JP5572563B2 - Hot water disinfection method of nanofiltration membrane - Google Patents

Description

  The present invention relates to a method for hot water disinfection of a nanofiltration membrane in a purified water production apparatus for producing purified water used for medical use, particularly for artificial dialysis and the like.

As a dialysis solution used in artificial dialysis, a solution obtained by diluting a stock solution of dialysis solution with high-purity purified water is used. This purified water for artificial dialysis is required not to contain divalent cations such as calcium and iron, chlorine, bacteria, impurities and the like.
For this reason, purified water for artificial dialysis is treated with a reverse osmosis membrane module (also called RO module) after raw water such as tap water is softened with a water softening device (pretreatment device) and residual chlorine is removed with activated carbon. Manufactured by removing bacteria, impurities, etc. by filtration.

FIG. 2 is a schematic configuration diagram showing an example of a conventional purified water production apparatus for producing purified water used for artificial dialysis and the like.
This purified water production apparatus contains a raw water tank 10 for storing raw water supplied from a tap water, an ion exchange resin for softening raw water sent from the raw water tank 10, and activated carbon for removing residual chlorine in the raw water. Pre-treatment device 11, reverse osmosis membrane modules 12 and 12 arranged in parallel to obtain purified water by filtering softened raw water through a reverse osmosis membrane, purified water tank 13 for storing purified water, and purification An ultraviolet lamp 14 for sterilizing purified water in the water tank 13 and a chemical solution tank 15 for storing a chemical solution for cleaning and disinfecting the reverse osmosis membrane module 12 and the purified water tank 13 are provided.

  Moreover, this purified water production apparatus has one end connected to the raw water tank 10 and the other end connected to the pretreatment device 11, and a raw water supply line provided with a motorized valve 20 and a raw water pump 30 on the downstream side thereof. 40, one end connected to the pretreatment device 11, the other end connected to the reverse osmosis membrane modules 12, 12, and a soft water transfer line 41 provided with a motorized valve 21 and a pressure pump 31 on the downstream side thereof. One end is connected to the reverse osmosis membrane module 12, 12, the other end is connected to the purified water tank 13, and a purified water transfer line 42 provided with a check valve 22, 22 in the middle, and one end is a purified water tank. 13, a water feed pump 33 in the middle and a purified water feed line 43 provided with an electric valve 23 on the downstream side, and one end connected to the reverse osmosis membrane modules 12 and 12, and a flow rate adjusting valve 24 and Than this Electric valve 25 and a concentrated water discharge line 44 provided in the flow side.

  Further, in this purified water production apparatus, one end branches from between the flow rate adjustment valve 24 and the electric valve 25 of the concentrated water discharge line 44, and the other end of the purified water transfer line between the electric valve 21 and the pressurizing pump 31. 41, a concentrated water return line 45 provided with a motorized valve 26 and a check valve 27 downstream thereof, and one end from between the water supply pump 33 and the motorized valve 23 of the purified water supply line 43. The purified water circulation line 46 branched and the other end connected to the purified water tank 13, and one end branched from between the water supply pump 33 and the motor operated valve 23 of the purified water supply line 43, and the motor operated valve 28 was provided in the middle. Purified water discharge line 47, one end connected to the chemical tank 15, the other end connected to the soft water transfer line 41 between the motor-operated valve 21 and the pressurizing pump 31, and a chemical liquid supply provided with the motor-operated valve 29 in the middle Line 48 and these motorized valves Flow control valve, and a control unit for controlling them (not shown) electrically connected to each pump.

  The reverse osmosis membrane module 12 folds the reverse osmosis membrane 50 in a state where a water collecting pipe 52 having a plurality of water collecting holes 51 formed in the center of the reverse osmosis membrane 50, as shown in FIG. The three sides of the reverse osmosis membrane 50 that overlap each other with the liquid-permeable support fiber 53 sandwiched between the reverse osmosis membranes 50 are bonded, and the water collecting pipe 52 with the mesh spacer 54 superimposed on the double reverse osmosis membrane 50. A double reverse osmosis membrane 50 is wound in a columnar shape around the center to form a reverse osmosis membrane element 55, and the reverse osmosis membrane element 55 is accommodated in a cylindrical casing 56.

  In the reverse osmosis membrane module 12, raw water is introduced into a raw water inlet 57 formed on one end face of the reverse osmosis membrane element 55 and flows through a flow path formed by a mesh spacer 54, during which part of the raw water is Then, it passes through the reverse osmosis membrane 50 to become purified water, is led to the water collecting pipe 52 through the flow path formed by the liquid-permeable support fibers 53, and is discharged from the permeated water outlet 58 at the end of the water collecting pipe 52. On the other hand, the raw water that has not passed through the reverse osmosis membrane 50 becomes concentrated water and is discharged from the concentrated water outlet 59 formed on the other end face of the reverse osmosis membrane element 55.

  By the way, in recent years, in the above-described purified water production apparatus, in order to suppress the generation of bacteria, endothermic substances such as exothermic substances due to retention of water in the apparatus, ion exchange provided in the preceding stage of the reverse osmosis membrane module 12 described above. Instead of the pretreatment device 11 using a resin, a purified water production device provided with a nanofiltration membrane module has been proposed (see, for example, Patent Document 1).

  Moreover, in the conventional purified water manufacturing apparatus mentioned above, it is comprised so that disinfection of the purified water tank 13 and various flow paths is possible by flowing a chemical | medical solution. However, when disinfecting with chemicals, only the parts that are in direct contact with the chemicals are disinfected. Otherwise, bacteria and the like may grow, and there is a risk of placing a burden on the reverse osmosis membrane module. Then, what is disinfected by circulating hot water to a reverse osmosis membrane module is proposed (for example, refer patent document 2).

JP 2004-033947 A JP-A-11-333266

  However, in the conventional purified water production apparatus described above, only the reverse osmosis membrane module is subjected to hot water disinfection, so that the previous nanofiltration membrane module is not sufficiently disinfected, and bacteria leaked from the nanofiltration membrane module or In some cases, endotoxin or the like flows into the primary side of the reverse osmosis membrane module and places a burden.

  Therefore, for example, a method of connecting a hot water circulation pipe to the primary side of the nanofiltration membrane module and simultaneously disinfecting the nanofiltration membrane module and the reverse osmosis membrane module can be considered. Even when only one of the membrane modules needs to be sterilized, hot water must be circulated through all the paths, and a large amount of hot water is needed to perform hot water sterilization in places where it is not necessary. As a result, energy consumption increases unnecessarily.

  Therefore, the present invention provides a hot water disinfection method for a nanofiltration membrane that can suppress an increase in energy consumption during the hotwater disinfection of the nanofiltration membrane module.

In order to solve the above-described problems, the invention described in claim 1 includes a water softening means (for example, the nanofiltration membrane module 61 in the embodiment) for softening raw water with a nanofiltration membrane using polyamide as a material. Purifying means (for example, the reverse osmosis membrane module 12 in the embodiment) for obtaining purified water by filtering the softened raw water through a reverse osmosis membrane (for example, the reverse osmosis membrane 50 in the embodiment), and the purified water Storage means (for example, purified water tank 13 in the embodiment), heating means (for example, heater 17 in the embodiment) for heating purified water stored in the storage means, and water softening means provided upstream, and an activated carbon filter activated carbon is accommodated for removing residual chlorine in the raw water (e.g., activated charcoal filter 60 in the embodiment), precision of said storing means Return line for returning water to the upstream side of the water softening means (e.g., hot water supply line 77 in the embodiment) and the storage means of the purified water upstream of supplying hot water supply line of the activated charcoal filter ( For example, the hot water supply line 76) in the embodiment is heated by the heating means, and returned to the upstream side of the water softening means or the activated carbon filter by the return line or the hot water supply line , and at least the water softening is performed. A second hot water discharge line (for example, hot water discharge line 92 in the embodiment) for discharging hot water that is the purified water that has passed through the means, the return line , the hot water supply line, and the second hot water. switchable control unit opening and closing state of the discharge line (e.g., control unit 16 in the embodiment) heat Luna Roh filtration membrane put between, the purified water manufacturing device provided with In the disinfection method, the purified water stored in the storage means is returned from the upstream side of the water softening means through the return line and passed through the water softening means by an operation signal from the control unit. At the same time as the purified water is discharged through the second hot water discharge line, the heating means raises the temperature of the purified water to a predetermined temperature set at a heating rate of 5 ° C./min or less and heats the nanowater. and曝the filtration membrane to the hot water, in the case of simultaneous hot water disinfecting said water softening means and the activated carbon filter, by the operation signal from the control unit, the heat from the purified water that has been savings in the storing means Purified water is circulated from the upstream side of the activated carbon filter through a water supply line, and purified water that has passed through the activated carbon filter and the water softening means is discharged by the second hot water discharge line. Simultaneously with discharging, the heating means raises the purified water to a predetermined temperature set in advance at a rate of 5 ° C./min or less and heats the activated carbon filter and the nanofiltration membrane to the hot water. It is characterized by exposure .
In addition, the purified water production apparatus has a concentrated water discharge line (for example, the concentrated water discharge line 44 in the embodiment) for discharging hot water that is the purified water that has passed through the water softening means and the purification means sequentially. Furthermore, it is preferable that it is provided.
Further, the purified water producing apparatus is heated by the heating means, returned to the upstream side of the activated carbon filter by the hot water supply line, and discharges hot water that is the purified water that has passed through the activated carbon filter. It is preferable to further include a hot water discharge line (for example, the hot water discharge line 90 in the embodiment).

According to the invention described in claim 1, since the purified water heated by the heating means can be supplied to the primary side of the water softening means provided with the nanofiltration membrane via the return line, the water softening means alone is provided. Hot water disinfection can be performed, and thus there is an effect that the consumption of hot water can be suppressed and energy consumption can be reduced.
In addition, the purified water stored in the storage means can be recirculated from the upstream side through the return line by the operation signal from the control unit, and the purified water can be heated by the heating means. Since it can be exposed to water, there is an effect that it is possible to prevent the reverse osmosis membrane from being burdened by bacteria, endotoxin and the like leaking from the water softening means.
In addition, since the temperature can be raised to a predetermined temperature at a rate of 5 ° C./min or less, a sudden temperature change can be suppressed, so that the polyamide that constitutes the water softening means is made of a material with relatively low heat resistance. Even if it is a case, there exists an effect which can suppress deterioration of a water softening means.

It is a schematic block diagram which shows an example of the purified water manufacturing apparatus of this invention. It is a schematic block diagram which shows an example of the conventional purified water manufacturing apparatus. It is a perspective view and a partial sectional view showing an example of a reverse osmosis membrane module.

Hereinafter, the purified water manufacturing apparatus of this invention is demonstrated using drawing.
FIG. 1 is a schematic configuration diagram showing an example of the purified water production apparatus of the present invention.
This purified water production apparatus includes a raw water tank 10 that stores raw water supplied from a water supply, an activated carbon filter 60 that contains activated carbon that removes residual chlorine in raw water sent from the raw water tank 10, and a nanofiltration membrane element. The nanofiltration membrane module 61 (water softening means) containing water and the reverse osmosis membrane modules 12 and 12 (purification means) arranged in parallel to obtain purified water by filtering the softened raw water with a reverse osmosis membrane And a purified water tank 13 (storage means) for storing purified water, and an ultraviolet lamp 14 for sterilizing the purified water in the purified water tank 13.

  In the purified water production apparatus shown in FIG. 1, one end is connected to the raw water tank 10, the other end is connected to the activated carbon filter 60, and the raw water pump 30 is provided on the way and the raw water pump 30 is provided downstream thereof. A supply line 40, one end of the raw water transfer line 70 connected to the activated carbon filter 60 and the other end connected to the nanofiltration membrane module 61, one end connected to the nanofiltration membrane module 61, and the other end connected to the reverse osmosis membrane module 12 , 12, a soft water transfer line 41 provided with a motorized valve 21 and a pressure pump 31 downstream thereof, one end connected to the reverse osmosis membrane modules 12, 12 and the other end to a purified water tank 13, a purified water transfer line 42 provided with check valves 22 and 22 in the middle, and one end connected to the purified water tank 13, and a water feed pump 33 and a motorized valve 2 downstream from this. And a concentrated water discharge line 44 in which one end is connected to the reverse osmosis membrane modules 12 and 12 and a flow rate adjusting valve 24 and a motorized valve 25 are provided downstream thereof. One end branches from between the flow rate adjustment valve 24 and the motor-operated valve 25 of the concentrated water discharge line 44, the other end is connected to the soft water transfer line 41 between the motor-operated valve 21 and the pressurizing pump 31, and the motor-operated valve is in the middle. 26 and a concentrated water return line 45 provided with a check valve 27 on the downstream side thereof, and one end branches from the downstream side of the motorized valve 25 of the concentrated water discharge line 44 and the other end is connected to the raw water tank 10. And a concentrated water return line 71 provided with an electric valve 80 in the middle.

  Furthermore, the purified water production apparatus has one end connected to the nanofiltration membrane module 61 and a concentrated water discharge line 72 provided with a flow rate adjusting valve 81 in the middle, and one end than the flow rate adjusting valve 81 of the concentrated water discharge line 72. Branched from the downstream side, the other end is connected to the raw water supply line 40 between the motor-operated valve 20 and the raw water pump 30, and a concentrated water return line 73 provided with a check valve 82 in the middle, and one end of the purified water supply water The purified water circulation line 46 branched from between the water pump 33 and the electric valve 23 in the line 43 and the other end connected to the purified water tank 13, and the water pump 33 and the electric valve 23 in the purified water supply line 43 at one end. A purified water discharge line 47 branched from the middle and provided with a motor-operated valve 28 on the way, and a control unit 16 that electrically controls the motor-operated valve, the flow rate adjusting valve, and each pump and controls them. ing.

  Here, the soft water transfer line 41 includes a first flow path 41 a for flowing raw water to the raw water inlets 57 and 57 of the reverse osmosis membrane modules 12 and 12 between the pressurization pump 31 and the reverse osmosis membrane modules 12 and 12. The reverse osmosis membrane modules 12 and 12 branch to the second flow path 41b through which the raw water flows to the concentrated water outlets 59 and 59, and a switching valve 84 is provided at the branch point of these flow paths. Further, the concentrated water discharge line 44 is a first channel for flowing concentrated water discharged from the concentrated water outlets 59 and 59 of the reverse osmosis membrane modules 12 and 12 between the reverse osmosis membrane modules 12 and 12 and the flow rate adjusting valve 24. Of the reverse osmosis membrane modules 12 and 12, and a second flow path 44b through which the concentrated water discharged from the raw water inlets 57 and 57 of the reverse osmosis membrane modules 12 and 12 flows. Is provided. In addition, a common pipe is used for the first flow path 41a and the second flow path 44b in the vicinity of the raw water inlet 57, and for the second flow path 41b and the first flow path 44a in the vicinity of the concentrated water outlet 59, Common piping is used.

  By the way, the purified water tank 13 described above is provided with a heater 17 for heating the purified water in the purified water tank 13, and the heater 17 is configured to be able to heat the purified water in the purified water tank 13. And the hot water circulation line 75 for circulating the heated hot water to the predetermined location in an apparatus is connected to the purified water tank 13. FIG.

  Hot water supply lines 76, 77, and 78 are branched and connected to the hot water circulation line 75. The hot water supply line 76 is joined and connected to the raw water supply line 40 on the upstream side of the activated carbon filter 60, and an electric valve 88 for opening and closing the hot water supply line 76 is interposed in the middle. The hot water supply line 77 is joined and connected to the raw water transfer line 70 between the activated carbon filter 60 and the nanofiltration membrane module 61, and an electric valve 87 for opening and closing the hot water supply line 77 is interposed in the middle. . The hot water supply line 78 is joined and connected to the soft water transfer line 41 between the nanofiltration membrane module 61 and the reverse osmosis membrane module 12, and an electric valve 86 for opening and closing the hot water supply line 78 is interposed in the middle. ing.

  A hot water discharge line 90 for discharging hot water is further branched and connected to the raw water transfer line 70 between the activated carbon filter 60 and the nanofiltration membrane module 61. The hot water discharge line 90 is joined and connected to a main drain line 100 that collects various waste water, and a discharge valve 91 that opens and closes the hot water discharge line 90 is interposed in the middle of the hot water discharge line 90. Similarly, a hot water discharge line 92 for discharging hot water is branched and connected to the soft water transfer line 41 between the nanofiltration membrane module 61 and the reverse osmosis membrane module 12. Similar to the hot water discharge line 90, the hot water discharge line 92 is joined and connected to the main drainage line 100, and a discharge valve 93 for opening and closing the hot water discharge line 92 is interposed in the middle.

  A raw water transfer line 94 is branched and connected to the raw water supply line 40. This raw water transfer line 94 is joined and connected to the main drainage line 100, and an electric valve 89 for opening and closing the raw water transfer line 94 is interposed in the middle. By opening the electric valve 89, raw water can flow into the main drainage line 100 and the drainage temperature can be lowered.

  As the reverse osmosis membrane module 12, a so-called spiral-type reverse osmosis unit in which a cylindrical reverse osmosis membrane element 55 in which a reverse osmosis membrane 50 is wound around a water collecting pipe 52 as shown in FIG. Osmotic membrane modules are usually used. The reverse osmosis membrane module in the present invention is not limited to this spiral type reverse osmosis membrane module, and can separate raw water into purified water that has permeated the reverse osmosis membrane and concentrated water that does not permeate the reverse osmosis membrane. Any one can be used.

  Moreover, although the two reverse osmosis membrane modules 12 are used in parallel in the example of FIG. 1, the number according to the required amount of water should just be used. The reverse osmosis membrane 50 may be a reverse osmosis membrane usually used in a purified water production apparatus, and is not particularly limited. Examples of the material include polyamide, polysulfone, cellulose acetate, polyacrylonitrile and the like.

  The nanofiltration membrane module 61 is a module having the same structure as the reverse osmosis membrane module 12 shown in FIG. 3, and a cylindrical nanofiltration membrane element in which a nanofiltration membrane is wound around a water collection pipe is formed in a cylindrical casing. The raw water introduced from the raw water inlet is separated into soft water that has passed through the nanofiltration membrane and concentrated water that has not passed through the nanofiltration membrane.

Here, a nanofiltration membrane (also referred to as an NF membrane or a microfilter) has an intermediate pore diameter between an ultrafiltration membrane (UF membrane) and a reverse osmosis membrane (RO membrane), and charges the membrane material surface. It refers to the membrane that has the more recent IUPAC definition {Journal of Membrane
According to “Membrane and membrane process terminology (1996 IUPAC recommended)” described in Science, 120, 149-159 (1996)}, nanofiltration membranes are “pressures at which particles and macromolecules of a size smaller than 2 nm are blocked. "Drive membrane separation process" (By the way, the microfiltration membrane (MF membrane) is larger than 0.1 μm, and the ultrafiltration membrane (UF membrane) is a membrane capable of blocking the range of 0.1 μm to 2 nm. ). In other words, the nanofiltration membrane combines the separation by pores (size separation) and the separation effect by the electrical interaction between the charge on the surface of the membrane and the ionic components in the solute, and the inherent blocking performance and permeation performance of the membrane. Is shown.

In the present invention, a nanofiltration membrane using polyamide as a material (hereinafter referred to as a polyamide-based nanofiltration membrane) is used. Polyamide-based nanofiltration membranes have a negative fixed charge on the membrane material surface, so they are divalent or higher cations, especially calcium ions, compared to cellulose acetate-based, polysulfone-based, and polyacrylonitrile-based nanofiltration membranes. It has a high ability to remove hardness components such as magnesium ions and is ideal for softening raw water.
In addition, since the polyamide-based nanofiltration membrane has less retention of raw water than an ion exchange resin, bacteria hardly propagate.

  Moreover, since the polyamide-based nanofiltration membrane can block particles and polymers having a size smaller than 2 nm, endotoxin can be removed. In addition, the polyamide nanofiltration membrane has a higher flow rate, a wider usable pH range and temperature range, higher endotoxin removal ability, and higher chemical resistance than cellulose acetate, which is a general nanofiltration membrane.

  The high-pressure pump used for the raw water pump 30, the pressure pump 31, and the water pump 33 is not particularly limited as long as it is normally used in a purified water production apparatus. For example, a multistage centrifugal pump, a plunger pump Etc. can be used.

  The control unit 16 is roughly composed of a processing unit (not shown), an interface unit, and a calendar timer, respectively, and starts supplying raw water to the activated carbon filter 60, the nanofiltration membrane module 61 and the reverse osmosis membrane module 12, and to these. Control of stopping the supply of raw water and starting the discharge of purified water is possible, and these controls can be performed at an arbitrary date and time set in the calendar timer.

The calendar timer includes a clock unit that manages date and time, and a storage unit that stores an operation schedule of the purified water production apparatus, and can transmit an electrical signal at a set date and time stored in the storage unit. Has been.
The interface unit electrically connects all valves, pumps, and processing units provided in each line.
The processing unit controls the opening and closing of valves provided in each line and the start and stop of the pump operation based on an electric signal from the calendar timer and an operation signal input to the processing unit.

The processing unit may be realized by dedicated hardware, and the processing unit is configured by a memory and a central processing unit (CPU), and a program for realizing the function of the processing unit is provided. The function may be realized by loading it into a memory and executing it.
In addition, an input device, a display device, and the like are connected to the control unit 16 as peripheral devices. Here, the input device refers to an input device such as a display touch panel, a switch panel, or a keyboard, and the display device refers to a CRT or a liquid crystal display device.

  Moreover, the opening / closing operation | movement with the motor operated valves 86-88 and the discharge valves 91 and 93 is controlled according to the control command of the control part 16 mentioned above. By controlling the opening of these motorized valves 86 to 88 and the discharge valves 91 and 93, it is possible to circulate hot water individually for the activated carbon filter 60, the nanofiltration membrane module 61, and the reverse osmosis membrane module. . A drainage temperature sensor (not shown) for measuring the drainage temperature of the main drainage line 100 is further connected to the control unit 16. Based on the measurement result of the waste water temperature sensor, the control unit 16 sets the motor operated valve 89 of the raw water transfer line 94 to maintain the temperature of the waste water flowing through the main drain line 100 at a predetermined temperature (for example, 50 ° C.) or less. Opening and closing control is performed to adjust the mixing ratio of the raw water into the main drain line 100.

  Further, the above-described heater 17 is connected to the control unit 16. The controller 16 performs drive control of the heater 17 based on the output of a temperature sensor (not shown) that measures the temperature of purified water in the purified water tank 13 and adjusts the temperature of purified water in the purified water tank 13. Here, when the hot water is circulated by the control unit 16, the temperature of the purified water is controlled to about 60 to 95 ° C. In addition, although the case where the purified water temperature was monitored by the control part 16 and the heater 17 was controlled was demonstrated, the control method of purified water temperature is not restricted to said control method.

  Moreover, the control part 16 calculates | requires the equivalent disinfection time which converted the disinfection time in the predetermined predetermined water temperature (for example, 80 degreeC) into the present purified water temperature, and carries out circulation control of hot water only for this equivalent disinfection time. In this case, the lower the current purified water temperature, the longer the equivalent disinfection time, and the higher the current purified water temperature, the shorter the equivalent disinfection time.

  The display device connected to the control unit 16 can display the above-described equivalent disinfection time. The display of the equivalent disinfection time allows the user to monitor the hot water disinfection time, that is, the equivalent disinfection time.

  The components that make up each line through which the hot water is passed have a heat resistance of at least 90 ° C. For example, the piping part is made of a metal having a relatively high thermal conductivity such as stainless steel. doing. Moreover, the activated carbon filter 60, the reverse osmosis membrane module 12, and the nanofiltration membrane module 61 employ heat resistant specifications. By configuring in this way, each line, the activated carbon filter 60, the reverse osmosis membrane module 12 and the nanofiltration membrane module 61 are heated by hot water. Heat disinfection of the part is possible by heat conduction. For the sake of illustration, the control unit 16 is connected to only some of the motor-operated valves in FIG. 1, but is connected to all valves that can be electronically controlled and to the drive circuits of all pumps.

Next, the manufacturing method of the purified water using this purified water manufacturing apparatus is demonstrated.
At the time of producing purified water, the motorized valve 28 of the purified water discharge line 47, the motorized valve 83 of the purified water return line 74, and the motorized valve 29 of the chemical solution supply line 48 are closed, and the other motorized valves are opened. At the start of purified water production, in the soft water transfer line 41, the first flow path 41a is selected by the switching valve 84, and in the concentrated water discharge line 44, the first flow path 44a is selected by the switching valve 85. .

  The raw water supplied from the raw water tank 10 through the raw water supply line 40 is boosted by the raw water pump 30 and then passed through the activated carbon filter 60. The raw water from which the residual chlorine in the raw water has been removed by the activated carbon filter 60 is supplied to the nanofiltration membrane module 61 through the raw water transfer line 70. A part of the raw water supplied to the nanofiltration membrane module 61 permeates the nanofiltration membrane and is softened. On the other hand, the remaining raw water that has not permeated the nanofiltration membrane becomes concentrated water, and a part of the concentrated water is returned to the raw water supply line 40 through the concentrated water return line 73 branched from the concentrated water discharge line 72 and used as raw water. The remaining concentrated water is reused and discharged out of the apparatus through the concentrated water discharge line 72. At this time, the raw water pressure in the nanofiltration membrane module 61 is adjusted by the flow rate adjustment valve 81.

  The raw water softened by the nanofiltration membrane module 61 is pressurized by the pressurization pump 31 of the soft water transfer line 41 and then supplied to the reverse osmosis membrane modules 12 and 12 through the first flow path 41a. A portion of the raw water supplied to the reverse osmosis membrane module 12 permeates the reverse osmosis membrane to become purified water, and is stored in the purified water tank 13 through the purified water transfer line 42. On the other hand, the remaining raw water that did not permeate the reverse osmosis membrane becomes concentrated water, and part of the concentrated water is returned to the soft water transfer line 41 through the concentrated water return line 45 branched from the concentrated water discharge line 44 and softened. Some concentrated water is returned to the raw water tank 10 through the concentrated water return line 71 branched from the concentrated water discharge line 44 and reused as raw water, and the remaining concentrated water is concentrated water. It is discharged out of the apparatus through the discharge line 44. At this time, the raw water pressure in the reverse osmosis membrane module 12 is adjusted by the flow rate adjustment valve 24.

The purified water stored in the purified water tank 13 is fed out of the apparatus from the purified water feed line 43 by driving the water feed pump 33 and used as dilution water for artificial dialysis.
The purified water stored in the purified water tank 13 is taken out from the purified water supply line 43 by the water pump 33 that is always driven, and then returned to the purified water tank 13 through the purified water circulation line 46. , Constantly in a fluid state. Furthermore, the purified water stored in the purified water tank 13 is always sterilized by the ultraviolet lamp 14.

  Further, the switching valve 84 and the switching valve 85 are switched at regular intervals stored in the calendar timer of the control unit or by a switching operation of the user, the second flow path 41b is selected as the soft water transfer line 41, and the concentrated water It is also possible to select the second flow path 44b as the discharge line 44 and switch the direction of introduction of the raw water into the reverse osmosis membrane module 12 and the outlet of the concentrated water from the reverse osmosis membrane module 12.

Next, the stop time of the purified water production apparatus will be described.
On the basis of a stop signal from the calendar timer of the control unit 16 or a user's stop operation in which the date and time when purified water is not used, such as night and holidays, the control unit 16 stops the operation of the raw water pump 30 and supplies raw water. The motorized valve 20 in the line 40, the motorized valve 21 in the soft water transfer line 41, the motorized valve 23 in the purified water supply line 43, and the motorized valve 25 in the concentrated water discharge line 44 are closed to stop the production of purified water.

  At the same time, the control unit 16 opens the electric valve 86 of the hot water supply line 78. Thereby, the purified water stored in the purified water tank 13 is taken out from the purified water supply line 43 by the water supply pump 34 and then returned to the soft water transfer line 41 through the hot water circulation line 75 and the hot water supply line 78. Is done.

  The purified water returned to the soft water transfer line 41 is supplied to the reverse osmosis membrane modules 12 and 12 through the first channel 41a (or the second channel 41b). A part of the purified water supplied to the reverse osmosis membrane module 12 passes through the reverse osmosis membrane and is sent to the purified water tank 13 through the purified water transfer line 42. On the other hand, the remaining purified water that has not permeated through the reverse osmosis membrane is returned to the soft water transfer line 41 through the concentrated water return line 45 branched from the concentrated water discharge line 44, and again into the reverse osmosis membrane modules 12, 12. Supplied.

  Thus, when the purified water production apparatus is stopped, the purified water in the purified water tank 13 is sent in the order of the water feed pump 34 and the reverse osmosis membrane module 12 and returned to the purified water tank 13 again. That is, the purified water is continuously circulated in the order of the purified water tank 13 -the water pump 34 -the reverse osmosis membrane module 12 -the purified water tank 13.

Next, hot water circulation at the time of disinfection of the purified water production apparatus will be described.
The control unit 16 performs hot water circulation for disinfecting the apparatus when a predetermined time has elapsed after maintenance of the activated carbon filter 60, the nanofiltration membrane module 61, and the reverse osmosis membrane module 12. Here, the activated carbon filter 60, the nanofiltration membrane module 61, and the reverse osmosis membrane module 12 are set in advance with a predetermined time for individually disinfecting. When the preset predetermined time has elapsed, the control unit 16 heats the purified water in the purified water tank 13 with the heater 17 to form hot water, and the hot water is converted into the activated carbon filter 60 and the nanofiltration membrane module, respectively. 61 and the reverse osmosis membrane module 12 are individually passed.

When passing hot water through the nanofiltration membrane module 61, the nanofiltration membrane control unit 16 opens the electric valve 87 of the hot water supply line 77 and discharge valve of the hot water discharge line 92 simultaneously with the start of disinfection. 93 is opened, the water pump 34 of the hot water circulation line 75 is driven, and at the same time, heating of the purified water in the purified water tank 13 by the heater 17 is started. At this time, the motor-operated valves 86 and 88 are preferably maintained in a closed state. Accordingly, the hot water sequentially flows through the purified water tank 13, the hot water circulation line 75, the hot water supply line 77, the raw water transfer line 70, the nanofiltration membrane module 61, the hot water discharge line 92, and the main drain line 100. .
At this time, the heater 17 is heated to a predetermined temperature at 5 ° C./min or less, so that even if a polyamide material constituting the nanofiltration membrane is made of a material having low heat resistance, the heater 17 It is preferable because the deterioration of the filtration membrane can be prevented.

In addition, when hot water is passed through the reverse osmosis membrane module 12, the control unit 16 opens the electric valve 87 of the hot water supply line 77 simultaneously with the start of disinfection, and the discharge valve 93 of the hot water discharge line 92. Is opened, the water pump 34 of the hot water circulation line 75 is driven, and at the same time, the purified water in the purified water tank 13 is heated by the heater 17. At this time, the motor-operated valves 87 and 88 are kept closed. Accordingly, the hot water is supplied from the purified water tank 13, the hot water circulation line 75, the hot water supply line 78, the soft water transfer line 41, the first flow path 41a or the second flow path 41b, the reverse osmosis membrane module 12, the first The first flow path 44a or the second flow path 44b, the concentrated water discharge line 44, and the main drainage line 100 are sequentially passed.
At this time, even when the heater 17 is heated to a predetermined temperature at a rate of 5 ° C./min or less, even if the polyamide material constituting the nanofiltration membrane is made of a material having low heat resistance. The nanofiltration membrane can be prevented from being deteriorated, which is preferable.

When hot water is passed through the activated carbon filter 60, the controller 16 detects that the purified water in the purified water tank 13 has been sufficiently heated to become hot water at a predetermined temperature, and the electric power of the hot water supply line 76 is increased. It is preferable to open the valve 88 and open the discharge valve 91 of the hot water discharge line 90 to drive the water supply pump 34 of the hot water circulation line 75. Unlike the nanofiltration membrane module 61 and the reverse osmosis membrane module 12, when washing activated carbon with high heat resistance, heating the purified water to a predetermined temperature and then starting refluxing allows a shorter time with a smaller amount of purified water. This is because the cleaning can be completed.
At this time, the motor-operated valves 86 and 87 are kept closed. Thus, the hot water sequentially flows through the purified water tank 13, the hot water circulation line 75, the hot water supply line 76, the raw water supply line 40, the activated carbon filter 60, the hot water discharge line 90, and the main drain line 100.

  When hot water is passed through the nanofiltration membrane module 61, the controller 16 detects that the purified water in the purified water tank 13 has been sufficiently heated to become hot water at a predetermined temperature, and then supplies the hot water supply line 77. And the discharge valve 93 of the hot water discharge line 92 is opened to drive the water supply pump 34 of the hot water circulation line 75. At this time, the motor operated valves 86 and 88 are kept closed. Accordingly, the hot water sequentially flows through the purified water tank 13, the hot water circulation line 75, the hot water supply line 77, the raw water transfer line 70, the nanofiltration membrane module 61, the hot water discharge line 92, and the main drain line 100. .

  When hot water is passed through the reverse osmosis membrane module 12, the controller 16 detects that the purified water in the purified water tank 13 has been sufficiently heated to become hot water at a predetermined temperature, and then the hot water supply line 78. The electric valve 86 is opened to drive the water supply pump 34 of the hot water circulation line 75. At this time, the motor-operated valves 87 and 88 are kept closed. Accordingly, the hot water is supplied from the purified water tank 13, the hot water circulation line 75, the hot water supply line 78, the soft water transfer line 41, the first flow path 41a or the second flow path 41b, the reverse osmosis membrane module 12, the first The first flow path 44a or the second flow path 44b, the concentrated water discharge line 44, and the main drainage line 100 are sequentially passed.

  Here, a part of the hot water flowing through the reverse osmosis membrane module 12 is filtered and stored in the purified water tank 13 as purified water via the purified water transfer line 42. In addition, although the case where the hot water which passed the activated carbon filter 60, the nanofiltration membrane module 61, and the reverse osmosis membrane module 12 was drained through the main drainage line 100 was demonstrated, it returns to the purified water tank 13 and the raw | natural water tank 10 And may be reused.

  In addition, when the time for performing disinfection between adjacent ones of the activated carbon filter 60, the nanofiltration membrane module 61, and the reverse osmosis membrane module 12 is close, the control unit 16 allows hot water to flow at the same time. It may be. As an example of this water flow, for example, when the activated carbon filter 60 and the nanofiltration membrane module 61 are close in disinfection time, the electric valve 88 of the hot water supply line 76 is opened and the discharge valve 93 of the hot water discharge line 92 is opened. It opens and the water pump 34 is driven. Thereby, the hot water sequentially flows through the hot water circulation line 75, the hot water supply line 76, the raw water supply line 40, the activated carbon filter 60, the raw water transfer line 70, the nanofiltration membrane module 61, and the hot water discharge line 92. The activated carbon filter 60 and the nanofiltration membrane module 61 are simultaneously sterilized with hot water. Similarly, when the disinfection time of the nanofiltration membrane module 61 and the reverse osmosis membrane module is close, and when all the disinfection times of the activated carbon filter 60, the nanofiltration membrane module 61 and the reverse osmosis membrane module 12 are close, disinfection The motorized valves 86 to 88 connected to the most upstream side of the target can be opened to allow hot water to flow through a plurality of sterilization targets at the same time.

  In the purified water production apparatus as described above, hot water, which is purified water heated by the heater 17 of the purified water tank 13, is supplied to the primary side of the nanofiltration membrane module 61 via the hot water supply line 77. Since the hot water passing through the nanofiltration membrane module 61 can be discharged by the hot water discharge line 92, the nanofiltration membrane module 61 itself can be disinfected with hot water, and thus the amount of hot water used can be reduced. It can suppress and can reduce energy consumption.

  Further, by disinfecting the nanofiltration membrane module 61 with hot water, it is possible to suppress a burden on the reverse osmosis membrane module 12 due to bacteria, endotoxin, etc. leaking from the nanofiltration membrane module 61.

  Furthermore, since hot water can be supplied to the activated carbon filter 60 provided on the upstream side of the nanofiltration membrane module 61 via the hot water supply line 76, the heat of the activated carbon filter 60 is suppressed while suppressing an increase in energy consumption. Water disinfection can be performed and the burden on the nanofiltration membrane module 61 can be reduced.

  And since the nanofiltration membrane module 61 provided with the polyamide-type nanofiltration membrane is used as a water softening means instead of the pretreatment apparatus provided with the conventional ion exchange resin, the residence of raw water decreases and bacteria are It is difficult to reproduce and endotoxin in raw water can be removed. In addition, since the raw water is softened by the nanofiltration membrane module 61, the ion exchange resin and the regenerated salt tank are unnecessary, and accordingly, the management of the regeneration time of the ion exchange resin, the preparation of the drug, the regeneration operation of the ion exchange resin, etc. Therefore, the maintenance and management of the apparatus becomes easy, and the apparatus can be downsized. In addition, since the nanofiltration membrane module 61 removes endotoxin, raw bacteria, and impurities in the raw water, the burden on the reverse osmosis membrane module 12 is reduced, and the frequency of chemical washing of the reverse osmosis membrane module 12 can be reduced. it can.

  The purified water production apparatus further includes a return line (hot water circulation line 75) for returning purified water from the purified water tank 13 to the upstream side of the reverse osmosis membrane module 12 and the pressure pump 31. Therefore, the purified water can be circulated in the apparatus when the purified water production apparatus is stopped. Thereby, even when the purified water production apparatus is stopped, stagnant water may be generated in the pressurizing pump 30, the reverse osmosis membrane module 12, the purified water tank 13, the water pump 34, and the lines connecting them. No bacterial growth can be suppressed.

  In this purified water production apparatus, the first flow path 41a for flowing the raw water supplied to the reverse osmosis membrane module 12 to the raw water inlet 57 and the raw water supplied to the reverse osmosis membrane module 12 to the concentrated water outlet 59, and a switching valve 84 that switches between the first flow path 41a and the second flow path 41b, the direction of introduction of raw water into the reverse osmosis membrane module 12 is provided. It is possible to switch as appropriate. As a result, the raw water flows evenly through the entire flow path formed by the mesh spacer 54 in the reverse osmosis membrane element 55 on the concentrated water outlet 59 side, and the drift and residence on the concentrated water outlet 59 side are reduced, thereby suppressing bacterial growth. It is done.

  The purified water production apparatus of the present invention is not limited to the example shown in the drawing, but in addition to the purification means (reverse osmosis membrane module) for obtaining purified water by filtering raw water through a reverse osmosis membrane, the following (i ) To (iii), (i) water softening means for softening raw water with a nanofiltration membrane using polyamide as a material; (ii) storage means for storing purified water; A return line to be returned upstream and a temporary storage means for temporarily storing purified water returned in the middle of the return line; (iii) supplying raw water to the raw water inlet of the reverse osmosis membrane module and taking out the concentrated water from the concentrated water outlet The first flow path, the second flow path for supplying the raw water to the concentrated water outlet of the reverse osmosis membrane module and taking out the concentrated water from the raw water inlet, and the switching means for switching between the first flow path and the second flow path , Comprising at least one of the components What is necessary is just a purified water production apparatus to be equipped.

12 Reverse osmosis membrane module (purification means)
13 Purified water tank (storage means)
16 Control part 17 Heater (heating means)
40 Raw water supply line 44 Concentrated water discharge line (first drainage line)
50 Reverse osmosis membrane 60 Activated carbon filter (adsorbent)
61 Nanofiltration membrane module (softening means)
78 Hot water supply line (first return line)
77 Hot water supply line (second return line)
90 Hot water discharge line (third drainage line)
92 Hot water discharge line (second drainage line)

Claims (3)

Water softening means for softening raw water with a nanofiltration membrane using polyamide as a material;
Purification means for obtaining purified water by filtering the softened raw water through a reverse osmosis membrane;
Storage means for storing the purified water;
Heating means for heating purified water stored in the storage means;
An activated carbon filter provided on the upstream side of the water softening means and containing activated carbon for removing residual chlorine in raw water;
A return line for returning the purified water of the storage means to the upstream side of the water softening means;
A hot water supply line for supplying purified water of the storage means to the upstream side of the activated carbon filter;
Heated by the heating means, returned to the upstream side of the water softening means or the activated carbon filter by the return line or hot water supply line, and discharges at least hot water that is the purified water that has passed through the water softening means. A second hot water discharge line;
A control unit capable of switching an open / close state of the return line , the hot water supply line, and the second hot water discharge line;
A Luna Roh hydrothermal sterilization method of the filtration membrane put in purified water production apparatus provided with,
In accordance with an operation signal from the control unit, the purified water stored in the storage unit is returned from the upstream side of the water softening unit through the return line, and the purified water that has passed through the water softening unit is returned to the second side. Simultaneously with the discharge through the hot water discharge line, the heating means heats the purified water to a predetermined temperature set in advance at a rate of temperature increase of 5 ° C./min. and曝to water,
When the activated carbon filter and the water softening means are simultaneously disinfected with hot water, the activated carbon filter supplies purified water from the purified water stored in the storage means through the hot water supply line according to an operation signal from the control unit. The purified water that has been refluxed from the upstream side and passed through the activated carbon filter and the water softening means is discharged by the second hot water discharge line, and at the same time, the purified water is heated at a rate of 5 ° C./min or less by the heating means. A hot water disinfection method for a nanofiltration membrane , wherein the activated carbon filter and the nanofiltration membrane are exposed to the hot water by heating to a predetermined temperature set in advance and heating . The heat of the nanofiltration membrane according to claim 1, wherein the purified water production apparatus further includes a concentrated water discharge line that discharges hot water that is the purified water that has passed through the water softening means and the purification means in order. Water disinfection method. The purified water production apparatus is heated by the heating means, returned to the upstream side of the activated carbon filter by the hot water supply line, and discharged with the hot water that is the purified water that has passed through the activated carbon filter. The method for hot water disinfection of a nanofiltration membrane according to claim 1 or 2, further comprising a discharge line.

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