JP3887072B2

JP3887072B2 - Method for cleaning hollow fiber membrane module and filtration device used in the method

Info

Publication number: JP3887072B2
Application number: JP16116697A
Authority: JP
Inventors: 勤三浦; 正志小林; 愼次小森
Original assignee: 株式会社クラレ
Priority date: 1997-02-12
Filing date: 1997-06-18
Publication date: 2007-02-28
Anticipated expiration: 2017-06-18
Also published as: JPH10286441A

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for cleaning a hollow fiber membrane module and a filtration device used in the method.
[0002]
[Prior art]
In recent years, the development of separation technology using hollow fiber membranes has progressed, and it is widely used for various applications including water filtration. However, in the process of filtration with a hollow fiber membrane, solid substances such as suspended solids in a stock solution called SS adhere to the surface of the hollow fiber membrane or penetrate into the microporous membrane, and the permeation flux decreases with time. . Therefore, in order to continue the filtration operation stably for a long time, it is indispensable to develop a method for cleaning the hollow fiber membrane that is effective at the same time as setting the filtration conditions.
[0003]
Conventionally, various methods have been studied as a method for cleaning a hollow fiber membrane module, and these can be roughly classified into a physical cleaning method and a chemical cleaning method. Physical cleaning methods include a method of forcibly removing adhering substances with a sponge ball, high-pressure water flow, etc., a liquid back-washing method in which liquid such as water and permeate is passed from the filtrate side to the stock solution side, and pressurized gas as filtrate. Gas back-washing method (see JP-A-53-108882, JP-A-1-5000732, etc.), bubbling method in which bubbles are ejected to the stock solution side, ultrasonic method, electrophoresis A wide variety of methods have been proposed, including methods. Among these, the liquid backwashing method, the gas backwashing method, and the bubbling method are generally widely used alone or in combination as appropriate. As a chemical cleaning method, a method of dissolving and removing deposits with a chemical solution such as an acid, an aqueous alkali solution, or a cleaning agent is known.
[0004]
[Problems to be solved by the invention]
Generally, when a conventionally known physical cleaning method is used, the cleaning effect is not always satisfactory. For example, when the filtration process and the cleaning process are continuously operated by sequence control or the like, it takes several days to several months. The permeation flux is greatly reduced. Therefore, it is necessary to perform chemical cleaning in order to recover the permeation flux. In general liquid backwashing methods, it is necessary to install a pump for backwashing, and since the permeate obtained by membrane filtration is used for backwashing, the liquid backwashing method is said to be an efficient method. hard. The gas backwashing method requires a large amount of high-pressure gas, so a pressurized gas supply device equipped with a large-capacity air compressor, etc. is required, and noise caused by high-pressure gas being ejected during backwashing is a problem. It may become. On the other hand, when a chemical cleaning method using a chemical solution such as an acid is performed, filtration is temporarily stopped, and then a step of cleaning with the chemical solution and removing the chemical solution after the cleaning is required. In addition, there is a problem that a large amount of cleaning waste liquid must be processed. Therefore, it is necessary to develop an effective physical cleaning method in order to enable continuous filtration operation for a longer period of time.
[0005]
An object of the present invention is to provide a method for cleaning a hollow fiber membrane module, which has an excellent cleaning effect as compared with the conventional method and enables a long-term continuous filtration operation. Another object of the present invention is to provide a filtration device that is effective for performing this cleaning method and can reduce installation space and equipment costs.
[0006]
[Means for Solving the Problems]
The method for cleaning a hollow fiber membrane module of the present invention that solves the above-mentioned problems is a state where the pressure is smaller than the pressure at which gas is released from the stock solution side of the hollow fiber membrane in a state where the stock solution side of the hollow fiber membrane is filled with liquid. Gas is introduced from the filtrate side of the hollow fiber membrane The liquid on the filtrate side of the hollow fiber membrane module is completely discharged within 20 seconds. A pressurization step is performed, and the stock solution side of the hollow fiber membrane is washed with bubbles during or after the pressurization step. Here, the pressure smaller than the pressure at which the gas is released from the stock solution side of the hollow fiber membrane means that when the pressurized process with the gas is performed on the sufficiently wet hollow fiber membrane, the gas is fine in the hollow fiber membrane. This is the pressure of the pressurized gas when bubbles are released from the surface of the opposite hollow fiber membrane through the pores, and the value varies depending on the pore diameter of the hollow fiber membrane and the interfacial tension of the liquid that wets the hollow fiber membrane. . That is, the cleaning method of the present invention introduces a gas having a pressure such that the gas introduced into the hollow fiber membrane is not released from the outer surface of the hollow fiber membrane. This is clearly different from the reverse cleaning method. In the present specification, this pressure is referred to as a bubble point.
[0007]
Although the reason why the method for cleaning the hollow fiber membrane module of the present invention exhibits a significantly superior cleaning effect compared to the conventional cleaning method is not clear, the present inventors have estimated that the present invention The operation will be described below by taking the external pressure filtration system shown in FIGS. 4 and 5 as an example.
[0008]
FIG. 4 is a diagram showing the flow of the permeate when one hollow fiber membrane is viewed from the cross-sectional direction when a conventional cleaning method using the permeate is performed. FIG. 5 shows the permeated liquid when one hollow fiber membrane is viewed from the cross-sectional direction when a pressurized gas is introduced in a state where the liquid is filled on the stock solution side of the hollow fiber membrane in the cleaning method of the present invention. It is a figure which shows the flow of. Here, the case where the permeate is allowed to flow using a pump to the filtrate side (inner surface side) of the one-end free type hollow fiber membrane sealed without fixing one end is shown. 4 and 5, the arrow from the inner side to the outer side of the hollow fiber membrane indicates the permeate flowing out from the wall surface of the hollow fiber membrane to the stock solution side outside the hollow fiber membrane, and the length of this arrow indicates the flow rate of the permeate. Represents the size of. As schematically shown in FIG. 4, the permeate introduced into the hollow fiber membrane by the conventional cleaning method preferentially flows out from the vicinity of the permeate introduction part with a small pressure loss to the stock solution side through the wall surface of the hollow fiber membrane. Therefore, in many cases, the permeate that is sufficient to wash the membrane does not flow at the end of the hollow fiber where the pressure loss is large. Therefore, in order to backwash the entire hollow fiber membrane uniformly and effectively, it is necessary to supply a large amount of permeate to the hollow fiber membrane at a high pressure comparable to the pure water permeability at the time of the new membrane. However, it is difficult to actually perform such an operation. In contrast, in the cleaning method of the present invention shown in FIG. 5, a gas having a pressure lower than the bubble point of the hollow fiber membrane is introduced from the filtrate side of the hollow fiber membrane in a state where the liquid is filled on the hollow fiber membrane. A pressurizing step is performed. As shown in FIGS. 5a to 5d, the permeated liquid inside the hollow fiber membrane passes through the wall surface of the hollow fiber membrane and is discharged to the stock solution side by the pressurized gas. The liquid level decreases sequentially. At this time, since the vicinity of the liquid surface with a small pressure loss is preferentially back-washed, the entire part up to the end of the hollow fiber membrane is uniformly washed as the permeate liquid level inside the hollow fiber membrane decreases. . As described above with reference to the schematic diagrams, the cleaning method of the present invention makes it possible to uniformly clean the entire hollow fiber membrane with a permeate, which is significantly superior to a conventional cleaning method using a permeate. It is thought that the cleaning effect is demonstrated. As a technique for washing the hollow fiber membrane by introducing a pressurized gas from the filtrate side of the hollow fiber membrane, there is the gas back washing method described above (Japanese Patent Laid-Open No. 53-108882, Japanese Patent Publication No. 1-5000732). However, the technology described in these publications introduces a pressurized gas that is equal to or higher than the bubble point of the hollow fiber membrane and allows the gas to pass to the stock solution side of the hollow fiber membrane. In the present invention, the pressurized gas introduced to the filtrate side of the hollow fiber membrane is a pressure below the bubble point, and as described above, the present invention is intended to wash the hollow fiber membrane by passing the gas through the hollow fiber membrane. It is not a technology. In this respect, the cleaning method of the present invention is different from the conventional cleaning method.
[0009]
Further, according to the cleaning method of the present invention, as shown in e of FIG. 5, after all of the permeated liquid inside the hollow fiber membrane is discharged from the hollow fiber membrane and the washing with the permeated liquid is finished, the hollow fiber membrane is The hollow fiber membrane is expanded as shown by the broken line in FIG. At this time, the SS component adhering to the outside of the hollow fiber membrane is peeled off or cracked, and the SS component is likely to fall off in the washing step with bubbles performed during or after the pressurizing step. As described above, in the cleaning method of the present invention, the fine dimensional change occurs in the hollow fiber membrane by the gas pressurization step, and the attached SS component is peeled off or cracked. This is considered to be another reason that the cleaning effect that is remarkably superior to the method is exhibited.
[0010]
The method for cleaning a hollow fiber membrane module of the present invention includes a hollow fiber membrane module having gas inlets on the filtrate side and the stock solution side, a liquid feed pump for supplying the stock solution to the hollow fiber membrane module, and the hollow fiber A pressurized gas supply device for supplying pressurized gas to the membrane module; and a control device for operating the liquid feed pump and the pressurized gas supply device, wherein the control device supplies the stock solution to the hollow fiber membrane module. In the state where the stock solution side of the hollow fiber membrane is filled with the stock solution, the gas having a pressure smaller than the pressure at which the gas is released from the stock solution side of the hollow fiber membrane is passed from the gas inlet on the filtrate side to the hollow fiber membrane. A pressurization step supplied to the module is performed, and during or after the pressurization step, gas is introduced into the hollow fiber membrane module from the gas inlet on the raw liquid side of the hollow fiber membrane, and the hollow fiber membrane is washed with bubbles Bubble cleaning process It can be performed using the configured filtration device to perform. As will be described later, this filtration device can be provided with a pretreatment device such as an oxidative precipitation device for ions according to its application.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The hollow fiber membrane used in the present invention includes polysulfone resin hydrophilized with polyvinyl alcohol resin, polysulfone resin to which hydrophilic polymer is added, polyvinyl alcohol resin, polyacrylonitrile resin, cellulose acetate. It is preferable in that it is made of a hydrophilic material such as a polyethylene resin or a hydrophilized polyethylene resin because it has high hydrophilicity and is excellent in the difficulty of SS component adhesion and exfoliation of the attached SS component. Hollow fiber membranes made of other materials can also be used. For example, polyolefin, polysulfone, polyethersulfone, ethylene-vinyl alcohol copolymer, polyacrylonitrile, cellulose acetate, polyvinylidene fluoride, polyperfluoroethylene, polymethacrylate, polyester, polyamide Hollow fiber membranes composed of organic polymer materials such as ceramics, hollow fiber membranes composed of inorganic materials such as ceramics can be selected according to the use conditions, desired filtration performance, etc. . Here, a polysulfone resin hydrophilized with a polyvinyl alcohol resin, a polysulfone resin to which a hydrophilic polymer is added, or a hollow fiber membrane made of a polyvinyl alcohol resin is not only excellent in the above-described hydrophilicity, Since it is excellent also in heat resistance, it is especially preferable. When an organic polymer material is used, it may be a copolymer obtained by copolymerizing other components in an amount of 30 mol% or less, or a blend of other materials in an amount of 30 wt% or less.
[0012]
When an organic polymer hollow fiber membrane is used, the method for producing the hollow fiber membrane is not particularly limited, and a method appropriately selected from known methods depending on the characteristics of the material and the desired hollow fiber membrane performance Can be adopted. Generally, a melt spinning method, a wet spinning method, a dry / wet spinning method, or the like is employed. From the viewpoint of water permeability, the hollow fiber membrane preferably has an asymmetric structure having a dense layer and a support layer. However, since a hollow fiber membrane generally produced by a melt spinning method has a symmetrical structure, wet spinning is preferable. It is preferable to produce by a phase change method such as a method or a dry-wet spinning method.
[0013]
The pore diameter of the hollow fiber membrane used in the present invention is not particularly limited, but is preferably in the range of 0.001 to 1 micron because it has high water permeability and is less likely to reduce the filtration efficiency. Here, the pore diameter refers to the particle diameter of a reference material from which 90% is excluded when various reference substances with known particle diameters such as colloidal silica, emulsion, and latex are filtered through a hollow fiber membrane. The pore diameter is preferably uniform. With an ultrafiltration membrane, it is impossible to determine the pore size based on the particle size of the reference material as described above. However, when a similar measurement is performed using a protein with a known molecular weight, Those having a molecular weight of 3000 or more are preferred.
[0014]
From the viewpoint of the mechanical properties of the hollow fiber membrane and the membrane area as a module, the outer diameter of the hollow fiber membrane is preferably set in the range of 200 to 3000 microns, more preferably in the range of 500 to 2000 microns. preferable. Similarly, the thickness of the hollow fiber membrane is preferably in the range of 50 to 700 microns, and more preferably in the range of 100 to 600 microns.
[0015]
In the present invention, the hollow fiber membrane is modularized and used for filtration. The form of the module can be appropriately selected according to the filtration method, filtration conditions, washing method, and the like, and a hollow fiber membrane module may be configured by mounting one or a plurality of hollow fiber membrane elements. As the form of the module, for example, a bundle of dozens to hundreds of thousands of hollow fiber membranes is made into a U-shape in the module, one end of the hollow fiber bundle is collectively sealed with an appropriate sealing material, Examples include one in which one end of a hollow fiber bundle is sealed with a suitable sealing material one by one (free state), and one in which both ends of the hollow fiber bundle are opened. Further, the shape of the hollow fiber membrane module is not particularly limited, and may be, for example, a cylindrical shape or a screen shape. In the cleaning method of the present invention, the effect of cleaning the membrane surface by bubbles is extremely high. Therefore, it is particularly preferable to use a “one end free” type module in which one end of each hollow fiber bundle is sealed in a free state.
[0016]
Examples of the filtration method using the hollow fiber membrane module used in the present invention include external pressure total filtration, external pressure circulation filtration, internal pressure total filtration, and internal pressure circulation filtration. The method is appropriately selected according to desired processing conditions and processing performance. be able to. From the viewpoint of membrane life, a circulation system capable of simultaneously cleaning the surface of the filtration coating film is preferable, and from the viewpoint of simplicity of equipment, installation cost, and operation cost, a total filtration system is preferable. In the cleaning method of the present invention, when cleaning the membrane surface with bubbles, a cleaning effect is exhibited by rubbing the hollow fiber membranes together, and therefore an external pressure filtration method is more preferable.
[0017]
In the present invention, in a state where the liquid side of the hollow fiber membrane is filled with liquid, a pressurizing step is performed in which a gas having a pressure less than the bubble point of the hollow fiber membrane is introduced from the filtrate side of the hollow fiber membrane. Examples of the gas used include air and nitrogen. At the time of the pressurizing step and when the membrane surface is washed with bubbles, which will be described later, it is necessary that the stock solution side of the hollow fiber membrane is filled with liquid. The pressure of the gas used in the pressurizing step is selected within a range not exceeding the lowest value among the bubble point of the hollow fiber membrane, the bursting pressure of the hollow fiber membrane, and the durable pressure of the hollow fiber membrane module. Membrane bubble point and burst pressure are both 5.0 kg / cm ² Is greater than 1.0 to 5.0 kg / cm. ² Is preferably within the range of 1.5 to 3.0 kg / cm. ² It is more preferable that it is in the range. The pressure of the pressurized gas is 1.0 kg / cm ² If it is less, the effect of the present invention may not be sufficiently exhibited. At least one of the bubble point of the hollow fiber membrane, the bursting pressure of the hollow fiber membrane and the durability pressure of the hollow fiber membrane module is 5.0 kg / cm ² Is smaller than the upper limit of the pressure of the pressurized gas.
[0018]
The time for performing the pressurization step with gas needs to be longer than the time at which the liquid on the filtrate side of the hollow fiber membrane module can be completely discharged, but the amount of pressurized gas introduced per unit time The time required for the pressurizing step differs depending on the volume of the hollow fiber membrane module on the filtrate side. In the case of the external pressure filtration method, it is necessary to set the pressurization time in consideration of the internal volume of the hollow fiber membrane.
[0019]
In the pressurizing step with gas, backwashing is performed by the filtrate filled in the pipe connecting the pressurized gas injection part and the hollow fiber membrane module and in the hollow fiber membrane module. For example, the amount of liquid at the time of backwashing can be increased by providing a retention part such as a permeate tank in the middle part of the pipe.
[0020]
In the present invention, the raw liquid side of the hollow fiber membrane is washed with bubbles during or after the above-described gas pressurization step. Examples of the gas used in the bubble washing step include air and nitrogen. The supply amount of bubbles is not particularly limited, but since the membrane cleaning effect is high and the risk of membrane breakage is small, the supply amount of bubbles is 1 m in area of the hollow fiber membrane. ² It is preferably within the range of 5 to 500 normal liters / hour, and more preferably within the range of 10 to 300 normal liters / hour. When the above-mentioned “one end free” type module is used, the effect of cleaning the membrane surface by bubbles becomes extremely high.
[0021]
The hollow fiber membrane can be washed with a chemical solution after filtration or after reverse washing to dissolve and remove organic substances, inorganic substances, etc. adhering to the hollow fiber membrane. Here, as a chemical cleaning method, a method of treating with an alkali such as an aqueous sodium hydroxide solution to remove organic substances, inorganic materials, a method of treating with an acid such as an acid aqueous solution to remove metals, and a cleaning agent There are a method of treating with, a method of continuously carrying out a combination of these, and the hollow fiber membrane can be regenerated.
[0022]
A series of steps such as filtration, pressurizing step with gas, cleaning with bubbles, and chemical solution cleaning, which have been described so far, can be automatically performed by performing sequence control with a control device. For example, after filtering for a certain period of time, the pressurization step with gas and the membrane surface cleaning with bubbles are performed once or several times, and then with water once or several times as necessary, followed by chemical cleaning. A series of washing steps are automatically and continuously performed by sequence control, and the operation can be stably continued for a long time while alternately repeating the filtration and the washing steps of the hollow fiber membrane and the filtration line. It is also possible to continue the operation stably for a long period of time with a so-called select switch method in which the filtration process and the washing process are continuously repeated by sequence control, and the chemical solution is manually washed when clogging becomes large. .
[0023]
The cleaning method of the hollow fiber membrane module of the present invention, regardless of the material constituting the hollow fiber membrane and the shape of the module, exhibits an excellent cleaning effect than the conventional cleaning method. It is possible to perform stable filtration continuously for a long time with a higher permeation flux than before. For example, in the food industry, sterilization / turbidity / iron removal / manganese removal of raw water, sterilization / fine particle removal of cleaning water, sterilization / fine particle removal of natural water, sterilization / purification of soy sauce, sterilization of sake・ Purification, vinegar sterilization / purification, mirin purification, seasoning sterilization / purification, product recovery from brewing oil, sugar solution sterilization / fine particle removal / purification, honey purification, enzyme / protein purification, Concentration, purification of fermentation broth, recovery and purification of protein from cheese whey, production of high protein milk by concentration of milk, recovery of protein from fishery processing wastewater, concentration of fish protein, recovery of meat protein from meat processing waste, Separation of red blood cells from pig blood, concentration and purification of albumin and globulin in blood, recovery and purification of physiologically active substances from soybean whey, protein recovery from soybean broth, oil protein toxin removal and protein concentration, potato starch Industrial wastewater Useful protein recovery, recovery and purification of natural pigments, recovery and purification of various enzymes, clarification and sterilization of liquid beverages, concentration of citrus and apple peptin solutions, and purification of fermentation broth by recovery of bacterial cells and metabolites In the medical field, pretreatment of raw water and ultrapure water production equipment, cleaning water pyrogen removal, injection water production, dialysis water production, dialysate purification, vaccines, enzymes and viruses・ Separation, concentration and purification of physiologically active substances such as nucleic acids and proteins, hormone purification, artificial blood production, polysaccharide concentration and purification, hospital hand washing water sterilization, surgical instrument washing water sterilization Yes, in the electronics industry, reverse osmosis membrane pretreatment, ultra pure water final filter, ultra pure water use point filter, ultra pure water unit built-in filter, cleaning water It can be used for applications such as particle removal, polishing wastewater recovery, and dicing wastewater recovery. In the chemical industry, paint concentration / recovery, oil separation / recovery, emulsion separation / recovery, colloid separation / recovery, It can be used for applications such as fine powder cleaning and purification, removal of fine particles of washing water, plating solution purification, and electrodialysis pretreatment. In the water treatment field, it removes MLSS from waterworks, tertiary treatment of wastewater, and collection of wastewater.・ Can be used for reuse, purification of nuclear power generation wastewater, removal of bacteria, etc. In the field of textile and dyeing processing, closed PVA desizing wastewater, recovery and reuse of textile processing oil, and hair washing wastewater It can be used for the recovery of lanolin in sericin and the processing of sericin from silk processing wastewater. In the steel and machining fields, barrel polishing wastewater recovery, buff polishing wastewater recovery, rolling oil drainage treatment Applications such as water treatment, water-soluble cutting oil drainage treatment, animal and vegetable oil processing wastewater treatment, emulsion removal / cleaning agent recovery from degreased washing wastewater, rinse water emulsion removal / rinsing water recovery, ink removal from screen plate cleaning agent, etc. Can be used.
[0024]
Next, an example of the filtration device of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an example of a filtration apparatus using an external pressure type hollow fiber membrane module that can be used for performing the above-described cleaning method. In this filtration device, the hollow fiber membrane module 1 in which the hollow fiber membrane element 4 is housed is partitioned by a partition plate 2 so that the upper part is the filtrate side A and the lower part is the stock solution side B. A number of protective cylinders 3 in which the hollow fiber membrane elements 4 are accommodated are attached to the partition plate 2 in a number corresponding to the hollow fiber membrane elements 4. The filtrate side A is provided with a filtrate outlet 5 and a pressurized gas introduction port 6, and the stock solution side B is provided with a stock solution introduction port 7, a gas discharge port 8, a gas introduction port 9 and a stock solution discharge port 10. . That is, in this filtration device, a pressurized gas inlet 6 is provided on the filtrate side A, and a gas inlet 9 is provided on the stock solution side B, which is a feature of this filtration device.
[0025]
Next, an example of the operation method of the filtration device of the present invention will be described with reference to FIG. From the state in which all the valves are closed, the gas discharge port valve 24, the stock solution inlet port valve 21 and the filtrate outlet valve 23 are opened, the feed pump 29 is operated to introduce the stock solution to the stock solution side D of the filtration container 25, and the gas After the stock solution overflows from the outlet valve 24, the gas outlet valve 24 is closed to start filtration. As the filtration time elapses, the SS component adheres to the membrane surface of the hollow fiber membrane element 26 and the filtration ability is lowered. Subsequently, the hollow fiber membrane is washed by the method of the present invention. That is, after the liquid feed pump 29 is stopped, the stock solution inlet valve 21 and the filtrate outlet valve 23 which are opened in the filtration process are closed to stop the filtration, and then the gas outlet valve 24 and the addition valve are operated while the air compressor 30 is operated. The pressurized gas introduction port valve 22 is opened to introduce a pressurized gas into the filtrate side C of the filtration container 25 to perform a pressurizing process. At this time, the filtrate in the stock solution side C and the hollow fiber membrane is pushed out to the stock solution side D through the wall surface of the hollow fiber membrane, and is discharged to the outside through the gas discharge port valve 24. Further, simultaneously with the start of the pressurization process or after the pressurization process is performed for a predetermined time, the gas inlet valve 28 is opened and cleaning with bubbles is performed for a predetermined time. After the above-described cleaning process is completed, the gas inlet valve 28 is closed, the stock solution outlet valve 27 is opened to drain the drain, and the process returns to the filtration process.
[0026]
FIG. 3 shows the correlation between each step and the opening / closing of the operation valve in the basic operation method of the filtration device illustrated in FIG. Here, in FIG. 3, when the circle is attached, it means that the valve is open. In addition to this basic operation method, other processes such as a process for cleaning the hollow fiber membrane surface and the inside of the hollow fiber membrane module by repeating drain discharge and full water, and a flushing cleaning process are added as necessary. It is also possible to do.
[0027]
The filtration device of the present invention includes (1) a reaction tank, an alkaline component storage tank such as an aqueous sodium hydroxide solution, and an alkaline component injection pump that injects an alkaline component from the alkaline component storage tank into the stock solution in the reaction tank; An apparatus for oxidizing and precipitating ions such as iron and manganese, comprising an oxidant storage tank such as sodium hypochlorite and an oxidant injection pump for injecting an oxidant into the stock solution from the oxidant storage tank; ) A storage tank for acid or alkali components for pH adjustment, an injection pump for injecting acid or alkali components into the stock solution, a flocculant storage tank for sulfated clay, polyaluminum chloride (PAC), and the stock solution A flocculant apparatus comprising a flocculant injection pump for injecting the flocculant from the flocculant storage tank; (3) “1,1,1-trichloroethane alternative cleaning system” Filter element type oil / water separator, coalesced resin element type oil / water separator, pressurized flotation device, as described on pages 52-54 of "Information maintenance contributing to conversion promotion" (November 1994, Industrial Infrastructure Development Fund) Various oil-water separators such as oil skimmers, electric oil-water separators, coalescers, etc., (4) "Second CFC / Triethane Substitute Seminar Materials" (November 12, 1993, Nagase Sangyo Co., Ltd., Electronics Department) Humins, which cannot be removed by conventional membrane filtration alone, in combination with various pretreatment devices according to the application, such as a charge-type agglomeration device and (5) an activated carbon adsorption device. Fine suspensions such as quality can be removed, and oil that causes clogging of the membrane can be removed.
[0028]
FIG. 6 shows a reaction tank, an alkali component storage tank, an alkali component injection pump for injecting an alkali component into the stock solution from the alkali component storage tank, an oxidant storage tank, and an oxidant from the oxidant storage tank to the stock solution. And an oxidizer injection pump having an oxidant injection pump for injecting ions, and the stock solution in which ions are oxidized and precipitated by the oxidative precipitation apparatus is supplied to the hollow fiber membrane module. An example of a filtration apparatus is shown. The basic operation method of this filtration apparatus is as follows. That is, in FIG. 6, the alkali component in the alkali component storage tank 31 is added to a predetermined amount by the alkali component addition pump 32 in the middle of the piping from the stock solution feed pump 36 to the reaction tank 35, and then the oxidant is stored. The oxidant in the tank 33 is added by the oxidant injection pump 34 so as to be a predetermined amount. In this case, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, etc. are mentioned as the alkali component to be added, and the amount added is that the pH of the raw water is 7.8 or higher, preferably 8.0 or higher. Is preferred. Examples of the oxidizing agent include an aqueous sodium hypochlorite solution, an aqueous sodium permanganate solution, and an aqueous hydrogen peroxide solution, but an aqueous sodium hypochlorite solution is preferred because it is easy to handle. The amount of oxidant added is preferably such that when a sodium hypochlorite aqueous solution is used as the oxidant, the residual chlorine concentration in the filtrate that has passed through the hollow fiber membrane module is 0.1 ppm or more, 0.3 ppm The amount which becomes above is more preferable. The stock solution into which the alkali component and the oxidant are injected in this manner undergoes an oxidation / precipitation reaction of ions such as iron and manganese while staying in the reaction tank 35. As the capacity of the reaction tank 35, it is preferable to have a capacity sufficient for the residence time of the stock solution to be 10 to 120 minutes, preferably 20 to 60 minutes. With the filtration device of the present invention equipped with the oxidative precipitation apparatus described so far, from groundwater with a large amount of ions such as iron and manganese that could not be used as drinking water until now, to a level suitable for drinking water Iron, manganese, and the like can be removed, and furthermore, by employing the method for cleaning a hollow fiber membrane module of the present invention, it is possible to operate stably for a long period of time.
[0029]
Next, FIG. 7 shows an acid component (or alkali component) storage tank for pH adjustment, an injection pump for injecting the acid component (or alkali component) into the stock solution, a flocculant storage tank, and the aggregation in the stock solution. The filtration device of the present invention is provided with a flocculating device including a flocculating agent injection pump for injecting the flocculating agent from the agent storage tank, and the stock solution flocculated by the flocculating device is supplied to the hollow fiber membrane module. An example is shown. The basic operation method of this filtration apparatus is as follows. That is, in FIG. 7, the acid component (or alkali component) in the acid or alkali component storage tank 41 is converted by the acid component (or alkali component) addition pump 42 in the middle of the piping from the liquid feed pump 29 to the stock solution inlet valve 21. A predetermined amount is added, and then the flocculant in the flocculant storage tank 43 is added by the flocculant injection pump 44. In this case, examples of the acid component or alkali component to be added include hydrochloric acid aqueous solution, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, sodium carbonate aqueous solution, and the like, and the flocculant includes aluminum sulfate (sulfur sulfate) aqueous solution, polychlorination. Examples thereof include an aluminum (PAC) aqueous solution, a sodium aluminate aqueous solution, a ferric chloride aqueous solution, and a polymer flocculant. If necessary, after adding an acid component (or alkali component) and a flocculant, it is also possible to store in a reaction vessel and to sufficiently advance the agglomeration reaction, and then introduce it into a membrane filtration device. From the groundwater containing a large amount of organic components called humic substances that could not be used as drinking water until now, to the level suitable for drinking water by the filtration device of the present invention provided with the aggregating device described so far. It is easy to remove organic components, and it is also possible to apply to wastewater treatment containing minute suspended components. Conventionally, when a large amount of an aggregating agent such as aluminum sulfate or polyaluminum chloride is added, the hollow fiber membrane is clogged and stable operation for a long period of time has been difficult. Therefore, even when a flocculant is added on the order of several hundred ppm, it becomes possible to operate stably for a long period of time.
[0030]
In FIG. 8, an example of the filtration apparatus of this invention provided with the electrical oil-water separator is shown. The basic operation method of this filtration apparatus is as follows. That is, the stock solution is introduced into the electric oil / water separation composed of the charge filter 52 and the coalescer 53 by the feed pump 51 to remove the oil, and then the stock solution is introduced into the hollow fiber membrane module 26 by the feed pump 29. In this filtering device, the stock solution is circulated by partially opening (or fully opening) the circulation valve 54, and filtration is performed by a circulation filtration method. A part or all of the circulating fluid is again introduced into an electric oil / water separator comprising a charge filter 52 and a coalescer 53, and oil / water separation and membrane filtration are successively performed. Further, it is possible to perform a concentration operation by installing a concentration tank in which the stock solution is stored. By the filtration device of the present invention equipped with the oil-water separation device described so far, oil agent separation / recovery, emulsion separation / recovery, rolling oil drainage treatment, water-soluble cutting oil wastewater treatment, animal and vegetable oil processing wastewater treatment, Membrane filtration technology can be applied to applications such as removal of emulsion from degreasing and cleaning wastewater, recovery of washing agent, removal of rinse water and removal of rinse water, and the method for cleaning the hollow fiber membrane module of the present invention should be adopted. This makes it possible to continue operation stably for a long period of time.
[0031]
FIG. 9 shows an example of the filtration device of the present invention that is provided with a charge type agglomeration device and configured so that the stock solution that has passed through the charge type agglomeration device is supplied to the hollow fiber membrane module. The basic operation method of this filtration apparatus is as follows. That is, the stock solution is introduced into the charge aggregating device 61 by the liquid feeding pump 29, and after the SS component is agglomerated by the charge agglomeration effect, it is introduced into the hollow fiber membrane module 26. An electrode 62 connected to a direct current (or alternating current) power source 63 is installed inside the charge aggregating device 61, and electrical neutralization is performed when the stock solution passes through the electric field formed by the electrode 62. Aggregation and enlargement of the SS component occur due to the action, so that the separation performance in the membrane filtration device is improved and the progress of clogging can be reduced.
[0032]
FIG. 10 shows an example of a filtration device according to the present invention that is equipped with a chemical liquid tank for chemical cleaning of a hollow fiber membrane and a chemical solution feeding pump, and is configured so that the chemical solution is supplied to the raw solution side of the hollow fiber membrane module. Indicates. The basic operation method of this filtration apparatus is as follows. That is, the chemical solution pump 73 is operated with the stock solution inlet valve 21, the gas outlet valve 24, and the chemical solution introduction valve 73 opened, and the chemical solution such as acid and alkali stored in the chemical solution cleaning chemical tank 71 is hollow. Introduce into the yarn membrane module and carry out chemical cleaning of the hollow fiber membrane module. If necessary, it is also possible to open the stock solution discharge valve 27 and the chemical solution discharge valve 75 to circulate the chemical solution and perform circulating chemical solution cleaning. By using the filtration device of the present invention equipped with the chemical solution cleaning device described so far, it becomes possible to perform the chemical solution cleaning of the hollow fiber membrane without removing the hollow fiber membrane module.
[0033]
FIG. 11 shows an example of the filtration device of the present invention that includes an electrolyzed water production apparatus and an electrolyzed water feed pump, and is configured to wash the hollow fiber membrane by introducing electrolyzed water into the hollow fiber membrane module. Indicates. The basic operation method of this filtration apparatus is as follows. That is, an electrolyte such as sodium chloride stored in the electrolyte storage tank 83 is injected into the water stored in the electrolytic water storage tank 81 by the electrolyte injection pump 84 and guided to the electrolytic tank 86 by the liquid feed pump 85 to produce electrolytic water. Do. Examples of the electrolytic cell 86 include those in which the anode chamber and the cathode chamber are separated by a diaphragm such as a porous membrane and an ion exchange membrane, and those having no diaphragm. The electrolyzed water stored in the electrolyzed water storage tank 81 is operated by operating the electrolyzed water feed pump 82 in a state where the stock solution inlet valve 21, the gas outlet valve 24 and the electrolyzed water inlet valve 87 are opened. It introduce | transduces in a hollow fiber membrane module, and a hollow fiber membrane module is wash | cleaned. If necessary, it is possible to open the stock solution discharge valve 27 and the chemical solution discharge valve 89 to circulate the chemical solution and to perform the circulating chemical solution cleaning. It is also possible to connect the introduction port of the electrolyzed water to the filtrate side of the hollow fiber membrane module and perform the back washing with the electrolyzed water of the hollow fiber membrane. The hollow fiber membrane module can be used to wash the hollow fiber membrane with the electrolytic water in addition to the conventional chemical solution washing by using the electrolyzed water production apparatus and the filtration apparatus of the present invention equipped with the electrolyzed water feed pump as described above. It is also possible to carry out without removing.
[0034]
The filtration device of the present invention can be further purified and purified by combining the post-treatment device according to the application such as ion exchange resin, ion exchange membrane, reverse osmosis membrane, activated carbon adsorption device, activated sludge treatment device, etc. Is possible.
[0035]
In addition, it is possible to reduce the amount of waste by treating the concentrated liquid or drain discharged from the filtration device of the present invention with a flocculating device, an incinerator, or the like including a precipitation tank, a flocculant adding device and a reaction tank.
[0036]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. From the results of the following examples and comparative examples, it is apparent that stable filtration over a long period of time is possible according to the present invention.
[0037]
Example 1
It is made of polysulfone resin surface-hydrophilized with polyvinyl alcohol, has an average pore size of 0.1 microns, and a bubble point of 5.0 kg / cm. ² Membrane area made of hollow fiber membrane is 7.0m ² Using a “one-end free” type hollow fiber membrane module, constant flow rate filtration was performed under conditions of an external pressure total filtration method and a flow rate of 560 liters / hour using 10 to 20 ° C. river surface water as raw water. A sodium hypochlorite aqueous solution was continuously added to the raw water so that the free chlorine concentration in the filtrate was 1 ppm. The hollow fiber membrane is washed once every 30 minutes by sequence control, and the pressure is 2.0 kg / cm on the filtrate side of the hollow fiber membrane module. ² The air was pressurized for 20 seconds by introducing air, and then from the lower part of the hollow fiber membrane module on the stock solution side, the pressure was 1.0 kg / cm. ² Was blown out for 1 minute at a flow rate of 600 normal liters / hour. During the filtration operation, the transmembrane pressure difference is measured periodically, and the differential pressure is 1.5 kg / cm. ² The filtration life was 65 days, when the filtration time to reach the filtration life of the hollow fiber membrane module was taken as 65 days.
[0038]
Example 2
Instead of a hollow fiber membrane made of a polysulfone resin surface-hydrophilized with polyvinyl alcohol, it is made of a polyvinyl alcohol resin and has an average pore diameter of 0.1 microns and a bubble point of 5.0 kg / cm. ² The river surface water was filtered in the same manner except that the above hollow fiber membrane was used. The filtration life evaluated by the transmembrane pressure was 63 days.
[0039]
Example 3
Instead of a hollow fiber membrane made of a polysulfone resin surface-hydrophilized with polyvinyl alcohol, it is made of a polyethylene resin hydrophilized, has an average pore diameter of 0.1 microns, and a bubble point of 3.0 kg / cm. ² Membrane area made of hollow fiber membrane is 8.0m ² The river surface water was filtered in the same manner except that a “both ends fixed (both ends of the hollow fiber membrane)” type hollow fiber membrane module was used. The filtration life as evaluated by transmembrane pressure was 52 days.
[0040]
Example 4
It is made of polyacrylonitrile resin, has a molecular weight cut-off of 3000, and a bubble point of 5.0 kg / cm. ² The membrane area of the hollow fiber membrane is 5.0m ² Using a "both ends fixed" type hollow fiber membrane module, the raw water is allowed to flow through the hollow fiber membrane at a linear speed of 1 m / sec, while maintaining a constant flow rate under conditions of an internal pressure circulation filtration system and a flow rate of 300 liters / hour. Filtration was performed. The hollow fiber membrane is washed once every 30 minutes by sequence control, and the pressure is 2.0 kg / cm on the filtrate side of the hollow fiber membrane module. ² The air was pressurized for 20 seconds by introducing air, and then the pressure was 1.0 kg / cm from one end of the hollow fiber membrane. ² Were blown out for 1 minute at a flow rate of 500 normal liters / hour. During the filtration operation, the transmembrane pressure difference is measured periodically, and the differential pressure is 1.5 kg / cm. ² The filtration life was 55 days, where the filtration time to reach the filtration life of the hollow fiber membrane module was 55 days.
[0041]
Example 5
It is made of polyacrylonitrile resin, has a molecular weight cut-off of 5000, and a bubble point of 5.0 kg / cm. ² The membrane area of the hollow fiber membrane is 5.0m ² Using a "both ends fixed" type of hollow fiber membrane module, while supplying raw water to the outside of the hollow fiber membrane at a linear speed of 0.5 m / sec, under conditions of an external pressure circulation filtration system and a flow rate of 300 liters / hour Constant flow filtration was performed. The hollow fiber membrane is washed once every 30 minutes by sequence control, and the pressure is 2.0 kg / cm on the filtrate side of the hollow fiber membrane module. ² The air was pressurized for 20 seconds by introducing air, and then the pressure was 1.0 kg / cm from one end of the hollow fiber membrane. ² Were blown out for 1 minute at a flow rate of 500 normal liters / hour. During the filtration operation, the transmembrane pressure difference is measured periodically, and the differential pressure is 1.5 kg / cm. ² The filtration life was 49 days, when the filtration time to reach the filtration life of the hollow fiber membrane module was taken as 49 days.
[0042]
Example 6
After adding sodium hydroxide aqueous solution to well water containing 2.1 ppm iron and 0.2 ppm manganese at pH 7.1 to pH 8.2, the sodium hypochlorite aqueous solution has a residual chlorine concentration of 1 ppm. In this way, the iron and manganese were subjected to an oxidation precipitation treatment by being added for a further 30 minutes. It is made of polysulfone resin surface-hydrophilized with polyvinyl alcohol, has an average pore size of 0.1 microns, and a bubble point of 5.0 kg / cm. ² Membrane area made of hollow fiber membrane is 7.0m ² 49m total membrane area containing 7 “one end free” type hollow fiber membrane elements ² The constant flow rate filtration was performed under the conditions of the external pressure total filtration method and the flow rate of 3500 liters / hour. The hollow fiber membrane is washed once every 30 minutes by sequence control, and the pressure on the filtrate side of the hollow fiber membrane module is 3.0 kg / cm. ² The air was pressurized for 20 seconds by introducing air, and then the pressure was 1.0 kg / cm from the lower part of the hollow fiber membrane module on the stock solution side. ² Were blown out for 1 minute at a flow rate of 4200 normal liters / hour. During the filtration operation, the transmembrane pressure difference is measured periodically, and the differential pressure is 1.5 kg / cm. ² The filtration life was 77 days, when the filtration time to reach the filtration life of the hollow fiber membrane module was taken as 77 days.
[0043]
Example 7
Commercially available liquid sulfuric acid compatible with JISK 1450-1997, a kind of flocculant, in groundwater with a chromaticity of 200 and potassium permanganate consumption of 45 mg / liter taken in the Kanto region, which is said to contain a large amount of humic substances. Water was filtered in the same manner as in Example 1 except that 300 ppm of clay was added and the mixture stirred and retained for 30 minutes was used. The filtration life as assessed by transmembrane pressure was 58 days. The obtained filtrate had a chromaticity of 0 and a potassium permanganate consumption of 6.5 mg / liter, and it complied with the water quality standards defined by Ministry of Health, Labor and Welfare Ordinance No. 69, including other items.
[0044]
Example 8
It consists of a polysulfone resin whose surface is hydrophilized with polyvinyl alcohol, using raw water as the dicing drainage of a silicon wafer for manufacturing IC chips whose SS concentration measured by the method defined in JIS K 0102 14.1 is 30 mg / L, The average pore size is 0.1 micron and the bubble point is 5.0 kg / cm ² Membrane area made of hollow fiber membrane is 7.0m ² 49m total membrane area containing 7 “one end free” type hollow fiber membrane elements ² The constant flow rate filtration was performed under the conditions of an external pressure total filtration method and a flow rate of 1500 liters / hour. The hollow fiber membrane is washed once every 3 hours by sequence control, and the pressure on the filtrate side of the hollow fiber membrane module is 1.8 kg / cm. ² The air was pressurized for 20 seconds by introducing air, and then the pressure was 1.0 kg / cm from the lower part of the hollow fiber membrane module on the stock solution side. ² Were blown out for 1 minute at a flow rate of 4200 normal liters / hour. During the filtration operation, the transmembrane pressure difference is measured periodically, and the differential pressure is 1.5 kg / cm. ² The filtration life was 98 days when the filtration time to reach the filtration life of the hollow fiber membrane module was 98 days.
[0045]
Example 9
Consists of a polysulfone resin whose surface is hydrophilized with polyvinyl alcohol using the barrel polishing waste water of a condenser part having an SS concentration of 1000 mg / L measured by the method defined in JIS K 0102 14.1 as raw water, and having an average pore size of 0 .1 micron with a bubble point of 5.0 kg / cm ² Membrane area made of hollow fiber membrane is 7.0m ² A total membrane area of 21m that contains three "one end free" type hollow fiber membrane elements ² The constant flow rate filtration was performed under the conditions of an external pressure total filtration method and a flow rate of 1500 liters / hour. The hollow fiber membrane is washed once every 30 minutes by sequence control, and the pressure on the filtrate side of the hollow fiber membrane module is 1.9 kg / cm. ² The air was pressurized for 20 seconds by introducing air, and then the pressure was 1.0 kg / cm from the lower part of the hollow fiber membrane module on the stock solution side. ² Was blown out for 1 minute at a flow rate of 1800 normal liters / hour. During the filtration operation, the transmembrane pressure difference is measured periodically, and the differential pressure is 1.5 kg / cm. ² The filtration life was 53 days, where the filtration time to reach the filtration life of the hollow fiber membrane module was 53 days.
[0046]
Comparative Example 1
In Example 1, river surface water was filtered in the same manner except that the operation with pressure from the filtrate side was not performed and the operation was stopped for 20 seconds. The filtration life as assessed by transmembrane pressure was 19 days.
[0047]
Comparative Example 2
In Example 1, instead of the pressurizing operation with the gas from the filtrate side, the river table was similarly used except that the filtrate was supplied from the filtrate side with a pump at a flow rate of 1120 liters / hour for 5 seconds and backwashed. The running water was filtered. The filtration life as evaluated by the transmembrane pressure was 23 days.
[0048]
Comparative Example 4
In Example 1, the surface water of the river was filtered in the same manner except that the operation was stopped for 1 minute without performing the cleaning with the bubbles for ejecting air from the lower part of the hollow fiber membrane module on the stock solution side. The filtration life evaluated by transmembrane pressure difference was 20 days.
[0049]
【The invention's effect】
By the method for cleaning a hollow fiber membrane module of the present invention, a continuous filtration operation can be performed stably for a long period of time, and the frequency of chemical cleaning can be reduced. It is effective to use the filtration device of the present invention for the above-described method for cleaning the hollow fiber membrane module of the present invention.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of an external pressure type hollow fiber membrane module used in the filtration device of the present invention.
FIG. 2 is a view showing an example of a filtration device of the present invention using an external pressure type hollow fiber membrane module.
3 is a diagram showing a basic operation program of the filtration device of the present invention shown in FIG.
FIG. 4 is a diagram schematically showing the flow of a permeate during conventional permeate backwashing.
FIG. 5 is a diagram schematically showing the flow of permeate during the pressurizing step with the gas of the present invention.
FIG. 6 is a diagram showing an example of the filtration device of the present invention provided with an oxidative precipitation apparatus for ions.
FIG. 7 is a view showing an example of a filtration device of the present invention provided with an agglomeration reaction device.
FIG. 8 is a view showing an example of a filtration device of the present invention provided with an electric oil / water separator.
FIG. 9 is a view showing an example of a filtration device of the present invention provided with a charge type aggregating device.
FIG. 10 is a view showing an example of a filtration device of the present invention including a chemical liquid tank for chemical cleaning of a hollow fiber membrane and a chemical liquid feeding pump.
FIG. 11 is a diagram showing an example of the filtration device of the present invention including an electrolyzed water production device and an electrolyzed water feed pump.
[Explanation of symbols]
A: Filtrate side
B: Stock solution side
1: Hollow fiber membrane module
2: Partition plate
3: Protective cylinder
4: Hollow fiber membrane element
5: Filtrate outlet
6: Pressurized gas inlet
7: Stock solution inlet
8: Gas outlet
9: Gas inlet
10: Stock solution outlet
C: Filtrate side
D: Stock solution side
21: Stock solution inlet valve
22: Pressurized gas inlet valve
23: Filtrate outlet valve
24: Gas outlet valve
25: Filtration container
26: Hollow fiber membrane module
27: Stock solution outlet valve
28: Gas inlet valve
29: Liquid feed pump
30: Air compressor
31: Alkali component storage tank
32: Alkaline component injection pump
33: Oxidant storage tank
34: Oxidant injection pump
35: Reaction tank
36: Raw water feed pump
41: Acid component (or alkali component) storage tank
42: Acid component (or alkali component) injection pump
43: Flocculant storage tank
44: Flocculant injection pump
51: Liquid feed pump
52: Charge filter
53: Coalescer
54: Circulation valve
61: Charge-type aggregator
62: Electrode
63: Power supply
71: Chemical tank for cleaning chemicals
72: Chemical feed pump
73: Chemical solution introduction valve
74: Backflow prevention valve
75: Chemical solution discharge valve
81: Electrolyzed water storage tank
82: Electrolyzed water pump
83: Electrolyte storage tank
84: Electrolyte injection pump
85: Liquid feed pump
86: Electrolysis tank
87: Electrolyzed water introduction valve
88: Backflow prevention valve
89: Electrolyzed water discharge valve

Claims

In a state in which the liquid side of the hollow fiber membrane is filled with liquid, a gas having a pressure smaller than the pressure at which the gas is released from the raw liquid side of the hollow fiber membrane is introduced from the filtrate side of the hollow fiber membrane, and the hollow fiber is within 20 seconds. A hollow fiber membrane module characterized by performing a pressurization step for completely discharging the liquid on the filtrate side of the membrane module, and washing the stock side of the hollow fiber membrane with bubbles during or after the pressurization step Cleaning method.
2. The method for washing a hollow fiber membrane module according to claim 1, wherein the stock solution is supplied from the outer surface side of the hollow fiber membrane, and the filtrate is taken out from the inner surface side of the hollow fiber membrane.
The method for cleaning a hollow fiber membrane module according to claim 1 or 2, wherein the pressure of the gas introduced during the pressurizing step is in the range of 1.0 to 5.0 kg / cm2.
A hollow fiber membrane module having gas inlets on the filtrate side and the stock solution side, a liquid feed pump for supplying the stock solution to the hollow fiber membrane module, and a pressurized gas supply for supplying pressurized gas to the hollow fiber membrane module And a control device for operating the liquid feed pump and the pressurized gas supply device, and after the supply of the stock solution to the hollow fiber membrane module is stopped by the control device, the stock solution side of the hollow fiber membrane is the stock solution. The gas having a pressure smaller than the pressure at which the gas is released from the raw solution side of the hollow fiber membrane is supplied to the hollow fiber membrane module from the gas inlet on the filtrate side, and the hollow fiber membrane is within 20 seconds. Perform a pressurization process to completely discharge the liquid on the filtrate side of the module, and after the pressurization process or after the pressurization process, gas is introduced into the hollow fiber membrane module from the gas inlet on the raw liquid side of the hollow fiber membrane and hollow The thread membrane is washed with air bubbles Filtration apparatus characterized by being configured to perform a bubble washing process that.
The filtration apparatus according to claim 4, wherein the hollow fiber membrane module has a filtrate outlet and a gas inlet on the filtrate side, and has a raw liquid inlet, a gas outlet, a gas inlet and a raw liquid outlet on the raw liquid side.
The pressurization step and the bubble cleaning step are configured to be performed by a valve provided in the hollow fiber membrane module being operated by a control device, and the pressurization step opens the gas outlet on the stock solution side. 6. The filtration apparatus according to claim 5, wherein the bubble side is opened by opening a gas inlet on the filtrate side, and the bubble washing step is performed by introducing gas from the gas inlet on the raw liquid side.
The filtration apparatus according to claim 4, which is an external pressure filtration system in which the stock solution is supplied from the outer surface side of the hollow fiber membrane and the filtrate is taken out from the inner surface side of the hollow fiber membrane.
The filtration device according to claim 4, wherein the hollow fiber membrane module is configured by mounting one or a plurality of hollow fiber membrane elements.
9. The filtration apparatus according to claim 8, wherein the hollow fiber membrane element is a one-end free type hollow fiber membrane element sealed with one end of each hollow fiber membrane not being fixed one by one.
The filtration device according to claim 4, wherein the hollow fiber membrane is made of a hydrophilic polymer.
The filtration device according to claim 10, wherein the hollow fiber membrane is made of a polysulfone resin hydrophilized with a polyvinyl alcohol resin, a polysulfone resin added with a hydrophilic polymer, or a polyvinyl alcohol resin.
A reaction tank, an alkali component storage tank, an alkali component injection pump for injecting an alkali component from the alkali component storage tank into the stock solution in the reaction tank, an oxidant storage tank, and an oxidant storage tank that oxidizes the stock solution from the oxidant storage tank An oxidizer deposition apparatus including an oxidizer injection pump for injecting an oxidant, and configured so that a stock solution in which ions are oxidized and precipitated by the oxidizer is supplied to the hollow fiber membrane module. Item 5. The filtration device according to Item 4.
Acid or alkali component storage tank for pH adjustment, injection pump for injecting acid component or alkali component into stock solution, flocculant storage tank, and flocculant for injecting flocculant into the stock solution from the flocculant storage tank The filtration device according to claim 4, further comprising a flocculation device including an injection pump, wherein the stock solution flocculated by the flocculation device is supplied to the hollow fiber membrane module.
The filtration apparatus according to claim 4, comprising an oil / water separator, and configured so that the stock solution that has passed through the oil / water separator is supplied to the hollow fiber membrane module.
15. The filtration device according to claim 14, wherein the oil / water separator is an oil skimmer, a pressurized flotation device, a coalescer, or an electric oil / water separator.
The filtration device according to claim 14, wherein the filtration device is a circulation filtration method, and the stock solution is circulated between the oil-water separator and the hollow fiber membrane module.
It has a concentration tank in which the stock solution is stored, and after the oil content in the stock solution stored in the concentration tank is removed by the oil / water separator, the stock solution after oil removal is supplied to the hollow fiber membrane module and passes through the hollow fiber membrane module. The filtration device according to claim 16, wherein the circulated liquid is returned to the concentration tank.
The filtration device according to claim 4, comprising a charge type agglomeration device, and configured so that the stock solution that has passed through the charge type agglomeration device is supplied to the hollow fiber membrane module.
A chemical liquid tank for chemical liquid cleaning of the hollow fiber membrane and a chemical liquid feed pump for feeding the chemical liquid stored in the chemical liquid tank are configured so that the chemical liquid is supplied to the raw liquid side of the hollow fiber membrane module. The filtration device according to claim 4.
A hollow fiber membrane comprising an electrolyzed water production device and an electrolyzed water feed pump for feeding electrolyzed water stored in an electrolyzed water storage tank of the electrolyzed water production device, wherein the electrolyzed water is introduced into the hollow fiber membrane module The filtration device according to claim 4, wherein the filtration device is configured to wash the water.