JPH11207333A - Water purifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sanitarily keep a hollow fiber membrane module and the inside of a water feed path. SOLUTION: In the water purifying process, a water storage tank 1, a hollow fiber membrane module 9 and a water feed port 17 are communicated with each other, and a water feed pump 15 is driven. The water in the water storage tank 1 is purified by filtering through the hollow fiber membrane module 9, and is fed from the water feed port 17. On the other hand, in a washing process, water is stored in a heating part 20, and the water is heated with a heater 21 and the heated water is passed through the hollow fiber membrane module 9 and the water feed path 18. Thus, the hollow fiber membrane 9 and the inside of the water feed path 18 are sterilized and the hollow fiber membrane module 9 and the inside of the water feed path 18 are kept sanitarily.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water purifier using a hollow fiber membrane module, and more particularly to a structure for disinfecting microorganisms that are filtered and stay in the hollow fiber membrane module. .

[0002]

Conventionally, this type of water purifier has a water tank, a discharge port for discharging water in the water tank to the outside of the water tank, and a water supply port for supplying water to the outside of the water tank. It has a water supply pipe, a water supply pump connected between the discharge port and the water supply port, and a hollow fiber membrane module. If these hollow fiber membrane modules are used, fine solids and bacteria in water can be filtered, so that water can be purified and sterilized. Then, for example, Japanese Patent Application Laid-Open No. 7-2658
No. 73 discloses a water purification device in which a water supply pipe is made of an antibacterial material. With the water purification device of the present invention configured as described above, it is possible to prevent the propagation of various bacteria in the water supply pipe, and to achieve an effect of keeping the water supply pipe sanitary.

However, since a general hollow fiber membrane module itself has no antibacterial action, there is a risk that various bacteria may survive and proliferate in the water remaining in the hollow fiber membrane module, which is not hygienic. Was. In addition, harmful microorganisms (for example, cryptosporidium, etc.), which have become a problem in recent years
Has a high resistance to chlorine and antibacterial materials, and thus may survive and proliferate even in a water supply pipe using antibacterial materials. If these bacteria are discharged to the outside of the water purification device for any reason such as backflow of water, there is a risk that they may enter the body, which is unsanitary.

[0004] In view of the above problems, an object of the present invention is to provide a water purification device capable of keeping the inside of a hollow fiber membrane module and a water supply passage sanitary.

[0005]

According to a first aspect of the present invention, there is provided a water purification apparatus, comprising: a water storage tank; a discharge port provided in the water storage tank; A provided water supply port, a water supply path connecting the discharge port and the water supply port,
In a water purification device having a water supply pump and a hollow fiber membrane module provided in the middle of the water supply path, a heating unit formed with the heat resistant resin and having the hollow fiber membrane module connected to the water storage tank and the water supply path. A heater for heating water in the heating section, a washing path connected to the water supply path via a switching valve to send heated water from the heating section to the water supply path, and a switching valve for the water supply path. And a drainage channel connected through the hollow fiber membrane module for discharging hot water that has passed through the hollow fiber membrane module.

According to the structure of the first aspect, in the water purification step, the water in the water storage tank is hollowed out by connecting the water storage tank, the hollow fiber membrane module and the water supply port with the water supply path and driving the water supply pump. The water is filtered and purified by a thread membrane module and supplied from a water supply port. In the washing process,
Water is stored in the heating section, the water is heated by a heater to generate hot water, and the hot water is passed through the hollow fiber membrane module and the water supply passage to sterilize the inside of the hollow fiber membrane module and the water supply passage. Hot water that has passed through the hollow fiber membrane module
It is discharged outside from the drainage channel.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, a control circuit for controlling the switching valve and the heater is provided, and a water level sensor is provided in the water storage tank. While the control circuit performs water purification by the hollow fiber membrane module while the water level sensor detects a water level that is equal to or higher than a predetermined value, and the hollow fiber when the water level sensor detects a water level that is equal to or lower than a predetermined value. It operates to wash the membrane module with hot water.

According to the configuration of claim 2, when the water level in the water storage tank detected by the water level sensor is equal to or higher than a predetermined value,
Water is purified by the hollow fiber membrane module, and when the water level in the water storage tank is equal to or lower than a predetermined value, the hollow fiber membrane module is washed with hot water.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. 1 is a water tank in which a water level line 2 is engraved on the upper part. A water level sensor 3 for detecting a water level in the water storage tank 1 is provided on a lower side wall of the water storage tank 1, and a discharge port 4 is formed at a bottom of the water storage tank 1. A water supply pipe 5 is connected to the discharge port 4. A water supply pipe 8 is connected to the water supply pipe 5 via a switching valve 7 such as an electromagnetic valve operated by a control circuit 6.
One end of a hollow fiber membrane module 9 containing a large number of hollow fiber membranes (not shown) is connected to the water supply pipe 8. The hollow fiber membrane has heat resistance, for example, polysulfone resin, polyimide resin,
A resin such as a polyether sulfone resin is used. The other end of the hollow fiber membrane module 9 has a water supply pipe 10
Is connected. The water supply pipe 10 includes a control circuit 6
Water supply pipe 12 through a switching valve 11 such as an electromagnetic valve operated by
The water supply pipe 12 is further connected to a water supply pump 15 including an electric motor 13 and a pump vortex chamber 14 driven by the electric motor 13. The pump vortex chamber 14 of the water supply pump 15 is provided with the water level line 2 of the water storage tank 1.
It is provided at a lower position. Further, a water supply pipe 16 is connected to the pump vortex chamber 14, and a distal end of the water supply pipe 16 serves as a water supply port 17. The water supply pipes 5, 8, 10, 12, and 16 form a water supply path 18 that connects the discharge port 4 and the water supply port 17. A heating unit 20 is connected to the switching valve 7 via a water pipe 19.
Is switched, either the water supply pipe 5 or the water supply pipe 19 communicates with the water supply pipe 8.
The heating unit 20 includes a heater 21 as a heating unit controlled by the control circuit 6 and a thermostat 22.
Is attached. Further, a washing pipe 23 is connected to the heating unit 20, and the washing pipe 23 is connected to the switching valve 11. Then, by switching the switching valve 11, one of the water supply pipe 12 and the cleaning pipe 23 is connected to the water supply pipe 10. Further, the heating unit 20
Is connected to a drain pipe 24. The drain pipe 24 is connected to a drain pipe 26 via a water stop valve 25 operated by the control circuit 6, and the tip of the drain pipe 26 is connected to a drain port. 27
It has become. And these drain pipes 24 and drain pipes
26 forms a drainage channel 28. 29 is a drainage tank.

Next, based on the flowchart of FIG.
The operation of this embodiment will be described. In the initial state, the control circuit 6
The switching valve 7 is switched so that the water supply pipe 5 and the water supply pipe 8 communicate with each other, and the water supply pipe 10 and the water supply pipe
The switching valve 11 is switched so that 12 communicates, and the entire water supply path 18 from the discharge port 4 to the water supply port 17 through the hollow fiber membrane module 9 is in communication. Then, in step S1, when the drinking water W is put into the water storage tank 1 up to the level of the water level line 2, the process proceeds to step S2, where the initial state described above is continued, and the water level of the drinking water W and the hollow fiber membrane module 9 Water W is generated by the hollow fiber membrane module 9 due to the water pressure caused by the difference in height of the hollow fiber membrane module 9.
, And the pump vortex chamber 14 is provided at a position lower than the water level line 2, so that the inside of the pump vortex chamber 14 is filled with the drinking water W that has passed through the hollow fiber membrane module 9. In this state, when the electric motor 13 is operated to drive the water supply pump 15, the water purification step is started. When the water supply pump 15 is driven, suction pressure is applied to the drinking water W, so that the drinking water W is supplied through the water supply pipe 5, the switching valve 7, and the water supply pipe 8, as shown by the solid arrow in FIG. 9, where fine solids, bacteria and the like are filtered. Then, the filtered drinking water W is sucked into the water supply pump 15 through the water supply pipe 10, the switching valve 11, and the water supply pipe 12, and is supplied to the outside from the water supply port 17 through the water supply pipe 16.

On the other hand, in step S1, when the water level of the drinking water W in the water storage tank 1 drops and becomes lower than the position of the water level sensor 3, the control circuit 6 starts controlling the cleaning process. First, in step S3, the water level sensor 3 detects a drop in the water level and sends a signal to the control circuit 6. Based on this signal, the control circuit 6 stops energizing the motor 13 and turns on the water supply pump 15. Stop. Next, in step S4, the switching valve 7 is switched by the control circuit 6 so that the water supply pipe 8 communicates with the water supply pipe 19, and the water supply pipe 8, the hollow fiber membrane module 9, the water supply pipe 10, the switching valve 11, the drinking water W remaining in the water supply pipe 12, the pump vortex chamber 14, and the water supply pipe 16
Is discharged. Further, the process proceeds to step S5, where the switching valve 7 is switched by the control circuit 6 so that the water supply pipe 5 and the water supply pipe 19 communicate with each other, and the washing pipe 23 and the water supply pipe are connected.
The switching valve 11 is switched so as to communicate with the
An appropriate amount of drinking water W is stored in 20. After an appropriate amount of drinking water W is stored in the heating unit 20 (step S6), the control circuit 6
As a result, the switching valves 7 are all closed and the heater 21 is energized (step S7), and the drinking water W in the heating unit 20 is heated. When the drinking water W is heated, the pressure in the heating section 20 rises, whereby the heated drinking water W rises up the washing pipe 23 as shown by the dashed arrow in FIG. The tube 10 leads to the hollow fiber membrane module 9. The heated drinking water W passes through the hollow fiber membrane module 9 due to the pressure generated in the heating unit 20 due to the heating and the pressure due to the water level difference between the switching valve 11 and the hollow fiber membrane module 9. The bacteria remaining in the inside are sterilized by heat. At this time, since the switching valve 7 is closed, the heated drinking water W is stored in the water supply pipe 8, the hollow fiber membrane module 9, and the water supply pipe 10. When a predetermined amount of the drinking water W is stored and the amount of water in the heating unit 20 becomes equal to or less than a predetermined value (step S8), the control circuit 6 switches the switching valve 7 to the water supply pipe 8.
And the water pipe 19 are switched to communicate with each other (step S9), and the water supply pipe 8, the switching valve 7, and the water pipe together with the dead bacteria of the sterilized drinking water W that has passed through the hollow fiber membrane module 9.
After passing through 19, it is discharged to the heating unit 20. This is step S
After being repeated several times by 10, energization of the heater 21 is stopped, and the water stop valve 25 is opened by the control circuit 6 in the procedure of step S 11, and the drain pipe 24 and the drain pipe 26 are communicated, and the drinking water is discharged. W is discharged from the drain port 27 to the drain tank 29. Thus, the cleaning process of steps S3 to S11 is completed. After the completion of the cleaning step, the switching valve 7 and the switching valve 11 are returned to the initial state by the control circuit 6.

Next, another embodiment of the present invention will be described with reference to FIG. Note that the same reference numerals are given to portions common to the above-described embodiment, and description thereof will be omitted. A heating unit 32 is connected to the switching valve 7 via a water pipe 31. A heater 33 as a heating means and a thermostat 34 are attached to the heating section 32.
Further, a washing tube 35 is connected to the heating unit 32,
This washing pipe 35 is connected to the switching valve 11. Also,
A drain pipe 36 serving as a drain passage is connected to the switching valve 7, and a distal end thereof serves as a drain port 37. Reference numeral 38 denotes a drain tank.

Next, based on the flowchart of FIG.
The operation of this embodiment will be described. In addition, the water purification process of step S21 and step S22 of FIG. 4 is the same operation as step S1 and step S2 of the above embodiment, and the description thereof will be omitted. In step S21,
When the water level of the drinking water W in the water storage tank 1 decreases and becomes lower than the position of the water level sensor 3, the control circuit 6 starts controlling the cleaning process. First, the water level sensor 3 detects a drop in the water level and sends a signal to the control circuit 6. Based on this signal, the control circuit 6 stops energizing the motor 13 and stops the water supply pump 15 (step S23). Next, the switching valve 7 is switched by the control circuit 6 so that the water supply pipe 8 and the water flow pipe 31 communicate with each other, and the water supply pipe 8, the hollow fiber membrane module 9, the water supply pipe 10,
Drinking water W remaining in the switching valve 11, the water supply pipe 12, the pump vortex chamber 14, and the water supply pipe 16 is discharged to the heating unit 32 through the water flow pipe 31 (Step S24). Further, the next step S2
At 5, the switching circuit 7 is switched by the control circuit 6 so that the water supply pipe 5 and the water pipe 31 communicate with each other, and the water supply pipe 10
The switching valve 11 is switched so that the washing pipe 35 communicates with the washing pipe 35, and an appropriate amount of the drinking water W is stored in the heating unit 32. In step S26, after an appropriate amount of drinking water W is stored in the heating unit 32, the switching valve 7 is switched by the control circuit 6 so that the water supply pipe 8 and the drain pipe 36 communicate with each other.
Is turned on (step S27), and the drinking water W in the heating unit 32 is turned on.
Is heated. When the drinking water W is heated, the pressure in the heating section 32 rises, whereby the heated drinking water W rises up the washing pipe 35 as shown by the dashed arrow in FIG.
And the water supply pipe 10 to the hollow fiber membrane module 9. The heated drinking water W passes through the hollow fiber membrane module 9 due to the pressure generated in the heating unit 32 by the heating and the pressure due to the water level difference between the switching valve 11 and the hollow fiber membrane module 9,
Germs remaining in the hollow fiber membrane module 9 are sterilized by heat. The drinking water W that has passed through the hollow fiber membrane module 9 passes through the water supply pipe 8, the switching valve 7, and the drain pipe 36, and is discharged from the drain port 37 to the drain tank 38. Then, in the next step S28, when the amount of the drinking water W in the heating unit 32 decreases, the temperature of the heating unit 32 rises and the thermostat increases.
34 operates, the power supply to the heater 33 is cut off, and step S2 is performed.
The washing process from Step 3 to Step S29 ends. After the completion of the cleaning step, the switching valve 7 and the switching valve 11 are returned to the initial state by the control circuit 6.

Next, still another embodiment of the present invention will be described with reference to FIG. Note that the same reference numerals are given to portions common to the above-described embodiment, and description thereof will be omitted. A heating unit 42 is connected to the switching valve 7 via a cleaning pipe 41 which also serves as a water pipe. The heater 43 includes a heater 43 as a heating means and a thermostat 44.
Is attached. Further, a drain pipe 45 as a drain passage is connected to the switching valve 11, and a distal end thereof serves as a drain port. 47 is a drainage tank.

Next, based on the flowchart of FIG.
The operation of this embodiment will be described. In addition, the water purification process of step S31 and step S32 in FIG. 6 is the same operation as step S1 and step S2 of the above-described embodiment, and thus the description thereof is omitted. When the water level of the drinking water W in the water storage tank 1 decreases and becomes lower than the position of the water level sensor 3, the control circuit 6 starts controlling the cleaning process. First, the water level sensor 3 detects a drop in the water level and sends a signal to the control circuit 6,
Based on this signal, the control circuit 6 stops supplying power to the motor 13 and stops the water supply pump 15 (step S33).
Next, the switching valve 7 is switched by the control circuit 6 so that the water supply pipe 8 and the washing pipe 41 communicate with each other, and the water supply pipe 8, hollow fiber membrane module 9, water supply pipe 10, switching valve 11, water supply pipe 12, pump Drinking water W remaining in the vortex chamber 14 and the water supply pipe 16 is heated
It is discharged to 42 (step S34). Further, in the next step S35, the water supply pipe 5 and the cleaning pipe 41 are controlled by the control circuit 6.
And the switching valve 7 is switched so that
The switching valve 11 is switched so that the water supply pipe 10 and the drain pipe 45 communicate with each other, and an appropriate amount of the drinking water W is stored in the heating unit 42. In step S36, after an appropriate amount of drinking water W is stored in the heating unit 42, the control circuit 6 controls the water supply pipe 8 and the washing pipe 41.
The switching valve 7 is switched so that is communicated, and the heater 43 is energized (step S37), and the drinking water W in the heating unit 42 is heated. When the drinking water W is heated, the heating unit 42
As a result, the heated drinking water W rises in the washing pipe 41 and reaches the hollow fiber membrane module 9 via the switching valve 7 and the water supply pipe 8 as shown by the broken arrow in FIG. . The heated drinking water W passes through the hollow fiber membrane module 9 by the pressure generated in the heating unit 42 by the heating,
Germs remaining in the hollow fiber membrane module 9 are sterilized by heat. The drinking water W that has passed through the hollow fiber membrane module 9 passes through the water supply pipe 10, the switching valve 11, and the drain pipe 45, and is discharged from the drain port 46 to the drain tank 47. Then, in the next step S38, when the amount of drinking water W in the heating unit 42 decreases, the temperature of the heating unit 42 rises and the thermostat
44 operates, the power supply to the heater 43 is cut off, and step S3
The washing process from Step 3 to Step S39 ends. After the completion of the cleaning step, the switching valve 7 and the switching valve 11 are returned to the initial state by the control circuit 6.

As described above, according to the present embodiment, the water tank 1
A discharge port 4 provided in the water storage tank 1;
A water supply port 17 provided outside, a water supply path 18 connecting the discharge port 4 and the water supply port 17, and a water supply pump provided in the middle of the water supply path 18
In the water purification device having the hollow fiber membrane module 9 and the hollow fiber membrane module 9, the hollow fiber membrane module 9 is formed of a resin having heat resistance, and the heating units 20, 32, and 42 connected to the water storage tank 1 and the water supply passage 18 are provided. The heaters 21, 33, 43 for heating the water in the sections 20, 32, 42 are connected to the water supply path 18 via the switching valves 7, 11, and the heating sections 20, 32, 42 are heated to the water supply path 18. Washing pipes 23, 35, 41 as washing paths for sending water, and drain pipes connected to water supply paths 18 via switching valves 7, 11 for discharging hot water passing through the hollow fiber membrane module 9 to the outside. 24, 26, 3
6, 45.

With the above configuration, in the water purification step, the water storage tank 1, the hollow fiber membrane module 9 and the water supply port 17 are connected to the water supply passage.
By communicating with 18 and driving the water supply pump 15,
The water in the water storage tank 1 is filtered by the hollow fiber membrane module 9 to purify the water, and supplied through the water supply port 17. In the cleaning step, water is stored in the heating unit 20 and the water is stored in the heaters 21 and 3.
Heat is generated at 3 and 43 to make hot water, and the hot water is passed through the hollow fiber membrane module 9 and the water supply passage 18 to sterilize the inside of the hollow fiber membrane module 9 and the water supply passage 18. The hot water that has passed through the hollow fiber membrane module 9 is discharged to the outside through drainage pipes 24, 26, 36, and 45. This makes it possible to keep the inside of the hollow fiber membrane module 9 and the water supply passage 18 sanitary.

In addition, in this embodiment, a control circuit 6 for controlling the switching valves 7, 11 and the heaters 21, 33, 43 is provided in addition to the above configuration, and the water level sensor 3 is provided in the water storage tank 1. The control circuit 6 performs water purification by the hollow fiber membrane module 9 while the water level sensor 3 detects a water level higher than a predetermined value. When the water level sensor 3 detects a water level lower than a predetermined value, the hollow fiber membrane It operates to wash the module 9 with hot water.

In this case, when the water level in the water storage tank 1 is equal to or higher than a predetermined value, water is purified by the hollow fiber membrane module 9. When the water level in the water storage tank 1 is equal to or lower than the predetermined value, the hollow fiber membrane module is used. 9 is washed with hot water. As a result, the inside of the hollow fiber membrane module 9 and the water supply channel 18 can be periodically cleaned, and the hollow fiber membrane module 9 can be cleaned.
And the inside of the water supply channel 18 can be kept more sanitary.

In addition, as an effect of each embodiment, in the embodiments shown in FIGS.
20 is connected between both ends of the hollow fiber membrane module 9 and the heating section 2
A circulation path capable of circulating hot water a plurality of times is formed by the water supply path 18 including the cleaning path 23, the washing path 23, and the hollow fiber membrane module 9. Thereby, the hot water heated by the heating unit 20 can be circulated through the hollow fiber membrane module 9 a plurality of times.
The inside of the hollow fiber membrane module 9 and the water supply path 18 can be effectively washed while preventing use of useless water. Also,
Since the configuration is such that hot water is circulated by increasing the pressure of the water heated in the heating section 20, no pressure feeding means is required and the structure is simplified. This is also true for each of the other embodiments in which hot water is sent to the hollow fiber membrane module 9 using the pressure increase of the water heated in the heating unit 20.

In the embodiment shown in FIGS. 5 and 6,
A water pipe for sending water to the heating unit 42 is common to the washing path 41 for sending hot water to the hollow fiber membrane module 9. In this case, by sharing the pipe, the inside of the hollow fiber membrane module 9 and the water supply path 18 can be kept hygienic with a simple configuration.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made within the gist of the invention. For example, in each of the above embodiments, the heated drinking water is pumped up by the pressure increase in the heating unit and passed through the hollow fiber membrane module.For example, a pump is provided in a washing pipe or the like, and the heated drinking water is supplied to the pump. The water may be pumped. In each of the above embodiments, the solenoid valve is used as the switching valve. However, the present invention is not limited to this, and various other switching mechanisms can be used. Further, in this embodiment, the switching valve is automatically switched using the control circuit, but the switching of the switching valve may be performed manually. Further, in this embodiment, the operation of the control circuit is based on the signal from the water level sensor, but this is done, for example, by measuring the total flow rate of the drinking water flowing through the hollow fiber membrane module, and controlling based on this measured value. The circuit may be operated.

[0023]

According to a first aspect of the present invention, there is provided a water purification apparatus, comprising: a water storage tank, a discharge port provided in the water storage tank, and a water supply provided outside the water storage tank. Mouth and
In a water purification device having a water supply channel connecting the discharge port and the water supply port, and a water supply pump and a hollow fiber membrane module provided in the middle of the water supply channel, the hollow fiber membrane module is formed of a resin having heat resistance. A heating unit connected to the water storage tank and the water supply passage, a heater for heating water in the heating unit, and water connected to the water supply passage via a switching valve and heated from the heating unit to the water supply passage. And a drainage path connected to the water supply path via a switching valve to discharge hot water passing through the hollow fiber membrane module to the outside. Can be kept hygienic.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, a control circuit for controlling the switching valve and the heater is provided, and a water level sensor is provided in the water storage tank. Along with performing the water purification by the hollow fiber membrane module while the control circuit detects the water level equal to or higher than a predetermined value, the hollow circuit is used when the water level sensor detects the water level equal to or lower than a predetermined value. It operates to wash the fiber membrane module with hot water, so that the inside of the hollow fiber membrane module and the water supply path can be periodically cleaned, and the inside of the hollow fiber membrane module and the water supply path is kept more sanitary. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of one embodiment of the present invention.

FIG. 3 is a schematic diagram showing another embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of another embodiment of the present invention.

FIG. 5 is a schematic diagram showing still another embodiment of the present invention.

FIG. 6 is a flowchart showing the operation of still another embodiment of the present invention.

[Description of Signs] 1 water storage tank 3 water level sensor 4 discharge port 6 control circuit 7,11 switching valve 9 hollow fiber membrane module 15 water supply pump 17 water supply port 18 water supply path 20,32,42 heating section 21,33,43 heater 23 , 35,41 Wash pipe (wash channel) 24,26,36,45 Drain pipe (drain channel) 28 Drain channel

Claims (2)

[Claims] 1. A water storage tank, a discharge port provided in the water storage tank, a water supply port provided outside the water storage tank, a water supply channel connecting the discharge port and the water supply port, In a water purification device having a water supply pump and a hollow fiber membrane module provided in the middle, the hollow fiber membrane module is formed of a heat-resistant resin, and a heating unit connected to the water storage tank and the water supply path; A heater for heating water in the unit,
A washing path connected to the water supply path via a switching valve, for sending heated water from the heating unit to the water supply path, and connected to the water supply path via a switching valve, and passed through the hollow fiber membrane module. A water purification device comprising a drainage channel for discharging hot water to the outside. 2. A control circuit for controlling the switching valve and the heater, a water level sensor provided in the water storage tank, and the control circuit detects a water level equal to or higher than a predetermined value. The method according to claim 1, wherein the hollow fiber membrane module performs water purification, and operates so as to wash the hollow fiber membrane module with hot water when the water level sensor detects a water level equal to or lower than a predetermined value. Cleaning equipment.