Conductive separation net assembly, membrane assembly adopting same and water treatment method

Abstract

The invention provides a conductive separation net assembly, a membrane assembly adopting the same and a water treatment method, the separation net assembly comprises a separation net body, and tin antimony oxide is loaded on the surface of the separation net body through a sol-gel method; the separation net body is made of any one of titanium, aluminum, carbon felt and stainless steel. According to the invention, membrane pollution control by an electric field is combined with a water inlet separation net of a key part in a spiral-wound membrane assembly (nanofiltration membrane assembly or reverse osmosis membrane assembly), the membrane does not need to be subjected to conductive modification, tedious steps are omitted, and compared with a traditional water inlet separation net made of a PP material, the separation net assembly slows down membrane pollution in the operation process under the electrochemical action, and the membrane pollution is reduced. The membrane filtration performance is improved, the service life of the membrane is prolonged, and the effluent quality is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of membrane pollution control, and relates to a conductive spacer assembly, a membrane assembly using the same, and a water treatment method. Background Art

[0002] At present, the deterioration of water environment and the shortage of fresh water resources have become prominent problems. Membrane separation technology has become one of the key technologies for water purification due to its advantages such as no need to add chemical reagents, low energy consumption, and easy operation. Several types of membrane components commonly used in industry include plate and frame, spiral roll, circular tube, and hollow fiber. The spiral roll has the advantages of simple membrane support structure, small concentration polarization, and easy adjustment of membrane surface flow state, making it a more common membrane component in practical applications. The structure of the spiral roll membrane component is composed of a "double-layer structure" assembly with a porous support material in the middle and membranes on both sides. The water inlet spacer is an important component of the roll membrane component. It can separate the membrane, form a flow channel, enhance fluid turbulence and mass transfer, and reduce concentration polarization.

[0003] However, membrane fouling is also one of the important factors that cannot be ignored in the promotion and application of membrane water treatment. Membrane fouling can lead to problems such as reduced membrane flux, deterioration of produced water quality, and increased operation and maintenance costs. Previous studies have found that combining electric fields with membrane water treatment technology can alleviate membrane fouling. In addition, there are studies on changing the physical properties of the separator and preparing high-stability separators with certain antibacterial properties to increase membrane flux and alleviate membrane fouling.

[0004] The prior art solution discloses a method of forming a node characteristic plane at the intersection of the longitudinal mesh and the transverse mesh after hot melting, extrusion or fine grinding, which is beneficial to prevent the concentrated water screen from damaging the adjacent membrane, and at the same time adjusts the number of nodes in some areas to reduce the number of nodes in contact with the membrane, further reducing the damage caused by the screen to the adjacent membrane. However, the patent uses cumbersome and complex processes such as hot melting and extrusion, and the flatness of the nodes after treatment is the same, which weakens the phenomenon of eliminating concentration polarization by the water inlet screen, which is not conducive to alleviating membrane pollution.

[0005] The existing technical solution also discloses a new type of anti-pollution roll-type membrane guide screen, which uses flexible silk ribbons to replace traditional hard ribs and leaves redundant length. When the water flows, the horizontal flexible silk ribbons will vibrate, which can improve the mass transfer efficiency, increase the membrane flux, and improve the anti-pollution performance of the membrane; and its longitudinal ribs extend in a wavy shape, with a small contact point area, which reduces the probability of filtering dead corners. However, this patent uses a method of replacing hard ribs with flexible silk strips, and the area of ​​the nodes is small, which easily reduces the support strength of the guide screen itself, causing damage to the membrane assembly during operation and reducing the life of the membrane assembly.

[0006] At present, the modification of roll membranes is mostly focused on modifying the physical properties such as the shape of the mesh and the thickness of the strips to alleviate membrane pollution, without changing its chemical properties and without conductive properties. Methods combined with mitigating membrane pollution include adding chemical agents, but such methods have high drug consumption and are prone to secondary pollution. Therefore, there is an urgent need to design a conductive mesh assembly for in-situ control of membrane pollution and a membrane assembly and water treatment method using the same to overcome the defects of the existing technology and meet the needs of practical applications. Summary of the invention

[0007] In view of the deficiencies in the prior art, the object of the present invention is to provide a conductive screen assembly and a membrane assembly and a water treatment method using the same. In the present invention, the electric field control of membrane pollution is combined with the water inlet screen, which is a key part of the rolled membrane assembly. There is no need to conduct conductive modification on the membrane, and cumbersome steps are omitted. Compared with the traditional PP water inlet screen, the screen assembly reduces membrane pollution during operation under the action of electrochemistry, improves membrane filtration performance, extends the service life of the membrane, and improves effluent quality.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a conductive screen assembly, comprising a screen body, the surface of which is loaded with tin antimony oxide by a sol-gel method; the screen body is made of any one of titanium, aluminum, carbon felt and stainless steel.

[0010] In the present invention, the electric field control of membrane pollution is combined with the water inlet screen, which is a key part of the rolled membrane assembly. There is no need to conduct conductive modification on the membrane, and cumbersome steps are omitted. Compared with the traditional PP water inlet screen, the screen assembly slows down membrane pollution during operation under the action of electrochemistry, improves membrane filtration performance, extends the service life of the membrane, and improves the effluent quality.

[0011] It should be noted that the present invention increases the conductivity of the screen by changing the material properties of the screen body, utilizes electrochemical action, and reduces membrane pollution in situ to increase the water production flux. Currently, the main methods of controlling membrane pollution by electrochemical methods include external electric field, conductive membrane modification, etc. The present invention can utilize electric field and electrochemical action to reduce the distance between the electrode plate and the membrane without adding scale inhibitors, and modify the material of the water inlet screen, an important structure in the rolled membrane assembly, thereby innovatively combining electrochemical methods to control membrane pollution.

[0012] It should be noted that conventional roll-type membrane diversion mesh materials do not have conductive properties. Generally, the invention mainly improves the shape, thickness, and spacing of the material, and does not change the material itself. The traditional method is to directly load the original mesh. Since the original base material is a non-conductive material, the conductivity is poor after the coating load, and it is easy to fall off at a certain temperature, which cannot effectively alleviate the effect of membrane pollution. Therefore, the present invention improves the properties of the mesh body, uses titanium wire as the substrate, and modifies the components without affecting the diversion effect. It can improve the conductivity of the mesh, and it does not fall off under different actual pressure and flow rate conditions. It has good stability and can be effectively used in roll-type membranes. It has good industrial prospects in the future.

[0013] It should be noted that the specific operation of the sol-gel method in the present invention can be: the precursors of the required components are prepared into a mixed solution, and after forming a sol, it is continuously heated to make it a gel, and the prepared gel is coated on a titanium substrate, placed in an oven and heated at a temperature of 140°C for 15 minutes, and then transferred to a muffle furnace at 400°C for calcination. The calcination duration is 3 hours, and it can be taken out after the temperature is cooled. Tin antimony oxide is selected because its chemical properties are less active and the effect is more stable than other metals and their oxides.

[0014] As a preferred technical solution of the present invention, the mesh diameter of the partition body is 0.1-2 mm, for example, it can be 0.1 mm, 0.3 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] The mesh diameter of the separator body in the present invention is 0.1-2 mm because the thickness of the conductive separator is moderate within this range, which plays a role in guiding the separator without damaging the membrane surface. If it is not within this range, the conductive separator will be too thick, which will easily damage the membrane surface and cause a significant decrease in the salt rejection rate.

[0016] As a preferred technical solution of the present invention, the mesh shape of the partition body is square or diamond.

[0017] In a second aspect, the present invention provides a membrane assembly, the membrane assembly comprising a counter electrode, a filter membrane and the spacer assembly described in the first aspect, which are stacked in sequence;

[0018] The filter membrane is a nanofiltration membrane or a reverse osmosis membrane.

[0019] As a preferred technical solution of the present invention, the material of the counter electrode is any one of stainless steel, aluminum, titanium and graphite.

[0020] As a preferred technical solution of the present invention, the nanofiltration membrane is a polyamide composite membrane.

[0021] It should be noted that the nanofiltration membrane in the present invention can be a polyamide composite membrane with a model number of NF270-4040.

[0022] Preferably, the maximum operating temperature of the filter membrane is 40-45°C, for example, it can be 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] Preferably, the operating pressure of the filter membrane is 0.6-6 MPa, for example, it can be 0.6 MPa, 0.8 MPa, 1.0 MPa, 2.0 MPa, 3.0 MPa, 4.0 MPa, 5.0 MPa, 6.0 MPa, etc., but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] In a third aspect, the present invention provides a water treatment method for alleviating membrane fouling, wherein the water treatment method uses the membrane assembly described in the second aspect for treatment, and the water treatment method comprises:

[0025] The raw water is treated by pretreatment, nanofiltration unit or reverse osmosis unit to obtain purified water;

[0026] The membrane assembly is used in the treatment of a nanofiltration unit or a reverse osmosis unit, the screen assembly is used as an anode, the counter electrode is used as a cathode, and the anode and the cathode are energized to alleviate the membrane pollution of the nanofiltration membrane or the reverse osmosis membrane accordingly;

[0027] Alternatively, the screen assembly is used as the cathode and the counter electrode is used as the anode.

[0028] It should be noted that the pretreatment in the present invention may include coagulation sedimentation, electroflocculation, ultrafiltration and sand filtration, etc. After simple pretreatment, the raw water enters the nanofiltration treatment unit or the reverse osmosis unit. After the nanofiltration treatment or the reverse osmosis treatment, the hardness can be effectively removed and the water quality can be improved. During the operation of the nanofiltration membrane or the reverse osmosis membrane, a membrane assembly is placed and operated in a cross-flow manner.

[0029] As a preferred technical solution of the present invention, the raw water is brackish water or sea salt water.

[0030] It should be noted that the brackish water in the present invention generally refers to water with an alkalinity greater than hardness, containing a large amount of neutral salts, and a pH value greater than 7; sea salt water generally refers to high-hardness water with a certain concentration of salt but a TDS content lower than that of seawater, with a TDS of about 3000-10000 and a hardness between 300-1000.

[0031] Preferably, the nanofiltration membrane is compacted before being processed by the nanofiltration unit.

[0032] It should be noted that, in the present invention, the nanofiltration membrane is compacted before the nanofiltration unit is processed, so that the operation effect of the nanofiltration membrane can be more stable.

[0033] Preferably, the pressure of the compaction treatment is 0.6-1.0 MPa, for example, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] Preferably, the compaction treatment time is 30 to 60 minutes, for example, 30 minutes, 40 minutes, 50 minutes, 60 minutes, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] The compaction treatment pressure in the present invention is 0.6-1.0 MPa and the time is 30-60 min, because within this range the membrane water flux remains stable. If it is not within this range, it will lead to unstable water production and fluctuating water flux changes. If the pressure is too low, the water production is less; if the pressure is too high, the energy consumption is high.

[0036] As a preferred technical solution of the present invention, the conductivity of the raw water is 1500-5000μs / cm, for example, it can be 1500μs / cm, 2000μs / cm, 3000μs / cm, 4000μs / cm, 5000μs / cm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] Preferably, the pH of the raw water is 7.5-8.5, for example, it can be 7.5, 7.6, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4, 8.5, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] Preferably, a direct current power supply is used in the power-on process.

[0039] Preferably, the voltage in the power-on process is 1 to 6V, preferably 1 to 5V; for example, it can be 1V, 2V, 3V, 4V, 5V, 6V, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] The voltage in the power-on treatment in the present invention is 1-6V because within this range, an electrochemical reaction occurs at the screen interface, which can effectively control membrane fouling. If it is not within this range, the membrane fouling will not be significantly alleviated or the chemical properties of the membrane itself will be destroyed, resulting in adverse changes in membrane water production or salt interception.

[0041] Preferably, the current in the power-on process is 1-6A, preferably 1-5A; for example, it can be 1A, 2A, 3A, 4A, 5A, 6A, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] The current in the power-on treatment in the present invention is 1 to 6A because within this range, an electrochemical reaction occurs at the screen interface, which can effectively control membrane fouling. If it is not within this range, the membrane fouling will not be significantly alleviated or the chemical properties of the membrane itself will be destroyed, resulting in adverse changes in membrane water production or salt interception.

[0043] It should be noted that the regulation of current and voltage in the power-on process of the present invention can be achieved through computer-side programming operations.

[0044] As a preferred technical solution of the present invention, during the operation of the water treatment method, the pH of the nanofiltration membrane is 2 to 11, for example, it can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0045] Preferably, during the operation of the water treatment method, the operating pressure of the membrane assembly is 0.6-1.0 MPa, for example, it can be 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, etc., but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] Preferably, during the operation of the water treatment method, the operating temperature of the membrane assembly is 25-30°C, for example, it can be 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, etc., but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0047] Preferably, the effective membrane area of ​​the nanofiltration membrane is 20 to 21 cm 2 , for example, it can be 20cm 2 、20.1cm 2 、20.2cm 2 、20.3cm 2 、20.4cm 2 、20.5cm 2 、20.6cm 2 、20.7cm 2、20.8cm 2 、20.9cm 2 、21cm 2 The above range is not limited to the listed values, and other values ​​not listed within the above range are also applicable.

[0048] It should be noted that the effective membrane area of ​​the nanofiltration membrane in the present invention refers to the actual area of ​​the nanofiltration membrane under experimental conditions.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] (1) The present invention combines the electric field control of membrane fouling with the key part of the spiral membrane assembly, the water inlet screen. Compared with the traditional PP material water inlet screen, the screen assembly slows down the membrane fouling during operation under the electrochemical action, improves the membrane filtration performance, prolongs the service life of the membrane, and improves the effluent water quality;

[0051] 2) The membrane assembly in the present invention only needs to add electrodes on both sides of the membrane, and there is no need to modify the membrane to make it conductive, thus omitting tedious steps; and compared with a single membrane-applied electric field, it can reduce the distance between the electrode plates, greatly improve the effect of the electric field, and maximize the utilization efficiency of the electric field in controlling membrane pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 A schematic diagram of a conductive screen assembly provided in accordance with a specific embodiment of the present invention Figure 1 ;

[0053] Figure 2 A schematic diagram of a conductive screen assembly provided in accordance with a specific embodiment of the present invention Figure 2 ;

[0054] Figure 3 A schematic diagram of the power supply of a membrane module provided in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0055] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0056] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0057] Those skilled in the art should understand that the present invention necessarily includes necessary pipelines, conventional valves and general pump equipment for realizing a complete process, but the above content does not belong to the main inventive point of the present invention. Those skilled in the art can add layouts on their own based on the process flow and equipment structure selection, and the present invention does not make special requirements and specific limitations on this.

[0058] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0059] In one embodiment, the present invention provides a conductive screen assembly, such as Figure 1 and Figure 2 As shown, the screen assembly includes a screen body, the surface of which is loaded with tin antimony oxide by a sol-gel method; the screen body is made of any one of titanium, aluminum, carbon felt and stainless steel.

[0060] It should be noted that the present invention increases the conductivity of the screen by changing the material properties of the screen body, utilizes electrochemical action, and reduces membrane pollution in situ to increase the water production flux. Currently, the main methods of controlling membrane pollution by electrochemical methods include external electric field, conductive membrane modification, etc. The present invention can utilize electric field and electrochemical action to reduce the distance between the electrode plate and the membrane without adding scale inhibitors, and modify the material of the water inlet screen, an important structure in the rolled membrane assembly, thereby innovatively combining electrochemical methods to control membrane pollution.

[0061] It should be noted that conventional roll-type membrane diversion mesh materials do not have conductive properties. Generally, the invention mainly improves the shape, thickness, and spacing of the material, and does not change the material itself. The traditional method is to directly load the original mesh. Since the original base material is a non-conductive material, the conductivity is poor after the coating load, and it is easy to fall off at a certain temperature, which cannot effectively alleviate the effect of membrane pollution. Therefore, the present invention improves the properties of the mesh body, uses titanium wire as the substrate, and modifies the components without affecting the diversion effect. It can improve the conductivity of the mesh, and it does not fall off under different actual pressure and flow rate conditions. It has good stability and can be effectively used in roll-type membranes. It has good industrial prospects in the future.

[0062] Furthermore, the mesh diameter of the partition body is 0.1-2 mm, for example, it can be 0.1 mm, 0.3 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0063] Furthermore, the mesh shape of the partition body is square or diamond.

[0064] In another embodiment, the present invention provides a membrane module such as Figure 3 As shown, the membrane assembly includes a counter electrode, a filter membrane and the above-mentioned spacer assembly which are stacked in sequence, wherein the filter membrane is a nanofiltration membrane or a reverse osmosis membrane.

[0065] Furthermore, the material of the counter electrode is any one of stainless steel, aluminum, titanium and graphite.

[0066] Furthermore, the materials of the nanofiltration membrane and the reverse osmosis membrane can generally be independently selected from any one of a polyester reinforced non-woven fabric, a polysulfone porous intermediate support layer, and a polyamide ultra-thin separation layer.

[0067] It should be noted that the nanofiltration membrane in the present invention can be a polyamide composite membrane with a model number of NF270-4040.

[0068] Furthermore, the maximum operating temperature of the filter membrane is 40-45°C, for example, it can be 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0069] Furthermore, the operating pressure of the filter membrane is 0.6-6 MPa, for example, it can be 0.6 MPa, 0.8 MPa, 1.0 MPa, 2.0 MPa, 3.0 MPa, 4.0 MPa, 5.0 MPa, 6.0 MPa, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0070] In another specific embodiment, the present invention provides a water treatment method for alleviating membrane fouling, wherein the water treatment method uses the above-mentioned membrane module for treatment, and the water treatment method comprises:

[0071] The raw water is treated by pretreatment, nanofiltration unit or reverse osmosis unit to obtain purified water;

[0072] In the nanofiltration unit or reverse osmosis unit treatment, a membrane assembly is used, the spacer assembly is used as the anode, the counter electrode is used as the cathode, and the anode and the cathode are energized to alleviate the membrane pollution of the nanofiltration membrane or the reverse osmosis membrane accordingly;

[0073] Alternatively, the screen assembly is used as the cathode and the counter electrode is used as the anode.

[0074] It should be noted that after simple pretreatment, the raw water enters the nanofiltration treatment unit or the reverse osmosis unit. After nanofiltration treatment or reverse osmosis treatment, the hardness can be effectively removed and the water quality can be improved. During the operation of the nanofiltration membrane or the reverse osmosis membrane, the membrane assembly is placed and operated in a cross-flow manner.

[0075] Furthermore, the raw water is brackish water or sea salt water.

[0076] Furthermore, the nanofiltration membrane is compacted before the nanofiltration unit treatment.

[0077] Furthermore, the pressure of the compaction treatment is 0.6-1.0 MPa, for example, it can be 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, etc., but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0078] Furthermore, the compaction treatment time is 30 to 60 minutes, for example, 30 minutes, 40 minutes, 50 minutes, 60 minutes, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0079] Furthermore, the conductivity of raw water is 1500-5000μs / cm, for example, it can be 1500μs / cm, 2000μs / cm, 3000μs / cm, 4000μs / cm, 5000μs / cm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0080] Furthermore, the pH of the raw water is 7.5 to 8.5, for example, it can be 7.5, 7.6, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4, 8.5, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0081] Furthermore, a direct current power source is used in the power-on process.

[0082] Furthermore, the voltage in the power-on process is 1 to 6V, and further 1 to 5V; for example, it can be 1V, 2V, 3V, 4V, 5V, 6V, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0083] Furthermore, the current in the power-on process is 1 to 6A, and further 1 to 5A; for example, it can be 1A, 2A, 3A, 4A, 5A, 6A, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0084] It should be noted that the regulation of current and voltage in the power-on process of the present invention can be achieved through computer-side programming operations.

[0085] Furthermore, during the operation of the water treatment method, the pH of the nanofiltration membrane is 2 to 11, for example, it can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0086] Furthermore, during the operation of the water treatment method, the operating pressure of the membrane assembly is 0.6 to 1.0 MPa, for example, it can be 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0087] Furthermore, during the operation of the water treatment method, the operating temperature of the membrane assembly is 25-30°C, for example, it can be 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0088] Furthermore, the effective membrane area of ​​the nanofiltration membrane is 20-21 cm 2, for example, it can be 20cm 2 、20.1cm 2 、20.2cm 2 、20.3cm 2 、20.4cm 2 、20.5cm 2 、20.6cm 2 、20.7cm 2 、20.8cm 2 、20.9cm 2 、21cm 2 The above range is not limited to the listed values, and other values ​​not listed within the above range are also applicable.

[0089] Example 1

[0090] This embodiment provides a water treatment method for alleviating membrane fouling, wherein:

[0091] The membrane fouling experiment lasted for 8 hours, and the raw water was typical brackish water with high hardness, including Ca 2+ The concentration is 200 mg / L, and humic acid is added to simulate natural organic matter with a concentration of 0.5 mg / L. The operating pressure is 0.8 MPa, the constant current is 2 mA, and the voltage is 3 V.

[0092] The raw water is processed by pretreatment and nanofiltration unit to obtain purified water.

[0093] In the nanofiltration unit treatment, a membrane assembly is used, with a titanium-composite tin-antimony screen assembly as the anode and a counter electrode as the cathode. The anode and the cathode are energized to alleviate membrane contamination of the nanofiltration membrane.

[0094] Before the nanofiltration unit treatment, the nanofiltration membrane was compacted at a pressure of 0.8 MPa for 31 minutes.

[0095] The conductivity of the raw water is 2400 μs / cm, and the pH of the raw water is 8.2.

[0096] Example 2

[0097] This embodiment provides a water treatment method for alleviating membrane fouling, wherein:

[0098] The membrane fouling experiment lasted for 8 hours, and the raw water was typical brackish water with high hardness, including Ca 2+ The concentration is 200 mg / L, and humic acid is added to simulate natural organic matter with a concentration of 0.5 mg / L. The operating pressure is 0.8 MPa, the constant current is 4 mA, and the voltage is 4V.

[0099] The raw water is processed by pretreatment and nanofiltration unit to obtain purified water.

[0100] In the nanofiltration unit treatment, a membrane assembly is used, with a stainless steel composite tin-antimony mesh assembly as the anode and a counter electrode as the cathode. The anode and the cathode are energized to alleviate membrane contamination of the nanofiltration membrane.

[0101] Before the nanofiltration unit treatment, the nanofiltration membrane was compacted at a pressure of 0.8 MPa for 30 minutes.

[0102] The conductivity of the raw water is 2100 μs / cm, and the pH of the raw water is 7.5.

[0103] Example 3

[0104] This embodiment provides a water treatment method for alleviating membrane fouling, wherein:

[0105] The membrane fouling experiment lasted for 8 hours, and the raw water was typical brackish water with high hardness, including Ca 2+ The concentration is 200 mg / L, and humic acid is added to simulate natural organic matter with a concentration of 0.5 mg / L. The operating pressure is 0.8 MPa, the constant current is 1 mA, and the voltage is 1V.

[0106] The raw water is processed by pretreatment and nanofiltration unit to obtain purified water.

[0107] In the nanofiltration unit treatment, a membrane assembly is used, with a screen assembly made of aluminum-composite tin-antimony as the anode and a counter electrode as the cathode. The anode and the cathode are energized to alleviate membrane contamination of the nanofiltration membrane.

[0108] Before the nanofiltration unit treatment, the nanofiltration membrane was compacted at a pressure of 0.81 MPa for 31 minutes.

[0109] The conductivity of the raw water is 2000 μs / cm, and the pH of the raw water is 8.

[0110] Example 4

[0111] This embodiment provides a water treatment method for alleviating membrane fouling, wherein:

[0112] The membrane fouling experiment lasted for 8 hours, and the raw water was typical brackish water with high hardness, including Ca 2+ The concentration is 200 mg / L, and humic acid is added to simulate natural organic matter with a concentration of 0.5 mg / L. The operating pressure is 0.8 MPa, the constant current is 5 mA, and the voltage is 5V.

[0113] The raw water is processed by pretreatment and nanofiltration unit to obtain purified water.

[0114] In the nanofiltration unit treatment, a membrane assembly is used, with a carbon felt composite tin-antimony material separator assembly as the anode and a counter electrode as the cathode. The anode and the cathode are energized to alleviate membrane contamination of the nanofiltration membrane.

[0115] Before the nanofiltration unit treatment, the nanofiltration membrane was compacted at a pressure of 0.85 MPa for 32 minutes.

[0116] The conductivity of the raw water is 3000 μs / cm, and the pH of the raw water is 8.5.

[0117] Comparative Example 1

[0118] This comparative example provides a water treatment method for alleviating membrane pollution, wherein the difference from Example 1 is that the material of the screen assembly is titanium screen, and there is no composite tin antimony oxide, and the other parameters and test conditions are the same as those of Example 1.

[0119] Comparative Example 2

[0120] This comparative example provides a water treatment method for alleviating membrane fouling, wherein the difference from Example 1 is that the screen assembly is a polypropylene screen, and the other parameters and test conditions are the same as those of Example 1.

[0121] Comparative Example 3

[0122] This comparative example provides a water treatment method for alleviating membrane fouling, wherein the difference from Example 1 is that the screen assembly is a stainless steel screen, and the other parameters and test conditions are the same as those of Example 1.

[0123] Comparative Example 4

[0124] This comparative example provides a water treatment method for alleviating membrane fouling, wherein the method differs from Example 1 in that no screen assembly is provided, and other parameters and test conditions are the same as those of Example 1.

[0125] The membrane flux and salt rejection rate of the membranes before and after treatment with different spacer components in the above embodiments and comparative examples were tested, wherein the membrane flux is an important process operation parameter of the membrane separation process, which refers to the amount of fluid passing through a unit membrane area per unit time. The calculation formula of the flux is: flux J = V / (T×A), wherein V is the total volume of effluent during the permeation process, A is the effective area of ​​the membrane, and T is the test time result; the salt rejection rate is calculated according to the formula: R = (1-C1 / C0)*100%, R is the rejection rate, C1 is the permeate concentration, and C0 is the feed liquid concentration. As shown in Table 1 below.

[0126] Table 1 Test results of membrane flux and salt rejection in Examples and Comparative Examples

[0127]

[0128] The membrane flux and salt rejection rate of the membrane before and after being treated with the titanium-composite-tin-antimony screen assembly in the above Example 1 were tested under different current conditions. The results are shown in Table 2 below.

[0129] Table 2 Test results of membrane flux and salt rejection under different current conditions in Example 1

[0130]

[0131]

[0132] In summary, the present invention combines the electric field control of membrane pollution with the water inlet screen, which is a key part of the rolled membrane assembly. There is no need to conduct conductive modification on the membrane, and omits tedious steps. Compared with the traditional PP water inlet screen, the screen assembly reduces membrane pollution during operation under the action of electrochemistry, improves membrane filtration performance, extends the service life of the membrane, and improves effluent quality.

[0133] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A conductive screen assembly, characterized in that: The screen assembly comprises a screen body, and the surface of the screen body is loaded with tin antimony oxide by a sol-gel method; The material of the partition body is any one of titanium, aluminum, carbon felt and stainless steel.

2. The screen assembly according to claim 1, characterized in that: The mesh aperture of the partition body is 0.1-2 mm.

3. The screen assembly according to claim 1 or 2, characterized in that: The mesh shape of the partition body is square or diamond.

4. A membrane module, characterized in that: The membrane assembly comprises a counter electrode, a filter membrane and a screen assembly according to any one of claims 1 to 3 which are stacked in sequence; The filter membrane is a nanofiltration membrane or a reverse osmosis membrane.

5. The membrane module according to claim 4, characterized in that The material of the counter electrode is any one of stainless steel, aluminum, titanium and graphite.

6. The membrane module according to claim 4 or 5, characterized in that: The nanofiltration membrane is a polyamide composite membrane; Preferably, the maximum operating temperature of the filter membrane is 40-45°C; Preferably, the operating pressure of the filter membrane is 0.6-6 MPa.

7. A water treatment method for alleviating membrane fouling, characterized in that: The water treatment method adopts the membrane module according to any one of claims 4 to 6 for treatment, and the water treatment method comprises: The raw water is treated by pretreatment, nanofiltration unit or reverse osmosis unit to obtain purified water; The membrane assembly is used in the treatment of a nanofiltration unit or a reverse osmosis unit, the screen assembly is used as an anode, the counter electrode is used as a cathode, and the anode and the cathode are energized to alleviate the membrane pollution of the nanofiltration membrane or the reverse osmosis membrane accordingly; Alternatively, the screen assembly is used as the cathode and the counter electrode is used as the anode.

8. The water treatment method according to claim 7, characterized in that: The raw water is brackish water or sea salt water; Preferably, before the nanofiltration unit treatment, the nanofiltration membrane is compacted; Preferably, the pressure of the compaction treatment is 0.6-1.0 MPa; Preferably, the compaction treatment time is 30 to 60 minutes.

9. The water treatment method according to claim 7 or 8, characterized in that: The conductivity of the raw water is 1500-5000 μs / cm; Preferably, the pH of the raw water is 7.5 to 8.5; Preferably, a direct current power supply is used in the power-on process; Preferably, the voltage in the power-on process is 1 to 6 V, preferably 1 to 5 V; Preferably, the current in the energization process is 1 to 6A, preferably 1 to 5A.

10. The water treatment method according to any one of claims 7 to 9, characterized in that: During the operation of the water treatment method, the pH of the nanofiltration membrane is 2 to 11; Preferably, during the operation of the water treatment method, the operating pressure of the membrane module is 0.6 to 1.0 MPa; Preferably, during the operation of the water treatment method, the operating temperature of the membrane module is 25 to 30°C; Preferably, the effective membrane area of ​​the nanofiltration membrane is 20 to 21 cm 2 .

Images