Tube-type dual-membrane ammonia nitrogen removal and recovery device

Abstract

The present invention discloses a tubular dual-membrane ammonia nitrogen removal and recovery device, which includes a housing, a cation exchange membrane, and a hollow fiber hydrophobic membrane arranged in sequence from outside to inside; a wastewater inlet chamber is formed between the housing and the cation exchange membrane; a driving chamber is formed between the cation exchange membrane and the hollow fiber hydrophobic membrane; a recovery chamber is formed inside the hollow fiber hydrophobic membrane; the hollow fiber hydrophobic membrane includes a plurality of bundle-shaped hollow membrane filaments, and a regulating device for adjusting the opening degree is provided corresponding to the acid solution inlet of the hollow fiber hydrophobic membrane, so that the number of membrane filaments participating in the acid solution contact work can be adjusted. Since the number of membrane filaments is adjustable, not only is the waste of acid solution and the pollution of membrane filaments greatly reduced, but also due to the setting of a plurality of membrane filaments, the efficient mass transfer of ammonia gas is realized, and the overall decontamination ability and recovery efficiency of the device are improved. In addition, due to the reasonable setting of an electric drive component, the present invention can form a composite drive of an electric field and a concentration field, thereby effectively treating high-concentration ammonia nitrogen wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of ecological environmental protection water treatment, and more specifically, to a tubular dual-membrane ammonia nitrogen removal and recovery device. Background Art

[0002] Ammonia nitrogen is one of the main factors causing water eutrophication. The effective treatment and resource utilization of ammonia nitrogen wastewater have important environmental and economic significance. Membrane technology, with its advantage of efficient separation, is widely used in the application of ammonia nitrogen removal / recovery in the field of water treatment. However, traditional membrane technology has problems such as easy membrane fouling and the trade-off between low energy consumption and high efficiency, and cannot achieve efficient removal and resource recovery of ammonia nitrogen. In recent years, under the background of the dual-carbon goal and the overall layout of ecological civilization construction, the use of membrane separation coupling technology instead of traditional single membrane separation technology, such as the combination of Donnan dialysis and osmotic distillation, provides a new solution for the treatment of ammonia nitrogen wastewater. By adding Donnan dialysis before osmotic distillation and using a cation exchange membrane to isolate anions and some high-valent metal cations, ammonia nitrogen is enriched from the sewage, so that the sewage does not directly contact the breathable hydrophobic membrane, achieving the purpose of slowing down the fouling of the hydrophobic membrane; the enriched ammonia nitrogen is converted into ammonia gas under alkaline conditions, and then the ammonia gas crosses the hydrophobic membrane and enters the recovery area. This coupling technology can make full use of the advantages of the membrane separation process, is driven by the natural concentration difference or pressure difference, does not require external energy input, can achieve green and low-carbon ammonia nitrogen enrichment and resource recovery under "zero energy consumption" conditions, reduce the operating cost, and has good economic efficiency and environmental friendliness.

[0003] The coupled component of Donnan dialysis and osmotic distillation uses a combination of a cation exchange membrane and a breathable hydrophobic membrane. The common form of the cation exchange membrane is flat, and the common forms of the breathable hydrophobic membrane are flat or hollow fiber. The flat cation exchange membrane and the breathable hydrophobic membrane have the following problems: The membrane is easily wetted. The surface area of the flat membrane module is usually large, with a wide contact area with the liquid and a long liquid flow path, resulting in easy wetting of the membrane surface and affecting the transmembrane transport of ions or gases; The membrane flux is small. The structural design of the flat membrane module usually limits the flow mode and speed of the liquid or gas, resulting in reduced mass transfer efficiency and decreased membrane flux. In addition, concentration polarization is likely to occur during the transmembrane transport of ions in the flat membrane module, which also leads to a decrease in membrane flux; The driving force of the membrane process is low. The existing flat membrane modules are difficult to have an optimized hydrodynamic design, resulting in limitations and singularity in the flow of wastewater during operation and a low driving force for the membrane separation process; The integration (packing) density is low. Due to the relatively small membrane area per unit volume of the flat membrane module, more membrane area cannot be packed in the flat module within a certain space. At the same time, the coupled component of Donnan dialysis and osmotic distillation composed of a series connection of a flat cation exchange membrane and a flat hydrophobic membrane module has the above-mentioned disadvantages of a single flat membrane module, such as easy contamination and wetting of the membrane, small membrane flux, low driving force of the membrane process, low integration density, large floor area, etc. In addition, due to the large plane distance between the flat membrane modules, local eddies and dead zones are likely to occur when the wastewater passes through, and pollutants often accumulate in these areas, resulting in membrane blockage and pollution problems. In particular, fouling is likely to occur at the four dead corners and is not easy to clean, requiring special chemicals and procedures for cleaning, resulting in increased costs. And the existing coupled components of Donnan dialysis and osmotic distillation are all combined, requiring pipe fittings for connection, occupying a large area, and having a slow overall mass transfer and reaction rate, affecting the separation performance of ammonia nitrogen.

[0004] In summary, the above problems restrict the application and popularization of the flat coupled component of Donnan dialysis and osmotic distillation for the removal and recovery of ammonia nitrogen. There is no technology yet to realize other shaped membrane modules for the coupling of Donnan dialysis and osmotic distillation. Summary of the Invention

[0005] Based on the above technical problems, the purpose of the present invention is to provide a tubular dual-membrane ammonia nitrogen removal and recovery device, which can overcome the defects of the existing flat components for the coupling of Donnan dialysis and osmotic distillation. The entire decontamination process is carried out under natural concentration difference and / or electric drive, realizing efficient ammonia nitrogen removal and resource recovery.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] The present invention discloses a tubular dual-membrane ammonia nitrogen removal and recovery device, which includes a housing, a cation exchange membrane, and a hollow fiber hydrophobic membrane. The housing has a hollow inner cavity; the cation exchange membrane is of a tubular structure and is disposed in the hollow inner cavity of the housing; the hollow fiber hydrophobic membrane is of a tubular structure and is disposed in the inner cavity of the cation exchange membrane; a wastewater inlet chamber is formed between the housing and the cation exchange membrane; a driving chamber is formed between the cation exchange membrane and the hollow fiber hydrophobic membrane; a recovery chamber is formed inside the hollow fiber hydrophobic membrane; wherein, the wastewater inlet chamber is configured to receive the input of the ammonia nitrogen wastewater to be treated, the driving chamber is configured to receive the input of an external driving liquid, the recovery chamber is configured to receive the input of an external acid solution and output ammonium salt outward; the hollow fiber hydrophobic membrane includes a plurality of tightly arranged bundle-shaped hollow membrane filaments, and a regulating device capable of adjusting the opening degree of the acid solution inlet is provided corresponding to the acid solution inlet of the hollow fiber hydrophobic membrane, so that the number of membrane filaments participating in the acid solution contact work in all the bundle-shaped hollow membrane filaments can be adjusted.

[0008] The so-called tubular structure refers to a structure with an annular radial cross-section. In the present invention, the housing, the cation exchange membrane, and the hollow fiber hydrophobic membrane are arranged in sequence from the inside to the outside, and there is a chamber (i.e., the wastewater inlet chamber) between the housing and the cation exchange membrane, there is a chamber (i.e., the driving chamber) between the cation exchange membrane and the hollow fiber hydrophobic membrane, and there is a chamber (i.e., the recovery chamber) inside the hollow fiber hydrophobic membrane, so that the device of the present invention is configured as a three-chamber two-membrane structure with layers of rings.

[0009] In the above solution, the ammonia nitrogen wastewater to be treated enters the housing from the wastewater inlet chamber. The ammonium ions contained in the ammonia nitrogen wastewater to be treated enter the driving chamber through the cation exchange membrane under the action of the concentration difference (i.e., the natural concentration difference). The driving liquid in the driving chamber is an alkaline liquid, which reacts with the entering ammonium ions to generate ammonia water. The ammonia water decomposes into ammonia gas and water. Due to the difference in ammonia partial pressure between the driving chamber and the recovery chamber, the ammonia gas enters the recovery chamber through the hollow fiber hydrophobic membrane, contacts the bundle-shaped hollow membrane filaments regulated by the regulating device in the recovery chamber, and enters the bundle-shaped hollow membrane filaments participating in the acid solution contact work. Finally, it reacts under the action of the acid solution to generate liquid ammonium salt and is recovered.

[0010] During the deammoniation process, the limited ammonia mass transfer rate is the pervaporation (OD) process, that is, the process of ammonia gas passing through the hollow fiber hydrophobic membrane (GPM). In the prior art, the area of the cation exchange membrane (CEM) is larger than that of the hollow fiber hydrophobic membrane (GPM), which is not conducive to the ammonia mass transfer process. In the device of the present invention, since the device is constructed such that a single cation exchange membrane corresponds to a plurality of hollow fiber hydrophobic membranes, that is, it is constructed in the form of "1 to N", compared with the prior art where the area of the hollow fiber hydrophobic membrane (GPM) is smaller than that of the cation exchange membrane (GPM), it can provide a larger membrane contact area for the process of ammonia gas passing through the hollow fiber hydrophobic membrane (GPM), thereby promoting the transfer of ammonia gas from the driving chamber to the recovery chamber during the deammoniation process, and further improving the ammonia mass transfer efficiency.

[0011] Moreover, since the number of bundled hollow membrane filaments participating in the acid solution contact work in the hollow fiber hydrophobic membrane can be regulated, when some of the bundled hollow membrane filaments are contaminated, the other bundled hollow membrane filaments can still carry out the mass transfer process normally, avoiding the risk of membrane contamination of the entire system and improving the reliability of the device operation.

[0012] In the tubular dual-membrane ammonia nitrogen removal and recovery device disclosed according to the present invention, the regulating device is constructed to be able to determine the opening degree of the acid solution inlet of the central control fiber hydrophobic membrane based on the concentration of the ammonia nitrogen wastewater to be treated.

[0013] That is, the regulating device of the present invention can adapt to the change in the concentration of the ammonia nitrogen wastewater to be treated and adjust the opening degree of the acid solution inlet of the hollow fiber hydrophobic membrane according to the change in the concentration of the ammonia nitrogen wastewater to be treated. When the concentration of the ammonia nitrogen wastewater becomes higher, the opening degree of the acid solution inlet of the hollow fiber hydrophobic membrane adjusted by the regulating device becomes larger, so that the number of membrane filaments participating in the acid solution contact work in the bundled hollow membrane filaments increases; when the concentration of the ammonia nitrogen wastewater becomes lower, the opening degree of the acid solution inlet of the hollow fiber hydrophobic membrane adjusted by the regulating device becomes smaller, so that the number of membrane filaments participating in the acid solution contact work in the bundled hollow membrane filaments decreases. That is to say, the regulating device of the present invention can regulate the number of membrane filaments participating in the acid solution contact work in the bundled hollow membrane filaments according to the change in the concentration of the ammonia nitrogen wastewater to be treated, thereby improving the operation flexibility of the device of the present invention.

[0014] And since the opening degree of the acid solution inlet of the hollow fiber hydrophobic membrane adjusted by the regulating device is determined based on the concentration of the ammonia nitrogen wastewater to be treated, the opening of the acid solution inlet of the hollow fiber hydrophobic membrane corresponds to the bundled hollow membrane filaments to be involved in the work, so that the number of membrane filaments participating in the acid solution contact work in the bundled hollow membrane filaments is determined based on the concentration of the ammonia nitrogen wastewater to be treated, thereby effectively avoiding the waste of acid solution and the contamination of the bundled hollow membrane filaments and saving economic costs.

[0015] In the present invention, the opening degree of the acid solution inlet of the hollow fiber hydrophobic membrane is actually the size of the opening of the regulating device.

[0016] In a specific embodiment, the opening of the regulation device corresponds to the bundle of hollow membrane filaments to be involved in the work, and the external acid solution enters the bundle of hollow membrane filaments to be involved in the work through the opening of the regulation device. When the opening of the regulation device is larger, the number of the bundle of hollow membrane filaments corresponding to the opening is more, so that the number of the bundle of hollow membrane filaments to be involved in the work is more; when the opening of the regulation device is smaller, the number of the bundle of hollow membrane filaments corresponding to the opening is less, so that the number of the bundle of hollow membrane filaments to be involved in the work is less. Therefore, the size of the opening of the regulation device is positively correlated with the number of the bundle of hollow membrane filaments to be involved in the work.

[0017] In the present invention, the size of the opening of the regulation device is determined based on the concentration of the ammonia nitrogen wastewater to be treated. Specifically, the concentration of the ammonia nitrogen wastewater to be treated is mainly divided into low-concentration ammonia nitrogen wastewater, medium-concentration ammonia nitrogen wastewater and high-concentration ammonia nitrogen wastewater. The opening of the regulation device can be adjusted to 20%, 50%, 100%, etc. Among them, the opening of the regulation device being 20% corresponds to the low-concentration ammonia nitrogen wastewater, the opening of the regulation device being 50% corresponds to the medium-concentration ammonia nitrogen wastewater, and the opening of the regulation device being 100% corresponds to the high-concentration ammonia nitrogen wastewater.

[0018] Furthermore, when the size of the opening of the regulation device is 20%, the bundle of hollow membrane filaments to be involved in the work is the hollow fiber membrane filaments corresponding to the 20% opening size; when the size of the opening of the regulation device is 50%, the bundle of hollow membrane filaments to be involved in the work is the hollow fiber membrane filaments corresponding to the 50% opening size; when the size of the opening of the regulation device is 100%, the bundle of hollow membrane filaments to be involved in the work is the hollow fiber membrane filaments corresponding to the 100% opening size. That is, the bundle of hollow membrane filaments involved in the acid solution contact work is determined according to the concentration of the ammonia nitrogen wastewater to be treated.

[0019] In the tubular dual-membrane ammonia nitrogen removal and recovery device disclosed according to the present invention, the regulation device includes a dial, a chassis and a plurality of opening and closing blades. Sliding grooves are respectively formed on the dial and the chassis. The sliding grooves of the dial and the chassis are at a certain angle in space. A sliding column is arranged on the opening and closing blade, and the sliding column is positioned in the sliding groove. The chassis can be driven to rotate, and the sliding column slides in the sliding groove through the rotation of the chassis. By means of the repeated sliding of the sliding column in the sliding groove, the opening and closing blades approach and move away from the central position, so as to adjust the opening range of the regulation device.

[0020] In the tubular dual-membrane ammonia nitrogen removal and recovery device disclosed according to the present invention, the number of the sliding grooves arranged on the dial, the number of the sliding grooves arranged on the chassis and the number of the sliding columns arranged on the blades correspond one by one.

[0021] In the tubular dual-membrane ammonia nitrogen removal and recovery device disclosed according to the present invention, an acid distributor is provided above the regulation device, and the acid distributor inputs external acid solution into the bundle of hollow membrane filaments of the hollow fiber hydrophobic membrane through the opening and closing port of the regulation device.

[0022] In the prior art for treating ammonia nitrogen wastewater, either based on concentration difference driving (i.e., natural concentration difference driving) or based on electric driving, there is a lack of an ammonia nitrogen wastewater treatment device that effectively combines the two driving methods and has a reasonable structure. Moreover, when treating high-concentration ammonia nitrogen wastewater in the prior art, relying solely on concentration difference driving will cause problems such as low system mass transfer rate and limited treatment capacity. Even if this contradiction can be alleviated in the prior art by the conventional method of laying more components, it will increase the engineering investment cost. To solve these problems, in the tubular dual-membrane ammonia nitrogen removal and recovery device disclosed according to the present invention, an electric driving component is further included. The electric driving component includes: an anode metal mesh, which is configured as a tubular structure and is disposed between the outer shell and the cation exchange membrane; a cathode metal mesh, which is configured as a tubular structure and is disposed between the cation exchange membrane and the hollow fiber hydrophobic membrane; the anode metal mesh is connected to the positive pole of the power supply, and the cathode metal mesh is connected to the negative pole of the power supply. When the anode metal mesh and the cathode metal mesh are energized, the wastewater inlet chamber forms an anode chamber, and the driving chamber can form a cathode chamber. Based on this structural setting, when the concentration of ammonia nitrogen wastewater is high, the present invention can apply electric driving simultaneously. Then, the technology of the present invention changes from simply coupling Donnan dialysis and pervaporation to remove and recover ammonia nitrogen to electro-dialysis-Donnan dialysis composite driving and coupling with pervaporation to remove and recover ammonia nitrogen. That is, the technical implementation path of the present invention becomes a tubular dual-membrane ammonia nitrogen removal and recovery device driven by a composite of an electric field and a concentration field. That is, in the present invention, more efficient ammonia nitrogen mass transfer can be achieved through electric driving (such as electro-dialysis). This enables the flexible adjustment of electric driving and concentration difference driving in the present invention. When treating high-concentration ammonia nitrogen wastewater, if the effect of concentration difference driving is not ideal, it can be switched to the composite driving of the electric field and the concentration field to recover ammonia nitrogen.

[0023] Among them, based on the aforementioned electric drive component, in the present invention, an anode chamber is formed between the anode metal mesh and the cation exchange membrane, and a cathode chamber is formed between the cation exchange membrane and the cathode metal mesh. The anode chamber is located in the waste water inlet chamber, and the cathode chamber is located in the drive chamber. In the anode chamber, an oxygen evolution reaction occurs on the anode metal mesh, and water molecules lose electrons and are oxidized to generate oxygen and hydrogen ions. In the cathode chamber, a hydrogen evolution reaction occurs on the cathode metal mesh, and water molecules gain electrons and are reduced to generate hydrogen and hydroxide ions. The specific working process is as follows: First, the ammonia-containing waste liquid enters the anode chamber, and ammonium ions enter the cathode chamber through the cation exchange membrane under the drive of an external electric field. Secondly, the ammonium ions combine with the hydroxide ions generated by the cathode metal mesh to form free gaseous ammonia molecules. Due to the difference in ammonia partial pressure between the cathode chamber and the recovery chamber, the ammonia enters the recovery chamber. Then, the gaseous ammonia combines with the hydrogen ions in the acid solution in the recovery chamber to form ammonium ions, and finally is recovered in the form of liquid ammonium salt.

[0024] The electric drive for ammonia nitrogen recovery in the present invention enables the ammonium ions in the waste water inlet chamber to migrate directionally through the electric field generated by the provided anode metal mesh and cathode metal mesh, greatly accelerating the speed of ammonium ions passing through the cation exchange membrane, improving the deammoniation efficiency and the overall operation efficiency of the device. Moreover, the hydroxide ions generated on the cathode metal mesh in the drive chamber can directly react with the ammonium ions migrating from the waste water inlet chamber to generate ammonia, reducing the consumption of chemical reagents and being environmentally friendly. And the provided cathode metal mesh shortens the distance from the hollow fiber hydrophobic membrane, enabling the ammonia generated near the cathode metal mesh to be quickly transferred into the hollow fiber hydrophobic membrane under the action of the electric field, effectively avoiding the problems of ammonia accumulation and reverse diffusion, thereby improving the removal efficiency and stability of the entire system. In addition, under the action of the electric field, the negatively charged organic molecule in the waste water inlet chamber moves towards the anode metal mesh, avoiding contact with the cation exchange membrane, thereby reducing the risk of contamination of the cation exchange membrane. At the same time, it can also avoid the problem of reduced membrane flux caused by the interaction between the negatively charged organic molecule and the cation exchange membrane, affecting the mass transfer efficiency. Finally, the device of the present invention can flexibly adjust operating parameters such as voltage and current according to the concentration change of the ammonia nitrogen waste water to be treated, improving the response ability of the device, enabling it to maintain the best treatment performance under various environmental conditions, and achieving efficient removal of ammonia nitrogen.

[0025] In the tubular dual-membrane ammonia nitrogen removal and recovery device disclosed according to the present invention, the anode metal mesh is a titanium mesh coated with an Ir mixed metal oxide, and / or, the cathode metal mesh is a stainless steel diamond grid mesh.

[0026] In the tubular dual-membrane ammonia nitrogen removal and recovery device disclosed according to the present invention, a spiral water inlet corridor for receiving the input of ammonia nitrogen wastewater to be treated is provided in the wastewater inlet chamber, and the spiral water inlet corridor is spirally wound from top to bottom along the outer side of the cation exchange membrane. The provided spiral water inlet corridor extends the inflow path of the ammonia nitrogen wastewater to be treated, increases the contact time with the cation exchange membrane, and improves the mass transfer efficiency and deammonification efficiency; moreover, the formed spiral flow field can enhance the turbulent flow, reduce the concentration polarization phenomenon occurring on the surface of the cation exchange membrane; and the spiral water inlet can also increase the tangential flow velocity of the water flow, has a scouring effect on the cation exchange membrane, and reduces the deposition of pollutants on the surface of the cation exchange membrane; in addition, the spiral water inlet corridor can also make the ammonia nitrogen wastewater flow more evenly over the surface of the cation exchange membrane, reduce the formation of local high-concentration areas, thereby reducing the risk of the cation exchange membrane being contaminated and extending the service life of the cation exchange membrane.

[0027] In the tubular dual-membrane ammonia nitrogen removal and recovery device disclosed according to the present invention, the spiral angle of the spiral water inlet corridor is 15° to 25°, and the angle between the spiral water inlet corridor and the cation exchange membrane is 45°. A smaller spiral angle can maintain the stability of the flow of the ammonia nitrogen wastewater, while a larger spiral angle can increase the tangential velocity of the fluid, thereby enhancing the shear force and realizing the scouring of the pollutants on the surface of the cation exchange membrane. Preferably, the spiral angle of the spiral water inlet corridor is 15° to 25°; and the angle between the spiral water inlet corridor and the cation exchange membrane is 45°, which can form an impact force in the tangential direction, has a scouring effect on the cation exchange membrane, and avoids the cation exchange membrane being contaminated.

[0028] In the tubular dual-membrane ammonia nitrogen removal and recovery device disclosed according to the present invention, a mesh support member is provided on the outer side and / or the inner side of the cation exchange membrane. The provided mesh support member can evenly disperse the pressure impact caused by the inflow of the ammonia nitrogen wastewater to be treated on the cation exchange membrane, effectively avoiding the risk of damage to the surface of the cation exchange membrane due to excessive local pressure; moreover, the geometric configuration of the mesh support member reduces the pressure drop in the flow channel, reduces the energy consumption; and can also improve the additional mechanical strength, helping to maintain the stability of the system in the face of fluid pressure fluctuations. Among them, the thickness of the mesh support member can be 1 to 3 mm.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1) The present invention innovatively provides an ammonia nitrogen wastewater treatment and recovery device, whose overall structure is a tubular structure with three chambers and two membranes, thus forming an integrated device based on the coupling of Donnan dialysis and osmotic distillation. By adjusting the device, the opening degree of the acid liquid inlet of the hollow fiber hydrophobic membrane is adjusted, so that the number of membrane filaments participating in the acid liquid contact work in the bundle of hollow membrane filaments of the hollow fiber hydrophobic membrane can be adjusted, improving the flexibility of the entire device in operation; and by adjusting the contact between the bundle of hollow membrane filaments and the acid liquid through the adjusting device, the waste of acid liquid and the pollution of the bundle of hollow membrane filaments can also be reduced, saving economic costs.

[0031] 2) In the device of the present invention, since the device structure is that a single cation exchange membrane corresponds to a number of hollow fiber hydrophobic membranes, that is, it is structured in the form of "1 to N". Compared with the prior art where the area of the hollow fiber hydrophobic membrane is smaller than that of the cation exchange membrane, it can provide a larger membrane contact area for the ammonia gas during the process of passing through the hollow fiber hydrophobic membrane, thereby promoting the transfer of ammonia gas from the driving chamber to the recovery chamber during the deammoniation process, and further improving the mass transfer efficiency of ammonia gas.

[0032] 3) In the device of the present invention, since the number of the bundle of hollow membrane filaments participating in the acid liquid contact work in the hollow fiber hydrophobic membrane can be adjusted, when some of the bundle of hollow membrane filaments are contaminated, the other bundle of hollow membrane filaments can still carry out the mass transfer process normally, avoiding the risk of the entire system's membrane being contaminated and improving the reliability of the device operation.

[0033] The tubular dual-membrane ammonia nitrogen removal and recovery device of the present invention will be detailedly disclosed below in combination with the embodiments shown in the accompanying drawings and the reference numerals. Description of the Drawings

[0034] Figure 1 It is a sectional view of the device of the present invention;

[0035] Figure 2 It is a top view of the device of the present invention;

[0036] Figure 3 It is a schematic diagram of the state when the opening size of the opening and closing port of the adjusting device of the present invention is 20%;

[0037] Figure 4 It is a schematic diagram of the state when the opening size of the opening and closing port of the adjusting device of the present invention is 30%;

[0038] Figure 5 It is a schematic diagram of the state when the opening size of the opening and closing port of the adjusting device of the present invention is 100%;

[0039] Figure 6 It is a schematic diagram of the structural cooperation between the opening and closing blades and the dial of the adjusting device of the present invention;

[0040] Figure 7 It is a schematic diagram of the structural cooperation between the opening and closing blades and the chassis of the adjusting device of the present invention;

[0041] Figure 8 This is a structural schematic diagram of the spiral water inlet corridor provided in the wastewater inlet chamber of the present invention.

[0042] Reference numerals

[0043] 1. Housing, 2. Cation exchange membrane, 3. Hollow fiber hydrophobic membrane, 4. Wastewater inlet chamber, 5. Driving chamber, 6. Recovery chamber, 7. Bundle of hollow membrane filaments, 8. Paddle, 9. Chassis, 10. Opening and closing blades, 11. Slide post, 12. Anode metal mesh, 13. Cathode metal mesh, 14

[0044] Spiral water inlet corridor, 15. Mesh support member, 16. Arc-shaped guide chute, 17. Strip-shaped guide chute, 18. Chassis handle, 19. Ammonia nitrogen wastewater inlet, 20. Ammonia nitrogen wastewater outlet, 21. Driving liquid inlet, 22. Driving liquid outlet, 23. Acid liquid inlet, 24. Liquid ammonium salt outlet. Specific embodiments

[0045] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other.

[0046] Aiming at the defects of the existing flat plate type component of the coupling of Donnan dialysis and osmotic distillation, the present invention discloses a tubular dual-membrane ammonia nitrogen removal and recovery device. The process of removing pollutants by this device can be carried out under the drive of natural concentration difference or pressure difference without external energy input, and green and low-carbon ammonia nitrogen removal and resource recovery can be realized under the condition of "zero energy consumption".

[0047] Such as Figure 1 And Figure 2As shown in the figure, the tubular dual-membrane ammonia nitrogen removal and recovery device disclosed by the present invention includes a housing 1, a cation exchange membrane 2, and a hollow fiber hydrophobic membrane 3. The housing 1 has a hollow inner cavity. The cation exchange membrane 2 is of a tubular structure and is arranged in the hollow inner cavity of the housing 1. The hollow fiber hydrophobic membrane 3 is of a tubular structure and is arranged in the inner cavity of the cation exchange membrane 2. A wastewater inlet chamber 4 is formed between the housing 1 and the cation exchange membrane 2. A driving chamber 5 is formed between the cation exchange membrane 2 and the hollow fiber hydrophobic membrane 3. A recovery chamber 6 is formed inside the hollow fiber hydrophobic membrane 3. Among them, the wastewater inlet chamber 4 is configured to be able to receive the input of the ammonia nitrogen wastewater to be treated. The driving chamber 5 is configured to be able to receive the input of an external driving liquid. The recovery chamber 6 is configured to be able to receive the input of an external acid solution and output ammonium salt outward. The hollow fiber hydrophobic membrane 3 includes a number of closely arranged bundle-shaped hollow membrane filaments 7. A regulating device capable of adjusting the opening degree of the acid solution inlet is provided corresponding to the acid solution inlet of the hollow fiber hydrophobic membrane 3, so that the number of membrane filaments participating in the acid solution contact work in all the bundle-shaped hollow membrane filaments 7 can be adjusted.

[0048] Among them, the wastewater inlet chamber 4 has an ammonia nitrogen wastewater inlet 19 and an ammonia nitrogen wastewater outlet 20. The driving chamber 5 has a driving liquid inlet 21 and a driving liquid outlet 22. The recovery chamber has an acid solution inlet 23 and a liquid ammonium salt outlet 24. The ammonia nitrogen wastewater inlet 19 and the acid solution inlet 23 are located on the upper side of the housing 1. The ammonia nitrogen wastewater outlet 20 and the liquid ammonium salt outlet 24 are located on the lower side of the housing 1. The driving liquid inlet 21 and the driving liquid outlet 22 are respectively located on the upper left side and the lower right side of the housing 1.

[0049] In the present invention, the material of the housing 1 can be selected from polyethylene, polypropylene, stainless steel, etc. The cation exchange membrane 2 and the hollow fiber hydrophobic membrane 3 are nested in structure and are sealed by sealant and sealing rings. Sealing rings are provided at both top ends to ensure the tightness of the components. The way for the ammonia nitrogen wastewater to enter the membrane module is peripheral water inlet, and the way for the liquid ammonium salt to flow out is central water outlet.

[0050] In the embodiment of the present invention, the driving liquid in the driving chamber 5 is one of soda solution, waste alkali solution, and saline-alkali solution, such as common soda or waste alkali solutions like sodium hydroxide (NaOH), potassium hydroxide (KOH), etc. Among them, the ratio of ammonium ion to hydroxide ion in the saline-alkali solution can be 1:1 to 2, such as 1:1, 1:1.2, and 1:1.5, etc. The molar concentration ratio of the cation in the driving liquid to the ammonia nitrogen in the wastewater to be treated is 1:1 to 100, such as 1:20, 1:40, 1:60, etc. By adjusting the ratio, the ammonia nitrogen removal efficiency can be improved under the condition of low cost. In this embodiment, the ammonium ions in the wastewater inlet chamber 4 and the driving ions in the driving chamber 5 undergo displacement across the cation exchange membrane 2 under the action of concentration difference. Under alkaline conditions, the ammonium ions passing through the cation exchange membrane 2 are converted into ammonia gas.

[0051] In the embodiment of the present invention, the acid solution in the recovery chamber 6 is one or a mixture of common acid solutions such as sulfuric acid (H2SO4) and hydrochloric acid (HCl). Among them, the ratio of the multiple mixed acid solutions can be 1:1 to 2, such as 1:1, 1:1.2, and 1:1.5, etc. Different high-concentration ammonium salt products can be obtained through different acid solutions. The molar concentration ratio of hydrogen ions in the acid solution to ammonia nitrogen in the wastewater to be treated is 1:1 to 2.5, such as 1:1, 1:1.5, 1:2, etc. By adjusting the ratio, the recovery efficiency of ammonia nitrogen can be improved under low-cost conditions. In this embodiment, ammonia gas transfers across the hollow fiber hydrophobic membrane 3 under the action of the pressure difference on both sides of the hollow fiber hydrophobic membrane 3 and then is converted into an ammonium salt product.

[0052] Preferably, a driving pump is arranged in the driving chamber 5 to control the flow rate of the driving liquid and reduce the phenomenon of concentration polarization on the membrane surface of the cation exchange membrane 2.

[0053] The cation exchange membrane 2 of the present invention can selectively permeate cations and intercept anions. The driving force is concentration driving, and no energy consumption is generated; the main component of the hollow fiber hydrophobic membrane 3 is PVDF, which has high mechanical strength, acid and alkali resistance, and strong impact resistance; the sealant can form a sealing layer through spraying / smearing and baking processes to enhance the sealing effect and ensure the sealing performance of the membrane module.

[0054] In the present invention, the opening degree of the acid solution inlet of the hollow fiber hydrophobic membrane 3 is adjusted by a regulating device, so that the number of membrane filaments participating in the acid solution contact work in the bundle of hollow membrane filaments 7 of the hollow fiber hydrophobic membrane 3 can be adjusted, which improves the flexibility of the entire device in operation; and by regulating the contact between the bundle of hollow membrane filaments 7 and the acid solution through the regulating device, the waste of the acid solution and the pollution of the bundle of hollow membrane filaments 7 can also be reduced, saving economic costs;

[0055] Secondly, the device of the present invention constructs a single cation exchange membrane 2 corresponding to a plurality of hollow fiber hydrophobic membranes 3, that is, it is constructed in the form of "1 to N". Compared with the prior art where the area of the hollow fiber hydrophobic membrane is smaller than the area of the cation exchange membrane, it can provide a larger membrane contact area for the ammonia gas passing through the hollow fiber hydrophobic membrane 3, thereby promoting the transfer of ammonia gas from the driving chamber 5 to the recovery chamber 6 during the deammoniation process, and further improving the mass transfer efficiency of ammonia gas;

[0056] In addition, since the number of the bundle of hollow membrane filaments 7 participating in the acid solution contact work in the hollow fiber hydrophobic membrane 3 can be regulated, when some of the bundle of hollow membrane filaments 7 are contaminated, the other bundle of hollow membrane filaments 7 can still carry out the mass transfer process normally, avoiding the risk of membrane contamination of the entire system and improving the reliability of the device operation.

[0057] Such as Figures 3 - 5As shown, in a preferred embodiment, the size of the opening of the regulating device is determined based on the concentration of the ammonia nitrogen wastewater to be treated. Specifically, the concentration of the ammonia nitrogen wastewater to be treated is mainly divided into low-concentration ammonia nitrogen wastewater, medium-concentration ammonia nitrogen wastewater, and high-concentration ammonia nitrogen wastewater. The opening of the regulating device can be adjusted to 20%, 50%, 100%, etc. Among them, the opening of the regulating device being 20% corresponds to low-concentration ammonia nitrogen wastewater, the opening of the regulating device being 50% corresponds to medium-concentration ammonia nitrogen wastewater, and the opening of the regulating device being 100% corresponds to high-concentration ammonia nitrogen wastewater.

[0058] Furthermore, when the concentration of low-concentration ammonia nitrogen wastewater becomes higher to medium-concentration ammonia nitrogen wastewater, the size of the opening of the regulating device is adjusted from 20% to 50%. When the concentration of medium-concentration ammonia nitrogen wastewater becomes higher to high-concentration ammonia nitrogen wastewater, the size of the opening of the regulating device is adjusted from 50% to 100%. Conversely, when the concentration of high-concentration ammonia nitrogen wastewater becomes lower to medium-concentration ammonia nitrogen wastewater, the size of the opening of the regulating device is adjusted from 100% to 50%. When the concentration of medium-concentration ammonia nitrogen wastewater becomes lower to low-concentration ammonia nitrogen wastewater, the size of the opening of the regulating device is adjusted from 50% to 20%. The adjustment of the size of the opening of the regulating device is based on the actual situation.

[0059] In the present invention, the opening of the regulating device is the opening of the acid solution inlet of the hollow fiber hydrophobic membrane 3, that is, the size of the opening of the acid solution inlet of the hollow fiber hydrophobic membrane 3 is determined based on the concentration of the ammonia nitrogen wastewater to be treated. The regulating device can determine the opening degree of the acid solution inlet of the hollow fiber hydrophobic membrane 3 according to the concentration of the ammonia nitrogen wastewater to be treated.

[0060] The present invention controls the number of the bundle-shaped hollow membrane filaments 7 participating in the acid solution contact work by the size of the opening of the regulating device. The larger the opening of the regulating device, the more the corresponding number of the bundle-shaped hollow membrane filaments 7 to be regulated, and the more the number of the bundle-shaped hollow membrane filaments 7 participating in the acid solution contact work. The smaller the opening of the regulating device, the fewer the corresponding number of the bundle-shaped hollow membrane filaments 7 to be regulated, and the fewer the number of the bundle-shaped hollow membrane filaments 7 participating in the acid solution contact work. And the size of the opening of the regulating device is determined based on the concentration of the ammonia nitrogen wastewater to be treated. Thus, the number of the bundle-shaped hollow membrane filaments 7 participating in the acid solution contact work is determined based on the concentration of the ammonia nitrogen wastewater to be treated, and further, it can effectively avoid the waste of the acid solution and the pollution of the bundle-shaped hollow membrane filaments 7, saving economic costs.

[0061] Such as Figure 6 And Figure 7As shown, in the embodiment of the present invention, the regulating device includes a paddle 8, a chassis 9 and a plurality of opening and closing blades 10, the paddle 8 is provided with an arc-shaped guide slot 16, the chassis 9 is provided with a strip-shaped guide slot 17, the arc-shaped guide slot 16 and the strip-shaped guide slot 17 form a certain angle in space, a slide column 11 is provided through the opening and closing blade 10, and the two ends of the slide column 11 are respectively positioned in the arc-shaped guide slot 16 and the strip-shaped guide slot 17, and a chassis handle 18 is provided on the end surface of the chassis 9. The chassis handle 18 is toggled to open and close the blade 10. 8 makes the chassis 9 rotate, and under the action of the rotation of the chassis 9, the slide post 11 slides in the arc-shaped guide slot 16 and the strip-shaped guide slot 17 at the same time. Since the arc-shaped guide slot 16 and the strip-shaped guide slot 17 form a certain angle in space, under the constraint of the slots of the two, when the slide post 11 slides repeatedly in the arc-shaped guide slot 16 and the strip-shaped guide slot 17 at the same time, the opening and closing blade 10 will move closer to and away from the center position of the chassis 9 or the paddle 8, thereby adjusting the size of the opening and closing opening of the control device. In this embodiment, the number of the arc-shaped guide slot 16 provided on the paddle 8, the strip-shaped guide slot 17 provided on the chassis 9, and the slide post 11 provided on the opening and closing blade 10 corresponds to each other, and preferably twelve are provided for each.

[0062] Furthermore, an annular boss is provided inside the housing 1, and a transverse through hole is provided outside along the circumferential surface direction corresponding to the annular boss. The chassis 9 is supported and arranged on the annular boss, and its chassis handle 18 extends out of the housing 1 through the transverse through hole of the housing 1. The size of the chassis handle 18 is adapted to the transverse through hole. The chassis handle 18 is moved in the transverse through hole of the housing 1, so that the chassis 9 is rotated on the annular boss, and the opening and closing blades of the regulating device are opened and closed. The design length of the transverse through hole on the housing 1 is based on the maximum and minimum opening and closing opening of the regulating device when the chassis handle 18 is moved.

[0063] In the embodiment of the present invention, an acid distributor is arranged above the regulating device, and the acid distributor inputs external acid into the bundled hollow membrane fibers 7 of the hollow fiber hydrophobic membrane 3 through the opening and closing port of the regulating device.

[0064] The specific working process of the device of the present invention is as follows: The ammonia-nitrogen wastewater to be treated enters the wastewater inlet chamber 4 from the ammonia-nitrogen wastewater inlet 19. The ammonium ions contained in the ammonia-nitrogen wastewater in the wastewater inlet chamber 4 enter the driving chamber 5 through the cation exchange membrane 2 under the action of concentration difference. At the same time, the external driving liquid enters the driving chamber 5 through the driving liquid inlet 21. The driving liquid is alkaline. The driving liquid in the driving chamber 5 reacts chemically with the ammonium ions to generate an ammonia aqueous solution. The ammonia aqueous solution decomposes into ammonia gas and water. Due to the difference in ammonia partial pressure between the driving chamber 5 and the recovery chamber 6, the ammonia gas generated in the driving chamber 5 enters the recovery chamber 6 through the hollow fiber hydrophobic membrane 3, contacts the bundle of hollow membrane filaments 7 regulated by the regulating device in the recovery chamber 6, and enters the bundle of hollow membrane filaments 7 participating in the acid liquid contact work. Finally, it reacts under the action of the acid liquid to generate liquid ammonium salt and is thus recovered.

[0065] Compared with the prior art, the present invention has the following advantages:

[0066] 1) Starting from membrane wetting, the present invention first proposes an innovative tubular dual-membrane ammonia-nitrogen removal and recovery device, forming a three-chamber two-membrane structure, which can better control the uniform distribution and flow of the liquid in the tube, reduce the thickness of the liquid film layer and prevent the accumulation of pollutants on the membrane surface. At the same time, it can also reduce the dead water area and flow dead angle, and reduce the risk of membrane wetting.

[0067] 2) Starting from membrane fouling, the present invention adopts a nested method with the cation exchange membrane on the outside and the hollow fiber hydrophobic membrane on the inside. The cation exchange membrane on the outside can act as a barrier to isolate anions and some high-valent metal ions, separating the sewage from the hydrophobic membrane to achieve the purpose of slowing down the fouling of the hydrophobic membrane; the cation exchange membrane on the outside can separate the alkali liquid from the wastewater, avoiding the interaction between impurities in the wastewater and the alkali, which is beneficial to subsequent treatment; compared with directly adjusting the pH of the feed waste liquid, after ammonia-nitrogen is enriched and concentrated, the utilization rate of the alkali can be improved, the cost can be saved, and the high mass transfer rate of ammonia gas can still be ensured.

[0068] 3) Starting from kinetics, compared with the existing coupled components of Donnan dialysis and osmotic distillation, the tubular dual-membrane ammonia-nitrogen removal and recovery device of the present invention can improve the problems of small flux, large pressure loss and reduced membrane process power of the traditional coupled components, and can achieve more efficient turbulent flow, which helps to improve the mass transfer efficiency and the flux size of the membrane. And the design of the integrated tubular membrane module does not require pipe fittings connection, which can enhance the hydrodynamic effect, achieve higher water flow velocity and pressure, improve the driving force of the membrane process, and can significantly improve the separation performance of the membrane for ammonia-nitrogen and extend the service life of the membrane.

[0069] 4) From the perspective of process applicability, the tubular dual-membrane ammonia nitrogen removal and recovery device of the present invention has a large membrane surface area to volume ratio, which can accommodate more membrane area in a module of the same volume, thereby reducing the accumulation concentration of pollutants on a single membrane area. The present invention has the advantages of high integration (loading) density, strong treatment capacity, small floor area, flexible series connection mode, simple operation, and strong adaptability to application sites. It can reduce pollution and blockage problems caused by the formation of local high-concentration areas, and is applicable to the process combination application of multiple ports in wastewater treatment plants. It has a wide range of applications and broad development prospects in the overall process of promoting the technological innovation of wastewater resource utilization.

[0070] 5) From the perspective of cleaning and maintenance, compared with traditional flat plate components, the tubular dual-membrane ammonia nitrogen removal and recovery device of the present invention allows liquid to flow uniformly and efficiently inside the tube, without dead corners, is not prone to fouling and blockage, the cleaning operation is simple, no special cleaning agents are required, and the cleaning and maintenance cost is low; the mechanical stability of the present invention is strong, and the membrane module is not easily damaged.

[0071] 6) From the perspective of product recovery, the tubular dual-membrane ammonia nitrogen removal and recovery device of the present invention can recover nitrogen in sewage through acid solution to obtain high-purity ammonium salt products. Compared with the existing recovery process, the economic benefit per ton of water can be increased by 3-6 times, and there is no secondary pollution. It belongs to an environmentally friendly component, which is in line with the concept of sustainable development and the principle of circular economy.

[0072] 7) The tubular dual-membrane ammonia nitrogen removal and recovery device of the present invention shows significant advantages in wastewater ammonia nitrogen recovery, including simple operation, environmental friendliness, high efficiency and low energy consumption, etc. In addition, the tubular component can be integrated with an electrochemical system to achieve the reduction of chemical reagent use and the improvement of ammonia nitrogen recovery efficiency. The tubular component is usually made of commercially available polyolefin materials (such as polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, etc.), and has good moisture resistance, thermal stability and chemical stability. In the future, the tubular membrane technology is expected to be further developed. By improving the membrane material, optimizing the system design and enhancing the energy efficiency, it can be widely applied in wastewater treatment and resource recovery, and contribute to the realization of sustainable nitrogen cycle and environmental protection.

[0073] In addition, in the existing technologies for treating ammonia nitrogen wastewater, either based on concentration difference driving (i.e., natural concentration difference driving) or based on electric driving, there is a lack of an ammonia nitrogen wastewater treatment device that effectively combines the two driving methods and has a reasonable structure. To solve this problem, in a preferred embodiment, an electric driving component is further included. The electric driving component includes an anode metal mesh 12 and a cathode metal mesh 13. The anode metal mesh 12 and the cathode metal mesh 13 are configured as tubular structures, and the anode metal mesh 12 is disposed between the housing 1 and the cation exchange membrane 2; the cathode metal mesh 13 is disposed between the cation exchange membrane 2 and the hollow fiber hydrophobic membrane 3; the anode metal mesh 12 is connected to the positive electrode of the power supply, and the cathode metal mesh 13 is connected to the negative electrode of the power supply. In the present invention, based on the design of the three-chamber two-membrane structure (or, called the tubular double-membrane structure) of the device of the present invention, the electric driving component can be easily and reasonably assembled into the coupled structure of Donnan dialysis and osmotic distillation without any opposite interference or conflict, which is unexpected according to the prior art. When the electric driving is operated and started, the overall device forms a structure of electro-dialysis / -Donnan dialysis composite driving and coupled with osmotic distillation, so as to be effectively applicable to the treatment of high-concentration ammonia nitrogen wastewater.

[0074] In this embodiment, when the anode metal mesh 12 and the cathode metal mesh 13 are energized and working, the wastewater inlet chamber 4 forms an anode chamber, and the driving chamber 5 forms a cathode chamber. In the anode chamber, an oxygen evolution reaction occurs on the anode metal mesh 12, water molecules lose electrons and are oxidized to generate oxygen and hydrogen ions. The chemical equation is as follows:

[0075] \left [ {2{H}_{2}O(l)\to {O}_{2}(g)+4{H}^{+}(aq)+4{e}^{-}} \right ]

[0076] In the cathode chamber, a hydrogen evolution reaction occurs on the cathode metal mesh 13, water molecules gain electrons and are reduced to generate hydrogen and hydroxide ions. The chemical equation is as follows:

[0077] \left [ {2{H}_{2}O(l)+2{e}^{-}\to {H}_{2}(g)+2O{H}^{-}(aq)} \right ] 。

[0078] In the present invention, first, the ammonia nitrogen wastewater enters the anode chamber, and the ammonium ions contained therein enter the cathode chamber through the cation exchange membrane 2 under the drive of the external electric field; then the ammonium ions combine with the hydroxide ions generated by the cathode metal mesh 13 to form free gaseous ammonia molecules. Due to the difference in ammonia partial pressure between the cathode chamber and the recovery chamber 6, the ammonia enters the recovery chamber 6; finally, the gaseous ammonia molecules combine with the hydrogen ions in the recovery chamber 6 to form ammonium ions, and thus are recovered in the form of liquid ammonium salt.

[0079] In the embodiment of the present invention, electro-driven and concentration-driven can be flexibly adjusted. When treating high-concentration ammonia-nitrogen wastewater, if the concentration-driven effect is not ideal, it can be switched to electro-driven for ammonia-nitrogen recovery.

[0080] Furthermore, the anode metal mesh 12 is a titanium mesh coated with Ir mixed metal oxide, and / or the cathode metal mesh 13 is a stainless steel diamond grid mesh.

[0081] The device of the present invention has the following advantages in recovering ammonia-nitrogen by electro-driven after being powered on:

[0082] 1) Higher ammonia mass transfer rate

[0083] After being powered on, the mechanism of electric field driving is used to enhance the mass transfer process of ammonia-nitrogen. By applying an electric field, ammonium ions (NH4 + ) in the system undergo directional migration under the action of the electric field force, which greatly accelerates the speed of ammonia-nitrogen ions (NH4 + ) passing through the cation exchange membrane (CEM). Therefore, the rapid migration of ions under the action of the electric field improves the removal rate of ammonia-nitrogen and the overall efficiency of the system.

[0084] 2) Zero chemical consumption in the driving chamber

[0085] After being powered on, a mechanism for removing ammonia-nitrogen with zero chemical consumption can be achieved in the driving chamber. When not powered on, in order to drive the Donnan dialysis process, salts and alkalis need to be added to the driving chamber. After being powered on, the system can generate OH - in the cathode chamber electrochemically. This process avoids the consumption of chemical reagents. The OH - generated by the cathode metal mesh directly reacts with NH4 + to generate gaseous ammonia, and then the effective removal and recovery of ammonia-nitrogen are achieved through the subsequent steps of the system. Therefore, the system has obvious advantages in reducing the consumption of chemical reagents and improving the environmental benefits after being powered on.

[0086] 3) Power-on can reduce the reverse diffusion of NH4 +

[0087] The free ammonia generated in the existing Donnan dialysis osmotic distillation (DDOD) system during the treatment process, because it is generated near the cation exchange membrane (CEM) and there is a certain distance between it and the hollow fiber hydrophobic membrane (GPM), results in the inability of NH4 + passing through the CEM to be quickly converted into free ammonia, thus accumulating on the left side of the CEM. When the accumulation reaches a certain level, a reverse diffusion phenomenon will occur, which not only reduces the removal efficiency of ammonia-nitrogen but also may cause secondary pollution. In contrast, after being powered on, due to the direct action of the electric field force, it can promote NH4 + to migrate to the GPM faster and react with the OH generated by the cathode metal mesh.- It rapidly combines to generate NH3. In addition, the integrated intensive device design of the system after power-on significantly shortens the distance between the electrode and the GPM. This compact configuration significantly accelerates the mass transfer process of NH3, effectively avoiding the problems of ammonia accumulation and reverse diffusion, thereby improving the removal efficiency and stability of the entire system. This design not only optimizes the operating conditions but also enhances the processing capacity of the system.

[0088] 4) Degradation of part of COD in the anodic reaction to alleviate membrane fouling

[0089] In the DDOD system, the organic matter in the waste liquid mainly has negatively charged functional groups, which tend to interact with the positively charged groups on the cation exchange membrane (CEM), resulting in a decrease in membrane flux and affecting the overall treatment efficiency. In contrast, the electric field force in the system after power-on can effectively attract these negatively charged organic matter molecules, causing them to move towards the anodic metal mesh, thus avoiding the unfavorable binding with the CEM and significantly reducing the risk of membrane fouling. In addition, the oxidation reaction occurring on the anodic metal mesh in the powered system and the strongly oxidizing substances generated can degrade part of the chemical oxygen demand (COD). This not only effectively avoids membrane fouling but also improves the biological / chemical oxygen demand ratio (B / C ratio) of the effluent and enhances the effect of subsequent biological treatment.

[0090] 5) Adjusting voltage and current, the device is flexible in operation and highly adaptable

[0091] By adjusting the voltage and current, the system can adapt to the changing working conditions requirements and optimize the removal and recovery efficiency of ammonia nitrogen. This adjustment ability not only enables the system to flexibly adjust the operating parameters according to the concentration change of ammonia nitrogen in the wastewater but also allows the operator to precisely control the ion migration during the reaction according to the specific treatment objectives and environmental conditions, thereby achieving the efficient removal of ammonia nitrogen. In addition, the adjustment of voltage and current also endows the system with the ability to cope with different water quality and water volume changes, enabling the system to maintain the best treatment performance under various environmental conditions.

[0092] Such as Figure 8As shown, in a preferred embodiment, the wastewater inlet chamber 4 is provided with a spiral water inlet corridor 14 for receiving the input of the ammonia nitrogen wastewater to be treated. The spiral water inlet corridor 14 is spirally wound from top to bottom along the outer side of the cation exchange membrane 2. The provided spiral water inlet corridor 14 extends the inflow path of the ammonia nitrogen wastewater to be treated, increases the contact time with the cation exchange membrane 2, and improves the mass transfer efficiency and deammoniation efficiency; moreover, the formed spiral flow field can enhance the turbulent flow, reduce the concentration polarization phenomenon occurring on the surface of the cation exchange membrane 2; and the spiral water inlet can also increase the tangential flow velocity of the water flow, has a scouring effect on the cation exchange membrane 2, and reduces the deposition of pollutants on the surface of the cation exchange membrane 2; in addition, the spiral water inlet corridor 14 can also make the ammonia nitrogen wastewater flow more evenly over the surface of the cation exchange membrane 2, reduce the formation of local high-concentration regions, thereby reducing the risk of the cation exchange membrane 2 being contaminated and extending the service life of the cation exchange membrane 2.

[0093] Among them, a smaller spiral angle can maintain the stability of the flow of the ammonia nitrogen wastewater, while a larger spiral angle can increase the tangential velocity of the fluid, thereby enhancing the shear force and realizing the scouring of the pollutants on the surface of the cation exchange membrane 2. Preferably, the spiral angle of the spiral water inlet corridor 14 is 15° - 25°; and the angle between the spiral water inlet corridor 14 and the cation exchange membrane 2 is 45°, which can form an impact force in the tangential direction, has a scouring effect on the cation exchange membrane 2, and avoids the cation exchange membrane 2 from being contaminated.

[0094] As Figure 1 And Figure 2 As shown, in a preferred embodiment, a mesh support member 15 is provided on the outer side and / or the inner side of the cation exchange membrane 2. The provided mesh support member 15 can evenly disperse the pressure impact caused by the inflow of the ammonia nitrogen wastewater to be treated on the cation exchange membrane 2, effectively avoiding the risk of damage to the surface of the cation exchange membrane 2 due to excessive local pressure; moreover, the geometric configuration of the mesh support member 15 reduces the pressure drop in the flow channel, reduces the energy consumption; and can also improve the additional mechanical strength, which helps to maintain the stability of the system in the face of fluid pressure fluctuations. Among them, the thickness of the mesh support member 15 is preferably 1 - 3 mm.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A tubular dual-membrane ammonia nitrogen removal and recovery device, characterized in that, Comprising: A housing (1) having a hollow inner cavity; A cation exchange membrane (2) which is of a tubular structure and is disposed in the hollow inner cavity of the housing (1); A hollow fiber hydrophobic membrane (3) which is of a tubular structure and is disposed in the inner cavity of the cation exchange membrane (2); A wastewater inlet chamber (4) is formed between the housing (1) and the cation exchange membrane (2); a driving chamber (5) is formed between the cation exchange membrane (2) and the hollow fiber hydrophobic membrane (3); a recovery chamber (6) is formed inside the hollow fiber hydrophobic membrane (3); Wherein, the wastewater inlet chamber (4) is configured to receive the input of the ammonia nitrogen wastewater to be treated, the driving chamber (5) is configured to receive the input of an external driving liquid, and the recovery chamber (6) is configured to receive the input of an external acid solution and output ammonium salts outward; The hollow fiber hydrophobic membrane (3) includes a plurality of closely arranged bundle-shaped hollow membrane filaments (7), and a regulating device capable of adjusting the opening degree of the acid solution inlet is provided corresponding to the acid solution inlet of the hollow fiber hydrophobic membrane (3), so that the number of membrane filaments participating in the acid solution contact work in all the bundle-shaped hollow membrane filaments (7) can be adjusted.

2. The tubular dual-membrane ammonia nitrogen removal and recovery device according to claim 1, characterized in that, The regulating device is configured to be able to determine the opening degree of the acid solution inlet of the hollow fiber hydrophobic membrane (3) based on the concentration of the ammonia nitrogen wastewater to be treated.

3. The tubular double-membrane ammonia nitrogen removal and recovery device according to claim 2, wherein, The regulating device includes a dial (8), a chassis (9) and a plurality of opening and closing blades (10). The dial (8) and the chassis (9) are respectively provided with sliding grooves. The sliding grooves of the dial (8) and the chassis (9) are at a certain angle in space. The opening and closing blades (10) are provided with sliding columns (11). The sliding columns (11) are positioned in the sliding grooves. The chassis (9) can be driven to rotate. The sliding columns (11) slide in the sliding grooves through the rotation of the chassis (9). By means of the repeated sliding of the sliding columns (11) in the sliding grooves, the opening and closing blades (10) approach and move away from the central position, thereby adjusting the opening and closing range of the regulating device.

4. The tubular dual-membrane ammonia nitrogen removal and recovery device according to claim 3, wherein, The number of the sliding grooves provided on the dial (8), the sliding grooves provided on the chassis (9) and the sliding columns (11) provided on the opening and closing blades (10) corresponds one by one.

5. The tubular dual-membrane ammonia nitrogen removal and recovery device according to claim 4, characterized in that A acid distributor is provided above the regulating device. The acid distributor inputs the external acid solution into the bundle-shaped hollow membrane filaments (7) of the hollow fiber hydrophobic membrane (3) through the opening of the regulating device.

6. The tubular dual-membrane ammonia nitrogen removal and recovery device according to any one of claims 1-5, characterized in that, It further includes an electric drive assembly, and the electric drive assembly includes: An anode metal mesh (12) which is of a tubular structure and is disposed between the housing (1) and the cation exchange membrane (2); A cathode metal mesh (13) which is of a tubular structure and is disposed between the cation exchange membrane (2) and the hollow fiber hydrophobic membrane (3); The anode metal mesh (12) is connected to the positive pole of the power supply, the cathode metal mesh (13) is connected to the negative pole of the power supply. When the anode metal mesh (12) and the cathode metal mesh (13) are energized to work, the wastewater inlet chamber (4) forms an anode chamber, and the driving chamber (5) can form a cathode chamber.

7. The tubular double-membrane ammonia nitrogen removal and recovery device according to claim 6, wherein, The anode metal mesh (12) is a titanium mesh coated with Ir mixed metal oxide, and / or, the cathode metal mesh (13) is a stainless steel diamond grid mesh.

8. The tubular double-membrane ammonia nitrogen removal and recovery device according to claim 6, characterized in that, The wastewater inlet chamber (4) is provided with a spiral water inlet corridor (14) for receiving the input of ammonia nitrogen wastewater to be treated, and the spiral water inlet corridor (14) is spirally wound from top to bottom along the outer side of the cation exchange membrane (2).

9. The tubular dual-membrane ammonia nitrogen removal and recovery device according to claim 8, wherein, The spiral angle of the spiral water inlet corridor (14) is 15° to 25°, and the angle between the spiral water inlet corridor (14) and the cation exchange membrane (2) is 45°.

10. The tubular double-membrane ammonia nitrogen removal and recovery device according to claim 6, characterized in that, A mesh support member (15) is provided on the outer side and / or the inner side of the cation exchange membrane (2).

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