Multistage precipitation and dephosphorization integrated device for sewage treatment

Abstract

The utility model discloses a multistage precipitation and dephosphorization integrated device for sewage treatment, and belongs to the technical field of sewage treatment. The technical scheme adopted by the utility model is as follows: the multi-stage sedimentation and dephosphorization integrated device for sewage treatment comprises a pretreatment tank, an anaerobic treatment tank, an anoxic treatment tank and an aerobic treatment tank which are communicated in sequence, wherein a third guide pipe is connected between the anoxic treatment tank and the aerobic treatment tank, and the third guide pipe is connected to the middle lower part of the aerobic treatment tank from the middle upper part of the anoxic treatment tank; through the pretreatment tank, the anaerobic treatment tank, the anoxic treatment tank and the aerobic treatment tank which are sequentially communicated, and by combining the change of the cross section of the connecting pipe and the optimization of the position of the air inlet pipe, efficient aeration and gas-liquid mixing are realized, the use of chemical agents is reduced, the phosphorus recovery rate is improved, and meanwhile, the occupied area and the sludge treatment cost are reduced by the integrated structure; the device has the advantages that the treatment efficiency is improved, the energy consumption is reduced, the dependence on chemical agents is reduced, the aeration effect is optimized, and the integration degree is improved.

Description

Technical Field

[0001] This utility model belongs to the field of wastewater treatment technology, specifically relating to an integrated device for multi-stage sedimentation and phosphorus removal in wastewater treatment. Background Technology

[0002] With the acceleration of urbanization, the efficient removal of nitrogen and phosphorus in wastewater treatment has become crucial to curbing eutrophication. While traditional processes can achieve multi-stage treatment, they generally suffer from high energy consumption, poor process synergy, and strong dependence on chemical agents, severely hindering the green transformation of wastewater treatment technology. Traditional processes employ separate anaerobic, anoxic, and aerobic units, resulting in large equipment footprints and difficulties in controlling hydraulic retention time and sludge return between units. Furthermore, the aerobic stage relies on energy-intensive aeration equipment; traditional aeration systems have low oxygen utilization rates and are prone to dead zones due to uneven aeration, further reducing treatment efficiency. Traditional chemical precipitation methods require the addition of iron and aluminum salts, which, while simple to operate, involve large dosages, increased sludge production, and the risk of heavy metal residues, contradicting the concept of sustainable development. Sludge generated from multi-stage sedimentation requires multiple transfers and separate treatments, resulting in low integration. Existing processes have insufficient phosphorus recovery rates from sludge, leading to phosphorus resource waste. Traditional gas-liquid mixing devices such as Venturi tubes are prone to clogging in wastewater with high suspended solids, resulting in high maintenance costs. In recent years, integrated devices have become a research hotspot, but there are still significant shortcomings.

[0003] To address the aforementioned issues, there is an urgent need to develop an integrated device that combines multi-stage sedimentation, high-efficiency phosphorus removal, and low-energy aeration. This device should achieve reduced energy consumption, enhanced process synergy, chemical reagent substitution, modularization, and intelligent operation through structural optimization. Existing technologies urgently require improvement to address these problems. Utility Model Content

[0004] This invention provides an integrated device for multi-stage sedimentation and phosphorus removal in wastewater treatment to solve at least one of the aforementioned technical problems.

[0005] The technical solution adopted in this utility model is as follows:

[0006] An integrated multi-stage sedimentation and phosphorus removal device for wastewater treatment includes a pretreatment tank, an anaerobic treatment tank, an anoxic treatment tank, and an aerobic treatment tank connected in sequence. A third conduit connects the anoxic treatment tank and the aerobic treatment tank, extending from the upper part of the anoxic treatment tank to the lower part of the aerobic treatment tank. A connecting pipe is provided on the third conduit, with the cross-sectional area decreasing and then increasing along the direction of medium flow. An air inlet pipe is provided on the side wall of the connecting pipe, located at the minimum cross-sectional area of ​​the connecting pipe.

[0007] Furthermore, this application also proposes that an air guide pipe is connected between the aerobic treatment tank and the anoxic treatment tank, with the air guide pipe extending from the upper end of the aerobic treatment tank to the lower middle part of the anoxic treatment tank.

[0008] Furthermore, this application also proposes that the connecting pipe includes a pipe wall, the cross-section of the channel inside the pipe wall first decreases and then increases along the medium flow direction, a guide cone is provided inside the connecting pipe, a medium channel is provided between the guide cone and the inner wall of the connecting pipe, a gas nozzle is provided on the guide cone, the gas nozzle extends along the medium flow direction, a spiral gas guiding channel is provided on the outer side of the pipe wall, and the air inlet pipe is connected to the gas nozzle through the spiral gas guiding channel.

[0009] Furthermore, this application also proposes that the aerobic treatment tank is equipped with a stirring mechanism, which includes a drive motor, a stirring shaft is rotatably connected inside the aerobic treatment tank, a stirring rod is provided at the bottom of the stirring shaft, the output end of the drive motor is fixedly connected to the stirring shaft, and a drain pipe is provided at the bottom of the aerobic treatment tank.

[0010] Furthermore, this application also proposes that the pretreatment tank is a sedimentation tank, the bottom of the pretreatment tank is provided with a sludge discharge pipe, and a first conduit is connected between the pretreatment tank and the anaerobic treatment tank, with a pump installed on the first conduit.

[0011] Furthermore, this application also proposes that a second conduit connects the anaerobic treatment tank and the anoxic treatment tank, with the two ends of the second conduit connected to the upper middle part of the anaerobic treatment tank and the lower middle part of the anoxic treatment tank, respectively.

[0012] Furthermore, this application also proposes that valves are provided on the first conduit, the second conduit, and the third conduit.

[0013] Furthermore, this application also proposes that a filter element is detachably connected to the outer end of the intake pipe.

[0014] As can be seen from the above, the wastewater treatment multi-stage sedimentation and phosphorus removal integrated device provided in this application achieves efficient aeration and gas-liquid mixing by sequentially connecting a pretreatment tank, an anaerobic treatment tank, an anoxic treatment tank, and an aerobic treatment tank, combined with the cross-sectional changes of the connecting pipes and the optimized position of the air inlet pipe. This reduces the use of chemical agents and improves the phosphorus recovery rate. At the same time, the integrated structure reduces the footprint and sludge treatment cost. It has the advantages of improving treatment efficiency, reducing energy consumption, reducing dependence on chemical agents, optimizing aeration effect, and improving the degree of integration.

[0015] Due to the adoption of the above technical solution, the beneficial effects achieved by this utility model are as follows:

[0016] 1. In this application, during the process of the medium entering the aerobic treatment tank through the third conduit, the cross-section of the connecting pipe contracts, increasing the flow velocity. Gas is drawn in through the inlet pipe at the minimum cross-section, while the flow velocity decreases in the expansion section, forming a vortex and prolonging the gas-liquid contact time. This structure utilizes fluid kinetic energy to achieve self-priming aeration, avoiding the high energy consumption problem of traditional mechanical aeration. After the nitrification reaction is completed in the aerobic treatment tank, the mixed liquid is returned to the anoxic treatment tank through the gas guide pipe to form an internal circulation.

[0017] The gas-liquid mixing process is integrated into the connecting pipe, ensuring that dissolved oxygen reaches saturation during the media transport stage. Existing technologies often place the gas injection point in the converging section in the Chinese-made Tu-tube system. This design places the inlet pipe at the minimum cross-section, utilizing the negative pressure generated by the maximum flow velocity to enhance gas intake.

[0018] Through the above technical solution, this application achieves simultaneous gas-liquid mixing and wastewater transportation, reducing the construction cost of the aeration system. The variable diameter connecting pipe structure effectively prevents pipe blockage caused by suspended solids accumulation, reducing equipment maintenance frequency. The self-priming gas injection method eliminates the need for an external air compressor, saving energy consumption while achieving the same oxygen transfer efficiency. Dissolved oxygen is evenly distributed during the transportation stage, avoiding localized anoxic areas within the aerobic treatment tank and improving the stability of the nitrification reaction.

[0019] 2. This solution achieves internal gas circulation between the aerobic treatment tank and the anoxic treatment tank through a gas delivery pipe, directly utilizing the gas with a lower oxygen concentration generated in the aerobic section as the gas source for the anoxic section, without the need for additional aeration equipment.

[0020] Through the above technical solution, this application effectively reduces the aeration energy consumption of the anoxic treatment section, while avoiding the risk of pipeline blockage caused by independent aeration equipment. The rising process of gas in the anoxic treatment tank enhances the mixing effect of sludge and wastewater, promotes the reduction reaction of nitrate by denitrifying bacteria, and improves denitrification efficiency.

[0021] 3. This solution forms an independent gas delivery path through a spiral gas guide channel, preventing impurities from entering the gas path system. At the same time, the annular flow channel formed by the guide cone and the pipe wall keeps the medium flowing smoothly, achieving efficient gas-liquid mixing while reducing the risk of blockage.

[0022] This application effectively solves the technical problem of easy clogging of gas-liquid mixing devices in the treatment of wastewater with high suspended solids. It significantly extends the equipment maintenance cycle while maintaining oxygen mass transfer efficiency. At the same time, through the synergistic effect of the spiral air guide path and the guide cone, the uniformity of bubble distribution is improved and the aeration energy consumption is reduced.

[0023] 4. This solution uses mechanical stirring instead of traditional aeration mixing. An adjustable-speed stirring mechanism achieves liquid circulation throughout the entire tank, avoiding complex piping layouts in the aeration system and reducing power consumption per unit throughput. Compared to fixed aeration devices, the dynamic flow field created by the rotating stirring rod more effectively prevents activated sludge sedimentation.

[0024] Through the above technical solution, this application achieves uniform distribution of dissolved oxygen during aerobic treatment, ensuring sufficient contact between nitrifying bacteria and organic matter. Simultaneously, the shear force generated by mechanical stirring promotes biofilm renewal. The bottom drain pipe remains unobstructed under continuous stirring, effectively solving the pipe blockage problem caused by sludge deposition during traditional static drainage and reducing equipment maintenance frequency.

[0025] 5. This solution achieves directional flow of the medium without external power by connecting the second conduit at a staggered height. At the same time, it optimizes carbon source transfer efficiency by utilizing spatial position differences, reducing the fluctuation of denitrification and phosphorus removal efficiency caused by carbon source competition.

[0026] Through the above technical solution, this application achieves precise matching of the carbon source between the phosphorus release products of the anaerobic stage and the denitrification requirements of the anoxic stage, effectively suppressing the competitive consumption of organic matter by denitrifying bacteria and polyphosphate-accumulating bacteria, and solving the problem of reduced treatment efficiency caused by the imbalance of carbon source distribution in traditional processes. At the same time, the countercurrent movement of the medium in the anoxic treatment tank enhances the contact between sludge and liquid phase, reduces the risk of short-circuiting, and improves denitrification stability. Attached Figure Description

[0027] Figure 1 This is a structural schematic diagram of a specific embodiment of the present utility model;

[0028] Figure 2 This is a schematic diagram of the connecting pipe in this utility model;

[0029] Figure 3 This is a schematic diagram of the internal structure of the connecting pipe in this utility model.

[0030] The accompanying drawings, which are provided to further illustrate the present invention and constitute a part of the present invention, illustrate exemplary embodiments of the present invention and are used to explain the present invention, but do not constitute an undue limitation of the present invention.

[0031] In the attached diagram:

[0032] 1. Pretreatment tank; 11. First conduit; 12. Sludge discharge pipe; 2. Anaerobic treatment tank; 21. Second conduit; 3. Anoxic treatment tank; 31. Third conduit; 4. Aerobic treatment tank; 41. Drive motor; 42. Stirring shaft; 43. Stirring rod; 44. Drain pipe; 5. Connecting pipe; 51. Guide cone; 52. Gas nozzle; 53. Spiral air guide channel; 54. Air inlet pipe; 6. Air guide pipe. Detailed Implementation

[0033] To more clearly illustrate the overall concept of this utility model, a detailed description will be provided below with reference to the accompanying drawings.

[0034] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0035] Furthermore, it should be understood in the description of this utility model that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", 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 utility model 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 utility model.

[0036] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0037] In this invention, unless otherwise expressly specified and limited, the first feature "on" or "below" the second feature may be in direct contact with the first and second features, or indirect contact through an intermediate medium. In the description of this specification, references to terms such as "implementation," "example," "aspect," or "specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0038] Those skilled in the art will understand that wastewater treatment processes generally suffer from problems such as dispersed unit layouts, high energy consumption, and strong dependence on chemical agents. Traditional multi-stage treatment systems employ a split structure, resulting in large equipment footprints and difficulties in controlling sludge return. High-energy-consuming aeration equipment has low oxygen utilization rates, and chemical precipitation methods generate large amounts of sludge containing heavy metals. At a certain wastewater treatment plant, during peak nighttime treatment times, uneven aeration caused fluctuations in dissolved oxygen concentration, leading to competition for carbon sources between denitrifying bacteria and polyphosphate-accumulating bacteria, resulting in periodic exceedances of total phosphorus concentration in the effluent. Simultaneously, aeration pipes were frequently blocked due to the accumulation of suspended solids.

[0039] To address these issues, researchers noticed a direct correlation between aeration efficiency and pipe structure. Traditional Venturi tubes, with their fixed cross-section, are prone to sedimentation in environments with high suspended matter content. Fluid dynamics simulations revealed that the tapering region accelerates media flow, but excessive contraction exacerbates particle collisions. Therefore, a variable-diameter structure with a decreasing and then increasing cross-section was proposed to accelerate mixing while reducing pressure loss. Further experiments showed that introducing gas at the minimum cross-section creates vortices to enhance gas-liquid mass transfer; however, conventional lateral air intake is easily dispersed by high-speed water flow, necessitating optimization of the gas injection angle and position.

[0040] Reference Figures 1-3 This application proposes an apparatus comprising a pretreatment tank 1, an anaerobic treatment tank 2, an anoxic treatment tank 3, and an aerobic treatment tank 4 connected in sequence. A third conduit 31 is provided between the anoxic treatment tank 3 and the aerobic treatment tank 4, extending from the upper part of the anoxic treatment tank 3 to the lower part of the aerobic treatment tank 4. A connecting pipe 5 is installed on the third conduit 31, the cross-section of the medium channel of the connecting pipe 5 first decreasing and then increasing along the flow direction, and an air inlet pipe 54 connecting to the interior is provided at the point of minimum cross-section on the side wall.

[0041] The pretreatment tank 1 is a primary treatment unit for separating suspended solids in wastewater. This can be achieved using a tank with an inclined plate sedimentation structure, removing large particles through gravity settling. The anaerobic treatment tank 2 is a container that creates an anaerobic environment to promote the decomposition of organic matter. This can be achieved using a closed tank with a temperature control system, providing a reaction substrate for subsequent nitrogen and phosphorus removal. The cross-sectional change of the connecting pipe 5 refers to the contraction-expansion shape of the fluid channel's cross-sectional area. This can be achieved using a combination of conical and diffuser pipe sections, promoting gas-liquid mixing through velocity changes. The air inlet pipe 54 is located at the minimum cross-section, meaning the gas injection point is located in the narrowest area of ​​the connecting pipe 5. This can be achieved by creating radial through-holes in the pipe wall and welding short pipes, utilizing the negative pressure generated by the high-speed fluid to enhance gas intake efficiency.

[0042] Specifically, after large particulate impurities are removed in the pretreatment tank 1, the wastewater enters the anaerobic treatment tank 2, where denitrification is completed in the anoxic treatment tank 3. As the medium enters the aerobic treatment tank 4 through the third conduit 31, the cross-section of the connecting pipe 5 contracts, increasing the flow velocity. Gas is drawn in through the air inlet pipe 54 at the minimum cross-section, while the flow velocity decreases in the expansion section, forming a vortex and prolonging the gas-liquid contact time. This structure utilizes fluid kinetic energy to achieve self-priming aeration, avoiding the high energy consumption problem of traditional mechanical aeration. After nitrification is completed in the aerobic treatment tank 4, the mixed liquor is returned to the anoxic treatment tank 3 via the air guide pipe 6, forming an internal circulation.

[0043] Compared to existing technologies, traditional fixed-section connecting pipes 5 are prone to particle deposition due to sudden changes in flow velocity during sewage transport. The variable-diameter structure, however, accelerates the water flow by gradually narrowing to carry away suspended solids, while the expanding section decelerates to prevent air bubbles from escaping. Conventional aeration devices require separate aeration heads within the aerobic tank; this solution integrates the gas-liquid mixing process into connecting pipe 5, ensuring dissolved oxygen reaches saturation during the media transport stage. Existing technologies often place the gas injection point of the flute in the contraction section inlet; this solution places the air inlet pipe 54 at the minimum cross-section, utilizing the negative pressure generated by the maximum flow velocity to enhance gas intake.

[0044] Through the above technical solution, this application achieves simultaneous gas-liquid mixing and wastewater transportation, reducing the construction cost of the aeration system. The variable diameter connecting pipe 5 effectively prevents pipe blockage caused by suspended solids accumulation, reducing equipment maintenance frequency. The self-priming gas injection method eliminates the need for an external air compressor, saving energy consumption while achieving the same oxygen transfer efficiency. Dissolved oxygen is evenly distributed during the transportation stage, avoiding localized anoxic areas within the aerobic treatment tank 4 and improving the stability of the nitrification reaction.

[0045] As a preferred embodiment of this application, refer to Figure 1 An air guide pipe 6 connects the aerobic treatment tank 4 and the anoxic treatment tank 3. The air guide pipe 6 enters the lower middle part of the anoxic treatment tank 3 from the upper end of the aerobic treatment tank 4.

[0046] The gas delivery pipe 6 is a gas transmission channel connecting the aerobic treatment tank 4 and the anoxic treatment tank 3. It can be made of corrosion-resistant PVC or fiberglass pipe and is used to transport the oxygen-containing gas generated in the aerobic treatment tank 4 to the anoxic treatment tank 3. The upper inlet means that the inlet of the gas delivery pipe 6 is located in the top space of the aerobic treatment tank 4, and can be fixedly connected via a flange for easy collection of gas inside the tank. The lower middle inlet means that the outlet of the gas delivery pipe 6 is located in the lower middle region below the liquid surface in the anoxic treatment tank 3. This can be achieved by tilting the pipe in, causing the gas to form an upward bubble flow inside the anoxic treatment tank 3.

[0047] Specifically, during operation, the metabolic activities of microorganisms in the aerobic treatment tank 4 consume some of the oxygen introduced into the aerobic treatment tank 4 through the connecting pipe 5. The oxygen-rich gas accumulates at the top of the tank and is then transported to the lower middle part of the anoxic treatment tank 3 via the gas guide pipe 6. The gas is released as bubbles from the outlet of the gas guide pipe 6, forming an upward airflow within the anoxic treatment tank 3. As the bubbles rise, they come into contact with the mixed liquid inside the tank, consuming oxygen to promote denitrification. Simultaneously, the agitation effect of the bubbles enhances the mixing of sludge and wastewater. The inlet of the gas guide pipe 6 is located at the top of the aerobic treatment tank 4 to prevent backflow of liquid; the outlet is located in the lower middle part of the anoxic treatment tank 3 to ensure sufficient residence time for the bubbles in the anoxic zone to complete gas-liquid mass transfer.

[0048] Compared to existing technologies, traditional processes require a separate aeration device for the anoxic treatment tank 3 to ensure the dissolved oxygen needed for denitrification, resulting in complex equipment and increased energy consumption. This solution, however, achieves internal gas circulation between the aerobic treatment tank 4 and the anoxic treatment tank 3 through the air guide pipe 6, directly utilizing the low-oxygen-concentration gas generated in the aerobic section as the gas source for the anoxic section, eliminating the need for additional aeration equipment.

[0049] Through the above technical solution, this application effectively reduces the aeration energy consumption of the anoxic treatment section, while avoiding the risk of pipeline blockage caused by independent aeration equipment. The rising process of gas in the anoxic treatment tank 3 enhances the mixing effect of sludge and wastewater, promotes the reduction reaction of nitrate by denitrifying bacteria, and improves denitrification efficiency.

[0050] This application further proposes that the connecting pipe 5 includes a pipe wall, the cross-section of the channel inside the pipe wall first decreases and then increases along the medium flow direction, the connecting pipe 5 is provided with a flow guide cone 51, there is a medium channel between the flow guide cone 51 and the inner wall of the connecting pipe 5, the flow guide cone 51 is provided with a gas nozzle 52, the gas nozzle 52 extends along the medium flow direction, the outer side of the pipe wall is provided with a spiral air guide channel 53, and the air inlet pipe 54 is connected to the gas nozzle 52 through the spiral air guide channel 53.

[0051] The guide cone 51 refers to the conical structure set inside the connecting pipe 5, forming an annular medium channel with the pipe wall. It can be made of stainless steel, cast and welded together. The conical structure accelerates and diffuses the fluid. The spiral gas guide channel 53 refers to the spiral gas delivery path surrounding the outside of the pipe wall. It can be made by machining continuous grooves and covering them with a sealing cover. The spiral path extends the gas flow distance to enhance the gas-liquid contact time. The gas nozzle 52 refers to the nozzle installed at the front end of the guide cone 51 and arranged along the medium flow direction. It can be made of ceramic nozzle with a 0.5-2 mm orifice diameter, promoting the dispersion of bubbles in the high-speed flow field through directional injection.

[0052] Specifically, when the medium flows through the connecting pipe 5, it first enters a region with a gradually decreasing cross-section, forming a high-speed flow. The guide cone 51 forces the fluid to accelerate within the annular channel. After the gas enters the spiral gas guide channel 53 through the inlet pipe 54, it rotates along the spiral path to the gas nozzle 52, where the fluid is injected at the smallest cross-section where the medium velocity is highest. The gas is sheared at high speed to form microbubbles, and its velocity decreases as it enters the region with an expanding cross-section, prolonging the gas-liquid contact time. The cone angle of the guide cone 51 is controlled between 15 and 30 degrees to ensure that no eddies are generated during fluid acceleration. The ratio of the pitch of the spiral gas guide channel 53 to the diameter of the connecting pipe 5 is 1:3 to 1:5, allowing the gas to achieve pressure balance during transport.

[0053] Compared to existing technologies, traditional venturi tubes employ a single tapered and expanded structure, with the gas inlet located at the throat and directly exposed to the main fluid, making the nozzle susceptible to clogging by solid particles. This solution, however, utilizes a spiral gas guide channel 53 to create an independent gas delivery path, preventing impurities from entering the gas system. Simultaneously, the annular flow channel formed by the guide cone 51 and the tube wall ensures smooth medium flow, achieving efficient gas-liquid mixing while reducing the risk of clogging.

[0054] Through the above technical solution, this application effectively solves the technical problem of easy clogging of gas-liquid mixing device in the process of high suspended solids wastewater treatment, significantly extends the equipment maintenance cycle while maintaining oxygen mass transfer efficiency, and improves the uniformity of bubble distribution and reduces aeration energy consumption through the synergistic effect of spiral air guiding path and guide cone 51.

[0055] As a preferred embodiment of the aerobic treatment tank 4, refer to Figure 1 The aerobic treatment tank 4 is equipped with a stirring mechanism, which includes a drive motor 41. A stirring shaft 42 is rotatably connected inside the aerobic treatment tank 4. A stirring rod 43 is provided at the bottom of the stirring shaft 42. The output end of the drive motor 41 is fixedly connected to the stirring shaft 42. A drain pipe 44 is provided at the bottom of the aerobic treatment tank 4.

[0056] The stirring mechanism refers to a device that promotes the mixing of liquids within the tank through mechanical motion. Specifically, it can be implemented using a drive motor 41 to rotate the stirring shaft 42, with an impeller-type stirring rod 43 creating vortices to enhance dissolved oxygen diffusion. The drive motor 41 provides rotational power to the stirring shaft 42 and can be implemented using a combination of a variable frequency motor and a reducer, allowing for adjustment of the stirring intensity based on water quality. The stirring rod 43 is a mixing component fixed to the end of the stirring shaft 42, and can be implemented using a paddle-type or turbine-type structure to disrupt liquid stratification and increase the gas-liquid contact area. The drain pipe 44 is a fluid discharge channel located at the bottom of the tank, and can be implemented using a five-pipe structure with inclined flanges, allowing the treated water to drain by gravity.

[0057] Specifically, the drive motor 41 is rigidly connected to a vertically positioned stirring shaft 42 via a coupling. The stirring shaft 42 extends from the top of the aerobic treatment tank 4 to the bottom of the tank, with three sets of stirring rods 43 arranged radially at the end of the stirring shaft 42. When the drive motor 41 starts, the stirring rods 43 rotate at a set speed, causing the liquid inside the tank to circulate, promoting full contact between the activated sludge and the wastewater. The drain pipe 44 located at the bottom of the tank is eccentrically arranged, which avoids pipe blockage caused by sludge deposition during continuous stirring. The treated wastewater enters the next process through the drain pipe 44.

[0058] Compared to existing technologies, traditional aerobic treatment units rely on gas disturbance in the bottom aeration discs for mixing, resulting in dead zones and excessive energy consumption. This solution replaces traditional aeration mixing with mechanical stirring. An adjustable-speed stirring mechanism achieves liquid circulation throughout the entire tank, avoiding complex piping layouts in the aeration system and reducing power consumption per unit treatment capacity. Compared to fixed aeration devices, the dynamic flow field created by the rotating stirring rod 43 more effectively prevents activated sludge sedimentation.

[0059] Through the above technical solution, this application achieves uniform distribution of dissolved oxygen during aerobic treatment, ensuring sufficient contact between nitrifying bacteria and organic matter. Simultaneously, the shear force generated by mechanical stirring promotes biofilm renewal. The bottom drain pipe 44 remains unobstructed under continuous stirring, effectively solving the pipe blockage problem caused by sludge deposition during traditional static drainage and reducing equipment maintenance frequency.

[0060] As a preferred embodiment of the pretreatment tank 1, refer to Figure 1 The pretreatment tank 1 is a sedimentation tank. A sludge discharge pipe 12 is installed at the bottom of the pretreatment tank 1. A first conduit 11 is connected between the pretreatment tank 1 and the anaerobic treatment tank 2. A pump is installed on the first conduit 11.

[0061] The sedimentation tank refers to a tank that achieves solid-liquid separation through gravity settling. It can be implemented using a horizontal or vertical flow structure, with a conical hopper at the bottom to collect sediment. The sludge discharge pipe 12 is used to discharge settled sludge, and can be implemented using flanged steel pipes or UPVC pipes. A manual or electric gate valve is installed at the end of the pipe to control the sludge discharge cycle. The first conduit 11 is the liquid transport channel connecting the pretreatment tank 1 and the anaerobic treatment tank 2, and can be implemented using DN150-DN200 UPVC pipes. The pump is a power device used to regulate the liquid transport flow rate, and can be implemented using a submersible sewage pump or screw pump, with the flow rate controlled by a frequency converter to match the treatment requirements.

[0062] Specifically, after wastewater enters pretreatment tank 1, suspended solids are naturally separated to the bottom of the tank, and the clarified liquid is pumped to anaerobic treatment tank 2 through the first conduit 11. The settled sludge is periodically discharged to the sludge treatment unit through the sludge discharge pipe 12, effectively preventing siltation at the bottom of the tank. The pump configuration creates a controllable liquid transport path between pretreatment tank 1 and anaerobic treatment tank 2. By adjusting the pump power, the influent flow rate can be precisely controlled, ensuring a stable carbon source concentration in the subsequent anaerobic treatment stage. This structural combination forms a closed-loop material circulation system for the pretreatment stage, achieving simultaneous optimization of solid-liquid separation and flow control.

[0063] Compared to existing technologies, traditional pretreatment units often use bar screens to intercept large suspended solids, but these are ineffective at removing fine particulate matter, leading to increased load on subsequent biological treatment units. While some improved solutions employ cyclone separators to enhance solid-liquid separation efficiency, they suffer from drawbacks such as complex equipment and high energy consumption. This solution achieves efficient separation without power by using a sedimentation tank structure. Combined with periodic sludge discharge via sludge pipelines and pump flow control, it forms a low-energy pretreatment system that simplifies equipment while ensuring treatment stability.

[0064] Through the above technical solution, this application effectively solves the problem of reduced subsequent treatment efficiency caused by incomplete removal of suspended solids in the pretreatment stage. By combining the sedimentation tank with the controllable pumping system, the risk of blockage in the biochemical treatment unit is reduced, while timely cleaning of sludge and continuous operation of the treatment process are achieved.

[0065] As one specific embodiment of this application, refer to Figure 1 A second conduit 21 is connected between the anaerobic treatment tank 2 and the anoxic treatment tank 3. The two ends of the second conduit 21 are respectively connected to the upper middle part of the anaerobic treatment tank 2 and the lower middle part of the anoxic treatment tank 3.

[0066] The second conduit 21 is a fluid transport channel connecting the anaerobic treatment tank 2 and the anoxic treatment tank 3. This can be achieved by a height difference between the upper and lower sections, using gravity to drive the flow of the medium and promote the directional transport of phosphorus-releasing sludge from the anaerobic treatment tank 2 to the anoxic treatment tank 3. The upper-middle connection point of the anaerobic treatment tank 2 refers to the upper-middle region of the tank's media layer, specifically within 60%-70% of the tank's height. Its function is to preferentially discharge the liquid medium rich in volatile fatty acids, providing a carbon source for denitrification in the anoxic treatment tank 3. The lower-middle connection point of the anoxic treatment tank 3 refers to the lower-middle region of the tank's media layer, specifically within 30%-40% of the tank's height. Its function is to guide the medium into the anoxic zone in a counter-current direction, extending the sludge retention time and enhancing denitrification.

[0067] Specifically, the second conduit 21 is spatially offset between the upper part of the anaerobic treatment tank 2 and the lower part of the anoxic treatment tank 3, forming a media transport path from high to low. Inside the anaerobic treatment tank 2, after polyphosphate-accumulating bacteria release phosphate under anaerobic conditions, the volatile fatty acids accumulated in the liquid phase enter the second conduit 21 through the upper outlet and flow towards the lower inlet of the anoxic treatment tank 3 under gravity. After entering the anoxic treatment tank 3, the media comes into contact with denitrifying bacteria as it rises from the bottom of the tank. The carbon source is preferentially used for nitrate reduction, thus alleviating the competition for carbon sources between denitrification and phosphorus release in traditional processes. Simultaneously, the counter-current design at the lower inlet prolongs the residence time of sludge in the anoxic zone, preventing unreacted media from directly entering subsequent treatment units.

[0068] Compared to existing technologies, traditional split-type anaerobic and anoxic units use pumps or horizontal conduits for connection, resulting in uneven carbon source distribution and complex sludge return paths. This solution uses a staggered connection of the second conduit 21 to achieve directional flow of the medium without external power. At the same time, it utilizes spatial differences to optimize carbon source transfer efficiency and reduce fluctuations in nitrogen and phosphorus removal efficiency caused by carbon source competition.

[0069] Through the above technical solution, this application achieves precise matching of the carbon source between the phosphorus release products of the anaerobic stage and the denitrification requirements of the anoxic stage, effectively suppressing the competitive consumption of organic matter by denitrifying bacteria and polyphosphate-accumulating bacteria, and solving the problem of reduced treatment efficiency caused by the imbalance of carbon source distribution in traditional processes. At the same time, the countercurrent movement of the medium in the anoxic treatment tank 3 enhances the contact between sludge and liquid phase, reduces the risk of short-circuiting, and improves denitrification stability.

[0070] As a preferred example of this application, valves are provided on the first conduit 11, the second conduit 21 and the third conduit 31.

[0071] Valves are control components used to open, close, or regulate fluid flow. They can be gate valves, butterfly valves, or ball valves, and their opening degree can be adjusted manually or automatically to match the flow requirements of different treatment stages. Valves installed on conduits enable dynamic control of the media transport path. During the switching between anaerobic, anoxic, and aerobic units in wastewater treatment, the hydraulic retention time and sludge return ratio are optimized by adjusting the media flow rate between each unit.

[0072] Specifically, the first conduit 11 connects the pretreatment tank 1 to the anaerobic treatment tank 2, the second conduit 21 connects the anaerobic treatment tank 2 to the anoxic treatment tank 3, and the third conduit 31 connects the anoxic treatment tank 3 to the aerobic treatment tank 4. When wastewater is pumped from the pretreatment tank 1 to the anaerobic treatment tank 2, the initial load entering the anaerobic section can be controlled by adjusting the valve opening of the first conduit 11; the valve adjustment of the second conduit 21 helps to balance the sludge concentration in the anaerobic and anoxic sections; and the valve of the third conduit 31 coordinates the nitrification liquor return rate in the aerobic and anoxic sections. For example, when the influent water quality fluctuates, the operational stability of each treatment unit can be maintained by adjusting the valve opening in real time. In addition, the valves can also shut down specific units during equipment maintenance, preventing the entire system from shutting down.

[0073] Compared to existing technologies, traditional wastewater treatment devices typically employ fixed-flow conduits, making it impossible to dynamically adjust the media transfer between treatment units based on water quality changes. This can easily lead to uneven carbon source distribution or uncontrolled sludge return. This solution, however, achieves precise control of the media flow in each treatment stage by adding valves to key conduits. This effectively solves the problem of decreased nitrogen and phosphorus removal efficiency caused by mismatched hydraulic retention times in traditional processes, while also reducing the risk of pipe blockage due to sudden flow changes.

[0074] Through the above technical solution, this application can flexibly adjust the wastewater transfer rate between each treatment unit according to actual operating conditions, ensuring the coordinated operation of anaerobic phosphorus release, anoxic denitrification, and aerobic phosphorus uptake processes, and significantly improving nitrogen and phosphorus removal efficiency. Furthermore, the valve design reduces the frequency of equipment maintenance caused by excessive sludge accumulation and decreases the need for chemical reagents.

[0075] This application further proposes that the outer end of the intake pipe 54 is detachably connected to a filter element.

[0076] Detachable connection refers to the ability to fix and separate components through a separable structure. This can be achieved using threaded connections, snap-fit ​​connections, or quick-release couplings, facilitating the installation and removal of the filter element. The filter element refers to a porous media structure used to filter gaseous impurities. It can be made of polyester fiber layers, stainless steel mesh, or activated carbon composite materials, with filtration accuracy controllable within the range of 10-100 micrometers to intercept particulate matter in the air.

[0077] Specifically, the filter element is installed at the air inlet port of the air inlet pipe 54, forming a sealed connection with the pipe body via a detachable connection structure. When gas enters the connecting pipe 5 through the air inlet pipe 54, the filter element intercepts dust, microorganisms, and suspended particles in the gas, preventing impurities from entering the gas nozzle 52 and causing blockage. When the filter element becomes clogged or contaminated due to long-term use, it can be disassembled for cleaning or replacement via the detachable connection structure, without needing to replace the entire air inlet pipe 54.

[0078] Compared to existing technologies, traditional gas-liquid mixing devices often use fixed filters at the air inlet. Replacing the filter requires disassembling the entire pipeline, resulting in low maintenance efficiency and potential equipment damage. Furthermore, fixed filters often require chemical flushing when clogged, which can lead to secondary pollution. This solution achieves rapid filter maintenance through a detachable structure, while avoiding the use of chemical cleaning agents.

[0079] Through the above technical solutions, this application effectively prevents impurities from entering the aeration unit during gas transportation and reduces the risk of clogging of the gas nozzle 52; the modular filter element design shortens maintenance operation time, avoids the impact of equipment downtime on the continuity of sewage treatment, and reduces the additional costs incurred due to filter element maintenance.

[0080] For any parts not mentioned in this utility model, existing technologies can be used or referenced.

[0081] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0082] The above description is merely an embodiment of this utility model and is not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this utility model should be included within the scope of the claims of this utility model.

Claims

1. A sewage treatment multi-stage sedimentation and phosphorus removal integrated device, characterized in that, It includes a pretreatment tank (1), an anaerobic treatment tank (2), an anoxic treatment tank (3), and an aerobic treatment tank (4) connected in sequence; A third conduit (31) connects the anoxic treatment tank (3) and the aerobic treatment tank (4). The third conduit (31) connects from the upper part of the anoxic treatment tank (3) to the lower part of the aerobic treatment tank (4). A connecting pipe (5) is provided on the third conduit (31). The cross-sectional area of ​​the connecting pipe (5) decreases and then increases along the direction of medium flow. An air inlet pipe (54) is provided on the side wall of the connecting pipe (5) and is located at the minimum cross-sectional area of ​​the connecting pipe (5).

2. The sewage treatment multi-stage sedimentation and dephosphorization integrated device according to claim 1, characterized in that, An air guide pipe (6) is connected between the aerobic treatment tank (4) and the anoxic treatment tank (3). The air guide pipe (6) is connected from the upper end of the aerobic treatment tank (4) to the lower middle part of the anoxic treatment tank (3).

3. The sewage treatment multi-stage sedimentation and dephosphorization integrated device according to claim 1, characterized in that, The connecting pipe (5) includes a pipe wall, the cross-section of the channel inside the pipe wall first decreases and then increases along the medium flow direction, the connecting pipe (5) is provided with a flow guide cone (51), there is a medium channel between the flow guide cone (51) and the inner wall of the connecting pipe (5), the flow guide cone (51) is provided with a gas nozzle (52), the gas nozzle (52) extends along the medium flow direction, the outer side of the pipe wall is provided with a spiral air guide channel (53), and the air inlet pipe (54) is connected to the gas nozzle (52) through the spiral air guide channel (53).

4. The sewage treatment multi-stage sedimentation and dephosphorization integrated device according to claim 1, characterized in that, The aerobic treatment tank (4) is equipped with a stirring mechanism, which includes a drive motor (41). A stirring shaft (42) is rotatably connected inside the aerobic treatment tank (4). A stirring rod (43) is provided at the bottom of the stirring shaft (42). The output end of the drive motor (41) is fixedly connected to the stirring shaft (42). A drain pipe (44) is provided at the bottom of the aerobic treatment tank (4).

5. The sewage treatment multi-stage sedimentation and dephosphorization integrated device according to claim 3, characterized in that, The pretreatment tank (1) is a sedimentation tank. The bottom of the pretreatment tank (1) is provided with a sludge discharge pipe (12). The pretreatment tank (1) is connected to the anaerobic treatment tank (2) by a first conduit (11), and a pump is provided on the first conduit (11).

6. The sewage treatment multi-stage sedimentation and dephosphorization integrated device according to claim 5, characterized in that, A second conduit (21) connects the anaerobic treatment tank (2) and the anoxic treatment tank (3). The two ends of the second conduit (21) are respectively connected to the upper middle part of the anaerobic treatment tank (2) and the lower middle part of the anoxic treatment tank (3).

7. The sewage treatment multi-stage sedimentation and dephosphorization integrated device according to claim 6, characterized in that, Valves are provided on the first conduit (11), the second conduit (21), and the third conduit (31).

8. The sewage treatment multi-stage sedimentation and dephosphorization integrated device according to claim 3, characterized in that, The air intake pipe (54) has a filter element detachably connected to its outer end.

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