JP2023032884A - Purified water supply system - Google Patents

Abstract

To provide a purified water supply system capable of saving space and reducing cost, and maintaining water to be treated in a water supply line in an appropriate state even when the supply of purified water to a purified water tank is stopped.SOLUTION: A raw water tank 10, a reverse osmosis membrane device 20, an ion exchange device 30, an ultrafiltration device 40, and a purified water tank 50 are connected in series by a water delivery line 60. The system consists of a return line 90 that branches off from water delivery line 60e downstream from the ultrafiltration device 40 and returns purified water that has passed through the ultrafiltration device 40 back upstream from the ultrafiltration device 40.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a purified water supply system that produces purified water by removing impurities from raw water and supplies the purified water to a point of use.

Conventionally, there is known a purified water supply system that produces purified water such as pure water from raw water and supplies the purified water to a point of use. Purified water supply systems have various configurations, and include a reverse osmosis membrane device having a reverse osmosis membrane, an ion exchange device having an ion exchange resin, and an ultrafiltration device having an ultrafiltration membrane. There is a known one (see, for example, Patent Literature 1).

Patent Document 1 includes a raw water tank, an RO device that is a reverse osmosis membrane device, an ion exchange device that is a so-called ion exchange resin tower, an ultrafiltration device, and a storage tank, and various equipment including these are connected in series by piping.

By configuring such various devices to be connected in series by pipes, it is possible to save the space of the purified water supply system and to reduce the installation cost.

Japanese Patent Application Laid-Open No. 2020-69429

However, in the above configuration, for example, when the amount of purified water used at the point of use decreases or becomes zero due to failure or maintenance of the point of use, the upstream of the storage tank (purified water tank) There is a possibility that the water to be treated (including permeated water and purified water) in the pipe (water supply line) cannot be maintained in good condition.

More specifically, when the amount of purified water used at the point of use decreases or becomes zero due to failure of the point of use, etc., the supply of purified water that has passed through the ultrafiltration device to the purified water tank is temporarily stopped accordingly. Sometimes. At that time, the water to be treated remains in the water supply line on the upstream side of the purified water tank.

While the water to be treated remains in the water supply line, general bacteria may grow or proliferate in the water to be treated, making it impossible to maintain the water to be treated in an appropriate condition. Therefore, when the supply of purified water to the purified water tank is stopped for a relatively long period of time, it is necessary to discharge all the water to be treated in the water supply line when restarting the supply of purified water. It may be necessary to perform line cleaning.

As a result, there arise problems such as the time required to restart the supply of purified water, and the increase in cost associated with the discharge of the water to be treated and the cleaning of the water supply line.

The present invention has been made in view of such circumstances, and is capable of saving space and reducing costs, and furthermore, even when the supply of purified water to the purified water tank is stopped, the water supply line will be damaged. An object of the present invention is to provide a purified water supply system capable of maintaining treated water in an appropriate state.

One aspect of the present invention for achieving the above object is a raw water tank in which raw water is stored, a reverse osmosis membrane device arranged downstream of the raw water tank, and a reverse osmosis membrane device arranged downstream of the reverse osmosis membrane device. an ion exchange device, an ultrafiltration device arranged downstream of the ion exchange device, and a purified water tank in which purified water that has passed through the ultrafiltration device is stored, and from the purified water tank A purified water supply system for supplying purified water to a point of use, wherein the raw water tank, the reverse osmosis membrane device, the ion exchange device, the ultrafiltration device, and the purified water tank are connected to a water supply line is connected in series with the ultrafilter, and is provided branching from the water supply line on the downstream side of the ultrafilter, and returns purified water that has passed through the ultrafilter to the upstream side of the ultrafilter A purified water supply system characterized by having a return line.

According to the present invention, it is possible to save space and reduce costs, and even when the supply of purified water to the purified water tank is stopped, the water to be treated containing purified water in the water supply line is kept in an appropriate state. It is possible to provide a purified water supply system that can be maintained at

1 is a schematic configuration diagram of a purified water supply system according to one embodiment of the present invention; FIG. It is a schematic block diagram which shows the modification of the purified water supply system which concerns on one Embodiment of this invention. 4 is a graph showing the relationship between the voltage applied to the electrodeionization apparatus and the purity of deionized water. 4 is a graph showing the relationship between the voltage applied to the electrodeionization apparatus and the purity of deionized water.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a purified water supply system according to one embodiment of the present invention.
The purified water supply system 1 of the present embodiment includes a raw water tank 10, a reverse osmosis membrane device (RO device) 20, an electrodeionization device (EDI device) 30 as an ion exchange device, and an ultrafiltration device 40. , and a purified water tank 50 . The constructions of the raw water tank 10, the reverse osmosis membrane device 20, the electrodeionization device 30, the ultrafiltration device 40, and the purified water tank 50 are known, and will be briefly described.

The raw water tank 10 is a tank in which raw water, which is a raw material of purified water, is temporarily stored. As raw water, ordinary water such as tap water is used, for example. The capacity of the raw water tank 10 is not particularly limited, but in this embodiment, a tank with a capacity of about 500L is used.

The reverse osmosis membrane device 20 is arranged downstream of the raw water tank 10 . The reverse osmosis membrane device 20 has a reverse osmosis membrane (RO membrane), and the raw water (water to be treated) sent from the raw water tank 10 is divided into concentrated water containing impurities and permeated water from which impurities have been removed by the reverse osmosis membrane. and separate. The permeated water separated by the reverse osmosis membrane device 20 is passed through the downstream side electrodeionization device 30, and the concentrated water is not passed through the electrodeionization device 30 and is discharged outside the reverse osmosis membrane device 20. Ejected.

The electrodeionization device 30 is an example of an ion exchange device and is arranged downstream of the reverse osmosis membrane device 20 . The electrodeionization device (EDI device) 30 deionizes (demineralizes) the permeated water (water to be treated) that has passed through the reverse osmosis membrane device 20, and simultaneously performs regeneration of the ion exchange resin. The electrodeionization apparatus 30 obtains deionized water (water to be treated) by removing ions (cations and anions) from the permeated water. This deionized water (water to be treated) is passed to the downstream ultrafiltration device 40 . The cations and anions removed by the electrodeionization device 30 are discharged outside the electrodeionization device 30 as concentrated water.

The amount of ions (cations and anions) removed by the electrodeionization apparatus 30, which will be described later in detail, varies depending on the applied voltage (applied voltage), but also varies depending on the flow rate of the permeated water (water flow rate). do. For this reason, in the present embodiment, the voltage applied to the electrodeionization device 30 is appropriately changed according to the amount of permeated water. Thereby, the ions contained in the permeated water can be appropriately removed by the electrodeionization device 30 .

The ultrafiltration device 40 is arranged downstream of the electrodeionization device 30 . The ultrafiltration device 40 has an ultrafiltration membrane, and the deionized water (water to be treated) that has been treated by the electrodeionization device 30 is passed through the ultrafiltration membrane. Remove particles that may be By filtering the deionized water in the ultrafiltration device 40 in this manner, purified water (pure water) having a desired level of purity required for pharmaceutical solutions, for example, is obtained.

The purified water tank 50 is arranged downstream of the ultrafilter 40 and temporarily stores the purified water that has passed through the ultrafilter 40 . The capacity of the purified water tank 50 is not particularly limited, but in this embodiment, a capacity of about 100 L is used.

The raw water tank 10, the reverse osmosis membrane device 20, the electrodeionization device 30, the ultrafiltration device 40, and the purified water tank 50 are connected to water supply pipes 60 (60a, 60b, 60c, 60d, 60e), which are water supply lines. are connected in series by

That is, the raw water tank 10, the reverse osmosis membrane device 20, the electrodeionization device 30, the ultrafiltration device 40, and the purified water tank 50 are connected in this order without a storage tank interposed therebetween. 60 are serially connected. The storage tank referred to here temporarily stores the permeated water (to-be-treated water) treated by the reverse osmosis membrane device 20 or the deionized water (to-be-treated water) treated by the electrodeionization device 30. It is a tank for storage.

Since each component of the purified water supply system 1 is connected in series by the water supply pipe 60 in this way, space can be saved, and the installation cost can be reduced.

A water pump 70 is provided between the raw water tank 10 and the reverse osmosis membrane device 20 . The raw water (water to be treated) in the raw water tank 10 is fed to the reverse osmosis membrane device 20 through the water pipe 60 at a predetermined water pressure by the water pump 70 . Furthermore, the permeated water that has passed through the reverse osmosis membrane is passed through the electrodeionization device 30 and the ultrafiltration device 40 and the purified water is supplied to the purified water tank 50 .

The purified water tank 50 is also connected to the point of use UP by a supply line (supply pipe) 80 . That is, the purified water stored in the purified water tank 50 is supplied to the point of use UP via the supply pipe 80 . A point of use UP is a facility, an apparatus, a place, or the like, where purified water is used.

The configuration of the supply pipe 80 is not particularly limited, but in this embodiment, the configuration includes a first circulation pipe 81 and a second circulation pipe 82 . The first circulation pipe 81 is a pipe for supplying the purified water stored in the purified water tank 50 to the point of use UP. On the other hand, the second circulation pipe 82 is a pipe for returning purified water not used at the point of use UP to the purified water tank 50 .

A supply pump 83 is provided in the first circulation pipe 81 . Purified water in the purified water tank 50 is supplied to the point of use UP via the first circulation pipe 81 by the supply pump 83, and purified water not used at the point of use UP is supplied to the second circulation pipe 82. It returns to the purified water tank 50 via.

A first discharge pipe 84 is connected to the first circulation pipe 81 , and a second discharge pipe 85 is connected to the second circulation pipe 82 . These first discharge pipe 84 and second discharge pipe 85 are pipes for discharging, for example, the cleaning liquid used for cleaning the inside of the supply pipe 80 and the steam used for sterilization to the outside.

Although not shown, the supply pipe 80 and the first discharge pipe 84 and the second discharge pipe 85 are provided with a plurality of valves for controlling the flow of purified water or the like. By controlling the opening and closing states of these valves, the supply of purified water from the supply pipe 80 to the use point UP and the discharge of the cleaning solution from the first discharge pipe 84 and the second discharge pipe 85 are appropriately controlled. Execute.

Furthermore, the purified water supply system 1 according to the present invention having such a configuration has a return pipe 90 as a return line.

The return pipe 90 is provided by branching from the water supply pipe 60e downstream of the ultrafilter 40, and is used to return the purified water that has passed through the ultrafilter 40 to the upstream side of the ultrafilter 40. Plumbing.

In this embodiment, the return pipe 90 is branched from the water supply pipe 60 e and connected to the raw water tank 10 . That is, the return pipe 90 has one end connected to the water supply pipe 60 e and the other end connected to the raw water tank 10 . The return pipe 90 is provided with a first valve 61 in the vicinity of the connection with the water supply pipe 60e. A second valve 62 is provided on the downstream side of the connecting portion of the water supply pipe 60 e with the return pipe 90 . These first valve 61 and second valve 62 are composed of electromagnetic valves that can be switched to either a fully open or fully closed state, control valves that can adjust the degree of opening, or the like.

The purified water supply system 1 according to the present invention is provided with such a return pipe 90, so that the purified water and the water to be treated in the water supply pipe 60 can be maintained in an appropriate state. For example, even if the amount of purified water used decreases or becomes zero due to failure or maintenance of the point of use UP and the supply of purified water to the purified water tank 50 is stopped, the purified water in the water supply pipe 60e is returned through the return pipe 90. can be returned to the raw water tank 10. As a result, it is possible to prevent the purified water and the water to be treated from accumulating in the water pipe 60 , thereby suppressing the breeding or multiplication of general bacteria in the purified water and the water to be treated in the water pipe 60 . Therefore, even while the supply of purified water to the purified water tank 50 is stopped, the purified water and the water to be treated in the water supply pipe 60 can be maintained in an appropriate state.

The return pipe 90 may be provided so as to return the purified water to the upstream side of the ultrafiltration device 40. For example, as shown in FIG. may be connected to

However, it is preferable that the return pipe 90 is connected to the raw water tank 10 as in the present embodiment. That is, when the supply of purified water to the purified water tank 50 is stopped, it is preferable to return the purified water in the water supply pipe 60e to the relatively large-capacity raw water tank 10 via the return pipe 90. As a result, for example, even when the temperature of the purified water in the water supply pipe 60e rises to a relatively high temperature, it is possible to suppress the adverse effects caused by this. Furthermore, even if air bubbles are mixed in the purified water in the water supply pipe 60e, there is an effect that the air bubbles can be removed by returning the purified water to the raw water tank 10. FIG.

Hereinafter, a purified water supply process executed in the purified water supply system 1 according to the present embodiment, in particular, a purified water supply process to the purified water tank 50 will be described.

As shown in FIG. 1, the purified water supply system 1 according to this embodiment includes a control device 100 that comprehensively controls various devices. The control device 100 includes at least supply amount adjustment means 101 and voltage control means 102 .

The supply amount adjusting means 101 adjusts the amount of purified water supplied to the purified water tank 50 according to the amount of purified water used at the point of use UP. As described above, the purified water tank 50 and the point of use UP are connected by the supply pipe 80 including the first circulation pipe 81 and the second circulation pipe 82 . Therefore, the amount of purified water in the purified water tank 50 also fluctuates as the amount of purified water used at the point of use UP changes.

The purified water tank 50 is provided with various sensors for detecting the amount of purified water stored therein. For example, a liquid level sensor 110 is provided to detect the liquid level of the purified water stored in the purified water tank 50 .

The supply amount adjusting means 101 appropriately changes the output of the water pump 70 and the opening/closing state of the second valve 62 based on the detection result of the liquid level sensor 110, thereby supplying the purified water to the purified water tank 50. Adjust quantity. For example, when the amount of purified water in the purified water tank 50 reaches a preset threshold value A1, the supply amount adjusting means 101 gradually reduces the output of the water pump 70 . That is, the amount of purified water supplied to the purified water tank 50 is gradually decreased. However, the water pump 70 is not stopped, and when the preset minimum output is reached, the output is maintained.

Here, when purified water is supplied to the purified water tank 50, the first valve 61 is in a closed state (closed state) and the second valve 62 is in an open state (open state). .

The supply amount adjusting means 101 opens the first valve 61 and closes the second valve 62 when the amount of purified water in the purified water tank 50 reaches a threshold A2 larger than the threshold A1. do. As a result, the amount of purified water supplied to the purified water tank 50 becomes zero.

However, the production of purified water itself is not stopped, and the purified water that has passed through the ultrafiltration device 40 is returned to the raw water tank 10 via the return pipe 90 . That is, the purified water and the water to be treated in the water supply pipe 60 circulate through the return pipe 90 without stagnation in the water supply pipe 60 .

After that, when the amount of purified water in the purified water tank 50 decreases to a threshold A3 which is smaller than the threshold A1, the supply amount adjusting means 101 closes the first valve 61 and opens the second valve 62. Then, the output of the water pump 70 is appropriately adjusted, and the supply of purified water to the purified water tank 50 is resumed.

As described above, the purified water supply system 1 according to the present embodiment continues to produce purified water and passes through the ultrafiltration device 40 even when the supply of purified water to the purified water tank 50 is stopped. Purified water is returned to the raw water tank 10 via a return pipe 90. - 特許庁Therefore, the purified water and the water to be treated in the water supply pipe 60 can be maintained in an appropriate state.

Therefore, the supply of purified water to the purified water tank 50 can be restarted by controlling the opening/closing states of the first valve 61 and the second valve 62 and by adjusting the output of the water pump 70 as necessary. can be done in a relatively short time.

In the conventional purified water supply system, which does not have a return pipe, when restarting the supply of purified water to the purified water tank, the purified water in the water supply pipe and the water to be treated are discharged (discarded), and the inside of the water supply pipe is washed. or sterilization may be required. However, since the purified water supply system 1 of the present invention does not require such processing, the time required for resuming supply can be shortened, and the running cost can be reduced accordingly.

Also, the voltage control means 102 provided in the control device 100 controls the voltage (applied voltage) applied to the electrodeionization device 30 .

As described above, in the present embodiment, the supply amount adjusting means 101 changes the output of the water pump 70 to adjust the amount of purified water supplied to the purified water tank 50 . At that time, the amount of permeated water passing through the electrodeionization apparatus 30 also fluctuates according to the output of the water pump 70 .

The voltage control means 102 changes the voltage applied to the electrodeionization device 30 in accordance with such fluctuations in the amount of permeated water passing through the electrodeionization device 30 . More specifically, the voltage control means 102 controls the applied voltage to decrease as the amount of permeated water passing through the electrodeionization device 30 decreases.

The method for detecting the amount of permeated water passing through the electrodeionization apparatus 30 is not particularly limited. is estimated from the output of That is, the voltage control means 102 appropriately controls the voltage applied to the electrodeionization device 30 according to the output of the water pump 70 changed by the supply amount adjustment means 101 .

By changing the voltage applied to the electrodeionization device 30 in accordance with the amount of permeated water passing through the electrodeionization device 30 in this manner, the permeate passes through the electrodeionization device 30 as described below. The purity of deionized water (water to be treated) can be appropriately increased.

FIG. 3 is a diagram showing the relationship between the purity of deionized water with a water temperature of about 11° C. and the voltage applied to the electrodeionization apparatus, and FIG. It is a figure which shows the relationship with the applied voltage of a type|formula deionization apparatus.

As shown in FIGS. 3 and 4, the purity of the deionized water that has passed through the electrodeionization apparatus 30 varies with the applied voltage of the electrodeionization apparatus 30, although the method of fluctuation varies depending on the temperature and flow rate of the permeated water. Varies depending on For this reason, it is preferable that the voltage applied to the electrodeionization device 30 is appropriately set according to the temperature and amount of permeated water that is passed through the electrodeionization device 30 .

For example, when the temperature of the permeated water passing through the electrodeionization device 30 is about 11° C. and the water flow rate is the first water flow rate L1, as indicated by the solid line in FIG. The purity becomes the highest value P1 when the applied voltage is the first voltage V1. Therefore, in this case, the applied voltage is preferably set to about the first voltage V1. This facilitates increasing the purity of the deionized water that has passed through the electrodeionization device 30 .

Further, for example, when the temperature of the permeated water that is passed through the electrodeionization device 30 is about 25° C. and the water flow rate is the first water flow rate L1, deionization occurs as indicated by the solid line in FIG. The purity of water becomes the highest value P2 at the second voltage V2 or higher. Therefore, in this case, the applied voltage is preferably set to the second voltage V2 or higher. This makes it easier to increase the purity of the deionized water that has passed through the electrodeionization device 30 . In particular, it is preferable that the applied voltage is set to about the second voltage V2. As a result, the purity of the deionized water that has passed through the electrodeionization device 30 can be more easily increased, and power consumption can be suppressed.

Furthermore, as indicated by the dotted line in FIG. 3, the temperature of the permeated water that is passed through the electrodeionization device 30 is about 11° C., and the second water flow rate L2 is lower than the first water flow rate L1. , the purity of deionized water becomes the highest value P1 when the applied voltage is the third voltage V3. That is, in this case, the manner in which the purity of deionized water fluctuates with an increase in the applied voltage is the same as in the case where the water flow rate shown by the solid line in FIG. It shifts to the lower voltage side than in the case of L1. Therefore, in this case, the applied voltage is preferably set to about the third voltage V3, which is lower than the first voltage V1. This makes it easier to increase the purity of the deionized water that has passed through the electrodeionization device 30 .

Further, as indicated by the dotted line in FIG. 4, the temperature of the permeated water that is passed through the electrodeionization apparatus 30 is about 25° C., and the second water flow rate L2, which is less than the first water flow rate L1, is used. In some cases, the purity of deionized water reaches the highest value P2 when the applied voltage is the fourth voltage V4. That is, in this case, the manner in which the purity of deionized water fluctuates with an increase in the applied voltage is the same as in the case where the water flow rate shown by the solid line in FIG. 4 is the first water flow rate L1. It shifts to the lower voltage side than in the case of L1. Therefore, in this case, the applied voltage is preferably set to about the fourth voltage V4, which is lower than the second voltage V2. This makes it easier to increase the purity of the deionized water that has passed through the electrodeionization device 30 .

As described above, the amount of ions removed by the electrodeionization apparatus 30 varies depending on the applied voltage and the amount of permeated water. That is, the purity of the deionized water that has passed through the electrodeionization apparatus 30 varies depending on the applied voltage and the amount of permeated water that passes through.

Therefore, by appropriately changing the voltage applied to the electrodeionization device 30 according to the amount of permeated water passing through the electrodeionization device 30 as described above, more specifically, By setting the applied voltage to be lower as the permeated water flow rate is lower, the purity of deionized water can be easily increased.

Although one embodiment of the present invention has been described above, the present invention is, of course, not limited to the above-described embodiments. and other modifications are possible.

For example, in the above embodiment, the output of the water pump 70 is controlled to adjust the amount of purified water supplied to the purified water tank 50, but the method of adjusting the amount of supply is not limited to this. For example, the output of the water pump 70 may be kept constant, and the opening of the first valve 61 may be controlled to change the flow rate of purified water returned from the return pipe 90 to the raw water tank 10 . Even with this method, the amount of purified water supplied to the purified water tank 50 can be adjusted.

Further, in the above-described embodiment, the configuration including the return pipe 90 branched from the water supply pipe 60e on the downstream side of the ultrafiltration device 40 and connected to the raw water tank 10 was exemplified, but in addition to this return pipe 90, For example, return pipes branched from the water supply pipes 60d and 60c and connected to the raw water tank 10 may be provided. As a result, the purified water and the water to be treated in the water supply pipe 60 can be circulated more efficiently as needed.

Further, in the above-described embodiment, the purified water supply system 1 includes the raw water tank 10, the reverse osmosis membrane device 20, the electrodeionization device (EDI device) 30, the ultrafiltration device 40, and the purified water tank 50. , but it is not limited to this configuration, and may be configured to include other devices such as a heat exchanger, an ultraviolet device, and the like.

Further, in the above-described embodiment, the electrodeionization device 30 was described as an example of the ion exchange device, but the ion exchange device may be a so-called ion exchange resin tower.

In addition, the present invention is suitable for producing and supplying purified water for use in pharmaceutical solutions such as water for injection, but of course it can also be applied to producing and supplying purified water for other uses. is possible.

REFERENCE SIGNS LIST 1 Purified water supply system 10 Raw water tank 20 Reverse osmosis membrane device 30 Electrodeionization device 40 Ultrafiltration device 50 Purified water tank 60 Water supply pipe 61 First Valve 62 Second valve 70 Water pump 80 Supply pipe 81 First circulation pipe 82 Second circulation pipe 83 Supply pump 84 First discharge pipe 85 Second discharge pipe , 90... return pipe, 100... control device, 101... supply amount adjusting means, 102... voltage control means, 110... liquid level sensor, UP... use point

One aspect of the present invention for achieving the above object is a raw water tank in which raw water is stored, a reverse osmosis membrane device arranged downstream of the raw water tank, and a reverse osmosis membrane device arranged downstream of the reverse osmosis membrane device. an electrodeionization device, an ultrafiltration device arranged downstream of the electrodeionization device , and a purified water tank in which purified water that has passed through the ultrafiltration device is stored, A purified water supply system for supplying purified water from a purified water tank to a point of use, comprising the raw water tank, the reverse osmosis membrane device, the electrodeionization device , the ultrafiltration device, and the purified water A tank is connected in series by a water supply line, and is provided by branching from the water supply line on the downstream side of the ultrafilter, and the purified water that has passed through the ultrafilter is supplied to the ultrafilter. a supply amount adjusting means for adjusting the amount of purified water supplied to the purified water tank according to a change in the amount of purified water used at the point of use, and the electricity and voltage control means for controlling the applied voltage of the deionization apparatus, wherein the voltage control means changes the applied voltage according to the water flow rate of the electrodeionization apparatus. in the system.

Claims (5)

a raw water tank in which raw water is stored;
a reverse osmosis membrane device arranged downstream of the raw water tank;
an ion exchange device arranged downstream of the reverse osmosis membrane device;
an ultrafiltration device arranged downstream of the ion exchange device;
A purified water tank in which purified water that has passed through the ultrafiltration device is stored,
A purified water supply system for supplying purified water from the purified water tank to a point of use,
The raw water tank, the reverse osmosis membrane device, the ion exchange device, the ultrafiltration device, and the purified water tank are connected in series by a water supply line,
characterized by having a return line branched from the water supply line on the downstream side of the ultrafilter and returning purified water that has passed through the ultrafilter to the upstream side of the ultrafilter. purified water supply system. The purified water supply system according to claim 1,
A purified water supply system, wherein the return line is connected to the raw water tank. The purified water supply system according to claim 1 or 2,
A purified water supply system comprising supply amount adjusting means for adjusting an amount of purified water supplied to the purified water tank according to a change in the amount of purified water used at the point of use. The purified water supply system according to claim 3,
The ion exchange device is an electrodeionization device,
A voltage control means for controlling the voltage applied to the electrodeionization device,
The purified water supply system, wherein the voltage control means changes the applied voltage according to the amount of water flowing through the electrodeionization device. The purified water supply system according to claim 4,
The purified water supply system, wherein the voltage control means lowers the applied voltage as the amount of water flowing through the electrodeionization device decreases.

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