A system for improving the efficiency of membrane concentrate in treating wastewater by denitrification

Abstract

The present invention provides a system for improving the efficiency of denitrification treatment of sewage membrane concentrated liquid. The system includes a denitrification device, which receives upstream liquid to be treated from the source of membrane concentrated liquid, and denitrifies the upstream liquid to be treated in its body to form denitrified liquid; and a particle suspension device, which suspends endogenous particles in the denitrified liquid in the body of the denitrification device to improve the denitrification efficiency. In addition, the system may also include a cyclone device, a particle shaping orifice plate, and a sedimentation bin to further improve the efficiency of denitrification treatment.

Description

Technical Field

[0001] The invention relates to the field of sewage treatment, and in particular to a system for treating sewage membrane concentrate by denitrification. Background Art

[0002] In recent years, with the rapid development of industrial production, membrane separation technology has been widely used as an efficient, energy-saving and environmentally friendly material separation technology. Membrane separation technology plays an important role in water treatment, food processing, pharmaceutical and other fields, but it also brings new environmental problems. The membrane concentrate produced in the membrane separation process often contains high concentrations of salts, organic matter, heavy metals and other substances, which are difficult to discharge directly and cause serious pollution to the environment. For example, the concentrate produced in the seawater desalination process contains a large amount of salt. Direct discharge will cause the salinity of seawater to increase and affect the marine ecological environment. Summary of the invention

[0003] The present invention provides a system for treating sewage membrane concentrate by denitrification, which comprises

[0004] A denitrification device receives an upstream liquid to be treated whose source is a membrane concentrated liquid, and denitrifies the upstream liquid to be treated in its body to form a denitrified liquid;

[0005] The particle suspension device suspends endogenous particles in the denitrification liquid in the denitrification device body to improve the denitrification efficiency.

[0006] In one embodiment, the system further comprises

[0007] An overflow tank is located at the upper part of the denitrification device, and the body of the denitrification device is connected to the overflow tank through a first orifice plate, and the overflow liquid generated by the overflow of the denitrification liquid enters the overflow tank;

[0008] A cyclone device, which is connected to the overflow tank through a first pipe, and the overflow liquid enters the cyclone device and then swirls to obtain a cyclone liquid;

[0009] a water distributor, which is in communication with the cyclone device and allows the cyclone liquid to enter therein;

[0010] A flow guide device, which is in communication with the water distributor, allowing the cyclone liquid to enter therein to obtain the flow guide liquid, wherein a hole is arranged on the bottom plate of the flow guide device;

[0011] A second pipeline is used to connect the denitrification device and the diversion device so that part of the diversion fluid flows back into the body of the denitrification device;

[0012] The sedimentation bin is connected with the diversion device through the bottom plate of the diversion device, so that part of the diversion liquid falls into the sedimentation bin to form a sedimentation liquid containing plastic particles, and the sedimentation liquid is refluxed into the denitrification device.

[0013] In a specific embodiment, the overflow trough further includes a water outlet, wherein a second orifice plate is arranged at the water outlet of the overflow trough, and the equivalent diameter of the pores of the second orifice plate is 0.05 to 0.2 mm.

[0014] In a specific embodiment, the deposition bin is divided into N layers, N is an integer greater than or equal to 2, each layer is separated by a orifice plate, and the equivalent diameter of the first layer of orifice plate channels from top to bottom is smaller than the equivalent diameter of the bottom plate channels of the guide device, and the equivalent diameter of the lower layer of orifice plate channels between two adjacent layers of orifice plates is smaller than the equivalent diameter of the upper layer of orifice plate channels; the deposition liquid in the deposition bin enters the adjacent lower layer through the orifice plates between the layers, and the deposition liquid in each layer is referred to as the first deposition liquid, the second deposition liquid, and so on from top to bottom.

[0015] In a specific embodiment, when the sedimentation bin is divided into two layers, part of the first sedimentation liquid flows back to the denitrification device, and part of the first sedimentation liquid falls into the lower sedimentation bin to form a second sedimentation liquid, which merges with the overflow liquid and enters the cyclone device together.

[0016] In a specific embodiment, when the sedimentation bin is divided into three layers, part of the first sedimentation liquid flows back to the denitrification device, and part of the first sedimentation liquid falls into the middle sedimentation bin to form a second sedimentation liquid; part of the second sedimentation liquid flows back to the denitrification device, and part of the second sedimentation liquid falls into the lower sedimentation bin to form a third sedimentation liquid, and the third sedimentation liquid merges with the overflow liquid and enters the cyclone device together.

[0017] In a specific embodiment, the channel of the bottom plate of the flow guiding device is a first shaped channel, and the shape of the first shaped channel is at least two of lightning, star, triangle, rhombus, ellipse, irregular circle, crescent, gear, sleeve circle and arc plate, and the equivalent diameter of the first shaped channel has at least two specifications. That is, the first shaped channel is an irregular channel with different diameters.

[0018] In a specific embodiment, the equivalent diameter of the pores of the first orifice plate is 1.5 to 2 mm, so that the overflow liquid does not contain endogenous particles with an equivalent diameter of more than 1.5 to 2 mm; the equivalent diameter of the pores of the bottom plate of the guide device is 1.5 to 2 mm.

[0019] In a specific embodiment, the hole of the orifice plate in the deposition chamber is a second shaped hole, and the shape of the second shaped hole is at least two of lightning, star, triangle, rhombus, ellipse, irregular circle, crescent, gear, sleeve circle and arc plate; and the equivalent diameter of the second shaped hole has at least two specifications. That is, the second shaped hole is an irregularly shaped hole with different diameters.

[0020] In a specific embodiment, the equivalent diameter of the holes of the first layer of the orifice plate of the deposition chamber is 1 to 1.5 mm, and the equivalent diameter of the holes of the bottom layer of the orifice plate of the deposition chamber is 0.2 to 0.5 mm.

[0021] In a specific embodiment, the angle between the flow guiding device and the horizontal plane is 15 to 60°.

[0022] In a specific embodiment, the particle suspension device can be specifically an internal circulation pump or a stirring rod.

[0023] In a specific embodiment, the endogenous particles with a size of 2 to 3 mm in the denitrification device body account for more than 40 wt % of the total endogenous particles.

[0024] In a specific embodiment, the endogenous particles with a diameter of 2 to 3 mm in the denitrification device body account for 40 wt % to 90 wt % of the total endogenous particles.

[0025] In a specific embodiment, endogenous particles with a size of 2 to 3 mm in the body of the denitrification device account for more than 90 wt % of the total endogenous particles.

[0026] The sewage membrane concentrated liquid of the present invention can be a membrane concentrated liquid obtained by single-stage membrane concentration of sewage, or a membrane concentrated liquid obtained by multi-stage membrane concentration of sewage.

[0027] The endogenous particles in the present invention refer to the particles contained in the membrane concentrate or the particles newly generated in the denitrification process, which are relative to the externally added particles.

[0028] Beneficial effects of the present invention: The present invention finds that suspending endogenous particles in the denitrification liquid can achieve the purpose of improving the denitrification efficiency, which not only alleviates the problem of particles settling and adhering to the reaction system, blocking the pipeline, and affecting the denitrification operation, but also can omit the step of adding microbial condensation nuclei. More importantly, suspending endogenous particles as microbial condensation nuclei can produce better denitrification efficiency than existing conventional microbial condensation nuclei (such as zinc oxide). Furthermore, by using a cyclone device and a shaping channel for particles to shape the particles, the denitrification efficiency can be further improved and the denitrification process can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The circulation system of the denitrification tank and the cyclone tank is shown.

[0030] Figure 2 A schematic diagram of an orifice plate showing irregular shaped and varying diameter holes.

[0031] Figure 3 Another schematic diagram of an orifice plate showing special-shaped and different-diameter holes. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with examples, but the examples of the present invention are only exemplary descriptions, and the implementation methods do not constitute limitations of the present invention under any circumstances.

[0033] The membrane concentrate produced by membrane separation can be reduced to nitrogen gas through nitrification and denitrification reactions in turn, including ammonia nitrogen (such as ammonium sulfate and ammonium chloride), nitrite nitrogen (such as sodium nitrite, calcium or magnesium nitrites), and nitrate nitrogen (such as sodium nitrate, calcium or magnesium nitrates), thereby achieving the purpose of nitrogen removal.

[0034] When the nitrification reaction is carried out, it can be completed in the nitrification tank. After the membrane concentrated liquid enters the nitrification tank, microbial agents mainly composed of nitrifying bacteria can be added to carry out partial nitrification reaction to form nitrified liquid. The nitrified nitrified liquid mainly contains ammonium salts, nitrites and nitrates.

[0035] When the denitrification reaction is carried out, it can be completed in the denitrification tank. After the membrane concentrate and / or nitrified liquid enters the denitrification tank, denitrifying microbial agents can be added to carry out the denitrification reaction to complete the denitrification process of the membrane concentrate. The denitrified liquid obtained after the treatment can be directly discharged or enter other units for subsequent treatment.

[0036] Denitrification reaction can be divided into autotrophic denitrification reaction and heterotrophic denitrification reaction, and autotrophic denitrification reaction and heterotrophic denitrification reaction can be carried out in any order or in the same reaction tank. If they are carried out separately, when the autotrophic denitrification reaction is carried out, it can be completed in the autotrophic denitrification tank, wherein, after the membrane concentrate, nitrification liquid or heterotrophic denitrification liquid as described below enters the autotrophic denitrification tank, a microbial agent with anaerobic ammonia oxidizing bacteria as the core can be added to carry out autotrophic denitrification reaction to form an autotrophic denitrification liquid; when the heterotrophic denitrification reaction is carried out, it can be completed in the heterotrophic denitrification tank, wherein, after the membrane concentrate, nitrification liquid or autotrophic denitrification liquid enters the heterotrophic denitrification tank, a heterotrophic denitrification reaction is carried out to form a heterotrophic denitrification liquid.

[0037] For the sake of simplicity, in the present invention, the autotrophic denitrification reaction and the heterotrophic denitrification reaction are carried out in the same reaction tank (i.e., the denitrification tank). In the case where the source is a membrane concentrate, there will generally be trace or small amounts of particles with a particle size of 0.03 to 0.2 mm in the membrane concentrate. When the membrane concentrate or nitrification liquid enters the denitrification reaction step, the particle size of the previous particles will increase over time, and new particles will be generated in the denitrification liquid, and the newly generated particles will also increase over time. Therefore, the particles formed in the denitrification liquid will gradually form precipitation as the reaction time increases, and adhere to various areas in the denitrification tank. Such precipitation will also gather, block the pipeline, and affect the normal operation of the denitrification tank. It can often only be processed by further filtration separation or filter pressing. The present invention unexpectedly found that when the denitrification liquid is stirred using an internal circulation pump or a stirring rod to avoid the attachment of particles or the formation of precipitation, the efficiency of denitrification can be greatly promoted, and the improved efficiency is even higher than the technical solution of adding condensation nucleus materials to the denitrification liquid. The specific experimental settings are as follows:

[0038] Experimental group A: The inlet nitrogen load was 1 kg-N / (m 3 ·d) Start the internal circulation pump to stir the reaction liquid in the denitrification tank so that the generated particles do not precipitate. For example, the rotation speed is 30 to 60 rpm. No condensation nucleus material is added. The membrane concentrate from the upstream is subjected to denitrification reaction for one month, and the denitrification reaction is continued in this state.

[0039] Experimental group B was set up with an influent nitrogen load of 1 kg-N / (m 3 ·d) The membrane concentrate from the upstream was subjected to denitrification reaction for one month without using an internal circulation pump or adding condensation nucleus materials, and the denitrification reaction was continued in this state.

[0040] Experimental group C was set up with an inlet nitrogen load of 1 kg-N / (m 3 ·d) Without using the internal circulation pump and without adding condensation nucleus materials, the membrane concentrate from the upstream was subjected to denitrification for one month, and the internal circulation pump was turned on at the same speed as that of experimental group A to continue the denitrification reaction.

[0041] Experimental group D: The inlet nitrogen load was 1 kg-N / (m 3 ·d) Without using the internal circulation pump, 0.2 g / L zinc oxide with an average particle size of 50 mesh was added as the condensation nucleus material, and the membrane concentrate from the upstream was subjected to denitrification reaction for one month, and the denitrification reaction was continued in this state.

[0042] After 48 hours of treatment, the results of experimental groups A to D are as follows: the total nitrogen removal rate of experimental group A is 84%, the total nitrogen removal rate of experimental group B is 40%, the total nitrogen removal rate of experimental group C is 56%, and the total nitrogen removal rate of experimental group D is 66%. The above results show that the experimental group A, which increases the internal circulation of the denitrification pool to make the generated particles suspended without precipitation, can greatly improve the efficiency of denitrification treatment; while the experimental group C, which did not start the internal circulation in the first month and started the internal circulation later, could not achieve the efficiency of denitrification treatment to the effect of experimental group A due to the deposition of particles in the early stage, even if the internal circulation was turned on later.

[0043] Furthermore, set up experimental group E: Figure 1As shown, the membrane concentrate 1 from the upstream enters the body of the denitrification tank 2, and the internal circulation pump 3 for disturbing the denitrification liquid of the denitrification tank 2 body is turned on to suspend the particles brought by the upstream membrane concentrate 1 entering the body of the denitrification tank 2 or the newly generated particles. An overflow trough 4 is arranged on the upper part of the denitrification tank 2, and the denitrification tank 2 body is connected to the overflow trough 4 through the first orifice plate 5. Under the action of the inflow of the membrane concentrate 1 and the reflux of the swirl liquid from the swirl tank 9, the denitrification liquid in the denitrification tank 2 overflows to the overflow trough 4 to obtain the overflow liquid. Among them, the shape of the pores of the first orifice plate 5 can be circular or square, and the equivalent diameter can be 1.5 to 2 mm, so as to prevent the particles in the denitrification liquid in the denitrification tank 2 body that exceed the equivalent diameter of the pores from entering the overflow trough 4. The overflow trough 4 is provided with a water outlet 6 and a first pipe 8 connected to the swirl tank 9. Among them, a second orifice plate 7 is provided at the overflow trough 4 and the water outlet 6. The shape of the hole of the second orifice plate 7 can be circular or square, and the equivalent diameter can be as small as 0.05 mm and as large as 0.2 mm. A first reflux pump (not shown in the figure) is provided at the first pipeline 8 to pump the overflow liquid in the overflow trough 4 into the cyclone pool 9 to obtain a cyclone liquid. In the cyclone pool 9, the cyclone liquid containing particulate matter rapidly swirls to the water distributor 10 at a speed of more than 3 m / s, and then the cyclone liquid enters the diversion channel 11 connected to the water distributor 10. The liquid entering the diversion channel 11 is called diversion liquid. The diversion channel 11 can be a circular tube or a square tube, preferably a square tube. Among them, a hole is provided on the bottom plate 12 of the diversion channel 11, and the shape of the hole is circular or square, wherein the equivalent diameter of the hole of the bottom plate 12 is 1.5 to 2 mm, for example, 1.8 mm, and the diversion channel 11 is connected to the deposition bin 13 through the hole on its own bottom plate 12, and part of the diversion liquid containing particles falls into the deposition bin 13 through the hole on the bottom plate 12 of the diversion channel 11, thereby forming a first deposition liquid containing first shaped particles. Among them, when the particles in the diversion liquid pass through the hole on the bottom plate 12 of the diversion channel 11, the diversion liquid containing particles will produce a flow velocity difference due to the hole structure, thereby forming a regional pressure difference, causing the particles to collide with the edge of the hole, and the burr edge of the particles can be shaped by the collision. In addition, the upper surface area of ​​the hole will also have a flow velocity difference with the non-hole area (such as the upper surface or the side), and the flow velocity difference will also enhance the shaping effect of the particles. Regarding the diversion channel 11, it is connected to the second pipeline 16, and part of the diversion liquid is returned to the denitrification tank 2 by the action of the second reflux pump (not shown in the figure) arranged at the second pipeline 16. Regarding the sedimentation bin 13, a multi-layer structure is arranged in the sedimentation bin 13, for example, it can be a three-layer structure of an upper layer, a middle layer and a lower layer, wherein the upper layer and the middle layer are separated by a third orifice plate 14, and the middle layer and the lower layer are separated by a fourth orifice plate 15, and the third orifice plate 14 and the fourth orifice plate 15 are provided with circular or square channels.Among them, the equivalent diameter of the channel of the third orifice plate 14 is 1.0 to 1.5 mm, for example, 1.2 mm. The channel can make the first shaped particles falling into the upper layer of the sedimentation bin be further shaped and enter the middle layer of the sedimentation bin 13 with the first sedimentation liquid to form a second sedimentation liquid containing second shaped particles; the equivalent diameter of the channel of the fourth orifice plate 15 is 0.5 to 1.0 mm, for example, 0.6 mm. The channel can make the second shaped particles falling into the middle layer of the sedimentation bin 13 be further shaped and enter the lower layer of the sedimentation bin 13 with the second sedimentation liquid to form a third sedimentation liquid containing third shaped particles. The first sedimentation liquid in the upper layer and the second sedimentation liquid in the middle layer in the sedimentation bin 13 can be merged into the fifth pipe 19 through the third pipe 17 and the fourth pipe 18 under the action of the third reflux pump (not shown in the figure), and refluxed to the denitrification tank 2 through the fifth pipe 19; the third sedimentation liquid in the lower layer of the sedimentation bin 13 can enter the first pipe 8 connected to the sixth pipe 20 through the sixth pipe 20 under the action of the fourth reflux pump (not shown in the figure), so that the third sedimentation liquid merges with the overflow liquid and enters the vortex pool 9 together, thus forming an open circulation system.

[0044] Furthermore, an experimental group F is set up: the difference from the experimental group E is that the channels arranged on the bottom plate 12, the third orifice plate 14 and the fourth orifice plate 15 of the guide channel 11 can be lightning-shaped, star-shaped, triangle-shaped, diamond-shaped, elliptical, cross-circular, crescent-shaped, gear-shaped, sleeve-circular or double-arc plate-shaped special-shaped and different-diameter shaped channels, wherein the special-shaped means that at least two channels of the above-mentioned shapes are arranged on the same orifice plate, and the different-diameter means that at least two equivalent diameters of different sizes are arranged on the same orifice plate. Among them, the equivalent diameter of the special-shaped and different-diameter shaping channel of the bottom plate 12 of the guide channel 11 can be 1.5 to 2 mm, for example, it can be 1.6 mm and 1.8 mm; the equivalent diameter of the special-shaped and different-diameter shaping channel of the third orifice plate 14 can be 1.0 to 1.5 mm, for example, it can be 1.1 mm and 1.5 mm; the equivalent diameter of the special-shaped and different-diameter shaping channel of the fourth orifice plate 15 can be 0.5 to 1.0 mm, for example, it can be 0.5 mm and 1.0 mm. The channels provided on the bottom plate 12, the third orifice plate 14 and the fourth orifice plate 15 of the guide channel 11 can be, for example, Figure 2 As shown. Compared with traditional circular or square holes, special-shaped and different-diameter shaping channels can form a larger flow velocity difference on the channel surface, and then form a larger regional pressure difference, resulting in a strong collision between the particles and the edge of the channel, and a better shaping effect on the burr edge of the particles. In addition, the flow velocity difference between the channel area and the non-channel area will also enhance the shaping effect of the particles. In addition, due to the different shapes of the particles, at the same equivalent diameter, such as long strip particles, it will be easier to fall into the next layer, or get stuck in the notch area, thereby completing the reshaping. Among them, due to the characteristics of special-shaped and different-diameter channels, the third-shaped particles are mostly particles of different diameters.

[0045] After 30 days of continuous operation, experimental group E achieved the following better technical results compared with experimental group A: under continuous flow inflow, the total nitrogen removal rate of experimental group E reached more than 92%, significantly higher than 84% of experimental group A, and the protein and polysaccharide concentrations reached 390 mg·g-VSS. −1 , which is significantly higher than 268 mg·g-VSS in experimental group C −1 ; and experimental group F achieved better technical results than experimental group E: in experimental group F, the proportion of particles with an equivalent diameter of 2 to 3 mm in the denitrification tank exceeded 90% (by mass) of the total particles, which was much higher than the 40% in the denitrification tank of experimental group E; the MLVSS content in experimental group F reached 8300 mg / L, which was much higher than the 5600 mg / L of experimental group E, and the total nitrogen removal rate was also increased to more than 97%. The above shows that the particles that have been shaped into different shapes and diameters grow faster.

[0046] Preferably, the angle between the guide channel 11 and the horizontal plane may be in the range of 15 to 60°, which is more conducive to the shaping of the particles.

[0047] Preferably, a mesh drain with a hole of 3 mm in diameter or a square hole can be provided in the denitrification pool 2. The top of the mesh drain is open, and the internal reflux can be injected into the top of the mesh drain by the internal reflux pump, and the internal reflux injected into the mesh drain is discharged from the bottom or side of the mesh drain. Particles larger than 3 mm in the denitrification pool will be collected in the mesh drain and discharged every 2 to 4 months.

[0048] The above results show that while increasing the internal circulation of the denitrification tank to suspend the endogenous particles, adding a cyclone tank and the corresponding particle shaping channels, especially the special-shaped and different-diameter channels, can greatly improve the working efficiency of the denitrification treatment.

[0049] It should be pointed out that since the use of microbial agents for denitrification, especially autotrophic denitrification, is a routine operation in the art, the relevant description of the denitrification process in the above experimental groups A to F is omitted.

[0050] Although the present invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that various changes may be made without departing from the true spirit and scope of the present invention. In addition, the subject matter, spirit and scope of the present invention may be varied to accommodate specific situations, materials, material combinations and methods. All of these changes are included within the scope of the claims of the present invention.

Claims

1. A system for treating wastewater membrane concentrate by denitrification, comprising: A denitrification device receives an upstream liquid to be treated whose source is a membrane concentrated liquid, and denitrifies the upstream liquid to be treated in its body to form a denitrified liquid; A particle suspension device, which suspends endogenous particles in the denitrification liquid in the denitrification device body to improve the denitrification efficiency; An overflow tank, which is located at the upper part of the denitrification device, and the body of the denitrification device is connected to the overflow tank through a first orifice plate, and the overflow liquid generated by the overflow of the denitrification liquid enters the overflow tank; the equivalent diameter of the pores of the first orifice plate is 1.5 to 2 mm, so that the overflow liquid does not contain the endogenous particles with an equivalent diameter of more than 1.5 to 2 mm; A cyclone device, which is connected to the overflow tank through a first pipe, and the overflow liquid enters the cyclone device and then swirls to obtain a cyclone liquid; a water distributor, which is in communication with the cyclone device and allows the cyclone liquid to enter therein; A flow guide device, which is in communication with the water distributor, allowing the cyclone liquid to enter therein to obtain the flow guide liquid, wherein a channel is arranged on the bottom plate of the flow guide device; the channel of the bottom plate of the flow guide device is a first shaped channel, and the shape of the first shaped channel is at least two of a lightning shape, a star shape, a triangle, a diamond shape, an ellipse, a special-shaped circle, a crescent shape, a gear shape, a sleeve circle and an arc plate shape, and the equivalent diameter of the first shaped channel has at least two specifications; the equivalent diameter of the channel of the bottom plate of the flow guide device is 1.5 to 2 mm; A second pipeline is used to connect the denitrification device and the diversion device so that part of the diversion fluid flows back into the body of the denitrification device; The sedimentation bin is connected with the diversion device through the bottom plate of the diversion device, so that part of the diversion liquid falls into the sedimentation bin to form a sedimentation liquid containing shaped particles, and the sedimentation liquid is refluxed into the denitrification device.

2. The system according to claim 1, characterized in that The overflow trough also includes a water outlet, wherein a second orifice plate is arranged at the water outlet of the overflow trough, and the equivalent diameter of the pores of the second orifice plate is 0.05 to 0.2 mm.

3. The system according to claim 1, characterized in that The sedimentation chamber is divided into N layers, N is an integer greater than or equal to 2, each layer is separated by a perforated plate, and the equivalent diameter of the perforated channel of the first layer from top to bottom is smaller than the equivalent diameter of the perforated channel of the bottom plate of the flow guide device, and the equivalent diameter of the perforated channel of the underground layer between two adjacent layers of perforated plates is smaller than the equivalent diameter of the perforated channel of the upper layer; The deposition liquid in the deposition chamber enters the adjacent lower layer through the orifice plate between the layers. The deposition liquid in each layer is referred to as the first deposition liquid, the second deposition liquid, and so on from top to bottom.

4. The system according to claim 3, characterized in that When the sedimentation bin is divided into two layers, part of the first sedimentation liquid flows back to the denitrification device, and part of the first sedimentation liquid falls into the lower sedimentation bin to form a second sedimentation liquid, and the second sedimentation liquid merges with the overflow liquid and enters the cyclone device together; When the sedimentation bin is divided into three layers, part of the first sedimentation liquid flows back into the denitrification device, and part of the first sedimentation liquid falls into the middle sedimentation bin to form the second sedimentation liquid; Part of the second sedimentation liquid flows back to the denitrification device, and part of the second sedimentation liquid falls into the lower sedimentation bin to form a third sedimentation liquid. The third sedimentation liquid merges with the overflow liquid and enters the cyclone device together.

5. The system according to claim 3, characterized in that The channel of the orifice plate in the deposition chamber is a second shaped channel, and the shape of the second shaped channel is at least two of lightning shape, star shape, triangle shape, diamond shape, ellipse shape, irregular circle shape, crescent shape, gear shape, sleeve circle shape and arc plate shape, and the equivalent diameter specifications of the second shaped channel are at least two.

6. The system according to claim 3, characterized in that The equivalent diameter of the holes of the first layer of the orifice plate of the deposition chamber is 1 to 1.5 mm, and the equivalent diameter of the holes of the bottom layer of the orifice plate of the deposition chamber is 0.2 to 0.5 mm.

7. The system according to claim 1, characterized in that The angle between the flow guiding device and the horizontal plane is 15 to 60 degrees.

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