JP2019107617A - Sterilization method of pure water production apparatus - Google Patents

Abstract

To provide improved efficiency of sterilization treatment with hot water.SOLUTION: A method of sterilizing a pure water production apparatus 1 comprising: a membrane filtration device 3; and an electric deionized water production device 4 connected to the downstream side of the membrane filtration device 3 and supplied with permeated water from the membrane filtration device 3. The method has: a step in which, after the water to be treated from a pretreatment device stored in a water to be treated tank 2 is sequentially supplied to the membrane filtration device 3 and the electric deionized water production device 4, it is returned to the water to be treated tank 2, thus circulating the water to be treated along a circulation path including the membrane filtration device 3 and the electric deionized water producing device 4; and a step of heating the water to be treated circulating along the circulation path to a predetermined temperature, and then cooling it after held for predetermined time, thus sterilizing the membrane filtration device 3 and the electric deionized water production device 4. The step of sterilizing is performed within the range of the conditions that a cation exchanger CE and an anion exchanger AE packed in a deionization chamber D of the electric deionized water production device 4 are not broken.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of sterilizing a pure water production apparatus.

  Conventionally, it has reverse osmosis membrane (RO membrane) or nanofiltration membrane (NF membrane) as an apparatus for producing pure water (purified water) used for pharmaceutical production etc., and industrial water, well water, city water etc. Combined with a membrane filtration unit that separates the raw water into permeate and concentrated water, and an electro-deionized water production unit that produces deionized water (pure water) by passing the permeate through the ion exchanger. A pure water production system is known. In such a pure water production apparatus, due to the nature of producing pure water used for pharmaceutical production etc., in order to secure the requirements of the Japanese Pharmacopoeia, the sterilization treatment to reduce the number of viable bacteria in the system is regularly performed. It has been done. This sterilization treatment is generally performed by passing hot water of, for example, 60 ° C. or more into the system.

  Patent Document 1 describes a method of heating pure water manufactured by a pure water manufacturing apparatus and passing the water through the system. Specifically, pure water produced by the pure water production apparatus is temporarily stored in the raw water tank, and the pure water is heated and sequentially supplied to the membrane filtration apparatus and the electro-deionized water production apparatus before being fed to the raw water tank. A method is described in which heated pure water is circulated in the system by refluxing. According to this method, it is possible to sterilize the membrane filtration apparatus and the electrodeionization water production apparatus at one time, and it is possible to reduce the amount of water used and the number of processes compared to the case of sterilizing these individually. It becomes possible to perform efficient sterilization treatment.

Unexamined-Japanese-Patent No. 2004-74109

  However, in the method described in Patent Document 1, when carrying out the sterilization process, the raw water stored in the raw water tank during normal operation (pure water production) is discharged to the outside, and then the heated pure water is treated in the raw water tank Need to be stored. That is, the method described in Patent Document 1 still requires such an extra step every time sterilization is performed, and the point that a certain amount of water is wasted in accordance with it. There is room for improvement.

  Therefore, an object of the present invention is to provide a method for sterilizing a pure water production apparatus, which realizes further efficiency improvement of sterilization treatment with hot water.

  In order to achieve the above-mentioned object, the sterilizing method of the pure water production apparatus of the present invention comprises a membrane filtration apparatus having a reverse osmosis membrane or a nanofiltration membrane, and a downstream side of the membrane filtration apparatus connected from the membrane filtration apparatus An apparatus for producing deionized water supplied with permeated water, which is located between an anode and a cathode and is partitioned by an anion exchange membrane on the anode side and a cation exchange membrane on the cathode side, and a cation exchanger and an anion An electric deionized water production apparatus having a demineralization chamber filled with an exchange body, and a method for sterilizing a pure water production apparatus comprising: treated water from a pretreatment apparatus stored in a treated water tank Are sequentially supplied to the membrane filtration apparatus and the electrodeionization water producing apparatus, and then returned to the treated water tank, whereby the water to be treated along the circulation path including the membrane filtration apparatus and the electrodeionization water producing apparatus Circulation process and circulation along the circulation path. The step of sterilizing the membrane filtration apparatus and the electrodeionization water production apparatus by heating the water to be treated to a predetermined temperature and holding it for a certain period of time and then cooling; It is carried out in the range of the conditions which the cation exchanger and anion exchanger which were filled in the deionization chamber of the deionized water production apparatus do not break through.

  According to the sterilizing method of such a pure water production apparatus, there is no need to discharge the treated water (raw water) stored in the treated water tank (raw water tank) during normal operation, and the amount of water used and the process Both can be reduced. The use of raw water as hot water for heat sterilization may affect the treated water quality of the electric deionized water production equipment at the time of resumption of operation, but the deionization chamber of the electric deionized water production equipment is filled with the raw water. The effect can also be minimized by circulating the raw water within the range where the cation exchanger and the anion exchanger do not break through.

  As mentioned above, according to this invention, the further efficiency improvement of the sterilization process by a hot water is realizable.

It is a schematic block diagram of the pure water manufacturing apparatus which concerns on one Embodiment of this invention. It is a graph which shows the time change of treated water specific resistance in an example and comparative example 1.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  Fig.1 (a) is a schematic block diagram of the pure-water manufacturing apparatus based on one Embodiment of this invention. FIG.1 (b) is a schematic block diagram of the electrodeionization water manufacturing apparatus which comprises the pure water manufacturing apparatus of Fig.1 (a). The configurations of the pure water producing apparatus and the electric deionized water producing apparatus shown in the drawings are merely examples, and are not intended to limit the present invention, and can be appropriately changed according to the use purpose, application, and required performance of the apparatus. It goes without saying that

  The pure water production apparatus 1 sequentially treats the water to be treated (raw water) to produce pure water, and as shown in FIG. 1 (a), the raw water tank 2, the membrane filtration device 3, and the electric type And a deionized water production unit 4.

  The membrane filtration apparatus 3 removes impurities in the raw water supplied from the raw water tank 2 to generate permeated water, and separates the raw water into concentrated water containing the impurities and permeated water from which the impurities are removed. Reverse osmosis membrane (RO membrane) or nanofiltration membrane (NF membrane). The membrane filtration apparatus 3 includes a supply line L1 for supplying raw water from the raw water tank 2 to the membrane filtration apparatus 3, a permeate water line L2 for circulating permeate water from the membrane filtration apparatus 3, and concentration from the membrane filtration apparatus 3. A concentrated water line L3 for circulating water is connected. The concentrated water line L3 is branched into a drainage line L4 for discharging a part or all of the concentrated water flowing in the concentrated water line L3 to the outside and a reflux water line L5 for refluxing to the raw water tank 2. A raw water tank 2 is connected to a pretreatment device (not shown) for removing turbidity and dechlorination through a raw water supply line L6, and pretreated raw water (for example, water having a conductivity of 1000 μS / cm or less) Will be supplied as needed.

  The heat exchanger 5 and the pressurizing pump 6 are provided in the supply line L1. The heat exchanger 5 is provided in order to heat the raw water supplied to the membrane filtration apparatus 3 at the time of the sterilization process mentioned later, and to produce a hot water. The pressure pump 6 is provided to supply raw water stored in the raw water tank 2 to the membrane filtration device 3 together with a water pump (not shown) provided between the raw water tank 2 and the heat exchanger 5. ing. The pressure pump 6 has its rotation speed controlled by an inverter (not shown), and also has a function of adjusting the supply pressure of the raw water to the membrane filtration device 3. The drainage line L4 and the reflux water line L5 are respectively provided with valves V1 and V2 for switching the flow path of the concentrated water flowing in the concentrated water line L3.

  The electrodeionization water producing apparatus 4 is an apparatus for simultaneously performing the deionization (demineralization) treatment of the water to be treated by the ion exchanger and the regeneration treatment of the ion exchanger. The electrodeionization water producing apparatus 4 is connected to the downstream side of the membrane filtration apparatus 3 via the permeated water line L2, and permeated water from the membrane filtration apparatus 3 is supplied as treated water. The deionized water production apparatus 4 includes a treated water line L7 for circulating treated water (deionized water) from the electric deionized water production apparatus 4 and supplying the treated water to a treated water tank or a use point; A concentrated water discharge line L8 for discharging the concentrated water from the ion water production apparatus 4 to the outside is connected.

  A valve V3 is provided on the treated water line L7, and a treated water reflux line L9 is connected to the upstream side thereof via a valve V4. The treated water return line L9 is connected to the raw water tank 2 on the opposite side. Thus, for example, when the apparatus starts up or restarts operation, or when there is no demand for treated water (pure water) at the point of use, the treated water produced by the electrodeionization water producing apparatus 4 is returned to the raw water tank 2 Circulation operation can also be performed. Further, a valve V5 is provided in the concentrated water discharge line L8, and a concentrated water reflux line L10 is connected to the upstream side thereof via the valve V6. The concentrated water reflux line L10 is connected to the raw water tank 2 on the opposite side. Thereby, depending on the water quality of the concentrated water from the electrodeionization water producing apparatus 4, a part or all of the concentrated water can be returned to the raw water tank 2.

  As shown in FIG. 1 (b), the electrodeionization water producing apparatus 4 has an anode chamber E1 provided with an anode 11, a cathode chamber E2 provided with a cathode 12, and a space between the anode chamber E1 and the cathode chamber E2. In the deionization chamber D, the anode-side concentrating chamber C1 adjacent to the desalting chamber D via the anion exchange membrane a1 on the anode 11 side of the desalting chamber D, and cations on the cathode 12 side of the desalting chamber D A deionization compartment D and a cathode side concentration compartment C2 adjacent to the deionization compartment D are provided via the exchange membrane c1. The anode side concentration chamber C1 is adjacent to the anode chamber E1 via the cation exchange membrane c2, and the cathode side concentration chamber C2 is adjacent to the cathode chamber E2 via the anion exchange membrane a2.

  The deionization chamber D is divided by the intermediate ion exchange membrane m into a first small deionization chamber D1 and a second small deionization chamber D2. The first small deionization chamber D1 is adjacent to the anode side concentration chamber C1 through the anion exchange membrane a1, and the second small deionization chamber D2 is adjacent to the cathode side concentration chamber C2 through the cation exchange membrane c1. doing. The intermediate ion exchange membrane m is, for example, a single membrane of an anion exchange membrane or a cation exchange membrane, or a bipolar membrane.

  The deionization chamber D is filled with a cation exchanger AE and an anion exchanger CE. Specifically, the first small deionization chamber D1 is filled with an anion exchanger AE in a single bed form, and the second small deionization chamber D2 includes a cation exchanger CE and an anion exchanger AE. It is packed in a double bed form. More specifically, the second small deionization chamber D2 is divided into two regions along the flow direction of the water to be treated, and the upstream region is filled with the cation exchanger CE in a single bed form, In the downstream region, anion exchangers AE are packed in single bed form. As a cation exchanger filled in the deionization chamber D, a cation exchange resin, a cation exchange fiber, a monolithic porous cation exchanger, etc. may be mentioned, and the most versatile cation exchange resin is preferably used. As a kind of cation exchanger, weak acid cation exchanger, strong acid cation exchanger, etc. are mentioned. As an anion exchanger filled in the deionization chamber D, anion exchange resin, anion exchange fiber, monolithic porous anion exchanger etc. may be mentioned, and the most versatile anion exchange resin is preferably used. As a kind of anion exchanger, a weak base anion exchanger, a strong base anion exchanger, etc. are mentioned.

  In addition, in order to suppress the electrical resistance of the electrodeionization water production apparatus 4, it is preferable that the anode side concentration chamber C1 and the cathode side concentration chamber C2 be filled with ion exchangers, respectively. Further, it is preferable that the anode chamber E1 and the cathode chamber E2 be filled with a conductive substance such as an ion exchanger, in order to suppress the electrical resistance of the electrodeionization water producing apparatus 4. As an example, an anion exchanger is filled in the anode side concentration chamber C1, the cathode side concentration chamber C2, and the cathode chamber E2, and a cation exchanger is filled in the anode chamber E1.

  The permeated water line L2 from the membrane filtration unit 3 is branched into a plurality (three in the illustrated example) and connected to the first small deionization chamber D1, the anode side concentration chamber C1, and the cathode side concentration chamber C2, respectively ing. The first small deionization chamber D1 forms a serial flow path with the second small deionization chamber D2, and the downstream side thereof is connected to the treated water line L7. The anode side concentration chamber C1 and the cathode side concentration chamber C2 form a parallel flow path, and the downstream side thereof is connected to a concentrated water discharge line L8. Thus, the permeated water from the membrane filtration unit 3 is supplied as treated water to the first and second small deionization chambers D1 and D2, and is supplied as concentrated water to the anode side concentration chamber C1 and the cathode side concentration chamber C2. Ru. Although not shown, lines for supplying and discharging electrode water are also connected to the anode chamber E1 and the cathode chamber E2.

  The permeated water (to-be-treated water) supplied from the membrane filtration apparatus 3 through the permeated water line L2 has its ion component removed when passing through the deionization chamber D, and treated water (deionized water) is treated water line L8 Through the water supply tank or point of use. At this time, the ionic components removed in the desalting chamber move to concentration chambers C1 and C2 adjacent to the desalting chamber D due to a potential difference generated by applying a DC voltage between the two electrodes 11 and 12. Specifically, the cation component is drawn to the cathode 12 side, passes through the cation exchange membrane c1 and moves to the cathode side concentration chamber C2, and the anion component is drawn to the anode 11 side, and passes through the anion exchange membrane a1. And move to the anode side concentration chamber C1. The ion components thus transferred to the concentration chambers C1 and C2 are taken into the concentrated water supplied to the concentration chambers C1 and C2 and discharged to the outside through the concentrated water discharge line L8. However, depending on the quality of the concentrated water, part or all of it may be returned to the raw water tank 2. On the other hand, in the deionization chamber D, a water dissociation reaction (a reaction in which water is dissociated into hydrogen ions and hydroxide ions) proceeds continuously. The hydrogen ions are exchanged with the cation component adsorbed to the cation exchanger, and the hydroxide ions are exchanged with the anion component adsorbed to the anion exchanger. Thus, the cation exchanger and the anion exchanger charged in the deionization compartment D are regenerated respectively.

  As described at the beginning, the illustrated configuration of the electrodeionization water producing apparatus 4 is merely an example, and the configuration (number, arrangement, etc. of each chamber according to the purpose of use, application, and required performance of the apparatus. And changes in the flow path configuration and addition of valves, measuring instruments, etc. For example, two or more deionization chambers may be provided. In this case, the desalting chamber and the concentration chamber are alternately provided via a cation exchange membrane or an anion exchange membrane, and two or more desalting chambers form a serial or parallel flow path. Further, the form of packing of the cation exchanger and the anion exchanger in the desalting chamber is not limited to that illustrated either. For example, the first small desalting chamber is filled with the cation exchanger in a single bed form, and the second In the small deionization chamber, the anion exchanger and the cation exchanger may be packed in single bed form.

  The pure water production apparatus 1 of the present embodiment produces pure water used for pharmaceutical production and the like. Therefore, in the present embodiment, a sterilizing step of reducing the number of viable bacteria in the system with hot water is periodically performed between pure water production in normal operation. Hereinafter, this sterilization step will be described.

  In the sterilizing process, the temperature of the system is maintained after heating to about 60 ° C. or higher, preferably about 90 ° C. by the heat exchanger 5 and circulating the raw water stored in the raw water tank 2 in the system, preferably for about 90 ° C. It is a process of cooling to a temperature suitable for pure water production. A sterilization process is performed, and a pure water production apparatus 1 including a supply line L1, a membrane filtration apparatus 3, a permeated water line L2, an electric deionized water production apparatus 4, a treated water line L7, and a treated water reflux line L9. The inside of the system is sterilized.

  When the sterilization process is started, the operation (application of the DC voltage) of the electrodeionization water producing apparatus 4 is stopped, and the pure water production is stopped. Then, the valve V3 of the treated water line L7 is closed, and the valve V4 of the treated water return line L9 is opened. As a result, the raw water in the raw water tank 2 is sequentially supplied to the membrane filtration unit 3 and the electric deionized water production unit 4 and then returned to the raw water tank 2 to supply the feed line L1, the membrane filtration unit 3, and the permeation. The water is circulated along a circulation path including the water line L2, the electrodeionization water producing apparatus 4, the treated water line L7, and the treated water reflux line L9. At the same time, the heat exchanger 5 heats the circulating raw water to 60 ° C. to 90 ° C., and the temperature is maintained. Thus, the inside of the system of the pure water production apparatus 1 is sterilized by the circulation of the raw water (hot water) kept at a high temperature. At this time, the valve V1 of the drainage line L4 is closed and the valve V2 of the reflux water line L5 is opened, whereby the concentrated water line L3 and the reflux water line L5 are also sterilized by the hot water. Further, the valve V5 of the concentrated water discharge line L8 is closed, and the valve V6 of the concentrated water reflux line L10 is opened, whereby the concentrated water reflux line L10 is also sterilized by the hot water.

  After circulation of the hot water has been performed for a certain period of time, the heat exchanger 5 cools the circulating hot water to, for example, less than 45 ° C., and the sterilization process is completed. Then, before the normal operation is resumed in the pure water production apparatus 1, the raw water in the raw water tank 2 used for the hot water sterilization is discharged to the outside through a drainage line (not shown) connected to the raw water tank 2 Be done. Thereafter, the raw water is newly supplied to the raw water tank 2 through the raw water supply line L6, and the normal operation is resumed in the pure water production apparatus 1. When the normal operation is resumed, the valve V4 of the treated water reflux line L9 is closed, and the valve V3 of the treated water line L7 is opened, and the pure water produced by the pure water producing apparatus 1 is treated water tank or use Supplied to points.

  As described above, in the present embodiment, since the raw water stored in the raw water tank 2 is heated and circulated as it is during normal operation, there is no need to discharge the raw water in the raw water tank 2 to the outside before the sterilizing step. . That is, hot water sterilization using pure water instead of raw water requires a step of replacing the raw water stored in the raw water tank with pure water, but in this embodiment, such an extra step is necessary. There is no waste of a certain amount of water. As a result, both the amount of water used and the number of processes can be reduced, and further efficiency improvement of the sterilization treatment with hot water can be realized.

  However, there are the following concerns about heating and sterilizing raw water. Although the detailed description is omitted, if the temperature of the raw water becomes high, it is necessary to reduce the supply pressure of the raw water to the membrane filtration device due to the structure of the RO membrane or the NF membrane. As a result, the water quality of the permeate separated by the membrane filtration device may deteriorate, and the water quality standard of the water supply to the electric deionized water production device may be exceeded. There is a concern that the treated water quality of water production equipment will be affected. Therefore, in a pure water production apparatus equipped with an electrodeionization water producing apparatus, as described in Patent Document 1, it is general to perform hot water sterilization using pure water.

  However, according to the verification of the present inventors, even when the water quality of the permeated water from the membrane filtration device is deteriorated and the water quality standard of the water supply to the electrodeionization water producing device is exceeded, within a certain range of conditions. It has been found that if the operation is resumed, the influence on the treated water quality of the electrodeionization water producing apparatus can be minimized. The conditions are conditions which the cation exchanger and the anion exchanger with which the deionization chamber of the electrodeionization water production apparatus was filled do not break through. That is, if the cation exchanger and the anion exchanger are broken due to the deterioration of the water quality of the permeated water, it may take a long time to start up the water quality after resuming operation as shown in a comparative example described later. Such problems can be avoided as long as the exchanger and the anion exchanger do not break through.

  Therefore, in the sterilization step of the present embodiment, the hot water (heated raw water) is within the range where the cation exchanger and the anion exchanger filled in the deionization chamber of the electrodeionization water producing apparatus do not break through. It is supposed to carry out the circulation of As a result, it is possible to avoid the problems related to the rise of the water quality, and to minimize the influence on the treated water quality of the electrodeionization water producing apparatus after the restart of the operation. Here, the specific conditions for preventing the cation exchanger and the anion exchanger from passing through can also be determined by experiment, but whether the parameters determined from the apparatus configuration and the operating conditions satisfy the following conditions It is preferable to confirm beforehand by calculation. The conditions are included in the raw water supplied to the desalting chamber during the sterilization step relative to the product of the volume (L) of the cation exchanger charged in the desalting chamber and the total exchange capacity (eq / L-R). Contained in the raw water supplied to the demineralization chamber during the sterilization step relative to the product of the ratio of the total number of equivalent equivalents of cation (eq) to the volume of the anion exchanger packed in the deionization chamber and the total exchange capacity And the ratio of the total number of equivalents of the anions to be obtained is equal to or less than a predetermined value. The predetermined value is, for example, 50% as shown in an embodiment described later.

  Under the above conditions, the sum of the respective equivalents of cations and anions contained in the raw water supplied to the desalting chamber during the sterilization step (the sum of each of the cation load and the anion load during the sterilization step) is It is calculated as follows. First, the equivalent concentrations of cations and anions contained in the raw water supplied from the pretreatment device are measured in advance, and the measured equivalent concentrations of the cations and anions and the temperature dependency of the inhibition rate of the RO membrane or NF membrane Calculate equivalent concentrations of cations and anions contained in the hot water supplied to the desalting chamber at each temperature. Then, based on the calculated equivalent concentrations of the cation and the anion, the flow rate of the hot water supplied to the desalting chamber at the time of the sterilization step, and the required time (water flow time) of the sterilization step, The sum of the numbers of equivalents of cations and anions contained in the supplied hot water is calculated. The cations and cations to be measured are ideally all anions and cations in the raw water.

  The present invention will now be described in more detail by way of specific examples.

(Example)
In the present embodiment, the above-described sterilization step is carried out using the pure water production apparatus shown in FIG. 1, and the treated water quality (treated water specific resistance) from the resumption of normal operation to 24 hours after is measured every two hours. did. Use RO water of 200 L in volume as raw water tank (raw water tank) and use RO permeated water (permeated water separated by reverse osmosis membrane) with electric conductivity of about 300 μS / cm as raw water (raw water) It was. The sodium concentration in the raw water was about 17 times the water quality standard of the water supplied to the electrodeionization water producing apparatus.

  The H-type cation exchange resin and the OH-type anion exchange resin are respectively used as a cation exchanger and an anion exchanger filled in the desalting chamber, and the first small desalting chamber and the second small desalting chamber during the sterilization step Linear velocity (LV) at 63 m / h and 72 m / h, respectively. The time required for the sterilization process is 3 hours in total for each of the raw water temperature raising, temperature holding and temperature lowering for 1 hour, and the maximum temperature reached of the raw water is 87 ° C.

  In the apparatus configuration and operating conditions described above, the ratio of the total of the cation load in the sterilization step to the product of the volume of the cation exchanger packed in the desalting chamber and the total exchange capacity is 43%, The ratio of the total of the anion load in the sterilization step to the product of the volume of the anion exchanger and the total exchange capacity was 15%.

(Comparative example 1)
Before carrying out the sterilization step, the step of replacing the raw water stored in the raw water tank with pure water was carried out, and measurements were carried out under the same conditions as in the example except that pure water was used as hot water for heat sterilization. went.

(Comparative example 2)
The measurement was carried out under the same conditions as in Example except that each in the form of a salt was used as the cation exchanger and the anion exchanger packed in the desalting chamber.

  FIG. 2 is a graph showing the measurement results in the example and the comparative example 1, and shows the treated water resistivity with respect to the elapsed time after resumption of normal operation. Table 1 shows the measurement results in the example and the comparative examples 1 and 2, specifically, the treated water specific resistance 2 hours after resumption of operation.

  In the embodiment, compared to Comparative Example 1 in which pure water is used as hot water for heat sterilization, the amount of water used for the sterilization process can be reduced by the volume (200 L) of the raw water tank, and the pure water replacement process requires Although it is advantageous in that the time can be reduced (this effect increases as the scale of the apparatus increases), as can be seen from FIG. It was confirmed that there was not. Moreover, as shown in Table 1, in the Example, compared with the comparative example 2 which used the salt-form ion exchange resin, it was confirmed that a favorable result is acquired regarding the rise of water quality. Comparative Example 2 simulates a state in which the ion exchanger in the deionization chamber of the electrodeionization water production apparatus has broken through, so that the rising of the water quality is good in the example in the sterilization step. It is considered that this is because the ion exchanger in the demineralization chamber of the electrodeionization water production apparatus did not break through.

DESCRIPTION OF SYMBOLS 1 Pure water production apparatus 2 Raw water tank 3 Membrane filtration apparatus 4 Electric type deionized water production apparatus 5 Heat exchanger 6 Pressure pump 11 Anode 12 Cathode D Deionization room D1 1st small deionization room D2 2nd small removal Salt chamber C1 Anode-side concentration chamber C2 Cathode-side concentration chamber E1 Anode chamber E2 Cathode chamber a1, a2 Anion exchange membrane c1, c2 Cation exchange membrane m Intermediate ion exchange membrane L1 supply line L2 permeate water line L3 concentrate water line L4 drainage line L5 Reflux water line L6 Raw water supply line L7 Treated water line L8 Concentrated water discharge line L9 Treated water reflux line L10 Concentrated water reflux line V1 to V6 Valve

Claims (3)

A membrane filtration apparatus having a reverse osmosis membrane or a nanofiltration membrane, and an electrodeionization water producing apparatus connected to the downstream side of the membrane filtration apparatus and supplied with permeated water from the membrane filtration apparatus, comprising: an anode An electric deionized water having a deionization chamber located between a cathode and separated by an anion exchange membrane on the anode side and a cation exchange membrane on the cathode side and filled with a cation exchanger and an anion exchanger A method of sterilizing a pure water production apparatus, comprising: a production apparatus;
The membrane filtration is performed by sequentially supplying the water to be treated from the pretreatment device stored in the water to be treated tank to the membrane filtration device and the electric deionized water production device, and then returning the water to the water to be treated tank. Circulating the water to be treated along a circulation path including an apparatus and the electrodeionization water producing apparatus;
Heating the treated water circulating along the circulation path to a predetermined temperature, holding the water for a certain period of time and cooling it, thereby sterilizing the membrane filtration apparatus and the electrodeionization water producing apparatus; Including
The step of sterilizing is performed under the condition that the cation exchanger and the anion exchanger packed in the deionization chamber of the electrodeionization water producing apparatus do not break out, the disinfection of the water purification system Method.   The condition is that the cation contained in the water to be treated supplied to the deionization chamber during the sterilizing step is a product of the volume of the cation exchanger and the total exchange capacity charged in the deionization chamber. Said treated material supplied to said desalting chamber during said sterilizing step with respect to the product of the ratio of the total of the number of equivalents of the volume, the volume of said anion exchanger packed in said desalting chamber and the total exchange capacity The method of sterilizing a pure water production apparatus according to claim 1, wherein the ratio of the total of the number of equivalents of anions contained in water is not more than a predetermined value.   The sterilizing method of the pure-water manufacturing apparatus of Claim 2 whose said predetermined value is 50%.

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