Sterilization method for pharmaceutical water production system

Abstract

To inhibit damage of an ultrafilter membrane caused by dryness after a pharmaceutical water production system is sterilized by steam.SOLUTION: In a sterilization method of a pharmaceutical water production system 12 in which processed water sent from a storage tank 16 is filtered by a membrane filtration device 18 including an ultrafilter membrane 18M, the processed water is stored in the tank to turn the tank into a storage state, the processed water is discharged from the membrane filtration device 18, and the membrane filtration device 18 is sterilized with steam. Then, the processed water is sent from the tank maintaining the storage state to the membrane filtration device 18 to be placed in contact with the ultrafilter membrane 18M.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This application relates to a method for sterilizing a pharmaceutical water production system.

Background Art

[0002] When producing pharmaceutical water including water for injection, the water to be treated is filtered by an ultrafiltration membrane (UF membrane) so that the water to be treated can be produced without distillation (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When producing pharmaceutical water including water for injection, in a pharmaceutical water production system using an ultrafiltration membrane, the ultrafiltration membrane may be sterilized by steam. Generally, steam sterilization is applied to metal pipes and metal equipment such as stills. However, the ultrafiltration membrane has lower resistance to temperature compared with metal equipment. Therefore, it has been unclear whether it is possible to directly apply the conventionally performed steam sterilization.

[0005] An object of this application is to provide a method for sterilizing a pharmaceutical water production system capable of performing steam sterilization of an ultrafiltration membrane without deteriorating the ultrafiltration membrane.

Means for Solving the Problems

[0006] When sterilizing a pharmaceutical water production system with steam, if the state where the water to be treated does not come into contact with the ultrafiltration membrane continues after sterilization, the ultrafiltration membrane may dry out and deteriorate. For example, if it is immediately after replacing with a new ultrafiltration membrane, the drying of the ultrafiltration membrane is suppressed by operating the pharmaceutical water production system. However, when steam-sterilizing the ultrafiltration membrane incorporated in the pharmaceutical water production system, in the pharmaceutical water production system after steam sterilization, the time during which the water to be treated does not come into contact with the ultrafiltration membrane may continue.

[0007] As a result of intensive studies, the inventors of the technology of the present disclosure have found that when steam is in contact with the ultrafiltration membrane, the deterioration of the ultrafiltration membrane hardly progresses. However, when the time of contact with air continues in a high-temperature state and a rapid temperature drop due to heat dissipation occurs after the supply of steam stops, the deterioration becomes severe. In particular, in a short time when the ultrafiltration membrane should not originally dry out, deterioration such as a decrease in the strength and separation performance of the ultrafiltration membrane progresses. From this, it has been concluded that the deterioration of the ultrafiltration membrane is irreversible deterioration caused by oxygen in the air, and a solution means capable of performing steam sterilization of the ultrafiltration membrane without deterioration of the ultrafiltration membrane has been obtained.

[0008] A first aspect is a method for sterilizing a pharmaceutical water production system that filters water to be treated sent from a storage tank with a membrane filtration device equipped with an ultrafiltration membrane, wherein the water to be treated is stored in a tank to make the tank in a storage state, the water to be treated is discharged from the membrane filtration device, the membrane filtration device is sterilized with steam, and then the water to be treated is sent from the storage tank that maintains the storage state to the membrane filtration device to bring the water to be treated into contact with the ultrafiltration membrane.

[0009] In the method for sterilizing a pharmaceutical water production system according to the first aspect, the water to be treated is stored in a tank to make the tank in a storage state. This tank may be a storage tank for storing the water to be treated sent to the membrane filtration device, or may be a tank provided separately from this storage tank. Furthermore, this tank may be not only a tank constituting the pharmaceutical water production system but also a tank not constituting the pharmaceutical water production system.

[0010] Then, after discharging the water to be treated from the membrane filtration device and sterilizing the membrane filtration device with steam, the water to be treated is sent from the tank maintaining the storage state to the membrane filtration device and brought into contact with the ultrafiltration membrane. Since the tank is maintained in the storage state where the water to be treated is stored, compared with the configuration in which the water to be treated is stored in a tank where the water to be treated is not stored and then the water to be treated is sent from the tank to the membrane filtration device, the water to be treated can be sent to the membrane filtration device in a short time and brought into contact with the ultrafiltration membrane. Also, by adjusting the temperature of the water to be treated using temperature adjusting means such as a heat exchanger, compared with the configuration where the water to be treated is not stored in the tank, it becomes possible to adjust the temperature drop rate of the membrane filtration device in a short time. Since the time during which the water to be treated does not contact the ultrafiltration membrane after sterilization does not continue, the time during which the ultrafiltration membrane contacts oxygen in the air due to drying also does not continue. That is, it is possible to perform steam sterilization of the ultrafiltration membrane without deteriorating the ultrafiltration membrane.

[0011] Note that, in order to prevent the water to be treated in the membrane filtration device from flowing out to the outside, the end of the pipe leading to the membrane filtration device is made higher than the highest part of the ultrafiltration membrane inside the membrane filtration device, or the pipe leading to the membrane filtration device is sealed with a valve or the like, so that the state in which the water to be treated is in contact with the ultrafiltration membrane can be maintained.

[0012] In a second aspect, in the first aspect, the tank is the storage tank.

[0013] That is, in a pharmaceutical water production system, since the storage tank for storing the water to be treated sent to the membrane filtration device is used as the tank, there is no need to newly provide a tank.

[0014] In a third aspect, in the second aspect, the storage tank is brought into the storage state by discharging the water to be treated from the storage tank, sterilizing the storage tank with steam, and then storing the water to be treated in the storage tank.

[0015] That is, before sterilizing the membrane filtration device with steam, the storage tank can be sterilized with steam and brought into a storage state in which the water to be treated is stored in the storage tank.

[0016] In a fourth aspect, in the second aspect, after sending the water to be treated from the storage tank to the membrane filtration device and bringing the water to be treated into contact with the ultrafiltration membrane, the water to be treated is discharged from the storage tank, the storage tank is sterilized with steam, and then the water to be treated is stored in the storage tank.

[0017] That is, after sterilizing the membrane filtration device with steam, the storage tank can be sterilized with steam, and further, the water to be treated can be stored in the storage tank.

Advantages of the Invention

[0018] In the technology of the present disclosure, it is possible to perform steam sterilization of the ultrafiltration membrane without deteriorating the ultrafiltration membrane.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0020] Hereinafter, the pharmaceutical water production system 12 according to the first embodiment will be described with reference to the drawings. This pharmaceutical water production system 12 is a system for producing pharmaceutical water including water for injection, and is an example of the pharmaceutical water production system of the technology of the present disclosure. The water introduced into the pharmaceutical water production system 12, processed by the pharmaceutical water production system 12, and flowing to the use point 22

[0021] The pharmaceutical water production system 12 of the first embodiment has a steam generator 14, a storage tank 16, a membrane filtration device 18, a pharmaceutical water tank 20, and a use point 22. The water introduced into the pharmaceutical water production system 12, processed by the pharmaceutical water production system 12, and flowing to the use point 22 is the "water to be treated" of the technology of the present disclosure.

[0022] The steam generator 14 is a device that generates superheated steam in the technology of the present disclosure. Superheated steam is steam heated to a temperature exceeding the boiling point. By sending this superheated steam to the storage tank 16 and the membrane filtration device 18, the parts including the storage tank 16 and the membrane filtration device 18 can be sterilized. However, as long as it is possible to sterilize the storage tank 16 and the membrane filtration device 18, the steam is not limited to superheated steam.

[0023] The pretreated water pretreated by the pretreatment device 82 is supplied to the storage tank 16 through the inflow pipe 30. In the pretreatment device 82, pretreatment such as filtration by a filtration device (including filtration by a reverse osmosis device) and ion exchange by an ion exchange device such as an electrodeionization device or an ion exchange resin tower is performed on municipal water, well water, industrial water, tap water, etc. Then, in the storage tank 16, the pretreated water flowing in through the inflow pipe 30 is stored. The pretreated water is the water processed by the pharmaceutical water production system 12 and is included in the water to be treated.

[0024] An on-off valve (not shown) is provided in the inflow pipe 30. By opening this on-off valve, the pretreated water can be introduced into the storage tank 16 as the water to be treated from the pretreatment device 82.

[0025] The storage tank 16 is provided with a pressure sensor 16P, a temperature sensor 16T, a water level sensor 16L, and a conductivity sensor 16C. The pressure sensor 16P detects the pressure inside the storage tank 16. The temperature sensor 16T detects the temperature inside the storage tank 16. The water level sensor 16L detects the water level inside the storage tank 16. The conductivity sensor 16C detects the conductivity of the water to be treated stored in the storage tank 16. Various data detected by these sensors are transmitted to the computer 102 shown in FIG. 2.

[0026] The storage tank 16 and the membrane filtration device 18 are connected by a first water supply pipe 32. In the technology of the present disclosure, the vertical position of the storage tank 16 is set so that the water surface of the storage tank 16 is higher than the upper end of the ultrafiltration membrane 18M inside the membrane filtration device 18 in the vertical direction. A first pump 24 is provided in the first water supply pipe 32. By driving the first pump 24, the water to be treated can be sent from the storage tank 16 to the membrane filtration device 18 through the first water supply pipe 32.

[0027] In the technology of the present disclosure, the membrane filtration device 18 has a hydrophobic ultrafiltration membrane 18M. The inside of the membrane filtration device 18 is partitioned by the ultrafiltration membrane 18M, and the water to be treated flowing into one of the partitioned regions is filtered by the ultrafiltration membrane 18M. Then, the water to be treated that has not passed through the ultrafiltration membrane 18M is discharged to the outside as concentrated water. The water to be treated that has passed through the ultrafiltration membrane 18M is sent to the pharmaceutical water tank 20. As the ultrafiltration membrane 18M, for example, a hollow fiber membrane with a molecular weight cut-off of 6000 can be used, but it is not limited thereto.

[0028] The membrane filtration device 18 is provided with a pressure sensor 18P, a temperature sensor 18T, and a conductivity sensor 18C. The pressure sensor 18P detects the pressure inside the membrane filtration device 18. The temperature sensor 18T detects the temperature inside the membrane filtration device 18. The conductivity sensor 18C detects the conductivity of the water to be treated inside the membrane filtration device 18. Data detected by these sensors are transmitted to the computer 102 shown in FIG. 2.

[0029] In the first water supply pipe 32, discharge pipes 34 branch off from the upstream side and the downstream side of the first pump 24. An on-off valve 36 is provided in each of the discharge pipes 34. By opening at least one of the on-off valves 36, the water to be treated can be discharged from the first water supply pipe 32 to the outside of the pharmaceutical water production system 12. By closing both of the on-off valves 36, the water to be treated can be sent from the storage tank 16 to the membrane filtration device 18 without being discharged.

[0030] An on-off valve 38 is provided in the first water supply pipe 32. In the technology of the present disclosure, the storage tank 16 is provided at a position higher than the membrane filtration device 18 in the vertical direction. Therefore, if the water level in the storage tank 16 is higher than the water level in the membrane filtration device 18, the water to be treated can flow from the storage tank 16 to the membrane filtration device 18 by gravity by opening the on-off valve 38 without driving the first pump 24. By closing the on-off valve 38, the flow of the water to be treated from the storage tank 16 to the membrane filtration device 18 can be blocked.

[0031] The membrane filtration device 18 and the pharmaceutical water tank 20 are connected by a second water supply pipe 46. A discharge pipe 48 branches off from the second water supply pipe 46. An on-off valve 50 is provided in the discharge pipe 48. By opening the on-off valve 50, the water to be treated can be discharged from the second water supply pipe 46 to the outside of the pharmaceutical water production system 12. By closing the on-off valve 50, it is possible to send the water to be treated from the membrane filtration device 18 to the pharmaceutical water tank 20 without discharging it. Note that instead of or in combination with the discharge pipe 48, a configuration may be adopted in which a discharge pipe is provided near the storage tank 16 in the reflux pipe 52 to the storage tank.

[0032] A pressure sensor 20P, a temperature sensor 20T, and a water level sensor 20L are provided in the pharmaceutical water tank 20. The pressure sensor 20P detects the pressure inside the pharmaceutical water tank 20. The temperature sensor 20T detects the temperature inside the pharmaceutical water tank 20. The water level sensor 20L detects the water level inside the pharmaceutical water tank 20. The data detected by these sensors is transmitted to the computer 102 shown in FIG. 2.

[0033] In the second water supply pipe 46, a reflux pipe 52 branches off from a position downstream of the branch portion of the discharge pipe 48. The tip of the reflux pipe 52 is connected to the storage tank 16.

[0034] In the second water supply pipe 46, a on-off valve 54 is provided on the downstream side of the branch portion of the reflux pipe 52. By opening the on-off valve 54, the water to be treated can be sent from the membrane filtration device 18 to the pharmaceutical water tank 20. By closing the on-off valve 54, the flow of the water to be treated from the membrane filtration device 18 to the pharmaceutical water tank 20 can be blocked. Note that the water to be treated sent to the pharmaceutical water tank 20 has been filtered by the membrane filtration device 18 and foreign substances have been removed to such an extent that it can be used as pharmaceutical water.

[0035] The reflux pipe 52 is provided with an on-off valve 56. By opening the on-off valve 56, a flow path for returning the pharmaceutical water from the membrane filtration device 18 to the storage tank 16 is configured. By closing the on-off valve 56, the flow (return flow) of the pharmaceutical water from the membrane filtration device 18 to the storage tank 16 can be blocked.

[0036] In the technology of the present disclosure, the manufactured pharmaceutical water is stored in the pharmaceutical water tank 20. When this pharmaceutical water is not heated, purified water or cold WFI (Water for Injection) is stored in the pharmaceutical water tank 20. On the other hand, when the water to be treated is heated by a heat exchanger (not shown) provided in the pipe from the storage tank 16 to the pharmaceutical water tank 20, for example, the first water supply pipe 32 or the second water supply pipe 46, the pharmaceutical water tank 20 stores, for example, injection water heated in a temperature range of 60°C or higher and 85°C or lower.

[0037] The pharmaceutical water tank 20 is provided with a circulation pipe 60. The circulation pipe 60 is provided with a second pump 26 and a heat exchanger 62. By driving the second pump 26, the pharmaceutical water stored in the pharmaceutical water tank 20 can be discharged outside the pharmaceutical water tank 20 once and then returned (circulated) to the pharmaceutical water tank 20 through the circulation pipe 60.

[0038] The heat exchanger 62 is configured to be supplied with a heat medium from a heat source (not shown). The heat exchanger 62 exchanges heat between this heat medium and the pharmaceutical water flowing through the circulation pipe 60, and raises or maintains the temperature of the pharmaceutical water to a predetermined level or higher. By setting the temperature of the pharmaceutical water to a predetermined level or higher in this way, the pharmaceutical water is maintained in a state where it can be used as injection water.

[0039] In the circulation pipe 60, a supply pipe 64 branches off from the downstream side of the heat exchanger 62. The tip of the supply pipe 64 is connected to the use point 22. An on-off valve 66 is provided in the supply pipe 64. By opening the on-off valve 66, the pharmaceutical water flowing through the circulation pipe 60 can be sent to the use point 22 through the supply pipe 64.

[0040] One end of a steam supply pipe 72 is connected to the steam generator 14. The steam supply pipe 72 branches into three, and the tips (the other ends) of the branched pipes are connected to the storage tank 16, the membrane filtration device 18, and the pharmaceutical water tank 20, respectively. A flow path switching valve (not shown) is provided in the steam supply pipe 72, and the steam generated by the steam generator 14 can be supplied to any one or more of the storage tank 16, the membrane filtration device 18, and the pharmaceutical water tank 20.

[0041] Furthermore, the pharmaceutical water production system 12 has a compressed gas pipe 74. One end of the compressed gas pipe 74 is connected to a compressor 84. The compressed gas pipe 74 branches into three, and the tips (the other ends) of the branched pipes are connected to the storage tank 16, the membrane filtration device 18, and the pharmaceutical water tank 20, respectively. A flow path switching valve (not shown) is provided in the compressed gas pipe 74, and the compressed gas generated by the compressor 84 can be supplied to any one or more of the storage tank 16, the membrane filtration device 18, and the pharmaceutical water tank 20. The compressed gas may be, for example, compressed air or compressed nitrogen gas. Impurities have been removed from these compressed gases to such an extent that there are no problems with the quality of the pharmaceutical water supplied to or produced by the pharmaceutical water production system 12.

[0042] One end of the exhaust pipe 28 is connected to the storage tank 16. The other end of the exhaust pipe 28 is open to the atmosphere. An on-off valve 40 is provided in the exhaust pipe 28. The on-off valve 40 is a so-called freezer valve, such as a hydrophobic filter with a pore diameter of 0.2 μm, which is opened when the pressure on the storage tank 16 side becomes higher than the atmospheric pressure by a predetermined value or more. Thereby, the pressure in the storage tank 16 is kept below a predetermined pressure.

[0043] In the drawings, the pipes through which the steam generated by the steam generator 14 flows are indicated by broken lines. Also, the pipes through which the compressed gas generated by the compressor 84 flows are indicated by one-dot chain lines. Further, the pipes through which the water to be treated flows are indicated by solid lines. However, compressed air may also flow through the pipes through which the treated water flows.

[0044] FIG. 2 shows the internal configuration of the computer 102 that controls the sterilization process of the pharmaceutical water production system 12 in the first embodiment.

[0045] The computer 102 has a processor 104, a memory 106, a storage 108, a display unit 110, an input unit 112, a reception unit 114, and a communication unit 116.

[0046] The storage 108 stores a control program for causing the computer 102 to function as a control device. By this control program being expanded on the memory 106 and further executed by the processor 104, the computer 102 functions as a control device. In the technology disclosed in the present application, the control program includes a sterilization program 70 for performing a sterilization process on the pharmaceutical water production system 12.

[0047] The display unit 110 is, for example, a display and display lamps, etc. The display unit 110 displays the state of the computer 102 and the states of various devices connected to this computer 102.

[0048] The input unit 112, such as a keyboard, a mouse, and a switch, etc., receives various inputs from an operator to the computer 102.

[0049] As will be described later, the reception unit 114 receives an instruction to execute the startup method of the technology disclosed in the present application when the pharmaceutical water production system 12 is started up. Substantially, a part of the input unit 112 can be configured to have the function of the reception unit 114. The display unit 110 may be configured as a touch panel to also serve as the input unit 112 and the reception unit 114.

[0050] The communication unit 116 communicates with, for example, the pressure sensor 16P, the temperature sensor 16T, the water level sensor 16L, the pressure sensor 18P, the temperature sensor 18T, the pressure sensor 20P, the temperature sensor 20T, and the water level sensor 20L, and performs data transmission and reception with these sensors. Also, the communication unit 116 communicates with the first pump 24 and the second pump 26, and performs signal transmission and reception for controlling these pumps. Further, although not shown in FIG. 2, the communication unit 116 performs signal transmission and reception with various valves provided in the pharmaceutical water production system 12, and controls the opening and closing of these valves.

[0051] In the pharmaceutical water production system 12 of the first embodiment, pharmaceutical water is produced by executing the pharmaceutical water production process. When producing pharmaceutical water, first, the pretreated water produced by the pretreatment device 82 is supplied as the water to be treated to the storage tank 16. The water to be treated stored in the storage tank 16 is supplied to the membrane filtration device 18 through the first water supply pipe 32 by driving the first pump 24 with the on-off valve 38 opened. This water to be treated becomes pharmaceutical water by being treated (filtered) by the membrane filtration device 18. A part of the pharmaceutical water is returned to the storage tank 16 by the reflux pipe 52 with the on-off valve 56 opened, and the other part is sent to the pharmaceutical water tank 20 with the on-off valve 54 opened.

[0052] Next, the sterilization method and operation of the pharmaceutical water production system 12 of the first embodiment will be described.

[0053] FIG. 3 shows an example of a flowchart when performing the sterilization method in the pharmaceutical water production system 12 of the first embodiment. In this sterilization method, the sterilization program 70 stored in the storage 108 is expanded on the memory 106 and executed by the processor 104. The sterilization process includes sterilizing the system including the storage tank 16 and the membrane filtration device 18 with steam.

[0054] [Sealing process of membrane filtration device] When executing the sterilization method in the pharmaceutical water production system 12, first, the above-described pharmaceutical water production process is stopped. Then, in step S102, the computer 102 seals the membrane filtration device 18. Specifically, the on-off valve 38 and the on-off valve 56 are closed. Also, the on-off valve 50 and the on-off valve 54 are closed. Thereby, the treated water does not flow out from the membrane filtration device 18, and the state where the treated water is in contact with the ultrafiltration membrane 18M is maintained.

[0055] [Steam sterilization process in storage tank] Next, in step S104, the computer 102 steam-sterilizes the inside of the storage tank 16. Specifically, first, the on-off valve 36 is opened and compressed air is supplied from the compressor 84 to the storage tank 16. Thereby, the treated water remaining in the storage tank 16 is discharged from the discharge pipe 34, and the storage tank 16 is drained. Then, by closing the on-off valve (not shown) of the steam supply pipe 74, the supply of compressed air from the compressor 84 is stopped. Also, the on-off valve 36 is closed. Further, by supplying superheated steam from the steam generator 14 to the storage tank 16, the inside of the storage tank 16 is sterilized. Actually, in the first water supply pipe 32 connected to the storage tank 16, the portion communicating with the storage tank 16 is also sterilized by steam.

[0056] [Cooling and replacement process in storage tank] After the sterilization of the storage tank 16 is completed, in step S106, the computer 102 performs gas replacement while cooling the inside of the storage tank 16. Specifically, the supply of steam from the steam generator 14 to the storage tank 16 is stopped. Then, compressed gas is supplied from the compressor 84 to the storage tank 16 through the compressed gas pipe 74. The inside of the storage tank 16 is cooled by the compressed gas, and the gas inside the storage tank 16 is replaced from steam to compressed gas. The steam inside the storage tank 16 is discharged from the discharge pipe 34. When the cooling inside the storage tank 16 is completed, the on-off valve 36 is closed.

[0057] [Water filling process in the storage tank] Next, in step S108, the computer 102 fills the storage tank 16 with water. Specifically, first, pretreated water is supplied from the pretreatment device 82 to the storage tank through the inflow pipe 30. Then, when the water volume in the storage tank 16 reaches a predetermined water volume, the computer 102 stops the supply of the pretreated water to the storage tank 16. As a result, the storage tank 16 is set in a storage state in which the water to be treated is stored. For the determination of whether the water volume in the storage tank 16 has reached the predetermined water volume, for example, the water level detected by the water level sensor 16L can be used. Also, when the supply flow rate (supply amount per unit time) of the pretreated water to the storage tank 16 is known, it may be determined that the water volume in the storage tank 16 has reached the predetermined water volume when the supply time has reached the predetermined time.

[0058] Note that in the state where the water to be treated is introduced into the storage tank 16 in this way, the on-off valve 40 is open. As a result, the gas inside the storage tank 16 is discharged to the outside from the exhaust pipe 28.

[0059] [Water draining process in the membrane filtration device] Next, in step S110, the computer 102 drains the membrane filtration device 18. Specifically, the on-off valve 50 is opened, and compressed gas is supplied from the compressor 84 to the membrane filtration device 18 through the compressed gas pipe 74. Thereby, the water to be treated in the membrane filtration device 18 is discharged from the discharge pipe 48, and the membrane filtration device 18 is drained. Note that the draining of the membrane filtration device 18 does not have to be after the filling of the storage tank 16 is completed. In other words, it suffices that the filling of the storage tank 16 is completed before bringing the water to be treated into contact with the ultrafiltration membrane 18M by filling the membrane filtration device 18 (described later).

[0060] [Steam sterilization process in the membrane filtration device] Next, in step S112, the computer 102 steam-sterilizes the membrane filtration device 18. Specifically, superheated steam is supplied from the steam generator 14 to the membrane filtration device 18 through the steam supply pipe 72. Thereby, the inside of the membrane filtration device 18 is sterilized. Actually, in the first water supply pipe 32 and the second water supply pipe 46 connected to the membrane filtration device 18, the portions communicating with the membrane filtration device 18 are also sterilized by steam. Note that when a discharge pipe is provided near the storage tank 16 in the reflux pipe 52 instead of or in combination with the discharge pipe 48, this discharge pipe can also be steam-sterilized simultaneously with the steam sterilization of the membrane filtration device 18. In this case, the entire circulation system composed of the storage tank 16, the membrane filtration device 18, and the reflux pipe 52 can be sterilized.

[0061] [Cooling and replacement process in the membrane filtration device] After the sterilization of the membrane filtration device 18 is completed, in step S114, the computer 102 cools the inside of the membrane filtration device 18 and performs gas replacement. Specifically, the supply of steam from the steam generator 14 to the membrane filtration device 18 is stopped. Then, compressed gas is supplied from the compressor 84 into the membrane filtration device 18 through the compressed gas pipe 74. The inside of the membrane filtration device 18 is cooled by the compressed gas, and the gas inside the membrane filtration device 18 is replaced from steam to compressed gas. The steam inside the membrane filtration device 18 is discharged from the discharge pipe 48. When the cooling inside the membrane filtration device 18 is completed, the on-off valve 50 is closed.

[0062] [Water filling process inside the membrane filtration device] Next, in step S116, the computer 102 fills the membrane filtration device 18 with water. Specifically, the on-off valve 38 is opened. The storage tank 16 maintains a storage state in which the water to be treated is stored. If the water level in the storage tank 16 is higher than the water level in the membrane filtration device 18, the water to be treated flows from the storage tank 16 to the membrane filtration device 18 by gravity without driving the first pump 24. That is, since the water to be treated is already stored in the storage tank 16, after the steam sterilization of the membrane filtration device 18, this water to be treated can be immediately flowed into the membrane filtration device 18 to fill the membrane filtration device 18 with water. Since the membrane filtration device 18 is filled with water by gravity, the risk of damage to the ultrafiltration membrane 18M of the membrane filtration device 18 can be reduced.

[0063] Also, if the water filling into the membrane filtration device 18 starts when the temperature inside the membrane filtration device 18 reaches 100 °C or lower, preferably when it reaches a predetermined temperature of 65 °C or higher and 85 °C or lower, the time during which the ultrafiltration membrane 18M inside the membrane filtration device 18 is exposed to compressed gas can be shortened. In this case, the water to be treated stored in the storage tank 16 is heated so that the temperature of the water to be treated stored in the storage tank 16 is approximately the same (within the range of ±10 °C) as the temperature of the water to be treated in the storage tank 16, or a heating device is provided in the first water supply pipe 32 between the storage tank 16 and the membrane filtration device 18 to heat it, so that the heated water to be treated can be supplied into the membrane filtration device 18.

[0064] Furthermore, when this method is used, the time during which the ultrafiltration membrane 18M is exposed to compressed gas can be shortened, and a rapid temperature drop of the ultrafiltration membrane 18M after water filling inside the membrane filtration device 18 can be suppressed. Therefore, suppression of deterioration of the ultrafiltration membrane 18M due to a rapid temperature drop can also be expected.

[0065] Thus, the sterilization of the pharmaceutical water production system 12 is completed.

[0066] When the water quality of the water to be treated in the storage tank 16 and the membrane filtration device 18 reaches the desired water quality, open the on-off valves 38 and 54, and close the on-off valves 36 and 50. Then, by driving the first pump 24, the water to be treated can be sent from the storage tank 16 through the membrane filtration device 18 to the pharmaceutical water tank 20 through the first water supply pipe 32 and the second water supply pipe 46.

[0067] Also, in this state, if the on-off valve 54 is closed and the on-off valve 56 is opened, the liquid to be treated can be circulated from the storage tank 16 through the membrane filtration device 18 back to the storage tank 16 through a part of the first water supply pipe 32, the second water supply pipe 46, and the reflux pipe 52.

[0068] By driving the second pump 26 with the on-off valve 66 closed, the pharmaceutical water stored in the pharmaceutical water tank 20 can be circulated from the pharmaceutical water tank 20 through the circulation pipe 60 back to the pharmaceutical water tank 20. Also, in this state, by opening the on-off valve 66, the pharmaceutical water can be sent from the pharmaceutical water tank 20 to the use point 22 through a part of the circulation pipe 60 and the supply pipe 64. A heat exchanger 62 is provided in the circulation pipe 60, and by heating the pharmaceutical water to a predetermined temperature by the heat exchanger 62, it is also possible to use the pharmaceutical water as injection water.

[0069] As described above, in the sterilization method of the pharmaceutical water production system according to the first embodiment, after sterilizing the storage tank 16 with steam, the storage tank 16 is filled with the water to be treated. Then, after sterilizing the membrane filtration device 18 with steam, the water to be treated already stored in the storage tank 16 is introduced into the membrane filtration device 18. Here, as a comparative example, assume a configuration in which the water to be treated is not stored in the storage tank 16 at the stage when the sterilization of the membrane filtration device 18 is completed. In the configuration of the comparative example, after storing the water to be treated in the storage tank 16, the stored water to be treated is introduced into the membrane filtration device 18, so the time until the water to be treated contacts the ultrafiltration membrane 18M of the membrane filtration device 18 becomes longer. However, in the first embodiment, after sterilizing the storage tank 16 with steam, the water to be treated stored in the storage tank 16 is introduced into the membrane filtration device 18, so the time during which the water to be treated does not contact the ultrafiltration membrane 18M does not continue. Therefore, even when steam sterilization conventionally performed on metal equipment is applied to the ultrafiltration membrane 18M, deterioration of the ultrafiltration membrane 18M caused by the continuous time during which the water to be treated does not contact the ultrafiltration membrane 18M can be suppressed. That is, according to the technology of the present disclosure, a sterilization method for the pharmaceutical water production system 12 capable of performing steam sterilization of the ultrafiltration membrane 18M without deterioration of the ultrafiltration membrane 18M can be obtained.

[0070] Incidentally, in the above description, the water filling in the membrane filtration device 18 is performed using the water to be treated stored in the storage tank 16. However, a tank separate from the storage tank 16 may be provided, and the water filling in the membrane filtration device 18 may be performed using the water to be treated stored in this tank. That is, at the start time of water filling in the membrane filtration device 18, if a tank provided separately from the storage tank 16 is in a state of storing the water to be treated, the water to be treated is sent from this tank into the membrane filtration device 18. Thereby, after sterilizing the storage tank 16 with steam, a method can be realized in which the time during which the water to be treated does not contact the ultrafiltration membrane 18M does not continue. The tank provided separately from the storage tank 16 is not limited to the tanks constituting the pharmaceutical water production system 12, and may be a tank not constituting the pharmaceutical water production system 12. For example, a vehicle equipped with a tank may be prepared, and the tank mounted on this vehicle may be used for the sterilization method of the pharmaceutical water production system of the present disclosure. The storage of the water to be treated in the tank may be performed at the installation site of the pharmaceutical water production system 12.

[0071] Incidentally, after sterilizing the membrane filtration device 18 with steam, in order to suppress the drying of the ultrafiltration membrane, for example, a configuration in which the water to be treated is sent from the storage tank 16 to the membrane filtration device 18 while storing the water to be treated in the storage tank 16 is also conceivable. However, if the water to be treated is sent from the storage tank 16 to the membrane filtration device 18 in a state where a sufficient amount of the water to be treated is not stored in the storage tank 16, air may be mixed into the water to be treated and sent to the membrane filtration device 18. Further, when sending the water to be treated from the storage tank 16 to the membrane filtration device 18, if the water is sent intermittently, the water to be treated may hit the ultrafiltration membrane impactfully due to what is called water hammer, leading to damage to the ultrafiltration membrane. However, in the technology of the present disclosure, since a sufficient amount of the water to be treated is stored in the storage tank 16 and this water to be treated is sent to the membrane filtration device 18, air is not mixed into the water to be treated. Further, by continuously sending the liquid to be treated from the storage tank 16 to the membrane filtration device 18, damage to the ultrafiltration membrane 18M due to so-called water hammer can be suppressed.

[0072] Next, a modification of the first embodiment will be described. In the modification, the same reference numerals are given to the same elements, members, etc. as in the first embodiment, and detailed descriptions thereof are omitted.

[0073] As shown in FIG. 4, in the pharmaceutical water production system 92 of the modification, a circulation pipe 94 branches from the first water supply pipe 32. One end of the circulation pipe 94 (the branch portion from the first water supply pipe 32) is located downstream of the first pump 24 and upstream of the on-off valve 38 in the first water supply pipe 32. The other end of the circulation pipe 94 is connected to the storage tank 16.

[0074] An on-off valve 96 is provided in the circulation pipe 94. By opening the on-off valve 96, it is possible for the water to be treated to flow from the branch portion with the first water supply pipe 32 through the circulation pipe 94 and return to the storage tank 16 (be circulated).

[0075] In the pharmaceutical water production system 92 of the modification configured as described above, even if the water to be treated is not stored in the storage tank 16 up to a predetermined water level, the above-described water hammer can be suppressed and the water to be treated can be sent from the storage tank 16 to the membrane filtration device 18.

[0076] Specifically, with the on-off valve 38 closed and the on-off valve 96 open, the first pump 24 is driven. As a result, a flow is realized in which the water to be treated in the storage tank 16 returns from the branch portion in the first water supply pipe 32 through the circulation pipe 94 to the storage tank 16. In this state, by gradually opening the on-off valve 38, the water to be treated gradually flows from the storage tank 16 to the membrane filtration device 18. Therefore, it is possible to supply the water to be treated to the membrane filtration device 18 and prime the membrane filtration device 18 while suppressing the deterioration of the ultrafiltration membrane 18M due to the so-called water hammer.

[0077] In the second embodiment, by constantly circulating the water to be treated flowing through the first water supply pipe 32 and the circulation pipe 94, it is possible to suppress the retention of the water to be treated in the first water supply pipe 32 and the circulation pipe 94.

[0078] Next, a second embodiment will be described. In the second embodiment, since the overall configuration of the pharmaceutical water production system and the configuration of the computer are the same as those shown in FIGS. 1 and 2 of the first embodiment, the illustration thereof will be omitted. Also in the second embodiment, when executing the sterilization method of the pharmaceutical water production system 12, first, the pharmaceutical water production process is stopped.

[0079] FIG. 5 shows an example of a flowchart when performing the sterilization method of the pharmaceutical water production system of the second embodiment. In this sterilization method, similar to the first embodiment, the sterilization program 70 stored in the storage 108 is expanded on the memory 106 and executed by the processor 104 (see FIG. 2). The sterilization treatment includes sterilizing the system including the storage tank 16 and the membrane filtration device 18 with steam. In the second embodiment, when executing the sterilization method of the pharmaceutical water production system 12, a storage state in which the water to be treated is stored is maintained in the storage tank 16.

[0080] [Water draining process in the membrane filtration device] The computer 102 drains the water in the membrane filtration device 18 in step S142. Specifically, similar to the first embodiment, the on-off valve 50 is opened, and compressed gas is supplied from the compressor 84 to the membrane filtration device 18 through the compressed gas pipe 74. Thereby, the water to be treated in the membrane filtration device 18 is discharged from the discharge pipe 48, and the membrane filtration device 18 is drained.

[0081] [Steam sterilization process in the membrane filtration device] Next, the computer 102 sterilizes the membrane filtration device 18 in step S144. By supplying superheated steam from the steam generator 14 to the membrane filtration device 18 through the steam supply pipe 72, the inside of the membrane filtration device 18 is sterilized. In the first water supply pipe 32 and the second water supply pipe 46 connected to the membrane filtration device 18, the portions communicating with the membrane filtration device 18 are also sterilized with steam.

[0082] [Cooling and replacement process in the membrane filtration device] After the sterilization of the membrane filtration device 18 is completed, in step S146, the computer 102 performs gas replacement while cooling the inside of the membrane filtration device 18. That is, the supply of steam from the steam generator 14 to the membrane filtration device 18 is stopped, and compressed gas is supplied from the compressor 84 into the membrane filtration device 18 through the compressed gas pipe 74. As a result, the inside of the membrane filtration device 18 is cooled, and the gas inside the membrane filtration device 18 is replaced from steam to compressed gas. The steam inside the membrane filtration device 18 is discharged from the discharge pipe 48. When the cooling inside the membrane filtration device 18 is completed, the on-off valve 50 is closed.

[0083] [Water filling process inside the membrane filtration device] Next, in step S148, the computer 102 fills the inside of the membrane filtration device 18 with water. Specifically, the on-off valve 38 is opened. If the water level in the storage tank 16 is higher than the water level in the membrane filtration device 18, the water to be treated flows from the storage tank 16 to the membrane filtration device 18 by gravity without driving the first pump 24. That is, since the water to be treated is already stored in the storage tank 16, after the steam sterilization of the membrane filtration device 18, it is possible to immediately flow this water to be treated into the membrane filtration device 18 to fill the membrane filtration device 18 with water.

[0084] [Sealing process of the membrane filtration device] Then, in step S150, the computer 102 seals the membrane filtration device 18. The on-off valve 38, the on-off valve 56, the on-off valve 50, and the on-off valve 54 are closed.

[0085] [Steam sterilization process inside the storage tank] Next, in step S152, the computer 102 steam-sterilizes the inside of the storage tank 16. That is, by opening the on-off valve 36 and supplying compressed air from the compressor 84 to the storage tank 16, the treated water in the storage tank 16 is discharged from the discharge pipe 34, and the storage tank 16 is drained. After that, the supply of compressed air from the compressor 84 is stopped, and the on-off valve 36 is also closed. Then, superheated steam is supplied from the steam generator 14 to the storage tank 16. In the first water supply pipe 32 connected to the storage tank 16, the portion communicating with the storage tank 16 is also sterilized by steam.

[0086] [Cooling and replacement process in the storage tank] After the sterilization of the storage tank 16 is completed, in step S154, the computer 102 performs gas replacement while cooling the inside of the storage tank 16. That is, the supply of steam from the steam generator 14 to the storage tank 16 is stopped, and compressed gas is supplied from the compressor 84 to the storage tank 16 through the compressed gas pipe 74. The inside of the storage tank 16 is cooled by the compressed gas, and the gas inside the storage tank 16 is replaced from steam to compressed gas. The steam inside the storage tank 16 is discharged from the discharge pipe 34. When the cooling inside the storage tank 16 is completed, the on-off valve 36 is closed.

[0087] [Water filling process in the storage tank] Next, in step S156, the computer 102 fills the inside of the storage tank 16 with water. That is, pretreated water is supplied from the pretreatment device 82 to the storage tank through the inflow pipe 30. Then, when the water volume in the storage tank 16 reaches a predetermined water volume, the computer 102 stops the supply of pretreated water to the storage tank 16. For the determination of whether the water volume in the storage tank 16 has reached the predetermined water volume, for example, similar to the first embodiment, the water level detected by the water level sensor 16L can be used. Also, when the supply flow rate of the pretreated water to the storage tank 16 (the supply amount per unit time) is known, it may be determined that the water volume in the storage tank 16 has reached the predetermined water volume when the supply time reaches the predetermined time.

[0088] When the water to be treated is being introduced into the storage tank 16, the on-off valve 40 is in the open state, and the gas in the storage tank 16 is discharged to the outside through the exhaust pipe 28.

[0089] Thereafter, in the same manner as in the first embodiment, the water quality of the water to be treated in the storage tank 16 and in the membrane filtration device 18 is confirmed. When the water quality of the water to be treated has reached the desired water quality, the pharmaceutical water stored in the pharmaceutical water tank 20 can be circulated through the circulation pipe 60 and sent to the use point 22.

[0090] In addition, also in the second embodiment, a tank different from the storage tank 16 may be provided, and the priming in the membrane filtration device 18 may be performed using the water to be treated stored in this tank.

[0091] In the above, when the inside of the storage tank 16 is being steam-sterilized, for the various pipes connected to the storage tank 16, since steam flows through the portions communicating with the storage tank 16, they can be steam-sterilized. Similarly, when the inside of the membrane filtration device 18 is being steam-sterilized, for the various pipes connected to the membrane filtration device 18, the portions communicating with the membrane filtration device 18 can be steam-sterilized. For example, when the inside of the membrane filtration device 18 is being steam-sterilized and the on-off valve 56 is opened, steam flows through the reflux pipe 52 via a part of the second water supply pipe 46. That is, in conjunction with the steam sterilization inside the membrane filtration device 18, a part of the second water supply pipe 46 and the reflux pipe 52 can also be steam-sterilized.

[0092] In the technology of the present disclosure, temperature adjustment means such as a heat exchanger may be provided in the tank (which may be the storage tank 16 or a tank provided separately from the storage tank 16) or the first water supply pipe 32. Thereby, the temperature of the water to be treated sent from the tank into the membrane filtration device 18 can be adjusted to a desired temperature. For example, compared with a configuration in which no water to be treated is stored in the tank, in a configuration in which temperature adjustment means is provided in the tank or the first water supply pipe 32, it is possible to adjust the temperature drop rate inside the membrane filtration device 18 in a short time.

[0093] In the above, as a pharmaceutical water production system to which the sterilization method in the technology of the present disclosure is applied, a pharmaceutical water production system was exemplified, but the pharmaceutical water production system is not limited to the pharmaceutical water production system. For example, it may be applied to a cleaning water production system for producing cleaning water for various devices, a food water production system for producing raw material water for food, a chemical water production system for chemical experiments and analysis, and the like.

Example

[0094] The technology of the present disclosure will be specifically described by way of examples and in comparison with comparative examples.

[0095] In the examples and comparative examples, the pharmaceutical water production system of the first embodiment is used, and the steam sterilization of the storage tank 16 and the membrane filtration device 18 is performed under the conditions shown in Table 1 below. And the degree of deterioration of the ultrafiltration membrane 18M in these cases is evaluated. In the evaluation, the tensile elongation retention rate of the chemical fiber filament yarn test method defined in JIS-L1013 was used. Also, the steam temperature was measured at the discharge pipe 48.

[0096]

Table 1

[0097] The tensile elongation retention rate in Table 1 is one of the indexes indicating the degree of deterioration of the ultrafiltration membrane 18M. For example, when the ultrafiltration membrane 18M is not deteriorated, this value is 100%.

[0098] As shown in this Table 1, in the comparative example, at the stage where the number of steam sterilizations reached 10 times, the tensile elongation retention rate of the ultrafiltration membrane 18M decreased by about 70%. This is because in the method of the comparative example, it takes about 30 minutes to store the water to be treated in the storage tank 16 up to a predetermined amount. During that time, the ultrafiltration membrane 18M dries, the water permeability decreases, the elongation at break decreases, and the strength of the ultrafiltration membrane 18M decreases. On the other hand, in the example, even at the stage where the number of steam sterilizations reached 50 times, there is no change in the tensile elongation retention rate of the ultrafiltration membrane 18M, and it can be seen that the deterioration of the ultrafiltration membrane 18M is suppressed.

Description of Symbols

[0099] 12 Pharmaceutical Water Production System 14 Steam Generator 16 Storage Tank 16C Conductivity Sensor 16L Water Level Sensor 16P Pressure Sensor 16T Temperature Sensor 18 Membrane Filtration Device 18C Conductivity Sensor 18M Ultrafiltration Membrane 18P Pressure Sensor 18T Temperature Sensor 20 Pharmaceutical Water Tank 20L Water Level Sensor 20P Pressure Sensor 20T Temperature Sensor 22 Use Point 24 First Pump 26 Second Pump 28 Exhaust Pipe 30 Inflow Pipe 32 On - Off Valve 32 First Water Supply Pipe 34 Discharge Pipe 36 On - Off Valve 38 On - Off Valve 40 On - Off Valve 46 Second Water Supply Pipe 48 Discharge Pipe 50 On - Off Valve 52 Return Pipe 54 On - Off Valve 56 On - Off Valve 60 Circulation Pipe 62 Heat Exchanger 64 Supply Pipe 66 On - Off Valve 70 Sterilization Program 72 Steam Supply Pipe 74 Compressed Gas Pipe 74 Steam Supply Pipe 82 Pretreatment Device 84 Compressor 92 Pharmaceutical Water Production System 94 Circulation pipe 96 On-off valve 102 Computer

Claims

1. A method for sterilizing a pharmaceutical water production system that filters treated water sent from a storage tank through a membrane filtration device equipped with an ultrafiltration membrane, comprising: Storing the treated water in the storage tank to keep the storage tank in a storage state; After discharging the treated water from the membrane filtration device and sterilizing the membrane filtration device with steam, when the temperature inside the membrane filtration device reaches 100°C or lower, sending the treated water from the storage tank that is maintaining the storage state to the ultrafiltration membrane by gravity and bringing the treated water into contact with the ultrafiltration membrane; A method for sterilizing a pharmaceutical water production system.

2. A method for sterilizing a pharmaceutical water production system that filters treated water sent from a storage tank through a membrane filtration device equipped with an ultrafiltration membrane, comprising: Storing the treated water in the storage tank to keep the storage tank in a storage state; Closing the on-off valve provided in the water supply pipe that sends the treated water from the storage tank to the membrane filtration device, and circulating the treated water through a circulation pipe that branches from the storage tank side of the on-off valve in the water supply pipe and returns the treated water to the storage tank; After discharging the treated water from the membrane filtration device and sterilizing the membrane filtration device with steam, when the temperature inside the membrane filtration device reaches 100°C or lower, gradually opening the on-off valve in a state where the flow of the treated water in the storage tank returning to the storage tank through the circulation pipe is realized, so that the treated water gradually flows from the storage tank to the membrane filtration device and the treated water is brought into contact with the ultrafiltration membrane; A method for sterilizing a pharmaceutical water production system.

3. The step of putting the storage tank in the storage state is performed by discharging the treated water from the storage tank, sterilizing the storage tank with steam, and then storing the treated water in the storage tank; The method for sterilizing a pharmaceutical water production system according to Claim 1 or Claim 2.

4. After sending the treated water from the storage tank to the membrane filtration device and bringing the treated water into contact with the ultrafiltration membrane, Discharging the treated water from the storage tank, sterilizing the storage tank with steam, and then storing the treated water in the storage tank; The method for sterilizing a pharmaceutical water production system according to Claim 1 or Claim 2.

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