Ammonia-nitrogen industrial wastewater treatment system and wastewater treatment method

Abstract

This application discloses an ammonia nitrogen industrial wastewater treatment system, comprising: a sedimentation tank; a mixing tank connected to the sedimentation tank, the mixing tank being equipped with an alkali addition port and a stirrer; a primary treatment unit connected to the mixing tank, used for removing free ammonia from the wastewater by stripping; and a secondary treatment unit connected to the primary treatment unit, used for removing total nitrogen from the wastewater by biological denitrification. This application relates to the field of industrial wastewater treatment technology. This ammonia nitrogen industrial wastewater treatment system and method, through a triple asymmetric distribution of denser spray nozzles at the top and sparser ones at the bottom, sparser spray nozzles at the top and denser ones at the bottom, and fewer nozzles at the bottom and more nozzles at the top of the annular spray pipe, allows the high-concentration zone at the bottom to obtain more gas and the low-concentration zone at the top to obtain more wastewater, thus resolving the contradiction between concentration gradient and uniform supply. The system employs a three-layer concentric spray structure consisting of a central liquid distribution shaft, an outer peripheral gas distribution shaft, and an annular spray pipe, combined with the rotation and lifting of the outer peripheral gas distribution shaft, to achieve three-dimensional interpenetrating contact of gas and liquid, significantly improving the mass transfer coefficient.

Description

Technical Field

[0001] This application relates to the field of industrial wastewater treatment technology, specifically to an ammonia nitrogen industrial wastewater treatment system and wastewater treatment method. Background Technology

[0002] Ammonia nitrogen is one of the main pollutants in industrial wastewater, widely found in the production wastewater of industries such as synthetic ammonia, ammonium nitrate, fertilizer, and coal chemical industry. Typical characteristics of this type of wastewater include high ammonia nitrogen concentration, low carbon-to-nitrogen ratio, and poor biodegradability. If discharged directly without proper treatment, it can lead to eutrophication of receiving water bodies, causing serious harm to the ecological environment.

[0003] Currently, the main treatment method for high-concentration ammonia nitrogen wastewater is stripping, which involves converting ammonium ions in the wastewater into free ammonia under alkaline conditions, and then stripping it from the liquid phase to the gas phase using a carrier gas (air or steam), thus achieving rapid removal of ammonia nitrogen. Based on their structure, stripping towers are mainly divided into two types: packed towers and spray towers.

[0004] Packed towers are constructed by filling the tower with packing material to increase the gas-liquid contact area. Wastewater is sprayed down from the top of the tower, while gas is blown in from the bottom, creating a counter-current gas-liquid contact on the packing surface, thereby improving stripping efficiency. For example, Chinese invention patent CN120518241 A discloses a stripping tower that utilizes a packing layer structure to enhance the gas-liquid contact effect. However, packed towers have significant drawbacks in actual operation: the packing layer is prone to scaling and clogging, especially when treating wastewater with high hardness or high suspended solids. Scale can clog the gaps between the packing layers, leading to uneven airflow distribution, channeling and wall flow phenomena, failure of some packing areas, frequent and costly maintenance and cleaning.

[0005] Given the inherent limitations of packed towers, spray-type stripping towers have gained increasing attention in recent years. Spray towers do not have a packing layer; instead, they rely on atomizing nozzles to spray wastewater into fine droplets that come into contact with the gas, fundamentally avoiding the problem of packing blockage. However, due to the lack of a packing layer's retention effect, ordinary spray towers have a shorter residence time for wastewater droplets within the tower, resulting in insufficient gas-liquid contact and generally lower stripping efficiency compared to packed towers. Therefore, current technological improvements to spray towers mainly focus on extending the gas-liquid contact time and increasing the gas-liquid contact efficiency to enhance the stripping effect. For example, Chinese invention patent CN 117185397 B discloses an ammonia nitrogen stripping device that improves gas-liquid contact efficiency through a multi-stage stripping mechanism, thereby enhancing the stripping effect.

[0006] However, many factors actually affect stripping efficiency, and increasing the gas-liquid contact time and area is only one of them. The inventors believe that improving stripping efficiency is currently limited by at least the following aspects: First, there is a mismatch between the gas-liquid distribution and the concentration gradient. During continuous stripping, the concentration of free ammonia in the wastewater exhibits a natural gradient along the tower height: the concentration is highest at the bottom, gradually decreasing as the wastewater flows downwards, reaching its lowest point at the bottom outlet. Stripping efficiency is directly related to the concentration difference between the gas and liquid phases—the greater the concentration difference, the stronger the mass transfer driving force and the faster the stripping rate. However, existing spray-type stripping towers use fixed water and gas distribution devices, supplying gas and liquid almost uniformly along the tower height, failing to differentiate distribution based on the actual ammonia nitrogen concentration at each height. The objective reason for this is that the design of existing equipment aims for "uniform water and gas distribution," assuming that a more uniform gas-liquid distribution leads to higher stripping efficiency, while ignoring the natural decrease in free ammonia concentration along the tower height during stripping. This results in an inherent technical problem: the high-concentration zone at the bottom cannot fully utilize its mass transfer potential due to insufficient gas supply, becoming a "rate-limiting link" in the stripping process; while the low-concentration zone at the top receives excessive gas supply, leading to energy waste. In other words, there is an inherent structural mismatch between the "uniform supply" mode of existing spray stripping towers and the "concentration gradient" in the stripping process.

[0007] Second, the mass transfer efficiency at the gas-liquid interface is limited. After gas is ejected from the gas distribution holes, it forms bubbles. These bubbles are prone to coalescing during their ascent, leading to a sharp decrease in specific surface area and a reduction in the gas-liquid contact area, thus lowering mass transfer efficiency. Studies have shown that bubble coalescence is a common phenomenon in gas-liquid two-phase flow. After coalescence, the bubble diameter increases, the specific surface area decreases, and the mass transfer resistance increases significantly. Simultaneously, during bubble ascent, a stable liquid boundary layer exists at the gas-liquid interface. Free ammonia needs to diffuse through this layer to enter the gas phase, resulting in significant mass transfer resistance. Existing spray-type stripping towers mainly rely on gravity spraying and airflow entrainment for gas-liquid contact, lacking active means to suppress bubble coalescence and a continuous disturbance mechanism for the liquid boundary layer. Even extending the gas-liquid contact time cannot fundamentally solve these problems.

[0008] Therefore, there is an urgent need for a new type of stripping device that can dynamically match the gas-liquid supply according to the concentration gradient in the tower, while suppressing bubble coalescence and actively destroying the liquid phase boundary layer. Summary of the Invention

[0009] The purpose of this application is to provide an ammonia nitrogen industrial wastewater treatment system and wastewater treatment method, which has the advantages of dynamically controlling the gas-liquid gradient concentration, increasing the gas-liquid contact area and mass transfer coefficient.

[0010] To achieve the above objectives, this application provides the following technical solution: An ammonia nitrogen industrial wastewater treatment system, comprising: Sedimentation tank; A mixing tank is connected to a sedimentation tank, and the mixing tank is equipped with an alkali addition port and a stirrer; The primary treatment unit, connected to the mixing tank, is used to remove free ammonia from the wastewater by stripping. The secondary treatment unit, connected to the primary treatment unit, is used to remove total nitrogen from wastewater through biological denitrification; The primary treatment unit includes: a first container with a horizontal partition inside, dividing the container into an upper driving zone and a lower gas-liquid contact zone; a central liquid distribution shaft rotatably disposed at the axis of the horizontal partition, which is hollow inside and connected to a mixing tank to deliver a portion of wastewater into the gas-liquid contact zone; multiple peripheral gas distribution shafts that are vertically and rotatably disposed in the driving zone and extend to the gas-liquid contact zone, which are hollow inside and connected to a gas source to deliver gas into the gas-liquid contact zone; and multiple annular spray pipes disposed on the inner wall of the gas-liquid contact zone, each annular spray pipe being arranged in layers along the vertical direction and connected to the mixing tank.

[0011] As a further preferred embodiment, the drive zone is provided with a drive mechanism, which includes a drive unit for driving the central liquid distribution shaft to rotate.

[0012] As a further preferred embodiment, the driving mechanism further includes: a first driven gear fixedly disposed on the central liquid distribution shaft and a second driven gear fixedly disposed on each of the outer peripheral air distribution shafts, wherein the second driven gear meshes with the first driven gear and is used to drive each of the outer peripheral air distribution shafts to rotate synchronously when the central liquid distribution shaft rotates; wherein the second driven gear maintains meshing with the first driven gear when the outer peripheral air distribution shafts rise and fall.

[0013] As a further preferred embodiment, the driving mechanism further includes: an external thread disposed on a partial section of the central liquid distribution shaft, an internal gear ring threaded onto the external thread, and a lifting frame fixedly connected to the internal gear ring; the upper ends of each peripheral air distribution shaft are rotatably mounted on the lifting frame via rotary joints, the rotating end of the rotary joint being connected to the peripheral air distribution shaft, and the fixed end of the rotary joint being fixedly connected to the lifting frame; when the central liquid distribution shaft rotates, it drives the internal gear ring to rise and fall via the external thread, thereby driving the lifting frame and the peripheral air distribution shafts to rise and fall synchronously; the other side of the lifting frame is in sliding contact with a linear guide rail disposed on the inner wall of the first container.

[0014] As a further preferred embodiment, the central liquid distribution shaft is provided with multiple sets of spray holes, which are denser at the top and sparser at the bottom along the axial direction; the outer peripheral air distribution shaft is provided with multiple sets of air jet holes, which are sparser at the top and denser at the bottom along the axial direction; the number of nozzles of the annular spray pipe gradually increases from bottom to top, so that the nozzle density of the upper annular spray pipe is greater than that of the lower layer. The central liquid distribution shaft, the outer peripheral air distribution shaft, and the annular spray pipe are arranged in the radial direction from the inside to the outside to form a three-layer concentric spray structure.

[0015] As a further preferred embodiment, the top of the central liquid distribution shaft and each of the outer peripheral gas distribution shafts are respectively provided with a rotary joint, wherein the rotary joint on the central liquid distribution shaft is connected to the water supply pipe of the mixing tank; the rotary joint on each of the outer peripheral gas distribution shafts is connected to the gas source inlet through a hose.

[0016] As a further preferred embodiment, the inner cavity of the central liquid distribution shaft is provided with multiple liquid indexers, and each liquid indexer is arranged in layers along the axial direction to regulate the liquid flow rate at different heights. The liquid separator includes a circular base and a spherical centrifugal contact part disposed at the center of the circular base. An annular water guide groove is provided at the edge of the circular base to allow the liquid to flow to the lower level. The liquid distributor has a higher distribution density in the upper layer than in the lower layer on the central liquid distribution shaft, and the width of the water guide groove of the upper liquid distributor is smaller than that of the lower layer.

[0017] As a further preferred embodiment, the inner cavity of each peripheral air distribution shaft is provided with an integrated annular gas indexer, the gas indexer has an airflow channel in the middle, and multiple guide ports are provided on the side wall of the airflow channel from top to bottom; the outer side of the gas indexer is provided with multiple air chambers, each air chamber is connected to the corresponding jet hole and guide port on the outer side of the peripheral air distribution shaft, and an air filter is installed in the air chamber; The distribution density of the guide ports on the upper layer of the outer peripheral air distribution axis is less than that on the lower layer, and the opening size of the guide ports on the upper layer is smaller than that on the lower layer; multiple sets of labyrinth-shaped baffles are arranged in the airflow channel to slow down the gas flow speed, and the arrangement density of the baffles on the upper layer is less than that on the lower layer, and the length of the baffles on the upper layer is less than that on the lower layer.

[0018] As a further preferred embodiment, a leak-proof sealing assembly is provided between the horizontal partition and the central liquid distribution shaft and each of the outer peripheral gas distribution shafts. The leak-proof sealing assembly includes: a sealing sleeve disposed on the lower side of the horizontal partition, an annular suction pipe embedded in the side of the sealing sleeve, and an air inlet disposed on the side wall of the drive zone; the annular suction pipe is connected to an external suction mechanism and is used to suck up leaked ammonia; the air inlet is used to introduce air into the drive zone so that the air pressure in the drive zone is higher than that in the gas-liquid contact zone.

[0019] The secondary processing unit includes a second container, which has a concentric first and second partition inside, dividing the interior of the container into an aerobic zone, a degassing zone and an anaerobic zone from the outside to the inside.

[0020] The aerobic zone consists of multiple layers of packing material and aeration discs arranged from top to bottom. The packing material layer is multi-layered and covered with ammonia-oxidizing bacteria. The degassing zone is equipped with a degassing assembly, consisting of a motor, stirring shaft, and conveyor belt, used to continuously stir the liquid, allowing air to escape (through the air outlet). An overflow port is located at the top of the first partition, allowing liquid to flow from the aerobic zone into the degassing zone. The anaerobic zone contains multiple layers of packing material covered with anaerobic ammonia-oxidizing bacteria. A nitrogen outlet is located at the top of the anaerobic zone. A solenoid valve is installed on the second partition to control the flow of liquid from the degassing zone into the anaerobic zone. Waste discharge ports are located at the bottom of the aerobic, degassing, and anaerobic zones.

[0021] A method for treating ammonia nitrogen industrial wastewater includes the following steps: S: Precipitation and Alkalinity Adjustment Wastewater is sent to a sedimentation tank for gravity sedimentation to remove suspended solids; the settled wastewater is then sent to a mixing tank, where alkali solution is added and the stirring mechanism is activated to adjust the pH of the wastewater to 10-13. S: Ammonia stripping The wastewater treated by S is sent to the primary treatment unit. The wastewater is divided into two streams: one stream is sprayed into the center of the gas-liquid contact zone through the spray hole of the central liquid distribution shaft, and the other stream is sprayed into the inner wall of the gas-liquid contact zone through the annular spray pipe. At the same time, gas is sprayed into the gas-liquid contact zone through the jet holes of each peripheral gas distribution shaft. Each peripheral gas distribution shaft rotates and moves up and down synchronously while spraying gas, so that the gas and wastewater can fully contact each other according to the gradient requirements, and the free ammonia in the wastewater is blown off and discharged from the free ammonia outlet at the top of the gas-liquid contact zone. S: Biological denitrification The wastewater treated with sulfur dioxide (S) is sent to the bottom of the aerobic zone of the secondary treatment unit. It is aerated by an aeration device and flows upward through the packing layer. Under the action of ammonia-oxidizing bacteria, some ammonia nitrogen is oxidized into nitrite nitrogen. The water treated in the aerobic zone overflows from the top of the first partition into the deaeration zone, where dissolved oxygen is removed by the deaeration structure. The deaerated water enters the anaerobic zone from the bottom of the second partition and flows upward through the packing layer. Under the action of anaerobic ammonia-oxidizing bacteria, the remaining ammonia nitrogen and nitrite nitrogen are converted into nitrogen gas and removed. The treated water is discharged from the effluent outlet at the top of the anaerobic zone.

[0022] In summary, the present invention has at least one of the following beneficial technical effects: 1. This invention employs a triple asymmetrical distribution design: the liquid spray holes on the central liquid distribution shaft are denser at the top and sparser at the bottom along the axial direction; the air jet holes on the outer peripheral air distribution shaft are sparser at the top and denser at the bottom along the axial direction; and the number of nozzles in the annular spray pipe gradually increases from bottom to top. This design ensures that the high-concentration zone at the bottom receives more gas supply, while the low-concentration zone at the top receives more fresh wastewater replenishment. The high-concentration zone at the bottom, equipped with high-density gas, fully utilizes the large concentration difference to achieve rapid stripping; the high-density spray at the top creates countercurrent contact between the wastewater and the rising gas, extending the effective contact time. These three distributions complement and synergistically resolve the contradiction between "concentration gradient and uniform supply" in existing technologies.

[0023] 2. In this invention, the central liquid distribution shaft, the outer peripheral gas distribution shaft, and the annular spray pipe are arranged radially from the inside out, forming a three-layer concentric spray structure—wastewater is simultaneously sprayed from the shaft center and the inner wall towards the center, while gas is sprayed from the middle layer inwards and outwards. These three elements interweave spatially, providing comprehensive coverage. Each outer peripheral gas distribution shaft rotates and moves up and down synchronously while spraying gas. The tangential flow generated by the rotation continuously disrupts the liquid boundary layer at the gas-liquid interface, and the up-and-down motion causes the bubble release height to change continuously, preventing bubbles from rising along a fixed path and generating wakes and coalescing. This structure enables three-dimensional interpenetrating contact between the gas and liquid phases in various gradient ranges. Whether in high-concentration or low-concentration areas, wastewater and air can fully integrate across the entire cross-section, significantly increasing the gas-liquid contact area and mass transfer coefficient.

[0024] 3. The liquid distributor in the inner cavity of the central liquid distribution shaft is layered. Its upper layer has a high distribution density and narrow guide channels, allowing the liquid to linger and spray more frequently, achieving a gradient liquid distribution (more at the top, less at the bottom). The outer peripheral gas distribution shaft features an integrated annular gas distributor. Its upper layer has a low distribution density of guide ports, small opening size, and short, sparse baffles, allowing the gas to achieve a larger flow rate in the lower layer, achieving a gradient gas distribution (more at the bottom, less at the top). This distributor structure ensures precise matching of the gas and liquid supply to the concentration gradient requirements at each height, avoiding local oversupply or undersupply. The leak-proof sealing device uses a dual mechanism of negative pressure suction and positive pressure isolation to prevent ammonia from escaping to the drive area, protecting transmission components from corrosion and extending the equipment's service life. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of this application; Figure 2 This is a cross-sectional view of the primary processing unit structure of this application; Figure 3 This is a cross-sectional view of the secondary processing unit structure of this application; Figure 4 This is a half-sectional schematic diagram of the primary processing unit of this application; Figure 5 This is a half-sectional schematic diagram of the secondary processing unit of this application; Figure 6 This is an enlarged view of the structure at point A in this application; Figure 7 This is a partial sectional view of the central liquid distribution axis of this application; Figure 8 This is a schematic diagram of the liquid indexer structure of this application; Figure 9 This is a schematic diagram of the outer peripheral air distribution shaft structure of this application.

[0026] In the diagram: 1. Sedimentation tank; 2. Mixing tank; 21. Alkali inlet; 22. Stirrer; 3. Primary processing unit; 31. First container; 310. Gas source inlet; 311. Horizontal baffle; 32. Central liquid distribution shaft; 320. Spray nozzle; 321. Liquid distributor; 322. Circular base; 323. Spherical centrifugal contact part; 324. Water guide groove; 33. Outer peripheral gas distribution shaft; 330. Jet nozzle; 331. Gas distributor; 332. Airflow channel; 333. Flow guide port; 334. Gas chamber; 335. Air filter; 336. Baffle; 34. Annular spray pipe; 35. Rotary joint; 36. Hose; 37. Drive mechanism; 371. Drive unit; 372. First driven gear; 373. Second driven gear; 374. Internal gear ring; 375. Lifting frame; 376. Linear guide rail; 38. Shear blade; 39. Free ammonia outlet; 4. Secondary treatment unit; 41. Second container; 411. Aerobic zone; 412. Degassing zone; 413. Anaerobic zone; 42. First partition; 43. Second partition; 44. Packing layer; 45. Aeration disc; 46. Air outlet; 47. Nitrogen outlet; 48. Solenoid valve; 49. Degassing assembly; 40. Sewage outlet; 5. Leak-proof sealing assembly; 51. Sealing sleeve; 52. Annular vent pipe; 53. Air inlet; 6. Water supply pipeline. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0028] like Figure 1 As shown, this application provides a technical solution: an ammonia nitrogen industrial wastewater treatment system, comprising; Sedimentation tank 1 is used to settle the wastewater before treatment, so that large-volume waste is deposited at the bottom of the tank and prevented from being carried into the subsequent treatment system. The mixing tank 2 is connected to the sedimentation tank 1 via a pump and a water supply pipe 6. The mixing tank 2 is equipped with an alkali inlet 21 and a stirrer 22. The alkali solution (such as sodium hydroxide) is added into the mixing tank 2 through the alkali inlet 21 and mixed with the wastewater by the stirrer 22 (the motor and the stirring shaft are matched, and the conventional structure is not described here) to adjust the pH of the wastewater to 10~13. The primary treatment unit 3 is connected to the mixing tank 2 via a pump and a water pipeline 6, and is used to remove free ammonia from the wastewater by stripping. Secondary treatment unit 4 is connected to primary treatment unit 3 via a pump and water pipeline 6, and is used to remove total nitrogen from wastewater through biological denitrification. like Figure 2 As shown in Figure 4, the primary processing unit 3 includes: a first container 31, which has a horizontal partition 311 inside, dividing the container into an upper driving zone and a lower gas-liquid contact zone; the driving zone is provided with a driving mechanism 37, which includes a driving unit 371 for driving the central liquid distribution shaft 32 to rotate. The driving unit 371 is mainly composed of a servo motor and a gearbox. The central liquid distribution shaft 32 is coaxially fixed with one of the gears (not shown in the figure), i.e., a speed reducer.

[0029] A central liquid distribution shaft 32 is rotatably mounted at the center of the horizontal partition. It is hollow inside and connected to the mixing tank 2 to deliver some wastewater into the gas-liquid contact zone. Multiple peripheral gas distribution shafts 33 are vertically and rotatably mounted in the drive zone and extend to the gas-liquid contact zone. They are hollow inside and connected to the gas source to deliver gas (gas temperature is 60-80 degrees Celsius) into the gas-liquid contact zone.

[0030] The drive mechanism 37 further includes: a first driven gear 372 fixedly mounted on the central liquid distribution shaft 32, and a second driven gear 373 fixedly mounted on each of the outer peripheral air distribution shafts 33. The second driven gear 373 meshes with the first driven gear 372 and is used to drive each of the outer peripheral air distribution shafts 33 to rotate synchronously when the central liquid distribution shaft 32 rotates. The second driven gear 373 maintains meshing with the first driven gear 372 when it rises and falls with the outer peripheral air distribution shafts 33.

[0031] The drive mechanism 37 further includes: an external thread (bidirectional thread, capable of automatic lifting) disposed on a partial section of the central liquid distribution shaft 32, an internal gear ring 374 threaded onto the external thread, and a lifting frame 375 fixedly connected to the internal gear ring 374; the upper ends of each peripheral air distribution shaft 33 are rotatably mounted on the lifting frame 375 via a rotary joint 35, the rotating end of the rotary joint 35 being connected to the peripheral air distribution shaft 33, and the fixed end of the rotary joint 35 being fixedly connected to the lifting frame 375; when the central liquid distribution shaft 32 rotates, it drives the internal gear ring 374 to rise and fall through the external thread, thereby driving the lifting frame 375 and the peripheral air distribution shaft 33 to rise and fall synchronously; the other side of the lifting frame 375 is in sliding contact with a linear guide rail 376 disposed on the inner wall of the first container 31.

[0032] And multiple annular spray pipes 34 are set on the inner wall of the gas-liquid contact zone. Each annular spray pipe 34 is arranged in layers along the vertical direction and connected to the mixing tank 2. The number of nozzles of the annular spray pipe 34 gradually increases from bottom to top, so that the nozzle density of the upper annular spray pipe 34 is greater than that of the lower layer. In addition, the spacing of the annular spray pipes 34 decreases from top to bottom. The purpose of this design is to increase the spray density of the upper annular spray pipe 34 and play the role of gradient regulation of liquid distribution.

[0033] Rotary joints 35 are provided on the top of the central liquid distribution shaft 32 and each of the outer peripheral gas distribution shafts 33. The rotary joints 35 on the central liquid distribution shaft 32 are connected to the water supply pipe 6 of the mixing tank 2. The rotary joints 35 on each of the outer peripheral gas distribution shafts 33 are connected to the gas source inlet 310 through the hose 36.

[0034] In summary, such as Figure 1-2 As shown, the waste liquid after pH adjustment enters the gas-liquid contact zone through two channels, namely the annular spray pipe 34 and the central liquid distribution shaft 32. The flow rate into the relevant channels can be controlled by the regulating valve (not shown in the figure) to achieve uniform liquid distribution.

[0035] The first embodiment regarding the central liquid distribution shaft Multiple sets of spray holes 320 are arranged on the central liquid distribution shaft 32. The spray holes 320 are densely distributed at the top and sparsely distributed at the bottom along the axial direction. This design is also based on the concept of gradient control of liquid distribution. The central liquid distribution shaft 32, the outer peripheral air distribution shaft 33 and the annular spray pipe 34 are arranged in the radial direction from the inside to the outside to form a three-layer concentric spray structure.

[0036] The second embodiment regarding the central liquid distribution shaft like Figure 7-8 As shown, the inner cavity of the central liquid distribution shaft 32 is provided with multiple liquid indexers 321, and each liquid indexer 321 is arranged in layers along the axial direction to regulate the liquid flow rate at different heights. The liquid distributor 321 includes a circular base 322 and a spherical centrifugal contact part 323 disposed at the center of the circular base 322 (which helps to evenly disperse and throw the waste liquid to the surroundings and evenly flow down through the water guide groove 324). The circular base 322 has an annular water guide groove 324 at its edge for the liquid to flow to the lower level. The liquid distributor 321 has a higher distribution density in the upper layer than in the lower layer of the central liquid distribution shaft 32, and the width of the water guide groove 324 of the upper liquid distributor 321 is smaller than that of the lower layer.

[0037] To further enhance the gradient adjustment of liquid distribution, multiple liquid distributors 321 are installed on the inner wall of the central liquid distribution shaft 32 to automatically regulate the distribution of waste liquid within the shaft. Specifically, in the upper section of the central liquid distribution shaft 32, the density of liquid distributors 321 is higher, and the opening size of the water guide trough 324 is smaller. The purpose is to extend the flow time of waste liquid in this section, thereby allowing more waste liquid to be sprayed out through this section.

[0038] The first embodiment of the peripheral air distribution shaft The outer peripheral air distribution shaft 33 is provided with multiple sets of air jet holes 330, which are distributed sparsely at the top and densely at the bottom along the axial direction.

[0039] The gradient setting of the jet orifice 330 achieves the purpose of gradient control of air distribution.

[0040] The second embodiment regarding the outer peripheral air distribution shaft like Figure 9 As shown, each outer peripheral air distribution shaft 33 has an integrated annular gas distributor 331 in its inner cavity. The gas distributor 331 has an airflow channel 332 in its middle. Multiple guide ports 333 are provided on the side wall of the airflow channel 332 from top to bottom. The outer side of the gas distributor 331 has multiple air chambers 334. Each air chamber 334 is connected to the corresponding jet hole 330 and guide port 333 on the outer side of the outer peripheral air distribution shaft 33. An air filter 335 is installed in the air chamber 334. The distribution density of the guide port 333 on the upper layer of the outer peripheral air distribution shaft 33 is less than that on the lower layer, and the opening size of the upper guide port 333 is smaller than that on the lower layer; multiple sets of labyrinth-shaped baffles 336 are arranged in the airflow channel 332. The baffles 336 are fan-shaped in the horizontal radial direction to slow down the gas flow speed. The arrangement density of the baffles 336 is less in the upper layer than in the lower layer, and the length of the baffles 336 is less in the upper layer than in the lower layer.

[0041] To further enhance the gradient adjustment of air distribution, gas distributors 331 are arranged inside each peripheral air distribution shaft 33. Hot air enters through the air source inlet 310 and enters the interior of the peripheral air distribution shaft 33 along the hose 36. Inside the shaft, the hot air first enters the airflow channel 332, then passes through the guide port 333 and enters the air chamber 334. After filtration, it is ejected from the jet port 330. By differentiating the guide ports 333 and setting baffles 336, the air stays in the upper zone for a shorter time and the jet volume is less, allowing more air to be discharged from the bottom of the peripheral air distribution shaft 33.

[0042] A leak-proof sealing assembly 5 is provided between the horizontal partition 311 and the central liquid distribution shaft 32 and each of the outer peripheral gas distribution shafts 33. The leak-proof sealing assembly 5 includes: a sealing sleeve 51 disposed on the lower side of the horizontal partition, an annular suction pipe 52 embedded in the side of the sealing sleeve 51, and an air inlet 53 disposed on the side wall of the drive zone. The annular suction pipe 52 is connected to an external suction mechanism and is used to suck up leaked ammonia. The air inlet 53 is used to introduce air into the drive zone so that the air pressure in the drive zone is higher than that in the gas-liquid contact zone.

[0043] Shear blades 38 can be arranged on both the central liquid distribution shaft 32 and the outer peripheral gas distribution shaft 33.

[0044] Wastewater and air come into full contact in the gas-liquid contact zone to achieve aeration. Ammonia escapes from the liquid and is discharged through the free ammonia outlet 39. In order to reduce the escape of ammonia from the gaps between the horizontal baffle 311 and the central liquid distribution shaft 32 and each outer peripheral air distribution shaft 33, and to prevent ammonia from entering the drive zone and causing corrosion to the drive components, a double leak-proof structure is set up.

[0045] Firstly, when the system is working, air at a certain pressure is pumped into the drive zone through the air inlet 53, so that the air pressure in the drive zone is slightly greater than the air pressure in the gas-liquid contact zone, thereby achieving the purpose of gas sealing. Under the action of pressure difference, ammonia gas is difficult to escape into the drive zone. Secondly, a sealing sleeve 51 and an annular extraction pipe 52 are installed below the horizontal partition 311 to extract ammonia gas that has escaped to this location.

[0046] like Figure 3 As shown in Figure 5, the secondary processing unit 4 includes a second container 41, which has a concentric first partition 42 and a second partition 43 inside, dividing the interior of the container into an aerobic zone 411, a degassing zone 412 and an anaerobic zone 413 from the outside to the inside.

[0047] The aerobic zone 411 contains a packing layer 44 and an aeration disc 45 arranged from top to bottom. The packing layer 44 is multi-layered and covered with ammonia-oxidizing bacteria. The degassing zone 412 is equipped with a degassing assembly 49, which consists of a motor, a stirring shaft, and a conveyor belt. This assembly continuously stirs the liquid to allow air to escape (from the air outlet 46). An overflow port is provided at the upper end of the first partition 42, allowing liquid to flow from the aerobic zone 411 into the degassing zone 412. The anaerobic zone 413 contains a multi-layered packing layer 44 covered with anaerobic ammonia-oxidizing bacteria. A nitrogen outlet 47 is provided at the top of the anaerobic zone 413. A solenoid valve 48 is installed on the second partition 43 to control the flow of liquid from the degassing zone 412 into the anaerobic zone 413. Waste outlets 40 are provided at the bottom of the aerobic zone 411, the degassing zone 412, and the anaerobic zone 413.

[0048] The aerobic zone 411 and the anaerobic zone 413 are relatively isolated by the degassing zone 412. Therefore, the aerobic reaction in the aerobic zone 411 (oxidizing part of the ammonia nitrogen to nitrite nitrogen under the action of ammonia oxidizing bacteria) and the anaerobic reaction in the anaerobic zone 413 (converting the remaining ammonia nitrogen and nitrite nitrogen into nitrogen gas under the action of anaerobic ammonia oxidizing bacteria) do not interfere with each other. The size-to-width ratio of the aerobic zone 411, the degassing zone 412 and the anaerobic zone 413 is preferably 1:2:4.

[0049] A method for treating ammonia nitrogen industrial wastewater includes the following steps: S1: Precipitation and Alkali Adjustment Wastewater is sent to sedimentation tank 1 for gravity sedimentation to remove suspended solids; after sedimentation, the wastewater is sent to mixing tank 2, alkali solution is added and the stirring mechanism is started to adjust the pH of the wastewater to 10~13. S2: Ammonia stripping The wastewater treated by S1 is sent to the primary treatment unit 3. The wastewater is divided into two paths: one path is sprayed into the center of the gas-liquid contact zone through the spray hole 320 of the central liquid distribution shaft 32, and the other path is sprayed into the inner wall of the gas-liquid contact zone through the annular spray pipe 34. At the same time, gas is sprayed into the gas-liquid contact zone through the jet holes 330 of each peripheral gas distribution shaft 33. Each peripheral gas distribution shaft 33 rotates and moves up and down synchronously while spraying gas, so that the gas and wastewater can fully contact each other according to the gradient requirements, and the free ammonia in the wastewater is blown off and discharged from the free ammonia outlet 39 at the top of the gas-liquid contact zone. S3: Biological denitrification The wastewater treated by S2 is sent to the bottom of the aerobic zone 411 of the secondary treatment unit 4. It is aerated by an aeration device and flows upward through the packing layer 44. Under the action of ammonia oxidizing bacteria, some ammonia nitrogen is oxidized into nitrite nitrogen. The water treated in the aerobic zone 411 overflows from the top of the first partition 42 into the degassing zone 412, where dissolved oxygen is removed by the degassing structure. The degassed water enters the anaerobic zone 413 from the bottom of the second partition 43 and flows upward through the packing layer 44. Under the action of anaerobic ammonia oxidizing bacteria, the remaining ammonia nitrogen and nitrite nitrogen are converted into nitrogen gas and removed. The treated water is discharged from the outlet at the top of the anaerobic zone 413.

[0050] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0051] In operation, wastewater is first treated in sedimentation tank 1 to remove suspended solids, then fed into mixing tank 2. Alkali solution is added (through alkali inlet 21) to adjust the pH to 10-13, converting ammonium ions in the wastewater into free ammonia. The adjusted wastewater is then fed into primary treatment unit 3 via two streams: one stream is sprayed into the center of the gas-liquid contact zone through the spray hole 320 of the central liquid distribution shaft 32, and the other stream is sprayed into the inner wall of the gas-liquid contact zone through the annular spray pipe 34. Simultaneously, an external air source supplies gas to each peripheral air distribution shaft 33 through rotary joint 35 and hose 36, and the gas is sprayed into the gas-liquid contact zone through jet nozzles 330. Each peripheral air distribution shaft 33 is driven by a drive mechanism 37, performing synchronous rotation and synchronous lifting movements while the gas is being sprayed.

[0052] The spray holes 320 on the central liquid distribution shaft 32 are densely distributed at the top and sparsely distributed at the bottom, with fewer holes at the bottom and more at the top. This, combined with the gradually increasing number of nozzles on the annular spray pipe 34 from bottom to top, ensures that the upper part of the gas-liquid contact zone receives more fresh wastewater replenishment, while the lower part receives a concentrated gas supply. The jet holes 330 on the outer peripheral air distribution shaft 33 are sparsely distributed at the top and densely distributed at the bottom, ensuring that the bottom of the gas-liquid contact zone receives the maximum gas flow rate. This utilizes the greater mass transfer driving force of the high-concentration zone at the bottom to achieve rapid stripping. The liquid distributor 321 regulates the liquid flow rate at each height through the annular water guide groove 324 on the edge of its circular base 322. The upper layer has a high distribution density and the water guide groove 324 is narrow, so that the liquid stays and sprays out more in the upper layer, achieving a gradient liquid distribution of "more at the top and less at the bottom". The gas distributor 331 regulates the gas flow rate through the guide port 333 and the labyrinth-shaped baffle 336 on the side wall of its airflow channel 332. The lower layer has a high distribution density of guide ports 333, a large opening size, and long and dense baffles 336, so that the lower layer can obtain more gas, achieving a gradient gas distribution of "more at the bottom and less at the top".

[0053] The central liquid distribution shaft 32, the outer peripheral gas distribution shaft 33, and the annular spray pipe 34 are arranged radially from the inside out, forming a three-layer concentric spray structure—wastewater is sprayed from the shaft center and inner wall simultaneously towards the center, while gas is sprayed from the middle layer inwards and outwards, with the three layers interpenetrating and fully covering each other in space. This structure enables three-dimensional interpenetrating contact between the gas and liquid phases in various gradient ranges, ensuring that the waste liquid and air can fully mix across the entire cross-section, regardless of whether the concentration is high or low. The rotation of the outer peripheral gas distribution shaft 33 causes the ejected gas to rise in a spiral trajectory in the horizontal plane, preventing bubbles from coalescing along a fixed path; the rise and fall of the outer peripheral gas distribution shaft 33 dynamically changes the bubble release height, prolonging the residence time of bubbles in the liquid phase and further dispersing the distribution of bubbles in the vertical direction. The shear blades 38 provided on the outer wall of the shaft (the shear surface between the shear blades 38 and the liquid can also be provided with jet holes 330 or liquid spray holes 320) continuously generate a shearing effect on the liquid boundary layer, reducing mass transfer resistance. The wastewater after stripping is discharged from the free ammonia outlet 39.

[0054] After stripping, the wastewater is sent to the secondary treatment unit 4. The wastewater enters from the bottom of the aerobic zone 411, flows upward through the aeration disc 45 and the first packing layer (packing layer 44), where some ammonia nitrogen is oxidized to nitrite nitrogen by ammonia-oxidizing bacteria. The treated water overflows from the top of the first partition 42 into the degassing zone 412, where dissolved oxygen is removed by the degassing component 49. The degassed water enters the anaerobic zone 413 from the bottom of the second partition 43, flows upward through the second packing layer (packing layer 44), where the remaining ammonia nitrogen and nitrite nitrogen are converted into nitrogen gas and removed by anaerobic ammonia-oxidizing bacteria. The treated water is discharged from the drain outlet 40 at the bottom of the anaerobic zone 413.

[0055] In summary, this ammonia nitrogen industrial wastewater treatment system and method, through a triple asymmetric distribution of denser spray nozzles at the top and sparser ones at the bottom, sparser spray nozzles at the top and denser ones at the bottom, and fewer nozzles at the bottom and more nozzles at the top of the annular spray pipe, ensures that the high-concentration zone at the bottom receives more gas and the low-concentration zone at the top receives more wastewater, thus resolving the contradiction between concentration gradient and uniform supply. The system employs a three-layer concentric spray structure consisting of a central liquid distribution shaft, an outer peripheral gas distribution shaft, and an annular spray pipe, which, combined with the rotation and lifting of the outer peripheral gas distribution shaft, achieves three-dimensional gas-liquid interpenetrating contact, significantly improving the mass transfer coefficient. The liquid and gas distributors precisely match the gas-liquid requirements at each height, and the leak-proof sealing device prevents ammonia gas escape, extending equipment life.

[0056] It should be noted that all electrical components mentioned in this article are electrically connected to an external main controller and 220V or 380V AC mains power. The main controller can be a conventional, known device such as a computer, and its control principles, internal structure, and control switching methods are all conventional methods of existing technology. These are directly cited here without further elaboration. In this document, relational terms such as "first" and "second" are used merely 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 a process, method, article, or apparatus.

[0057] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An ammonia-nitrogen industrial wastewater treatment system, characterized by, include: Sedimentation tank (1); The mixing tank (2) is connected to the sedimentation tank (1), and the mixing tank (2) is equipped with an alkali addition port (21) and a stirrer (22). The primary treatment unit (3) is connected to the mixing tank (2) and is used to remove free ammonia from the wastewater by stripping. The secondary treatment unit (4) is connected to the primary treatment unit (3) and is used to remove total nitrogen from wastewater through biological denitrification; The primary processing unit (3) includes: a first container (31) with a horizontal partition (311) inside, which divides the container into a driving zone at the top and a gas-liquid contact zone at the bottom; a central liquid distribution shaft (32) rotatably disposed at the axis of the horizontal partition, which is hollow inside and connected to the mixing tank (2) to deliver some wastewater into the gas-liquid contact zone; multiple peripheral gas distribution shafts (33) which are vertically and rotatably disposed in the driving zone and extend to the gas-liquid contact zone, which are hollow inside and connected to a gas source to deliver gas into the gas-liquid contact zone; and multiple annular spray pipes (34) disposed on the inner wall of the gas-liquid contact zone, each annular spray pipe (34) being arranged in layers along the vertical direction and connected to the mixing tank (2); The secondary processing unit (4) includes a second container (41), which has a concentric first partition (42) and second partition (43) inside, dividing the inside of the container into an aerobic zone (411), a degassing zone (412) and an anaerobic zone (413) from the outside to the inside.

2. The ammonia-nitrogen industrial wastewater treatment system according to claim 1, characterized in that: The central liquid distribution shaft (32) is provided with multiple sets of spray holes (320), which are densely distributed at the top and sparsely distributed at the bottom along the axial direction; the outer peripheral air distribution shaft (33) is provided with multiple sets of air jet holes (330), which are sparsely distributed at the top and densely distributed at the bottom along the axial direction; the number of nozzles of the annular spray pipe (34) gradually increases from bottom to top, so that the nozzle density of the upper annular spray pipe (34) is greater than that of the lower layer. The central liquid distribution shaft (32), the outer peripheral air distribution shaft (33) and the annular spray pipe (34) are arranged in the radial direction from the inside to the outside to form a three-layer concentric spray structure.

3. The ammonia-nitrogen industrial wastewater treatment system according to claim 1, characterized in that: The top of the central liquid distribution shaft (32) and each of the outer peripheral gas distribution shafts (33) are respectively provided with a rotary joint (35). The rotary joint (35) on the central liquid distribution shaft (32) is connected to the water supply pipe (6) of the mixing tank (2). The rotary joint (35) on each of the outer peripheral gas distribution shafts (33) is connected to the gas source inlet (310) through a hose (36).

4. The ammonia-nitrogen industrial wastewater treatment system according to claim 1, characterized in that: The inner cavity of the central liquid distribution shaft (32) is provided with multiple liquid indexers (321), and each liquid indexer (321) is arranged in layers along the axial direction to regulate the liquid flow rate at different heights; The liquid distributor (321) includes a circular base (322) and a spherical centrifugal contact part (323) disposed at the center of the circular base (322). An annular water guide groove (324) is provided at the edge of the circular base (322) to allow the liquid to flow to the lower level. The liquid distributor (321) has a higher distribution density in the upper layer than in the lower layer of the central liquid distribution shaft (32), and the width of the water guide groove (324) of the upper liquid distributor (321) is smaller than that of the lower layer.

5. The ammonia-nitrogen industrial wastewater treatment system according to claim 2, characterized in that: Each peripheral air distribution shaft (33) has an integrated annular gas indexer (331) in its inner cavity. The gas indexer (331) has an airflow channel (332) in the middle. Multiple guide ports (333) are provided on the side wall of the airflow channel (332) from top to bottom. The gas indexer (331) has multiple air chambers (334) on its outer side. Each air chamber (334) is connected to the jet hole (330) and guide port (333) on the outer side of the peripheral air distribution shaft (33). An air filter (335) is installed in the air chamber (334). The distribution density of the guide port (333) on the upper layer of the outer peripheral air distribution shaft (33) is less than that on the lower layer, and the opening size of the upper guide port (333) is smaller than that on the lower layer; multiple sets of labyrinth-type baffles (336) are arranged in the airflow channel (332) to slow down the gas flow speed. The arrangement density of the baffles (336) is less in the upper layer than in the lower layer, and the length of the baffles (336) is less in the upper layer than in the lower layer.

6. The ammonia-nitrogen industrial wastewater treatment system according to claim 3, characterized in that: The drive area is provided with a drive mechanism (37), which includes a drive unit (371) for driving the rotation of the central liquid distribution shaft (32).

7. The ammonia-nitrogen industrial wastewater treatment system according to claim 6, characterized in that: The drive mechanism (37) further includes: a first driven gear (372) fixedly mounted on the central liquid distribution shaft (32) and a second driven gear (373) fixedly mounted on each of the outer peripheral air distribution shafts (33). The second driven gear (373) meshes with the first driven gear (372) and is used to drive each of the outer peripheral air distribution shafts (33) to rotate synchronously when the central liquid distribution shaft (32) rotates. The second driven gear (373) maintains meshing with the first driven gear (372) when the outer peripheral air distribution shaft (33) rises and falls.

8. The ammonia-nitrogen industrial wastewater treatment system according to claim 7, characterized in that: The drive mechanism (37) further includes: an external thread set on a partial shaft section of the central liquid distribution shaft (32), an internal gear ring (374) threaded on the external thread, and a lifting frame (375) fixedly connected to the internal gear ring (374); the upper end of each peripheral air distribution shaft (33) is rotatably mounted on the lifting frame (375) through a rotary joint (35), the rotating end of the rotary joint (35) is connected to the peripheral air distribution shaft (33), and the fixed end of the rotary joint (35) is fixedly connected to the lifting frame (375); when the central liquid distribution shaft (32) rotates, it drives the internal gear ring (374) to rise and fall through the external thread, thereby driving the lifting frame (375) and the peripheral air distribution shaft (33) to rise and fall synchronously; the other side of the lifting frame (375) slides in contact with the linear guide rail (376) set on the inner wall of the first container (31).

9. The ammonia-nitrogen industrial wastewater treatment system according to claim 1, characterized in that: Leakage-proof sealing assembly (5) is provided between the horizontal partition (311) and the central liquid distribution shaft (32) and each peripheral gas distribution shaft (33). The leakage-proof sealing assembly (5) includes: a sealing sleeve (51) disposed on the lower side of the horizontal partition, an annular suction pipe (52) embedded in the side of the sealing sleeve (51), and an air inlet (53) disposed on the side wall of the drive area. The annular suction pipe (52) is connected to an external suction mechanism and is used to suck up leaked ammonia. The air inlet (53) is used to introduce air into the drive area so that the air pressure in the drive area is higher than that in the gas-liquid contact area.

10. The wastewater treatment method according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1: Precipitation and Alkali Adjustment Wastewater is sent to sedimentation tank (1) for gravity sedimentation to remove suspended solids; after sedimentation, wastewater is sent to mixing tank (2), alkali solution is added and stirring mechanism is started to adjust the pH of wastewater to 10~13. S2: Ammonia stripping The wastewater treated by S1 is sent to the primary treatment unit (3). The wastewater is divided into two paths: one path is sprayed into the center of the gas-liquid contact zone through the spray hole (320) of the central liquid distribution shaft (32), and the other path is sprayed into the inner wall of the gas-liquid contact zone through the annular spray pipe (34). At the same time, gas is sprayed into the gas-liquid contact zone through the jet holes (330) of each peripheral gas distribution shaft (33). Each peripheral gas distribution shaft (33) rotates and moves up and down synchronously while jetting, so that the gas and wastewater can fully contact according to the gradient requirements, and the free ammonia in the wastewater is blown off and discharged from the free ammonia outlet (39) at the top of the gas-liquid contact zone. S3: Biological denitrification The wastewater treated by S2 is sent to the bottom of the aerobic zone (411) of the secondary treatment unit (4). It is aerated by an aeration device and flows upward through the packing layer (44). Under the action of ammonia oxidizing bacteria, some ammonia nitrogen is oxidized into nitrite nitrogen. The water treated in the aerobic zone (411) overflows from the top of the first partition (42) into the degassing zone (412). The dissolved oxygen in the water is removed by the degassing structure. The degassed water enters the anaerobic zone (413) from the bottom of the second partition (43) and flows upward through the packing layer (44). Under the action of anaerobic ammonia oxidizing bacteria, the remaining ammonia nitrogen and nitrite nitrogen are converted into nitrogen gas and removed. The treated water is discharged from the outlet at the top of the anaerobic zone (413).

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