JP2009028600A - Purified water production equipment - Google Patents

Abstract

[PROBLEMS] To reduce the retention of raw water and purified water in the apparatus, to suppress the growth of bacteria and the generation of endotoxin, to maintain the apparatus easily and to be stable even if the temperature of the raw water changes. It aims at the purified water manufacturing apparatus which can ensure the production amount of purified water.
SOLUTION: Temperature adjusting means for adjusting temperature of raw water, softening means for softening raw water with a nanofiltration membrane, and purification means for obtaining purified water by filtering the softened raw water with a reverse osmosis membrane. Purified water production apparatus characterized by performing. The temperature control means for adjusting the temperature of the raw water, the purification means for obtaining purified water by filtering the raw water through a reverse osmosis membrane, the storage means for storing the purified water, and the purified water in the storage means are returned to the upstream side of the purification means. A purified water production apparatus comprising: a return line; and temporary storage means for temporarily storing purified water returned in the middle of the return line.
[Selection] Figure 1

Description

  The present invention relates to a purified water production apparatus for producing purified water used for medical use, in particular, artificial dialysis and the like.

As the dialysate used in the artificial dialysis, a solution obtained by diluting a stock solution of dialysate 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.
Therefore, purified water for artificial dialysis is softened from tap water and other raw water with a water softening device (pre-treatment device), residual chlorine is removed with activated carbon, etc., and bacteria are then used with a reverse osmosis membrane (RO membrane) module. It is manufactured by removing impurities 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 the raw water sent from the raw water tank 10 and activated carbon for removing residual chlorine in the raw water. A pretreatment device 11 and reverse osmosis membrane modules 12 and 12 arranged in parallel to obtain purified water by filtering softened raw water through a reverse osmosis membrane are provided. Further, a purified water tank 13 for storing purified water, an ultraviolet lamp 14 for sterilizing purified water in the purified water tank 13, and a chemical solution tank for storing chemical solutions for cleaning and disinfecting the reverse osmosis membrane module 12 and the purified water tank 13 15.

  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. It comprises. Further, 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 A concentrated water discharge line 44 provided with the motor-operated valve 25 on the downstream side is provided.

  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. And a purified water discharge line 47. Further, one end is connected to the chemical solution tank 15, the other end is connected to the soft water transfer line 41 between the motor-operated valve 21 and the pressurizing pump 31, and a chemical solution supply line 48 provided with the motor-operated valve 29 on the way, and these An electric valve, a flow rate adjusting valve, and a control unit (not shown) that is electrically connected to each pump and performs these controls are roughly configured.

  In this purified water production apparatus, since chlorine does not remain in the purified water, there is a possibility that bacteria will propagate in the purified water stored in the purified water tank 13. Therefore, the purified water in the purified water tank 13 is always flowed by the purified water circulation line 46 or the purified water tank 13 is sterilized so that the purified water in the purified water tank 13 does not stay and the environment in which bacteria are likely to propagate. An ultraviolet lamp 14 is provided. Further, the chemical solution is periodically passed from the chemical solution tank 15 to the reverse osmosis membrane module 12 and the purified water tank 13 to clean and disinfect the reverse osmosis membrane module 12 and the purified water tank 13.

  By the way, in recent years, the contamination of purified water by exothermic factors such as endotoxin generated from bacterial dead bodies has been regarded as important. This endotoxin remains in the purified water even if the purified water is sterilized by the ultraviolet lamp 14. In order to suppress the generation of endotoxin, it is necessary to keep the sterility of the purified water tank 13 constantly at a high level. At the same time, in the pretreatment device 11 and the reverse osmosis membrane module 12, it is necessary to cope with bacterial growth and endotoxin generation.

For example, in the pretreatment device 11, stagnation of raw water is likely to occur due to the ion exchange resin, and bacteria may propagate. In the reverse osmosis membrane module 12, due to the structure, there is a possibility that a drift is likely to occur in the module, or that the osmosis tends to stay and bacteria may propagate. Further, when purified water is not manufactured such as at night, stagnant water may be generated in the reverse osmosis membrane module 12, the purified water tank 13 and the surrounding piping (line), and bacteria may propagate.
In order to prevent the growth of bacteria in the accumulated water, it is effective to drain the accumulated water when purified water is not produced, but the performance of the ion exchange resin and reverse osmosis membrane module decreases when dried. There is a case.

When the purified water is not manufactured, the purified water production device that does not retain the purified water in the reverse osmosis membrane module is equipped with a return line to return the purified water discharged from the reverse osmosis membrane module to the raw water tank, and reverse osmosis with the raw water tank An apparatus that circulates raw water and purified water between membrane modules is proposed in Patent Document 1.
However, in this purified water production apparatus, while the raw water and purified water are circulated, the raw water passes through the pretreatment device, so that the load on the pretreatment device increases and the life of the ion exchange resin is shortened. There was a problem of becoming.

  In addition, as a purified water production device that does not retain purified water in the reverse osmosis membrane module and the purified water tank when purified water is not produced, the purified water in the purified water tank is supplied to the suction side of the pressure pump upstream of the reverse osmosis membrane module. Patent Document 2 proposes an apparatus that circulates purified water between a reverse osmosis membrane module and a purified water tank by providing a return line for returning to the water. In addition, as purified water production equipment that does not retain purified water in the reverse osmosis membrane module when purified water is not produced, the purified water discharged from the reverse osmosis membrane module is supplied to the suction pump suction side upstream of the reverse osmosis membrane module. An apparatus that circulates purified water of a reverse osmosis membrane module by providing a return line that is returned to is proposed in Patent Document 3.

  However, in the devices of Patent Literature 2 and Patent Literature 3, during normal operation, the raw water flows back through the return line due to valve malfunction or the like, and the raw water is the secondary side of the purified water tank or reverse osmosis membrane module (the purified water side). ) And contaminated purified water.

  Moreover, in the conventional purified water manufacturing apparatus, when the capacity | capacitance of the ion exchange resin of the pretreatment apparatus 11 fell, it was necessary to reproduce | regenerate ion exchange resin. In order to regenerate the ion exchange resin, it is necessary to separately provide a regenerated salt tank 16 for supplying the pretreatment device 11 with a chemical for regenerating the ion exchange resin. Preparation of a medicine, regeneration operation of an ion exchange resin, and the like are required, and there is a problem that a great deal of labor is required for maintenance of the pretreatment device 11.

The purified water production apparatus of Patent Document 4 has been proposed as a purified water production apparatus that can reduce the maintenance work of the pretreatment apparatus and that does not retain purified water in the reverse osmosis membrane module and the purified water tank. In the purified water production apparatus of Patent Document 4, the nanofiltration membrane module is provided upstream of the reverse osmosis membrane module, thereby softening the raw water and preventing the inflow of bacteria and endotoxin downstream, and simultaneously purifying the storage means. A return line for returning the water to the upstream side of the purification means and a temporary storage means for temporarily storing the purified water returned in the middle of the return line are provided, and the purified water of the reverse osmosis membrane module is used when purified water is not manufactured. Circulation suppresses bacterial growth and endotoxin generation due to the accumulation of stagnant water.
JP 2000-5300 A JP 2001-969 A JP 2001-293471 A JP 2004-8958 A

However, the nanofiltration membrane and the reverse osmosis membrane used in the device of Patent Document 4 have a reduced permeate flow rate (flux) of 2 to 3% due to a decrease in water temperature of 1 ° C. due to the nature of the membrane. There was a problem that the production amount was easily affected by changes in water temperature. In particular, in winter when the water temperature decreases, the amount of purified water produced tends to decrease, and the amount of purified water produced is difficult to be secured stably.
The present invention has been made in view of the above-mentioned problems, and the retention of raw water and purified water in the apparatus is reduced, bacterial growth and endotoxin generation are suppressed, and at the same time, maintenance of the apparatus is easy, And it aims at the purified water manufacturing apparatus which can ensure the production amount of the purified water stable even if the water temperature of raw | natural water changes.

That is, the purified water production apparatus of the present invention employs the following configuration.
(1) A temperature adjusting means for adjusting the temperature of the raw water, a water softening means for softening the raw water with a nanofiltration membrane, and a purification means for obtaining purified water by filtering the softened raw water with a reverse osmosis membrane. It is characterized by that.
(2) The purified water production apparatus according to (1), wherein the temperature adjusting means is provided in a raw water tank that stores raw water.
(3) Temperature adjusting means for adjusting the temperature of the raw water, softening means for softening the raw water with a nanofiltration membrane, purification means for obtaining purified water by filtering the softened raw water with a reverse osmosis membrane, and purified water A storage means for storing the water, a return line for returning purified water of the storage means to the upstream side of the purification means, and a temporary storage means for temporarily storing purified water returned in the middle of the return line, Purified water production equipment.
(4) The purified water production apparatus according to (3), wherein the temperature adjusting means is provided in a raw water tank that stores raw water.

  According to the purified water production apparatus of the present invention, retention of raw water in the apparatus can be reduced, bacterial growth and endotoxin generation can be suppressed, and maintenance and management of water softening means can be easily performed. Even if the water temperature changes, a stable amount of purified water can be secured.

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 contains temperature adjusting means 90 for adjusting the temperature of raw water supplied from a tap, etc., raw water tank 10 for storing raw water, and activated carbon for removing residual chlorine in the raw water sent from the raw water tank 10. The activated carbon filter 60, the nanofiltration membrane module 61 (water softening means) containing the nanofiltration membrane elements, and the purified water obtained by filtering the softened raw water through a reverse osmosis membrane are arranged in parallel. Reverse osmosis membrane modules 12, 12 (purification means), purified water tank 13 (storage means) for storing purified water, ultraviolet lamp 14 for sterilizing purified water in purified water tank 13, and reverse osmosis membrane during chemical washing The module 12 and the purified water tank 13 are provided with a chemical solution tank / temporary storage tank 63 (temporary storage means) for storing a chemical solution for cleaning and disinfecting.

  Furthermore, this purified water production apparatus has a raw water supply line 91 having one end connected to a water supply or a storage tank and the other end connected to the temperature adjusting means 90, one end connected to the temperature adjusting means 90, and the other end being raw water. The raw water supply line 92 connected to the tank 10, one end connected to the raw water tank 10, the other end connected to the activated carbon filter 60, and the raw water supply provided with the motorized valve 20 and the raw water pump 30 on the downstream side in the middle A line 40 and a raw water transfer line 70 having one end connected to the activated carbon filter 60 and the other end connected to the nanofiltration membrane module 61 are provided. One end is connected to the nanofiltration membrane module 61, the other end is connected to the reverse osmosis membrane modules 12 and 12, and the motorized valve 21 and the pressurizing pump 31 downstream are provided on the way. 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 and a purified water / water supply line 43 provided with an electric valve 23 downstream from the water supply pump 33. Further, one end is connected to the reverse osmosis membrane modules 12, 12, and the concentrated water discharge line 44 in which the flow rate adjusting valve 24 and the electric valve 25 are provided on the downstream side, and the other end is the flow rate of the concentrated water discharge line 44. It branches from between the regulating valve 24 and the motor-operated valve 25, and the other end is connected to the soft water transfer line 41 between the motor-operated valve 21 and the pressurizing pump 31. The concentrated water return line 45 provided with the valve 27 and one end branch from the downstream side of the electric valve 25 of the concentrated water discharge line 44, the other end connected to the raw water tank 10, and an electric valve 80 provided in the middle. And a concentrated water return line 71.

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 adjustment valve 81 in the middle, and one end from the flow rate adjustment valve 81 of the concentrated water discharge line 72. The other end also branches from the downstream side, and 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 is provided with a concentrated water return line 73 provided with a check valve 82 in the middle. Further, one end branches from between the water supply pump 33 and the electric valve 23 of the purified water supply line 43 and the other end is connected to the purified water tank 13, and one end is a water supply pump of the purified water supply line 43. The purified water discharge line 47 branched from between the motor 33 and the motor-operated valve 23 and provided with the motor-operated valve 28 is connected to the motor-operated valve, the flow rate adjusting valve, and the pumps to control them. A control unit (not shown) is provided and schematically configured.
Further, in this purified water production apparatus, one end branches from between the water supply pump 33 and the electric valve 23 of the purified water supply line 43, the other end is connected to the chemical tank / temporary storage tank 63, and the electric valve 83 is provided in the middle. The purified water return line 74 is provided with one end connected to the chemical tank / temporary storage tank 63 and 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 supply line 48 provided with a valve 29.

  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. The concentrated water discharge line 44 allows the concentrated water discharged from the concentrated water discharge ports 59 and 59 of the reverse osmosis membrane modules 12 and 12 to flow between the reverse osmosis membrane modules 12 and 12 and the flow rate adjustment valve 24. The first flow path 44a branches into a second flow path 44b through which concentrated water discharged from the raw water inlets 57, 57 of the reverse osmosis membrane modules 12, 12 flows, and a switching valve 85 is provided at the junction of these flow paths. Is provided. Further, 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 the second flow path 41b and the first flow path 44a in the vicinity of the concentrated water discharge port 59 are used. Common piping is used.

  As the temperature adjusting means 90, a known electric heater, heat exchanger, mixing valve for mixing hot water or cold water, or the like may be used, or a combination thereof may be used. Although not shown, the temperature adjustment means 90 may be provided in the raw water tank 10.

  As the reverse osmosis membrane module 12, a reverse osmosis membrane element 55 is formed by winding a plurality of reverse osmosis membranes 50 in a cylindrical shape around a water collection pipe 52 in which a plurality of water collection holes 51 are formed as shown in FIG. A so-called spiral reverse osmosis membrane module in which the reverse osmosis membrane element 55 is accommodated in a cylindrical casing 56 is usually used. More specifically, with respect to the reverse osmosis membrane element 55, three overlapping sides of the reverse osmosis membrane 50 are bonded in a state where the liquid-permeable support fibers 53 are sandwiched between the folded reverse osmosis membranes 50. Then, the reverse osmosis membrane element 55 is formed by overlapping the mesh spacer 54 on the reverse osmosis membrane 50 containing the liquid-permeable support fiber 53 and then winding it around the water collecting pipe 52 in multiple layers. .

  In the reverse osmosis membrane module 12, raw water is introduced into a raw water inlet 57 formed on one end face side of the reverse osmosis membrane element 55 and flows through a flow path formed by a mesh spacer 54. During this time, part of the raw water permeates 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 the permeated water at the end of the water collecting pipe 52. It is discharged from the outlet 58. 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 discharge port 59 formed on the other end face side of the reverse osmosis membrane element 55.

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.
In addition, although the reverse osmosis membrane module 12 is using two in parallel in the example of FIG. 1, what is necessary is just to use the number according to the required amount of water.
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 permeates the nanofiltration membrane and concentrated water that does not permeate 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. According to the definition of IUPAC {Journal of Membrane Science, 120, 149-159 (1996) "Membrane and Membrane Process Terminology (1996 IUPAC Recommended)"}, what is a nanofiltration membrane? “Pressure-driven membrane separation process in which particles and polymers smaller than 2 nm are blocked” (By the way, microfiltration membrane (MF membrane) is larger than 0.1 μm, ultrafiltration membrane (UF membrane) ) Is a film capable of blocking films in 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 of the membrane surface and the ionic components in the solute, and the inherent blocking performance and permeation performance of the membrane. Is shown.

In the present invention, it is preferable to use a nanofiltration membrane using polyamide as a material (hereinafter referred to as a polyamide-based nanofiltration membrane). 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. Polyamide-based nanofiltration membranes can secure a larger permeate flow rate, have a wider usable pH range and temperature range, have higher endotoxin removal capability, and are more resistant to chemicals than cellulose acetate-based nanofiltration membranes. High nature.
In addition, when using polyamide as a reverse osmosis membrane, the effect of this invention will be more suitably acquired even if it does not use heat resistant polyamide, when the raw | natural water temperature in a raw | natural water tank shall be 25 to 45 degreeC by the said temperature control means. Therefore, it is preferable.

  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 is roughly composed of a processing unit, an interface unit, and a calendar timer. The control unit adjusts the temperature of the temperature adjusting means 90, starts supplying raw water to the activated carbon filter 60, the nanofiltration membrane module 61, and the reverse osmosis membrane module 12, stops supplying raw water thereto, and the reverse osmosis membrane module 12. -Purified water tank 13-Chemical liquid tank / temporary storage tank 63-Reverse osmosis membrane module 12 in the order of purified water circulation, and chemical liquid from the chemical liquid tank / temporary storage tank 63 to the reverse osmosis membrane module 12 and the purified water tank 13 The start of supply and the start of discharge of the chemical solution and purified water from the reverse osmosis membrane module 12 and the purified water tank 13 can be controlled, and these controls can be performed at any date and time set in the calendar timer. is there.
For the temperature adjustment, a temperature sensor is provided on the upstream side of the temperature adjustment means 90, that is, in the raw water supply line 91, and the temperature of the raw water supplied from the water supply is measured. It is performed by adjusting 90 on / off and / or strength. The temperature of the raw water is preferably adjusted to about 25 ° C. by the temperature adjusting means 90.

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 is configured by a memory and a central processing unit (CPU). A program for realizing the function of the processing unit is loaded into the memory. The function may be realized by executing the function.
In addition, an input device, a display device, and the like are connected to the control unit 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.

Next, the manufacturing method of the purified water using this purified water manufacturing apparatus is demonstrated.
When 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. . When the production of purified water is started, the soft water transfer line 41 selects the first flow path 41a by the switching valve 84, and the concentrated water discharge line 44 selects the first flow path 44a by the switching valve 85. Has been.

  The raw water supplied from the water supply or the like passes through the raw water supply line 91 and is supplied to the temperature adjusting means 90. The raw water whose temperature has been adjusted by the temperature adjusting means 90 passes through the raw water supply line 92 and is stored in the raw water tank 10. 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 case where the purified water production apparatus does not produce purified water will be described.
Based on a stop signal from the calendar timer of the control unit in which purified water is not used, such as at night or on holidays, or based on the user's stop operation, the control unit stops the operation of the temperature adjusting means 90 and the raw water pump 30. Then, the electric valve 20 of the raw water supply line 40, the electric valve 21 of the soft water transfer line 41, the electric valve 23 of the purified water supply line 43 and the electric valve 25 of the concentrated water discharge line 44 are closed to stop the production of purified water. .

  At the same time, the control unit opens the electric valve 83 of the purified water return line 74 and the electric valve 29 of the chemical solution supply line 48. As a result, 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 passes through the purified water return line 74 to serve as the chemical tank / temporary storage tank 63. And is temporarily stored in the chemical tank / temporary storage tank 63. The chemical tank / temporary storage tank 63 is empty except during the chemical washing of the apparatus. The purified water in the chemical liquid tank / temporary storage tank 63 is further returned to the soft water transfer line 41 through the chemical liquid supply line 48.

  The purified water returned to the soft water transfer line 41 is pressurized by the pressurizing pump 31 of the soft water transfer line 41, and then passes through the first flow path 41a (or the second flow path 41b) to the reverse osmosis membrane module 12. , 12. 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 does not produce purified water, the purified water in the purified water tank 13 is supplied in the order of the water pump 33, the chemical tank / temporary storage tank 63, the pressure pump 31, and the reverse osmosis membrane module 12. Sent 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 33 -the chemical tank / temporary storage tank 63 -the pressurizing pump 31 -the reverse osmosis membrane module 12 -the purified water tank 13.

  In the purified water production apparatus as described above, the nanofiltration membrane module 61 is used as the water softening means instead of the pretreatment apparatus equipped with the conventional ion exchange resin, so the retention of raw water is reduced. Can be difficult to propagate bacteria. In addition, bacteria and endotoxins in the raw water are also 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 raw water, the burden on the reverse osmosis membrane module 12 is reduced, and the frequency of washing the reverse osmosis membrane module 12 can be reduced. it can.

  In this purified water production apparatus, since the temperature is adjusted so that the temperature of the raw water is always constant by the temperature adjusting means 90, the permeate flow rate of the nanofiltration membrane and the reverse osmosis membrane should be kept constant. Can do. Therefore, a stable amount of purified water can be secured throughout the year without being affected by changes in water temperature due to the season.

  Further, in this purified water production apparatus, a return line 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 (purified water return line 74 and chemical solution supply line 48). ), The purified water can be circulated in the purified water production apparatus when the purified water is not produced. Thereby, even when purified water is not produced, no stagnant water is generated in the pressurizing pump 31, the reverse osmosis membrane module 12, the purified water tank 13, the water pump 33, and the lines connecting them. It is possible to further suppress bacterial growth and endotoxin generation. Further, if the chemical tank / temporary storage tank 63 is provided in the middle of the return line, even if the motor valve 29 of the chemical liquid supply line 48 malfunctions and the raw water flows back through the chemical liquid supply line 48, the raw water Is stored in the chemical tank / temporary storage tank 63, so that the raw water flows into the secondary side (purified water side) of the purified water tank 13 and the reverse osmosis membrane module 12 through the purified water return line 74 and contaminates the purified water. There is no end. Further, the chemical solution at the time of chemical washing can be circulated by the return line, and at the same time, the reverse osmosis membrane module 12 and the purified water tank 13 can be washed and disinfected.

  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 appropriately determined. Can be switched. As a result, the raw water can flow evenly through the entire flow path formed by the mesh spacer 54, the drift and retention of the raw water in the mesh spacer 54 on the concentrated water outlet 59 side is reduced, and the propagation of bacteria and the generation of endotoxin are further increased. It can be suppressed.

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.

Explanation of symbols

10 Raw water tank 12 Reverse osmosis membrane module (refining means)
13 Purified water tank 50 Reverse osmosis membrane 61 Nanofiltration membrane module (softening means)
63 Chemical tank and temporary storage tank (temporary storage means)
74 Purified water return line 90 Temperature control means

Claims (4)

Temperature adjusting means for adjusting the temperature of the raw water;
Water softening means for softening raw water with a nanofiltration membrane;
A purified water production apparatus comprising a purification means for obtaining purified water by filtering softened raw water through a reverse osmosis membrane.   The purified water production apparatus according to claim 1, wherein the temperature adjusting means is provided in a raw water tank that stores raw water. Temperature adjusting means for adjusting the temperature of the raw water;
Water softening means for softening raw water with a nanofiltration membrane;
A purification means for obtaining purified water by filtering the softened raw water through a reverse osmosis membrane;
Storage means for storing purified water;
A return line for returning the purified water of the storage means to the upstream side of the purification means;
A purified water production apparatus comprising: temporary storage means for temporarily storing purified water returned in the middle of a return line. The purified water production apparatus according to claim 3, wherein the temperature adjusting means is provided in a raw water tank that stores raw water.

Images