JP3995704B1 - Water treatment system for drinking water production and operation method thereof - Google Patents

Abstract

A water treatment system for producing drinking water and a method for operating the same are provided that can desalinate seawater and are small enough to be mounted on a high mobility vehicle.
The water treatment system for drinking water production according to the present invention is configured to cause the permeated water of a subsequent RO membrane device (low pressure RO membrane device) to flow backward to the outlet side of the preceding RO membrane device (high pressure RO membrane device) when operation is stopped. No need for a sackback tank. In addition, since the treated water of the MF membrane separation device or the UF membrane separation device is supplied to the upstream RO membrane device and the downstream RO membrane device arranged in series using a single pressure pump, Multiple pressurizing pumps are not required. As a result, the system has been downsized to such an extent that it can be mounted on high mobility vehicles.
[Selection] Figure 1

Description

  The present invention provides a microfiltration membrane (MF membrane) separation device or an ultrafiltration membrane (UF membrane) separation device using fresh water such as river water or lake water or seawater as raw water, and a reverse osmosis membrane in the previous stage (first stage). The present invention relates to a water treatment system for producing drinking water by performing a membrane separation process using a (RO membrane) device and a reverse (second stage) reverse osmosis membrane (RO membrane) device.

  Since the MF membrane or UF membrane has high removal performance of fine particles and the like, it is used as a solid-liquid separation means for separating fine solids, suspended substances, microorganisms and the like contained in raw water. In addition, the MF membrane separation device incorporating the MF membrane or the UF membrane separation device incorporating the UF membrane is easy to operate, and is widely used in the fields of medicine, chemistry, semiconductors, and the like in industry. .

  RO membranes can remove salt, organic substances (trihalomethane, agricultural chemicals, etc.) and fine particles (viable bacteria, dead bacteria, viruses, etc.) in water stably and vigorously. It is used in a wide range. For example, in the fields of pharmaceuticals and semiconductors, it is used for the production of water for injection, ultrapure water, and the like.

  Since the RO membrane has very fine pores, raw water (for example, industrial water) is first pretreated using an MF membrane separation device or a UF membrane separation device, and the treated water is supplied to the RO membrane. It is common to perform membrane separation treatment with a separation device.

  Here, in order to produce drinking water at the time of disasters such as earthquakes and tsunamis, an in-vehicle mobile water purification device using a long hair filtration device and a diatomaceous earth filtration device is disclosed in Patent Document 1 as a purification device for purifying raw water in the affected area. It is disclosed.

  Further, Patent Document 2 discloses a vehicle-mounted fresh water production apparatus including a seawater desalination apparatus using an RO membrane and a contaminated fresh water purification device using a UF membrane.

  A mobile water purification facility comprising a first filter that performs filtration through a rotating filter cylinder, a second filter that performs MF membrane or RO membrane treatment, and a third filter that obtains pure water using the RO membrane. However, this is disclosed in Patent Document 3.

Further, Patent Document 4 discloses a treatment method for treating seawater with high yield by using a reverse osmosis membrane device connected in two stages in series.
Japanese Utility Model Publication No. 62-9997 JP-A-9-141261 JP-A-8-71567 JP 2005-246158 A

  However, the mobile water purifier disclosed in Patent Literature 1 cannot remove chemical substances such as bacteria, viruses, salts, heavy metals, and agricultural chemicals, and when the turbidity of raw water is high, a diatomaceous earth filter Has had the disadvantage of having to be manually backwashed frequently.

  Moreover, since the mobile water purification equipment disclosed in Patent Literature 2 and Patent Literature 3 includes a raw water tank or a tank for storing raw water added with a flocculant, it is difficult to mount the water purification equipment unless it is a large vehicle. is there.

  Further, in the seawater desalination apparatus disclosed in Patent Document 4, a pressure pump is required for each of the RO membrane apparatuses connected in two stages. Furthermore, when the device is stopped, in order to prevent the concentrated high-concentration seawater from accumulating in the previous RO membrane device and the calcium salt etc. from precipitating on the RO membrane, A suck-back tank for supplying water into the upstream RO membrane device is also required. For this reason, it is difficult to mount the seawater desalination apparatus disclosed in Patent Document 4 unless it is a large vehicle.

  On the other hand, roads etc. are depressed in areas affected by earthquakes, etc., or there are obstacles such as debris on the roads, and there are places where large vehicles such as conventional trucks cannot run. In such a case, since it becomes impossible to supply purified water in the stricken area, the use of a small vehicle called a high mobility vehicle that is small and highly mobile that can travel even on some rough roads has been studied.

  However, the size of the carrier bed of the high mobility vehicle is about 2070 mm long × 2000 mm wide × 1175 mm high, and compared to the size of a general large vehicle carrier 4500 mm long × 2990 mm wide × 2080 mm high, the space for water purification equipment It is a big problem that is very limited.

  Here, when the raw water is fresh water such as river water or lake water, it can be used as drinking water if it is treated with one RO membrane device after being treated with the MF membrane separation device or UF membrane separation device. it can. However, when the raw water is seawater, after treating the treated water of the MF membrane separation device or the UF membrane separation device with the RO membrane device (the first stage RO membrane device), another RO membrane device (2 It cannot be used as drinking water unless it is processed by the stage RO membrane device.

  Since the raw water that can be collected in the disaster area may be fresh water or seawater, the mobile drinking water production system is preferably capable of processing seawater. Like the apparatus disclosed in Document 4, a plurality of pressure pumps for suck-back tank and RO membrane treatment are required. For this reason, the drinking water manufacturing system which can respond to seawater has much less space margin to be mounted on a high mobility vehicle than the drinking water manufacturing system dedicated to fresh water.

  An object of the present invention is to provide a water treatment system for producing drinking water that can desalinate raw seawater and is small enough to be mounted on a high mobility vehicle, and an operation method thereof.

  The water treatment system for drinking water production of the present invention and the operation method thereof allow the permeated water (drinking water) of the low-pressure RO membrane device to flow back to the outlet side path of the high-pressure RO membrane device when the operation is stopped. It is characterized by being.

  In addition, since the treated water of the MF membrane separation device or the UF membrane separation device is supplied to the former stage RO membrane device and the latter stage RO membrane device arranged in series using a single pressurizing pump, A plurality of pressurizing pumps is also unnecessary.

Specifically, the present invention
A membrane separator using an MF membrane or a UF membrane;
A pre-stage RO membrane device;
A post-stage RO membrane device,
A water treatment system for producing drinking water that sequentially treats treated water of a membrane separation apparatus with a front-stage RO membrane apparatus and a rear-stage RO membrane apparatus,
The treated water of the membrane separator is supplied to the inlet of the upstream RO membrane device by a pressure pump, and the permeated water outlet of the upstream RO membrane device is connected to the inlet of the downstream RO membrane device without going through the tank and pump,
The system is characterized in that any one of the permeated water side path, the adsorption device, and the drinking water storage tank downstream of the permeated water outlet of the latter stage RO membrane apparatus is connected to the permeated water outlet side path of the former stage RO membrane apparatus. (Claim 1).

The present invention also provides:
A membrane separator using an MF membrane or a UF membrane;
A pre-stage RO membrane device;
A post-stage RO membrane device,
An operation method of a water treatment system for drinking water production in which treated water of a membrane separator is sequentially treated by a front-stage RO membrane separator and a rear-stage RO membrane apparatus,
During operation, the treated water of the membrane separation device is supplied to the inlet of the upstream RO membrane device by a pressure pump, and the permeated water of the upstream RO membrane device is supplied to the inlet of the downstream RO membrane device without passing through the tank and the pump. The RO membrane permeate is obtained from the permeate outlet of the RO membrane device,
At the time of shutdown, when the pressurizing pump is stopped, the permeate treatment of the downstream RO membrane device existing in either the permeate water side passage, the adsorber or the drinking water storage tank downstream of the permeate outlet of the downstream RO membrane device The present invention relates to a method for operating a water treatment system for producing drinking water, characterized in that water is allowed to flow into a permeate outlet side of a front-stage RO membrane device without passing through a rear-stage RO membrane device.

  The water treatment system for drinking water production and the operation method thereof of the present invention have two RO membrane devices (an upstream RO membrane device and a subsequent RO membrane) so that drinking water can be produced even when seawater is used as raw water. Membrane device) are connected in series. For this reason, it is possible to supply the treated water of the membrane separation apparatus to the pre-stage RO membrane apparatus and the post-stage RO membrane apparatus with one pressurizing pump, and between the pre-stage RO membrane apparatus and the post-stage RO membrane apparatus, A pressure pump dedicated to the RO membrane device is not required.

  In addition, since either the permeate side path, the adsorption device or the drinking water storage tank downstream of the permeate outlet of the latter stage reverse osmosis membrane apparatus is connected to the permeate outlet side path of the former stage RO membrane apparatus, the system When the operation is stopped, it is possible to suck back drinking water (fresh water) in the permeated water outlet side path of the subsequent RO membrane device, the adsorption device or the drinking water storage tank to the previous RO membrane device. For this reason, there is no need for a sackback tank for storing the permeated water of the front-stage RO membrane device between the front-stage RO membrane device and the rear-stage RO membrane device, and the configuration of the entire system can be reduced in size and simplified. Become.

  The supply water pressure of the upstream RO membrane device is preferably 6 MPa or more and 8 MPa or less, and the supply water pressure of the downstream RO membrane device is preferably 1 MPa or more and 2 MPa or less (Claims 2 and 6).

  In order to supply the treated water of the membrane separator to the pre-stage RO membrane apparatus and the post-stage RO membrane apparatus with one pressurizing pump, the supply water pressure of the pre-stage RO membrane apparatus is set to 6 MPa or more. The supply water pressure is preferably 1 MPa or more. On the other hand, the higher the supply water pressure of the pre-stage RO membrane device, the larger the pressure pump has to be, which increases the installation space and power consumption. For this reason, it is practical to set the supply water pressure of the front-stage RO membrane device to 8 MPa or less and the supply water pressure of the rear-stage RO membrane device to 2 MPa or less.

  It is preferable to install a booster pump before the pressurizing pump (claims 3 and 7).

  The booster pump pressurizes the suction pump suction side to prevent cavitation of the pressurization pump. In order to prevent cavitation of the pressurizing pump, it is preferable to increase the pressure to 0.1 MPa or more with a booster pump.

  The raw water may be filtered before treatment with the membrane separator (claims 3 and 8).

  If raw water is filtered and the suspended matter is removed, clogging of the MF membrane or UF membrane is prevented, and drinking water can be produced stably for a long period of time. Moreover, filter filtration has the advantage that an installation space is small compared with a long hair filter, and the filter which has various average pore diameters can also be selected according to raw | natural water turbidity.

  The drinking water production water treatment system and its operating method of the present invention requires only one pressure pump and omits the sackback tank, so that the installation space is smaller than the conventional seawater-compatible in-vehicle drinking water production system. And it can save power. Further, since the suck-back tank that is an open system is omitted, the risk that the drinking water is contaminated inside the system can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings as appropriate. Note that the present invention is not limited to these.

  An example of a conventional water treatment system for drinking water production that desalinates seawater is shown in FIG. In this water treatment system, raw water is first sucked into the path 32 by the pumping pump 31 and pretreated by the long hair filter 33 to remove suspended substances in the raw water.

  Next, the treated water of the long hair filter 33 is pressurized (about 0.2 MPa) by the filtration pump 35 installed in the path 34 and supplied to the supply water inlet of the MF membrane separation device 36. Although the MF membrane separation device 36 is used here, a UF membrane separation device may be used.

  The treated water (permeated water) of the MF membrane separation device 36 is stored in the MF membrane treated water tank 38 via the passage 37 on the permeate outlet side. Further, the pressure is increased by the first-stage pressurizing pump 40 installed in the path 39 (about 5 to 7 MPa) and supplied to the supply water inlet of the preceding-stage RO membrane apparatus (here, the high-pressure RO apparatus) 41.

  The permeated water of the high-pressure RO membrane device 41 is stored in the suck back tank 43 through the passage 42 on the permeate outlet side. Next, the permeated water in the sackback tank 43 is pressurized by a second-stage pressurizing pump 45 installed in the path 44 (about 1-2 MPa), and a subsequent-stage RO membrane device (here, a low-pressure RO device) 46. To the feed water inlet.

  And the permeated water of the back | latter stage RO membrane apparatus 46 flows out as drinking water (purified water) from the path | route 47 by the permeated water exit side. At this time, as shown in FIG. 2, the activated carbon adsorption device 48 is often installed in the path 47 to adsorb the purified water.

  In the drinking water production water treatment system shown in FIG. 2, since there are two pressure pumps and a suck-back tank, it is difficult to mount the system on a high mobility vehicle. In addition, there is a lot of power consumption, and there was anxiety about supplying power only with high mobility vehicles.

  Next, an example of the water treatment system for drinking water production of the present invention is shown in FIG. In this water treatment system, first, raw water is absorbed into a path 2 by a pumping pump 1 and pretreated by a prefilter (simple filter) 3 to remove suspended substances in the raw water.

  The treated water of the prefilter 3 is pressurized (about 0.2 MPa) by the filtration pump 5 installed in the path 4, supplied to the feed water inlet of the MF membrane separation device 6, and further through the path 7 MF membrane treated water. Water is stored in the tank 8. Note that a UF membrane separator may be used instead of the MF membrane separator 6.

  The treated water in the MF membrane treated water tank 8 is pressurized to about 0.3 MPa by a booster pump 10 installed in the path 9 and further pressurized to a pressure of 6 MPa or more and 8 MPa or less by a pressurizing pump 11, It is supplied to a supply water inlet of a membrane device (here, a high pressure RO device) 14.

  Then, the permeated water of the upstream RO membrane device 14 is supplied to the supply water inlet of the downstream RO membrane device (here, the low pressure RO device) 17 via the path 15. At this time, since the permeated water in the path 15 is maintained at a water pressure of 1 MPa or more and 2 MPa or less, it can be directly supplied to the subsequent RO membrane device 17 without using a pressure pump.

  The permeated water of the downstream RO membrane device 17 flows out as drinking water (purified water) from the path 18 on the permeate outlet side. At this time, it is preferable to install an activated carbon adsorption device 20 in the path 18 to adsorb purified water.

  The concentrated water from the upstream RO membrane device 14 and the downstream RO membrane device 17 is discharged out of the system from the path 21 and the path 22, respectively. By adjusting the opening degree of the pre-stage RO membrane flow rate adjustment valve 23 and the post-stage RO membrane flow rate adjustment valve 24, the concentrated water amount and the permeated water amount of the pre-stage RO membrane device 14 and the post-stage RO membrane device 17 can be adjusted.

  The suckback path 25 is connected to the path 18, and when the operation of the system is stopped (all pumps are stopped), the permeated water of the rear RO membrane device 17 passes from the path 25 to the path 15 and further to the front RO membrane. Since it can be made to flow backward to the permeate outlet side of device 14, permeate (fresh water) in channel 18 and activated carbon adsorption device 20 can be used as suck back water. The suck back path 25 may be connected to the permeate outlet side piping downstream of the activated carbon adsorbing device 20 or a drinking water storage tank (not shown) installed downstream thereof.

(starting method)
Here, the operation method of the water treatment system for drinking water production of the present invention will be described. When the system is started, first, the front-stage RO membrane flow rate adjustment valve 23 and the rear-stage RO membrane flow rate adjustment valve 24 are fully opened, and the suck-back water supply valve 26 is fully closed.

  Next, the booster pump 10 is started. When the pressure pump inlet side pressure switch 12 detects a pressure equal to or higher than a specified value (for example, 0.05 MPa), the pressure pump 11 is activated.

Based on the indicated value of the upstream RO membrane supply water flow meter 13, the number of revolutions of the pressurizing pump 11 is controlled to adjust the amount of water supplied to the upstream RO membrane device 14. The indicated value of the upstream RO supply water flow meter 13 is preferably a target value of the required supply water amount of the upstream RO membrane device 14 (necessary upstream RO treated water amount / RO recovery rate × 100). For example, when the required upstream RO treatment water amount is 2 m ³ / h and the RO recovery rate is 50%, the required supply water amount (target value) of the upstream RO membrane device 14 is preferably 4 m ³ / h. If the indicated value of the upstream RO supply water flow meter 13 is less than the target value, the number of revolutions of the pressurizing pump 11 is increased to control the indicated value to 4 m ³ / h. Also, if the indicated value of the upstream RO supply water flow meter 13 exceeds the target value, the rotational speed is decreased to control the indicated value to 4 m ³ / h, and the amount of water supplied to the upstream RO membrane device 14 is adjusted. .

  Further, the opening degree of the pre-stage RO membrane flow rate adjustment valve 23 is adjusted based on the instruction value of the pre-stage RO membrane permeate flow meter 16, and the permeate amount of the pre-stage RO membrane device 14 is adjusted. That is, if the indicated value of the upstream RO permeate flow meter 16 is less than the target value (required treated water amount of the upstream RO membrane device 14), the upstream RO membrane device flow rate control valve 23 is closed and the indicated value becomes the target value. To control. If the indicated value of the upstream RO permeate flow meter exceeds the target value, the upstream RO membrane device flow rate control valve 23 is opened to control the indicated value to the target value, and the amount of permeated water of the upstream RO membrane device 14 is controlled. adjust. In addition, when processing seawater, it is preferable to adjust the RO collection | recovery rate of the front | former stage RO membrane apparatus 8 to the range of 40%-60%, and when processing fresh water, the RO collection | recovery rate of the front | former stage RO membrane apparatus 8 Is preferably adjusted to a range of 60% to 90%.

The indicated value of the front-stage RO membrane permeate flow meter 16 becomes a predetermined value (25-30% or more, preferably 30% or more) of a target value (necessary amount of treated water of the front-stage RO membrane device 14: 2 m ³ / h, for example). If so, the opening degree of the rear-stage RO membrane flow rate adjustment valve 24 is adjusted based on the instruction value of the rear-stage RO membrane permeate flow meter 19, and the permeated water amount of the rear-stage RO membrane device 17 is adjusted. That is, when the indicated value of the upstream RO membrane permeate flow meter 16 reaches 30% of the target value (for example, 0.6 m ³ / h), the downstream RO membrane flow rate based on the indicated value of the downstream RO permeate flow meter 19 The opening degree control of the control valve 24 is started.

If the indicated value of the downstream RO permeate flow meter 19 is less than the target value (required treated water amount of the downstream RO membrane device 17: for example, 1.6 m ³ / h), the downstream RO membrane device flow control valve 24 is closed to indicate the value. Is controlled to be a target value (necessary amount of treated water of the rear-stage RO membrane device 17: 1.6 m ³ / h, for example). Further, if the indicated value of the rear-stage RO permeate flow meter 19 exceeds the target value (required amount of treated water of the rear-stage RO membrane device 17: for example, 1.6 m ³ / h), the latter-stage RO membrane device flow control valve 24 is opened to indicate The value is controlled to be 100% of the target value (necessary treated water amount of the downstream RO membrane device 17: 1.6 m ³ / h, for example), and the permeated water amount of the downstream RO membrane device 17 is adjusted.

In order to stabilize the flow rate control, after the indication value of the downstream RO membrane permeate flow meter 19 is first stabilized at a target value (necessary treatment water amount of the downstream RO membrane device 17: for example, 1.6 m ³ / h), The indicated value of the upstream RO membrane permeate flow meter 16 is stabilized at a target value (necessary amount of treated water of the upstream RO membrane device 14: 2 m ³ / h, for example). Further, since the latter stage RO permeate meter 19 is affected by the fluctuation of the former stage RO permeate meter 16, the response of the former stage RO permeate meter 16 is delayed and the target value (necessary treated water amount of the former stage RO membrane device 14) is slowly increased. Move closer to. On the other hand, the latter-stage RO permeated water meter 19 speeds up the response and follows the fluctuation of the former-stage RO permeated water amount. Note that the RO recovery rate of the rear RO membrane device 13 (the amount of treated water of the rear RO membrane device 17 / the amount of supplied water of the rear RO membrane device 17 × 100) is preferably adjusted to a range of 60% to 90%.

(How to stop)
Next, when the system is stopped, the front-stage RO membrane flow rate adjustment valve 23, the rear-stage RO membrane flow rate adjustment valve 24, and the suck-back water supply valve 26 are fully opened, and the pressurizing pump 11 and the booster pump 10 are stopped in this order. Thereby, due to the suck back phenomenon to the upstream RO membrane device 14 that occurs when the pressurizing pump 11 is stopped, the downstream RO membrane permeated water flows into the permeate outlet side of the upstream RO membrane device 14 as suck back water, Damage to the RO membrane of the pre-stage RO membrane device 14 can be prevented. After a certain time (about 10 minutes) necessary for confirming the completion of the suck back phenomenon, all of the upstream RO membrane flow rate adjustment valve 23, the subsequent RO membrane flow rate adjustment valve 24 and the suck back water supply valve 26 are Close and shut down the system. When the system is restarted, the system is operated according to the system startup method described above.

  In addition, it goes without saying that the drinking water production water treatment shown in FIG. 1 can produce drinking water using fresh water as raw water. When raw water is fresh water, the RO recovery rate of the pre-stage RO membrane device 8 is 60% to 90%. It is preferable to adjust to the range of%.

  INDUSTRIAL APPLICABILITY The water treatment system for drinking water production and the operation method thereof according to the present invention are useful as a water treatment system that can be mounted on a vehicle such as a high mobility vehicle dispatched to a disaster area or an area that does not have a drinking water supply facility, and an operation method thereof. is there.

It is a flowchart which shows an example of the water treatment system for drinking water manufacture of this invention. It is a flow figure showing an example of the conventional water treatment system for drinking water manufacture.

Explanation of symbols

1, 31: Pumping pump 2, 32: Path 3: Pre-filter (simple filter)
4, 34: Path 5, 35: Filtration pump 6, 36: MF membrane separator (or UF membrane separator)
7, 37: Path 8, 38: MF membrane treated water tank (or UF membrane treated water tank)
9, 39: path 10: booster pump 11: pressurization pump 12: pressure switch inlet side pressure switch 13: upstream RO membrane supply water flow meter (high pressure RO membrane supply water flow meter)
14, 41: Pre-stage RO membrane device (high pressure RO membrane device)
15, 42: Path 16: Pre-stage RO membrane permeate flow meter (high pressure RO membrane permeate flow meter)
17, 46: Subsequent RO membrane device (low pressure RO membrane device)
18, 47: Route 19: Rear RO membrane permeate flow meter (low pressure RO membrane permeate flow meter)
20, 48: Activated carbon adsorption device 21, 22: Condensate drainage path 23: Pre-stage RO membrane flow rate adjustment valve (high pressure RO membrane flow rate adjustment valve)
24: Rear RO membrane flow rate adjustment valve (low pressure RO membrane flow rate adjustment valve)
25: Suckback system 26: Suckback water supply valve 33: Long hair filter 40: First stage pressurizing pump 43: Suckback tank 45: Second stage pressurizing pump

Claims (8)

A membrane separator using a microfiltration membrane or an ultrafiltration membrane;
Pre-stage reverse osmosis membrane device,
A reverse osmosis membrane device,
A water treatment system for producing drinking water that sequentially treats treated water of a membrane separator with a reverse osmosis membrane device and a reverse osmosis membrane device,
The treated water of the membrane separator is supplied to the inlet of the upstream reverse osmosis membrane device by a pressure pump, and the permeated water outlet of the upstream reverse osmosis membrane device is connected to the inlet of the downstream reverse osmosis membrane device without passing through the tank and the pump,
Any one of the permeated water side path, the adsorption device or the drinking water storage tank downstream of the permeated water outlet of the latter stage reverse osmosis membrane device is connected to the permeated water outlet side path of the former stage reverse osmosis membrane device. Water treatment system for drinking water production.   The water treatment system for drinking water production according to claim 1, wherein the supply water pressure of the upstream reverse osmosis membrane device is 6 MPa or more and 8 MPa or less, and the supply water pressure of the downstream reverse osmosis membrane device is 1 MPa or more and 2 MPa or less.   The water treatment system for drinking water production according to claim 1 or 2, wherein a booster pump is installed in front of the pressure pump.   The water treatment system for drinking water production according to any one of claims 1 to 3, wherein the raw water is filtered and filtered before being treated by the membrane separator. A membrane separator using a microfiltration membrane or an ultrafiltration membrane;
Pre-stage reverse osmosis membrane device,
A reverse osmosis membrane device,
A method for operating a water treatment system for drinking water production in which treated water from a membrane separation device is sequentially treated by a reverse reverse osmosis membrane separation device and a reverse reverse osmosis membrane device.
During operation, treated water from the membrane separation device is supplied to the inlet of the upstream reverse osmosis membrane device by a pressure pump, and the permeated water of the upstream reverse osmosis membrane device is supplied to the inlet of the downstream reverse osmosis membrane device without passing through the tank and pump. And obtaining the reverse osmosis membrane permeated water from the permeate outlet of the reverse osmosis membrane device,
When the operation is stopped, the permeated water of the rear reverse osmosis membrane device existing in either the permeated water side path downstream of the rear reverse osmosis membrane device, the adsorbing device or the drinking water storage tank, A method for operating a water treatment system for producing drinking water, wherein the water treatment system is caused to flow into a permeate outlet side.   The operating method of the water treatment system for drinking water production according to claim 5, wherein the supply water pressure of the upstream reverse osmosis membrane device is 6 MPa or more and 8 MPa or less, and the supply water pressure of the downstream reverse osmosis membrane device is 1 MPa or more and 2 MPa or less.   The operating method of the water treatment system for drinking water manufacture of Claim 5 or 6 which pressurizes raw | natural water with a booster pump before a pressurization pump.   The method for operating a water treatment system for drinking water production according to any one of claims 5 to 7, wherein the raw water is filtered before being treated by the membrane separator.

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