JP2019122929A - Filtration device and method for cleaning hollow fiber membrane - Google Patents

Abstract

To provide a filtration device capable of easily recovering filtration capacity even in a low temperature environment.SOLUTION: A filtration apparatus according to an aspect of the present invention includes a water tank for storing a liquid to be treated, a membrane module having a plurality of hollow fiber membranes aligned vertically and disposed in the water tank, and a heater disposed below the membrane module in the water tank.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a filtration device and a method for cleaning a hollow fiber membrane.

  Various filtration devices for separating impurities in a liquid by filtration membranes are widely used. In such a filtration apparatus, since the impurities adhere to the filtration membrane and the filtration ability is lowered, an operation of recovering the filtration ability is sometimes performed by removing the impurities adhering to the filtration membrane by the cleaning liquid.

  As a method of cleaning the filtration membrane, reverse pressure cleaning is known in which the cleaning solution is supplied in the reverse direction to that in the normal filtration operation. Further, as a method of improving the effect of such reverse pressure washing, it has been proposed to supply a heated washing solution to a filtration membrane (see JP-A-10-192850).

JP 10-192850 A

  As described in the above-mentioned publication, even when the reverse pressure washing is performed with the heated washing solution, the impurities attached to the filtration membrane may not be sufficiently removed. In this case, a method is employed in which the filtration capacity of the filtration membrane is recovered over time by holding the filtration membrane in the state of being immersed in the cleaning liquid. However, when the ambient temperature of the filtration device is low, for example, in winter, the temperature of the washing solution may be lowered, and the effect of washing the filtration membrane may be lowered.

  The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to provide a filtration device and a method of cleaning a hollow fiber membrane which can easily recover the filtration capacity even in a low temperature environment.

  A filtration apparatus according to an aspect of the present invention made to solve the above problems has a water tank for storing a liquid to be treated, and a plurality of hollow fiber membranes which can be aligned vertically. A membrane module, and a heater disposed below the membrane module in the water tank.

  A method for cleaning a hollow fiber membrane according to another aspect of the present invention includes a water tank for storing a liquid to be treated, and a plurality of hollow fiber membranes which can be aligned vertically, and the membrane module disposed in the water tank And cleaning the membrane module of the filtration apparatus with a heater disposed below the membrane module in the water tank and a diffuser provided below the membrane module in the water tank with a cleaning liquid, And a cleaning solution supplying step of supplying a cleaning solution into the water tank, and generating a bubble from the aeration tube to convection the cleaning solution while heating the cleaning solution with the heater to maintain the cleaning solution at a constant temperature. And a heating step.

  The filtration device according to one aspect of the present invention can easily restore its filtration capacity even in a low temperature environment.

FIG. 1 is a schematic longitudinal sectional view of a filtration device according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the filtration device of FIG.

Description of the embodiment of the present invention
A filtration apparatus according to an aspect of the present invention includes a water tank for storing a liquid to be treated, and a plurality of hollow fiber membranes aligned vertically, and a membrane module disposed in the water tank, and in the water tank. And a heater disposed below the membrane module.

  The said filtration apparatus can heat the washing | cleaning liquid stored in a water tank by providing the heater arrange | positioned under the said membrane module in the said water tank. As a result, even in a low temperature environment, the plurality of hollow fiber membranes can be immersed in the heated cleaning liquid to be efficiently washed to recover the filtering ability.

  In the filtration device, the heater may have a sealing portion sealing an opening formed in a lower portion of the side wall of the water tank and a heat generating portion extending from the sealing portion. Thus, by having the sealing portion sealing the opening formed in the lower portion of the side wall of the water tank and the heat generating portion extending from the sealing portion, the opening can be obtained without removing the membrane module from the water tank It is possible to easily carry out the maintenance of the heater by pulling out the above heater.

  In the filtration device, the water tank may have a sloped bottom wall. As described above, when the water tank has the inclined bottom wall, it is possible to easily discharge the concentrate obtained by concentrating the liquid to be treated by filtration.

  In the filtration device, the membrane module may be suspended and held in the water tank. Thus, by suspending the membrane module and holding it in the water tank, the membrane module can be prevented from interfering with the heater, and the membrane is inclined even when the water tank is inclined. The module can be installed horizontally.

  The filtration device may further include an air diffusion pipe disposed below the membrane module in the water tank. Thus, the hollow fiber membrane is oscillated by air bubbles by further providing the aeration pipe disposed below the membrane module in the water tank to promote the cleaning and the cleaning liquid heated by the heater. Convection can be promoted to efficiently heat the cleaning solution.

  The air diffusion tube may extend horizontally through an opening formed in a lower side wall of the water tank. As described above, since the aeration tube extends horizontally through the opening formed in the lower portion of the side wall of the water tank, the aeration tube can be removed from the water tank while the membrane module is disposed. Maintenance of trachea can be easily performed.

  A method for cleaning a hollow fiber membrane according to another aspect of the present invention includes a water tank for storing a liquid to be treated, and a plurality of hollow fiber membranes which can be aligned vertically, and the membrane module disposed in the water tank And cleaning the membrane module of the filtration apparatus with a heater disposed below the membrane module in the water tank and a diffuser provided below the membrane module in the water tank with a cleaning liquid, And a cleaning solution supplying step of supplying a cleaning solution into the water tank, and generating a bubble from the aeration tube to convection the cleaning solution while heating the cleaning solution with the heater to maintain the cleaning solution at a constant temperature. And a heating step.

  The hollow fiber membrane cleaning method includes the cleaning liquid heating step of heating the cleaning liquid with the heater, so that the hollow fiber membrane of the membrane module is immersed in the heated cleaning liquid and efficiently cleaned even under a low temperature environment. As a result, the filtration capacity of the membrane module can be easily restored.

Details of the Embodiment of the Present Invention
Hereinafter, each embodiment of the filtration device according to the present invention will be described in detail with reference to the drawings.

  1 and 2 show the configuration of a filtration device according to an embodiment of the present invention. The filtration apparatus includes a water tank 1 for storing the liquid to be treated, a plurality of membrane modules 2 disposed in the water tank 1, a heater 3 disposed below the membrane module 2 in the water tank 1, and And an air diffuser 4 disposed below the membrane module 2.

<Water tank>
The water tank 1 has a square cylindrical side wall 5 and an inclined bottom wall 6. Further, in the water tank 1, the heater opening 7 to which the heater 3 is attached and the diffusion tube opening 8 to which the air diffuser 4 is attached are formed at the lower part of the side wall 5 on the side where the bottom wall 6 is the highest. A discharge nozzle 9 for discharging the liquid to be treated is disposed at the lower part of the side wall 5 on the lower side.

  A heater nozzle 11 having a heater flange 10 is provided in the heater opening 7. By thus providing the heater nozzle 11 having the heater flange 10 in the heater opening 7, the heater 3 can be easily attached and detached. Similarly, the air diffusion nozzle 8 is provided with an air diffusion nozzle 13 having an air diffusion flange 12.

  The water tank 1 can easily discharge the concentrated liquid to be treated from the discharge nozzle 9 because the bottom wall 6 is inclined. The lower limit of the inclination angle to the horizontal of the bottom wall 6 is preferably 5 °, more preferably 10 °. On the other hand, the upper limit of the inclination angle with respect to the horizontal of the bottom wall 6 is preferably 30 °, and more preferably 20 °. When the inclination angle with respect to the horizontal of the bottom wall 6 is less than the said minimum, there exists a possibility that discharge | emission of a to-be-processed liquid can not fully be promoted. On the other hand, when the inclination angle with respect to the horizontal of the bottom wall 6 exceeds the said upper limit, there exists a possibility that the maintenance etc. of the membrane module 2 may become complicated because the height of the water tank 1 becomes large unnecessarily.

<Membrane module>
The membrane module 2 is vertically aligned to form a plurality of hollow fiber membranes 14 that form a plurality of quadrangular prismatic bundles arranged in a matrix, and a plurality of upper holdings that fix upper ends of the bundles of hollow fiber membranes 14 A member 15, a plurality of lower holding members 16 for fixing the lower end of the bundle of hollow fiber membranes 14, and a connecting member 17 for connecting the upper holding member 15 and the lower holding member 16 are provided. The plurality of membrane modules 2 are connected to a liquid collection pipe 18 for collecting the filtrate filtered by the hollow fiber membranes 14 of the respective membrane modules 2. Also, the plurality of membrane modules 2 and the liquid collection tubes 18 are held by the frame 19.

(Hollow fiber membrane)
The hollow fiber membrane 14 is formed by forming a porous membrane into a tubular shape that allows the solvent in the liquid to be treated to permeate while blocking the permeation of impurities contained in the liquid to be treated to a certain particle size or more. What has resin as a main component can be used. Here, "main component" means a component with the highest content.

  Examples of the thermoplastic resin include polyethylene, polypropylene, polyvinylidene fluoride, ethylene-vinyl alcohol copolymer, polyamide, polyimide, polyetherimide, polystyrene, polysulfone, polyvinyl alcohol, polyphenylene ether, polyphenylene sulfide, cellulose acetate, polyacrylonitrile And polytetrafluoroethylene (PTFE). Among these, PTFE which is excellent in mechanical strength, chemical resistance, heat resistance, weather resistance, nonflammability and the like and is porous is preferable, and uniaxially or biaxially stretched PTFE is more preferable. In addition, other polymers, additives such as a lubricant, and the like may be appropriately blended in the forming material of the hollow fiber membrane 14.

  The lower limit of the ratio of the average pitch in the short side direction to the average outer diameter of the hollow fiber membrane 14 is preferably 1. On the other hand, the upper limit of the ratio of the average pitch in the short side direction to the average outer diameter of the hollow fiber membrane 14 is preferably 3/2, more preferably 7/5. When the ratio of the average pitch in the short side direction to the average outer diameter of the hollow fiber membrane 14 does not reach the above lower limit, the hollow fiber membrane 14 is disposed in a radially crushed state, so that Manufacturing may be difficult. On the other hand, when the ratio of the average pitch in the short side direction to the average outer diameter of the hollow fiber membrane 14 exceeds the above-mentioned upper limit, the density of the hollow fiber membrane 14 in the short side direction may be reduced and sufficient filtration efficiency may not be obtained. There is.

  The lower limit of the average outer diameter of the hollow fiber membrane 14 is preferably 1 mm, more preferably 1.5 mm, and still more preferably 2 mm. On the other hand, the upper limit of the average outer diameter of the hollow fiber membrane 14 is preferably 6 mm, more preferably 5 mm, and still more preferably 4 mm. If the average outer diameter of the hollow fiber membrane 14 does not reach the above lower limit, the mechanical strength of the hollow fiber membrane 14 may be insufficient. On the other hand, when the average outer diameter of the hollow fiber membrane 14 exceeds the above upper limit, the flexibility of the hollow fiber membrane 14 is insufficient, and the vibration and oscillation of the hollow fiber membrane 14 due to the contact of air bubbles become insufficient. There is a possibility that the air gap can not be guided to the central portion of the bundle of hollow fiber membranes 14 by expanding the gap between 14 and the ratio of the surface area to the cross sectional area of the hollow fiber membranes 14 becomes small to reduce the filtration efficiency. .

  The lower limit of the average inner diameter of the hollow fiber membrane 14 is preferably 0.3 mm, more preferably 0.5 mm, and still more preferably 0.9 mm. On the other hand, the upper limit of the average inner diameter of the hollow fiber membrane 14 is preferably 4 mm, more preferably 3 mm. When the average inner diameter of the hollow fiber membrane 14 does not reach the above lower limit, the pressure loss when discharging the treated liquid in the hollow fiber membrane 14 may be large. On the other hand, when the average inner diameter of the hollow fiber membrane 14 exceeds the above-mentioned upper limit, the thickness of the hollow fiber membrane 14 may be reduced, and the mechanical strength and the permeation blocking effect of impurities may be insufficient.

  The lower limit of the ratio of the average inner diameter to the average outer diameter of the hollow fiber membrane 14 is preferably 3/10, more preferably 2/5. On the other hand, the upper limit of the ratio of the average inner diameter to the average outer diameter of the hollow fiber membrane 14 is preferably 4/5, more preferably 3/5. When the ratio of the average inner diameter to the average outer diameter of the hollow fiber membrane 14 does not reach the above lower limit, the thickness of the hollow fiber membrane 14 may be larger than necessary, and the liquid permeability of the hollow fiber membrane 14 may be reduced. On the other hand, when the ratio of the average inner diameter to the average outer diameter of the hollow fiber membrane 14 exceeds the above upper limit, the thickness of the hollow fiber membrane 14 may be reduced and the mechanical strength and the permeation inhibition effect of impurities may be insufficient. .

(Upper holding member)
The upper holding member 15 has a casing which is open at the lower side and into which upper end portions of the plurality of hollow fiber membranes 14 are inserted from the lower side, and between the inner side wall of the casing and the outer peripheral face of the hollow fiber membranes 14 The resin composition is filled so as to leave an internal space communicating with the liquid collection pipe 18. More specifically, a bundle in which the upper end portions of the plurality of hollow fiber membranes 14 are bonded in advance by the resin composition is inserted into the casing, and further resin composition between the resin composition and between the resin composition and the inner wall of the casing The hollow fiber membrane 14 is fixed to the casing by the filling of the object.

  As a material of a casing, the resin composition which makes PTFE, polyvinyl chloride, polyethylene, an ABS resin etc. the main ingredients is mentioned, for example.

  Any resin composition may be used as long as it has high adhesion to the hollow fiber membrane 14 and the casing and can be cured in the casing. In particular, when using PTFE as the main component of the hollow fiber membrane 14, epoxy resin and polyurethane having high adhesiveness to PTFE and capable of reliably preventing the hollow fiber membrane 14 from falling off are used as the main component of the resin composition. preferable. By filling the casing with the resin composition, the space between the hollow fiber membrane 14 and the casing can be airtightly sealed, and the non-filtered treated liquid is mixed in with the filtered treated liquid from the outside Can be prevented.

(Lower side holding member)
The lower holding member 16 has a casing which is open at the upper side and into which lower end portions of the plurality of hollow fiber membranes 14 are inserted from the upper side. The lower holding member 16 is filled with a resin composition between the casing and the plurality of hollow fiber membranes 14 and between the plurality of hollow fiber membranes 14.

  The lower holding member 16 can be configured such that the upper holding member 15 is turned upside down. The material of the lower holding member 16 is the same as the material of the upper holding member 15. Further, the lower holding member 16 having no function of discharging the treated liquid does not form an internal space in the casing, and holds the lower end of the hollow fiber membrane 14 in such a way as to close the opening of the hollow fiber membrane 14 You may

(Connection member)
The connecting member 17 connects the upper holding member 15 and the lower holding member 16 which are vertically opposed to each other, so that the hollow fiber membrane 14 is not subjected to the load of the lower holding member 16. In addition, the connecting member 17 integrates the upper and lower holding members 15 and 16 facing each other and the bundle of hollow fiber membranes 14 disposed therebetween to facilitate handling (transportation, installation, replacement, etc.). Do.

  For example, a support rod made of metal, a casing (outer cylinder) made of resin, or the like can be used as the connection member 17.

(Collecting tube)
The liquid collection pipe 18 has a plurality of branch pipes 20 extending to the upper holding members 15 and a collecting pipe 21 for collecting the filtrate from each branch pipe 20 and discharging it out of the water tank 1.

  The collecting pipe 21 is held by the frame 19 of the liquid collecting pipe 18. Further, the liquid collection pipe 18 holds the upper holding member 15, and in turn, the hollow fiber membrane 14, the connecting member 17 and the lower holding member 16 by the branch pipe 20.

  In the pipe connected to the liquid collection pipe 18, the filtrate obtained by permeating the liquid to be treated from the outside of the hollow fiber membrane 14 to the lumen is discharged to the outside of the water tank 1 through the liquid collection pipe 18 A suction pump (not shown) for connection is connected.

(flame)
The frame 19 holds the collection tube 18 as described above, and holds the bundle of hollow fiber membranes 14 so as to extend in parallel and in the vertical direction by positioning the lower holding member 16 in the horizontal direction.

  The frame 19 has a support 22 mounted on the upper edge of the side wall 5 of the water tank 1 at the upper end, and the plurality of membrane modules 2 are suspended and held in the water tank 1. That is, the membrane module 2 is supported in the liquid to be treated in the water tank 1 without contacting the bottom wall 6 of the water tank 1. Thereby, the membrane module 2 is held so as not to interfere with the heater 3 and the air diffuser 4.

<Heater>
The heater 3 seals the heater opening 7 of the water tank 1 and the sealing portion 23 which can fix the heater 3 to the heater opening 7 and extends from the sealing portion 23 to the inside of the water tank 1 The heating unit 24 can be configured to heat the cleaning liquid stored in the water tank 1. Thus, the membrane module 2 is disposed in the water tank 1 by the heater 3 having the sealing portion 23 which can be attached to and detached from the heater opening 7 of the water tank 1 and the heat generating portion 24 disposed in the water tank 1. Since the heater 3 can be removed from the water tank 1 as it is, maintenance of the heater 3 can be easily performed.

  As shown in FIG. 2, the heaters 3 are preferably disposed directly under the bundle of hollow fiber membranes 14 of the membrane module 2. That is, the filtration device preferably includes the same number of heaters 3 as the number of rows of the bundle of hollow fiber membranes 14. As described above, by disposing the heaters immediately under the bundle of hollow fiber membranes 14, the hollow fiber membranes 14 can be brought into contact with the efficiently heated cleaning liquid by the convection of the heated cleaning liquid.

(Sealing part)
The sealing portion 23 is configured to seal the heater opening 7 of the water tank 1 and to fix the heater 3 to the heater opening 7. The sealing portion 23 of the present embodiment has a heater fixing flange 25 attached to the heater flange 10.

  The heater fixing flange 25 is attached to the heater flange 10 by bolts and nuts. Further, a packing for sealing a gap may be inserted between the heater fixing flange 25 and the heater flange 10.

(Heating part)
The heat generating portion 24 is preferably formed in a rod shape extending straight and horizontally into the water tank 1. Moreover, it is preferable that the heat-emitting part 24 has a circular cross section so that solid content in a to-be-processed liquid may not adhere easily on the surface.

  The length of the heat generating portion 24 is preferably slightly smaller than the width of the heat generating portion 24 of the water tank 1 in the extending direction in order to uniformly heat the cleaning liquid stored in the water tank 1.

  Such a heat generating portion 24 can be, for example, an electric heater in which a heat generating resistor is disposed in a protective tube (sheath). Since the heat generating portion 24 has a protective tube, maintenance for removing the solid content that has become stuck becomes easier.

  A commercially available flange heater can be used as the heater 3 having the sealing portion 23 and the heat generating portion 24 as described above.

<Diffusion tube>
The aeration pipe 4 has a plurality of aeration holes for discharging air to generate air bubbles, and a pipe 26 extending horizontally in the row direction of the bundle of hollow fiber membranes 14 of the membrane module 2 through the aeration pipe opening 8. In addition, it can be configured to have the aeration tube fixing flange 27 attached to the pipe 26 and attached to the aeration tube flange 12 to seal the aeration tube opening 8. Thus, since the air diffusion tube 4 can be removed from the water tank 1 with the membrane module 2 being disposed in the water tank 1 at the air diffusion tube opening 8 of the water tank 1, maintenance of the air diffusion tube 4 is easy. Can be done.

  As a material of the aeration pipe 4, for example, stainless steel, polypropylene, heat-resistant vinyl chloride and the like are preferable because they are excellent in heat resistance to the heat source of the heater 3 and have chemical resistance that does not easily deteriorate in the cleaning liquid.

  During the filtration operation of the filtration device, the air diffusion pipe 4 supplies air bubbles from below to the hollow fiber membranes 14 of the membrane module 2 and swings the hollow fiber membranes with the air bubbles to cause impurities in the liquid to be treated in the hollow fiber membranes 14. Can be prevented from adhering and blocking.

  In addition, during the cleaning of the filtration device, the air diffuser 4 supplies air bubbles from below to the hollow fiber membranes 14 of the membrane module 2 and swings the hollow fiber membranes with the air bubbles to attach impurities attached to the hollow fiber membranes 14. Promote the effect of removing.

  The air diffusing pipe 4 may be disposed in line with the heater 3 in the horizontal direction in order to reduce the height of the water tank 1, but it is preferable to dispose the air diffusing pipe 4 directly below the heat generating portion 24 of the heater 3. Thus, by disposing the aeration pipe 4 immediately below the heater 3, the convection of the cleaning liquid heated by the heater 3 can be promoted to enhance the cleaning effect. Further, by arranging the aeration pipe 4 immediately below the heater 3, air bubbles are brought into contact with the heat generating portion 24 to prevent the impurities in the cleaning liquid from adhering to the heat generating portion 24, and the heating efficiency of the cleaning liquid by the heater 3 The effect of suppressing the decrease can also be obtained.

<Method for cleaning hollow fiber membrane>
In the said filtration apparatus, washing | cleaning of the hollow fiber membrane 14 can be performed by the washing | cleaning method of the hollow fiber membrane which concerns on one Embodiment of this invention. The hollow fiber membrane cleaning method comprises the steps of: discharging the treatment liquid from the water tank 1 (treatment liquid discharge step); supplying the washing liquid to the water tank 1 (washing liquid supply step); and heating the washing liquid by the heater 3 It is possible to carry out by a method including the following steps (cleaning liquid heating step), discharging the cleaning liquid from the water tank 1 (cleaning liquid discharging step), and discharging the cleaning liquid remaining in the membrane module 2 (rinsing step).

(Process liquid discharge process)
In the liquid discharge step, the liquid stored in the water tank 1 is discharged from the discharge nozzle 9. At this time, since the bottom wall 6 is inclined, even if the solid content of the liquid to be treated in the lower part of the water tank 1 is concentrated and becomes a slurry, the liquid to be treated can be smoothly discharged.

(Cleaning solution supply process)
In the cleaning liquid supply process, the cleaning liquid is supplied to the water tank 1 to immerse at least the hollow fiber membranes 14 of the membrane module 2 in the cleaning liquid.

  The washing solution may be supplied directly to the water tank 1, but may be supplied through the liquid collection pipe 18 and thus through the hollow fiber membrane 14 using a pressure pump. That is, the washing solution may be supplied to the water tank 1 by back pressure washing the hollow fiber membrane 14.

  The cleaning solution can be selected according to the type of hollow fiber membrane 14 and the type of impurities of the liquid to be treated attached to hollow fiber membrane 14, etc. For example, acid, alkali, oxidizing agent, reducing agent, chelating agent And surfactants. As the acid, hydrochloric acid, sulfuric acid, nitric acid, citric acid, oxalic acid and the like are preferable. As the alkali, sodium hydroxide, potassium hydroxide and the like are preferable. As the oxidizing agent, sodium hypochlorite, chlorine dioxide, hydrogen peroxide, chloramine and the like are preferable. As the reducing agent, sodium bisulfite, sodium thiosulfate, sodium sulfite and the like are preferable.

(Washing solution heating process)
In the cleaning liquid heating step, the cleaning liquid is heated by the heater 3 to promote the dissolution or peeling of the impurities attached to the outer surface of the hollow fiber membrane 14 and the inside of the membrane by the cleaning liquid.

  In the cleaning solution heating step, air bubbles may be supplied from the air diffusion pipe 4 into the water tank 1. By supplying air bubbles from the air diffusion pipe 4 to the periphery of the heater 3, the convection of the heated cleaning solution can be accelerated to promote the cleaning of the hollow fiber membrane 14. In addition, the air bubbles released from the aeration tube 4 swing the hollow fiber membrane 14 to promote the separation of the deposit and help recovery of the filtration ability of the hollow fiber membrane 14. Furthermore, when the air bubbles released from the air diffusion pipe 4 come in contact with the surface of the heater 3, the impurities are fixed to the surface of the heater 3 to suppress the reduction of the heat transfer rate to the cleaning liquid. However, for example, when sodium hypochlorite is used as the cleaning solution, the effective chlorine in the cleaning solution may be vaporized by supplying air bubbles from the aeration pipe 4, and the cleaning effect may be deteriorated. It is preferable to supply air bubbles intermittently. In addition, when the surfactant is contained in the component in the cleaning fluid, a large amount of surfactant-derived bubbles may be generated by supplying air bubbles from the aeration pipe 4, and there is a possibility of overflowing from the upper part of the water tank 1, It is preferable to supply air bubbles not constantly but intermittently.

  The heating temperature (holding temperature) of the cleaning liquid can be set to, for example, 20 ° C. or more and 50 ° C. or less, which is set in consideration of the heat resistance temperature of each component of the membrane module 2 and the like. As a method of maintaining the cleaning solution at a constant temperature, a temperature detector (not shown) is installed in the water tank 1, and the heater 3 is controlled ON / OFF from the difference between the detected temperature of the temperature detector and the set temperature. It is preferable to control.

  The heating time (temperature holding time) of the washing solution may be selected so as to sufficiently recover the filtration capacity of the hollow fiber membrane 14, and can be, for example, 1 hour or more and 24 hours or less.

(Cleaning solution discharge process)
In the cleaning solution discharging process, the used cleaning solution stored in the water tank 1 is discharged from the discharging nozzle 9 after the cleaning solution heating process is completed. At this time, since the bottom wall 6 is inclined, the used cleaning fluid can be smoothly discharged even if the solid content in the used cleaning fluid in the lower part of the water tank 1 is precipitated.

(Rinse process)
In the rinse step, the membrane module 2 is backwashed with the clear liquid using a pressure pump to wash away the cleaning solution remaining on the outer surface and the inside of the hollow fiber membrane 14 and discharged from the discharge nozzle 9.

  In this rinse step, it is preferable that the clear liquid used for reverse pressure washing does not contain any impurities that clog the membrane, and for example, tap water, industrial water, filtrate during filtration operation, etc. can be used.

<Advantage>
The said filtration apparatus can heat the washing | cleaning liquid stored in the water tank 1 by providing the heater 3 arrange | positioned under the membrane module 2 in a water tank. Thereby, even in a low temperature environment, it is possible to immerse the plurality of hollow fiber membranes 14 in the heated cleaning liquid and efficiently wash it, thereby recovering the filtering ability. That is, the hollow fiber membrane cleaning method can efficiently clean the hollow fiber membrane 14.

Other Embodiments
It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is not limited to the configurations of the above embodiments, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. Ru.

  In the filtration device, the sealing portion of the heater is, in addition to the flange as in the above embodiment, other known connections used for connection of pipelines and sealing of openings such as tanks, such as ferrules, screws, cam locks, etc. It may have a structure.

  In the filtration device, the opening of the water tank may be provided with a configuration that can be airtightly connected to the sealing portion in accordance with the structure of the sealing portion of the heater. As an example, when the sealing portion of the heater is a flange as in the above embodiment, the opening of the water tank may be provided with a pad flange without a nozzle, a flange with a stud and the like.

  In the filtration device, the membrane module may be configured to be suspended in the water tank regardless of the frame, for example by a water collection pipe or a pipe extending from the water collection pipe. In addition, the filtration device may have a configuration in which the water tank holds the membrane module in a suspended state.

  In the filtration device, the heater does not penetrate the side wall of the water tank, and may be disposed below the membrane module in the water tank, for example, by being attached to a frame or the like.

  In the filtration device, one or more pairs of heaters may be respectively attached to opposite side walls of the water tank so as to be in a butt state.

  In the filtration device, the air diffusion pipe is not an essential component, and may not be penetrated through the side wall of the water tank, and may be disposed below the membrane module in the water tank by being attached to, for example, a frame.

  In the method of cleaning a hollow fiber membrane, a cleaning solution which has been heated in advance may be supplied. In particular, when the hollow fiber membrane is subjected to reverse pressure cleaning with a cleaning solution, the cleaning effect can be improved by supplying a heated cleaning solution.

  The filtration device can be widely used as a filtration device for filtering various liquids.

DESCRIPTION OF SYMBOLS 1 Water tank 2 Membrane module 3 Heater 4 Diffuser 5 Side wall 6 Bottom wall 7 Heater opening 8 Diffuser opening 9 Discharge nozzle 10 Heater flange 11 Heater nozzle 12 Diffuser flange 13 Diffuser nozzle 14 Hollow fiber membrane 15 Upper side holding member 16 Lower side holding member 17 Connection member 18 Liquid collection pipe 19 Frame 20 Branch pipe 21 Collecting pipe 22 Support part 23 Sealing part 24 Heating part 25 Heater fixing flange 26 Pipe 27 Diffuser fixing flange

Claims (7)

A water tank for storing the liquid to be treated;
A membrane module having a plurality of hollow fiber membranes which are vertically aligned, and disposed in the water tank;
And a heater disposed below the membrane module in the water tank.   The filtration device according to claim 1, wherein the heater has a sealing portion sealing an opening formed in a lower portion of the side wall of the water tank and a heat generating portion extending from the sealing portion.   The filtration apparatus according to claim 1 or 2, wherein the water tank has an inclined bottom wall.   The filtration device according to any one of claims 1 to 3, wherein the filtration joule is suspended and held in the water tank.   The filtration apparatus according to any one of claims 1 to 4, further comprising an air diffusion pipe disposed below the membrane module in the water tank.   The filtration device according to claim 5, wherein the air diffusion pipe extends horizontally through an opening formed in a lower side wall of the water tank. A water tank for storing the liquid to be treated;
A membrane module having a plurality of hollow fiber membranes which are vertically aligned, and disposed in the water tank;
A heater disposed below the membrane module in the water tank;
A method of washing a hollow fiber membrane of the membrane module of a filtration apparatus comprising a diffuser provided below the membrane module in the water tank with a cleaning liquid,
A cleaning solution supply step of supplying a cleaning solution into the water tank;
And a cleaning solution heating step of heating the cleaning solution with the heater and maintaining the cleaning solution at a constant temperature while generating air bubbles from the aeration tube and convecting the cleaning solution, and cleaning the hollow fiber membrane.

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