A low-energy, non-powered backflow, integrated sewage treatment device

Abstract

The application relates to the technical field of sewage treatment, in particular to a low-energy-consumption, non-powered backflow and integrated sewage treatment device, which comprises a pretreatment unit, a multistage biological reaction unit, an inclined tube sedimentation unit and a depth filtration unit which are sequentially communicated, the multistage biological reaction unit is sequentially separated into an anaerobic zone, an anoxic zone, an aerobic zone, a post-anoxic zone and a terminal aerobic zone along a water flow direction, the pool bottom elevations of the zones are gradually lowered along the water flow direction, and gravity flow is realized by means of water level difference; the low-energy-consumption, non-powered backflow and integrated sewage treatment device integrates the multiple functions of water blocking grading, aeration oxygenation, directional flow pushing, active confluence, nitrification liquid backflow and mud-water separation on a single component by means of a double-cavity partition wall, the aeration, flow pushing and gas lifting backflow share the same gas source, energy is fully reused, and multiple sets of equipment such as an independent backflow pump, an external mud-water separator and a pool bottom agitator are omitted.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a low-energy-consumption, non-powered backflow, integrated wastewater treatment device. Background Technology

[0002] With the advancement of rural sewage treatment and decentralized point source pollution control in my country, tiered integrated sewage treatment equipment relies on water level differences to achieve gravity self-propulsion, which can reduce the configuration of power equipment and lower daily operation and maintenance costs. It has become one of the mainstream technical routes for the treatment of rural domestic sewage, decentralized sewage in towns and villages, and small-scale aquaculture wastewater. However, in actual engineering applications, there are still some common technical problems that need to be optimized.

[0003] Regarding aeration mixing and flow patterns within the tank, conventional stepped tanks rely solely on top overflow to achieve horizontal flow, naturally exhibiting a flow stratification phenomenon of "fast surface flow and slow bottom flow." The accompanying bottom microporous aeration system primarily relies on vertical mixing, resulting in weak horizontal flow propulsion. Localized low-velocity zones easily form in areas such as tank corners and the back of partition walls, where sludge and suspended filler tend to accumulate, requiring regular cleaning and maintenance, which to some extent reduces the effective volume utilization rate of the reaction tank.

[0004] Regarding the internal reflux system for nitrified liquor, existing solutions mostly employ simple airlift pipes to achieve internal reflux of nitrified liquor for biological denitrification. However, this approach has three main shortcomings in actual operation: First, the airlift reflux process easily carries a large amount of activated sludge into the anoxic zone, additionally consuming the system's limited carbon source and negatively impacting denitrification efficiency. Furthermore, adding external sludge separators, sedimentation tanks, and other facilities increases land area and equipment costs, weakening the integrated advantages of the integrated unit. Second, the airlift reflux flow rate with fixed openings exhibits a non-linear variation with aeration volume. The reflux flow rate is low under low load conditions and increases significantly with high load conditions, resulting in insufficient operational stability. Using electrically controlled valves and online sensors for regulation presents problems such as high equipment costs and numerous potential failure points, which are incompatible with the low-maintenance requirements of remote and dispersed scenarios. Third, multi-point airlift reflux devices primarily pump from surrounding water bodies, easily forming localized short-circuiting flows. The efficiency of water bodies in the middle and corners of the tank participating in the reflux circulation is low, and the stability of the denitrification effect needs further improvement.

[0005] Therefore, we propose a low-energy-consumption, non-powered backflow, integrated wastewater treatment device. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a low-energy, non-powered backflow, integrated wastewater treatment device, comprising a pretreatment unit, a multi-stage step biological reaction unit, an inclined tube sedimentation unit, and a deep filtration unit connected in sequence. The multi-stage step biological reaction unit is sequentially divided into an anaerobic zone, an anoxic zone, an aerobic zone, a post-anoxic zone, and a terminal aerobic zone along the water flow direction. The bottom elevation of each zone decreases progressively along the water flow direction, achieving gravity flow by relying on the water level difference. A double-cavity partition wall is provided between the anoxic zone and the aerobic zone. A sawtooth overflow channel is provided at the top of the double-cavity partition wall. A horizontal partition plate is fixedly provided on the inner side of the double-cavity partition wall. The interior of the double-cavity partition wall is completely separated into a lower aeration chamber and an upper backflow chamber by the partition plate. The aeration chamber has oxygenation mixing holes and flow-generating confluence holes on its upper and lower sides facing the aerobic zone. The oxygenation mixing holes and flow-generating confluence holes share the same aeration air source. The return chamber is equipped with multiple return cylinders. The lower side wall of the return cylinder has a tangential inlet facing the aerobic zone. The top of the return cylinder extends upward through the top surface of the sawtooth overflow channel, and the side wall has a return outlet facing the anoxic zone. The elevation of the return outlet is higher than the normal operating water level of the anoxic zone.

[0007] In some embodiments, the axis of the flow-generating confluence holes is inclined forward at 15°-20° along the water flow direction, and the flow-generating confluence holes are evenly arranged along the width of the pool. The holes directly below each return cylinder are the main flow-generating holes, and the holes between adjacent return cylinders and at the two side corners of the pool are the side confluence holes.

[0008] In some embodiments, the axis of the side confluence hole is horizontally deflected by 15°-20° towards the nearest return cylinder, which is used to guide the bottom water to converge directly below the return cylinder while flowing forward. The axis of the main push flow hole is arranged along the front of the water flow, which is used to drive the bottom water to flow forward and flush the sediment at the bottom of the pool.

[0009] In some embodiments, the oxygenation mixing hole is located on the upper side wall of the aeration chamber facing the aerobic zone, and the axis of the oxygenation mixing hole is arranged obliquely upward at 45°-60°. The number of holes is greater than that of the flow-pushing confluence holes, and the position of the oxygenation mixing hole is directly opposite the water drop trajectory of the sawtooth overflow channel.

[0010] In some embodiments, a spiral guide vane is provided on the lower inner side of the reflux cylinder, and the tangential water inlet is opened along the tangential direction of the inner wall of the reflux cylinder, with its inner side smoothly connected to the starting end of the spiral guide vane.

[0011] In some embodiments, the return cylinder is provided with an air lift nozzle, which is located above the spiral guide vanes and at the center of the cylinder. The air outlet direction is coaxial with the cylinder axis and perpendicular to the upward direction. The air lift nozzle is connected to the main aeration air source of the aeration chamber through a branch pipe.

[0012] In some embodiments, the reflux cylinder is provided with a plurality of staggered baffles, the baffles being located above the air lift nozzle and arranged at an angle downwards within the reflux cylinder.

[0013] In some embodiments, the reflux cylinder is further provided with an adaptive throttling structure, including an annular float, a vertical connecting rod, an arc-shaped baffle, guide ribs, and a lower limit block. The annular float floats on the surface of the gas-liquid mixture inside the reflux cylinder and is connected to the arc-shaped baffle via the vertical connecting rod. The arc-shaped baffle fits against the inner wall of the cylinder and covers the reflux outlet. The guide ribs are fixedly installed on the inner wall of the reflux cylinder. A matching guide slot is provided on the outer side of the annular float. The lower limit block is fixedly installed at the bottom of the guide ribs to limit the lowest falling position of the annular float and retain the basic flow gap.

[0014] In some embodiments, mounting blocks are fixedly provided on the upper and lower sides of the reflux cavity, and a through hole for embedding the reflux cylinder is opened in the middle of the mounting block. The reflux cylinder is a prefabricated round tube, which is modularly embedded in the reserved through hole of the mounting block.

[0015] In some embodiments, the diameter of the flow manifold is larger than the diameter of the oxygen mixing hole.

[0016] This invention has at least the following beneficial effects: 1. The double-cavity partition wall integrates multiple functions such as water blocking and grading, aeration and oxygenation, directional flow, active flow convergence, nitrification liquid return, and mud-water separation on a single component. Furthermore, aeration, flow, and air lift return share the same air source, making full use of energy. This eliminates the need for multiple sets of equipment such as independent return pumps, external mud-water separators, and bottom agitators, which not only improves the integration of the device but also significantly reduces equipment costs and operating energy consumption. 2. Tangential water inlet combined with shaftless spiral blades fixed to the wall can form a stable and orderly swirling field. Combined with subsequent baffles, it forms a two-stage sludge-water separation system, which can efficiently intercept activated sludge in the return liquid and prevent aerobic sludge from entering the anoxic zone with the return liquid and consuming valuable carbon sources. The separation process is driven entirely by the kinetic energy of the inlet water itself, without the need for additional power equipment. It effectively improves the denitrification efficiency of low carbon source wastewater with zero additional energy consumption. 3. The design adopts a layered perforation pattern. The bottom layer of flow-promoting and converging holes activates the bottom water, eliminates sludge accumulation and blind spots in the return flow, while the upper layer of oxygenation and mixing holes enhances vertical circulation and influent mixing. The flow pattern in the entire pool is uniform and orderly. With the adaptive throttling structure, the return flow can be automatically matched according to the aeration intensity. No electrical control components or manual adjustment are required. The system has strong stability under all operating conditions, which greatly reduces the difficulty of operation and maintenance. It is suitable for decentralized, low-maintenance sewage treatment scenarios in rural areas and towns. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the structure in the anoxic and aerobic zones of the present invention; Figure 3 This is a schematic diagram of the double-cavity partition wall structure of the present invention; Figure 4 This is a schematic diagram of the double-cavity partition wall structure from another orientation; Figure 5 This is a schematic diagram of the front cross-sectional structure of the double-cavity partition wall of the present invention; Figure 6 This is a partial side sectional view of the double-cavity partition wall structure of the present invention; Figure 7 This is a schematic diagram of the direction of the flow-generating confluence hole in the present invention; Figure 8 This is a schematic diagram of the structure at the reflux cylinder of the present invention; Figure 9 This is a schematic diagram of the internal structure of the reflux cylinder of the present invention; Figure 10 This is a schematic diagram of the adaptive throttling structure of the present invention.

[0018] In the diagram: 1-Pretreatment unit; 2-Multi-stage step-by-step biological reaction unit; 21-Anaerobic zone; 22-Anoxic zone; 23-Aerobic zone; 24-Post-anoxic zone; 25-Terminal aerobic zone; 3-Inclined tube sedimentation unit; 4-Deep filtration unit; 5-Double-cavity partition wall; 6-Sawtooth overflow trough; 7-Separator plate; 8-Aeration chamber; 9-Recirculation chamber; 10-Oxygenation mixing hole; 11-Push flow confluence hole; 111-Main push flow hole; 112-Side confluence hole; 12-Recirculation cylinder; 13-Tangential inlet; 14-Recirculation outlet; 15-Helical guide vane; 16-Air lift nozzle; 17-Baffle plate; 18-Adaptive throttling structure; 181-Annular float; 182-Vertical connecting rod; 183-Arc-surface shielding baffle; 184-Guide rib; 185-Lower limit block; 19-Installation block. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: Please refer to Figures 1-10The present invention provides a technical solution: a low-energy, non-powered backflow, integrated sewage treatment device, comprising a pretreatment unit 1, a multi-stage step biological reaction unit 2, an inclined tube sedimentation unit 3 and a deep filtration unit 4 connected in sequence. The multi-stage step biological reaction unit 2 is divided into an anaerobic zone 21, an anoxic zone 22, an aerobic zone 23, a post-anoxic zone 24 and a terminal aerobic zone 25 in sequence along the water flow direction. The bottom elevation of each zone decreases step by step along the water flow direction, and gravity flow is achieved by relying on the water level difference. The pretreatment unit 1 is used for front-end physical treatment of the incoming water. It sequentially passes the water through a screen to intercept large floating and suspended solids, a grit removal unit to remove inorganic sand particles, and a regulating tank to balance water quality and quantity, preventing peak inflows from impacting the subsequent biological system. The multi-stage biological reaction unit 2 is the core treatment unit of the device. Relying on the gradually decreasing bottom elevation of the tank to create a natural water level difference, the main water flow can flow by gravity without additional power, sequentially completing a series of biological processes including hydrolysis acidification, denitrification, organic matter degradation and nitrification, deep denitrification, and terminal ammonia nitrogen stripping. The core carrier for pollutant removal is the inclined tube sedimentation unit 3, which uses the principle of shallow sedimentation to separate mud and water, and intercepts and settles the activated sludge and detached biofilm carried in the biochemical effluent to ensure that the concentration of suspended solids in the effluent meets the standards. The deep filtration unit 4 further intercepts fine suspended solids and trace dissolved pollutants in the effluent through composite filter media, thereby improving the stability of the final effluent water quality. The specific structure and operation mode of the pretreatment unit 1, the inclined tube sedimentation unit 3 and the deep filtration unit 4 are all conventional technical means well known to those skilled in the art. This part is the prior art and will not be described in detail here.

[0021] A double-cavity partition wall 5 is provided between the anoxic zone 22 and the aerobic zone 23. A sawtooth overflow groove 6 is provided at the top of the double-cavity partition wall 5. A horizontal partition plate 7 is fixedly provided on the inner side of the double-cavity partition wall 5. The inner side of the double-cavity partition wall 5 is completely separated into a lower aeration chamber 8 and an upper return chamber 9 by the partition plate 7. The double-cavity partition wall 5 serves a dual function of water blocking and grading, as well as functional integration. It acts as a vertical separator between the anoxic zone 22 and the aerobic zone 23, achieving water level difference and functional zoning between the two zones. Furthermore, it integrates multiple functions such as aeration, flow propulsion, recirculation, and separation within the wall, eliminating the need for separate aeration pipes, recirculation pumps, and separation equipment within the tank. This improves the overall integration of the device and reduces dead water areas within the tank. The horizontal partition plate 7 is tightly connected to the inner wall of the partition wall using a sealed and fixed design, completely blocking the flow of gas and water between the upper and lower cavities and preventing compressed air from the lower aeration chamber 8 from directly entering the upper recirculation chamber. 9. To prevent the liquid level balance of the airlift return from being disrupted and to ensure that the two systems operate independently without interference, the lower aeration chamber 8 is a wide, sealed chamber that runs through the entire width of the partition wall. This allows for the uniform distribution of compressed air and ensures that the air pressure and air volume of each nozzle are basically consistent along the width of the pool. This avoids problems such as uneven air volume at both ends and insufficient aeration in some areas. The upper return chamber 9 is used to accommodate and fix multiple sets of return cylinders 12, providing stable installation support for the return cylinders 12. At the same time, it isolates each set of return cylinders 12 from the external water body, leaving only the inlet and outlet channels to ensure the sealing of the return process.

[0022] The aeration chamber 8 has oxygen mixing holes 10 and flow mixing holes 11 on the upper and lower sides of the sidewall facing the aerobic zone 23, respectively. The oxygen mixing holes 10 and the flow mixing holes 11 share the same aeration gas source. Compressed air is delivered to the aeration chamber 8 by an external pump and then released into the aerobic zone 23 through two rows of nozzles. The same air source drives the three functions of oxygenation, flow propulsion, and flow convergence simultaneously, eliminating the need for separate air supply systems. This simplifies pipeline layout and reduces equipment costs and operating energy consumption. As the gas is ejected at high speed from the nozzles, it drives a large amount of surrounding water to move synchronously through the jet entrainment effect. A small amount of gas kinetic energy can drive a large area of ​​water flow, resulting in higher energy utilization than conventional decentralized aeration devices. The two rows of nozzles are arranged vertically in layers, each corresponding to a different water layer and functional positioning. They complement each other in space and jointly construct a three-dimensional flow field structure, avoiding the defect that a single row of aeration can only affect a single water layer.

[0023] The reflux chamber 9 is equipped with multiple reflux cylinders 12. The lower side wall of the reflux cylinder 12 is provided with a tangential inlet 13 facing the aerobic zone 23. The top of the reflux cylinder 12 extends upward through the top surface of the sawtooth overflow channel 6 and the side wall is provided with a reflux outlet 14 facing the anoxic zone 22. The elevation of the reflux outlet 14 is higher than the normal operating water level of the anoxic zone 22.

[0024] Multiple return cylinders 12 are evenly arranged along the width of the pool, enabling simultaneous nitrification liquid suction and return at multiple points in the aerobic zone 23. This avoids uneven flow field and short-circuiting problems caused by single-point return, expanding the coverage of the return. The return cylinder 12 serves as an independent carrier for airlift return and sludge-water separation, with all internal functional components integrated inside the cylinder, forming an independent functional unit. This facilitates prefabrication and on-site installation. The tangential inlet 13 faces the aerobic zone 23, directly communicating with the water in the aerobic zone 23. The nitrified liquid in the aerobic zone 23 enters the cylinder through this inlet under the action of airlift suction. The side-entry water intake method allows for control of the water intake height, avoiding the sediment layer at the bottom of the pool and drawing water from the middle and lower water layers with lower sludge concentration. This reduces the sludge content of the return liquid from the source, lessening the load on the subsequent separation structure. The top of the return cylinder 12 extends upward through the top surface of the sawtooth overflow trough 6, allowing the return outlet 14 to be positioned above the water level of the anoxic zone 22. This ensures that the return liquid can flow into the anoxic zone 22 by gravity without the need for additional transport power. At the same time, the return outlet 14 is positioned above the liquid surface, preventing water from the anoxic zone 22 from flowing back into the return cylinder 12, ensuring the unidirectionality of the return flow and stable and reliable operation.

[0025] The axis of the flow-generating confluence hole 11 is inclined forward at 15°-20° along the direction of water flow. The flow-generating confluence holes 11 are evenly arranged along the width of the pool. Among them, the hole directly below each return cylinder 12 is the main flow-generating hole 111, and the holes between adjacent return cylinders 12 and at the corners of both sides of the pool are side flow-generating holes 112.

[0026] The flow-generating manifold 11 is arranged close to the bottom of the pool, and its forward-tilted angle allows the ejected gas-liquid mixture to extend forward along the bottom of the pool, directly acting on the bottom water where sludge is most likely to accumulate. This breaks the stratification phenomenon of "fast surface flow and slow bottom flow" in the stepped pool, driving the bottom water and the deposited sludge and packing material to flow forward synchronously, solving the problem of sludge accumulation and packing material compaction at the bottom of the pool. The evenly distributed holes along the width of the pool ensure that the bottom water receives uniform forward thrust throughout the entire width direction, avoiding dead zones with excessively low flow velocities. The flow-generating and converging holes 11 are divided into two types: main flow-generating holes 111 and side flow-generating holes 112. This is a functional zoning design based on the position of the upper return cylinder 12. The main flow-generating holes 111, which are directly below the return cylinder 12, undertake the main task of forward flow-generating and ensure the forward flow momentum of the main water flow. The side flow-generating holes 112, located in the gaps and corners, undertake the additional function of lateral flow-generating in addition to flow-generating. The two types of holes work together to achieve the dual effects of longitudinal flow-generating and lateral flow-generating without adding additional equipment.

[0027] The axis of the side confluence hole 112 is horizontally deflected by 15°-20° towards the nearest return cylinder 12, which is used to guide the bottom water to converge directly below the return cylinder 12 while flowing forward. The axis of the main push flow hole 111 is arranged along the front of the water flow, which is used to drive the bottom water to flow forward and flush the sediment at the bottom of the pool.

[0028] The horizontal deflection angle of the side confluence orifice 112 gives the jet it ejects both a forward longitudinal velocity and a lateral velocity toward the return cylinder 12. Under the jet entrainment effect, a large area of ​​the surrounding bottom water will be given a slow lateral drift velocity, causing the water to gradually converge toward the position directly below the nearest return cylinder 12 as it flows forward. This flow field design does not require any flow guiding components in the pool; it can be achieved simply by changing the drilling angle of the nozzle. The processing cost is almost zero, yet it can effectively guide water from corners, gaps, and other areas that are originally difficult to participate in the return flow, gradually converging into the suction range of the return cylinder 12, eliminating blind spots in the return circulation, and increasing the effective reaction volume ratio of the aerobic zone 23. The main pusher orifice 111 sprays air along the front, forming a longitudinal thrust, directly flushing the sedimented sludge and packing material at the bottom of the pool, preventing sludge from accumulating and anaerobicly decaying at the bottom of the pool for a long time, ensuring that the entire bottom of the pool is in a flowing state, and significantly extending the cleaning and maintenance cycle of the equipment.

[0029] The oxygenation mixing hole 10 is located on the upper side wall of the aeration chamber 8 facing the aerobic zone 23, and the axis of the oxygenation mixing hole 10 is arranged at an angle of 45°-60° upward. The number of holes is greater than that of the flow-pushing confluence hole 11. The position of the oxygenation mixing hole 10 is directly opposite the water drop trajectory of the sawtooth overflow channel 6.

[0030] The oxygenation mixing hole 10 is located in the lower middle water layer of the aerobic zone 23. Its upward-sloping spray angle significantly extends the rising distance of the bubbles in the water, increasing the gas-liquid contact time and effectively improving oxygen transfer efficiency and oxygenation capacity. A greater number of holes can form a denser bubble cluster, ensuring the overall dissolved oxygen supply to the aerobic zone 23 and meeting the needs of aerobic microorganisms for organic matter degradation and nitrification. The oxygenation mixing hole 10 is directly opposite the droplet position of the top sawtooth overflow trough 6. The rising gas-liquid flow from the hole can directly impact the incoming water flow falling from the overflow trough, breaking up and fragmenting the concentrated falling water flow, allowing the incoming water to mix with the existing nitrification liquid in the tank. The activated sludge is fully mixed in a short time, avoiding concentrated short-flow of influent and improving the utilization efficiency of carbon sources. It is especially suitable for the treatment of low-carbon wastewater. At the same time, a large number of upward-sloping bubbles continuously rise, which will drive the entire aerobic zone 23 to form a large-scale vertical circulation. This will continuously lift the bottom water to the middle and upper layers, while the surface water will continuously sink to replenish it, forming a continuous up-and-down rotation. This vertical circulation can transfer the lateral flow carried by the bottom water to the height of the inlet of the return cylinder 12, so that the water flow gathered at the bottom can smoothly reach the suction range of the return cylinder 12, realizing a smooth connection between the bottom push flow and the middle layer return water suction.

[0031] A spiral guide vane 15 is provided on the lower inner side of the return cylinder 12, and a tangential inlet 13 is opened along the tangential direction of the inner wall of the return cylinder 12, with its inner side smoothly connected to the starting end of the spiral guide vane 15.

[0032] The tangential inlet design allows the water to naturally possess initial momentum for rotation along the cylinder wall upon entering, forming an initial vortex without additional power. Guided by the regular spiral guide vanes 15, the water flow quickly forms a stable and uniform upward rotating flow field, avoiding the turbulence problems caused by direct inlet flow. The spiral guide vanes 15 are arranged circumferentially along the cylinder wall and smoothly connect with the tangential inlet 13. After entering, the water flows smoothly upward along the spiral trajectory of the vanes. The centrifugal force of the vortex continues to act on the sludge particles in the water as the water rises, causing the denser sludge particles to... The particles gradually move towards the cylinder wall, eventually adhering to the inner wall and sliding down the wall under gravity. Finally, they fall back from the tangential inlet 13 to the aerobic zone 23, completing the first-stage mud-water separation process. This cyclone separation, driven by the kinetic energy of the incoming water, does not require additional power equipment and does not consume additional energy. It is a recycling of the kinetic energy of the incoming water. Moreover, the larger the inlet flow rate and the faster the flow velocity, the stronger the centrifugal force of the cyclone and the better the separation effect. It can automatically follow the operating load to synchronously enhance the separation capacity, forming a natural adaptation relationship with the load changes of the system.

[0033] The return cylinder 12 is equipped with an air lift nozzle 16, which is located above the spiral guide vane 15 and at the center of the cylinder. The air outlet direction is coaxial with the cylinder axis and perpendicular to the upward direction. The air lift nozzle 16 is connected to the main aeration air source of the aeration chamber 8 through a branch pipe.

[0034] The air-lift nozzle 16 is the power source for automatically lifting the nitrified liquid. Compressed air is ejected from the nozzle, forming a large number of tiny bubbles. As the bubbles rise, they mix with the surrounding water, forming a gas-liquid mixture with a density much lower than that of the water outside the cylinder. The static pressure difference generated by the density difference between the liquid inside and outside the cylinder can drive the water inside the cylinder to rise continuously and finally flow out from the return outlet 14. No electric lifting equipment is required throughout the process. The return liquid can be transported by compressed air alone, resulting in extremely low energy consumption. The air nozzle is positioned at the center of the cylinder and sprays air vertically upwards, creating a uniform axial upward flow at the cylinder's axis. This results in more uniform gas-liquid mixing within the cylinder, optimizing the airlift efficiency. Simultaneously, the central air distribution avoids direct impact on the surrounding swirling flow field, preventing the disruption of the swirling flow and reduced separation efficiency that can occur with tangential air distribution. Instead, it creates a low-pressure zone at the center of the cylinder, indirectly enhancing the centrifugal effect of the peripheral swirling flow. This achieves a synergistic effect between airlift and swirling separation. The airlift nozzle 16 shares the same main aeration air source as the lower nozzle, further improving energy reuse and simplifying the system's piping configuration.

[0035] The reflux cylinder 12 is provided with a plurality of staggered baffles 17, which are located above the air lift nozzle 16 and are arranged at an angle downward inside the reflux cylinder 12.

[0036] After primary cyclone separation, the water carrying a small amount of fine sludge particles continues to rise and enters the separation zone of baffle 17. The staggered arrangement of the baffles 17 requires the water to constantly change its flow direction during its ascent, repeatedly impacting the inclined plate surface. Under inertia, the fine sludge particles in the water flow detach from the water flow, impacting and adhering to the baffles 17. Gradually accumulating, they slide down the inclined plate surface under gravity, eventually falling back to the lower part of the cylinder and returning to the aerobic zone 23 from the tangential inlet 13, completing the secondary sludge-water separation. The downward-arranged plates provide a smooth downward channel for the settling sludge, preventing sludge from accumulating and caking on the plates, ensuring long-term stable separation performance. The baffle plate 17, as a secondary separation method, can further retain fine sludge particles that cannot be removed by cyclone separation, complementing the primary cyclone separation. The synergistic effect of the two-stage separation can significantly improve the sludge retention rate of the return liquid, significantly reduce the amount of sludge returned to the anoxic zone 22, prevent aerobic sludge from consuming the carbon source of the anoxic zone 22, and effectively improve the denitrification efficiency of the system.

[0037] The reflux cylinder 12 is also equipped with an adaptive throttling structure 18, including an annular float 181, a vertical connecting rod 182, an arc-shaped baffle 183, a guide rib 184, and a lower limit block 185. The annular float 181 floats on the gas-liquid mixture surface inside the reflux cylinder 12 and is connected to the arc-shaped baffle 183 through the vertical connecting rod 182. The arc-shaped baffle 183 fits against the inner wall of the cylinder and covers the reflux outlet 14. The guide rib 184 is fixedly installed on the inner side wall of the reflux cylinder 12. A matching guide slot is opened on the outer side of the annular float 181. The lower limit block 185 is fixedly installed at the bottom of the guide rib 184 to limit the lowest falling position of the annular float 181 and retain the basic flow passage.

[0038] The adaptive throttling structure 18 is driven entirely by the liquid level changes of the airlift itself, requiring no electronic sensors, electric actuators, or external power. Its simple structure and low failure points make it suitable for the low-maintenance requirements of distributed sites. When the system's influent load increases, the aeration intensity increases accordingly, increasing the air output of the airlift nozzle 16, raising the proportion of bubbles in the cylinder, further reducing the density of the gas-liquid mixture, and increasing the height of the liquid level rise in the cylinder. At this time, the annular float 181 rises synchronously with the liquid level, driving the arc-shaped baffle 183 upwards via the vertical connecting rod 182, automatically increasing the flow area of ​​the return outlet 14 and thus increasing the return flow rate to match the greater nitrification liquid return demand under high loads. Conversely, when the influent load decreases and the aeration intensity decreases, the liquid level in the cylinder drops, and the annular float 181 drives the baffle to fall synchronously, reducing the flow area of ​​the return outlet 14 and automatically decreasing the return flow rate. To avoid carbon source waste caused by excessive return flow under low load, the guide rib 184 and the guide groove provide guidance and limit for the up and down movement of the annular float 181, preventing the float from deflecting or getting stuck during the lifting and lowering process. This ensures that the arc-shaped shielding baffle 183 always fits tightly against the inner wall of the cylinder, ensuring stable sealing performance and reliable adjustment accuracy. The lower limit block 185 can limit the lowest falling position of the float. Even under extremely low load and very small gas volume conditions, the return outlet 14 always retains a basic flow gap to ensure a minimum return flow, prevent complete interruption of return flow, and ensure the basic operational stability of the denitrification system. This adaptive structure can not only automatically match different operating loads, but also stabilize the liquid level in the cylinder, preventing excessive turbulence of the liquid surface and stirring up the settled sludge when the gas volume is high. This indirectly ensures the stability of the two-stage mud-water separation effect and forms a deep synergy with the separation structure.

[0039] Mounting blocks 19 are fixedly installed on the upper and lower sides of the reflux chamber 9. A through hole for embedding the reflux cylinder 12 is opened in the middle of the mounting block 19. The reflux cylinder 12 is a prefabricated round tube, which is modularly embedded in the reserved through hole of the mounting block 19.

[0040] The mounting blocks 19, positioned at the top and bottom, provide fixed support for the return cylinder 12 from two locations, ensuring a stable vertical posture within the cavity. This prevents displacement and swaying caused by water flow impact and airflow vibration, guaranteeing the operational stability of the internal components. The pre-drilled through holes on the mounting blocks 19 precisely match the outer diameter of the return cylinder 12, enabling quick insertion and removal of the cylinder. During on-site construction, the prefabricated return cylinder 12 can be simply inserted into the through holes and sealed around the perimeter, significantly reducing the difficulty and time required for on-site installation. The modular design using prefabricated round tubes allows for the pre-assembly and debugging of all internal components in the factory, ensuring processing and fitting precision and avoiding dimensional errors and quality instability issues caused by on-site fabrication. Furthermore, during later maintenance, if internal components experience wear, scaling, or malfunction, the entire cylinder can be extracted for cleaning, repair, or replacement without damaging the partition wall structure, making maintenance extremely convenient. This is particularly suitable for decentralized wastewater treatment scenarios lacking professional maintenance personnel.

[0041] The diameter of the flow manifold 11 is larger than the diameter of the oxygen mixing hole 10.

[0042] The upper and lower rows of nozzles feature differentiated aperture designs, adaptively matched to their respective functional roles. The flow-pushing and confluence holes 11 employ a larger aperture, enabling a larger single-hole air volume and stronger jet flow, ensuring the driving force for bottom flow and lateral confluence. This effectively propels the high-density bottom mud-water mixture and sediment packing, ensuring activation of the bottom flow. Simultaneously, the larger aperture is less prone to clogging by sludge and debris, resulting in stronger operational stability and making it more suitable for harsh conditions close to the bottom of the tank. The oxygenation mixing holes 10 use a smaller aperture, cutting compressed air into finer microbubbles, increasing the specific surface area of ​​gas-liquid contact, significantly improving oxygen transfer efficiency and oxygenation effect. Less air is needed to meet the dissolved oxygen requirements of the aerobic zone 23, further reducing operating energy consumption. The dense arrangement of small apertures also creates a more uniform bubble distribution field, ensuring uniform oxygenation throughout the tank and preventing areas of insufficient dissolved oxygen.

[0043] During overall operation, wastewater, after being treated by the pretreatment unit 1, flows by gravity into the multi-stage biological reaction unit 2. It sequentially passes through the anaerobic zone 21 and the anoxic zone 22 to complete the hydrolysis, acidification, and denitrification processes. Subsequently, it flows evenly into the aerobic zone 23 through the sawtooth overflow trough 6 at the top of the double-cavity partition wall 5. Compressed air is introduced into the aeration chamber 8 and released into the aerobic zone 23 water body through the lower push-flow confluence hole 11 and the upper oxygenation mixing hole 10. This creates a composite flow field of forward push and lateral confluence at the bottom layer, and an oxygenation mixing and vertical circulation flow field in the middle and upper layers. The combined effect of these two processes constructs a three-dimensional, ordered flow field, ensuring effective oxygenation while thoroughly activating the bottom water body, eliminating sludge accumulation and dead zones. The nitrified liquid, which has completed the nitrification reaction in the aerobic zone 23, enters the return cylinder 12 through the tangential inlet 13 under the action of air lift. After passing through the first-stage cyclone separation and the second-stage separation of the baffle plate 17 to remove most of the activated sludge, it is lifted to the upper part of the cylinder by the air lift nozzle 16 and finally flows back to the anoxic zone 22 by gravity through the return outlet 14 to participate in the denitrification process. During the return process, the adaptive throttling structure 18 can automatically adjust the return flow according to the aeration intensity to accurately match different operating loads. The effluent from the aerobic zone 23 continues to flow by gravity through the post-anoxic zone 24 and the terminal aerobic zone 25 to complete the deep treatment before entering the inclined tube sedimentation unit 3 for sludge-water separation. The supernatant is then treated by the deep filtration unit 4 before being discharged in compliance with standards.

[0044] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A low-energy, non-powered backflow, integrated wastewater treatment device, comprising a pretreatment unit (1), a multi-stage step biological reaction unit (2), an inclined tube sedimentation unit (3), and a deep filtration unit (4) connected in sequence, wherein the multi-stage step biological reaction unit (2) is sequentially divided into an anaerobic zone (21), an anoxic zone (22), an aerobic zone (23), a post-anoxic zone (24), and a terminal aerobic zone (25) along the water flow direction, and the bottom elevation of each zone decreases stepwise along the water flow direction, relying on the water level difference to achieve gravity flow, characterized in that: A double-cavity partition wall (5) is provided between the anoxic zone (22) and the aerobic zone (23). A sawtooth overflow groove (6) is provided at the top of the double-cavity partition wall (5). A horizontal partition plate (7) is fixedly provided on the inner side of the double-cavity partition wall (5). The inner side of the double-cavity partition wall (5) is completely separated by the partition plate (7) into a lower aeration chamber (8) and an upper return chamber (9). The aeration chamber (8) has oxygenation mixing holes (10) and flow-generating confluence holes (11) on the upper and lower sides of its sidewall facing the aerobic zone (23). The oxygenation mixing holes (10) and flow-generating confluence holes (11) share the same aeration air source. The return chamber (9) is equipped with multiple return cylinders (12). The lower sidewall of the return cylinder (12) has a tangential inlet (13) facing the aerobic zone (23). The top of the return cylinder (12) extends upward through the top surface of the sawtooth overflow channel (6) and the sidewall has a return outlet (14) facing the anoxic zone (22). The elevation of the return outlet (14) is higher than the normal operating water level of the anoxic zone (22).

2. The low-energy-consumption, non-powered backflow, integrated wastewater treatment device according to claim 1, characterized in that: The axis of the push flow confluence hole (11) is inclined forward at 15°-20° along the water flow direction. The push flow confluence holes (11) are evenly arranged along the width of the pool. The hole directly below each return cylinder (12) is the main push flow hole (111), and the holes between adjacent return cylinders (12) and at the corners of both sides of the pool are side confluence holes (112).

3. The low-energy-consumption, non-powered backflow, integrated wastewater treatment device according to claim 2, characterized in that: The axis of the side confluence hole (112) is horizontally deflected by 15°-20° towards the nearest return cylinder (12) to guide the bottom water to converge directly below the return cylinder (12) while flowing forward. The axis of the main push hole (111) is arranged along the front of the water flow to drive the bottom water to flow forward and flush the sediment at the bottom of the pool.

4. The low-energy-consumption, non-powered backflow, integrated wastewater treatment device according to claim 1, characterized in that: The oxygenation mixing hole (10) is located on the upper side wall of the aeration chamber (8) facing the aerobic zone (23), and the axis of the oxygenation mixing hole (10) is arranged at an angle of 45°-60° upward. The number of holes is greater than that of the flow-pushing confluence hole (11). The position of the oxygenation mixing hole (10) is directly opposite the water drop trajectory of the sawtooth overflow channel (6).

5. The low-energy-consumption, non-powered backflow, integrated wastewater treatment device according to claim 1, characterized in that: The lower inner side of the return cylinder (12) is provided with a spiral guide vane (15), and the tangential water inlet (13) is opened along the tangential direction of the inner wall of the return cylinder (12), and its inner side is smoothly connected to the starting end of the spiral guide vane (15).

6. The low-energy-consumption, non-powered backflow, integrated wastewater treatment device according to claim 5, characterized in that: The return cylinder (12) is equipped with an air lift nozzle (16). The air lift nozzle (16) is located above the spiral guide vane (15). The air lift nozzle (16) is located at the center of the cylinder. The air outlet direction is coaxial with the cylinder axis and perpendicular to the upward direction. The air lift nozzle (16) is connected to the main aeration air source of the aeration chamber (8) through a branch pipe.

7. The low-energy-consumption, non-powered backflow, integrated wastewater treatment device according to claim 6, characterized in that: The reflux cylinder (12) is provided with a plurality of staggered baffles (17), which are located above the air lift nozzle (16) and are arranged at an angle downward inside the reflux cylinder (12).

8. The low-energy-consumption, non-powered backflow, integrated wastewater treatment device according to claim 1, characterized in that: The reflux cylinder (12) is also equipped with an adaptive throttling structure (18), including an annular float (181), a vertical connecting rod (182), an arc-shaped shielding baffle (183), a guide rib (184), and a lower limit block (185). The annular float (181) floats on the gas-liquid mixture surface inside the reflux cylinder (12) and is connected to the arc-shaped shielding baffle (183) through the vertical connecting rod (182). The arc-shaped shielding baffle (183) fits against the inner wall of the cylinder and covers the reflux outlet (14). The guide rib (184) is fixedly set on the inner side wall of the reflux cylinder (12). The annular float (181) has a matching guide slot on its outer side. The lower limit block (185) is fixedly set at the bottom of the guide rib (184) to limit the lowest falling position of the annular float (181) and retain the basic flow gap.

9. The low-energy-consumption, non-powered backflow, integrated wastewater treatment device according to claim 1, characterized in that: The reflux cavity (9) is fixedly provided with mounting blocks (19) on the upper and lower sides. The mounting block (19) has a through hole for embedding the reflux cylinder (12) in the middle. The reflux cylinder (12) is a prefabricated round tube, which is modularly embedded in the reserved through hole of the mounting block (19).

10. The low-energy-consumption, non-powered backflow, integrated wastewater treatment device according to claim 1, characterized in that: The diameter of the flow manifold (11) is larger than the diameter of the oxygen mixing hole (10).

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