A filter device for water treatment

Abstract

The application provides a filtering device for water treatment, and belongs to the technical field of water treatment. The filtering device comprises a water inlet unit, an external reaction unit (5), a PVDF hollow fiber ultrafiltration membrane filtering unit (4), an ozone preparation and regulation unit, a transmembrane pressure difference detection and recording unit and a water production storage unit. The external reaction unit (5) is arranged between the water inlet unit and the PVDF hollow fiber ultrafiltration membrane filtering unit (4), and the ozone preparation and regulation unit is connected with the PVDF hollow fiber ultrafiltration membrane filtering unit (4). The filtering device of the application realizes the coupling of the membrane shell filtering unit and the in-situ ozone technology on the basis of combining the advantages of the membrane shell filtering unit and the PVDF hollow fiber ultrafiltration membrane, and effectively solves the problem of serious membrane pollution of the membrane shell filtering unit.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and specifically relates to a filtration device for water treatment. Background Technology

[0002] Membrane filtration technology, as a method with high separation accuracy and moderate energy consumption, has been widely used in drinking water treatment processes. Filtration units based on hollow fiber membranes mainly include submerged membrane filtration units and external membrane housing filtration units. Membrane housing filtration units are closed, small-scale filtration units, characterized by their small size, short hydraulic retention time, and simple membrane cleaning. However, membrane housing filtration units face challenges during operation, such as severe membrane fouling, inconvenient flushing operations, frequent flushing, and incompatibility with ozone technology.

[0003] Ozone oxidation technology is a commonly used technique in drinking water treatment, effectively controlling ultrafiltration membrane fouling through its own oxidizing properties. Ozone primarily reduces ultrafiltration membrane pore blockage by oxidizing and degrading organic pollutants in water (humic, fulvic, and proteinaceous pollutants, etc.) into smaller organic molecules. Furthermore, ozone can oxidize pollutants on the ultrafiltration membrane surface and within the pores, alleviating membrane fouling and increasing membrane flux. There are two main methods for implementing ozone oxidation technology: pre-ozone oxidation and in-situ ozone oxidation within the ultrafiltration membrane unit. Under certain conditions, pre-ozone oxidation can effectively control membrane fouling, but the contact time is difficult to control, and it does not utilize the shear force of the bubbles generated by aeration. In contrast, in-situ ozone oxidation effectively solves these two problems, featuring a longer oxidation contact time and effective utilization of ozone bubble shear force, exhibiting significant advantages in membrane fouling control. Summary of the Invention

[0004] This invention is based on the inventors' discovery and understanding of the following facts and problems: combining a membrane housing filter unit with in-situ ozone oxidation can not only leverage the advantages of both but also further improve the system's pollutant degradation efficiency. However, due to the closed structure of the membrane housing filter unit, ozone gas cannot be introduced into the membrane housing filter unit in-situ, preventing the two from being effectively combined.

[0005] The present invention aims to create a filtration device for water treatment, which enables in-situ introduction of ozone into the membrane housing filter unit. While maintaining the inherent advantages of the membrane housing filter unit, it effectively solves the problems existing in the membrane housing filter unit, efficiently controls membrane fouling of the hollow fiber membrane in the membrane housing filter unit, and improves the pollutant degradation efficiency of the system.

[0006] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention proposes a filtration device for water treatment.

[0007] This invention proposes a filtration device for water treatment, comprising an inlet unit, an external reaction unit 5, a PVDF hollow fiber ultrafiltration membrane filtration unit 4, an ozone preparation and control unit, a transmembrane pressure difference detection and recording unit, and a product water storage unit. The external reaction unit 5 is disposed between the inlet unit and the PVDF hollow fiber ultrafiltration membrane filtration unit 4, and the ozone preparation and control unit is connected to the PVDF hollow fiber ultrafiltration membrane filtration unit 4.

[0008] The advantages and technical effects of the filtration device of the present invention are as follows:

[0009] (1) The filtration device of the present invention has an external reaction unit and the external reaction unit is connected to the PVDF hollow fiber ultrafiltration membrane filtration unit. A part of the ozone oxidation reaction can occur in the external reaction unit, and the ozone contact time is extended. This solves the defects caused by the closed structure of the membrane shell. While retaining the advantages of small unit volume, short hydraulic residence time and simple and easy membrane cleaning of the membrane shell, the membrane shell can be coupled with in-situ ozone oxidation technology to solve the serious membrane fouling problem of the membrane shell.

[0010] (2) The filtration unit based on PVDF hollow fiber ultrafiltration membrane has good oxidation resistance and organic matter retention performance. The coupling of PVDF hollow fiber ultrafiltration membrane with in-situ ozone technology can produce a synergistic effect, retain the inherent organic matter retention performance of PVDF hollow fiber ultrafiltration membrane, and improve the antifouling performance of PVDF hollow fiber ultrafiltration membrane.

[0011] (3) Since the filtration device of the present invention performs hydraulic circulation between the PVDF hollow fiber ultrafiltration membrane filtration unit and the external reaction unit, after the ozone preparation and control unit is started, the generated ozone can be transported to the PVDF hollow fiber ultrafiltration membrane filtration unit through the gas pipeline. The ozone fully reacts with the organic matter in the influent through its own oxidizing properties, and converts the organic matter in the influent into small molecules, thereby reducing the fouling of the PVDF hollow fiber ultrafiltration membrane pores in the PVDF hollow fiber ultrafiltration membrane filtration unit and increasing the effluent flux of the PVDF hollow fiber ultrafiltration membrane filtration unit.

[0012] (4) In-situ ozone can interact with organic pollutants trapped on the surface of PVDF hollow fiber ultrafiltration membrane through its own oxidizing properties and ozone bubble shearing effect, thereby controlling the pollution of the PVDF hollow fiber ultrafiltration membrane cake layer and increasing the effluent flux of the PVDF hollow fiber ultrafiltration membrane filtration unit.

[0013] (5) In summary, the filtration device of the present invention belongs to the circulating in-situ ozone-PVDF hollow fiber ultrafiltration membrane shell filtration device. It can realize the coupling of membrane shell filtration unit and in-situ ozone technology on the basis of combining the advantages of membrane shell filtration unit and weakly hydrophilic PVDF hollow fiber ultrafiltration membrane, effectively solving the problem of serious membrane fouling of membrane shell filtration unit.

[0014] Optionally, the water inlet unit is a water inlet tank 8, and the top of the water inlet tank 8 is provided with a first water inlet 8-1 and a second water outlet 8-2.

[0015] Optionally, the external reaction unit 5 includes an ozone exhaust port 5-1, a second circulation interface 5-2, a sealing cover 5-3, an overflow port 5-4, a second water inlet 5-5, and a first circulation interface 5-6. The ozone exhaust port 5-1 and the second circulation interface 5-2 are located on the top of the sealing cover 5-3. The second water inlet 5-5 is connected to the first water outlet 8-2 through a water supply pipeline. A second peristaltic pump (7) and a third valve (15) are installed on the water supply pipeline between the second water inlet 5-5 and the first water outlet 8-2. The overflow port (5-4) is connected to the first water outlet 8-2 through another water supply pipeline.

[0016] Optionally, the overflow port 5-4 is located on the upper side of the external reaction unit 5, the second inlet 5-5 is located on the middle side of the external reaction unit 5, and the first circulation port 5-6 is located on the lower side of the external reaction unit 5.

[0017] Optionally, the PVDF hollow fiber ultrafiltration membrane filtration unit 4 includes a second outlet 4-1, a sealing partition 4-2, a fourth circulation interface 4-3, a weakly hydrophilic PVDF hollow fiber ultrafiltration membrane 4-4, a third circulation interface 4-5, an aeration hole 4-6, an air flushing inlet 4-7, an ozone aeration hole 4-8, a concentrate outlet 4-9, and a perforated sealing partition 4-10; the third circulation interface 4-5 is connected to the first circulation interface 5-6 through a water supply pipeline, and a first peristaltic pump 6 and a fourth valve 16 are installed on the water supply pipeline between the third circulation interface 4-5 and the first circulation interface 5-6; the fourth circulation interface 4-3 is connected to the second circulation interface 5-2 through another water supply pipeline.

[0018] Optionally, the fourth circulation port 4-3 is located on the upper side of the PVDF hollow fiber ultrafiltration membrane filter unit 4, the third circulation port 4-5 is located on the lower side of the PVDF hollow fiber ultrafiltration membrane filter unit 4, the air flushing inlet 4-7, the ozone aeration port 4-8 and the concentrate outlet 4-9 are all located at the bottom of the PVDF hollow fiber ultrafiltration membrane filter unit 4, and the second outlet 4-1 is located at the top of the PVDF hollow fiber ultrafiltration membrane filter unit 4.

[0019] Optionally, the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane 4-4 has a contact angle of 80° to 90°, an average pore size of 0.02 μm, and a porosity of 70% to 80%.

[0020] Optionally, the ozone preparation and control unit includes an air pump 1, a gas rotor flow meter 2, and an ozone generator 3 connected in sequence via a gas pipeline. The outlet of the ozone generator 3 is connected to the ozone aeration holes 4-8 via a gas pipeline. A fifth valve 17 is provided on the gas pipeline between the outlet of the ozone generator 3 and the ozone aeration holes 4-8.

[0021] Optionally, the transmembrane pressure differential detection and recording unit includes a pressure sensor 9 and a paperless recorder 10 electrically connected to the pressure sensor 9. One end of the pressure sensor 9 is connected to the second outlet 4-1 through a water supply pipeline, and the other end of the pressure sensor 9 is connected to the third peristaltic pump 11 through a water supply pipeline.

[0022] Optionally, the water production storage unit is a discharge tank 12. The top of the discharge tank 12 is provided with a third water inlet 12-1 and a third water outlet 12-2. The third water inlet 12-1 is connected to the third peristaltic pump 11 through a water supply pipeline. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the circulating in-situ ozone-PVDF hollow fiber ultrafiltration membrane shell filtration device in Example 1;

[0024] Figure 2 This is a schematic diagram of the PVDF hollow fiber ultrafiltration membrane filtration unit of the filtration device in Example 1;

[0025] Figure 3 This is a schematic diagram of the external reaction unit of the filtration device in Example 1;

[0026] Figure 4 This is a schematic diagram of the water inlet unit of the filtration device in Example 1;

[0027] Figure 5 This is a schematic diagram of the water production storage unit of the filtration device in Example 1;

[0028] Figure 6 This is a schematic diagram of the PVDF hollow fiber ultrafiltration membrane filtration device in Comparative Example 1.

[0029] Figure 7 The fouling status of the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane after the circulating in-situ ozone-PVDF hollow fiber ultrafiltration membrane shell filtration device of Example 1 and the PVDF hollow fiber ultrafiltration membrane filtration device of Comparative Example 1 treated the source water.

[0030] Figure 8The changes in effluent water quality of the circulating in-situ ozone-PVDF hollow fiber ultrafiltration membrane shell filtration device of Example 1 and the PVDF hollow fiber ultrafiltration membrane filtration device of Comparative Example 1 are shown.

[0031] Figure 9 The changes in foaming pressure and multi-bubble point pressure after the circulating in-situ ozone-PVDF hollow fiber ultrafiltration membrane shell filtration device of Example 1 and the PVDF hollow fiber ultrafiltration membrane filtration device of Comparative Example 1 treated the source water.

[0032] Figure 10 The changes in tensile strength after the circulating in-situ ozone-PVDF hollow fiber ultrafiltration membrane shell filtration device of Example 1 and the PVDF hollow fiber ultrafiltration membrane filtration device of Comparative Example 1 treated the source water.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Air pump; 2. Gas rotor flow meter; 3. Ozone generator; 4. PVDF hollow fiber ultrafiltration membrane filter unit; 4-1. Second outlet; 4-2. Sealing partition; 4-3. Fourth circulation interface; 4-4. Weakly hydrophilic PVDF hollow fiber ultrafiltration membrane; 4-5. Third circulation interface; 4-6. Aeration holes; 4-7. Air flushing inlet; 4-8. Ozone aeration hole; 4-9. Concentrate drain; 4-10. Perforated sealing partition; 5. External reaction unit; 5-1. Ozone exhaust port; 5-2. Second circulation interface 5-3. Sealing cap; 5-4. Overflow port; 5-5. Second water inlet; 5-6. First circulation interface; 6. First peristaltic pump; 7. Second peristaltic pump; 8. Water inlet tank; 8-1. First water inlet; 8-2. First water outlet; 9. Pressure sensor; 10. Paperless recorder; 11. Third peristaltic pump; 12. Discharge bucket; 12-1. Third water inlet; 12-2. Third water outlet; 13. First valve; 14. Second valve; 15. Third valve; 16. Fourth valve; 17. Fifth valve; 18. Sixth valve. Detailed Implementation

[0035] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0036] The problem this invention aims to solve is how to integrate the technical advantages of in-situ ozone technology, hollow fiber ultrafiltration membranes, and membrane housing filter units to achieve coupling between membrane housing filter units and in-situ ozone technology. While maintaining the inherent advantages of membrane housing filter units, this invention effectively solves the existing problems of membrane housing filter units and efficiently controls membrane fouling of hollow fiber ultrafiltration membranes within the membrane housing filter unit.

[0037] In-situ ozone oxidation places strict requirements on the material and ozone resistance of ultrafiltration membranes. Ultrafiltration membranes are mainly classified into organic and inorganic membranes. Organic membranes are widely used in drinking water treatment processes due to their low cost and simple preparation. Organic ultrafiltration membranes mainly include PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), and PES (polyethersulfone) membranes. Among them, PVDF ultrafiltration membranes have the advantages of strong chemical resistance and shock resistance. Unmodified PVDF ultrafiltration membranes are weakly hydrophilic, exhibiting a greater affinity for organic matter than for water molecules, effectively retaining organic pollutants in water. However, they face problems such as severe membrane fouling and a sharp drop in membrane flux during filtration. On the other hand, the weakly hydrophilic PVDF ultrafiltration membrane has good ozone resistance, therefore it was chosen as the preferred membrane material for the filtration device of this invention.

[0038] In view of the shortcomings of the existing technology and the characteristics of weakly hydrophilic membranes, this invention proposes a membrane housing filtration device based on in-situ ozone-weakly hydrophilic PVDF hollow fiber ultrafiltration membrane filtration. This device can realize the coupling of membrane housing filtration unit and in-situ ozone technology, effectively solve the problems of severe membrane fouling and frequent backwashing in membrane housing filtration unit, and at the same time improve the pollutant removal rate of the system.

[0039] Specifically, the present invention proposes a filtration device for water treatment, including a water inlet unit, an external reaction unit 5, a PVDF hollow fiber ultrafiltration membrane filtration unit 4, an ozone preparation and control unit, a transmembrane pressure difference detection and recording unit, and a product water storage unit. The external reaction unit 5 is disposed between the water inlet unit and the PVDF hollow fiber ultrafiltration membrane filtration unit 4, and the ozone preparation and control unit is connected to the PVDF hollow fiber ultrafiltration membrane filtration unit 4.

[0040] The design concept of this invention is as follows: Membrane housing filtration units have advantages such as small size, short hydraulic residence time, and simple membrane cleaning, but they suffer from severe membrane fouling and incompatibility with ozone oxidation technology. While weakly hydrophilic PVDF hollow fiber ultrafiltration membranes exhibit good organic matter retention and strong oxidation resistance, they also suffer from severe membrane fouling during filtration. However, in-situ ozone oxidation technology can effectively control ultrafiltration membrane fouling and improve ultrafiltration membrane flux. To address these issues, this invention combines in-situ ozone oxidation technology with a membrane housing filtration unit assembled based on a weakly hydrophilic PVDF hollow fiber ultrafiltration membrane, effectively solving the problem of severe membrane fouling. To overcome the bottleneck of closed-structure membrane housing filters that cannot couple in-situ ozone oxidation technology, this invention proposes to construct an external reaction unit connected to a membrane housing filter unit assembled based on a weakly hydrophilic PVDF hollow fiber ultrafiltration membrane. The external reaction unit and the membrane housing filter unit circulate water via a first peristaltic pump, while ozone is simultaneously introduced in-situ into the membrane housing filter unit, forming a circulating in-situ ozone-weakly hydrophilic PVDF hollow fiber ultrafiltration membrane housing filtration device. This novel filtration device, while retaining the inherent advantages of membrane housing filters, effectively solves the defects of severe membrane fouling and the inability to couple ozone oxidation technology in membrane housing filters.

[0041] Without the external reaction unit 5, ozone cannot be discharged from the membrane shell of the PVDF hollow fiber ultrafiltration membrane filter unit 4 because the gas cannot permeate the ultrafiltration membrane, causing the internal pressure of the membrane shell to increase and the membrane shell to rupture. Therefore, in-situ coupling of ozone technology cannot be achieved in this invention without the external reaction unit 5.

[0042] The present invention will now be described in detail with reference to embodiments and accompanying drawings. In the description of the embodiments of the present invention, it should be understood that the terms "top," "bottom," "side," "left," "right," "upper," and "lower," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are merely for the purpose of simplifying the description of the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, and therefore should not be construed as a limitation of the present invention. The following embodiments are only used to illustrate the present invention, but are not intended to limit the scope of application of the present invention.

[0043] Example 1

[0044] See Figure 1 The circulating in-situ ozone-PVDF hollow fiber ultrafiltration membrane shell filtration device of this embodiment includes a water inlet unit, an external reaction unit, a PVDF hollow fiber ultrafiltration membrane filtration unit, an ozone preparation and control unit, a transmembrane pressure difference detection and recording unit, and a product water storage unit.

[0045] See Figure 4The water inlet unit is a water inlet tank 8, and the top of the water inlet tank 8 is provided with a first water inlet 8-1 and a second water outlet 8-2.

[0046] See Figure 1 and Figure 3 The external reaction unit 5 has a second water inlet 5-5 on the middle side, an overflow port 5-4 on the upper side, a first circulation interface 5-6 on the lower side, a sealing cover 5-3 on the top, and a second circulation interface 5-2 and an ozone exhaust port 5-1 on the sealing cover 5-3.

[0047] See Figure 1 and Figure 2 The PVDF hollow fiber ultrafiltration membrane filter unit 4 is provided with an ozone aeration port 4-8, an air flushing inlet port 4-7, and a concentrate outlet port 4-9 at the bottom. A first valve 13 is provided on the air flushing inlet port 4-7, and a sixth valve 18 is provided on the concentrate outlet port 4-9. A second outlet port 4-1 is provided at the top of the PVDF hollow fiber ultrafiltration membrane filter unit 4. A fourth circulation interface 4-3 is provided on the upper side of the PVDF hollow fiber ultrafiltration membrane filter unit 4, and a third circulation interface 4-5 is provided on the lower side of the PVDF hollow fiber ultrafiltration membrane filter unit 4. The PVDF hollow fiber ultrafiltration membrane filter unit 4 also includes a sealing partition 4-2, a weakly hydrophilic PVDF hollow fiber ultrafiltration membrane 4-4, aeration holes 4-6, and a perforated sealing partition 4-10. The sealing partition 4-2 is located at the top of the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane 4-4, and the perforated sealing partition 4-10 is located at the bottom of the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane 4-4. The perforated sealing partition 4-10 has aeration holes 4-6. The weakly hydrophilic PVDF hollow fiber ultrafiltration membrane 4-4 is bonded between the sealing partition 4-2 and the perforated sealing partition 4-10 with epoxy resin. The sealing partition 4-2 and the perforated sealing partition 4-10 are connected to the inner side of the outer shell of the PVDF hollow fiber ultrafiltration membrane filter unit (4) with epoxy resin.

[0048] Among them, the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane 4-4 has a contact angle of 80° to 90°, an average pore size of 0.02 μm, and a porosity of 70% to 80%.

[0049] See Figure 1The ozone generation and control unit includes an air pump 1, a gas rotor flow meter 2, and an ozone generator 3. The bottom of the air pump 1 and the gas rotor flow meter 2 are connected via a gas pipeline, and the upper part of the gas rotor flow meter 2 is connected to the air inlet of the ozone generator 3 via a gas pipeline. The air pump 1 is used to provide the air required for the ozone generator 3 to generate ozone. The gas rotor flow meter 2 is used to control the flow rate of air delivered by the air pump 1 to the ozone generator 3. The ozone generator 3 is used to generate ozone from the air delivered by the air pump 1 and deliver the generated ozone to the PVDF hollow fiber ultrafiltration membrane filter unit 4.

[0050] See Figure 1 The transmembrane pressure difference detection and recording unit includes a pressure sensor 9 and a paperless recorder 10, with the top of the pressure sensor 9 electrically connected to the paperless recorder 10.

[0051] See Figure 5 The water production storage unit is a discharge tank 12, and the top of the discharge tank 12 is provided with a third water inlet 12-1 and a third water outlet 12-2.

[0052] The connection method between the various units in the filtration device of this embodiment is as follows:

[0053] See Figure 1 The first outlet 8-2 of the water inlet tank 8 is connected to the second inlet 5-5 of the external reaction unit 5 through a water supply pipeline. A second peristaltic pump 7 and a third valve 15 are installed on the water supply pipeline between the first outlet 8-2 and the second inlet 5-5. The water stored in the water inlet tank 8 is transported to the external reaction unit 5 through the second peristaltic pump 7. The overflow port 5-4 of the external reaction unit 5 is connected to the first outlet 8-2 of the water inlet tank 8 through another water supply pipeline. The overflowed water returns to the water inlet tank 8.

[0054] See Figure 1 The first circulation port 5-6 of the external reaction unit 5 is connected to the third circulation port 4-5 of the PVDF hollow fiber ultrafiltration membrane filter unit 4 via a water supply pipeline. A first peristaltic pump 6 and a fourth valve 16 are installed on the water supply pipeline between the first circulation port 5-6 and the third circulation port 4-5. The first peristaltic pump 6 can be used to transport water from the external reaction unit 5 from the first circulation port 5-6 to the third circulation port 4-5. The second circulation port 5-2 of the external reaction unit 5 is connected to the fourth circulation port 4-3 of the PVDF hollow fiber ultrafiltration membrane filter unit 4 via another water supply pipeline. A second valve 14 is installed on the water supply pipeline between the second circulation port 5-2 and the fourth circulation port 4-3. The ozone exhaust port 5-1 of the external reaction unit 5 is used to discharge undissolved ozone exhaust gas.

[0055] See Figure 1The outlet of the ozone generator 3 is connected to the ozone aeration holes 4-8 of the PVDF hollow fiber ultrafiltration membrane filter unit 4 through a gas pipeline. A fifth valve 17 is installed on the gas pipeline between the outlet of the ozone generator 3 and the ozone aeration holes 4-8 of the PVDF hollow fiber ultrafiltration membrane filter unit 4.

[0056] See Figure 1 The bottom right end of pressure sensor 9 is connected to the second outlet 4-1 at the top of PVDF hollow fiber ultrafiltration membrane filter unit 4 via a water supply pipeline. Simultaneously, the bottom left end of pressure sensor 9 is connected to the third inlet 12-1 of discharge tank 12 via a water supply pipeline. A third peristaltic pump 11 is installed on the water supply pipeline between the bottom left end of pressure sensor 9 and the third inlet 12-1 of discharge tank 12. Pressure sensor 9 is connected to the water supply pipeline between the second outlet 4-1 of PVDF hollow fiber ultrafiltration membrane filter unit 4 and the third peristaltic pump 11 to monitor changes in transmembrane pressure difference. Pressure sensor 9 is connected to paperless recorder 10 via a circuit to record transmembrane pressure difference. The second outlet 4-1 is connected to the third peristaltic pump 11 via a water supply pipeline. The negative pressure generated by the rotation of the third peristaltic pump 11 allows water inside PVDF hollow fiber ultrafiltration membrane filter unit 4 to pass through the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane 4-4 and be transported to discharge tank 12.

[0057] It should be noted that, Figure 1 In the diagram, solid lines without arrows or dots represent water pipeline connection methods and operating procedures, solid lines with arrows represent gas pipeline connection methods and operating procedures, and solid lines with dots represent electrical circuit connection methods and operating procedures.

[0058] The working process of the filtration device in this embodiment is as follows:

[0059] This embodiment of the circulating in-situ ozone-weakly hydrophilic PVDF hollow fiber ultrafiltration membrane housing filtration device includes an ozone preparation and control unit, a PVDF hollow fiber ultrafiltration membrane filtration unit, an external reaction unit, an inlet tank, a transmembrane pressure difference detection and recording unit, and a product water storage unit. The ozone preparation and control unit and the PVDF hollow fiber ultrafiltration membrane filtration unit (i.e., the membrane housing filtration unit) are connected. The ozone preparation and control unit generates ozone gas and stably delivers the ozone gas into the membrane housing filtration unit. The PVDF hollow fiber ultrafiltration membrane filtration unit is connected to the external reaction unit, and a first peristaltic pump is used to circulate the water between these two units. The PVDF hollow fiber ultrafiltration membrane filtration unit is composed of a weakly hydrophilic PVDF hollow fiber ultrafiltration membrane. The external reaction unit is connected to the inlet tank, and a second peristaltic pump delivers the inlet water to the external reaction unit. The transmembrane pressure difference detection and recording unit is connected to the outlet of the PVDF hollow fiber ultrafiltration membrane filtration unit to detect the change in transmembrane pressure difference of the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane in the PVDF hollow fiber membrane filtration unit in real time during operation. At the same time, the transmembrane pressure difference detection and recording unit is connected to a third peristaltic pump to perform filtration through negative pressure. The product water storage unit is connected to the third peristaltic pump to collect the product water after the membrane.

[0060] Comparative Example 1

[0061] See Figure 6 The PVDF hollow fiber ultrafiltration membrane filtration device of this comparative example includes a water inlet unit, a PVDF hollow fiber ultrafiltration membrane filtration unit, a transmembrane pressure difference detection and recording unit, and a product water storage unit. The structures of the water inlet unit, the PVDF hollow fiber ultrafiltration membrane filtration unit, the transmembrane pressure difference detection and recording unit, and the product water storage unit are all the same as those in Example 1.

[0062] See Figure 6 The first outlet 8-2 of the water inlet tank 8 is connected to the third circulation interface 4-5 of the PVDF hollow fiber ultrafiltration membrane filter unit through a water supply pipeline. A fourth valve 16 is installed on the water supply pipeline between the first outlet 8-2 and the third circulation interface 4-5.

[0063] See Figure 6 The bottom right side of the pressure sensor 9 is connected to the second outlet 4-1 at the top of the PVDF hollow fiber ultrafiltration membrane filter unit 4 via a water supply pipeline. At the same time, the bottom left side of the pressure sensor 9 is connected to the third inlet 12-1 of the discharge tank 12 via a water supply pipeline. A third peristaltic pump 11 is installed on the water supply pipeline between the bottom left side of the pressure sensor 9 and the third inlet 12-1 of the discharge tank 12.

[0064] It should be noted that, Figure 6In the diagram, solid lines without dots represent water pipeline connection methods and operating procedures, while solid lines with dots represent electrical circuit connection methods and operating procedures.

[0065] Example 2

[0066] See Figure 7 The circulating in-situ ozone-PVDF hollow fiber ultrafiltration membrane shell filtration device of Example 1 was used to treat source water. It is important to understand that source water refers to drinking water, which is a natural water body and is a source of drinking water. During the treatment process, the influent was delivered to the PVDF hollow fiber ultrafiltration membrane filter unit, while ozone gas at a flow rate of 2.84 mg / L was simultaneously delivered to the PVDF hollow fiber ultrafiltration membrane filter unit at a flow rate of 0.4 L / min. The hydraulic retention time of the PVDF hollow fiber ultrafiltration membrane filter unit was 35 min, and the circulation flow rate was 30 mL / min. The filtration device of Example 1 operated continuously for 30 days. At the end of the operating cycle, the transmembrane pressure difference of the PVDF hollow fiber ultrafiltration membrane filter unit increased slowly, with an increment of 2.66 kPa. No flushing was performed during the operating cycle, and the internal membrane fouling of the PVDF hollow fiber ultrafiltration membrane filter unit was effectively controlled.

[0067] Comparative Example 2

[0068] See Figure 7 Water source was treated using the PVDF hollow fiber ultrafiltration membrane filtration device of Comparative Example 1. During the treatment process, the influent was delivered to the PVDF hollow fiber ultrafiltration membrane filtration unit, with a hydraulic retention time of 35 minutes. The filtration device of Comparative Example 1 operated continuously for 30 days. During the operating cycle, the transmembrane pressure difference of the PVDF hollow fiber ultrafiltration membrane filtration unit increased by an average of 11.5 kPa every 2-3 days. To restore the flux of the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane, 0.1 mol / L NaClO combined with 1 L / min air was used to flush the membrane fiber surface to remove contaminants for 10 minutes. Comparative Example 2 demonstrates that the membrane shell filtration unit composed of weakly hydrophilic PVDF hollow fiber ultrafiltration membranes without in-situ ozone coupling suffered from severe membrane fouling and required frequent flushing.

[0069] Example 3

[0070] See Figure 8The circulating in-situ ozone-PVDF hollow fiber ultrafiltration membrane shell filtration device described in Example 1 was used to treat source water. During the treatment process, influent was fed into the PVDF hollow fiber ultrafiltration membrane filter unit, while ozone gas at a flow rate of 2.84 mg / L was simultaneously fed into the PVDF hollow fiber ultrafiltration membrane filter unit at a flow rate of 0.4 L / min. The hydraulic retention time of the PVDF hollow fiber ultrafiltration membrane filter unit was 35 min, and the circulation flow rate was 30 mL / min. The device operated continuously for 30 days. At the end of the operating cycle, the PVDF hollow fiber ultrafiltration membrane filter unit reduced the COD in the source water... Mn The average removal rate was 20.42%, the average removal rate of turbidity was 100%, and the average removal rate of dissolved organic carbon was 14.97%.

[0071] Comparative Example 3

[0072] See Figure 8 The source water was treated using the PVDF hollow fiber ultrafiltration membrane filtration device described in Comparative Example 1. During the treatment process, the influent was fed into the PVDF hollow fiber ultrafiltration membrane filtration unit, where the hydraulic retention time was 35 minutes. The device operated continuously for 30 days. At the end of the operating cycle, the PVDF hollow fiber ultrafiltration membrane filtration unit reduced the COD in the source water. Mn The average removal rate was 6.58%, the average removal rate for turbidity was 100%, and the average removal rate for dissolved organic carbon was 7.66%.

[0073] Example 4

[0074] See Figure 9 and Figure 10 The circulating in-situ ozone-PVDF hollow fiber ultrafiltration membrane shell filtration device of Example 1 was used to treat source water. During the treatment process, influent water was delivered to the PVDF hollow fiber ultrafiltration membrane filtration unit, while ozone gas at a flow rate of 2.84 mg / L was simultaneously delivered to the PVDF hollow fiber ultrafiltration membrane filtration unit at a flow rate of 0.4 L / min. The hydraulic retention time of the PVDF hollow fiber ultrafiltration membrane filtration unit was 35 min, the circulation flow rate was 30 mL / min, and the device operated continuously for 30 days. At the end of the operating cycle, the average bubble point pressure of the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane in the PVDF hollow fiber ultrafiltration membrane filtration unit was 0.26 mPa, the average multi-bubble point pressure was 0.27 mPa, and the average breaking tensile force was 2194.5 cN.

[0075] Comparative Example 4

[0076] See Figure 9 and Figure 10Water source was treated using the PVDF hollow fiber ultrafiltration membrane filtration device described in Comparative Example 1. During the treatment process, the influent was fed into the PVDF hollow fiber ultrafiltration membrane filtration unit, where the hydraulic retention time was 35 minutes. The device operated continuously for 30 days. At the end of the operating cycle, the average bubble point pressure of the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane within the PVDF hollow fiber ultrafiltration membrane filtration unit was 0.26 mPa, the average multi-bubble point pressure was 0.27 mPa, and the average breaking tensile strength was 2215 cN.

[0077] Through the comparison of Example 2 and Comparative Example 2, Example 3 and Comparative Example 3, and Example 4 and Comparative Example 4, it can be seen that the filtration device of Example 1 adopts the construction of an external reaction unit, which is connected to the PVDF hollow fiber ultrafiltration membrane filtration unit, making full use of the ozone resistance characteristics of the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane; it makes up for the defect that the closed membrane shell filtration unit cannot introduce ozone in situ, and realizes the in situ introduction of ozone in the PVDF hollow fiber ultrafiltration membrane filtration unit to improve the ozone reaction efficiency and alleviate the membrane fouling of PVDF hollow fiber ultrafiltration membrane. The case study shows that when 2.84 mg / L ozone was introduced in situ into the PVDF hollow fiber ultrafiltration membrane unit of Example 1 at a circulation flow rate of 30 mL / min, after 30 days of operation, the transmembrane pressure difference increase of the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane was 2.66 kPa. The average removal rate of CODMn was 20.42%, the average removal rate of turbidity was 100%, and the average removal rate of dissolved organic carbon was 14.97%. There were no significant changes in the bubble point pressure and breaking tensile strength of the weakly hydrophilic PVDF hollow fiber membrane. In contrast, the filtration device in Comparative Example 1 was significantly less effective than that in Example 1.

[0078] In summary, the circulating in-situ ozone-PVDF hollow fiber ultrafiltration membrane shell filtration device of the present invention has been tested and verified in actual water treatment. The present invention can effectively alleviate the membrane fouling problem of the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane in the PVDF hollow fiber ultrafiltration membrane filtration unit, improve the quality of the produced water, and the physicochemical properties of the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane are not damaged.

[0079] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0080] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A filtration device for water treatment, characterized in that, The system includes an inlet water unit, an external reaction unit (5), a PVDF hollow fiber ultrafiltration membrane filtration unit (4), an ozone preparation and control unit, a transmembrane pressure difference detection and recording unit, and a product water storage unit. The external reaction unit (5) is located between the inlet water unit and the PVDF hollow fiber ultrafiltration membrane filtration unit (4). The ozone preparation and control unit is connected to the PVDF hollow fiber ultrafiltration membrane filtration unit (4). The inlet water unit is an inlet water tank (8), and the top of the inlet water tank (8) is... The external reaction unit (5) is equipped with a first inlet (8-1) and a first outlet (8-2); the external reaction unit (5) includes an ozone exhaust port (5-1), a second circulation interface (5-2), a sealing cover (5-3), an overflow port (5-4), a second inlet (5-5), and a first circulation interface (5-6). The ozone exhaust port (5-1) and the second circulation interface (5-2) are located on the top of the sealing cover (5-3); the second inlet (5-5) is connected to the first outlet (8-6) via a water supply pipeline. The water inlet (8-2) is connected, and a second peristaltic pump (7) and a third valve (15) are installed on the water supply pipeline between the second water inlet (5-5) and the first water outlet (8-2). The overflow port (5-4) is connected to the first water outlet (8-2) through another water supply pipeline. The PVDF hollow fiber ultrafiltration membrane filtration unit (4) includes a second water outlet (4-1), a fourth circulation interface (4-3), a weakly hydrophilic PVDF hollow fiber ultrafiltration membrane (4-4), and a third circulation interface (4- 5) Ozone aeration holes (4-8), the third circulation interface (4-5) is connected to the first circulation interface (5-6) through a water supply pipeline, a first peristaltic pump (6) and a fourth valve (16) are installed on the water supply pipeline between the third circulation interface (4-5) and the first circulation interface (5-6), the fourth circulation interface (4-3) is connected to the second circulation interface (5-2) through another water supply pipeline, and the contact angle of the weakly hydrophilic PVDF hollow fiber ultrafiltration membrane (4-4) is 80°. ~ 90°; The ozone preparation and control unit includes an air pump (1), a gas rotor flow meter (2) and an ozone generator (3) connected in sequence via a gas pipeline. The outlet of the ozone generator (3) is connected to the ozone aeration hole (4-8) via a gas pipeline. A fifth valve (17) is provided on the gas pipeline between the outlet of the ozone generator (3) and the ozone aeration hole (4-8). The transmembrane pressure difference detection and recording unit includes a pressure sensor (9) and a paperless recorder (10) electrically connected to the pressure sensor (9). One end of the pressure sensor (9) is connected to the second water outlet (4-1) via a water supply pipeline. The other end of the pressure sensor (9) is connected to the third peristaltic pump (11) via a water supply pipeline.

2. The filtration device according to claim 1, characterized in that, The overflow port (5-4) is located on the upper side of the external reaction unit (5), the second inlet (5-5) is located on the middle side of the external reaction unit (5), and the first circulation port (5-6) is located on the lower side of the external reaction unit (5).

3. The filtration device according to claim 1, characterized in that, The PVDF hollow fiber ultrafiltration membrane filtration unit (4) includes a sealing partition (4-2), an aeration hole (4-6), an air flushing inlet (4-7), a concentrate outlet (4-9), and a perforated sealing partition (4-10).

4. The filtration device according to claim 3, characterized in that, The fourth circulation port (4-3) is located on the upper side of the PVDF hollow fiber ultrafiltration membrane filter unit (4), the third circulation port (4-5) is located on the lower side of the PVDF hollow fiber ultrafiltration membrane filter unit (4), the air flushing inlet (4-7), the ozone aeration port (4-8) and the concentrate outlet (4-9) are all located at the bottom of the PVDF hollow fiber ultrafiltration membrane filter unit (4), and the second outlet (4-1) is located at the top of the PVDF hollow fiber ultrafiltration membrane filter unit (4).

5. The filtration device according to claim 3, characterized in that, The weakly hydrophilic PVDF hollow fiber ultrafiltration membrane (4-4) has an average pore size of 0.02 μm and a porosity of 70% to 80%.

6. The filtration device according to claim 1, characterized in that, The water production storage unit is a discharge tank (12). The top of the discharge tank (12) is provided with a third water inlet (12-1) and a third water outlet (12-2). The third water inlet (12-1) is connected to the third peristaltic pump (11) through a water supply pipeline.

Images