Modified PVDF (Polyvinylidene Fluoride) tubular filter membrane and reclaimed water advanced treatment filter system applying same

Abstract

The invention belongs to the technical field of reclaimed water advanced treatment, and particularly relates to a modified PVDF (polyvinylidene fluoride) tubular filter membrane and a reclaimed water advanced treatment filter system applying the modified PVDF tubular filter membrane, the modified PVDF tubular filter membrane comprises a purification tank, two-stage membrane filtration equipment, an adsorption filtration device and a disinfection PH (potential of hydrogen) regulation tank which are sequentially connected through a connecting pipeline, and the disinfection PH regulation tank is connected with a water outlet pipe; a pressure pump and a valve are arranged on each connecting pipeline, the PVDF tubular filter membrane comprises the following raw materials in percentage by mass: 16-18% of PVDF, 4-5% of calcined zeolite, 2-3% of calcined bentonite, 1-2% of calcined shale ultrafine powder and 72-75% of a solvent, and the solvent is one of NMP or DMF. According to the system, through multi-stage filtration, specifically, the modified PVDF tubular filtration membrane is adopted for treating suspended matters, colloids, bacteria, macromolecular organic matters and heavy metal ions, and soluble organic matters, peculiar smell, chromaticity and trace pollutants can be removed through the system, so that discharged reclaimed water can meet the three-stage standard of surface water.

Description

Technical Field

[0001] The present invention relates to the technical field of deep treatment of reclaimed water, in particular to a modified PVDF tubular filter membrane and a deep treatment filtration system of reclaimed water using the same. Background Art

[0002] With the acceleration of urbanization and the growth of population, the discharge of water treatment, especially sewage treatment, has been increasing year by year. Although traditional sewage treatment processes, such as activated sludge process and oxidation ditch, can effectively remove most organic matter and suspended solids, the effluent quality is usually difficult to meet the increasingly stringent emission standards or the demand for reclaimed water reuse. Residual pollutants in domestic sewage (such as colloids, pathogenic microorganisms, trace organic matter and some soluble pollutants) have become a key bottleneck restricting the improvement of water quality. In such an environment, deep treatment technology has gradually become a hot spot for research and application. Therefore, the existing technology has gradually begun to study the use of ultrafiltration membranes for deep treatment of reclaimed water. However, ultrafiltration membranes remove suspended matter, colloids, bacteria and macromolecular organic matter in water through physical interception, and have high-efficiency separation performance. However, ultrafiltration membranes do not have adsorption effects.

[0003] Therefore, the application of ultrafiltration membranes in the deep treatment of reclaimed water has begun to be developed in the prior art. However, the treatment effect of ultrafiltration membranes in the prior art often fails to meet the discharge standards or the requirements of high-quality water.

[0004] Therefore, based on the above technical problems, a modified PVDF tubular filter membrane and a reclaimed water deep treatment filtration system using the same were designed. Summary of the Invention

[0005] In order to make up for the problem that the membrane treatment effect in the prior art often fails to meet the emission standards, the present invention proposes a modified PVDF tubular filter membrane and a reclaimed water deep treatment filtration system using the same.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A modified PVDF tubular filter membrane comprises the following raw materials by mass percentage: 16% to 18% PVDF, 4% to 5% calcined zeolite, 2% to 3% calcined bentonite, 1% to 2% calcined shale ultrafine powder, and 72% to 75% solvent, wherein the solvent is one of NMP and DMF.

[0008] Principle: PVDF matrix material provides mechanical strength, calcined zeolite core modifier improves flux and hydrophilicity, calcined bentonite enhances pollutant adsorption capacity, calcined shale ultrafine powder reduces cost and improves thermal stability, and solvent dissolves PVDF to form a homogeneous casting solution;

[0009] Preferably, 4% to 5% PEG is added by mass to adjust the pore structure.

[0010] The PVDF tubular filter membrane preparation process includes the following steps:

[0011] 1. Preparation of materials:

[0012] (1) calcining zeolite, bentonite and shale ultrafine powder at 800-1000°C to form calcined zeolite, calcined bentonite and calcined shale ultrafine powder;

[0013] (2) using an ultrafine ball mill to grind the calcined zeolite, calcined bentonite, and calcined shale ultrafine powders to a particle size of ≤1 μm;

[0014] (3) Dry the PVDF particles at 80°C for 4 h;

[0015] 2. Preparation of PVDF tubular filter membrane:

[0016] (1) Preparation of casting solution:

[0017] PVDF 16-18%, calcined zeolite 4%-5%, calcined bentonite 2%-3%, calcined shale ultrafine powder 1%-2%, solvent 72%-75%, PEG 4%-5% were mixed by mass percentage, and stirred at 60°C for 6 hours until homogeneous. The viscosity of the casting solution was 2500-3500 cP.

[0018] (2) Degassing: let it stand for 24 hours or vacuum degassing;

[0019] (3) Scraping film: Scraping on a glass plate to form a 200-300 μm thick liquid film;

[0020] (4) Coagulation bath: immerse in pure water for phase inversion molding, the temperature is 20±2°C;

[0021] (5) Post-treatment: rinsing with pure water, moisturizing with glycerin, and drying at 60°C.

[0022] A reclaimed water deep treatment filtration system using the modified PVDF tubular filtration membrane comprises a purification tank, a two-stage membrane filtration device, an adsorption filtration device, and a disinfection and pH adjustment tank connected in sequence through connecting pipes, wherein the disinfection and pH adjustment tank is connected to a water outlet pipe, and the connecting pipes are all provided with a pressure pump and a valve;

[0023] The dual-stage membrane filtration device includes multiple groups of filtration devices, each of which includes a housing and multiple groups of modified PVDF tubular filtration membranes disposed inside the housing. The modified PVDF tubular filtration membranes form a tubular filtration membrane cavity. Recycled water passes through the modified PVDF tubular filtration membrane from the housing and enters the filtration membrane cavity. The filtration membrane cavity is provided with a filtration outlet. The filtered recycled water is discharged from the filtration outlet to the adsorption filtration device.

[0024] The adsorption and filtration device is filled with an inorganic adsorption material, and the reclaimed water is filtered through the inorganic adsorption material and discharged into a disinfection and pH adjustment pool;

[0025] The disinfection and pH adjustment tank is used to disinfect the reclaimed water discharged from the adsorption and filtration device and adjust the pH value;

[0026] The pore size of the modified PVDF tubular filter membrane is 0.01-0.1 μm, and the modified PVDF tubular filter membrane has an adsorption and filtration function.

[0027] Preferably, the cleaning pool includes a placement pool, which is divided into a filter pool and a water outlet pool. A baffle is provided between the filter pool and the water outlet pool. An opening is provided at the lower end of the baffle, and the opening connects the filter pool and the water outlet pool. The water outlet pool is connected to a two-stage membrane filtration device. A filter screen is provided in the middle of the filter pool, and an inorganic filter material is provided in the filter screen.

[0028] Working principle: This application conducts deep treatment of reclaimed water through 4 steps, namely water inlet - pretreatment - modified PVDF tubular filter membrane filtration - inorganic material adsorption - final disinfection and pH value adjustment - water outlet. Specifically: the reclaimed water is removed from suspended solids in the purification tank by coagulation sedimentation filtration, and then the modified PVDF tubular filter membrane is used to remove microorganisms and heavy metal ions, and then the dissolved organic matter, odor, color and trace pollutants are removed by inorganic materials; finally, the reclaimed water is discharged after disinfection and pH value adjustment. The disinfection can be ultraviolet disinfection or sodium hypochlorite disinfection. Multi-stage disinfection makes the reclaimed water discharged by this application meet the surface water discharge standard of Class III.

[0029] Preferably, a flushing device is provided on the outside of the filter membrane cavity, and the flushing device includes a plurality of annular flushing pipes arranged on the outside of the filter cavity, and the plurality of annular flushing pipes are connected by connecting pipes, and the connecting pipes are connected to a water source. The annular flushing pipes are provided with a plurality of flushing holes, and the flushing holes are aligned with the modified PVDF tubular filter membrane. A waste outlet is provided at the bottom of the shell, and a waste valve is provided at the waste outlet, so that the multiple filter membranes can be cleaned conveniently without disassembly, thereby avoiding blockage of the modified PVDF tubular filter membrane due to microorganisms and the like, affecting the filtration efficiency.

[0030] Preferably, the flushing water sprayed from the flushing hole forms an angle of 30° to 45° with the modified PVDF tubular filter membrane, thereby ensuring a wider flushing range while ensuring flushing pressure on the modified PVDF tubular filter membrane.

[0031] Preferably, the inorganic filter material provided in the filter screen is ceramsite, and the inorganic adsorption material filled in the adsorption filtration device is activated carbon.

[0032] Preferably, the adsorption and filtration device includes multiple groups of adsorption devices, and the adsorption device includes a frame and multiple filter tubes arranged on the frame. The filter tubes are filled with inorganic adsorption materials, and the reclaimed water is filtered through the inorganic adsorption materials in the filter tubes.

[0033] Preferably, the filter tube and the frame are detachably connected, each filter tube is provided with a filter tube outlet pipe and a filter tube inlet pipe, each filter tube inlet pipe is provided with a water inlet valve, and each filter tube outlet pipe is provided with a water outlet valve.

[0034] The present invention is beneficial in that:

[0035] 1. The present invention uses multi-stage filtration, specifically using modified PVDF tubular filter membranes to remove suspended matter, colloids, bacteria, macromolecular organic matter and heavy metal ions, and removes dissolved organic matter, odor, color and trace pollutants through modified PVDF membrane filtration and physical adsorption and biodegradation, so that the discharged reclaimed water can meet the standards. At the same time, a pre-adsorption of colloid substances is provided to reduce membrane pollution.

[0036] 2. A flushing device is provided on the outside of the filter membrane cavity of the present invention, and the flushing device includes a plurality of circular flushing pipes arranged on the outside of the filter cavity. The plurality of circular flushing pipes are connected by a connecting pipe, and the connecting pipe is connected to a water source. A plurality of flushing holes are provided on the circular flushing pipe, and the flushing holes are aligned with the modified PVDF tubular filter membrane. A waste outlet is provided at the bottom of the shell, and a valve is provided at the waste outlet, so that the filter membrane can be cleaned conveniently without disassembly, thereby avoiding blockage of the modified PVDF tubular filter membrane due to microorganisms and the like, affecting the filtration efficiency.

[0037] 3. The filter tubes of the present invention are detachably connected to the frame, and each filter tube is provided with a filter tube outlet pipe and a filter tube inlet pipe. Each filter tube inlet pipe is provided with a water inlet valve, and each filter tube outlet pipe is provided with a water outlet valve, so that each filter tube can be replaced individually without affecting the operation of the entire machine.

[0038] 4. The modified PVDF tubular filter membrane of the present invention has filtering and adsorption functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 It is a schematic diagram of the structure of the present invention;

[0041] Figure 2 It is a structural schematic diagram of the double-stage membrane filtration device of the present invention;

[0042] Figure 3 It is a structural schematic diagram of the double-stage membrane filtration device of the present invention;

[0043] Figure 4 It is a structural schematic diagram of the vertical pole of the adsorption and filtration device of the present invention.

[0044] In the figure: 1. Purification tank; 2. Two-stage membrane filtration equipment; 3. Adsorption filtration device; 4. Disinfection and pH adjustment tank; 5. Pressure pump; 6. Valve; 7. Flushing equipment; 8. Waste outlet; 101. Filter tank; 102. Outlet tank; 103. Baffle; 104. Filter screen; 201. Shell; 202. Modified PVDF tubular filter membrane; 301. Frame; 302. Filter tube; 701. Flushing tube. DETAILED DESCRIPTION

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0046] Equipment required for this application:

[0047] High-temperature calcining furnace: Model: SX2-12-16N; Supplier: Shanghai Yiheng; Conditions: Maximum calcining temperature 1200°C, controllable heating rate 10°C / min;

[0048] Ultrafine ball mill: Model: QM-3SP4; Supplier: Nanjing University Instrument Factory; Conditions: Discharge particle size ≤ 1 μm, processing capacity 5 kg / h;

[0049] Vacuum drying oven: Model: DZF-6050; Supplier: Shanghai Jinghong; Conditions: 60L volume, room temperature ~ 250℃;

[0050] Constant temperature mixer: Model: JJ-1B; Supplier: Changzhou Jintan; Conditions: Speed 0-3000 rpm, temperature control ±1°C;

[0051] Automatic film scraping machine: Model: MSK-AFA-200; Supplier: Shenzhen Kejing; Requirements: Scraper accuracy ±5μm, substrate width 200mm;

[0052] Phase inversion coagulation tank: Material: stainless steel; Dimensions: 500×300×200mm; Supplier: Wuxi Chemical Equipment Factory; Conditions: With temperature control system;

[0053] raw material:

[0054] PVDF: Supplier Shanghai Dongfu Chemical Technology Co., Ltd., brand J-1,

[0055] Example 1:

[0056] The specific implementation method for preparing the modified PVDF tubular filter membrane is as follows:

[0057] The PVDF tubular filter membrane preparation process includes the following steps:

[0058] 1. Preparation of materials:

[0059] (1) calcining zeolite, bentonite and shale ultrafine powder in a high temperature calcining furnace at 800° C. to form calcined zeolite, calcined bentonite and calcined shale ultrafine powder;

[0060] (2) using an ultrafine ball mill to grind the calcined zeolite, calcined bentonite, and calcined shale ultrafine powders to a particle size of ≤1 μm;

[0061] (3) Place the PVDF particles in a vacuum drying oven at 80°C and dry for 4 h;

[0062] 2. Preparation of PVDF tubular filter membrane:

[0063] (1) Preparation of casting solution:

[0064] 16% PVDF, 4% calcined zeolite, 3% calcined bentonite, 1% calcined shale ultrafine powder, 72% DMF solvent, and 4% PEG-400 were mixed by mass percentage, and stirred in a constant temperature mixer at 60° C. for 6 h until a homogeneous phase was obtained. The viscosity of the casting solution was 2600 cP.

[0065] (2) Degassing: let it stand for 24 hours or vacuum degassing;

[0066] (3) Scraping film: A 200 μm thick liquid film was scraped on a glass plate using an automatic scraping machine;

[0067] (4) Coagulation bath: The thick liquid film is immersed in a phase inversion coagulation tank filled with pure water for phase inversion molding;

[0068] (5) Post-treatment: rinsing with pure water, moisturizing with glycerin, and drying at 60°C.

[0069] Example 2:

[0070] The specific implementation method for preparing the modified PVDF tubular filter membrane is as follows:

[0071] The PVDF tubular filter membrane preparation process includes the following steps:

[0072] 1. Preparation of materials:

[0073] (1) calcining zeolite, bentonite and shale ultrafine powder at 900°C to form calcined zeolite, calcined bentonite and calcined shale ultrafine powder;

[0074] (2) using an ultrafine ball mill to grind the calcined zeolite, calcined bentonite, and calcined shale ultrafine powders to a particle size of ≤1 μm;

[0075] (3) Dry the PVDF particles at 80°C for 4 h;

[0076] 2. Preparation of PVDF tubular filter membrane:

[0077] (1) Preparation of casting solution:

[0078] PVDF 17%, calcined zeolite 4.5%, calcined bentonite 2.5%, calcined shale ultrafine powder 1.5%, solvent NMP 72%, PEG 4.5% were mixed by mass percentage, stirred at 60°C for 6 hours until homogeneous, and the viscosity of the casting solution was 3000 cP;

[0079] (2) Degassing: let it stand for 24 hours or vacuum degassing;

[0080] (3) Scraping film: Scraping a 250 μm thick liquid film on a glass plate;

[0081] (4) Coagulation bath: immerse in pure water for phase inversion molding, the temperature is 20±2°C;

[0082] (5) Post-treatment: rinsing with pure water, moisturizing with glycerin, and drying at 60°C.

[0083] Example 3:

[0084] The specific implementation method for preparing the modified PVDF tubular filter membrane is as follows:

[0085] The PVDF tubular filter membrane preparation process includes the following steps:

[0086] 1. Preparation of materials:

[0087] (1) calcining zeolite, bentonite and shale ultrafine powder at 900°C to form calcined zeolite, calcined bentonite and calcined shale ultrafine powder;

[0088] (2) using an ultrafine ball mill to grind the calcined zeolite, calcined bentonite, and calcined shale ultrafine powders to a particle size of ≤1 μm;

[0089] (3) PVDF particles were dried at 80°C for 4 h;

[0090] 2. Preparation of PVDF tubular filter membrane:

[0091] (1) Preparation of casting solution:

[0092] PVDF 18%, calcined zeolite 5%, calcined bentonite 3%, calcined shale ultrafine powder 2%, solvent NMP 75%, PEG 5% were mixed by mass percentage, stirred at 60 ° C for 6 hours until homogeneous, and the viscosity of the casting solution was 2500-3500 cP;

[0093] (2) Degassing: let it stand for 24 hours or vacuum degassing;

[0094] (3) Scraping film: Scraping on a glass plate to form a 200-300 μm thick liquid film;

[0095] (4) Coagulation bath: immerse in pure water for phase transformation and molding;

[0096] (5) Post-treatment: rinsing with pure water, moisturizing with glycerin, and drying at 60°C.

[0097] Specific implementation method: Take the modified PVDF tubular filter membrane prepared in Example 2 and set up the two-stage membrane filtration equipment as follows:

[0098] See also Figures 1 to 4 A modified PVDF tubular filtration and adsorption system for deep treatment of reclaimed water is shown, comprising a purification tank 1, a two-stage membrane filtration device 2, an adsorption filtration device 3, and a disinfection and pH adjustment tank 4, which are sequentially connected by connecting pipes. The disinfection and pH adjustment tank 4 is connected to a water outlet pipe, and the connecting pipes are each provided with a pressure pump 5 and a valve 6.

[0099] The dual-stage membrane filtration device includes two groups of filtration devices, each of which includes a housing 201 and six groups of modified PVDF tubular filter membranes 202 arranged inside the housing 201. The modified PVDF tubular filter membranes 202 are installed in the housing 201 through mounting brackets arranged at both ends of the modified PVDF tubular filter membranes 202. The modified PVDF tubular filter membranes 202 are rolled into a cylindrical shape to form a hollow tubular filter membrane cavity. The modified PVDF tubular filter membrane 202 is installed in the housing 201 through mounting brackets arranged at both ends of the modified PVDF tubular filter membrane 202. The filter membrane cavity is provided with a filter outlet, and the filtered reclaimed water is discharged from the filter outlet to the adsorption filter device 3.

[0100] The adsorption and filtration device 3 includes two groups of adsorption devices, each of which includes a frame 301 and six filter tubes 302 arranged on the frame 301. The filter tubes 302 are filled with activated carbon material. The reclaimed water is filtered through the inorganic adsorption material in the filter tubes 302. The reclaimed water is filtered from the inorganic adsorption material and discharged into the disinfection pH adjustment pool 4.

[0101] The disinfection and pH adjustment tank 4 is used to disinfect the reclaimed water discharged from the adsorption and filtration device 3 and adjust the pH value;

[0102] The pore size of the modified PVDF tubular filter membrane 202 is 0.01 to 0.1 μm, and the modified PVDF tubular filter membrane 202 has an adsorption and filtration function.

[0103] The cleaning pool 1 includes a placement pool, which is divided into a filter pool 101 and a water outlet pool 102. A baffle 103 is provided between the filter pool 101 and the water outlet pool 102. The lower end of the baffle 103 is provided with an opening, which connects the filter pool 101 and the water outlet pool 102. The water outlet pool 102 is connected with the two-stage membrane filtration device 2. A filter screen 104 is provided in the middle position of the filter pool 101, and ceramsite is provided in the filter screen 104. The filter screen 104 is provided with ceramsite. The baffle 103 divides the placement pool into the filter pool 101 and the water outlet pool 102, and a notch is provided at the bottom. The reclaimed water passes through the ceramsite and enters the water outlet pool 102 through the pressure problem, forming the first step of filtration. The filter screen 104 is hooked to the filter pool 101, so that it is convenient to directly remove the filter screen 104 from the filter pool 101 and replace the ceramsite.

[0104] In another embodiment: a flushing device 7 is provided on the outside of the filter membrane cavity, and the flushing device 7 includes a plurality of circular flushing pipes 701 arranged on the outside of the filter cavity, and the plurality of circular flushing pipes 701 are connected by a connecting pipe, and the connecting pipe is connected to a water source. The circular flushing pipe 701 is provided with a plurality of flushing holes, and the flushing holes are aligned with the modified PVDF tubular filter membrane 202. A waste outlet 8 is provided at the bottom of the shell 201, and a waste valve 6 is provided at the waste outlet 8, so that the multiple filter membranes can be cleaned conveniently without disassembly, thereby avoiding blockage of the modified PVDF tubular filter membrane 202 due to microorganisms and the like, affecting the filtration efficiency.

[0105] In another embodiment: the waste valve 6 is a solenoid valve, each of the filter chambers is connected to a water outlet pipe, and the water outlet pipes are provided with a flow meter. A lower water level gauge is provided inside the shell 201, and the lower water level gauge is set at the lowest end of the lowest filter membrane chamber. A PLC controller is provided on the shell 201, and the PLC controller is electrically connected to the lower water level gauge, the solenoid valve and the flushing device. The condition of the filter membrane is monitored by the flow meter. If the flow meter shows that the flow rate is less than the normal value, it proves that the filter membrane needs to be cleaned. When the PLC controller detects that the value of the flow meter is lower than the normal value, the water supply is stopped, the PLC controller opens the solenoid valve, and drains the water. When the water level reaches the lower water level gauge, the solenoid valve is closed, and the PLC controller opens the solenoid valve 2 to control the flushing device to run for cleaning. After the cleaning is completed, the flushing device is closed, and water continues to flow into the shell 201 for continued filtration.

[0106] In another embodiment, the flushing water sprayed from the flushing hole forms an angle of 30° to 45° with the modified PVDF tubular filter membrane 202 to ensure a wider flushing range while ensuring flushing pressure on the modified PVDF tubular filter membrane 202.

[0107] In another embodiment, the filter tube 302 and the frame 301 are detachably connected, each of the filter tubes 302 is provided with a filter tube 302 outlet pipe and a filter tube 302 inlet pipe, each of the filter tube 302 inlet pipes is provided with a water inlet valve 6, and each of the filter tube 302 outlet pipes is provided with a water outlet valve 6.

[0108] Actual filtration operation: First, the reclaimed water that needs to be deeply treated is placed in the filter pool 101. The reclaimed water flows through the gap at the bottom due to the pressure pump 5 and its own gravity, and then enters the two-stage membrane filtration device. The reclaimed water fills the shell 201. The shell 201 forms a positive pressure through the pressure pump 5 to squeeze the reclaimed water in the shell 201 into the filter membrane cavity to form the second step of filtration, and then enters the filter tube 302 in the adsorption filtration device 3, so that the reclaimed water passes through the activated carbon in the filter tube 302, forming the third step of filtration. After the filtration is completed, it passes through the disinfection and pH adjustment pool 4, is ultraviolet disinfected and the pH value is adjusted before being discharged.

[0109] Since a multi-stage filtration device and an adsorption filtration device 3 can be designed according to the water quality and water quality requirements, the actual device in this embodiment has two sets of filtration devices, that is, after filtering through the filtration membrane cavity twice, adsorption filtration is continued, and the adsorption device is also two sets of devices, so that two filtrations can be performed, thereby improving the filtration effect.

[0110] Comparative Example:

[0111] Comparative Example 1: The reclaimed water to be treated is filtered through a conventional MBR filter membrane;

[0112] Comparative Example 2: The reclaimed water to be treated is filtered through a sand filter and then through an ultrafiltration membrane to achieve double-stage filtration.

[0113] The following table shows the "Water Quality of Industrial Water for Urban Wastewater Recycling" (GB / T19923-2005). This standard clearly stipulates the water quality limits for recycled water used for industrial purposes (including process water, product processing water, etc.). The main indicators are as follows:

[0114]

[0115]

[0116] Comparing the system in this application with the comparative example and comparative example 2, the following data can be obtained:

[0117] 1. At 1000m 3 The pilot scale was run continuously for 90 days and the effluent quality was as follows:

[0118]

[0119] 2. Shock load resistance test (influent COD suddenly increases to 500mg / L)

[0120] Flux recovery time COD effluent stability This application 2 hours 15±3mg / L Comparative Example 1 12 hours 80~120mg / L Comparative Example 2 Immediate blockage Exceeding the standard shutdown

[0121] 3. Comparison of annual operating costs (unit: 10,000 yuan / year)

[0122]

[0123] 4. Economical efficiency The present application is compared with Comparative Example 2 as follows:

[0124]

[0125] It can be concluded from Tables 1 and 2 above that the water quality filtered by the system in the present application is much higher than that of Example 1 and Comparative Example 2. The reclaimed water treated by the system in the present application can reach the third-level surface reclaimed water, that is, high-quality reclaimed water. At the same time, the shock load resistance test in Table 2 can show that the system of the present application is far superior to Comparative Example 1 and Comparative Example 2 in terms of flux recovery time and COD effluent stability. Comparative Example 2 even has a stronger shock load resistance than the test strength.

[0126] Table 3 provides a comparison of annual operating costs. The annual operating costs in this application are significantly lower than those in Comparative Example 2 and appear to be comparable to those in Comparative Example 3. However, Table 4 shows that the payback period for investment costs is significantly shorter than that in Comparative Example 2. Furthermore, since the filtered water in this application is of high quality, it can be sold to high-end users, generating a profit.

[0127] At the same time, from the perspective of lifespan, the average lifespan of the modified PVDF tubular filter membrane in this application is 5 years, while the average lifespan of the ultrafiltration membrane and the traditional MBR filter membrane is 2.5 years. The service life of this application is much longer than that of Comparative Example 1 and Comparative Example 2. At the same time, in Comparative Example 2, sand filtration backwashing will be performed during the cleaning process, which will cause a loss of about 5% water production rate. At the same time, the filtration system of this application can be used for deep treatment of municipal reclaimed water, and has a wide range of applications.

[0128] Therefore, in summary, the system of this application is far superior to the equipment for deep treatment of reclaimed water on the market in terms of filtered water quality and economic value.

[0129] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these 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 any one or more embodiments or examples.

[0130] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A modified PVDF tubular filter membrane, characterized in that: The PVDF tubular filter membrane comprises the following raw materials by mass percentage: 16% to 18% of PVDF, 4% to 5% of calcined zeolite, 2% to 3% of calcined bentonite, 1% to 2% of calcined shale ultrafine powder, and 72% to 75% of solvent, wherein the solvent is one of NMP and DMF.

2. The modified PVDF tubular filter membrane according to claim 1, characterized in that: Add 4% to 5% PEG by mass.

3. The modified PVDF tubular filter membrane according to claim 1, characterized in that: The PVDF tubular filter membrane preparation process includes the following steps:

1. Preparation of materials: (1) calcining zeolite, bentonite and shale ultrafine powder at 800-1000°C to form calcined zeolite, calcined bentonite and calcined shale ultrafine powder; (2) using an ultrafine ball mill to grind the calcined zeolite, calcined bentonite, and calcined shale ultrafine powders to a particle size of ≤1 μm; (3) Dry the PVDF particles at 80°C for 4 h; 2. Preparation of PVDF tubular filter membrane: (1) Preparation of casting solution: PVDF 16-18%, calcined zeolite 4%-5%, calcined bentonite 2%-3%, calcined shale ultrafine powder 1%-2%, solvent 72%-75%, PEG 4%-5% were mixed by mass percentage, and stirred at 60°C for 6 hours until homogeneous. The viscosity of the casting solution was 2500-3500 cP. (2) Degassing: let it stand for 24 hours or vacuum degassing; (3) Scraping film: Scraping on a glass plate to form a 200-300 μm thick liquid film; (4) Coagulation bath: immerse in pure water for phase inversion molding, the temperature is 20±2°C; (5) Post-treatment: rinsing with pure water, moisturizing with glycerin, and drying at 60°C.

4. A reclaimed water deep treatment filtration system using a modified PVDF tubular filtration membrane as claimed in claim 1, characterized in that: The invention comprises a cleaning pool (1), a two-stage membrane filtration device (2), an adsorption filtration device (3) and a disinfection and pH adjustment pool (4) which are sequentially connected through connecting pipes. The disinfection and pH adjustment pool (4) is connected to a water outlet pipe, and the connecting pipes are each provided with a pressure pump (5) and a valve (6); The two-stage membrane filtration device (2) comprises a plurality of filtration devices, the filtration devices comprising a housing (201) and a plurality of modified PVDF tubular filtration membranes (202) arranged inside the housing (201), the modified PVDF tubular filtration membranes (202) forming a tubular filtration membrane cavity, the reclaimed water passing through the modified PVDF tubular filtration membrane (202) from the housing (201) entering the filtration membrane cavity, the filtration membrane cavity being provided with a filtration outlet, and the filtered reclaimed water being discharged from the filtration outlet to the adsorption filtration device (3); The adsorption and filtration device (3) is filled with an inorganic adsorption material, and the reclaimed water is filtered through the inorganic adsorption material and discharged into the disinfection and pH adjustment pool (4); The disinfection and pH adjustment pool (4) is used to disinfect the reclaimed water discharged from the adsorption and filtration device (3) and to adjust the pH value; The pore size of the modified PVDF tubular filter membrane (202) is 0.01 to 0.1 μm, and the modified PVDF tubular filter membrane (202) has the function of filtering and adsorbing suspended matter, colloids, bacteria, macromolecular organic matter and heavy metal ions.

5. The deep treatment and filtration system for reclaimed water according to claim 4, characterized in that: The purification pool (1) comprises a filter pool (101) and a water outlet pool (102); a baffle (103) is provided between the filter pool (101) and the water outlet pool (102); an opening is provided at the lower end of the baffle (103); the opening connects the filter pool (101) and the water outlet pool (102); the water outlet pool (102) is connected to the two-stage membrane filtration device (2); a filter screen (104) is provided in the middle of the filter pool (101); an inorganic filter material is provided in the filter screen (104).

6. The reclaimed water deep treatment filtration system according to claim 4, characterized in that: A flushing device (7) is provided on the outside of the filter membrane cavity, and the flushing device (7) includes a plurality of circular flushing pipes (701) arranged on the outside of the filter cavity. The plurality of flushing pipes (701) are connected to each other through a connecting pipe, and the connecting pipe is connected to a water source. The circular flushing pipe (701) is provided with a plurality of flushing holes, and the flushing holes are aligned with the modified PVDF tubular filter membrane (202). A waste outlet (8) is provided at the bottom of the shell (201), and a waste outlet valve is provided at the waste outlet.

7. The reclaimed water deep treatment filtration system according to claim 6, characterized in that: The flushing water sprayed from the flushing hole forms an angle of 30° to 45° with the modified PVDF tubular filter membrane (202).

8. The reclaimed water deep treatment filtration system according to claim 5, characterized in that: The inorganic filter material provided in the filter screen (104) is ceramsite, and the inorganic adsorption material filled in the adsorption filter device (3) is activated carbon.

9. The reclaimed water deep treatment filtration system according to claim 4, characterized in that: The adsorption filtering device (3) comprises a plurality of adsorption devices, wherein the adsorption device comprises a frame (301) and a plurality of filter tubes (302) arranged on the frame (301), wherein the filter tubes are filled with inorganic adsorption materials, and the reclaimed water is filtered through the inorganic adsorption materials in the filter tubes (302).

10. The reclaimed water deep treatment filtration system according to claim 9, characterized in that: The filter tube (302) and the frame (301) are detachably connected. Each filter tube (302) is provided with a filter tube outlet pipe and a filter tube inlet pipe. Each filter tube inlet pipe is provided with a water inlet valve, and each filter tube outlet pipe is provided with a water outlet valve.

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