JP5660473B2 - Water purifier and cleaning method thereof - Google Patents

Description

 The present invention relates to a water purifier that purifies tap water and the like.

  Conventionally, water purifiers have been used to purify tap water due to pollution of water resources and demand for delicious water. As such a water purifier, a water purifier having a function of removing tap water odor, mold odor, trihalomethane, etc. by an adsorbent such as activated carbon, and removing bacteria, turbid components, etc. by a porous hollow fiber membrane is known. .

  As an example of such a water purifier, there is a faucet directly connected water purifier 1 as shown in FIG. The water purifier 1 is attached to the faucet 2 using an adapter 3 and a fixing ring 4, and the raw water and the purified water are switched by a switching mechanism unit incorporated in the water purifier 1 by operating the switching lever 5. Is possible. A water purification cartridge is accommodated in the cartridge cover 7 of the water purifier 1. In this water purifier 1, when the switching lever 5 is switched to the purified water side and the raw water is caused to flow from the faucet 2, the raw water is guided to the water purification cartridge by the switching mechanism and passes through the filtering material inside to be purified. After that, it flows downward from the purified water outlet 9.

  FIG. 4 is a cross-sectional view showing an example of a water purification cartridge used in the water purifier 1. This water purification cartridge 6 is provided with a sintered filter 11 on the rear end surface, a cylindrical case 13 having a lid portion having a water purification outlet 12 on the front end surface, and the inside of the case 13 on the side of the sintered filter 11 and the water purification outlet. A partition plate 14 divided into 12 sides, an adsorbent 15 filled on the sintered filter 11 side of the case 13, and a plurality of hollow fiber membranes 16 fixed by a potting material 17 on the water purification outlet 12 side of the case 13. To do. Here, the hollow fiber membrane 16 is fixed to the case 13 by a potting material 17 so that both ends of the plurality of hollow fiber membranes 16 bent in a U-shape maintain the open state of the end portions of the hollow fiber membrane 16. .

  In such a water purification cartridge 6, the raw water is introduced into the water purification cartridge 6 through the sintered filter 11. The raw water introduced into the water purification cartridge 6 passes through the adsorbent 15, the partition plate 14, and the hollow fiber membrane 16 in this order, and is purified during this passage. The purified water obtained by purifying the raw water is discharged from the purified water outlet 12 of the purified water cartridge 6 to the outside of the purified water cartridge 6.

  When purification of raw water is carried out for a while with the water purifier 1 equipped with the water purification cartridge 6, bacteria and turbid components are formed on the surface (primary side) of the hollow fiber membrane 16 depending on the degree of contamination of the raw water and the amount of treated water. Etc. adhere and accumulate, and the hollow fiber membrane 16 becomes clogged. In such a state, the function of the hollow fiber membrane 16 can be recovered only by a method of cleaning the surface of the hollow fiber membrane 16.

  However, the hollow fiber membrane 16 is fixed in the case 13 by the potting material 17, and it is extremely difficult to clean the surface of the hollow fiber membrane 16. Therefore, when the hollow fiber membrane 16 is clogged and the function of the hollow fiber membrane 16 is remarkably deteriorated, the water purification cartridge 6 is replaced with a new one even if there is still a margin in the removal capacity of the adsorbent 15. However, it was a factor that significantly increased the running cost of the purification process by the water purifier 1.

In order to prevent clogging of the hollow fiber membrane, Japanese Patent Application Laid-Open No. 8-89948 discloses a method of performing reverse liquid flow from the secondary side of the hollow fiber membrane to remove obstructions on the surface of the hollow fiber membrane. ing. However, since this method feeds dirty raw water as it is from the secondary side of the hollow fiber membrane, the inner surface of the hollow fiber membrane may be contaminated.
Japanese Laid-Open Patent Publication No. 8-84999 discloses a method of arranging a plurality of hollow fiber membrane modules and backwashing another hollow fiber membrane module using the filtered water of one hollow fiber membrane module. . However, since this method requires a plurality of hollow fiber membrane modules, there is a problem in that the filtration part becomes large and the number of parts increases.

  An object of the present invention is to provide a water purification cartridge and a water purifier capable of washing and recovering a hollow fiber membrane having a reduced function and suppressing a running cost of purification treatment of raw water.

That is, the first gist of the present invention is a water purifier having a hollow fiber membrane module that is fixed to one end of a cylindrical case with the end portion of the hollow fiber membrane kept open. The membrane module has a hollow fiber membrane filling rate of 20 to 60%, and the cylindrical case is provided with a cleaning liquid supply port and a cleaning liquid discharge port for cleaning the outer surface of the hollow fiber membrane, from the cleaning liquid supply port, An amount of the chemical solution that fills the cylindrical case is supplied, the cleaning liquid discharge port is provided on a side surface of the cylindrical case near the hollow fiber membrane fixing portion, and a cleaning opening / closing valve is provided at the cleaning liquid discharge port. A water purifier in which a plurality of the hollow fiber membrane modules are provided in parallel, and the other hollow fiber membrane modules can be filtered when one hollow fiber membrane module is washed .
When the hollow fiber membrane filling rate of the hollow fiber membrane module, that is, the total ratio of the hollow fiber membrane cross-sectional area (outer diameter base) to the inner cross-sectional area of the cylindrical case is too high, the deposits that have entered between the hollow fiber membranes Is difficult to remove by washing, while on the other hand, if it is too low, the collection efficiency is lowered and the filtration capacity is lowered, so it is necessary to make it 20 to 60%, preferably 30 to 50%, preferably 35 to 47.5%. Is more preferable. At this time, the supply amount of cleaning water used for cleaning is preferably 0.01 to 5 L / cm 2 · min per inner diameter reference cross-sectional area of the cylindrical case, because the membrane surface can be effectively cleaned, 0.03-3.5 L / cm 2 · min is more preferable, and 0.1-1.5 L / cm 2 · min is more preferable.
The cleaning liquid supply port is communicated with the chemical liquid tank, and a pump for feeding the chemical liquid is provided between the cleaning liquid supply port and the chemical liquid tank, or the liquid level of the chemical liquid tank is the hollow fiber membrane module. It is a water purifier, which is located higher than.
In addition, when a plurality of the hollow fiber membrane modules are provided in parallel to allow filtration of other hollow fiber membrane modules when washing one hollow fiber membrane module, the filtration can be performed even during washing. Is preferable because the filtration life can be extended as compared with the case of one.
Moreover, it is preferable to dispose a prefilter upstream of the hollow fiber membrane module because the lifetime of the hollow fiber membrane can be further extended. In addition, it is preferable to dispose an adsorbent layer upstream of the hollow fiber membrane module because more various water purification is possible.
Further, it is more preferable that the cleaning liquid supply port is a raw water supply port of the hollow fiber membrane module because of a simple configuration.
In addition, it is preferable to have a means for measuring at least one of the amount of filtered water, the filtration flow rate, and the filtration pressure because filtration can be performed while washing and can be used as an index for recovering filterability.

Further, the second gist of the present invention is that the end portion of the hollow fiber membrane is fixed to one end of the cylindrical case while keeping the open state, and the filling rate of the hollow fiber membrane is 20 to 60%. upon have a hollow fiber membrane module, provided with the hollow fiber membrane module in parallel a plurality, and washed during the cleaning of one of the hollow fiber membrane module allows filtration of other hollow fiber membrane module was water purifier and tubular A cleaning method for a water purifier in which a chemical solution is supplied to a case to fill the cylindrical case in order to clean the outer surface of the hollow fiber membrane, and the chemical solution is discharged after being held for a predetermined time.
Moreover, after discharging | emitting a chemical | medical solution, it is the washing | cleaning method of the above-mentioned water purifier discharged | emitted from a washing | cleaning liquid discharge port, after supplying raw | natural water further from a washing | cleaning liquid supply port, applying a water flow to the hollow fiber membrane surface.
At this time, when the chemical solution is an aqueous solution containing any one of hydrochloric acid, citric acid, acetic acid, household detergent, and bleached powder, it can be effectively washed and easily obtained.
Further, the third gist of the present invention is to supply raw water to the washing water supply port, apply a water flow to the hollow fiber membrane surface, perform filtration while simultaneously washing the hollow fiber membrane while discharging from the washing liquid discharge port, A cleaning method for a water purifier, which measures at least one of the amount of filtered water, the filtration flow rate, and the filtration pressure from the start of washing, and stops washing when the amount of filtered water or the filtration flow rate reaches a predetermined amount.
It is more preferable to measure at least one of an integrated filtration time, an integrated filtration flow rate, a filtration flow rate, and a filtering pressure, and automatically perform cleaning when any one of them reaches a preset value.

As described above, the water purifier of the present invention is provided with a cleaning liquid supply port and a cleaning liquid discharge port for cleaning the outer surface of the hollow fiber membrane in the cylindrical case, so that raw water or chemical liquid is supplied from the cleaning liquid supply port. Since the cleaning liquid can be supplied and discharged from the cleaning liquid discharge port, the closed hollow fiber membrane can be regenerated and the water purification cartridge can be used for a long period of time, so that the running cost of the water purification treatment can be suppressed.

The present invention will be described in detail below.
FIG. 1 is a cross-sectional view showing an example of a hollow fiber membrane module used in the water purifier of the present invention. In the figure, symbol FI indicates a flow meter, and PI indicates a pressure gauge.
The hollow fiber membrane module 10 has a cylindrical shape in a state where both ends of a plurality of hollow fiber membranes 16 bent in a U shape are converged by a potting material 17 so as to keep the open state of the end portions of the hollow fiber membrane 16. The module cap 23 in which the purified water outlet 12 is formed is arranged at the filtered water outlet and is roughly configured.
Here, the hollow fiber membrane case 22 is shaped like a teacup by shortening the length of the hollow fiber membrane case in FIG. 1, but it may be longer than the length of the hollow fiber membrane, It may be a case with a hole for water passage. At this time, as shown in the figure, the protective net 18 is attached to improve the handleability. However, the protective net 18 may be omitted.
The hollow fiber membrane module 10 is attached to the module cap 23 via the elastic body 19. However, the hollow fiber membrane 16 may be fixed to the module cap 23 from the beginning with the potting material 17.

  Here, the cylindrical case 31 is provided with a cleaning liquid supply port and a cleaning liquid discharge port, and after the cleaning liquid supplied from the cleaning liquid supply port is applied to the outer surface of the hollow fiber membrane, it is discharged from the cleaning liquid discharge port to the hollow fiber membrane surface. Occluded substances such as accumulated bacteria and turbid components can be peeled off from the surface of the hollow fiber membrane and discharged out of the module, so that the filtration function of the hollow fiber membrane can be recovered.

At this time, as shown in FIG. 1, when the cleaning liquid discharge port 34 is provided on the side surface in the vicinity of the hollow fiber membrane fixing portion of the cylindrical case 31, the cleaning liquid can be applied to the entire hollow fiber membrane, The direction of the water flow of the cleaning liquid changes at the root portion that is most likely to be blocked, and as a result, the root portion can be effectively cleaned, which is preferable.
If the number of cleaning liquid discharge ports 34 is one, cleaning is possible, but two or more cleaning liquid discharge ports 34 may be provided.

  The cleaning liquid supply port may be provided on the side surface of the cylindrical case 31 similarly to the cleaning liquid discharge port 34. However, it is preferable to use the cleaning liquid supply port also as the raw water supply port 35 because the configuration can be simplified. That is, as shown in FIG. 1, if a cleaning opening / closing valve 38 is provided at the cleaning liquid discharge port 34, when performing filtration, the cleaning opening / closing valve 38 is closed and the raw water is supplied from the raw water supply port 35. After being filtered by the hollow fiber membrane 16, it flows out from the purified water outlet 12.

Further, when cleaning is performed, the cleaning open / close valve 38 is opened, and when raw water is supplied from the cleaning liquid supply port 40 that also serves as the raw water supply port 35, the raw water is discharged from the cleaning liquid discharge port 34. Can be washed. At this time, the pressure required for the filtration through the hollow fiber membrane 16 is higher than the pressure required for discharging water from the cleaning liquid discharge port 34, and much of the raw water is discharged from the cleaning liquid discharge port 34. Since the amount of water to be filtered is small, it is not necessary to close the filtered water outlet.
At this time, since the adhering matter deposited on the surface of the hollow fiber membrane is washed away by washing and the filterability is restored, at least one of the filtration water amount, the filtration flow rate, and the filtration pressure is measured to filter the hollow fiber membrane. It can also be used as an index of sex recovery. Specifically, we installed an impeller type, positive displacement type, electromagnetic type flow meter, velocimeter, and pressure gauge to measure the accumulated filtered water amount, filtration flow rate, and filtration pressure from the start of washing. What is necessary is just to make it stop washing | cleaning at the time of reaching the value preset according to the conditions to be used.
In order to perform these controls automatically, an electromagnetic measuring device is suitable.

  It is also possible to provide the raw water supply port 35 on the side surface of the cylindrical case contrary to the configuration of FIG. In this case, cleaning can be performed by branching the raw water supply line to discharge the cleaning liquid or by providing the cleaning liquid discharge port 34 separately from the raw water supply port 35.

  Examples of the hollow fiber membrane 16 include cellulose, polyolefin (polyethylene, polypropylene), polyvinyl alcohol, ethylene / vinyl alcohol copolymer, polyether, polymethyl methacrylate (PMMA), polysulfone, poly Those made of various materials such as acrylonitrile, polyfluorinated ethylene (Teflon (registered trademark)), polycarbonate, polyester, polyamide, and aromatic polyamide can be suitably used. Among these, in view of the strong elongation, bending resistance, cleanability, handleability, chemical resistance, etc. of the membrane, a polyolefin-based hollow fiber membrane such as polyethylene or polypropylene is preferred.

Although not particularly limited, the hollow fiber preferably has an outer diameter of 20 to 2000 μm, a pore diameter of 0.01 to 2 μm, a porosity of 20 to 90%, and a film thickness of 5 to 300 μm.
The hollow fiber membrane length is preferably 10 mm or more, and more preferably 20 mm or more in order to allow the yarn to sway and perform effective cleaning. On the other hand, if the length is too long, the utilization efficiency of the hollow fiber membrane is lowered, so that it is preferably 300 mm or less, and more preferably 200 mm or less.

  As the potting material 17, for example, a fixing resin made of urethane resin, epoxy resin, polyolefin resin, or the like can be used. As the material of the cylindrical case 31, it is preferable to use metals (such as stainless steel) and plastics in consideration of workability and the like.

In addition, since hot water of 80 ° C. or higher supplied from a water heater can be directly used, the softening point of polypropylene, polyphenylene ether, polyoxymethylene, polycarbonate, ABS resin, etc. has heat resistance of 80 ° C. or higher. More preferably, plastic is used.
The cylindrical case 31 is formed of a transparent or translucent member, so that the internal state such as dirt on the hollow fiber membrane 16 can be confirmed.

  In addition, as shown in FIG. 2, when a plurality of hollow fiber membrane modules are provided in parallel and configured to allow filtration of other hollow fiber membrane modules 10 when cleaning one hollow fiber membrane module 10 モ ジ ュ ー ル, Moreover, it is preferable because filtration can be performed and the filtration life can be further extended as compared with the case of one hollow fiber membrane module.

  FIG. 2 is an example in which two hollow fiber membrane modules are provided in parallel. When performing filtration, filtration may be performed using only one of the hollow fiber membrane modules or may be performed using two hollow fiber membrane modules at the same time. As in FIG. 1, symbol FI indicates a flow meter, and PI indicates a pressure gauge.

  When cleaning is performed, the opening / closing valve 38 for cleaning provided in the cleaning liquid discharge port 34 of one hollow fiber membrane module is closed, and the opening / closing valve 38 for cleaning provided in the cleaning liquid discharge port 34 of the other hollow fiber membrane module is closed. Release the bag. When raw water is supplied to both of the hollow fiber membrane modules, filtration is performed by the hollow fiber membrane 16 in one hollow fiber membrane module to obtain filtered water from the outlet 12 of the filtered water, and in the other hollow fiber membrane module, the washing liquid is discharged. The cleaning liquid is discharged from the outlet 34 and the hollow fiber membrane 16 is cleaned.

  If the pre-filter 41 that removes relatively large foreign matters such as coarse dust, sand, and iron rust in the raw water is detachably provided on the upstream side of the hollow fiber membrane module, the burden on the hollow fiber membrane is reduced, and the hollow fiber membrane is reduced. This is preferable because the lifetime of the can be increased. As the prefilter 41, a sintered filter made of a porous powder sintered body, a non-woven fabric, a mesh, or the like can be suitably used.

  Examples of the prefilter material include polyolefin resins such as polyethylene and polypropylene, resin materials such as polystyrene resin, acrylic resin, and fluorine resin, C, Si, Mn, P, S, Cr, Mo, Nb, Ta, B, Examples thereof include inorganic and metal materials such as V, Ni, Cu, Al, Ti, Fe, Co, and alloys thereof. Among them, polyolefin resin is suitably used because it is lightweight when used as a sintered filter, can be recycled, does not generate harmful substances even during incineration, and can easily control the pore diameter.

  Further, it is preferable that the adsorbent layer 42 is detachably provided upstream of the hollow fiber membrane module because more various water can be purified. Examples of the adsorbent include a powder adsorbent, a granular adsorbent obtained by granulating the powder adsorbent, and a fibrous adsorbent. Examples of such adsorbents include natural product-based adsorbents (natural zeolite, silver zeolite, acidic clay, etc.), synthetic-based adsorbent materials (synthetic zeolite, antibacterial zeolite, bacterial adsorption polymer, phosphorus ore, molecular sieve, Inorganic adsorbents such as silica gel, silica alumina gel adsorbent, porous glass, etc .; powdered activated carbon, fibrous activated carbon, block activated carbon, extruded activated carbon, molded activated carbon, molecular adsorption resin, synthetic granular activated carbon, synthesis Well-known materials such as physical fibrous activated carbon, ion-exchange resin, ion-exchange fiber, chelate resin, chelate fiber, highly water-absorbent resin, highly water-absorbent fiber, oil-absorbent resin, and oil absorbent .

  Among them, activated carbon having excellent adsorptive power for organic compounds such as residual chlorine, mold odor, and trihalomethane in water to be treated is preferably used. An ion exchange resin is suitably used for adjusting the hardness (Ca, Mg), removing lead, and removing nitrate and nitrite nitrogen. Zeolite is preferably used for removing arsenic. A chelating agent is preferably used for removing boron and fluorine. Further, as the adsorbent, a porous molded body formed by bonding adsorbent powder, granules and the like with a binder may be used. Two or more kinds of adsorbents may be mixed or laminated.

  Activated carbon includes vegetable matter (wood, cellulose, sawdust, charcoal, coconut shell charcoal, bare ash, etc.), coal (peat, lignite, brown coal, bituminous coal, anthracite, tar, etc.), petroleum (oil residue, sulfuric acid, etc.) Sludge, oil carbon, etc.), pulp waste liquid, synthetic resin, etc., carbon activation (steam, carbon dioxide, air, etc.), chemical activation (calcium chloride, magnesium chloride, zinc chloride, phosphoric acid, sulfuric acid, Caustic soda, KOH, etc.). Examples of the fibrous activated carbon include those obtained by carbonizing and activating a precursor made from polyacrylonitrile (PAN), cellulose, phenol, and coal-based pitch.

  The hollow fiber membrane can be washed using a chemical solution having a strong detergency in addition to the raw water. When a chemical solution is used, cleaning can be performed effectively by bringing the hollow fiber membrane into contact with the chemical solution for a predetermined time. In this case, if the hollow fiber membrane module shown in FIG. 1 is used, the cleaning opening / closing valve 38 of the cleaning liquid discharge port 34 is closed, the raw water opening / closing valve 36 is closed, the cleaning liquid supply opening / closing valve 39 is opened, and the raw water supply port is opened. A chemical solution is supplied from a cleaning solution supply port 40 that also serves as 35. The hollow fiber membrane can be washed by leaving the chemical solution in contact with the hollow fiber membrane 16 by leaving it for a predetermined time and then discharging the chemical solution by opening the valve 38 of the washing fluid outlet 34.

The method for supplying the chemical liquid is not particularly limited, and for example, the liquid may be fed using a pump, or the liquid level of the chemical liquid tank may be arranged higher than the hollow fiber membrane module and fed by a water head difference. it can.
The required amount of the chemical solution may be sent in such an amount that the inside of the cylindrical case is filled with the chemical solution.

The contact time with the chemical solution may be set as appropriate depending on the type and concentration of the chemical solution to be used, but a time of 5 to 60 minutes is preferable for removing the clogging substance on the surface of the hollow fiber membrane.
The kind of the chemical solution is preferably an aqueous solution containing any one of hydrochloric acid, citric acid, acetic acid, household detergent, and bleached powder because it has a high cleaning effect and can be obtained easily and inexpensively.

  In the cleaning with the chemical solution, the required amount of the chemical solution may be supplied at a time, or may be continuously supplied during the cleaning.

  If filtration is performed immediately after washing with a chemical solution, the chemical solution may be mixed into the filtrate. Therefore, it is preferable to appropriately wash the hollow fiber membrane module. In that case, if the raw water is supplied from the cleaning liquid supply port provided in the hollow fiber membrane module and the cleaning liquid is discharged from the cleaning liquid discharge port, the surface of the hollow fiber membrane can be cleaned while cleaning the chemical solution. Is more preferable because it becomes higher. Washing with raw water may be performed under the conditions described above.

When the hollow fiber membrane is contaminated, the appropriate washing is determined by measuring at least one of the total filtration time, the total filtration flow rate, the filtration flow rate, and the filtration pressure, and any one of them is set to a preset value. It is preferable to perform cleaning automatically when it arrives, because the user does not need to perform the cleaning operation each time.
In automatic cleaning, an automatic control system can be assembled by using an electronic pressure gauge and flow meter.

It is sectional drawing which shows an example of the hollow fiber membrane module used for the water purifier of this invention. It is sectional drawing which shows an example which provided multiple hollow fiber membrane modules used for the water purifier of this invention. It is a perspective view which shows an example of a water purifier. It is sectional drawing which shows an example of the conventional cartridge.

1 water purifier
2 faucet
3 Adapter
4 Fixing ring
5 Switching lever
6 Water purification cartridge
7 Cartridge cover
9 Clean water outlet
10 Hollow fiber membrane module
11 Sintered filter
12 Water purification outlet
13 cases
14 Partition plate
15 Adsorbent
16 Hollow fiber membrane
17 Potting material
18 Protective net
19 Elastic body
20 Elastic body
21 Fitting groove
22 Case for hollow fiber membrane
23 Module cap
24 Mating protrusion
31 Tubular case
32 cylindrical cap
33 Fixed band
34 Cleaning liquid outlet
35 Raw water supply port
36 Raw water open / close valve
37 Water purification valve
38 Open / close valve for cleaning
39 Cleaning liquid supply open / close valve
40 Cleaning liquid supply port
41 Prefilter
42 Adsorbent layer

Claims (11)

A water purifier having a hollow fiber membrane module that is fixed to one end of a cylindrical case with the end portion of the hollow fiber membrane kept open, and the hollow fiber membrane module has a hollow fiber membrane filling rate of 20 to The cylindrical case is provided with a cleaning liquid supply port and a cleaning liquid discharge port for cleaning the outer surface of the hollow fiber membrane, and an amount of chemical liquid that fills the cylindrical case is supplied from the cleaning liquid supply port. The cleaning liquid discharge port is provided on a side surface of the cylindrical case near the hollow fiber membrane fixing portion, the cleaning liquid discharge port is provided with a cleaning on-off valve , and a plurality of the hollow fiber membrane modules are provided in parallel. A water purifier that enables filtration of other hollow fiber membrane modules when washing one hollow fiber membrane module . The cleaning liquid supply port is in communication with a chemical liquid tank, and a pump for feeding the chemical liquid is provided between the cleaning liquid supply port and the chemical liquid tank, or the liquid level of the chemical liquid tank is more than that of the hollow fiber membrane module. The water purifier of Claim 1 arrange | positioned in the high place. The water purifier according to claim 1 or 2 , wherein a prefilter is disposed upstream of the hollow fiber membrane module. The water purifier according to any one of claims 1 to 3 , wherein an adsorbent layer is disposed upstream of the hollow fiber membrane module. The water purifier according to any one of claims 1 to 4, wherein the cleaning liquid supply port is a raw water supply port of the hollow fiber membrane module. The water purifier according to any one of claims 1 to 5, further comprising means for measuring at least one of a filtered water amount, a filtration flow rate, and a filtration pressure. While the distal end of the hollow fiber membrane is kept open state, it is fixed to one end of the cylindrical case, the filling rate of the hollow fiber membranes have a hollow fiber membrane module is 20% to 60%, the hollow fibers When cleaning a water purifier that is provided with a plurality of membrane modules in parallel and allows filtration of other hollow fiber membrane modules when cleaning one hollow fiber membrane module, the outer surface of the hollow fiber membrane is cleaned in the cylindrical case A cleaning method for a water purifier in which a chemical solution is supplied in an amount that fills the cylindrical case, and is held for a predetermined time, and then the chemical solution is discharged. The method for cleaning a water purifier according to claim 7 , wherein after the chemical liquid is discharged, raw water is further supplied from the cleaning liquid supply port, a water flow is applied to the hollow fiber membrane surface, and then discharged from the cleaning liquid discharge port. The method of cleaning a water purifier according to claim 8 , wherein the chemical solution is an aqueous solution containing any one of hydrochloric acid, citric acid, acetic acid, household detergent, and bleached powder. Supply raw water to the cleaning liquid supply port, apply water flow to the surface of the hollow fiber membrane, clean the hollow fiber membrane while discharging it from the cleaning liquid discharge port, and perform filtration at the same time. The cleaning method according to claim 9 , wherein at least one of the pressures is measured, and the cleaning is stopped when the amount of filtered water or the filtration flow rate reaches a preset value. The purified water according to any one of claims 7 to 10 , wherein at least one of an integrated filtration time, an integrated filtration flow rate, a filtration flow rate, and a filtering pressure is measured, and cleaning is automatically performed when any one of them reaches a preset value. How to clean the vessel.

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