Method for cleaning a reverse osmosis membrane apparatus and apparatus for cleaning a reverse osmosis membrane apparatus

Abstract

To provide a reverse osmosis membrane device washing method and a reverse osmosis membrane device washing device where a washing effect can be properly kept even in a low water temperature period and water permeability of a separation membrane can be efficiently recovered.SOLUTION: A washing method of a reverse osmosis membrane device 2 with a reverse osmosis membrane includes: concentration of washing liquid in a tank 3 storing the washing liquid for washing the reverse osmosis membrane is adjusted to concentration suitable for washing treatment of the reverse osmosis membrane; the washing liquid is pressurized by pumps 1, 4 and warmed by heat generated by the pressurization of the pumps 1, 4; the warmed washing liquid is circulated in the washing liquid tank 3 and the temperature of the washing liquid in the washing liquid tank 3 is adjusted to temperature suitable for the washing treatment of the reverse osmosis membrane; and the washing liquid where concentration and temperature are suitable for the washing treatment of the reverse osmosis membrane is supplied to the reverse osmosis membrane device 2 by using the pumps 1,4.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for cleaning a reverse osmosis membrane device and a cleaning device for a reverse osmosis membrane device.

Background Art

[0002] A reverse osmosis membrane device equipped with a reverse osmosis membrane (RO membrane) can obtain clarified treated water, and thus is used in a wide range of fields such as the food industry and the precision electronics field. In RO membrane treatment, since raw water is filtered to obtain treated water, the surface of the separation membrane is contaminated during long-term filtration operation, and the water permeation performance deteriorates. In order to restore the water permeation performance of the separation membrane, a regular cleaning operation is required.

[0003] For cleaning the RO membrane, an alkaline cleaning solution or an acidic cleaning solution is appropriately selected according to the properties of the contaminants. The cleaning treatment with these cleaning solutions uses the properties of each cleaning solution to dissolve and peel off the contaminants on the surface of the RO membrane. Therefore, if the liquid temperature is low, the cleaning effect may decrease. Therefore, when adjusting the temperature of the cleaning solution, a temporary heater is provided in the cleaning solution tank to heat the cleaning solution to enhance the cleaning effect. However, heating by a heater has various problems such as the need for safety measures such as damage to equipment, fire, and burns due to local heating, and the need for a large-capacity power supply for installation.

[0004] Japanese Unexamined Patent Application Publication No. 2016-185520 (Patent Document 1) describes a cleaning process in which a cleaning solution is supplied to the primary side of a reverse osmosis membrane device, and the cleaning solution flowing out from the primary side of the reverse osmosis membrane device is returned to the suction side of a feed water pump via a return line, and a method of gradually increasing the concentration of the cleaning agent in the cleaning solution supplied to the primary side of the reverse osmosis membrane device to a specified concentration. Patent Document 1 describes increasing the temperature of the circulating cleaning water by utilizing the heat of a feed water pump that introduces raw water into the RO membrane device.

[0005] Japanese Patent Publication No. 2005-46801 (Patent Document 2) describes a water treatment method in which raw water containing iron and / or manganese is directly supplied to an internal pressure type hollow fiber separation membrane, which consists of an internal pressure type hollow fiber reverse osmosis membrane or an internal pressure type hollow fiber nanofiltration membrane, to perform desalination treatment. Patent Document 2 also describes a method in which washing water is supplied to a raw water inlet pipe that introduces raw water to an internal pressure type hollow fiber separation membrane to wash at least the raw water inlet pipe, and the washed water is passed through the raw water inlet pipe without being substantially introduced to the internal pressure type hollow fiber separation membrane. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2016-185520 [Patent Document 2] Japanese Patent Publication No. 2005-46801 [Overview of the project] [Problems that the invention aims to solve]

[0007] The method described in Patent Document 1 allows for heating the cleaning water without using a heater. However, at the start of cleaning, both the concentration and temperature of the cleaning solution are low, and the cleaning effect may not be sufficient. Furthermore, since time is required to heat the cleaning solution to a predetermined temperature and increase its concentration to a specified level, it takes time to achieve the desired effect in the cleaning process.

[0008] The method described in Patent Document 2 states that the amount of chemical solution used for chemical cleaning of the separation membrane can be reduced by washing away and removing turbidity and other substances that have adhered to and accumulated in the raw water inlet pipe before cleaning the separation membrane. However, the method in Patent Document 2 does not describe or suggest the problem of reduced cleaning effectiveness when the temperature of the cleaning solution is low. In addition, in Patent Document 2, the cleaning process takes time because the cleaning of the raw water inlet pipe and the cleaning of the separation membrane are performed in separate processes, and the amount of dilution water and discharge volume of the cleaning chemical solution are relatively large for the overall process.

[0009] In view of the above issues, the present invention provides a method for cleaning a reverse osmosis membrane apparatus and a cleaning apparatus for a reverse osmosis membrane apparatus that can maintain a cleaning effect even during periods of low water temperature and efficiently restore the water permeability performance of the separation membrane. [Means for solving the problem]

[0010] As a result of diligent research to solve the above problems, the inventors of the present invention have found that it is effective to provide a cleaning solution tank for adjusting the concentration and temperature of the cleaning solution, and to heat the cleaning solution with the heat generated by the pump due to the pressurization of the cleaning solution.

[0011] To solve the above problems, in one aspect this disclosure provides a method for cleaning a reverse osmosis membrane apparatus equipped with a reverse osmosis membrane, which includes adjusting the concentration of the cleaning solution in a cleaning solution tank that stores the cleaning solution for cleaning the reverse osmosis membrane to a concentration suitable for cleaning the reverse osmosis membrane, pressurizing the cleaning solution with a pump, warming the cleaning solution using the heat generated by the pump due to the pressurization, circulating the warmed cleaning solution in the cleaning solution tank to adjust the temperature of the cleaning solution in the cleaning solution tank to a temperature suitable for cleaning the reverse osmosis membrane, and supplying the cleaning solution, which has been adjusted to a concentration and temperature suitable for cleaning the reverse osmosis membrane, to the reverse osmosis membrane apparatus using a pump for cleaning.

[0012] In one embodiment, the cleaning method for a reverse osmosis membrane apparatus according to the present invention includes performing a reverse osmosis membrane treatment to obtain permeate water and concentrated water by pressurizing raw water with a raw water pump and supplying the pressurized raw water to the reverse osmosis membrane apparatus, followed by a cleaning treatment. During the reverse osmosis membrane treatment, the cleaning solution in the cleaning solution tank is heated to a certain temperature or higher by circulating it between the cleaning solution pump and the cleaning solution tank via a cleaning solution pump connected to the cleaning solution tank and a circulation line connected between the cleaning solution pump and the cleaning solution tank. In the cleaning treatment, the cleaning solution adjusted to a concentration and temperature suitable for cleaning the reverse osmosis membrane is supplied to the reverse osmosis membrane apparatus via the cleaning solution pump.

[0013] In another embodiment of the reverse osmosis membrane cleaning method according to the present invention, the opening and closing of a first valve connected to a raw water supply pipe that supplies raw water to the reverse osmosis membrane device, a second valve connected to a cleaning solution supply pipe that supplies cleaning solution to the raw water supply pipe, a third valve connected between the second valve and a cleaning solution pump, a fourth valve connected to a circulation line, a fifth valve connected between a concentrated water pipe that carries concentrated water flowing out of the reverse osmosis membrane device and a cleaning solution tank, a sixth valve connected to a concentrated water pipe, and a seventh valve connected to a permeate pipe that carries permeate water flowing out of the reverse osmosis membrane device are controlled. The method includes, when performing reverse osmosis membrane treatment, opening the first, sixth, and seventh valves and closing the second and fifth valves; when heating the cleaning solution, closing the third valve and opening the fourth valve, operating the cleaning solution pump, circulating the cleaning solution in the cleaning solution tank through the circulation line to adjust the opening of the fourth valve, heating the cleaning solution with the heat generated by the cleaning solution pump, and when performing cleaning treatment, closing the first, fourth, sixth, and seventh valves and opening the second, third, and fifth valves, operating the cleaning solution pump, and circulating the cleaning solution between the reverse osmosis membrane device and the cleaning solution tank.

[0014] In yet another embodiment, the cleaning method for a reverse osmosis membrane apparatus according to the present invention further includes, when performing the cleaning process, circulating the cleaning solution between the reverse osmosis membrane apparatus and the cleaning solution tank, closing the second valve, the fifth valve, and the seventh valve, opening the first valve and the sixth valve to send raw water to the reverse osmosis membrane apparatus, and discharging the cleaning solution from the reverse osmosis membrane apparatus.

[0015] In yet another embodiment of the cleaning method for a reverse osmosis membrane apparatus according to the present invention, supplying a cleaning solution to the reverse osmosis membrane apparatus includes stopping the cleaning solution pump, allowing the cleaning solution to stand in the reverse osmosis membrane apparatus for a certain period of time, and then restarting the operation of the cleaning solution pump.

[0016] In yet another embodiment, the cleaning method for a reverse osmosis membrane apparatus according to the present invention further includes, after reverse osmosis treatment, narrowing the opening of a first valve or a second valve and warming the raw water or cleaning solution supplied to the reverse osmosis membrane apparatus with the heat of a raw water pump.

[0017] In yet another embodiment, the cleaning method for a reverse osmosis membrane apparatus according to the present invention includes adjusting the pH of the cleaning solution to 10 or higher.

[0018] In yet another embodiment, the cleaning method for a reverse osmosis membrane apparatus according to the present invention includes adding a surfactant to the cleaning solution.

[0019] In yet another embodiment, the cleaning method for a reverse osmosis membrane apparatus according to the present invention includes adjusting the pH of the cleaning solution to 2 or less.

[0020] In another aspect, the present invention is a cleaning device for a reverse osmosis membrane apparatus that pressurizes raw water with a raw water pump and brings it into contact with a reverse osmosis membrane to obtain concentrated water and permeate water, comprising: a cleaning liquid tank for storing a cleaning liquid for cleaning the reverse osmosis membrane; a cleaning liquid pump for pressurizing the cleaning liquid and supplying it into the reverse osmosis membrane apparatus; a circulation line connected between the cleaning liquid pump and the cleaning liquid tank, which heats the cleaning liquid to a temperature suitable for cleaning the reverse osmosis membrane using the heat generated by the cleaning liquid pump while circulating the cleaning liquid between the cleaning liquid pump and the cleaning liquid tank; a supply line for supplying supply water into the cleaning liquid tank so that the cleaning liquid in the cleaning liquid tank reaches a concentration suitable for cleaning the reverse osmosis membrane; and cleaning liquid piping for supplying the cleaning liquid, which has been adjusted to a concentration and temperature suitable for cleaning the reverse osmosis membrane, to the inlet side of the reverse osmosis membrane apparatus and returning the cleaning liquid discharged from the reverse osmosis membrane apparatus to the cleaning liquid tank.

[0021] In yet another aspect, the present invention relates to a cleaning device for a reverse osmosis membrane device that pressurizes raw water with a raw water pump and brings it into contact with a reverse osmosis membrane to obtain concentrated water and permeated water, the cleaning device including a cleaning liquid tank for storing a cleaning liquid for cleaning the reverse osmosis membrane, a cleaning liquid pump for pressurizing the cleaning liquid and feeding it into the reverse osmosis membrane device, a circulation line connected between the raw water pump and the cleaning liquid tank for warming the cleaning liquid to a temperature suitable for cleaning the reverse osmosis membrane with heat generated from the raw water pump while circulating the cleaning liquid between the raw water pump and the cleaning liquid tank, a supply line for supplying feed water into the cleaning liquid tank so that the cleaning liquid in the cleaning liquid tank reaches a concentration suitable for cleaning the reverse osmosis membrane, and a cleaning liquid pipe for supplying the cleaning liquid adjusted to a concentration and temperature suitable for cleaning the reverse osmosis membrane to the inlet side of the reverse osmosis membrane device and returning the cleaning liquid discharged from the reverse osmosis membrane device to the cleaning liquid tank.

[0022] In one embodiment, the cleaning device for the reverse osmosis membrane device according to the present invention includes a first valve connected to a raw water supply pipe for supplying raw water to the reverse osmosis membrane device, a second valve connected to a cleaning liquid supply pipe for supplying the cleaning liquid to the raw water supply pipe, a third valve connected between the second valve and the cleaning liquid pump, a fourth valve connected to the circulation line, a fifth valve connected between a concentrated water pipe through which concentrated water flowing out of the reverse osmosis membrane device flows and the cleaning liquid tank, a sixth valve connected to the concentrated water pipe, and a seventh valve connected to a permeated water pipe through which permeated water flowing out of the reverse osmosis membrane device flows. When performing reverse osmosis membrane treatment in the reverse osmosis membrane device, the first valve, the sixth valve, and the seventh valve are opened, the second valve and the fifth valve are closed. When warming the cleaning liquid, the third valve is closed, the fourth valve is opened, the cleaning liquid pump is operated, the cleaning liquid in the cleaning liquid tank is circulated through the circulation line, and the opening degree of the fourth valve is adjusted to warm the cleaning liquid with the heat generated by the cleaning liquid pump. When performing the cleaning treatment, the first valve, the fourth valve, the sixth valve, and the seventh valve are closed, the second valve, the third valve, and the fifth valve are opened, the cleaning liquid pump is operated, and the cleaning liquid is circulated between the reverse osmosis membrane device and the cleaning liquid tank.

[0023] In another embodiment, the cleaning device for the reverse osmosis membrane device according to the present invention includes a pH measuring means for measuring the pH of the cleaning liquid in the cleaning liquid tank, and a pH adjusting means for supplying an acid or an alkali into the cleaning liquid tank based on the measurement result of the pH measuring means.

[0024] In yet another embodiment, the cleaning device for the reverse osmosis membrane device according to the present invention further includes a temperature measuring means for measuring the temperature of the cleaning liquid in the cleaning liquid tank, and a notification means capable of notifying when the temperature of the cleaning liquid in the cleaning liquid tank reaches a temperature suitable for the cleaning treatment of the reverse osmosis membrane.

Effects of the Invention

[0025] According to the present invention, it is possible to provide a cleaning method for a reverse osmosis membrane device and a cleaning device for a reverse osmosis membrane device that can appropriately maintain the cleaning effect even during a low water temperature period and efficiently recover the water permeation performance of the separation membrane.

Brief Description of the Drawings

[0026] [Figure 1] It is a schematic diagram showing an example of a cleaning device for a reverse osmosis membrane device according to the first embodiment of the present invention. [Figure 2] It is a schematic diagram showing an example of a cleaning device for a reverse osmosis membrane device according to the second embodiment of the present invention. [Figure 3] It is a schematic diagram showing an example of a cleaning device for a reverse osmosis membrane device according to the third embodiment of the present invention. [Figure 4] It is a schematic diagram for explaining an example of a cleaning device for an experimental reverse osmosis membrane device used in Example 1 of the present invention. [Figure 5] It is a graph showing an example of the measurement results of the membrane permeation flux of a new reverse osmosis membrane used in the examples of the present invention, before the cleaning treatment, and after the cleaning treatment (cleaning 1, cleaning 2). [Figure 6] ​​​​​​This graph shows an example of the change in membrane permeation flux of the reverse osmosis membrane used in Example 3 of the present invention. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, identical or similar parts are denoted by identical or similar reference numerals. The embodiments shown below are illustrative examples of devices and methods for realizing the technical idea of ​​this invention, and the technical idea of ​​this invention is not limited to the structure, arrangement, etc., of the components described below.

[0028] (First Embodiment) As shown in Figure 1, the cleaning device for the reverse osmosis membrane apparatus 2 according to the first embodiment of the present invention includes a cleaning liquid tank 3 for storing cleaning liquid, a cleaning liquid pump 4 for pressurizing the cleaning liquid and supplying it into the reverse osmosis membrane apparatus 2 equipped with a reverse osmosis membrane, a circulation line 8 connected between the cleaning liquid pump 4 and the cleaning liquid tank 3, which heats the cleaning liquid to a temperature suitable for cleaning the reverse osmosis membrane using the heat generated from the cleaning liquid pump while circulating the cleaning liquid between the cleaning liquid pump and the cleaning liquid tank, a supply line (supply water pipe 12, permeate water pipe 11) for supplying supply water into the cleaning liquid tank 3 so that the cleaning liquid in the cleaning liquid tank 3 becomes a concentration suitable for cleaning the reverse osmosis membrane, and cleaning liquid piping (cleaning liquid supply pipe 9, cleaning liquid return pipe 10) for supplying cleaning liquid adjusted to a concentration and temperature suitable for cleaning the reverse osmosis membrane to the inlet side of the reverse osmosis membrane apparatus 2 and returning the cleaning liquid discharged from the reverse osmosis membrane apparatus 2 to the cleaning liquid tank 3.

[0029] Raw water is pressurized by the raw water pump 1 and then subjected to reverse osmosis treatment by contacting it with the reverse osmosis membrane of the reverse osmosis membrane device 2 to obtain concentrated water and permeate. The raw water pump 1 is connected to the raw water supply pipe 5, which supplies raw water to the reverse osmosis membrane device 2. Permeate flowing out of the reverse osmosis membrane device 2 is discharged to the outside via the permeate pipe 6 connected to the reverse osmosis membrane device 2. Concentrated water flowing out of the reverse osmosis membrane device 2 is discharged to the outside via the concentrated water pipe 7 connected to the reverse osmosis membrane device 2. The concentrated water pipe 7 is connected to the cleaning liquid return pipe 10, which is connected to the cleaning liquid tank 3. The cleaning liquid returned via the cleaning liquid return pipe 10 is stored in the cleaning liquid tank 3 and then supplied as cleaning liquid to the reverse osmosis membrane device 2 via the cleaning liquid supply pipe 9 connected to the raw water supply pipe 5.

[0030] Permeate pipe 6 is connected to permeate pipe 11, which is connected to the cleaning solution tank 3. Permeate pipe 11 functions as a supply line that supplies permeate water to adjust the concentration of the cleaning solution in the cleaning solution tank 3. The cleaning solution tank 3 is further connected to a supply water pipe 12 that supplies supply water from the outside into the cleaning solution tank 3 to adjust the concentration of the cleaning solution in the cleaning solution tank 3. In the example shown in Figure 1, permeate pipe 11 and supply water pipe 12 are connected to the cleaning solution tank 3 separately, but permeate pipe 11 and supply water pipe 12 may be connected to each other by a valve (not shown) or the like, which is located upstream of the cleaning solution tank 3.

[0031] The cleaning device of the reverse osmosis membrane apparatus 2 includes a first valve V11 connected to the raw water supply pipe 5, a second valve V12 connected to the cleaning liquid supply pipe 9 that supplies cleaning liquid to the raw water supply pipe 5, a third valve V13 positioned between the second valve V12 and the cleaning liquid pump 4, a fourth valve V14 connected to the circulation line 8, a fifth valve V15 connected between the concentrated water pipe 7 that carries concentrated water flowing out of the reverse osmosis membrane apparatus 2 and the cleaning liquid tank 3, a sixth valve V16 connected to the concentrated water pipe 7, and a seventh valve V17 connected to the permeate pipe 6 that carries permeate water flowing out of the reverse osmosis membrane apparatus 2.

[0032] In the example shown in Figure 1, the first valve V11 is located between the raw water pump 1 and the reverse osmosis membrane device 2. Further downstream of the first valve V11 (towards the reverse osmosis membrane device 2), the raw water supply pipe 5 is connected to the washing liquid supply pipe 9.

[0033] During normal operation of the reverse osmosis membrane apparatus 2, that is, when reverse osmosis treatment is performed in the reverse osmosis membrane apparatus 2, the first valve V11, the sixth valve V16, and the seventh valve V17 are opened, and the second valve V12 and the fifth valve V15 are closed. As a result, the raw water is pressurized by the raw water pump 1 and supplied into the reverse osmosis membrane apparatus 2, yielding permeate and concentrated water. The permeate can be supplied to each user from the permeate piping 6 according to the application. The concentrated water, having concentrated components of the raw water, is typically discharged to the outside from the concentrated water piping 7, but it can also be reused if the water quality is suitable for the application.

[0034] The concentration and temperature of the cleaning solution are adjusted in the cleaning solution tank 3. Typically, the undiluted cleaning solution is stored in the cleaning solution tank 3. The supply water for diluting the undiluted cleaning solution to a predetermined concentration is supplied via the permeate pipe 11 or the supply water pipe 12. The type of supply water is not particularly limited. Permeate supplied from the permeate pipe 11 may also be used as supply water. If the raw water has low turbidity and relatively good water quality and clarity, it is also possible to use a portion of the raw water as supply water.

[0035] The concentration of the cleaning solution is adjusted according to the expected membrane contamination status of the reverse osmosis membrane equipped in the reverse osmosis membrane apparatus 2. The membrane contamination status can be determined to some extent from the operating status of the reverse osmosis membrane apparatus 2. For example, if a decrease in the water permeability performance of the reverse osmosis membrane due to organic contamination is suspected, cleaning with an alkaline cleaning solution is highly effective. Also, if a decrease in the water permeability performance of the reverse osmosis membrane due to the adhesion of metals is suspected, cleaning with an acidic cleaning solution is highly effective. According to this embodiment, a cleaning solution with a concentration and temperature suitable for cleaning the reverse osmosis membrane is adjusted in advance according to the expected contamination status of the reverse osmosis membrane. Then, by cleaning the reverse osmosis membrane with a high-concentration and heated cleaning solution from the start of cleaning, the water permeability performance of the separation membrane can be restored efficiently in a short time.

[0036] The type of alkaline cleaning solution is not particularly limited, and general cleaning solutions used for cleaning reverse osmosis membranes can be used. The pH of the cleaning solution is adjusted to be 10 or higher, preferably 11 or higher, and more preferably around 11 to 12. For example, the pH of the cleaning solution may drop below 10 due to heating or circulation treatment of the cleaning solution, as described later. In such cases, it is preferable to adjust the pH of the cleaning solution by adding caustic soda, which acts as a cleaning agent, to the undiluted cleaning solution. Furthermore, it is preferable to add a surfactant to the cleaning solution in order to further enhance the cleaning effect of the reverse osmosis membrane. For example, it is preferable to add 0.1 to 5% by weight of the surfactant relative to the cleaning solution contained in the cleaning solution tank 3, and more preferably 1 to 2% by weight.

[0037] The type of acidic cleaning solution is not particularly limited, and general cleaning solutions used for cleaning reverse osmosis membranes can be used. Hydrochloric acid, sulfuric acid, citric acid, etc., can be used as added acids. For hydrochloric acid and sulfuric acid, it is preferable to add the cleaning agent to the stock solution so that the pH of the cleaning solution is around 2, or even 2 or less. For citric acid, it is preferable to adjust the concentration to, for example, about 2% by weight of the cleaning solution contained in the cleaning solution tank 3. Depending on the degree of contamination of the reverse osmosis membrane, it is possible to provide a cleaning solution tank 3 containing an alkaline cleaning solution and a cleaning solution tank 3 containing an acidic cleaning solution, and perform acid cleaning after rinsing with raw water or the like following alkaline cleaning to further enhance the cleaning effect of the reverse osmosis membrane.

[0038] The cleaning solution in the cleaning solution tank 3 is adjusted to a temperature suitable for cleaning the reverse osmosis membrane. When heating the cleaning solution, the third valve V13 is closed and the fourth valve V14 is opened, and the cleaning solution pump 4 is operated. The cleaning solution in the cleaning solution tank 3 is circulated through the circulation line 8, and the opening of the fourth valve V14 is adjusted, so that the cleaning solution is heated by the heat generated by the cleaning solution pump 4. In addition, because the cleaning solution circulates between the cleaning solution tank 3 and the cleaning solution pump 4 through the circulation line 8, a liquid flow is generated in the cleaning solution tank 3, which allows the cleaning solution in the cleaning solution tank 3 to be mixed, thereby making the concentration of the cleaning solution uniform.

[0039] The specific configuration of the circulation line 8 is not particularly limited, but in order to create a liquid flow within the cleaning liquid tank 3 and promote the homogenization of the cleaning liquid concentration, for example, the cleaning liquid can be drawn out from the bottom of the cleaning liquid tank 3. The circulation line 8 can then be arranged to return the cleaning liquid to the cleaning liquid tank 3 from the top of the tank or near the liquid surface. This allows the cleaning liquid in the cleaning liquid tank 3 to be mixed using the circulation line 8, thereby reducing the power required for stirring. It is also preferable to install a line mixer in the middle of the circulation line 8 to promote stirring of the cleaning liquid.

[0040] Furthermore, by placing insulating material around the outer circumference of the piping that makes up the circulation line 8 to promote the heating of the cleaning fluid in the circulation line 8, heat loss as the fluid flows through the circulation line 8 can be suppressed. If the length of the piping in the circulation line 8 is too long or the flow rate is too low, the temperature of the cleaning fluid may be low, especially in cold weather.

[0041] The length of the circulation line 8 is preferably adjusted so that the cleaning fluid is sufficiently heated by the heat generated by the cleaning fluid pump 4. It is also preferable to adjust the flow rate of the cleaning fluid circulated in the circulation line 8 according to the ambient temperature. In one embodiment, although not limited to the following, the volume is 1 m³. 3 The cleaning fluid pump 4 has the capacity to circulate the cleaning fluid in the cleaning fluid tank 3 at a maximum rate of 650 L / min. By installing a cleaning fluid pump 4 that has the capacity to replace the cleaning fluid in the cleaning fluid tank 3 in, for example, approximately 1.5 minutes, the cleaning fluid can be thoroughly mixed and heated easily.

[0042] The cleaning solution tank 3 may be equipped with a temperature measuring means 31 for measuring the temperature of the cleaning solution inside the tank 3 and a pH measuring means 32 for measuring the pH of the cleaning solution inside the tank 3. A thermometer or the like can be used as the temperature measuring means 31. A pH meter or the like that can measure the pH of the cleaning solution inside the tank 3 continuously or in batches can be used as the pH measuring means 32. In addition, to maintain the temperature of the cleaning solution inside the tank 3, it is also effective to provide insulating material on the outside of the tank 3 to suppress heat dissipation.

[0043] Furthermore, it is preferable that the cleaning solution tank 3 includes an opening adjustment means 20 for adjusting the opening degree of the fourth valve V14 according to the temperature of the cleaning solution in the cleaning solution tank 3, a pH adjustment means 21 for supplying acid or alkali into the cleaning solution tank 3 based on the measurement results of the pH measuring means 32, and a notification means 22 capable of notifying the operator when the temperature of the cleaning solution in the cleaning solution tank 3 reaches a temperature suitable for cleaning the reverse osmosis membrane. The specific configuration of the notification means 22 is not limited, but is not particularly limited as long as it is a device capable of notifying the operator of the temperature and state of the cleaning solution (concentration, holding time, etc.) using sound, light, vibration, diagrams, text, etc.

[0044] If the temperature of the cleaning solution supplied to the reverse osmosis membrane apparatus 2 is too low, the desired cleaning effect may not be sufficiently obtained. While a higher temperature of the cleaning solution increases its effectiveness, if the temperature is too high, contact with the high-temperature cleaning solution may impair the heat resistance of the reverse osmosis membrane and accelerate its deterioration. Considering the heat resistance temperature of the reverse osmosis membrane and piping, it is preferable to set the temperature of the cleaning solution to 45°C or lower, and more preferably 40°C or lower.

[0045] According to this embodiment, the temperature of the cleaning solution can be easily adjusted by adjusting the opening of the fourth valve V14 using the opening adjustment means 20. For example, increasing the opening of the fourth valve V14 can accelerate the temperature rise of the cleaning solution. Furthermore, the notification means 22 can notify the operator when the cleaning solution has reached a predetermined temperature, so the operator can stop the cleaning solution pump 4 or close the fourth valve V14 to temporarily halt temperature control as needed. This helps to suppress an excessive temperature rise of the cleaning solution.

[0046] Furthermore, because the pH is properly adjusted by the pH adjustment means 21, a cleaning solution with a concentration and temperature that provides sufficient cleaning effect can be supplied to the reverse osmosis membrane device 2 from the start of supplying the cleaning solution to the reverse osmosis membrane device 2, thus enabling efficient cleaning of the reverse osmosis membrane. In addition, the notification means 22 makes it easier for the operator to understand when the cleaning solution is ready to be supplied, allowing the cleaning process to be performed more efficiently at a more appropriate timing.

[0047] When cleaning the reverse osmosis membrane using the cleaning solution contained in the cleaning solution tank 3, the first valve V11, the fourth valve V14, the sixth valve V16, and the seventh valve V17 are closed, and the second valve V12, the third valve V13, and the fifth valve V15 are opened. Furthermore, the cleaning solution pump 4 is operated to supply the cleaning solution from the cleaning solution supply pipe 9 to the reverse osmosis membrane device 2, and from the reverse osmosis membrane device 2 to the cleaning solution tank 3 via the cleaning solution return pipe 10, thereby circulating the cleaning solution between the reverse osmosis membrane device 2 and the cleaning solution tank 3.

[0048] When cleaning a reverse osmosis membrane, it is preferable to circulate the cleaning solution between the reverse osmosis membrane device 2 and the cleaning solution tank 3, then close the second valve V12, the fifth valve V15, and the seventh valve V17, open the first valve V11 and the sixth valve V16, send raw water to the reverse osmosis membrane device 2, and discharge the cleaning solution from the reverse osmosis membrane device 2. A portion of the permeate water may be used instead of raw water. In this way, after discharging the cleaning solution from the reverse osmosis membrane device 2, supplying raw water to the primary side of the reverse osmosis membrane and performing a rinsing treatment can enhance the cleaning effect of the reverse osmosis membrane. Furthermore, when performing acid cleaning and alkaline cleaning on the reverse osmosis membrane device 2, supplying raw water to the reverse osmosis membrane device 2 after the completion of one cleaning treatment can suppress the generation of scale and other deposits inside the reverse osmosis membrane device 2 due to the supply of cleaning solutions with different properties.

[0049] In another embodiment, when supplying the cleaning solution to the reverse osmosis membrane apparatus 2, it is preferable to temporarily stop the cleaning solution pump 4, allow the cleaning solution to stand in the reverse osmosis membrane apparatus 2 for a certain period of time, and then restart the operation of the cleaning solution pump 4. By providing a standing time during which the cleaning solution stands in the reverse osmosis membrane apparatus 2, contaminants are detached from the surface of the reverse osmosis membrane during this standing time. Then, by restarting the operation of the cleaning solution pump 4 and recirculating the cleaning solution, the contaminants detached during the standing time can be flushed out of the reverse osmosis membrane apparatus 2.

[0050] The circulation time of the cleaning solution can be set arbitrarily, but it is expected that the longer the contact time between the cleaning solution and the surface of the reverse osmosis membrane, the higher the cleaning effect. For example, by circulating the cleaning solution for 15 minutes, then stopping the circulation, letting it stand for about 3 hours, and then circulating it again for about 15 minutes, the reverse osmosis membrane can be cleaned efficiently.

[0051] In other words, during the washing process, an alkaline or acidic washing solution is present on the primary side of the reverse osmosis membrane, with a high solute concentration present. On the secondary side (persemite side), permeate water with a low solute concentration is present, causing the permeate water to move from the secondary side to the primary side via forward osmosis. In a stationary state, the primary side is not pressurized, making it easier for forward osmosis to occur, and the flow of permeate water due to forward osmosis can be expected to remove contaminants from the membrane surface. For this reason, after circulating the washing solution, a standing time is provided to promote the removal of contaminants. In this case, if the seventh valve V17 is closed, it is possible that the permeate water will not flow easily to the primary side. Therefore, it is also possible to provide a small-capacity permeate water buffer tank (not shown) between the reverse osmosis membrane device 2 and the seventh valve V17 to promote the permeate water to flow to the primary side of the reverse osmosis membrane via forward osmosis. After cleaning, the first valve V11 and the sixth valve V16 are opened, and the second valve V12, the fifth valve V15, and the seventh valve V17 are closed. Raw water is supplied at low pressure to rinse the inside of the reverse osmosis membrane device 2, and then the system is returned to normal operation.

[0052] After reverse osmosis membrane treatment and before the washing treatment, the opening of the first valve V11 may be reduced to preheat the raw water supplied to the reverse osmosis membrane device 2 using the heat from the raw water pump 1. By introducing raw water heated by the heat generated by the raw water pump 1 into the reverse osmosis membrane device 2 in advance, the inside of the reverse osmosis membrane device 2 can be heated before the washing treatment. This reduces the effect of temperature drop of the washing solution due to the flow of liquid through the piping, even in cold weather, and allows for a more effective washing of the washing solution.

[0053] The cleaning method for the reverse osmosis membrane apparatus 2 according to the first embodiment of the present invention can be carried out using the cleaning apparatus for the reverse osmosis membrane apparatus 2 shown in Figure 1. Specifically, the cleaning method for the reverse osmosis membrane apparatus 2 according to the first embodiment includes adjusting the cleaning solution in the cleaning solution tank 3, which stores the cleaning solution for cleaning the reverse osmosis membrane, to a concentration suitable for cleaning the reverse osmosis membrane, pressurizing the cleaning solution with the cleaning solution pump 4, warming the cleaning solution using the heat generated by the pressurization from the cleaning solution pump 4, circulating the warmed cleaning solution into the cleaning solution tank 3 to adjust the temperature of the cleaning solution in the cleaning solution tank 3 to a temperature suitable for cleaning the reverse osmosis membrane, and supplying the cleaning solution, which has been adjusted to a concentration and temperature suitable for cleaning the reverse osmosis membrane, to the reverse osmosis membrane apparatus 2 using the cleaning solution pump 4 for cleaning.

[0054] According to the cleaning apparatus and cleaning method for a reverse osmosis membrane apparatus 2 of the first embodiment of the present invention, the cleaning liquid pump 4 connected to the cleaning liquid tank 3, the fourth valve V14, and the circulation line 8 can maintain the cleaning liquid at a temperature suitable for cleaning the reverse osmosis membrane and maintain a uniform concentration of the cleaning liquid. Since the temperature and concentration of the cleaning liquid can be maintained while the raw water is being treated with the reverse osmosis membrane, a cleaning liquid with a high cleaning effect can be supplied into the reverse osmosis membrane apparatus 2 at the optimal timing. As a result, the cleaning effect of the cleaning liquid can be obtained efficiently and in a short time even at low water temperatures. Furthermore, since the cleaning liquid pump 4 only needs to be a pump of a size sufficient to circulate the cleaning liquid between the cleaning liquid tanks 3 and within the reverse osmosis membrane apparatus 2, the apparatus can be made smaller and maintenance is relatively easy compared to the raw water pump 1 which is required to apply pressure to the raw water for reverse osmosis treatment. As a result, according to the cleaning apparatus and cleaning method for a reverse osmosis membrane apparatus 2 of the first embodiment, the cleaning effect can be appropriately maintained even at low water temperatures, and the water permeability performance of the separation membrane can be efficiently restored.

[0055] (Second Embodiment) The cleaning device of the reverse osmosis membrane apparatus 2 according to the second embodiment of the present invention differs from the reverse osmosis membrane apparatus 2 according to the second embodiment of the present invention in that, as shown in Figure 2, the cleaning liquid supply pipe 9 that supplies the cleaning liquid in the cleaning liquid tank 3 to the reverse osmosis membrane apparatus 2 is connected between the first valve V21, which is connected to the raw water supply pipe 5 that supplies raw water, and the raw water pump 1.

[0056] As shown in Figure 2, the cleaning device of the reverse osmosis membrane apparatus 2 according to the second embodiment includes a first valve V21, a second valve V22 connected to a cleaning liquid supply pipe 9 that supplies cleaning liquid to the raw water supply pipe 5, a third valve V23 positioned between the second valve V22 and the cleaning liquid pump 4, a fourth valve V24 connected to a circulation line 8, a fifth valve V25 connected between a concentrated water pipe 7 that carries concentrated water flowing out of the reverse osmosis membrane apparatus 2 and a cleaning liquid tank 3, a sixth valve V26 connected to the concentrated water pipe 7, and a seventh valve V27 connected to a permeate pipe 6 that carries permeate water flowing out of the reverse osmosis membrane apparatus 2. Since the first to seventh valves V21 to V27 have substantially the same configuration as the first to seventh valves V11 to V17 in Figure 1, a detailed explanation is omitted.

[0057] In the second embodiment of the reverse osmosis membrane apparatus 2 cleaning device and cleaning treatment method, while performing normal reverse osmosis membrane treatment using the reverse osmosis membrane apparatus 2, the cleaning liquid in the cleaning liquid tank 3 is circulated between the cleaning liquid pump 4 connected to the cleaning liquid tank 3 and the cleaning liquid tank 3 via a circulation line 8 connected between the cleaning liquid pump 4 and the cleaning liquid tank 3, thereby heating it to a certain temperature or higher. For the cleaning treatment, a cleaning liquid adjusted to a concentration and temperature suitable for cleaning the reverse osmosis membrane can be supplied to the reverse osmosis membrane apparatus 2 via the cleaning liquid pump 4, so that the cleaning effect can be appropriately maintained even during periods of low water temperature.

[0058] In the reverse osmosis membrane apparatus 2 according to the second embodiment, the procedure may further include, after the reverse osmosis membrane treatment and before the washing treatment, a process in which the opening of the first valve V21 or the second valve V22 is narrowed and the raw water or washing solution supplied to the reverse osmosis membrane apparatus 2 is heated by the heat of the raw water pump 1. By heating the raw water or washing solution supplied to the reverse osmosis membrane apparatus 2 by the heat of the raw water pump 1 before the washing solution is supplied in the washing treatment, it is possible to further enhance the washing effect of the washing solution.

[0059] (Third embodiment) The cleaning device for the reverse osmosis membrane apparatus 2 according to the third embodiment of the present invention, as shown in Figure 3, is a cleaning device for the reverse osmosis membrane apparatus 2 that pressurizes raw water with a raw water pump 1 and brings it into contact with a reverse osmosis membrane to obtain concentrated water and permeate water, and comprises a cleaning liquid tank 3 for storing cleaning liquid for cleaning the reverse osmosis membrane apparatus 2, a cleaning liquid pump 4 for pressurizing the cleaning liquid and supplying it into the reverse osmosis membrane apparatus 2, and a connection between the raw water pump 1, which is connected to a raw water supply pipe 5 that supplies raw water to the reverse osmosis membrane apparatus 2, and the cleaning liquid tank 3, and circulates the cleaning liquid between the raw water pump 1 and the cleaning liquid tank 3. The system includes a circulation line 8 that uses heat generated from the raw water pump 1 to heat the water to a temperature suitable for cleaning the reverse osmosis membrane, a supply line (supply water pipe 12, permeate pipe 11) that supplies water into the cleaning solution tank 3 so that the cleaning solution in the tank 3 reaches a concentration suitable for cleaning the reverse osmosis membrane, and cleaning solution piping (cleaning solution supply pipe 9, cleaning solution return pipe 10) that supplies the cleaning solution, adjusted to a concentration and temperature suitable for cleaning the reverse osmosis membrane, to the inlet side of the reverse osmosis membrane device 2 and returns the cleaning solution discharged from the reverse osmosis membrane device 2 to the cleaning solution tank 3.

[0060] The cleaning device of the reverse osmosis membrane apparatus 2 according to the third embodiment includes a first valve V31 connected to the raw water supply pipe 5, a second valve V32 connected to the cleaning liquid supply pipe 9 that supplies cleaning liquid to the raw water supply pipe 5, a third valve V33 connected between the raw water pump 1 and the reverse osmosis membrane apparatus 2, a fourth valve V34 connected to the circulation line 8, a fifth valve V35 connected between the concentrated water pipe 7 that carries concentrated water flowing out of the reverse osmosis membrane apparatus 2 and the cleaning liquid tank 3, a sixth valve V36 connected to the concentrated water pipe 7, and a seventh valve V37 connected to the permeate pipe 6 that carries permeate water flowing out of the reverse osmosis membrane apparatus 2. Since the first to seventh valves V31 to V37 have substantially the same configuration as the first to seventh valves V11 to V17 in Figure 1, a detailed explanation is omitted.

[0061] When performing reverse osmosis membrane treatment in the reverse osmosis membrane apparatus 2, the first valve V31, the third valve V33, the sixth valve V36, and the seventh valve V37 are opened, and the second valve V32, the fourth valve V34, and the fifth valve V35 are closed. When performing cleaning treatment of the reverse osmosis membrane using the cleaning solution contained in the cleaning solution tank 3, the first valve V31, the third valve V33, the fifth valve V35, the sixth valve V36, and the seventh valve V37 are closed, and the opening of the fourth valve V34 is reduced, so that the cleaning solution in the cleaning solution tank 3 is circulated through the cleaning solution supply pipe 9, the raw water supply pipe 5, and the circulation line 8. At this time, the cleaning solution passing through the cleaning solution supply pipe 9, the raw water supply pipe 5, and the circulation line 8 is heated by the heat from the raw water pump 1. After the cleaning solution in the cleaning solution tank 3 reaches a temperature suitable for cleaning the reverse osmosis membrane, the raw water pump 1 is temporarily stopped, the first valve V31, the fourth valve V34, the sixth valve V36, and the seventh valve V37 are closed, and the second valve V32, the third valve V33, and the fifth valve V35 are opened. The raw water pump 1 is then restarted to supply the cleaning solution to the primary side of the reverse osmosis membrane in the reverse osmosis membrane device 2 and return it to the cleaning solution tank 3 in a circulating operation, thereby cleaning the reverse osmosis membrane. The method of circulating the cleaning solution is desirable because, as in the first embodiment, combining circulation operation and standing is expected to enhance the peeling effect of membrane contaminants.

[0062] In the third embodiment, the raw water pump 1 is used to homogenize and heat the cleaning solution. Unlike the first and second embodiments, the cleaning solution pump 4 can be omitted, which reduces the initial cost of the equipment. On the other hand, in order to homogenize and heat the cleaning solution, it is necessary to stop the normal filtration operation, which may make the operation more complicated. The cleaning method according to the third embodiment also provides the same effect as the cleaning methods according to the first and second embodiments from the viewpoint of membrane cleaning, but there are differences in operation and initial cost, so it is preferable to adopt one of the configurations according to the purpose of the equipment.

[0063] As described above, the present invention has been described by the embodiments described above, but the discussion and drawings that constitute part of this disclosure should not be understood as limiting the invention. That is, this disclosure is not limited to the embodiments described above, and it goes without saying that the components can be combined and modified to embody the invention without departing from its essence. [Examples]

[0064] Examples of the present invention are shown below along with comparative examples. These examples are provided to help you better understand the present invention and its advantages, and are not intended to limit the invention.

[0065] (Example 1: Effect of heating) In Example 1, the cleaning effect of RO membranes by heating was evaluated. RO membrane elements with reduced water permeability were recovered from an RO membrane treatment facility operating in a food factory, disassembled, and a portion of the contaminated reverse osmosis membrane was cut out and used for testing. The contaminated RO membrane was used in the experimental reverse osmosis membrane apparatus 2a (effective membrane area 60 cm²) shown in Figure 4. 2 The apparatus was set up, and a cleaning solution containing a cleaning agent was circulated to the primary side of the RO membrane using a cleaning solution pump 4a. The raw water side piping and concentrated water side piping of the experimental reverse osmosis membrane apparatus 2a were connected to the cleaning solution tank 3a, creating a configuration that allowed the cleaning solution to circulate on the primary side of the RO membrane. The cleaning solution described later was added to the cleaning solution tank 3a, and the cleaning solution was circulated. Valve V47 on the permeate side piping of the experimental reverse osmosis membrane apparatus 2a was closed during circulation operation and open during standing.

[0066] In Example 1, a cleaning solution containing an alkaline agent and a surfactant was used, and the pH was adjusted to approximately 12 before the cleaning operation. The cleaning conditions in Example 1 are shown in Table 1. In cleaning 1, the temperature of the cleaning solution was set to room temperature (22-24°C), and in cleaning 2, the cleaning solution was heated and set to 30-33°C. In both cleaning conditions, the RO membrane was cleaned by repeating the operation of circulating the cleaning solution for 15 minutes followed by standing for 45 minutes, four times. After that, the RO membrane was rinsed with ion-exchanged treated water, and then the membrane permeate flux was measured by performing a filtration operation using the ion-exchanged treated water as the raw water.

[0067] [Table 1]

[0068] Figure 5 shows the measurement results of the membrane permeation flux corrected to standard conditions (water temperature 25°C, operating pressure 0.6 MPa). In addition to the membrane permeation flux of the RO membrane before and after cleaning, the membrane permeation flux of a new membrane is also shown for reference. Compared to before cleaning, the membrane permeation flux increased in both cleaning 1 and cleaning 2, indicating a cleaning effect. Furthermore, the membrane permeation flux in cleaning 2 was higher than in cleaning 1, suggesting that the cleaning effect could be further enhanced by increasing the cleaning temperature.

[0069] (Example 2) In Example 2, the cleaning effect of the RO membrane by circulating the cleaning solution was evaluated. A portion of the contaminated RO membrane, similar to that in Example 1, was cut out and used for the test. The contaminated RO membrane was the same as in Example 1, using the experimental RO membrane processing apparatus 2a (effective membrane area 60 cm²) shown in Figure 4. 2 The RO membrane was set up, and a cleaning solution containing a cleaning agent was circulated to the primary side of the RO membrane. In Example 2, the cleaning solution used was the same as in Example 1, containing an alkaline agent and a surfactant, and the pH was adjusted to approximately 12. The cleaning solution was circulated for the first 15 minutes, and then left to stand for 4 hours. After standing, a one-pass rinse operation was performed by passing tap water through the primary side of the RO membrane only once.

[0070] Figure 6 shows the measurement results of the membrane permeation flux corrected to standard conditions (water temperature 25°C, operating pressure 0.6 MPa). By continuing the rinsing operation with tap water, the water permeability performance recovered over time. In Example 2, the cleaning effect of the RO membrane was enhanced by allowing sufficient rinsing time after immersion in the cleaning solution.

[0071] (Example 3) In Example 3, based on the results of Examples 1 and 2, a cleaning operation was performed using an actual RO membrane treatment facility. The RO membrane treatment facility was in operation at a food factory (maximum treatment water volume 80 m³). 3 Membrane cleaning was performed using the RO membrane treatment equipment. Figure 7 shows a schematic diagram of the RO membrane treatment equipment. The supplied raw water is pressurized by the raw water pump 1, which consists of a high-pressure pump, and sent to the RO membrane unit 2 (reverse osmosis membrane device). The RO membrane unit 2 has multiple membrane elements housed in vessels arranged in a tree shape. This equipment is equipped with a cleaning liquid return pipe 10 that branches off from the concentrated water pipe 7 and leads to the cleaning liquid tank 3, a cleaning liquid supply pipe 9 that goes from the cleaning liquid tank 3 through the cleaning liquid pump 4 to the inlet side of the RO membrane unit 2, a circulation pipe (circulation line 8) that branches off from the discharge side of the cleaning liquid pump 4 and returns to the cleaning liquid tank 3, and valves V71 to V77 numbered 1 to 7.

[0072] During normal operation, the first valve V71, the sixth valve V76, and the seventh valve V77 were open, and the second valve V72 and the fifth valve V75 were closed, and the reverse osmosis membrane treatment was performed in the normal operation. This RO membrane treatment equipment underwent a cleaning operation because its water permeability (membrane permeation flux) decreased and the amount of treated water decreased. Prior to the cleaning operation, during the normal operation of the reverse osmosis membrane treatment, a predetermined amount of tap water (with free chlorine removed) was supplied to the cleaning solution tank 3, and the cleaning agents used in Examples 1 and 2 were added thereto, and the pH was pre-adjusted to approximately 12. Next, the third valve V73 was closed and the fourth valve V74 was opened, and the cleaning solution pump 4 was operated to circulate the cleaning solution and perform a cleaning solution homogenization and heating operation. At this time, the opening degree of the fourth valve V74 was adjusted to increase the pressure of the cleaning solution pump 4 and raise the temperature of the cleaning solution. Before the circulation operation, the temperature of the cleaning solution was 17°C, but after the circulation operation, the temperature of the cleaning solution rose to 22°C.

[0073] After raising the temperature of the cleaning solution, the first valve V71, the fourth valve V74, the sixth valve V76, and the seventh valve V77 were closed, and the second valve V72, the third valve V73, and the fifth valve V75 were opened, and the cleaning solution was circulated for 15 minutes. Next, the cleaning solution pump 4 was stopped, and the cleaning solution was allowed to stand for 4 hours. After standing, the second valve V72, the fifth valve V75, and the seventh valve V77 were closed, and the first valve V71 and the sixth valve V76 were opened, and raw water was supplied to push out the cleaning solution and discharge it from the RO membrane unit 2. Next, raw water was passed through for 14 hours, and a rinsing operation was performed to complete the cleaning operation. Figure 8 shows the progress of the membrane permeation flux converted to a water temperature of 20°C and a pressure of 1 MPa. From September onward, the membrane permeation flux decreased due to membrane contamination and remained low, but after cleaning, the membrane permeation flux increased, indicating the effectiveness of cleaning. [Explanation of Symbols]

[0074] 1… Raw water pump 2…Reverse osmosis membrane system (RO membrane unit) 3…Cleaning solution tank 4…Cleaning solution pump 5…Raw water supply pipe 6…Permeate water piping 7…Concentrated water piping 8…Circulation line 9… Cleaning fluid supply piping 10… Cleaning fluid return piping 11…Permeate water piping 12…Water supply piping V11, V21, V31, V71... First valve V12, V22, V32, V72... Second valve V13, V23, V33, V73... Third valve V14, V24, V34, V74...the fourth valve V15, V25, V35, V75...the fifth valve V16, V26, V36, V76...the sixth valve V17, V27, V37, V77...the seventh valve 20...Opening adjustment means 21...pH adjustment means 22...Means of notification 31...Temperature measurement means 32...pH measuring means

Claims

1. In a method for cleaning a reverse osmosis membrane apparatus equipped with a reverse osmosis membrane, The concentration of the cleaning solution in the cleaning solution tank that stores the cleaning solution for cleaning the reverse osmosis membrane is adjusted to a concentration suitable for cleaning the reverse osmosis membrane. The cleaning solution is pressurized by a pump, the heat generated by the pump is used to warm the cleaning solution, and the warmed cleaning solution is circulated into the cleaning solution tank via a circulation line connected between the pump and the cleaning solution tank, thereby adjusting the temperature of the cleaning solution in the cleaning solution tank to a temperature suitable for cleaning the reverse osmosis membrane. The cleaning solution, adjusted to the concentration and temperature suitable for the cleaning process of the reverse osmosis membrane, is supplied to the reverse osmosis membrane apparatus using the pump for cleaning. A method for cleaning a reverse osmosis membrane apparatus, including one containing a membrane.

2. The process includes pressurizing raw water with a raw water pump, supplying the pressurized raw water to the reverse osmosis membrane apparatus to obtain permeate and concentrated water through reverse osmosis membrane treatment, and then performing the washing treatment. During the reverse osmosis membrane treatment, the cleaning solution in the cleaning solution tank is heated to a certain temperature or higher by circulating it between the cleaning solution pump connected to the cleaning solution tank and the cleaning solution tank via a circulation line connected between the cleaning solution pump and the cleaning solution tank. In the cleaning process, the cleaning solution, adjusted to the concentration and temperature suitable for cleaning the reverse osmosis membrane, is supplied to the reverse osmosis membrane apparatus via the cleaning solution pump. A method for cleaning a reverse osmosis membrane apparatus according to claim 1, including the following:

3. A first valve connected to a raw water supply pipe that supplies the raw water to the reverse osmosis membrane apparatus, A second valve connected to a cleaning fluid supply pipe that supplies the cleaning fluid to the raw water supply pipe, A third valve connected between the second valve and the cleaning fluid pump, A fourth valve connected to the aforementioned circulation line, A fifth valve is connected between the concentrated water piping that carries the concentrated water flowing out of the reverse osmosis membrane apparatus and the cleaning solution tank, A sixth valve connected to the aforementioned concentrated water piping, A seventh valve connected to a permeate pipe through which permeate water flowing out of the reverse osmosis membrane device flows, This includes controlling the opening and closing of each, When performing the reverse osmosis membrane treatment, the first valve, the sixth valve, and the seventh valve are opened, and the second valve and the fifth valve are closed. When heating the cleaning solution, the third valve is closed and the fourth valve is opened, the cleaning solution pump is operated, the cleaning solution in the cleaning solution tank is circulated through the circulation line, the opening of the fourth valve is adjusted, and the cleaning solution is heated by the heat generated by the cleaning solution pump. When performing the cleaning process, the first valve, the fourth valve, the sixth valve, and the seventh valve are closed, and the second valve, the third valve, and the fifth valve are opened, and the cleaning fluid pump is operated to circulate the cleaning fluid between the reverse osmosis membrane device and the cleaning fluid tank. A method for cleaning a reverse osmosis membrane apparatus according to claim 2, including the following:

4. The method for cleaning a reverse osmosis membrane apparatus according to claim 3, further comprising, when performing the cleaning process, circulating the cleaning solution between the reverse osmosis membrane apparatus and the cleaning solution tank, closing the second valve, the fifth valve, and the seventh valve, opening the first valve and the sixth valve to send the raw water to the reverse osmosis membrane apparatus, and discharging the cleaning solution from the reverse osmosis membrane apparatus.

5. The cleaning solution is supplied to the reverse osmosis membrane apparatus. A method for cleaning a reverse osmosis membrane apparatus according to claim 2, comprising stopping the cleaning solution pump and allowing the cleaning solution to stand in the reverse osmosis membrane apparatus for a certain period of time, and then restarting the operation of the cleaning solution pump.

6. The method for cleaning a reverse osmosis membrane apparatus according to claim 3, further comprising, after the reverse osmosis membrane treatment, reducing the opening of the first valve or the second valve and warming the raw water or cleaning solution supplied to the reverse osmosis membrane apparatus by the heat of the raw water pump.

7. A method for cleaning a reverse osmosis membrane apparatus according to any one of claims 1 to 6, comprising adjusting the pH of the cleaning solution to 10 or higher.

8. A method for cleaning a reverse osmosis membrane apparatus according to any one of claims 1 to 6, comprising adding a surfactant to the cleaning solution.

9. A method for cleaning a reverse osmosis membrane apparatus according to any one of claims 1 to 6, comprising adjusting the pH of the cleaning solution to 2 or less.

10. A cleaning device for a reverse osmosis membrane apparatus, which pressurizes raw water with a raw water pump and brings it into contact with a reverse osmosis membrane to obtain concentrated water and permeate water, A cleaning solution tank for storing a cleaning solution for cleaning the reverse osmosis membrane, A cleaning solution pump pressurizes the cleaning solution and supplies it into the reverse osmosis membrane apparatus, A circulation line is connected between the cleaning fluid pump and the cleaning fluid tank, and while circulating the cleaning fluid between the cleaning fluid pump and the cleaning fluid tank, the heat generated from the cleaning fluid pump warms the cleaning fluid to a temperature suitable for cleaning the reverse osmosis membrane. A supply line that supplies water into the cleaning solution tank so that the cleaning solution in the cleaning solution tank becomes a concentration suitable for cleaning the reverse osmosis membrane, A cleaning liquid piping system supplies the cleaning liquid, adjusted to a concentration and temperature suitable for cleaning the reverse osmosis membrane, to the inlet side of the reverse osmosis membrane apparatus, and returns the cleaning liquid discharged from the reverse osmosis membrane apparatus to the cleaning liquid tank. A cleaning device for a reverse osmosis membrane apparatus.

11. A cleaning device for a reverse osmosis membrane apparatus, which pressurizes raw water with a raw water pump and brings it into contact with a reverse osmosis membrane to obtain concentrated water and permeate water, A cleaning solution tank for storing a cleaning solution for cleaning the reverse osmosis membrane, A cleaning solution pump pressurizes the cleaning solution and supplies it into the reverse osmosis membrane apparatus, A circulation line is connected between the raw water pump and the cleaning solution tank, and while circulating the cleaning solution between the raw water pump and the cleaning solution tank, the heat generated from the raw water pump warms the cleaning solution to a temperature suitable for cleaning the reverse osmosis membrane. A supply line that supplies water into the cleaning solution tank so that the cleaning solution in the cleaning solution tank reaches a concentration suitable for cleaning the reverse osmosis membrane, A cleaning liquid piping system supplies the cleaning liquid, adjusted to a concentration and temperature suitable for cleaning the reverse osmosis membrane, to the inlet side of the reverse osmosis membrane apparatus, and returns the cleaning liquid discharged from the reverse osmosis membrane apparatus to the cleaning liquid tank. A cleaning device for a reverse osmosis membrane apparatus.

12. A first valve connected to a raw water supply pipe that supplies the raw water to the reverse osmosis membrane apparatus, A second valve connected to a cleaning fluid supply pipe that supplies the cleaning fluid to the raw water supply pipe, A third valve connected between the second valve and the cleaning fluid pump, A fourth valve connected to the aforementioned circulation line, A fifth valve is connected between the concentrated water piping that carries the concentrated water flowing out of the reverse osmosis membrane apparatus and the cleaning solution tank, A sixth valve connected to the aforementioned concentrated water piping, A seventh valve connected to a permeate pipe through which permeate water flowing out of the reverse osmosis membrane device flows, Equipped with, When performing reverse osmosis membrane treatment in the reverse osmosis membrane apparatus, the first valve, the sixth valve, and the seventh valve are opened, and the second valve and the fifth valve are closed. When heating the cleaning solution, the third valve is closed and the fourth valve is opened, the cleaning solution pump is operated, the cleaning solution in the cleaning solution tank is circulated through the circulation line, the opening of the fourth valve is adjusted, and the cleaning solution is heated by the heat generated by the cleaning solution pump. When performing the cleaning process, the first valve, the fourth valve, the sixth valve, and the seventh valve are closed, and the second valve, the third valve, and the fifth valve are opened, and the cleaning fluid pump is operated to circulate the cleaning fluid between the reverse osmosis membrane device and the cleaning fluid tank. A cleaning apparatus for a reverse osmosis membrane apparatus according to claim 10, including the following:

13. A pH measuring means for measuring the pH of the cleaning solution in the cleaning solution tank, Based on the measurement results of the pH measuring means, a pH adjusting means supplies acid or alkali into the cleaning solution tank. A cleaning apparatus for a reverse osmosis membrane apparatus according to any one of claims 10 to 12, comprising:

14. A temperature measuring means for measuring the temperature of the cleaning solution in the cleaning solution tank, A notification means capable of notifying when the temperature of the cleaning solution in the cleaning solution tank reaches a temperature suitable for cleaning the reverse osmosis membrane, A cleaning apparatus for a reverse osmosis membrane apparatus according to any one of claims 10 to 12, comprising:

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