sections: the first aerobic zone, the second aerobic zone, and the aerobic nitrification zone. An arc-shaped membrane bioreactor (MBR) and an air-lift device are installed at the end of the second aerobic zone. The wastewater is transported to the aerobic nitrification zone through the arc-shaped membrane bioreactor (MBR). The sludge is intercepted in the second aerobic zone. The aerobic nitrification zone is filled with packing material and adopts a biofilm process, allowing nitrifying bacteria with long generation cycles to multiply in large quantities. 4) Wastewater flows by gravity from the aerobic nitrification zone 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 membrane biological filter. The lower section is the sludge thickening zone. An 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, 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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