A sludge return sewage treatment system

Abstract

The application discloses a sludge backflow sewage treatment system, which comprises a water collecting well, a pre-anoxic tank, a first-stage anoxic tank, a first-stage aerobic tank, a second-stage anoxic tank, a second-stage aerobic tank and a secondary sedimentation tank which are sequentially connected, and a first fine adjustment weir which comprises a first water inlet groove, a first water distribution groove and a first overflow backflow groove. The first water inlet groove is used for receiving backflow sludge from the secondary sedimentation tank, and after the concentration of the first water inlet groove and the first water distribution groove is homogenized, the backflow sludge is together fed into the pre-anoxic tank, so that the pollutants in the treatment system are treated with stable sludge concentration, the concentration stratification is eliminated, the concentration of the mixed liquid entering the pre-anoxic tank is stabilized, and through the setting of the first overflow backflow groove, the water inlet exceeding the treatment capacity can be backflowed into the water collecting well, so that the mixed liquid backflow ratio in the first water distribution groove can be conveniently adjusted.

Description

Technical Field

[0001] This application relates to the field of wastewater technology, and in particular to a sludge return wastewater treatment system. Background Technology

[0002] In related technologies, in multi-stage AO wastewater treatment systems, in the pre-oxygenation tank, because the wastewater in the collection well directly enters the pre-anoxic tank, the sludge concentration in the biological treatment tank is difficult to control, affecting the overall wastewater treatment effect. Utility Model Content

[0003] This application provides a sludge return wastewater treatment system that can solve the technical problem that the sludge concentration in the biological treatment tank is difficult to control, thus affecting the overall wastewater treatment effect.

[0004] This application provides a sludge return wastewater treatment system, including a collection well, a pre-anoxic tank, a first-stage anoxic tank, a first-stage aerobic tank, a second-stage anoxic tank, a second-stage aerobic tank, and a secondary sedimentation tank arranged sequentially and interconnected. It also includes: The first fine-tuning weir includes a first inlet trough, a first distribution trough, and a first overflow return trough. The first overflow return trough is located inside the first inlet trough. The first inlet trough is connected to the first distribution trough and the collection well. The first inlet trough is connected to the secondary sedimentation tank through a first sludge return pipe. The first overflow return trough is connected to the collection well through a second sludge return pipe. The first distribution trough is connected to the pre-anoxic tank. In some embodiments, a mechanical bar is provided inside the water collection well. In some embodiments, an aeration device is provided at the bottom of both the first-stage aerobic tank and the second-stage aerobic tank, and the aeration device is connected to an aeration blower through an aeration pipe. In some embodiments, two aeration blowers are provided, and the two aeration blowers are connected in parallel. In some embodiments, the aeration pipe is also connected to an air lifting pipe, the other end of which is connected to the secondary sedimentation tank to transport a portion of the sludge from the secondary sedimentation tank to the first sludge return pipe. In some embodiments, a stirring tank and a coagulation sedimentation tank are arranged in sequence. The stirring tank is equipped with a dosing pipe and is connected to the secondary sedimentation tank and the coagulation sedimentation tank. In some embodiments, the coagulation sedimentation tank is equipped with baffles. In some embodiments, the secondary sedimentation tank has a first sewage discharge pipe, the coagulation sedimentation tank has a second sewage discharge pipe, both the first sewage discharge pipe and the second sewage discharge pipe are equipped with electric valves, and the first sewage discharge pipe and the second sewage discharge pipe are connected in parallel. In some embodiments, the first sludge return pipe is connected to the first sewage discharge pipe, and the connection node is located upstream of the electric valve in the first sewage discharge pipe. In some embodiments, a guide tube is provided in the secondary sedimentation tank, and the guide tube is connected to the two-stage aerobic tank through a pipe. The guide tube is located in the middle of the secondary sedimentation tank, and the outlet of the guide tube is funnel-shaped. The sludge return wastewater treatment system based on the embodiments of this application includes a collection well, a pre-anoxic tank, a first-stage anoxic tank, a first-stage aerobic tank, a second-stage anoxic tank, a second-stage aerobic tank, and a second sedimentation tank connected in sequence. A first fine-tuning weir includes a first inlet tank, a first distribution tank, and a first overflow return tank. The first inlet tank is used to receive the returned sludge from the second sedimentation tank. After the sludge is homogenized in the first inlet tank and the first distribution tank, it enters the pre-anoxic tank together to treat pollutants in the system with a stable sludge concentration, eliminate concentration stratification, and ensure that the concentration of the mixed liquor entering the pre-anoxic tank is stable. Secondly, by setting up the first overflow return tank, the excess water volume can be returned to the collection well, which makes it easier to adjust the mixed liquid return ratio in the first water distribution tank. Attached Figure Description

[0005] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0006] Figure 1 This is a schematic diagram of the sludge return wastewater treatment system provided in an embodiment of this application; Figure 2 A top view of the sludge return wastewater treatment system provided in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of the first fine-tuning weir provided in an embodiment of this application.

[0007] Figure reference numerals: 10. Water collection well; 11. Mechanical bar screen; 20. Pre-anoxic tank; 21. First fine-tuning weir; 211. First inlet channel; 212. First distribution channel; 212a. Distribution triangular weir plate; 213. First overflow return channel; 213a. Overflow return triangular weir plate; 30. An anoxic pool section; 40. Aerobic tank section; 41. Aeration device; 42. Aeration pipes; 43. Aeration blower; 50. Second-stage anoxic tank; 60. Second-stage aerobic tank; 70. Secondary sedimentation tank; 71. First sludge return pipeline; 72. Air lifting pipeline; 73. First sewage discharge pipeline; 74. Flow guide cylinder; 80. Mixing tank; 81. Chemical dosing pipeline; 90. Coagulation sedimentation tank; 91. Baffle plate; 92. Second sewage discharge pipe. Detailed Implementation

[0008] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0009] In existing technologies, in multi-stage AO wastewater treatment systems, the wastewater in the collection well directly enters the pre-anoxic tank, making it difficult to control the sludge concentration in the biological treatment tank and affecting the overall wastewater treatment effect.

[0010] To address the aforementioned technical problems, this application proposes a sludge return wastewater treatment system. Please refer to [link / reference]. Figure 1-2 The system includes a collection well 10, a pre-anoxic tank 20, a first-stage anoxic tank 30, a first-stage aerobic tank 40, a second-stage anoxic tank 50, a second-stage aerobic tank 60, and a second sedimentation tank 70, all connected in sequence. The entire multi-stage AO wastewater treatment system also includes a second fine-tuning weir.

[0011] The collection well 10 receives filtered wastewater, which then enters a pre-anoxic tank 20. In the pre-anoxic tank 20, anaerobic ammonia oxidation, a biological denitrification process, primarily occurs, where ammonia nitrogen and nitrite are converted into nitrogen gas under anaerobic conditions. The wastewater then enters a primary anoxic tank 30, which serves as the main denitrification section. It receives nitrified liquid from the secondary aerobic tank 60 and further denitrifies using the remaining organic matter. The wastewater then enters a primary aerobic tank 40, a high-load nitrification section where ammonia nitrogen is oxidized to nitrate, and heterotrophic bacteria decompose the remaining organic matter. The wastewater then enters the second-stage anoxic tank 50, which is a deep denitrification stage, also known as an enhanced denitrification stage. This stage utilizes the endogenous metabolic products of microorganisms to convert residual nitrates into nitrogen gas. Some denitrifying polyphosphate bacteria simultaneously remove nitrogen and phosphorus, saving carbon sources. The wastewater then enters the second-stage aerobic tank 60, which is a low-load protection stage. This stage oxidizes trace amounts of residual ammonia nitrogen to the greatest extent possible, preventing the effluent ammonia nitrogen from exceeding the standard. Polyphosphate bacteria absorb phosphorus again, enhancing the biological phosphorus removal effect. Under low load, the microorganisms enter the endogenous respiration period, reducing the production of excess sludge. The wastewater then enters the secondary sedimentation tank 70 for sedimentation.

[0012] It should be understood that the above content only provides a general description of the functions of each tank. Since the existing multi-stage AO wastewater treatment technology includes the above-mentioned tanks, their further functions will not be described in detail here.

[0013] Please see Figure 3 The first fine-tuning weir will now be explained in more detail.

[0014] The first fine-tuning weir 21 includes a first inlet channel 211, a first distribution channel 212, and a first overflow return channel 213. The first overflow return channel 213 is located inside the first inlet channel 211. The first inlet channel 211 is connected to the first distribution channel 212 and the collection well 10. The first inlet channel 211 is connected to the secondary sedimentation tank 70 through the first sludge return pipe 71. The first overflow return channel 213 is connected to the collection well 10 through the second sludge return pipe. The first distribution channel 212 is connected to the pre-anoxic tank 20. It can be understood that the connection between the collection well 10 and the pre-anoxic tank 20 is achieved through the first fine-tuning weir 21.

[0015] The first inlet tank 211 receives sludge from the secondary sedimentation tank 70 through the first sludge return pipe 71 and wastewater from the collection well 10. The wastewater then enters the pre-anoxic tank 20 through the first distribution tank 212. Excess water flows back to the collection well 10 through the first overflow return tank 213. This controls the inflow of water into the pre-anoxic tank 20 and stabilizes the pollutants in the sludge concentration treatment system.

[0016] In addition, the sludge and raw water are fully mixed in the weir to eliminate concentration stratification and ensure that the concentration of the mixed liquor entering the pre-anoxic tank 20 is stable. The fluctuation range of the mixed liquor sludge concentration is reduced from ±50% to ±10%, the treatment efficiency of the biological treatment tank is improved, and the high concentration of influent pollutants (such as COD peak) is diluted through the buffer in the weir, reducing the risk of system shock.

[0017] It is understood that the fine-tuning weir can be a triangular weir. The first inlet channel 211 and the first distribution channel 212 are separated by the distribution triangular weir plate 212a, and the first inlet channel 211 and the first distribution channel 212 are separated by the overflow return triangular weir plate 213a. However, the water in the first inlet channel 211 can enter the first distribution channel 212 through the overflow return triangular weir plate 213a, and the water in the first inlet channel 211 can also enter the first distribution channel 212 through the distribution triangular weir plate 212a. Optionally, the height of the distribution triangular weir plate 212a and the overflow return triangular weir plate 213a are both adjustable, and can be adjusted electrically or manually.

[0018] In practice, the water distribution triangular weir plate 212a is adjusted to the required flow rate scale, and the overflow return water triangular weir plate 213a is adjusted to the same elevation as this scale. At this time, the water exceeding the treatment capacity of the first inlet tank 211 can flow back to the water pool of the incoming water, i.e. the collection well 10, through the first overflow return tank 213, thereby achieving the purpose of accurately controlling the treatment capacity.

[0019] It is important to understand that, since the sludge returned from the secondary sedimentation tank 70 is homogenized with the influent through the first fine-tuning weir 21 and then enters the pre-anoxic tank 20, the sludge settled in the secondary sedimentation tank 70 can be reintroduced into the pre-anoxic tank 20 through sludge return, thereby replenishing the sludge load in this area, ensuring that the number and activity of microorganisms meet the treatment requirements, and sludge return also helps to maintain the sludge concentration of the entire wastewater treatment system.

[0020] In the pre-anoxic tank 20, the nitrified liquid (containing nitrate nitrogen) brought by the sludge return can be used as a substrate for denitrification, which can make full use of the anoxic conditions to promote denitrification and improve the denitrification efficiency of the system.

[0021] Furthermore, in the activated sludge process, polyphosphate-accumulating organisms (PAOs) remove phosphorus through anaerobic phosphorus release and aerobic phosphorus uptake metabolic activities. Returning sludge to the pre-anoxic tank 20 (typically in an anaerobic or facultative anaerobic state) facilitates anaerobic phosphorus release by PAOs, preparing them for subsequent aerobic phosphorus uptake.

[0022] Optionally, a mechanical screen 11 is installed inside the water collection well 10. The main function of the mechanical screen 11 in the water collection well 10 is to filter solid debris in the water, such as leaves, gravel, soil, fibers, hair, fruit peels, vegetables, wood chips, cloth strips, and plastic products. Through the interception of the mechanical screen 11, these solid debris can be effectively prevented from entering the water collection well 10, thereby avoiding blockage or damage to subsequent water treatment equipment.

[0023] The mechanical bar screen 11 includes a frame, transmission mechanism, power mechanism, cleaning accessories, and cleaning mechanism. The frame is the skeleton supporting the entire bar screen equipment, playing a role in supporting and fixing other components. It is usually made of carbon steel or stainless steel to ensure the stability and corrosion resistance of the equipment. The transmission mechanism is the power unit of the entire equipment, responsible for driving the operation of the bar screen. It is usually composed of connecting plates, sprockets, and other accessories, and achieves continuous or intermittent movement of the bar screen through the drive of a motor or reducer. The power mechanism is mainly a motor and reducer, providing the necessary power for the operation of the bar screen. The motor and reducer transmit power to the transmission mechanism through gear transmission or belt transmission, thereby driving the bar screen to work. The cleaning accessories are the core part of the bar screen, mainly responsible for intercepting and removing solid debris in sewage. Rake teeth are the main form of cleaning accessories, and their materials are usually divided into nylon rake teeth and stainless steel rake teeth. Driven by the transmission mechanism, the rake teeth reciprocate between the bar screen bars, intercepting and removing solid debris.

[0024] The cleaning system is used to remove debris adhering to the rake teeth during the operation of the screen. The cleaning system typically includes equipment such as rubber brushes and pressurized flushing water.

[0025] Optionally, both the first-stage aerobic tank 40 and the second-stage aerobic tank 60 are equipped with aeration devices 41 at their bottoms. The aeration devices 41 are connected to an aeration fan 43 via aeration pipes 42. The aeration devices 41 deliver air into the aerobic tanks through the aeration pipes 42, ensuring sufficient contact between the air and the water, thereby increasing the dissolved oxygen content in the water. Dissolved oxygen is essential for the metabolic activities of aerobic microorganisms and is crucial for the oxidation and decomposition of organic matter. Therefore, this design provides a sufficient oxygen supply for aerobic microorganisms, promoting their growth and metabolic activities.

[0026] In addition, under sufficient dissolved oxygen conditions, aerobic microorganisms can efficiently decompose and oxidize organic matter, converting it into inorganic matter, thereby reducing the concentration of organic matter in the water. This process not only helps reduce the pollution of water quality by organic matter, but also enhances the self-purification capacity of the water body.

[0027] Optionally, the bubbles released by the aeration device 41 form a bubble flow in the water, which can agitate the water and enhance the mixing effect. This mixing effect helps to fully mix microorganisms and dissolved oxygen in the water, improves the mass transfer efficiency of oxygen and organic matter, and thus enhances the removal effect of organic matter. Optionally, see Figure 1 There are two aeration blowers 43, which are connected in parallel. The two parallel aeration blowers 43 can provide a larger gas flow rate, thereby meeting the needs of larger-scale wastewater treatment. In the treatment of high-concentration organic wastewater or in the case of needing higher dissolved oxygen concentration, the parallel blowers can ensure sufficient oxygen supply.

[0028] The two aeration blowers 43 are set in parallel so that when one blower fails, the other blower can still work independently, ensuring the continuity of wastewater treatment. This redundancy design reduces the risk of system downtime due to the failure of a single device.

[0029] Please see Figure 1 In one embodiment of this application, the aeration pipe 42 is also connected to the air lifting pipe 72. The other end of the air lifting pipe 72 is connected to the secondary sedimentation tank 70 to transport part of the sludge in the secondary sedimentation tank 70 to the first sludge return pipe 71. When the gas (such as air) in the aeration pipe 42 enters the secondary sedimentation tank 70 through the air lifting pipe 72, a certain pressure difference will be formed in the pipe. This pressure difference will push the sludge in the secondary sedimentation tank 70 into the sludge return pipe and finally into the pre-anoxic tank 20.

[0030] Since there is no need to use a traditional sludge return pump, the aeration pipe 42, which directly supplies air to the first aerobic tank 40 and the second aerobic tank 60, reduces energy consumption and maintenance costs.

[0031] Optionally, it also includes a mixing tank 80 and a coagulation sedimentation tank 90 arranged in sequence. The mixing tank 80 is equipped with a dosing pipe 81, and the mixing tank 80 is connected to the secondary sedimentation tank 70 and the coagulation sedimentation tank 90.

[0032] Secondary sedimentation tank 70 is mainly used to remove suspended solids and organic matter from wastewater, further purifying the water quality. In secondary sedimentation tank 70, suspended solids in wastewater settle to the bottom under gravity, forming sludge, while the supernatant is discharged as treated water.

[0033] The supernatant discharged from the secondary sedimentation tank 70 enters the mixing tank 80, which is usually equipped with a stirrer. In addition, the mixing tank 80 is equipped with a chemical dosing pipe 81 for adding coagulants, flocculants and other chemicals into the tank. The stirrer ensures that the wastewater and chemicals are mixed evenly.

[0034] The coagulation sedimentation tank 90 is used to receive the mixed water from the mixing tank 80, and is used to further remove suspended solids and colloidal substances from the wastewater. In the coagulation sedimentation tank 90, the particulate matter in the wastewater forms larger flocs under the action of coagulants and flocculants, and then settles to the bottom under gravity. The resulting supernatant can be discharged and recycled.

[0035] Further, see Figure 1 The coagulation sedimentation tank 90 is equipped with a baffle plate 91. The baffle plate 91 changes the direction of water flow, causing the water flow to make multiple turns within the coagulation sedimentation tank 90, thereby extending the water flow path and the residence time of suspended solids. The extended water flow path provides more opportunities for suspended solids to settle, which helps to improve the settling efficiency.

[0036] The baffle 91 can be a "V" shaped baffle 91, or it can be other baffles 91 in the prior art, which will not be explained in detail here.

[0037] The secondary sedimentation tank 70 has a first sewage discharge pipe 73, and the coagulation sedimentation tank 90 has a second sewage discharge pipe 92. Both the first sewage discharge pipe 73 and the second sewage discharge pipe 92 are equipped with electric valves, and the first sewage discharge pipe 73 and the second sewage discharge pipe 92 are connected in parallel.

[0038] The first sewage discharge pipe 73 is used to discharge the sludge settled in the secondary sedimentation tank 70, and the second sewage discharge pipe 92 is used to discharge the sludge settled in the coagulation sedimentation tank 90. ​​The electric valve is used to control the opening and closing of the first sewage discharge pipe 73 and the second sewage discharge pipe 92, thereby regulating the discharge flow of sludge and water. Through the precise control of the electric valve, the periodic discharge of sludge and the flexible adjustment of the system can be realized.

[0039] Furthermore, by connecting the first sewage pipe 73 and the second sewage pipe 92 in parallel, the pipe layout is optimized, reducing unnecessary pipe length and the number of bends. This rational pipe layout allows for more efficient use of space, ensuring the system operates efficiently within a compact environment.

[0040] The discharge sequence of the first sewage pipe 73 and the second sewage pipe 92 can also be controlled by the electric valve. For example, when the first sewage pipe 73 discharges sludge, the second sewage pipe 92 can stop working and reduce the pipe pressure.

[0041] In one embodiment of this application, the first sludge return pipe 71 is connected to the first sewage discharge pipe 73, and the connection node is located upstream of the electric valve in the first sewage discharge pipe 73. That is, the first sludge return pipe 71 forms a branch pipe. Sludge can be discharged through the first sewage discharge pipe 73 or fed into the first sludge return pipe 71, thereby optimizing the pipe layout and reducing unnecessary pipe length and the number of bends. Through a reasonable pipe layout, space can be utilized more effectively, ensuring that the system operates efficiently in a compact space.

[0042] Optionally, please refer to Figure 1 A guide tube 74 is installed in the secondary sedimentation tank 70. The guide tube 74 is connected to the second aerobic tank 60 through a pipe. The guide tube 74 is located in the middle of the secondary sedimentation tank 70, and the outlet of the guide tube 74 is funnel-shaped.

[0043] The guide tube 74 can evenly introduce the mixed liquor in the second-stage anoxic tank 50 into the second sedimentation tank 70. Since the outlet of the guide tube 74 is funnel-shaped, it can reduce water flow impact and avoid short-circuiting or excessive local flow velocity, which would affect the sedimentation effect.

[0044] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "left," and "right" 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 application 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, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0045] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A sludge return wastewater treatment system, characterized in that, This includes a collection well, a pre-anoxic tank, a first-stage anoxic tank, a first-stage aerobic tank, a second-stage anoxic tank, a second-stage aerobic tank, and a secondary sedimentation tank, all connected in sequence. It also includes: The first fine-tuning weir includes a first inlet trough, a first distribution trough, and a first overflow return trough. The first overflow return trough is located inside the first inlet trough. The first inlet trough is connected to the first distribution trough and the collection well. The first inlet trough is connected to the secondary sedimentation tank through a first sludge return pipe. The first overflow return trough is connected to the collection well through a second sludge return pipe. The first distribution trough is connected to the pre-anoxic tank.

2. The sludge return wastewater treatment system according to claim 1, characterized in that, The water collection well is equipped with a mechanical screen.

3. The sludge return wastewater treatment system according to claim 1, characterized in that, Both the first-stage aerobic tank and the second-stage aerobic tank are equipped with aeration devices at the bottom, and the aeration devices are connected to the aeration blowers through aeration pipes.

4. The sludge return wastewater treatment system according to claim 3, characterized in that, There are two aeration blowers, which are connected in parallel.

5. The sludge return wastewater treatment system according to claim 3, characterized in that, The aeration pipe is also connected to an air lifting pipe, the other end of which is connected to the secondary sedimentation tank to transport part of the sludge from the secondary sedimentation tank to the first sludge return pipe.

6. The sludge return wastewater treatment system according to claim 1, characterized in that, It also includes a mixing tank and a coagulation sedimentation tank arranged in sequence. The mixing tank is equipped with a dosing pipe and is connected to the secondary sedimentation tank and the coagulation sedimentation tank.

7. The sludge return wastewater treatment system according to claim 6, characterized in that, The coagulation sedimentation tank is equipped with baffles.

8. The sludge return wastewater treatment system according to claim 6, characterized in that, The secondary sedimentation tank has a first sewage discharge pipe, and the coagulation sedimentation tank has a second sewage discharge pipe. Both the first sewage discharge pipe and the second sewage discharge pipe are equipped with electric valves, and the first sewage discharge pipe and the second sewage discharge pipe are connected in parallel.

9. The sludge return wastewater treatment system according to claim 8, characterized in that, The first sludge return pipe is connected to the first sewage discharge pipe, and the connection node is located upstream of the electric valve in the first sewage discharge pipe.

10. The sludge return wastewater treatment system according to claim 1, characterized in that, A flow guide tube is installed in the secondary sedimentation tank. The flow guide tube is connected to the two-stage aerobic tank through a pipe. The flow guide tube is located in the middle of the secondary sedimentation tank, and the outlet of the flow guide tube is funnel-shaped.

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