Membrane assembly for efficient solid-liquid separation and use method thereof

Abstract

The invention discloses a solid-liquid efficient separation membrane module and a use method thereof.The membrane module comprises main body membrane frame pressing plates and a main body membrane frame with a water outlet and further comprises a soft cushion layer, the two sides of the main body membrane frame are sequentially fixed with microporous filter membranes and macroporous filter membrane main body membrane frame pressing plates through the main body membrane frame pressing plates, and the main body membrane frame pressing plates are connected with the soft cushion layer; wherein the aperture of the microporous filter membrane is smaller than that of the macroporous filter membrane. The soft cushion layer is arranged between the microporous filter membrane and the main body membrane frame and is used for supporting the macroporous filter membrane and the microporous filter membrane and preventing the filter membranes from being internally sucked, deformed and laterally leaked. The solid-liquid separation membrane has the dual advantages of a macroporous filter membrane and a microporous filter membrane, and the solid-liquid separation effect of high-flux and high-quality produced water can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of solid-liquid separation equipment, and in particular relates to a membrane component for efficient solid-liquid separation and a use method thereof. Background Art

[0002] As a new separation technology, membrane technology has been widely used in gas separation, material separation and solid-liquid separation, among which the demand for membrane products in the field of solid-liquid separation is the largest. The high porosity of the dynamic membrane makes the dynamic membrane have a strong liquid phase permeability, so the water flux is large, and it also has the advantages of simple operation and low economic cost. However, the dynamic membrane has the problem of fluctuating water quality, and the turbidity of the water is often high. The microfiltration membrane has a uniform pore size and high filtration accuracy, so the turbidity of the water is small. In addition, the microfiltration membrane prevents the diffusion of pollutants to the surface and inside of the membrane material while improving the filtration accuracy, reducing the degree of pollution to the membrane material. However, the disadvantages of the microfiltration membrane, such as low water flux and high cost of membrane materials, have greatly limited its application.

[0003] Membrane fouling is an inevitable problem of membrane separation technology. On the one hand, during the filtration process, the floccules or certain solute molecules in the sewage react physically or physicochemically with the membrane surface, or the solute on the membrane surface exceeds its solubility due to concentration gradient, resulting in filter cake layer contamination deposited on the membrane surface; on the other hand, mechanical action may cause adsorption and deposition on the inner and outer surfaces of the membrane, causing the membrane pore size to become smaller or blocked, reducing the membrane flux and separation performance, resulting in pore blockage and contamination of the deposited inner and outer surfaces of the membrane.

[0004] The formation of a cake layer is usually the biggest cause of membrane fouling, but the cake layer can actually act as a secondary membrane (i.e., a dynamic membrane) because it enhances the retention of various pollutants (such as colloids) in many cases, and simple physical cleaning is sufficient to remove the dynamic membrane and restore the filtration efficiency. Therefore, if this characteristic of the cake layer can be utilized, that is, the dynamic membrane first retains large particle pollutants, thereby greatly reducing the pollutants entering the microfiltration membrane, it is expected to provide a new path to alleviate the membrane fouling problem. However, the lack of membrane components with high flux and low effluent turbidity and capable of achieving efficient solid-liquid separation is still a key problem that needs to be solved in the actual engineering applications of the membrane industry. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a membrane assembly for efficient solid-liquid separation and a method of using the same, by adding macroporous filter membranes on the outer sides of both sides of the microporous filter membrane assembly to minimize the problem of microporous filter membrane pollution, thereby combining the dual advantages of macroporous filter membranes and microporous filter membranes in a single system to obtain high-throughput and high-quality effluent, while reducing the frequency of membrane assembly cleaning and the economic cost and energy consumption caused by replacing the membrane assembly.

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

[0007] A membrane module for efficient solid-liquid separation, comprising a main body membrane frame pressing plate and a main body membrane frame with a water outlet. Both sides of the main body membrane frame are sequentially fixed with a microporous filter membrane and a macroporous filter membrane through the main body membrane frame pressing plate, wherein the pore size of the microporous filter membrane is smaller than that of the macroporous filter membrane.

[0008] In one embodiment, the membrane module further comprises a soft cushion layer;

[0009] The soft cushion layer is placed between the microporous filter membrane and the main body membrane frame to support the macroporous filter membrane and the microporous filter membrane, preventing the filter membrane from being deformed by internal suction and leaking.

[0010] In one embodiment, the main body membrane frame pressing plate, the macroporous filter membrane, the microporous filter membrane and the soft cushion layer are all of double-layer structure, and are sequentially combined in the order from far to near the main body membrane frame. Only the middle main body membrane frame is of single-layer structure, and the overall membrane module is symmetric about the main body membrane frame.

[0011] In one embodiment, the main body membrane frame pressing plate and the soft cushion layer are in a "mouth" shape, the main body membrane frame is in a "field" shape, and both the main body membrane frame pressing plate and the main body membrane frame are made of hard materials.

[0012] In one embodiment, the thickness of the soft cushion layer is 2-10 mm, and the material of the soft cushion layer is elastic silica gel.

[0013] In one embodiment, the pore size range of the macroporous filter membrane is 48 microns to 0.85 mm, and the pore size range of the microporous filter membrane is 0.02-1 micron. Further preferably, the pore size of the macroporous filter membrane is 48 microns, and the pore size of the microporous filter membrane is 0.02 micron.

[0014] In one embodiment, the macroporous filter membrane is a nylon mesh or a stainless steel wire mesh, and the microporous filter membrane is a ceramic membrane or a polyvinylidene fluoride membrane.

[0015] The usage method of the membrane module for efficient solid-liquid separation of the present invention comprises the following steps:

[0016] Step 1, install the main body membrane frame pressing plate, the macroporous filter membrane, the microporous filter membrane, the main body membrane frame in the order from far to near the main body membrane frame, or install the main body membrane frame pressing plate, the macroporous filter membrane, the microporous filter membrane, the soft cushion layer, the main body membrane frame in sequence, and fix and press all structures with screws;

[0017] Step 2, place the installed membrane module into the mixed liquid to be separated, and collect the separated liquid from the water outlet through the external pressure of a peristaltic pump;

[0018] Step 3, take out the membrane assembly, remove the screws and replace the macroporous filter membrane and microporous filter membrane of different mesh sizes and materials to form different combinations to process different mixed liquids to be separated.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention has the dual advantages of macroporous filter membrane and microporous filter membrane, and can achieve solid-liquid separation effect with high flux and high-quality water production.

[0021] 2. The present invention can alleviate microfiltration membrane pollution to the greatest extent, reduce the frequency of membrane assembly cleaning, extend the service life of the membrane assembly, and further reduce the energy consumption of backwashing the membrane assembly and the cost of replacing the membrane assembly.

[0022] 3. The combination of macroporous filter membrane and microporous filter membrane can be stably realized in a single system, and the advantages of the two are complementary, without the need for external systems and secondary filtration.

[0023] 4. The present invention fixes and compresses each layer of the structure in sequence by screws, and has the advantages of being detachable and convenient for replacement. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the principle of the membrane assembly of the present invention.

[0025] Figure 2 Schematic diagram of the parallel arrangement of membrane components of the present invention.

[0026] Figure 3 This is a diagram of the application scenario of the membrane component of an embodiment of the present invention.

[0027] Figure 4 It is a comparison chart of the filtration performance of the membrane components of the embodiments of the present invention, specifically referring to 20 mesh nylon mesh combined with microfiltration membrane, 100 mesh nylon mesh combined with microfiltration membrane, and 300 mesh nylon mesh combined with microfiltration membrane.

[0028] Figure 5 It is a comparison chart of membrane resistance of the membrane assembly of the embodiment of the present invention, specifically referring to 20 mesh nylon mesh combined with microfiltration membrane, 100 mesh nylon mesh combined with microfiltration membrane, and 300 mesh nylon mesh combined with microfiltration membrane. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0030] Based on the prior art, the present invention hopes to take advantage of the large water flux of the macroporous filter membrane and the high water quality of the microporous filter membrane, and to combine the dual advantages of the macroporous filter membrane and the microporous filter membrane in a single system by adding macroporous filter membranes on the outside of both sides of the microporous filter membrane, so as to obtain high-flux and high-quality water, and the outer macroporous filter membrane first intercepts large particle impurities and macromolecular pollutants in the water body, etc., to reduce the pollutants entering the internal microporous filter membrane, and to alleviate the pollution problem of the microporous filter membrane to the greatest extent. The present invention preferably adopts a symmetrical structure, and defines the side of each component close to the central symmetry plane as the inner side, and the side away from the central symmetry plane as the outer side.

[0031] like Figure 1 As shown, a membrane assembly for efficient solid-liquid separation of the present invention comprises a main membrane frame pressing plate 1, a macroporous filter membrane 2, a microporous filter membrane 3 and a main membrane frame 5, and may further comprise a soft cushion layer 4, and the main membrane frame 5 has a water outlet. According to the above definition, the side of each component close to the main membrane frame 5 is the inner side, and the side away from the main membrane frame 5 is the outer side.

[0032] Among them, the main membrane frame pressure plate 1 is placed on the outside of the macroporous filter membrane 2, on which all structures are fixed and pressed by screws 7, and a handle 8 can be installed to facilitate the installation and replacement of the membrane assembly. The pore size of the microporous filter membrane 3 is smaller than the pore size of the macroporous filter membrane 2. The macroporous filter membrane 2 is placed between the main membrane frame pressure plate 1 and the microporous filter membrane 3 to intercept large particle pollutants, such as macromolecular colloids, proteins, polysaccharides, etc. The microporous filter membrane 3 is placed between the macroporous filter membrane 2 and the main membrane frame 5 to intercept other pollutants, such as suspended matter, bacteria, algae, etc. The main membrane frame 5 is placed between the two layers of microporous filter membranes 3, and water is discharged through the water outlet 6 at its top.

[0033] The membrane assembly of the present invention adopts a double-layer membrane configuration, which has a large water flux and high water quality, eliminating the need for secondary filtration, and matching membrane materials of different pore sizes and materials according to the water demand, providing a variety of combinations for primary filtration, thereby achieving efficient solid-liquid separation. Since the membrane assembly of the present invention has the dual advantages of macroporous filter membranes and microporous filter membranes, it can obtain high-flux and high-quality water, and greatly alleviate the problem of membrane pollution.

[0034] Furthermore, when a soft cushion layer 4 is included, the microporous filter membrane 3 is placed between the macroporous filter membrane 2 and the soft cushion layer 4, and the soft cushion layer 4 is placed between the microporous filter membrane 3 and the main membrane frame 5, which are used to support the two layers of membrane materials and prevent the filter membrane from internal absorption, deformation, and side leakage. The main membrane frame 5 is placed between the two layers of soft cushion layers 4, and water is discharged through the water outlet 6 at the top thereof.

[0035] like Figure 2 As shown, the main membrane frame pressure plate 1, the macroporous filter membrane 2, the microporous filter membrane 3 and the soft cushion layer 4 are all double-layer structures, which are assembled in sequence from far to near the main membrane frame. Only the middle main membrane frame 5 is a single-layer structure, and the overall membrane assembly is symmetrical about the main membrane frame 5.

[0036] The main membrane frame pressing plate 1, the macroporous filter membrane 2, the microporous filter membrane 3, the soft cushion layer 4 and the main membrane frame 5 are all provided with screw holes of the same specification at the edges of the structures, and each layer of the structure is fixed and pressed in turn by screws 7.

[0037] The main membrane frame pressure plate 1 and the soft cushion layer 4 are in the shape of a "mouth", and the main membrane frame 5 is in the shape of a "field". The main membrane frame pressure plate 1 and the main membrane frame 5 are both made of hard materials, such as organic glass, stainless steel, and ceramics; the soft cushion layer 4 has a thickness of 2 to 10 mm to prevent the filter membrane from being deformed due to internal suction under external pressure and to avoid damage to the membrane. The material of the soft cushion layer 4 can be elastic silicone.

[0038] The two macroporous filter membranes 2 are respectively placed outside the two microporous filter membranes 3. The macroporous filter membranes 2 and the microporous filter membranes 3 are placed in parallel, with the same projected shape and area, forming a double-layer filter membrane structure.

[0039] The macroporous membrane 2 is made of cheap and easily available loose macroporous materials, such as nylon mesh and stainless steel mesh, with pore sizes of 20 mesh, 100 mesh and 300 mesh, which are selected according to the mixed liquid to be separated, and 300 mesh nylon mesh is preferred. The pore size range is roughly between 48 microns and 0.85 mm.

[0040] The microporous filter membrane 3 is made of microporous materials with good interception performance and high water quality, such as ceramic membrane and polyvinylidene fluoride membrane, with a pore size of 0.02 to 1 micron.

[0041] A water outlet 6 is provided on the main membrane frame 5 to discharge water by applying external pressure; a handle 8 is provided to facilitate the use and replacement of the membrane assembly.

[0042] The present invention provides a method for using a membrane assembly for efficient solid-liquid separation, comprising the following steps:

[0043] Step 1: Install the main membrane frame pressure plate 1, macroporous filter membrane 2, microporous filter membrane 3, soft cushion layer 4 (if any), and main membrane frame 5 in order from far to near the main membrane frame, and fix all structures with screws 7.

[0044] Step 2, place the installed membrane assembly into the mixed liquid to be separated by pulling the handle 8 or other means, and collect the separated liquid from the water outlet 6 by applying pressure with a peristaltic pump.

[0045] Step 3, take out the membrane assembly by lifting the handle 8 or other means, remove the screw 7 to replace the macroporous filter membrane 2 and the microporous filter membrane 3 of different mesh sizes and materials, and form different combinations to treat different separation mixed liquids. For example, for a granular solid-liquid mixture such as granular sludge, a 0.85 mm macroporous filter membrane combined with a 0.02 μm microporous filter membrane is used to separate the granular sludge and liquid; for a colloidal liquid such as milk, a 48 μm macroporous filter membrane combined with a 0.02 μm microporous filter membrane is used to remove bacteria and other microorganisms in the milk.

[0046] like Figure 3 As shown, the application of the present invention in an actual anaerobic membrane bioreactor. The integrated double membrane assembly includes a main membrane frame pressure plate 1, a macroporous filter membrane 2, a microporous filter membrane 3, a soft cushion layer 4, a main membrane frame 5, a water outlet 6, a screw 7 and a handle 8, all of which are vertically placed in an anaerobic membrane bioreactor 9. The water outlet 6 of the integrated double membrane assembly is connected to an opening 10 on the reactor wall through a pipeline. The water is filtered under the external pressure of a peristaltic pump 11 and collected in a three-phase separation bottle 12. The paperless recorder 13 records the changes in the transmembrane pressure difference during the filtration process.

[0047] like Figure 4 As shown, according to the principle of the present invention, 20-mesh nylon mesh combined with microfiltration membrane, 100-mesh nylon mesh combined with microfiltration membrane, and 300-mesh nylon mesh combined with microfiltration membrane are designed to filter anaerobic digestion sludge in an actual anaerobic membrane bioreactor. It can be seen that the present invention has better effluent flux and smaller transmembrane pressure difference, i.e., TMP increment, than a single-layer microfiltration membrane, and the 300-mesh nylon mesh combined with microfiltration membrane has the best effect.

[0048] like Figure 5 As shown, according to the principle of the present invention, 20 mesh nylon mesh combined with microfiltration membrane, 100 mesh nylon mesh combined with microfiltration membrane, and 300 mesh nylon mesh combined with microfiltration membrane are designed, and the membrane resistance when filtering anaerobic digestion sludge in an actual anaerobic membrane bioreactor is shown. It can be seen that the present invention has a smaller membrane resistance than a single-layer microfiltration membrane, can alleviate membrane pollution, especially filter cake layer pollution, and 300 mesh nylon mesh combined with microfiltration membrane has the best effect.

[0049] The principle of the present invention is described as follows:

[0050] The present invention forms a novel double-layer membrane assembly for solid-liquid separation by combining a macroporous filter membrane with a microporous filter membrane. Since the macroporous filter membrane located on the outer layer first intercepts large particle impurities and macromolecular pollutants in the water body, reducing the pollutants entering the internal microporous filter membrane, the pollution of the microporous filter membrane is alleviated to the greatest extent. The above process can be completed in a single system. The membrane assembly can have the dual advantages of a macroporous filter membrane and a microporous filter membrane, obtain high-throughput and high-quality effluent, reduce the frequency of membrane assembly cleaning, extend the service life of the membrane assembly, and reduce the energy consumed by backwashing the membrane assembly and the economic cost of replacing the membrane assembly.

Claims

1. A membrane assembly for efficient solid-liquid separation, comprising a main membrane frame pressure plate (1) and a main membrane frame (5) with a water outlet (6), characterized in that: On both sides of the main body membrane frame (5), a microporous filter membrane (3) and a macroporous filter membrane (2) are sequentially fixed by a main body membrane frame pressing plate (1), and the pore size of the microporous filter membrane (3) is smaller than that of the macroporous filter membrane (2).

2. The membrane assembly for efficient solid-liquid separation according to claim 1, characterized in that: The membrane module further includes a soft cushion layer (4); The soft cushion layer (4) is placed between the microporous filter membrane (3) and the main body membrane frame (5) to support the macroporous filter membrane (2) and the microporous filter membrane (3), preventing the filter membrane from being deformed by internal suction and leaking from the side.

3. The membrane assembly for efficient solid-liquid separation according to claim 2, characterized in that: The main body membrane frame pressing plate (1), the macroporous filter membrane (2), the microporous filter membrane (3), and the soft cushion layer (4) are all double-layer structures, and are sequentially combined in the order from far to near the main body membrane frame (5). Only the middle main body membrane frame (5) is a single-layer structure, and the overall membrane module is symmetric about the main body membrane frame (5).

4. The membrane assembly for efficient solid-liquid separation according to claim 2, characterized in that: The main body membrane frame pressing plate (1) and the soft cushion layer (4) are in a "mouth" shape, and the main body membrane frame (5) is in a "field" shape. Both the main body membrane frame pressing plate (1) and the main body membrane frame (5) are made of hard materials.

5. The membrane assembly for efficient solid-liquid separation according to claim 2, characterized in that: The thickness of the soft cushion layer (4) is 2 - 10 mm, and the material of the soft cushion layer (4) is elastic silica gel.

6. The membrane assembly for efficient solid-liquid separation according to claim 1, characterized in that: The pore size range of the macroporous filter membrane (2) is 48 microns - 0.85 mm, and the pore size range of the microporous filter membrane (3) is 0.02 - 1 micron.

7. The membrane assembly for efficient solid-liquid separation according to claim 1, characterized in that: The pore size of the macroporous filter membrane (2) is 48 microns, and the pore size of the microporous filter membrane (3) is 0.02 micron.

8. The membrane assembly for efficient solid-liquid separation according to claim 1, characterized in that: The macroporous filter membrane (2) is a nylon mesh or a stainless steel wire mesh, and the microporous filter membrane (3) is a ceramic membrane or a polyvinylidene fluoride membrane.

9. The method for using the membrane assembly for efficient solid-liquid separation according to any one of claims 1 to 8, characterized in that: It includes the following steps: Step 1, install the main body membrane frame pressing plate (1), the macroporous filter membrane (2), the microporous filter membrane (3), and the main body membrane frame (5) in sequence from far to near the main body membrane frame, or install the main body membrane frame pressing plate (1), the macroporous filter membrane (2), the microporous filter membrane (3), the soft cushion layer (4), and the main body membrane frame (5) in sequence, and fix and press all structures with screws (7); Step 2, put the installed membrane module into the mixed liquid to be separated, and collect the separated liquid from the water outlet (6) by applying pressure with a peristaltic pump; Step 3, take out the membrane module, remove the screws (7) and replace the macroporous filter membrane (2) and the microporous filter membrane (3) with different mesh numbers and materials to form different combinations to process different mixed liquids to be separated.

10. The method of use according to claim 9, characterized in that: The mixed liquid to be separated is a granular solid-liquid mixture, the pore size of the macroporous filter membrane (2) is 0.85 mm, and the pore size of the microporous filter membrane (3) is 0.02 micron; or, the mixed liquid to be separated is a colloidal liquid, the pore size of the macroporous filter membrane (2) is 48 mm, and the pore size of the microporous filter membrane (3) is 0.02 micron.

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