Hollow fiber membrane contactor for treatment of nitrogen-containing wastewater

Abstract

The utility model provides a kind of hollow fiber membrane contactor for nitrogen-containing wastewater treatment, the cavity of membrane shell both ends is communicated by multiple membrane filaments, water distribution pipe is penetrated in the middle of membrane shell, first baffle is equipped in the middle of water distribution pipe and is cut off, and the outer circumferential circle of first baffle is close to the inner wall of membrane shell, multiple membrane filaments are evenly set along water distribution pipe spiral, still be equipped with multiple membranes, membrane is also spirally set, and the both ends of membrane are respectively connected with the both ends inside membrane shell. Ensure stable operation under the condition of complex wastewater composition, suitable for large-scale nitrogen-containing wastewater treatment.

Description

Technical Field

[0001] This utility model relates to the field of nitrogen-containing wastewater treatment, and in particular to a hollow fiber membrane contact device for nitrogen-containing wastewater treatment. Background Technology

[0002] The treatment of nitrogen-containing wastewater has always been a challenge in the field of environmental protection, especially the removal of ammonia nitrogen from wastewater. Traditional ammonia nitrogen treatment methods include biological nitrification and denitrification, chemical precipitation, and ion exchange, but these methods have problems such as low treatment efficiency, high cost, and complex operation.

[0003] In recent years, membrane technology has gradually attracted attention in wastewater treatment, especially hollow fiber membrane contactor technology. Due to its high mass transfer efficiency, simple operation, and low operating cost, it has shown broad application prospects. However, existing hollow fiber membrane contactors still have some shortcomings when treating nitrogen-containing wastewater, such as decreased mass transfer efficiency due to membrane fouling, insufficient durability of membrane materials, and poor adaptability to complex wastewater composition. Utility Model Content

[0004] The main purpose of this invention is to provide a hollow fiber membrane contact device for treating nitrogen-containing wastewater, which solves the problem of low mass transfer efficiency.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: A hollow fiber membrane contact device for treating nitrogen-containing wastewater, wherein the cavities at both ends of the membrane shell are connected by multiple membrane filaments, a water distribution pipe runs through the middle of the membrane shell, a first baffle is provided in the middle of the water distribution pipe for separation, and the outer circumference of the first baffle is close to the inner wall of the membrane shell, multiple membrane filaments are spirally and evenly arranged along the water distribution pipe, and multiple thin films are also provided, which are also spirally arranged, and the two ends of the thin films are respectively connected to the two ends inside the membrane shell.

[0006] In the preferred embodiment, the two ends of the water distribution pipe extend out of the membrane housing and are connected to the wastewater inlet and the clean water outlet, respectively.

[0007] In the preferred embodiment, the cavity at one end of the membrane housing near the purified water outlet is provided with an absorbent inlet, and the cavity at the other end is provided with an absorbent outlet.

[0008] In the preferred embodiment, a second baffle is provided on one side of the first baffle, and the second baffle is positioned in the direction of the wastewater inlet.

[0009] In the preferred embodiment, the diameter of the second baffle is smaller than the diameter of the first baffle.

[0010] In the preferred embodiment, the water distribution pipe is provided with multiple central distribution holes around its perimeter, and the central distribution holes are evenly distributed on the water distribution pipe in the radial direction. The diameter of the multiple central distribution holes increases from the water inlet end toward the first baffle.

[0011] In the preferred embodiment, the membrane fiber material is polytetrafluoroethylene with nanofibers. Modified PTFE with hydrophobic coating; The membrane fiber material has an ammonia / water selectivity coefficient >500 and a contact angle ≥120°.

[0012] In the preferred embodiment, the angle of inclination of the membrane fiber spiral is 30°-60°.

[0013] In the preferred embodiment, the outer diameter of the membrane fiber is 500~600μm and the inner diameter is 200~300μm.

[0014] In the preferred embodiment, the film is a non-porous film, and the film material is polyethylene, polypropylene, polyvinyl chloride, or polyvinylidene fluoride.

[0015] This invention provides a hollow fiber membrane contact device for treating nitrogen-containing wastewater. This hollow fiber membrane contactor for nitrogen-containing wastewater treatment achieves highly efficient nitrogen removal. It uses modified PTFE hollow fiber membrane filaments with an ammonia / water selectivity coefficient >500 and a contact angle ≥120°. Combined with an interlaced arrangement, baffles, and spiral flow guide design, the effective contact area is increased by more than 20%, creating turbulence and solving the problem of low mass transfer efficiency. The ammonia nitrogen removal rate can reach 98.4%, and the ammonia nitrogen concentration in the treated wastewater is ≤45ppm, meeting environmental emission standards. It has strong anti-fouling capabilities; the smooth surface of the modified PTFE membrane filaments makes it difficult for pollutants to adhere. During the ammonia nitrogen removal process, a 15%-20% ammonium sulfate solution is generated, which can be directly recycled as fertilizer, possessing certain economic value. It ensures stable operation under complex wastewater composition conditions and is suitable for large-scale nitrogen-containing wastewater treatment. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is the main view structural diagram of this utility model; Figure 2 This is a front view structural diagram of the membrane filament distribution of this utility model; Figure 3 This is a front view of the spiral distribution structure of the membrane filaments of this utility model; Figure 4 This is a side view of the spiral distribution structure of the membrane filaments of this utility model.

[0017] In the diagram: membrane shell 1; membrane fiber 2; water distribution pipe 3; wastewater inlet 301; clean water outlet 302; central distribution hole 303; first baffle 4; second baffle 5; absorbent inlet 6; absorbent outlet 7; membrane 8. Detailed Implementation

[0018] Example 1 like Figure 1-4 As shown, a hollow fiber membrane contact device for treating nitrogen-containing wastewater has a membrane shell 1 with cavities at both ends connected by multiple membrane filaments 2. A water distribution pipe 3 runs through the middle of the membrane shell 1. A first baffle 4 is provided in the middle of the water distribution pipe 3 for partitioning, and the outer circumference of the first baffle 4 is close to the inner wall of the membrane shell 1. Multiple membrane filaments 2 are spirally and evenly arranged along the water distribution pipe 3. Multiple thin films 8 are also provided, which are also spirally arranged, and the two ends of the thin films 8 are respectively connected to the two ends inside the membrane shell 1.

[0019] The two ends of the water distribution pipe 3 extend out of the end of the membrane shell 1 and are connected to the wastewater inlet 301 and the clean water outlet 302 respectively.

[0020] Nitrogenous wastewater is introduced into an equalization tank. The temperature is controlled at 20-40℃ using a temperature control device, and the pH is adjusted to 10-12 using a pH control device to reduce the concentration of ammonium ions in the wastewater. Converted into gaseous ammonia .

[0021] Pretreated nitrogen-containing wastewater enters through wastewater inlet 301 of distribution pipe 3 and flows through the outer flow channel of the membrane filaments formed on the outside of distribution pipe 3 inside membrane shell 1; simultaneously, sulfuric acid is... As an absorbent, it is introduced into the inner flow channel of the membrane filament, which is composed of the cavities at both ends of the membrane shell 1 and multiple membrane filaments 2.

[0022] In the outer channel of the membrane fiber, gaseous ammonia (NH3) permeates through the selectively permeable membrane fiber 2 into the inner channel, where it reacts with the sulfuric acid absorbent to form ammonium sulfate. Solution.

[0023] The ammonia-free water after removing ammonia nitrogen from the outer channel of the membrane fiber is discharged through the clean water outlet 302 of the water distribution pipe 3; the ammonium sulfate solution generated in the inner channel of the membrane fiber is collected through the absorbent outlet 7 for further treatment or recycling.

[0024] The cleaning system is activated every 8-12 hours to perform reverse pulse flushing of the membrane module at a pressure of 0.2 MPa for 5 minutes. The cleaning agent is then pumped from the independent storage tank into the inner flow channel of the membrane fibers through pipelines to restore the mass transfer performance of the membrane fibers.

[0025] The modified PTFE membrane fibers have a smooth surface and strong antifouling properties. When combined with an automated reverse pulse cleaning system, it can extend the service life of the membrane module and reduce operating costs. The generated ammonium sulfate solution has a concentration of 15%-20%, which can be recycled as fertilizer, realizing resource recovery. The spiral arrangement of the membrane fibers 2, membrane 8, and first baffle 4 optimizes the hydrodynamic performance, reduces membrane fiber vibration, and ensures stable operation of the system under complex wastewater composition conditions. It also integrates temperature and pH adjustment devices and an automated cleaning system, making it easy to operate and suitable for large-scale treatment.

[0026] In the preferred embodiment, the cavity at one end of the membrane housing 1 near the purified water outlet 302 is provided with an absorbent inlet 6, and the cavity at the other end is provided with an absorbent outlet 7.

[0027] The adjusted wastewater is pumped from the wastewater inlet 301 of the water distribution pipe 3 into the outer channel of the membrane filaments inside the membrane housing 1. At the same time, sulfuric acid is pumped from the absorbent inlet 6 of the cavity near the clean water outlet 302 at one end of the membrane housing 1 into the inner channel of the membrane filaments, which is composed of cavities at both ends of the membrane housing 1 and multiple membrane filaments 2. The gaseous ammonia converted by pH and temperature adjustment in the outer channel of the membrane filaments permeates through the membrane filaments 2, which are spirally and evenly arranged along the water distribution pipe 3, into the inner channel and reacts with sulfuric acid to generate ammonium sulfate solution. The ammonium sulfate solution is discharged from the absorbent outlet 7 of the cavity at the other end of the membrane housing 1 and collected through the water collection pipe for subsequent treatment or recycling. The ammonia-free water after ammonia nitrogen removal in the outer channel of the membrane filaments is discharged through the clean water outlet 302 of the water distribution pipe 3. The first baffle 4 intersects with the inner wall of the membrane shell 1 and the membrane fibers to form a tortuous flow channel, which optimizes the fluid path, enhances the turbulence effect, avoids wastewater short-circuiting, and enables the ammonia nitrogen removal rate to reach 98.4%. The ammonia nitrogen concentration of the treated effluent is ≤45ppm, which meets the environmental protection emission standards. In the preferred embodiment, a second baffle 5 is provided on one side of the first baffle 4, and the second baffle 5 is positioned in the direction of the wastewater inlet 301. The diameter of the second baffle 5 is smaller than the diameter of the first baffle 4.

[0028] Nitrogenous wastewater is introduced into an equalization tank, where the temperature is adjusted to 20-40℃ and the pH is adjusted to 10-12 by a temperature control device, converting ammonium ions into gaseous ammonia. The regulated wastewater enters through the wastewater inlet 301 of the distribution pipe 3 and flows sequentially through the areas where the second baffle 5 and the first baffle 4 are located. The diameter of the second baffle 5 is smaller than that of the first baffle 4. The two work together to optimize the fluid dynamics performance. With multiple membrane fibers 2 spirally and evenly arranged along the distribution pipe 3, the membrane fibers are stabilized, reducing vibration. At the same time, they interweave with the inner wall of the membrane shell 1 and the membrane fibers to form a tortuous flow channel, enhancing the turbulence effect.

[0029] Wastewater flows in the outer channel of the membrane filament formed by the water distribution pipe 3 inside the membrane shell 1. Gaseous ammonia permeates through the membrane filament 2 to the inner channel of the membrane filament formed by the cavity at both ends of the membrane shell 1 connected to the membrane filament 2. It reacts with sulfuric acid fed from the absorbent inlet 6 to generate ammonium sulfate solution. The ammonium sulfate solution is discharged from the absorbent outlet 7 and collected through the water collection pipe. Ammonia-free water is discharged from the clean water outlet 302.

[0030] In this scheme, the second baffle 5 works in conjunction with the first baffle 4 to further optimize the fluid path, avoid wastewater short-circuiting, and improve mass transfer efficiency, achieving an ammonia nitrogen removal rate of 98.4% and an effluent ammonia nitrogen level of ≤45ppm. The membrane fibers 2 with a stable spiral arrangement reduce vibration caused by water flow impact. Combined with the antifouling properties of the modified PTFE membrane fibers and an automatic cleaning system, this extends membrane life and reduces costs. The generated 15%-20% ammonium sulfate solution can be recycled as fertilizer, realizing resource utilization. Furthermore, the overall structure is suitable for large-scale treatment and operates stably and reliably.

[0031] In the preferred embodiment, the water distribution pipe 3 is provided with multiple central distribution holes 303 around its perimeter, and the central distribution holes 303 are evenly arranged on the water distribution pipe 3 in the radial direction; The diameter of the multiple central distribution holes 303 increases from the water inlet end toward the first baffle 4.

[0032] The gradually changing pore size design of the central distribution hole 303 ensures uniform distribution of wastewater in the outer flow channel of the membrane fibers, improving mass transfer efficiency. Combined with the action of the second baffle 5 and the first baffle 4, it further optimizes the fluid dynamics performance, stabilizes the spirally arranged membrane fibers 2, reduces vibration, enhances turbulence, and achieves an ammonia nitrogen removal rate of 98.4%, with effluent ammonia nitrogen ≤45ppm. Uniform effluent discharge reduces local pollution. Combined with the antifouling properties of the modified PTFE membrane fibers and the automatic cleaning system, it extends membrane life and reduces costs. The generated 15%-20% ammonium sulfate solution can be recycled. The overall structure is suitable for large-scale treatment and operates stably and efficiently.

[0033] In the preferred embodiment, the material of membrane fiber 2 is polytetrafluoroethylene plus nanofibers. Modified PTFE with hydrophobic coating; The material of membrane fiber 2 has an ammonia / water selectivity coefficient >500 and a contact angle ≥120°.

[0034] In the preferred embodiment, the angle of inclination of the membrane fiber 2 spiral is 30°-60°.

[0035] The membrane fibers are arranged in a 30°-60° spiral angle, combined with baffles and spiral flow guiding design, which increases the effective contact area by more than 20%, forming turbulence and providing good structural stability. Existing technologies mostly use parallel arrangement, with a fixed mass transfer area, which easily forms dead zones, and the membrane fibers are easily shaken by water flow impact.

[0036] In the preferred embodiment, the outer diameter of the membrane fiber 2 is 500~600μm and the inner diameter is 200~300μm.

[0037] In the preferred embodiment, the film 8 is a non-porous film, and the material of the film 8 is polyethylene, polypropylene, polyvinyl chloride, or polyvinylidene fluoride.

[0038] Using polytetrafluoroethylene plus nano Modified PTFE with hydrophobic coating has an ammonia / water selectivity coefficient >500, a contact angle ≥120°, a smooth surface, and strong antifouling properties. Existing technologies mostly use ordinary polypropylene or polyvinylidene fluoride, which have a selectivity coefficient <200, a contact angle of 90°-110°, and are prone to adsorbing organic matter, leading to membrane fouling.

[0039] With the cooperation of the second baffle 5, which has a diameter smaller than the first baffle 4 and is located in the direction of the wastewater inlet 301, and the first baffle 4, multiple membrane filaments 2, which are uniformly arranged at a spiral tilt angle of 30°-60° along the inner wall of the membrane shell 1 and along the water distribution pipe 3, and a non-porous membrane 8 made of polyethylene, polypropylene, polyvinyl chloride or polyvinylidene fluoride, are spirally arranged to form a tortuous flow channel.

[0040] Example 2 Further explanation in conjunction with Example 1, such as Figure 1-4 The structure shown illustrates a nitrogen-containing wastewater treatment project in a factory that utilizes the aforementioned hollow fiber membrane contactor. The membrane housing 1 of the contactor has cavities at both ends connected by multiple membrane filaments 2. The membrane filaments 2 are made of polytetrafluoroethylene with nanofibers. The modified PTFE with a hydrophobic coating has an ammonia / water selectivity coefficient >500 and a contact angle ≥120°. It is uniformly arranged along the water distribution pipe 3 with a spiral tilt angle of 30°-60°, with an outer diameter of 500~600μm and an inner diameter of 200~300μm. The water distribution pipe 3, which runs through the middle of the membrane shell 1, has multiple radially uniformly arranged central distribution holes 303 around its perimeter. The diameter of the central distribution holes 303 increases from the water inlet end to the first baffle 4. The two ends of the water distribution pipe 3 extend out of the membrane shell 1 and are connected to the wastewater inlet 301 and the clean water outlet 302, respectively. The first baffle 4 is fixed to the inner wall of the membrane shell, and a second baffle 5 with a smaller diameter than the first baffle 4 is provided on one side in the direction of the wastewater inlet 301. The membrane shell 1 is also provided with a spirally arranged non-porous membrane 8 made of polyethylene, with both ends connected to the two ends inside the membrane shell 1. The cavity near the clean water outlet 302 at one end of the membrane shell 1 is provided with an absorbent inlet 6, and the cavity at the other end is provided with an absorbent outlet 7.

[0041] During treatment, the nitrogen-containing wastewater (ammonia nitrogen concentration 3000 mg / L) from the factory is introduced into an equalization tank. The wastewater temperature is adjusted to 25°C using a temperature control device, and the pH of the wastewater is adjusted using a pH control device. The value is adjusted to 11, converting ammonium ions in the wastewater into gaseous ammonia. The adjusted wastewater is pumped into the wastewater inlet 301 of the distribution pipe 3 and evenly distributed through the central distribution hole 303 to the outer flow channel of the membrane filaments formed by the distribution pipe 3 inside the membrane housing 1. Under the combined action of the second baffle 5 and the first baffle 4, it forms a tortuous flow channel with the inner wall of the membrane housing 1, the membrane filaments 2, and the membrane 8, enhancing the turbulence effect. At the same time, sulfuric acid is sent from the absorbent inlet 6 into the inner flow channel of the membrane filaments, which is formed by the cavities at both ends of the membrane housing 1 and the membrane filaments 2. The gaseous ammonia in the outer flow channel of the membrane filaments permeates through the membrane filaments 2 into the inner flow channel and reacts with sulfuric acid to generate ammonium sulfate solution. The ammonium sulfate solution is discharged through the absorbent outlet 7 and collected by the water collection pipe. The ammonia-free water after removing ammonia nitrogen in the outer flow channel of the membrane filaments is discharged through the clean water outlet 302. The cleaning system is started every 10 hours, and the cleaning agent is pumped from the independent storage tank into the inner flow channel of the membrane filaments through the pipeline for reverse pulse flushing (pressure 0.2MPa, time 5 minutes). (minutes), to restore the mass transfer performance of membrane fiber 2.

[0042] After treatment, the ammonia nitrogen concentration in the wastewater was reduced to below 45 mg / L, with an ammonia nitrogen removal rate of 98.5%. The concentration of the by-product ammonium sulfate solution was 18%, which can be recycled as fertilizer.

[0043] The nitrogen-containing wastewater treatment capacity is: When the influent ammonia nitrogen concentration is 2828 mg / L, chloride concentration is 6678 mg / L, COD is 481 mg / L, and pH is 10.38, after treatment, the effluent ammonia nitrogen concentration is ≤45 ppm, pH is 6-9, the ammonia nitrogen removal rate reaches 98.4%, and the concentration of the generated ammonium sulfate solution is 15%-20%.

[0044] The above embodiments are merely preferred technical solutions of this utility model and should not be considered as limitations on this utility model. The protection scope of this utility model should be the technical solution described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the protection scope of this utility model.

Claims

1. A hollow fiber membrane contact device for treating nitrogen-containing wastewater, characterized in that: The cavities at both ends of the membrane shell (1) are connected by multiple membrane filaments (2). A water distribution pipe (3) runs through the middle of the membrane shell (1). A first baffle (4) is provided in the middle of the water distribution pipe (3) for separation. The outer circumference of the first baffle (4) is close to the inner wall of the membrane shell (1). Multiple membrane filaments (2) are spirally and evenly arranged along the water distribution pipe (3). Multiple thin films (8) are also provided. The thin films (8) are also spirally arranged. The two ends of the thin films (8) are respectively connected to the two ends inside the membrane shell (1).

2. The hollow fiber membrane contact device for treating nitrogen-containing wastewater according to claim 1, characterized in that: The two ends of the water distribution pipe (3) extend out of the end of the membrane shell (1) and are connected to the wastewater inlet (301) and the clean water outlet (302) respectively.

3. The hollow fiber membrane contact device for treating nitrogen-containing wastewater according to claim 2, characterized in that: The cavity at one end of the membrane housing (1) near the water outlet (302) is provided with an absorbent inlet (6), and the cavity at the other end is provided with an absorbent outlet (7).

4. The hollow fiber membrane contact device for treating nitrogen-containing wastewater according to claim 1, characterized in that: A second baffle (5) is provided on one side of the first baffle (4), and the second baffle (5) is located in the direction of the wastewater inlet (301).

5. The hollow fiber membrane contact device for treating nitrogen-containing wastewater according to claim 4, characterized in that: The diameter of the second baffle (5) is smaller than the diameter of the first baffle (4).

6. The hollow fiber membrane contact device for treating nitrogen-containing wastewater according to claim 1, characterized in that: The water distribution pipe (3) is provided with multiple central distribution holes (303) around its perimeter. The central distribution holes (303) are evenly arranged on the water distribution pipe (3) in the radial direction. The diameter of the multiple central distribution holes (303) increases from the water inlet end toward the first baffle (4).

7. The hollow fiber membrane contact device for treating nitrogen-containing wastewater according to claim 1, characterized in that: The material of the membrane fiber (2) is modified PTFE with a nano-SiO2 hydrophobic coating; The material of the membrane fiber (2) has an ammonia / water selectivity coefficient > 500 and a contact angle ≥ 120°.

8. The hollow fiber membrane contact device for treating nitrogen-containing wastewater according to claim 1, characterized in that: The angle of inclination of the membrane fiber (2) spiral is 30°-60°.

9. The hollow fiber membrane contact device for treating nitrogen-containing wastewater according to claim 1, characterized in that: The outer diameter of the membrane fiber (2) is 500~600μm and the inner diameter is 200~300μm.

10. A hollow fiber membrane contact device for treating nitrogen-containing wastewater according to claim 1, characterized in that: The film (8) is a non-porous film, and the material of the film (8) is polyethylene, polypropylene, polyvinyl chloride, and polyvinylidene fluoride.

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