Purified water production device

Abstract

To provide a purified water producing apparatus in which serial two stage-type membrane modules are arranged, and cleaning / disinfection effect of the membrane module on the second stage is not inferior as compared to the membrane module on the first stage, and which is capable of efficient and excellent cleaning.SOLUTION: A purified water producing apparatus comprises: pretreatment means 11; first membrane separation means to separate pretreatment water into first permeable water and first concentrated water; second membrane separation means to separate the first permeable water into second permeable water and second concentrated water; a permeable water tank 10 to retain the second permeable water; an openable / closable first return line 16 to return the second permeable water to an upstream of the first membrane separation means; an openable / closable second return line 17 to return the second permeable water to an upstream of the second membrane separation means; and an openable / closable bypass line 13 to, while bypassing the second membrane separation means, supply the first permeable water to the permeable water tank. Purified water is produced in a state that the return line and the bypass line are closed, and the first membrane separation means and the second membrane separation means are cleaned in a state that the bypass line is opened.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a purified water production apparatus that produces highly pure purified water used as dilution water for producing dialysis fluid in a hemodialysis system. [Background technology]

[0002] The "Central Dialysis Fluid Supply System (CDDS)", which centrally prepares dialysis fluid for a large number of dialysis patients, is currently the mainstream system in Japan. To prepare a large amount of dialysis fluid, a large amount of purified water for dilution is required, and this is mainly obtained from tap water and other raw water using purified water production equipment that uses separation technology by reverse osmosis. Inside blood purifiers such as dialyzers, the purified water used to dilute and prepare the dialysis fluid that comes into contact with the patient's blood through hollow fiber membranes is in an ever-increasing demand.

[0003] In addition to purified water production equipment equipped with a single-stage reverse osmosis membrane module, there are also known systems that further improve water quality by arranging membrane modules in two stages in series, such as a combination of a first-stage nanofiltration membrane module (NF) and a second-stage reverse osmosis membrane module (RO), or a combination of both first and second stages being reverse osmosis membrane modules (RO+RO).

[0004] In order to obtain purified water with a high level of purity, it is important to regularly and reliably disinfect these membrane modules with hot water and clean them with low-concentration chemicals. However, in purified water production equipment in which membrane modules are arranged in two stages in series, what passes through the first membrane module and reaches the second membrane module is hot water or cleaning solution from the permeated water separated by the first membrane module, and as a result, the flow rate, heat amount, and amount of chemical components are all reduced, making it inefficient in terms of both cost and time to thoroughly clean and disinfect all of the piping within the equipment.

[0005] In order to solve these problems, the applicant proposed in Patent Document 1 (JP Patent Publication 2010-194092 A22) an apparatus for producing dilution water for making dialysis fluid, which enables the heating time during hot water disinfection to be shortened by circulating the concentrated water separated in the first-stage membrane module between the raw water storage tank together with the permeate water, rather than discarding it.

[0006] However, even with this technology, it is undeniable that the temperature of the hot water and the cleaning effect of the cleaning solution decrease when they reach the second-stage membrane module compared to when they are introduced into the first-stage membrane module, leaving room for improvement. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2010-194092 A Summary of the Invention [Problem to be solved by the invention]

[0008] To provide a purified water production apparatus having two serial stages of membrane modules, in which the cleaning and disinfecting effect of the second stage membrane module is not inferior to that of the first stage membrane module, and which enables efficient and excellent cleaning of the entire apparatus. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention First The purified water production equipment is A pretreatment means for obtaining pretreated water from raw water; a first membrane separation means for separating the pretreated water into a first permeate and a first concentrate; a second membrane separation means for separating the first permeate into a second permeate and a second retentate; a permeate tank for storing the second permeate; a first return line for returning the second permeate upstream of the first membrane separation means; A first return valve capable of opening and closing the first return line; a second return line for returning the second permeate upstream of the second membrane separation means; A second return valve capable of opening and closing the second return line; a bypass line for sending the first permeate to the permeate tank, bypassing the second membrane separation means; A purified water production apparatus including a bypass valve capable of opening and closing the bypass line, The method is characterized in that purified water is produced with the first return line, the second return line and the bypass line closed, and the first membrane separation means and the second membrane separation means are washed with the bypass line open.

[0010] By adopting such a configuration, during cleaning, liquid can be sent from the permeate tank through the first return line and the second return line to the upstream of the first membrane separation means and the second membrane separation means, respectively, so that the first membrane separation means and the second membrane separation means can be cleaned independently of each other via the permeate tank.

[0011] In order to solve the above problems, The present invention The second Purified water production equipment teeth , A pretreatment means for obtaining pretreated water from raw water; a first membrane separation means for separating the pretreated water into a first permeate and a first concentrate; a second membrane separation means for separating the first permeate into a second permeate and a second retentate; a permeate tank for storing the second permeate; a first return line for returning the second permeate upstream of the first membrane separation means; A first return valve capable of opening and closing the first return line; a second return line for returning the second permeate upstream of the second membrane separation means; A second return valve capable of opening and closing the second return line; a bypass line for sending the first permeate to the permeate tank, bypassing the second membrane separation means; A purified water production apparatus including a bypass valve capable of opening and closing the bypass line, Purified water is produced in a state where the first return line, the second return line, and the bypass line are closed; The first membrane separation means is washed by passing the first washing water through the bypass line and the first return line while the bypass line and the first return line are opened. and The second membrane separation means is cleaned by passing the second cleaning water through the second return line while the second return line is open. The present invention is characterized by the above.This allows the first membrane separation means and the second membrane separation means to be individually To Since the second membrane separation means can be cleaned, the same cleaning effect as the first membrane separation means can be obtained for the second membrane separation means. Furthermore, since individual cleaning is possible, the cleaning frequency or cleaning time of the first membrane separation means, which is subjected to a larger load during production of purified water, can be selectively increased, thereby reducing the cleaning time of the entire apparatus and optimizing the cleaning efficiency.

[0012] In the purified water producing apparatus of the present invention, the first washing water and / or the second washing water is preferably hot disinfecting water obtained by heating the second permeated water in the permeated water tank. In this way, during hot water disinfection, the first washing water after washing the first membrane separation means is heated while circulating through the first circulation flow path that returns the first washing water to the permeated water tank through the bypass line, and the second circulation flow path that returns the second washing water after washing the second membrane separation means to the permeated water tank, thereby making it possible to produce hot water of a predetermined temperature in a short time and to minimize the temperature drop of the hot water.

[0013] The purified water production apparatus of the present invention is a purified water production apparatus provided with a cleaning chemical injection means for injecting a cleaning chemical into the first permeate line immediately downstream of the first membrane separation means, and it is preferable that the first cleaning water and / or the second cleaning water is a diluted cleaning chemical obtained by injecting the cleaning chemical into the first permeate. This effectively prevents the high-concentration undiluted cleaning chemical from deteriorating the first membrane separation means, while cleaning the inside of the piping from the injection point of the first permeate line to the permeate tank. Furthermore, the reduction in the cleaning chemical components can be minimized, so that the cleaning time of the entire apparatus can be reduced. In addition, the membrane separation means is first washed with a relatively low-concentration diluted cleaning chemical, and then a relatively high-concentration diluted cleaning chemical is prepared and supplied to another apparatus provided downstream of the purified water production apparatus, thereby making it possible to efficiently clean the entire system including the purified water production apparatus. Effect of the Invention

[0014] According to the purified water production apparatus of the present invention, in a purified water production apparatus having a two-stage serial membrane separation means, it is possible to effectively clean the second-stage membrane separation means, which tends to have a lower cleaning effect than the first-stage membrane separation means, and to achieve excellent cleaning efficiency for the entire apparatus. [Brief description of the drawings]

[0015] [Figure 1] 1 is a flow diagram showing an example of the configuration of a purified water production apparatus of the present invention. [Diagram 2] FIG. 2 is a flow diagram showing a fresh water production process for producing purified water. [Diagram 3] FIG. 11 is a flow diagram showing a process for cleaning piping with a chemical solution. [Figure 4] FIG. 4 is a flow diagram showing a circulation flow path formed in a step of cleaning the first separation membrane module. [Diagram 5] FIG. 11 is a flow diagram showing a circulation flow path formed in a cleaning step of a second separation membrane module. [Figure 6] FIG. 11 is a flow diagram showing a state of parallel water flow in a simultaneous cleaning step of a first separation membrane module and a second separation membrane module. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Preferred embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a flow diagram showing the configuration of a purified water production apparatus 1 of the present invention, and FIG. 2 is a flow diagram showing a water production process for producing purified water. In the water production process for producing purified water, raw water flowing from a raw water source and stored in a raw water tank 2 is sent to a first membrane separation means consisting of a first pump 6 and a first separation membrane module 7 through a pretreatment means 11 consisting of a prefilter 3, a water softener 4, and an activated carbon filtration filter 5. The pretreated water is separated into a first permeate and a first concentrated water by the first membrane separation means, and the first concentrated water is discharged outside the system. The first permeate is separated into a second permeate and a second concentrated water by a second membrane separation means consisting of a second pump 8 and a second separation membrane module 9, and a part of the second concentrated water is returned to the raw water tank 2 and diluted with raw water, and reused for the production of purified water. The second permeate is stored in a permeate tank 10 and sent by a liquid delivery pump 18 through a liquid delivery line 19 to, for example, a dialysis fluid production device, where it is used as a diluent for the dialysis fluid.

[0017] 1, the purified water production apparatus 1 is provided with a bypass line 13 for bypassing the second separation membrane module 9 and sending the first permeated water directly to the permeated water tank 10, and a bypass valve 14 capable of opening and closing the bypass line 13. The permeated water tank 10 is also provided with a heating means 15. In the cleaning step for cleaning the inside of the system, the heating means 15 can be used to heat the stored second permeated water to produce hot water for disinfecting the inside of the system.

[0018] FIG. 3 is a flow diagram showing the chemical cleaning process of the piping. In the chemical cleaning process of the piping, which is performed at a predetermined frequency after the continuous freshwater production process, raw water flowing from the raw water source and stored in the raw water tank 2 is sent to the first membrane separation means consisting of the first pump 6 and the first separation membrane module 7 through the pretreatment means 11 consisting of the prefilter 3, the water softener 4, and the activated carbon filter 5. The pretreated water is separated into the first permeate and the first concentrated water by the first membrane separation means, and the first concentrated water is discharged outside the system. The first permeate flows into the permeate tank 10 through the bypass line 13 opened by the bypass valve 14, and the chemical injection means 12 provided between the first separation membrane module 7 and the bypass line 13 in the middle injects a cleaning chemical, so that the piping from the first separation membrane module 7 to the permeate tank 10 can be effectively cleaned with cleaning water containing a high concentration of cleaning chemical. The high concentration cleaning chemical is diluted with the second permeated water that was sent to and stored in the permeated water tank 10 in the fresh water production process. In this way, if the cleaning process for the separation membrane module is started with the permeated water tank 10 filled with the cleaning chemical dilution solution, it is possible to prevent the high concentration cleaning chemical from flowing into the separation membrane module even when cleaning a separation membrane module that has poor resistance to the cleaning chemical. In addition, by circulating and stirring the first cleaning water in the permeated water tank 10 with the liquid delivery pump 18, the high concentration cleaning chemical injected by the chemical injection means 12 can be sufficiently diluted.

[0019] 4 is a flow diagram showing the circulation flow path formed in the cleaning process of the first separation membrane module. The second permeate stored in the permeate tank 10 is sent as the first cleaning water by the first pump 6 through the first return line 16 to the first separation membrane module 7, and is separated into the permeation side and the concentrated side of the first separation membrane module 7 and flows out. The first cleaning water flowing out from the concentrated side is discharged outside the system, and the first cleaning water flowing out from the permeation side returns to the permeate tank 10 through the bypass line 13 opened by the bypass valve 14.

[0020] 5 is a flow diagram showing the circulation flow path formed in the cleaning process of the second separation membrane module. The second permeate stored in the permeate tank 10 is sent as second cleaning water by the second pump 8 through the second return line 17 to the second separation membrane module 9, and is separated into the permeation side and the concentrated side of the second separation membrane module 9 and flows out. The second cleaning water flowing out from the concentrated side is discharged outside the system, and the second cleaning water flowing out from the permeation side returns to the permeate tank 10.

[0021] 6, the cleaning step for the second separation membrane module 9 may be carried out simultaneously in parallel with the cleaning step for the first separation membrane module 7, so that the first cleaning water can also be used as the second cleaning water. Alternatively, the cleaning step for the second separation membrane module 9 may be carried out following the completion of the cleaning step for the first separation membrane module 7, so that the first cleaning water stored in the permeate tank 10 can be used as the second cleaning water. [Industrial Applicability]

[0022] The purified water producing apparatus of the present invention can be widely used in hemodialysis systems and other applications that use purified water. [Explanation of symbols]

[0023] 1 Purified water production equipment 2 Raw Water Tank 3 Pre-filter 4 water softener 5 Activated carbon filter 6. First Pump 7. First separation membrane module 8. Second Pump 9. Second separation membrane module 10 Permeate tank 11 Pretreatment means 12. Chemical injection means 13 Bypass Line 14 Bypass valve 15 Heating means 16 First Return Line 17 Second Return Line 18 Liquid delivery pump 19 Liquid delivery line

Claims

1. A pretreatment means for obtaining pretreated water from raw water; a first membrane separation means for separating the pretreated water into a first permeate and a first concentrate; a second membrane separation means for separating the first permeate into a second permeate and a second retentate; A permeate tank for storing the second permeate; a first return line for returning the second permeate upstream of the first membrane separation means; A first return valve capable of opening and closing the first return line; a second return line for returning the second permeate upstream of the second membrane separation means; A second return valve capable of opening and closing the second return line; a bypass line for sending the first permeate to the permeate tank, bypassing the second membrane separation means; A purified water production apparatus including a bypass valve capable of opening and closing the bypass line, A purified water production apparatus characterized in that purified water is produced with the first return line, the second return line and the bypass line closed, and the first membrane separation means and the second membrane separation means are cleaned with the bypass line open.

2. A pretreatment means for obtaining pretreated water from raw water; a first membrane separation means for separating the pretreated water into a first permeate and a first concentrate; a second membrane separation means for separating the first permeate into a second permeate and a second retentate; A permeate tank for storing the second permeate; a first return line for returning the second permeate upstream of the first membrane separation means; A first return valve capable of opening and closing the first return line; a second return line for returning the second permeate upstream of the second membrane separation means; A second return valve capable of opening and closing the second return line; a bypass line for sending the first permeate to the permeate tank, bypassing the second membrane separation means; A purified water production apparatus including a bypass valve capable of opening and closing the bypass line, A purified water production apparatus characterized in that purified water is produced with a first return line, a second return line and the bypass line closed, a first membrane separation means is cleaned by passing a first cleaning water through the bypass line and the first return line open, and a second membrane separation means is cleaned by passing a second cleaning water through the bypass line closed and the second return line open.

3. 3. The purified water producing apparatus according to claim 2, wherein the first cleaning water and / or the second cleaning water is hot disinfecting water obtained by heating the second permeated water in the permeated water tank.

4. 4. The purified water production apparatus according to claim 2 or 3, further comprising a cleaning chemical injection means for injecting a cleaning chemical into the first permeate line immediately downstream of the first membrane separation means, wherein the first cleaning water and / or the second cleaning water is a diluted cleaning chemical obtained by injecting the cleaning chemical into the first permeate.

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