A membrane method for removing ammonia nitrogen

Abstract

This invention discloses a membrane-based method for removing ammonia nitrogen, relating to the field of ammonia nitrogen wastewater treatment technology. The method involves first heat-exchanging and filtering the ammonia nitrogen wastewater, adjusting the pH to 11-14, and controlling the temperature at 30-45°C before feeding it into the shell side of a hydrophobic ammonia removal membrane. Then, acetic acid-containing wastewater from an acrylic acid plant is used as the absorbent, pumped into the tube side of the ammonia removal membrane via a circulation pump, forming a gas-liquid mass transfer system across the membrane with the shell-side wastewater. Ammonium ions in the wastewater are converted into gaseous ammonia at high pH and temperature, passing through the hydrophobic membrane pores into the tube side, where they are absorbed by the acrylic acid wastewater to generate acetic acid. The wastewater after ammonia nitrogen removal meets discharge standards, and the absorbent is recycled. This invention completely eliminates the use of sulfuric acid at the source by using acetic acid-containing wastewater from an acrylic acid plant instead of dilute sulfuric acid as the membrane-based ammonia removal absorbent, while simultaneously achieving resource utilization of acrylic acid wastewater. This eliminates the risks associated with the use, storage, and transportation of sulfuric acid, as well as the risks of corrosion, leakage, and control associated with sulfuric acid.

Description

Technical Field

[0001] This invention belongs to the field of ammonia nitrogen wastewater treatment technology, specifically relating to a membrane method for removing ammonia nitrogen. Background Technology

[0002] Currently, the mainstream treatment method for industrial ammonia nitrogen wastewater is membrane deammoniation technology. This technology generally uses dilute sulfuric acid as the absorbent and separates the ammonia-containing wastewater from the acid liquid through a hydrophobic microporous membrane. The ammonia gas is driven to diffuse to the acid side by the ammonia pressure difference on both sides of the membrane and reacts with sulfuric acid to generate ammonium sulfate, thereby achieving the removal and recovery of ammonia nitrogen.

[0003] However, since sulfuric acid is a highly corrosive and hazardous chemical and is a controlled precursor for narcotics, its storage, transportation, and application pose safety hazards to equipment, personnel, and the environment. Daily management processes are complex and compliance costs are high. Summary of the Invention

[0004] The purpose of this invention is to provide a membrane method for removing ammonia nitrogen, which directly replaces traditional dilute sulfuric acid with acrylic acid wastewater, eliminating the need for sulfuric acid addition and thus removing the risks associated with the use, storage, and transportation of sulfuric acid from the source, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A membrane-based method for removing ammonia nitrogen, using a membrane-based ammonia nitrogen removal system containing an ammonia removal membrane, includes the following steps:

[0007] S1. After heat exchange and filtration, the ammonia nitrogen wastewater is adjusted to pH 11-14 and the temperature is controlled at 30-45℃ before being fed into the shell side of the hydrophobic ammonia removal membrane.

[0008] S2. Using acetic acid-containing wastewater from the acrylic acid unit as the absorbent, it is pumped into the tube side of the deammoniation membrane via a circulating pump to form a gas-liquid mass transfer system on both sides of the membrane with the shell side wastewater of the deammoniation membrane.

[0009] S3. Ammonium ions in wastewater are converted into gaseous ammonia at high pH and temperature, which enters the tube side through hydrophobic membrane pores and is absorbed by acrylic acid wastewater to generate acetic acid.

[0010] S4. Wastewater after ammonia nitrogen removal meets discharge standards. The absorbent is recycled. When the pH of the absorbent is greater than 5, partial replacement is performed. The resulting ammonium acetate solution is utilized as a resource.

[0011] Preferably, the membrane-based ammonia nitrogen removal system includes a first plate heat exchanger for exchanging heat with ammonia nitrogen wastewater. The outlet of the first plate heat exchanger is connected to an ammonia nitrogen wastewater raw water tank. The outlet of the ammonia nitrogen wastewater raw water tank is connected to a security filter via a raw water pump. The outlet of the security filter is connected to a second plate heat exchanger. The outlet of the second plate heat exchanger is connected to an ammonia removal membrane. One end of the ammonia removal membrane is connected to an acrylic acid wastewater circulating tank for recycling the absorbent. The inlet of the acrylic acid wastewater circulating tank is connected to an acrylic acid raw water tank via an acrylic acid transfer pump. The outlet of the acrylic acid wastewater circulating tank is connected to an ammonium acetate filter and an ammonium acetate tank via a circulating pump. The outlet of the ammonium acetate filter is connected to the inlet of the ammonia removal membrane for circulating the absorbent into the ammonia removal membrane. The ammonia removal membrane is equipped with a transfer pipe for returning qualified permeate to the first plate heat exchanger.

[0012] Preferably, the deammoniation membrane is a PTFE hydrophobic hollow fiber membrane, with the membrane fibers woven into a cloth and wound into a column and inserted into the membrane shell.

[0013] Preferably, two ammonia removal membranes are provided, connected in series, and the flux of the ammonia removal membranes is 10m³ / s. 3 / h.

[0014] Preferably, three deammoniation membranes are provided, connected in series, and the flux of the deammoniation membranes is 10m³ / s. 3 / h.

[0015] Preferably, in step S1, the ammonia nitrogen wastewater after heat exchange and filtration is adjusted to pH 11-14 using a 30% sodium hydroxide solution, with the sodium hydroxide solution added at the front end of the security filter.

[0016] Preferably, in step S2, the acetic acid-containing wastewater is filtered through an ammonium acetate filter and then circulated into the ammonia removal membrane tube. When the pH of the acrylic acid wastewater absorbent is greater than 5, partial replacement is performed, and the discharged ammonium acetate solution is used as an additive for electroplating electrolyte, an electroplating complexing agent, or a nitrogen nutrient for wastewater treatment plants.

[0017] Preferably, the outer side of the deammoniation membrane is the shell side, through which ammonia nitrogen wastewater is introduced; the inner side of the membrane filaments is the tube side, through which acrylic acid wastewater absorption liquid is introduced.

[0018] Preferably, the first plate heat exchanger uses countercurrent heat exchange between ammonia nitrogen wastewater and qualified product water, and the temperature of the ammonia nitrogen wastewater after heat exchange is 15-20℃. The second plate heat exchanger uses heat exchange between ammonia nitrogen wastewater and steam, with a steam rate of 10-20m / s and the wastewater temperature controlled at 30-45℃.

[0019] Preferably, the ammonium acetate tank is connected to a discharge pump for discharging ammonium acetate, and the wastewater discharged by the discharge pump is either directly discharged or enters a subsequent treatment system.

[0020] The membrane-based ammonia nitrogen removal method proposed in this invention has the following advantages compared with existing technologies:

[0021] 1. This invention completely eliminates the use of sulfuric acid from the source by using acetic acid-containing wastewater generated by an acrylic acid plant as the membrane deammoniation absorption liquid, while realizing the resource utilization of acrylic acid wastewater. It also eliminates the risks of sulfuric acid use, storage, and transportation, as well as the risks of sulfuric acid corrosion, leakage, and control. The process operation is safer and there is no burden of hazardous chemical management.

[0022] 2. This invention uses acrylic acid production wastewater as the absorbent, which saves on the costs of acrylic acid wastewater treatment and discharge, as well as the costs of purchasing, storing, and adding sulfuric acid, thus achieving double cost reduction.

[0023] 3. The acetic acid in the acrylic acid wastewater of this invention can efficiently absorb gaseous ammonia, and the ammonia nitrogen removal effect is no less than that of traditional sulfuric acid absorption liquid, ensuring that the effluent meets the standards stably;

[0024] 4. The absorption product of this invention is ammonium acetate, which can be directly used as an additive for electroplating electrolyte, an electroplating complexing agent, and a nitrogen nutrient for sewage treatment plants. It has a wider range of resource utilization and retains the advantages of the original membrane deammoniation method, such as normal temperature and pressure, low energy consumption, and no ammonia gas emission. It can directly replace the absorption liquid without modifying the main equipment. Attached Figure Description

[0025] Figure 1 This is a block diagram of the membrane-based ammonia nitrogen removal system of the present invention;

[0026] Figure 2 This is a flowchart of the present invention.

[0027] In the diagram: 1. First plate heat exchanger; 2. Ammonia nitrogen wastewater raw water tank; 3. Raw water pump; 4. Security filter; 5. Second plate filter; 6. Ammonia removal membrane; 7. Acrylic acid wastewater circulating water tank; 8. Acrylic acid raw water tank; 9. Acrylic acid transfer pump; 10. Circulation pump; 11. Ammonium acetate filter; 12. Ammonium acetate tank; 13. Discharge pump. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] This invention provides, for example Figure 1-2 The illustrated method for removing ammonia nitrogen using a membrane system comprising an ammonia nitrogen removal membrane 6 includes a first plate heat exchanger 1 for exchanging heat with ammonia nitrogen wastewater. The outlet of the first plate heat exchanger 1 is connected to an ammonia nitrogen wastewater raw water tank 2. The outlet of the ammonia nitrogen wastewater raw water tank 2 is connected to a security filter 4 via a raw water pump 3. The outlet of the security filter 4 is connected to a second plate heat exchanger 5. The outlet of the second plate heat exchanger 5 is connected to the ammonia nitrogen removal membrane 6. One end of the ammonia nitrogen removal membrane 6 is connected to a... The acrylic wastewater circulating tank 7 is used for recycling the absorbent. The inlet of the acrylic wastewater circulating tank 7 is connected to the acrylic raw water tank 8 through the acrylic transfer pump 9. The outlet of the acrylic wastewater circulating tank 7 is connected to the ammonium acetate filter 11 and the ammonium acetate tank 12 through the circulating pump 10. The outlet of the ammonium acetate filter 11 is connected to the inlet of the deammoniation membrane 6 for circulating the absorbent into the deammoniation membrane 6. The deammoniation membrane 6 is provided with a transmission pipe for returning qualified product water to the first plate heat exchanger 1.

[0031] The first plate heat exchanger 1 uses countercurrent heat exchange between ammonia nitrogen wastewater and qualified product water. After heat exchange, the temperature of the ammonia nitrogen wastewater is 15-20℃. The first plate heat exchanger 1 is a high-efficiency heat exchange device. Its core principle is to transfer heat between two fluids with different temperatures by means of the thermal conductivity of the metal plates. The ammonia nitrogen wastewater and qualified product water enter from the upper and lower manifolds of the device, respectively, and flow countercurrently through the flow channels between the plates. Due to the high thermal conductivity of the plates, the heat of the hot fluid is transferred to the cold fluid through the plates, thereby achieving cooling or heating.

[0032] The second plate heat exchanger 5 uses ammonia nitrogen wastewater and steam for heat exchange, with a steam rate of 10-20 m / s and the wastewater temperature controlled at 30-45℃;

[0033] The filtration principle of the security filter 4 is that after the wastewater is pressurized, it passes through the filter element pores, and the suspended particles, colloids, rust and other impurities in the water are blocked by the filter element pores, reducing the fouling of the downstream ammonia removal membrane 6.

[0034] The ammonium acetate tank 12 is connected to a discharge pump 13 for discharging ammonium acetate. The wastewater discharged by the discharge pump 13 is directly discharged or enters the subsequent treatment system, realizing continuous replacement and resource output. The system is free from blockage and accumulation, and operates stably.

[0035] Ammonia nitrogen removal via a membrane system includes the following steps:

[0036] S1. After heat exchange and filtration, the ammonia nitrogen wastewater is adjusted to pH 11-14 and the temperature is controlled at 30-45℃ before being fed into the shell side of the hydrophobic ammonia removal membrane 6. The ammonia nitrogen wastewater after heat exchange and filtration is adjusted to pH 11-14 using a 30% sodium hydroxide solution. The sodium hydroxide solution is added at the front end of the security filter 4. The alkali solution is fully mixed with the wastewater to ensure that NH4+ is completely converted into NH3, thereby improving the ammonia removal efficiency. Furthermore, the pre-addition of alkali does not contaminate the membrane module.

[0037] S2. The acetic acid-containing wastewater generated by the acrylic acid unit is used as the absorbent and is sent to the tube side of the deammoniation membrane 6 by the circulating pump 10 to form a gas-liquid mass transfer system on both sides of the membrane with the shell side wastewater of the deammoniation membrane 6.

[0038] The acetic acid-containing wastewater is filtered by ammonium acetate filter 11 and then circulated into the deammonium removal membrane 6. When the pH of the acrylic acid wastewater absorbent is greater than 5, partial replacement is performed. The discharged ammonium acetate solution is used as an additive for electroplating electrolyte, an electroplating complexing agent, or a nitrogen nutrient for wastewater treatment plants. The recycling reduces the consumption of absorbent, and the resource-based products have high added value and no secondary waste is generated.

[0039] The ammonia removal membrane 6 is a PTFE hydrophobic hollow fiber membrane. The membrane fibers are woven into a cloth and wound into a column and installed inside the membrane shell. The outer side of the membrane fibers of the ammonia removal membrane 6 is the shell side, through which ammonia nitrogen wastewater is introduced; the inner side of the membrane fibers is the tube side, through which acrylic acid wastewater absorbent is introduced, forming a stable gas-liquid interface. NH3 is absorbed through directional diffusion, resulting in high mass transfer efficiency and no cross-contamination. The PTFE material is air-permeable but water-permeable, preventing wastewater from mixing with other liquids. The woven structure increases the mass transfer area, fixes the membrane fibers to prevent fiber breakage, and ensures long-term stable operation of the system.

[0040] S3. Ammonium ions in wastewater are converted into gaseous ammonia at high pH and temperature, which enters the tube side through hydrophobic membrane pores and is absorbed by acrylic acid wastewater to generate acetic acid.

[0041] S4. Wastewater after ammonia nitrogen removal meets discharge standards. The absorbent is recycled. When the pH of the absorbent is greater than 5, partial replacement is performed. The resulting ammonium acetate solution is utilized as a resource.

[0042] Specifically, the ammonia nitrogen wastewater undergoes heat exchange with the qualified product water discharge through the first plate heat exchanger 1. After heat exchange, the ammonia nitrogen wastewater reaches a temperature of 15-20℃ and then enters the ammonia nitrogen wastewater raw water tank 2. The wastewater transfer rate is 1-2 m / s. The ammonia nitrogen wastewater then enters the pleated filter cartridge security filter 4 through the raw water pump 3 for filtration. The filter cartridge has a filter precision of 5μm. This security filter 4 is set in front of the ammonia removal membrane 6 as a pre-filtration. Afterward, it passes through the second plate heat exchanger and exchanges heat with steam at a steam rate of 10-20 m / s. The wastewater temperature is controlled at 30-45℃, and then enters the outer side of the membrane fibers of the ammonia removal membrane 6. At the same time, a 30% sodium hydroxide solution is added before the security filter 4 to mix with the ammonia nitrogen wastewater and adjust the pH to 11. -14 enters the membrane together for ammonia nitrogen separation; simultaneously, acrylic acid wastewater in the acrylic acid wastewater circulation tank is pumped by acrylic acid wastewater circulation pump 10 through the ammonium acetate filter (the main component of acrylic acid wastewater is acetic acid, which absorbs ammonia nitrogen to generate ammonium acetate) and enters the inner side of the deammoniation membrane 6 as the absorbent to absorb the permeated ammonia gas; after the separated ammonia nitrogen wastewater is qualified, it is discharged to the subsequent treatment system or directly discharged. The acrylic acid wastewater (the main component is acetic acid) is absorbed and then circulated into the acrylic acid circulating water tank. When the pH of the absorbent is >5, partial replacement is performed. After the ammonium acetate absorbent is discharged, it can be used as an additive for the electrolyte in the electroplating industry and a complexing agent for the electroplating solution. It can also be used as a nitrogen nutrient for some sewage treatment plants.

[0043] A membrane-based ammonia nitrogen removal system with a hydrophobic ammonia removal membrane 6 is adopted. First, the ammonia nitrogen wastewater is heat-exchanged, filtered, and its pH is adjusted to 11–14 and its temperature to 30–45℃ before being sent to the membrane shell side. Acetic acid-containing wastewater from the acrylic acid unit is sent to the membrane tube side as the absorbent, forming a gas-liquid mass transfer system on both sides of the membrane. NH4+ in the wastewater is converted into NH3 gas at high pH and high temperature, which passes through the hydrophobic membrane pores into the tube side and is absorbed by acetic acid to generate ammonium acetate. After ammonia removal, the wastewater is discharged, and the absorbent is recycled. When the pH is >5, the ammonium acetate is partially replaced and utilized as a resource. This achieves ammonia removal without sulfation, efficient removal of ammonia nitrogen, resource utilization of acrylic acid wastewater, and effluent compliance with standards. The process is safe and low-cost.

[0044] Example 2

[0045] The similarities will not be repeated here. The difference from Example 1 is that two ammonia removal membranes are used, connected in series, and the flux of the ammonia removal membranes is 10m³ / s. 3 With a capacity of / h, the average ammonia nitrogen removal rate reaches 74.04% at a medium treatment scale, balancing treatment efficiency and equipment investment, making it suitable for routine operating conditions.

[0046] Example 3

[0047] The similarities will not be repeated here. The difference from Example 1 is that three deammoniation membranes are installed in series, and the flux of each membrane is 10m³. 3 / h, enhanced mass transfer and multi-stage absorption, the average ammonia nitrogen removal rate increased to 94.24%, meeting the requirements for high concentration of ammonia nitrogen and high standard effluent.

[0048] Comparative Example 1

[0049] Using the same membrane deammoniation system and operating parameters, with dilute sulfuric acid as the absorbent, the two deammoniation membranes are operated in series.

[0050] The influent and product water data during continuous operation of Examples 2, 3, and Comparative Example 1 are shown in Tables 1-3 below (Table 1 shows the operation data for Example 2, Table 2 shows the operation data for Example 3, and Table 3 shows the operation data for Comparative Example 1):

[0051] Table 1

[0052]

[0053] Table 2

[0054]

[0055] Table 3

[0056] date Influent ammonia nitrogen mg / L Ammonia nitrogen in effluent (mg / L) Removal rate April 16, 2025 240.56 52.77 78.06% April 19, 2025 252.98 63.63 74.85% April 22, 2025 240.56 72.94 69.68% April 25, 2025 232.8 57.42 75.34% April 28, 2025 232.8 60.53 74.00% May 1, 2025 190.9 48.11 74.80% May 4, 2025 158.3 51.22 67.64% May 7, 2025 173.82 57.42 66.97% May 10, 2025 167.62 54.32 67.59% May 13, 2025 158.3 57.42 63.73% May 16, 2025 161.41 54.32 66.35% May 22, 2025 170.78 37.84 77.84% May 25, 2025 136.58 41.9 69.32% May 28, 2025 148.99 48.11 67.71% May 31, 2025 135.02 45.01 66.66% June 3, 2025 135.02 45.01 66.66% June 6, 2025 131.92 38.8 70.59% June 9, 2025 113.3 34.22 69.80% June 12, 2025 111.74 29.41 73.68% June 15, 2025 127.36 28.11 77.93% June 18, 2025 121.57 29.61 75.64% June 21, 2025 125.62 32.3 74.29% June 24, 2025 111.74 28.4 74.58% June 27, 2025 116.4 32.98 71.67% June 30, 2025 111.74 26.07 76.67% July 3, 2025 114.85 27.08 76.42% average value 158.56 44.42 71.98%

[0057] As shown in Tables 1 to 3, when acrylic acid wastewater is used as the absorbent, the average removal rate of two membranes connected in series is 74.04%, which is higher than the 71.98% of the traditional sulfuric acid absorbent, and the absorption effect can completely replace dilute sulfuric acid; when three membranes are connected in series, the removal rate can reach 94.24%, and the treatment effect is significantly improved. At the same time, this invention realizes the resource utilization of acrylic acid wastewater, eliminates the use of sulfuric acid, eliminates safety and regulatory risks, reduces operating costs, and has significant technical advantages and economic benefits.

[0058] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A membrane method for removing ammonia nitrogen, characterized in that: The ammonia nitrogen removal system using a membrane-based deammoniation membrane (6) includes the following steps: S1. After heat exchange and filtration, the ammonia nitrogen wastewater is adjusted to pH 11-14 and the temperature is controlled at 30-45℃ before being fed into the shell side of the hydrophobic ammonia removal membrane (6). S2. The acetic acid-containing wastewater generated by the acrylic acid unit is used as the absorbent and sent to the tube side of the deammoniation membrane (6) by the circulating pump (10) to form a gas-liquid mass transfer system on both sides of the membrane with the shell side wastewater of the deammoniation membrane (6). S3. Ammonium ions in wastewater are converted into gaseous ammonia at high pH and temperature, which enters the tube side through hydrophobic membrane pores and is absorbed by acrylic acid wastewater to generate acetic acid. S4. Wastewater after ammonia nitrogen removal meets discharge standards. The absorbent is recycled. When the pH of the absorbent is greater than 5, partial replacement is performed. The resulting ammonium acetate solution is utilized as a resource.

2. The membrane-based ammonia nitrogen removal method according to claim 1, characterized in that: The membrane-based ammonia nitrogen removal system includes a first plate heat exchanger (1) for exchanging heat with ammonia nitrogen wastewater. The outlet of the first plate heat exchanger (1) is connected to an ammonia nitrogen wastewater raw water tank (2). The outlet of the ammonia nitrogen wastewater raw water tank (2) is connected to a security filter (4) via a raw water pump (3). The outlet of the security filter (4) is connected to a second plate heat exchanger (5). The outlet of the second plate heat exchanger (5) is connected to an ammonia removal membrane (6). One end of the ammonia removal membrane (6) is connected to an acrylic acid wastewater circulating water system for recycling the absorbent. The acrylic wastewater circulating tank (7) is connected to the acrylic raw water tank (8) via the acrylic transfer pump (9) at the feed end. The acrylic wastewater circulating tank (7) is connected to the ammonium acetate filter (11) and the ammonium acetate tank (12) via the circulation pump (10). The ammonium acetate filter (11) is connected to the feed end of the deammonium removal membrane (6) to circulate the absorbent to the deammonium removal membrane (6). The deammonium removal membrane (6) is provided with a transmission pipe for returning qualified product water to the first plate heat exchanger (1).

3. The membrane-based ammonia nitrogen removal method according to claim 2, characterized in that: The deammonia removal membrane (6) is a PTFE hydrophobic hollow fiber membrane. The membrane fibers are woven into a cloth and wound into a column and installed in the membrane shell.

4. The membrane-based ammonia nitrogen removal method according to claim 3, characterized in that: Two deammonia removal membranes (6) are provided, connected in series, and the flux of the deammonia removal membrane (6) is 10m³. 3 / h.

5. The membrane-based ammonia nitrogen removal method according to claim 3, characterized in that: Three deammoniation membranes (6) are provided, connected in series, and the flux of the deammoniation membranes (6) is 10m³. 3 / h.

6. The membrane-based ammonia nitrogen removal method according to claim 3, characterized in that: In step S1, the ammonia nitrogen wastewater after heat exchange and filtration is adjusted to pH 11-14 using a 30% sodium hydroxide solution. The sodium hydroxide solution is added at the front end of the security filter (4).

7. The membrane-based ammonia nitrogen removal method according to claim 2, characterized in that: In step S2, the acetic acid-containing wastewater is filtered through an ammonium acetate filter (11) and then circulated into the deammonium removal membrane (6) tube. When the pH of the acrylic acid wastewater absorbent is greater than 5, partial replacement is performed. The discharged ammonium acetate solution is used as an additive for electroplating electrolyte, an electroplating complexing agent, or a nitrogen nutrient for wastewater treatment plants.

8. The membrane-based ammonia nitrogen removal method according to claim 2, characterized in that: The outer side of the deammoniation membrane (6) is the shell side, through which ammonia nitrogen wastewater is introduced; the inner side of the membrane filaments is the tube side, through which acrylic acid wastewater absorption liquid is introduced.

9. The membrane-based ammonia nitrogen removal method according to claim 2, characterized in that: The first plate heat exchanger (1) uses ammonia nitrogen wastewater and qualified product water for countercurrent heat exchange. After heat exchange, the temperature of ammonia nitrogen wastewater is 15-20℃. The second plate heat exchanger (5) uses ammonia nitrogen wastewater and steam for heat exchange. The steam rate is 10-20m / s, and the wastewater temperature is controlled at 30-45℃.

10. A membrane method for removing ammonia nitrogen according to claim 2, characterized in that: The ammonium acetate tank (12) is connected to a discharge pump (13) for discharging ammonium acetate. The wastewater discharged by the discharge pump (13) is either directly discharged or enters a subsequent treatment system.

Images