An apparatus and method for efficiently intercepting ammonia nitrogen in sewage water by electrochemical coupling reverse osmosis membrane

Abstract

The application relates to a device and method for efficiently intercepting ammonia nitrogen in sewage and waste water by electrochemical coupling reverse osmosis membranes, and relates to the field of water treatment. The device for efficiently intercepting ammonia nitrogen in sewage and waste water by electrochemical coupling reverse osmosis membranes comprises a liquid feed barrel, a circulating pump, a pressurizing valve, a needle valve, a feed separation net, a permeation carrier, a reverse osmosis membrane, an external power supply, a water outlet flowmeter and a tee joint. The feed separation net and the permeation carrier in the actual roll type membrane assembly are used as a cathode and an anode respectively, an electric field penetrating through the reverse osmosis membrane is formed by applying an external voltage, and then the reverse electric field force is used to couple the reverse osmosis membrane to efficiently intercept ammonia nitrogen in sewage and waste water. The application can realize the efficient interception of ammonia nitrogen in sewage and waste water by the reverse osmosis membrane under the conditions of low voltage and high water flux, the ammonia nitrogen removal effect is excellent, the removal rate of the ammonia nitrogen is 98% to 99%, and meanwhile, the high water permeability of the reverse osmosis membrane can be maintained; meanwhile, the device structure is simple, conforms to the actual application, and is easy to enlarge production.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water treatment, in particular to a device and method for efficiently removing ammonia nitrogen in wastewater by electrochemical coupling reverse osmosis membrane. BACKGROUND

[0002] Globally, ammonia nitrogen is one of the main pollutants in wastewater, which not only has a serious impact on the ecological environment of water bodies, but also is a potential threat to human health.

[0003] Currently, the methods for treating ammonia nitrogen wastewater mainly include biological treatment, chemical oxidation and physical adsorption. Biological treatment, such as nitrification and denitrification, uses microorganisms to convert ammonia nitrogen into nitrogen gas, which has the advantages of low cost and environmental friendliness, but the treatment speed is slow and sensitive to environmental conditions such as temperature and pH value. Chemical oxidation method is to add chemical reagents such as chlorine and ozone for oxidation in water body, this method can quickly and effectively remove ammonia nitrogen, but may produce toxic by-products, which poses challenges to subsequent treatment and environmental safety. Physical adsorption method, although simple to operate, involves regular replacement of adsorption materials, so it cannot achieve long-term and efficient ammonia nitrogen removal effect. Compared with the above methods, reverse osmosis membrane technology can provide efficient and rapid treatment effect, stable operation, and does not require chemical additives to avoid secondary pollution.

[0004] However, due to the similarity of the polarity and hydration radius of ammonia nitrogen and water molecules, the rejection ability of reverse osmosis membrane to ammonia nitrogen is still insufficient, and the actual rejection rate is less than 93%, which will lead to the transmembrane diffusion of part of the ammonia nitrogen in wastewater to the product water side. In the prior art, to improve the rejection performance of reverse osmosis membrane to ammonia nitrogen, additional treatment steps such as biochar adsorption or chemical oxidation are usually required, which will increase the treatment cost and complexity. Currently, electrochemical treatment technology has attracted widespread attention due to its ability to effectively remove various pollutants in water. This technology can use electric field to affect the migration of salt ions, and if it is combined with traditional reverse osmosis process, it is expected to improve the rejection ability of the system to ammonia nitrogen.

[0005] The existing electrochemical integrated reverse osmosis system includes conductive membrane system and external electrode assisted system, but in the conductive membrane system, the surface properties of the membrane may be damaged due to the doping of conductive materials. In addition, the introduction of external electrodes as reverse osmosis membrane components will adversely affect the stability of the system. Therefore, it is necessary to explore a more efficient and easily scalable electrochemical coupling reverse osmosis system to improve the rejection rate of ammonia nitrogen. SUMMARY

[0006] In view of the deficiencies of the current electrochemical and reverse osmosis membrane coupling system, the present application provides a device and method for efficiently removing ammonia nitrogen in wastewater by electrochemical coupling reverse osmosis membrane.

[0007] The application utilizes the feed spacer net and the permeate carrier in the actual spiral membrane module as the cathode and the anode respectively, forms the electric field through the reverse osmosis membrane by applying the external voltage, and then utilizes the reverse electric field force to couple the reverse osmosis membrane to efficiently intercept the ammonia nitrogen in the sewage and waste water.

[0008] The application discloses an apparatus for electrochemically coupling a reverse osmosis membrane to efficiently intercept ammonia nitrogen in sewage and waste water.

[0009] The outlet end of the liquid tank 1 is sequentially communicated with the circulating pump 2, the pressurizing valve 3 and the needle valve 4 through pipelines, and the outlet end of the needle valve 4 is communicated with the water inlet of the reverse osmosis membrane 7.

[0010] The reverse osmosis membrane 7 is arranged between the feed spacer net 5 and the permeate carrier 6, the feed spacer net 5 is connected with the negative pole of the external power supply 8 and serves as the cathode, and the permeate carrier 6 is connected with the positive pole of the external power supply 8 and serves as the anode.

[0011] The three-way joint 10 comprises an inlet, an outlet and a branch port, the water outlet of the reverse osmosis membrane 7 is communicated with the inlet of the three-way joint 10 through the water flow meter 9, the branch port of the three-way joint 10 is communicated with the first inlet end of the liquid tank 1, and the concentrated water outlet of the reverse osmosis membrane 7 is communicated with the second inlet end of the liquid tank 1.

[0012] The application discloses an apparatus for electrochemically coupling a reverse osmosis membrane to efficiently intercept ammonia nitrogen in sewage and waste water.

[0013] I. Compacting the reverse osmosis membrane

[0014] Pure water is added into the liquid tank 1, the pure water is delivered to the water inlet of the reverse osmosis membrane 7 through the circulating pump 2, the pure water continuously permeates the reverse osmosis membrane 7 under the action of the external pressure of 6bar-50bar applied by the pressurizing valve 3, meanwhile, the shear flow speed of the surface of the reverse osmosis membrane 7 is adjusted to 10L / h-25L / h by the needle valve 4, and when the pure water permeates the reverse osmosis membrane 7, the reverse osmosis membrane 7 is compacted, thereby obtaining the compacted reverse osmosis membrane.

[0015] The time for the pure water to permeate the reverse osmosis membrane 7 in the step I is 8h-15h.

[0016] II. In the feed liquid barrel 1, the sewage to be treated is added, the pH value of the sewage to be treated is adjusted to 6-7, the sewage to be treated is transported to the water inlet of the reverse osmosis membrane 7 through the circulating pump 2, the sewage on the surface of the reverse osmosis membrane 7 is subjected to an external pressure of 4 bar-50 bar by adjusting the pressure valve 3, at the same time, the shear flow rate on the surface of the reverse osmosis membrane 7 is adjusted to 10 L / h-25 L / h by the needle valve 4, an external gradient voltage of 0-2 V is applied between the feed screen 5 and the permeation carrier 6 by the external power supply 8, and then an electric field penetrating through the reverse osmosis membrane 7 is formed, under the action of the external electric field and the external pressure, water molecules permeate through the reverse osmosis membrane 7, the treated water is discharged from the outlet of the three-way valve 10 through the clean water port and the water flow meter 9 of the reverse osmosis membrane 7, and the treated water is obtained; the ammonia nitrogen is migrated to the feed screen 5 under the action of the reverse electric field force, and is adsorbed on the feed screen 5 to form a double electric layer, thereby reducing the ammonia nitrogen permeation amount of the reverse osmosis membrane 7 and improving the retention rate of the ammonia nitrogen.

[0017] The technical features and beneficial effects of the present application are as follows:

[0018] I. The conventional electrochemical coupling reverse osmosis membrane system includes a conductive membrane system and an external electrode auxiliary system. In the conductive membrane system, although the doping of conductive materials such as carbon nanotubes can directly impart conductivity to the membrane, making it directly serve as an electrode to enhance the charge, the preparation of the conductive membrane faces challenges in material selection and technology, and the doping of the conductive material will damage the performance of the membrane surface, thereby affecting the selectivity and permeability of the membrane. The external electrode auxiliary system needs to add external electrodes in the reverse osmosis system, which leads to the increase of the membrane assembly and the inconvenience of equipment maintenance. In the present application, the cathode and anode are directly taken as the feed screen and the permeation carrier in the roll-type membrane assembly, respectively, an electric field penetrating through the reverse osmosis membrane is formed by applying an external voltage, and then the reverse electric field force is coupled with the reverse osmosis membrane to efficiently retain the ammonia nitrogen in the sewage, the ammonia nitrogen removal effect of the device of the present application is excellent, the removal rate of the ammonia nitrogen is 98%-99%, and at the same time, the high water permeability of the reverse osmosis membrane can be maintained; at the same time, the device has a simple structure, meets the actual application, and is easy to scale up.

[0019] Secondly, when an external voltage is applied to the reverse osmosis membrane 7, an electric field through the reverse osmosis membrane is formed between the feed spacer 5 and the permeate carrier 6. On the one hand, under the action of the concentration difference, ammonia nitrogen can pass through the reverse osmosis membrane 7 into the water production side. On the other hand, under the action of the electric field force, ammonia nitrogen is adsorbed on the cathode of the feed spacer 5 to form a double electric layer, thereby being inhibited from entering the water production side. At the same time, in the present application, the feed spacer 5 on the surface of the membrane acts as a cathode, and the negative charge on the surface of the cathode repels the negative carboxyl functional groups on the surface of the reverse osmosis membrane 7 (polyamide membrane), so that the carboxyl functional groups on the surface of the membrane are buried, thereby reducing the negative charge on the surface of the reverse osmosis membrane 7; since the ammonium ion is positively charged, the reduction of the negative charge on the surface of the membrane can weaken the electrostatic attraction between the ammonium ion and the surface of the membrane, which is also beneficial to increasing the rejection rate of ammonia nitrogen by the reverse osmosis membrane 7; in addition, the application of the electric field through the reverse osmosis membrane 7 on both sides leads to an increase in the dielectric constant inside the reverse osmosis membrane 7, so that a higher degree of dehydration is required when the ammonium ion is dissolved on the surface of the reverse osmosis membrane 7, thereby inhibiting the dissolution of the ammonium ion on the surface of the membrane and further improving the rejection rate of ammonia nitrogen. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Figure 1 is a structural schematic diagram of an apparatus for efficiently rejecting ammonia nitrogen in sewage and wastewater by electrochemical coupling of a reverse osmosis membrane according to the present application;

[0021] Figure 2 Figure 2 is a performance graph of the reverse osmosis membrane for rejecting ammonia nitrogen under different external voltages in Example 2, wherein Ammonia nitrogen rejection is the removal rate of ammonia nitrogen, and Water flux is the water flux. DETAILED DESCRIPTION

[0022] Specific embodiment one: the present embodiment is an apparatus for efficiently rejecting ammonia nitrogen in sewage and wastewater by electrochemical coupling of a reverse osmosis membrane, which comprises a liquid tank 1, a circulating pump 2, a pressure valve 3, a needle valve 4, a feed spacer 5, a permeate carrier 6, a reverse osmosis membrane 7, an external power supply 8, a water flow meter 9 and a tee joint 10.

[0023] The outlet end of the liquid tank 1 is sequentially communicated with the circulating pump 2, the pressure valve 3 and the needle valve 4 through pipelines, and the outlet end of the needle valve 4 is communicated with the water inlet of the reverse osmosis membrane 7.

[0024] The reverse osmosis membrane 7 is arranged between the feed spacer 5 and the permeate carrier 6, the feed spacer 5 acts as a cathode and is connected with the negative electrode of the external power supply 8, and the permeate carrier 6 acts as an anode and is connected with the positive electrode of the external power supply 8.

[0025] The tee joint 10 includes an inlet, an outlet and a branch port; the purified water port of the reverse osmosis membrane 7 is connected with the inlet of the tee joint 10 through the outlet flow meter 9, and the branch port of the tee joint 10 is connected with the first inlet end of the liquid tank 1, and the concentrated water port of the reverse osmosis membrane 7 is connected with the second inlet end of the liquid tank 1.

[0026] Specific implementation two: the difference between this embodiment and specific implementation one is that the material of the feed separation net 5 is a metal electrode, a non-metal electrode or a doped modified electrode; the material of the permeation carrier 6 is a metal electrode, a non-metal electrode or a doped modified electrode. The other steps are the same as specific implementation one.

[0027] Specific implementation three: the difference between this embodiment and one of specific implementation one or two is that the metal electrode is an Ir electrode, a Ru electrode, a Pt electrode or a ruthenium iridium electrode; the non-metal electrode is a carbon electrode or a graphite electrode; the doped modified electrode is an electrode obtained by doping and modifying an Ir electrode, a Ru electrode or a graphite electrode. The other steps are the same as specific implementation one or two.

[0028] Specific implementation four: the difference between this embodiment and one of specific implementation one to three is that the reverse osmosis membrane 7 is a low-pressure reverse osmosis membrane or a high-pressure reverse osmosis membrane. The other steps are the same as specific implementation one to three.

[0029] Specific implementation five: the difference between this embodiment and one of specific implementation one to four is that the low-pressure reverse osmosis membrane 7 is a commercial polyamide reverse osmosis composite membrane BW30XLE, which is composed of a PA layer, a support layer and a non-woven fabric, and the thickness of the PA layer is 100nm-200nm. The other steps are the same as specific implementation one to four.

[0030] Specific implementation six: the difference between this embodiment and one of specific implementation one to five is that the voltage range of the external power supply 8 is 0-2V. The other steps are the same as specific implementation one to five.

[0031] Specific implementation seven: the difference between this embodiment and one of specific implementation one to six is that the sewage to be treated in the liquid tank 1 is municipal sewage, industrial wastewater, landfill leachate or sewage that needs to be efficiently intercepted for ammonia nitrogen. The other steps are the same as specific implementation one to six.

[0032] Specific implementation eight: this embodiment is a method for efficiently intercepting ammonia nitrogen in sewage by electrochemical coupling reverse osmosis membrane, which is completed by using a device for efficiently intercepting ammonia nitrogen in sewage by electrochemical coupling reverse osmosis membrane, and specifically includes the following steps:

[0033] I. Compacting the reverse osmosis membrane:

[0034] In the feed liquid barrel 1, pure water is added, and the pure water is delivered to the water inlet of the reverse osmosis membrane 7 by the circulating pump 2. Under the action of the 6 bar-50 bar external pressure applied by the pressurizing valve 3, the pure water continuously permeates the reverse osmosis membrane 7, and the needle valve 4 adjusts the shear flow rate on the surface of the reverse osmosis membrane 7 to be 10 L / h-25 L / h. When the pure water permeates the reverse osmosis membrane 7, the reverse osmosis membrane 7 is compacted, and the compacted reverse osmosis membrane is obtained;

[0035] The time for the pure water to permeate the reverse osmosis membrane 7 in step one is 8 h-15 h.

[0036] II. In the feed liquid barrel 1, the wastewater to be treated is added, and the pH value of the wastewater to be treated is adjusted to be 6-7. The wastewater to be treated is delivered to the water inlet of the reverse osmosis membrane 7 by the circulating pump 2. The pressurizing valve 3 applies 4 bar-50 bar external pressure to the wastewater on the surface of the reverse osmosis membrane 7, and the needle valve 4 adjusts the shear flow rate on the surface of the reverse osmosis membrane 7 to be 10 L / h-25 L / h. An external gradient voltage of 0-2 V is applied between the feed separation net 5 and the permeation carrier 6 by the external power supply 8, thereby forming an electric field penetrating through the reverse osmosis membrane 7. Under the action of the external electric field and the external pressure, water molecules permeate through the reverse osmosis membrane 7. The treated water is obtained by flowing out from the outlet of the three-way joint 10 through the water outlet of the reverse osmosis membrane 7 and the water flow meter 9. Ammonia nitrogen migrates to the feed separation net 5 under the action of the reverse electric field and is adsorbed on the feed separation net 5 to form a double electric layer, thereby reducing the permeation amount of ammonia nitrogen of the reverse osmosis membrane 7 and improving the retention rate of ammonia nitrogen.

[0037] Specific embodiment nine: the difference between this embodiment and one of the specific embodiments one to eight is that the specific process of applying an external gradient voltage of 0-2 V is as follows: the output voltage of the external power supply 8 is adjusted to change the voltage between the anode and the cathode. The initial voltage value is 0 V, and 0 V is maintained for 1 h-2 h. Then the voltage is increased to 0.5 V, and 0.5 V is maintained for 1 h-2 h. Then the voltage is increased to 1 V, and 1 V is maintained for 1 h-2 h. Then the voltage is increased to 1.5 V, and 1.5 V is maintained for 1 h-2 h. Finally, the voltage is increased to 2 V, and 2 V is maintained for 1 h-2 h. The other steps are the same as those in the specific embodiments one to eight.

[0038] Specific embodiment ten: the difference between this embodiment and one of the specific embodiments one to nine is that the concentration of ammonia nitrogen in the wastewater to be treated is 40 mg / L-800 mg / L; the concentration of ammonia nitrogen in the treated water is 0.5 mg / L-10 mg / L, and the removal rate of ammonia nitrogen is 98%-99%. The other steps are the same as those in the specific embodiments one to nine.

[0039] The beneficial effects of the present application are verified by the following examples:

[0040] Embodiment 1: An apparatus for efficiently removing ammonia nitrogen from waste water by electrochemical coupling reverse osmosis membrane, as shown in the figure, comprising a feed liquid tank 1, a circulating pump 2, a pressurizing valve 3, a needle valve 4, a feed screen 5, a permeate carrier 6, a reverse osmosis membrane 7, an external power supply 8, a water flow meter 9 and a tee joint 10. Figure 1

[0041] The feed liquid tank 1 is used for storing feed liquid.

[0042] The circulating pump 2 is used for transporting feed liquid to the surface of the reverse osmosis membrane and transporting concentrated water passing through the surface of the reverse osmosis membrane and permeate water permeating the reverse osmosis membrane into the feed liquid tank 1 to maintain constant feed liquid concentration.

[0043] The pressurizing valve 3 is used for applying feed pressure.

[0044] The needle valve 4 is used for adjusting shear flow rate on the surface of the reverse osmosis membrane.

[0045] The feed screen 5 serves as a cathode.

[0046] The permeate carrier 6 serves as an anode.

[0047] The external power supply 8 is connected to the cathode and the anode, respectively.

[0048] The water flow meter 9 is used for detecting the flow rate of water produced by the reverse osmosis membrane.

[0049] The outlet end of the feed liquid tank 1 is connected to the circulating pump 2, the pressurizing valve 3 and the needle valve 4 in sequence through pipelines, and the outlet end of the needle valve 4 is connected to the water inlet of the reverse osmosis membrane 7.

[0050] The reverse osmosis membrane 7 is placed between the feed screen 5 and the permeate carrier 6, the feed screen 5 serving as a cathode is connected to the negative electrode of the external power supply 8, and the permeate carrier 6 serving as an anode is connected to the positive electrode of the external power supply 8.

[0051] The tee joint 10 includes an inlet, an outlet and a branch port, the water outlet of the reverse osmosis membrane 7 is connected to the inlet of the tee joint 10 through the water flow meter 9, the branch port of the tee joint 10 is connected to the first inlet end of the feed liquid tank 1, and the concentrated water outlet of the reverse osmosis membrane 7 is connected to the second inlet end of the feed liquid tank 1.

[0052] The feed screen 5 is made of ruthenium-iridium electrode.

[0053] The permeate carrier 6 is made of ruthenium-iridium electrode.

[0054] The low-pressure reverse osmosis membrane 7 is a commercial polyamide reverse osmosis composite membrane BW30XLE, which is composed of a PA layer, a support layer and a non-woven fabric, wherein the thickness of the PA layer is 100 nm.

[0055] The voltage range of the external power supply 8 is 0-2 V.​

[0056] Example 2: A method for efficiently intercepting ammonia nitrogen in sewage water by electrochemical coupling reverse osmosis membrane, which is completed by using the device of Example 1, and specifically includes the following steps:

[0057] I. Compacting reverse osmosis membrane:

[0058] Add pure water into the feed tank 1, and the pure water is delivered to the water inlet of the reverse osmosis membrane 7 by the circulating pump 2. Under the action of 12 bar external pressure applied by the pressurizing valve 3, the pure water continuously penetrates the reverse osmosis membrane 7, and at the same time, the needle valve 4 adjusts the shear flow rate on the surface of the reverse osmosis membrane 7 to 21 L / h. When the pure water penetrates the reverse osmosis membrane 7 for 12 h, the reverse osmosis membrane 7 is compacted, and a compacted reverse osmosis membrane is obtained.

[0059] II. Add the sewage water to be treated into the feed tank 1, and adjust the pH value of the sewage water to be treated to 7. The sewage water to be treated is delivered to the water inlet of the reverse osmosis membrane 7 by the circulating pump 2. Adjust the pressurizing valve 3 to apply 10 bar external pressure to the sewage water on the surface of the reverse osmosis membrane 7, and at the same time, adjust the needle valve 4 to adjust the shear flow rate on the surface of the reverse osmosis membrane 7 to 21.8 L / h. An external gradient voltage of 0-2 V is applied to the feed screen 5 and the penetration carrier 6 by the external power supply 8, thereby forming an electric field through the reverse osmosis membrane 7. Under the action of the external electric field and the external pressure, water molecules penetrate through the reverse osmosis membrane 7, and the treated water is obtained through the outlet of the three-way valve 10. The treated water is collected, and the ammonia nitrogen interception rate of the reverse osmosis membrane is detected, and the results are shown in Table 1. Figure 2 The ammonia nitrogen is affected by the reverse electric field force and migrates to the feed screen 5, where it is adsorbed to form a double electric layer, thereby reducing the ammonia nitrogen penetration of the reverse osmosis membrane 7 and improving the ammonia nitrogen interception rate.

[0060] The specific process of applying an external gradient voltage of 0-2 V is as follows: adjust the output voltage of the external power supply 8 to change the voltage between the anode and the cathode. Take 0 V as the initial voltage value, keep it at 0 V for 1 h, then increase the voltage to 0.5 V, keep it at 0.5 V for 1 h, then increase the voltage to 1 V, keep it at 1 V for 1 h, then increase the voltage to 1.5 V, keep it at 1.5 V for 1 h, and finally increase the voltage to 2 V, keep it at 2 V for 1 h.

[0061] The sewage water to be treated is simulated domestic wastewater, with an initial pH value of 7.0±0.2, an ammonia nitrogen concentration of 60 mg / L, a Cl - concentration of 152 mg / L, and an initial conductivity value of 600 μs / cm.

[0062] The ammonia nitrogen concentration in the treated water is about 1 mg / L, and the removal rate of ammonia nitrogen is 98%-99%.

[0063] Figure 2 The figure of the performance of the reverse osmosis membrane for rejecting ammonia nitrogen under different external voltages in Example 2 is shown in the figure, where Ammonia nitrogen rejection is the removal rate of ammonia nitrogen, and Water flux is the water flux.

[0064] From Figure 2 It can be seen that when the external voltage is applied to 2V, the ammonia nitrogen rejection rate reaches 98%~99%, indicating that the device can efficiently reject ammonia nitrogen in sewage.

Claims

1. A device for efficiently removing ammonia nitrogen from contaminated wastewater by electrochemical coupling reverse osmosis membrane, characterized in that The device comprises a feed liquid barrel (1), a circulating pump (2), a pressurizing valve (3), a needle valve (4), a feed separation net (5), a permeation carrier (6), a reverse osmosis membrane (7), an external power supply (8), a water flow meter (9) and a tee joint (10). The outlet end of the feed liquid barrel (1) is connected with the circulating pump (2), the pressurizing valve (3) and the needle valve (4) in sequence through pipelines, and the outlet end of the needle valve (4) is connected with the water inlet of the reverse osmosis membrane (7). The reverse osmosis membrane (7) is arranged between the feed separation net (5) and the permeation carrier (6), the feed separation net (5) is connected with the negative electrode of the external power supply (8) as a cathode, and the permeation carrier (6) is connected with the positive electrode of the external power supply (8) as an anode. The tee joint (10) comprises an inlet, an outlet and a branch port, the water outlet of the reverse osmosis membrane (7) is connected with the inlet of the tee joint (10) through the water flow meter (9), the branch port of the tee joint (10) is connected with the first inlet end of the feed liquid barrel (1), and the concentrated water outlet of the reverse osmosis membrane (7) is connected with the second inlet end of the feed liquid barrel (1). The feed separation net (5) is made of a metal electrode, a non-metal electrode or a doped modified electrode, and the permeation carrier (6) is made of a metal electrode, a non-metal electrode or a doped modified electrode. The reverse osmosis membrane (7) is a low-pressure reverse osmosis membrane, and the low-pressure reverse osmosis membrane (7) is a commercial polyamide reverse osmosis composite membrane BW30XLE, which comprises a PA layer, a support layer and a non-woven fabric, wherein the thickness of the PA layer is 100nm-200nm.

2. The device for efficiently removing ammonia nitrogen in sewage water by electrochemical coupling reverse osmosis membrane according to claim 1, characterized in that The metal electrode is an Ir electrode, a Ru electrode, a Pt electrode or a ruthenium-iridium electrode, the non-metal electrode is a carbon electrode or a graphite electrode, and the doped modified electrode is an electrode obtained by doping and modifying an Ir electrode, a Ru electrode or a graphite electrode.

3. The device for efficiently removing ammonia nitrogen in sewage water by electrochemical coupling reverse osmosis membrane according to claim 1, characterized in that The voltage range of the external power supply (8) is 0-2V.

4. The device for efficiently removing ammonia nitrogen from contaminated wastewater by electrochemical coupling reverse osmosis membrane according to claim 1, characterized in that The feed liquid barrel (1) is used for treating municipal sewage, industrial wastewater, landfill leachate or wastewater that needs to be efficiently intercepted ammonia nitrogen.

5. A method for efficiently removing ammonia nitrogen in sewage water by electrochemical coupling reverse osmosis membrane, characterized in that The method is completed by using the device according to any one of claims 1-4, and specifically comprises the following steps: I. Compacting the reverse osmosis membrane: Pure water is added into the feed liquid barrel (1), the pure water is delivered to the water inlet of the reverse osmosis membrane (7) through the circulating pump (2), the pure water continuously permeates the reverse osmosis membrane (7) under the action of the external pressure of 6bar-50bar applied by the pressurizing valve (3), the shear flow rate on the surface of the reverse osmosis membrane (7) is adjusted by the needle valve (4) to be 10L / h-25L / h, and when the pure water permeates the reverse osmosis membrane (7), the reverse osmosis membrane (7) is compacted to obtain a compacted reverse osmosis membrane; The time for the pure water to permeate the reverse osmosis membrane (7) in step I is 8h-15h. II. The pH value of the wastewater to be treated is adjusted to 6-7 in the feed tank (1), and the wastewater to be treated is delivered to the water inlet of the reverse osmosis membrane (7) by the circulating pump (2). The pressure valve (3) is adjusted to exert an external pressure of 4-50 bar on the wastewater on the surface of the reverse osmosis membrane (7), while the needle valve (4) is adjusted to adjust the shear flow rate on the surface of the reverse osmosis membrane (7) to 10-25 L / h. An external gradient voltage of 0-2 V is applied between the feed screen (5) and the permeate carrier (6) by the external power supply (8), thereby forming an electric field through the reverse osmosis membrane (7). Under the action of the external electric field and the external pressure, water molecules permeate through the reverse osmosis membrane (7), pass through the clean water outlet and the water flow meter (9) of the reverse osmosis membrane (7), flow out from the outlet of the three-way valve (10), and obtain treated water. Ammonia nitrogen is affected by the reverse electric field and migrates to the feed screen (5), where it is adsorbed to form a double electric layer, thereby reducing the ammonia nitrogen permeation of the reverse osmosis membrane (7) and improving the ammonia nitrogen retention rate. The specific process of applying an external gradient voltage of 0-2 V is as follows: adjust the output voltage of the external power supply (8) to change the voltage between the anode and the cathode, take 0 V as the initial voltage value, keep it at 0 V for 1-2 h, then increase the voltage to 0.5 V, keep it at 0.5 V for 1-2 h, then increase the voltage to 1 V, keep it at 1 V for 1-2 h, then increase the voltage to 1.5 V, keep it at 1.5 V for 1-2 h, and finally increase the voltage to 2 V, keep it at 2 V for 1-2 h.

6. The method for efficiently removing ammonia nitrogen from contaminated wastewater by electrochemical coupling reverse osmosis membrane according to claim 5, characterized in that The concentration of ammonia nitrogen in the wastewater to be treated is 40-800 mg / L, and the concentration of ammonia nitrogen in the treated water is 0.5-10 mg / L, with a removal rate of 98%-99%.

Images