CN110538576B

CN110538576B - Ultrafiltration membrane module and method for producing ultrapure water using ultrafiltration membrane module

Info

Publication number: CN110538576B
Application number: CN201910438933.1A
Authority: CN
Inventors: 野口幸男; 丹治辉
Original assignee: Nomura Micro Science Co Ltd
Current assignee: Nomura Micro Science Co Ltd
Priority date: 2018-05-28
Filing date: 2019-05-24
Publication date: 2023-02-28
Anticipated expiration: 2039-05-24
Also published as: CN110538576A

Abstract

The invention provides an ultrafiltration membrane module capable of remarkably reducing the concentration of trace ion components in ultrapure water, particularly in warm ultrapure water, and a method for producing ultrapure water. An ultrafiltration membrane module (10) comprising a plurality of hollow fiber membranes (1) formed by ultrafiltration membranes and a cylindrical case (2) accommodating the plurality of hollow fiber membranes (1), wherein the cylindrical case (2) is provided at the outer peripheral surface thereof with a 1 st nozzle (2 a) and a 2 nd nozzle (2 b) which are arranged separately from each other in the axial direction of the cylindrical case (2), into which treated water is introduced and from which concentrated water is discharged, a 3 rd nozzle (6 a) and a 4 th nozzle (6 b) which are arranged at both ends of the cylindrical case and from which permeated water and discharged water which have permeated through the hollow fiber membranes (1) are discharged, respectively, and a pair of fixing portions (3 a), (3 b) which fix the plurality of hollow fiber membranes (1) in a predetermined arrangement and seal the cylindrical case (2).

Description

Ultrafiltration membrane module and method for producing ultrapure water using ultrafiltration membrane module

Technical Field

The present invention relates to an ultrafiltration membrane module and a method for producing ultrapure water using the ultrafiltration membrane module.

Background

Ultrapure water used for the production of electronic and electric parts such as semiconductors and display elements has been conventionally produced using an ultrapure water production system. The ultrapure water production system is composed of, for example, a pretreatment unit for removing suspended substances in raw water to obtain pretreated water, a primary pure water production unit for producing primary pure water by removing Total Organic Carbon (TOC) components or ionic components in the pretreated water using a reverse osmosis membrane apparatus or an ion exchange apparatus, and a secondary pure water production unit for producing ultrapure water by removing very small amounts of impurities in the primary pure water. As the raw water, city water, well water, underground water, industrial water, and the like are used. As the raw water, used ultrapure water (hereinafter, referred to as "recovered water") recovered at a use site (use point: POU) of ultrapure water may be used.

In the secondary pure water production unit, the primary pure water is highly treated by an ultraviolet oxidation apparatus, an ion exchange pure water apparatus, an ultrafiltration membrane (UF) apparatus, and the like to produce ultrapure water. The ultrafiltration membrane apparatus is disposed in the vicinity of the final stage of the secondary pure water production section, and removes fine particles generated from an ion exchange resin or the like.

The ultrafiltration membrane device is configured by an ultrafiltration membrane module including a plurality of fiber bundles each including a hollow fiber-shaped ultrafiltration membrane accommodated in a cylindrical case, depending on the amount of collected water or the like. As the ultrafiltration membrane module, an external pressure type module in which raw water is supplied to the outside of a hollow fiber membrane is common, and there are a both-end water collection type ultrafiltration membrane module in which filtered water is collected from both ends, and a single-end water collection type ultrafiltration membrane module in which treated water is supplied from one end and filtered water is collected from the other end (see, for example, patent documents 1 and 2).

In the ultrafiltration membrane module, components of a chemical used in the production of the ultrafiltration membrane or components such as an adhesive or a potting agent used in the assembly of the ultrafiltration membrane into the module may be eluted during use to contaminate the permeated water. Therefore, a method for producing an ultrafiltration membrane module has been proposed which aims to easily clean the above-mentioned contaminants by cleaning the ultrafiltration membrane module before applying the method to ultrapure water production (for example, see patent document 3). As a potting agent for bonding and sealing the ultrafiltration membrane, a material with little elution of organic substances has also been proposed (for example, see patent document 4).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 7-96152

Patent document 2: international publication No. 2012/043679

Patent document 3: japanese patent laid-open No. 2001-129366

Patent document 4: japanese patent laid-open publication No. 2017-136548

Disclosure of Invention

Problems to be solved by the invention

However, in recent years, along with the miniaturization of semiconductor integrated circuits and the like, ultra-pure semiconductor devices have been developedThe number of water-containing laundry items (substances removed by washing) is also diversified, and the number of laundry items difficult to wash is increasing. Therefore, in order to improve the cleaning performance in semiconductor cleaning, warm ultrapure water or the like obtained by heating ultrapure water is also used. In addition, at present, the demand for high cleaning of the washing articles is becoming more stringent, and the demand for water quality of ultrapure water is also becoming more stringent. Among other things, the present inventors have recognized that: in ultrapure water supplied from a secondary pure water production unit of an ultrapure water production apparatus, an extremely small amount of ionic components (chloride ions (Cl)) remains ^- ) Etc.). It has been found that, particularly in the ultrapure water of a temperature at which the secondary pure water producing unit is circulated, the trace amount of the ionic component inhibits the quality of the ultrapure water from being improved. The trace ionic component was found to be a component of a chemical used in the production of the ultrafiltration membrane or a substance from which a component such as an adhesive or potting agent used in the assembly of the ultrafiltration membrane into a module eluted. However, an ultrafiltration membrane module which generates no or little elution substances under the conditions for producing warm ultrapure water (for example, 80 ℃) has not yet been put into the market. Therefore, development of an ultrafiltration membrane module in which generation of eluted substances is reduced has been demanded.

The present invention has been made in view of the above-described knowledge, and an object thereof is to provide an ultrafiltration membrane module capable of significantly reducing the concentration of trace ionic components in ultrapure water, particularly in warm ultrapure water, and a method for producing ultrapure water using the same.

Means for solving the problems

An ultrafiltration membrane module according to the present invention is an ultrafiltration membrane module including a plurality of hollow fiber membranes formed by an ultrafiltration membrane and a cylindrical casing accommodating the plurality of hollow fiber membranes, wherein the cylindrical casing includes, on an outer peripheral surface thereof, a 1 st nozzle and a 2 nd nozzle arranged to be spaced apart from each other in an axial direction of the cylindrical casing, a 3 rd nozzle and a 4 th nozzle arranged at both end portions of the cylindrical casing, and a pair of fixing portions for fixing the plurality of hollow fiber membranes in the axial direction of the cylindrical casing so that open ends of the plurality of hollow fiber membranes face the both end portions of the cylindrical casing, respectively, and sealing the cylindrical casing at positions between one end portion of the cylindrical casing and the 1 st nozzle and between the other end portion of the cylindrical casing and the 2 nd nozzle, the 1 st nozzle is a treated water inlet pipe for introducing treated water, the 2 nd nozzle is a concentrated water outlet pipe for allowing concentrated water that has not passed through the hollow fiber membranes to flow out, the 3 rd nozzle is a concentrated water outlet pipe for allowing concentrated water that has passed through the hollow fiber membranes to flow out, and the 4 th nozzle is a concentrated water outlet pipe for allowing concentrated water that has passed through the hollow fiber membranes to flow out.

In the ultrafiltration membrane module of the present invention, the permeated water outlet pipe is preferably provided closer to the concentrated water outlet pipe than the treated water inlet pipe.

In the ultrafiltration membrane module of the present invention, the fixing portion is preferably formed of an epoxy resin.

In the ultrafiltration membrane module of the present invention, the ratio of the amount of permeate flowing out from the permeate outflow pipe to the amount of permeate flowing out from the drain outflow pipe (the amount of permeate flowing out from the permeate outflow pipe/the amount of permeate flowing out from the drain outflow pipe) is preferably 90/10 to 99/1.

In an ultrafiltration membrane module comprising a plurality of hollow fiber membranes formed from an ultrafiltration membrane and a cylindrical housing accommodating the plurality of hollow fiber membranes, the cylindrical housing is provided at an outer peripheral surface thereof with a 1 st nozzle and a 2 nd nozzle arranged so as to be spaced apart from each other in an axial direction of the cylindrical housing, a 3 rd nozzle and a 4 th nozzle arranged at both end portions of the cylindrical housing, and a pair of fixing portions which fix the plurality of hollow fiber membranes in the axial direction of the cylindrical housing so that open ends of the plurality of hollow fiber membranes face the both end portions of the cylindrical housing, and seal the cylindrical housing at positions between one end portion of the cylindrical housing and the 1 st nozzle and between the other end portion of the cylindrical housing and the 2 nd nozzle, in the ultrafiltration module, treated water is introduced into the ultrafiltration membrane module from the 1 st nozzle, concentrated water which has not permeated through the hollow fiber membranes is discharged from the 2 nd nozzle, and water which has permeated through the hollow fiber membranes is discharged from the 3 rd nozzle of the cylindrical housing as permeated water.

In the method for producing ultrapure water of the present invention, chloride ions (Cl) in the water to be treated are contained ^- ) The concentration is preferably 0.01. Mu.g/L to 2. Mu.g/L (in Cl).

In the method for producing ultrapure water of the present invention, chloride ions (Cl) in the water to be treated ^- ) The concentration is preferably 1ng/L or less (as Cl).

In the method for producing ultrapure water of the present invention, chloride ions (Cl) in the permeated water of the ultrafiltration membrane module ^- ) The concentration is preferably 5ng/L or less (as Cl).

In this specification, the term "to" represents a numerical range including numerical values on both sides thereof.

Effects of the invention

According to the ultrafiltration membrane module of the present invention, the concentration of trace ionic components can be significantly reduced in the case of producing ultrapure water, particularly warm ultrapure water by treating water to be treated.

According to the method for producing ultrapure water of the present invention, ultrapure water suitable for significantly reducing trace ion components, particularly ultrapure water suitable for warm ultrapure water, can be obtained.

Drawings

Fig. 1 is a sectional view schematically showing an ultrafiltration membrane module according to embodiment 1.

FIG. 2 is a block diagram schematically showing an ultrapure water production system according to embodiment 1.

Fig. 3 is a block diagram schematically showing a modification of the ultrapure water production system according to embodiment 1.

Fig. 4 is a diagram showing a schematic configuration of an ultrafiltration membrane apparatus in the ultrapure water production system according to embodiment 2.

Fig. 5 is a view showing a schematic configuration of another ultrafiltration membrane apparatus in the ultrapure water production system of embodiment 2.

Fig. 6 is a graph showing changes with time in the chloride ion concentration in the permeated water in example 1 and comparative example.

FIG. 7 is a graph showing the relationship between the flow rate ratio of permeated water discharged and the chloride ion concentration in the permeated water in example 2.

Description of the symbols

1. A hollow fiber membrane,

2. A cylindrical housing,

2a and 2b nozzles,

3a, 3b fixing parts,

4. A Heat Exchanger (HEX),

6a and 6b nozzles,

60a, 60b piping connection caps,

61a, 61b contact portions,

101. A concentrated water pipe,

102. A water discharge pipe,

103. A water pipe to be treated,

104 through a water pipe,

V1 and V2 valves,

11. A pretreatment section,

12. A primary pure water producing section,

13. A secondary pure water producing section,

14. A pot,

34. 41 Heat Exchanger (HEX),

35. Ultraviolet ray oxidation apparatus (TOC-UV),

36. Hydrogen peroxide removal device (H) ₂ O ₂ Removing means)

37. A degassing membrane device,

38. Non-regenerative mixed bed type ion exchange resin,

30. 40 an ultrafiltration membrane device,

50. 51 Point of use (POU),

100. An ultrapure water production system,

And (P) a pump.

Detailed Description

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

(embodiment 1)

An ultrafiltration membrane module 10 of the present embodiment shown in fig. 1 includes a plurality of hollow fiber membranes 1, a cylindrical case 2 accommodating the hollow fiber membranes 1, and a pair of fixing

portions

3a and 3b for fixing both end portions of the hollow fiber membranes 1 in the cylindrical case. The ultrafiltration membrane module 10 includes pipe connection caps 60a and

60b having nozzles

6a and 6b at both ends of the cylindrical casing 2, respectively. Grooves are formed in the abutting

portions

61a and 61b of the pipe connection cap with the end portion of the cylindrical case 2, respectively, and the pipe connection cap is attached to the cylindrical case 2 by an unillustrated acoustic ring disposed in the groove and a nut (not shown) that covers and fixes a part of the pipe connection cap to the end portion of the cylindrical case 2.

The cylindrical housing 2 includes

nozzles

2a and 2b on its outer peripheral surface. The

nozzles

2a and 2b are arranged on the outer peripheral surface of the cylindrical case 2 so as to be spaced apart from each other in the axial direction of the cylindrical case 2. In fig. 1, the

nozzles

6a and 6b may be arranged in opposite positions, but as shown in fig. 1, the nozzle 6b is preferably arranged closer to the nozzle 2b than the nozzle 2 a.

The hollow fiber membrane 1 is, for example, a fiber bundle in which a plurality of hollow fiber membranes are collected into one bundle. Alternatively, the hollow fiber membranes 1 may be membranes that are divided into small bundles in which some of the plurality of hollow fiber membranes housed in the cylindrical case 2 are collected and the small bundles are collected. The fiber bundles or small bundles of the hollow fiber membranes 1 may be entirely wrapped with a net or nonwoven fabric made of polypropylene. By collecting the hollow fiber membranes into a fiber bundle and disposing the fiber bundle in the cylindrical case 2, a portion not filled with the hollow fiber membranes 1 (a portion having a low membrane packing density) is formed between the hollow fiber membranes 1 in the cylindrical case 2 and the inner peripheral surface of the cylindrical case 2, whereby the resistance of water flowing outside the hollow fiber membranes 1 is reduced, and a higher water permeability of the module can be achieved.

As the hollow fiber membrane 1, an ultrafiltration membrane is used. The ultrafiltration membrane preferably has a fractional molecular weight of 4000 to 6000 and an effective membrane area of 10m ² ～35m ² The design operating differential pressure is preferably 0.1MPa to 0.4MPa. In addition, regarding the fine particle removal performance of the ultrafiltration membrane, the removal rate of fine particles having a particle diameter of 20nm or more is preferably 65% or more. The operating differential pressure was designed to be an operating differential pressure (permeate pressure) at which the rejection of impurities in the ultrafiltration membrane reached a maximum value of 90% of the maximum valueThe difference between the pressure of the water and the pressure of the feed water). The design operating pressure difference may be a value in a table of a standard operating pressure of the ultrafiltration membrane and the like, which is publicly known by a manufacturer.

The material of the hollow fiber membrane may be appropriately selected depending on the application, and may be selected from, for example, polyethylene, polypropylene, polysulfone, polyethersulfone, polyvinylidene fluoride, polyvinyl alcohol, cellulose acetate, and polyacrylonitrile.

The inner diameter of the hollow fiber membrane is preferably 0.50 to 1.0mm, particularly preferably 0.70 to 0.85mm.

The cylindrical case 2 is formed of a cylindrical member having openings at both ends. The cylindrical case 2 has

nozzles

2a and 2b provided near interfaces Fa and Fb of the fixing

portions

3a and 3b. The interface of the fixing portion is a surface of the fixing portion on the side of the cylindrical case 2 in which the hollow fiber membranes 1 are accommodated. The material of the cylindrical case 2 can be selected from metals and plastics as appropriate depending on the application. The cylindrical case 2 is preferably formed of plastic from the viewpoints of ease of processing and weight reduction. Examples of the material of the cylindrical case 2 include polyethylene, polypropylene, polysulfone, polyethersulfone, polyvinylidene fluoride, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), and vinyl chloride resin. The number of nozzles provided near the interfaces Fa and Fb is not necessarily 1, and a plurality of nozzles may be provided near the interfaces Fa and Fb.

The size of the cylindrical casing 2 may be appropriately selected depending on the amount of water to be treated, and as an example, the outer diameter is preferably 140 to 200mm and the length is preferably 700 to 1400mm, and the outer diameter is particularly preferably 160 to 180mm and the length is preferably 800 to 1200mm. When the cylindrical casing 2 having a size within this range is used, high module water permeability and the highest module water permeability can be achieved. Further, the above size provides an advantage that the ultrafiltration membrane module 10 can be lifted by 1 person, and thus the handling property is particularly excellent. The "outer diameter" of the cylindrical casing 2 refers to the outer diameter of the cylinder in the central filtration region of the ultrafiltration membrane module 10. The "length" of the cylindrical case 2 means a distance between both end faces of the hollow fiber membrane.

The fixing

portions

3a and 3b seal gaps between the outer surfaces of the hollow fiber membranes 1 and between the outer surfaces and the inner surface of the cylindrical case 2 at both ends of the hollow fiber membranes 1 in the cylindrical case 2. The hollow fiber membranes 1 are fixed by the fixing

portions

3a and 3b along the axial direction (longitudinal direction) of the cylindrical case 2, and the open ends of the hollow portions of the hollow fiber membranes 1 are exposed at both end portions of the cylindrical case 2. Upon water treatment, the permeated water flows out from the open end.

As a material of the fixing

portions

3a and 3b, a thermosetting resin such as an epoxy resin or a urethane resin is used. As the material of the fixing

portions

3a and 3b, epoxy resin is preferable in terms of less elution. Examples of the epoxy resin include bisphenol a type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, novolak type epoxy resin, bisphenol a novolak type epoxy resin, trihydroxymethane type epoxy resin, tetraphenylolethane type epoxy resin, tetraglycidyldiaminodiphenylmethane type epoxy resin, aminophenol type epoxy resin, aniline type epoxy resin, benzylamine type epoxy resin, and xylylenediamine type epoxy resin.

The material of the fixing

portions

3a and 3b is selected according to the material of the hollow fiber membrane 1, the adhesion to the hollow fiber membrane 1, the strength of the hollow fiber membrane 1, and the like. The material of the fixing

portions

3a and 3b is preferably a material having a small elution component. Specifically, as an example of the material, it is preferable that the effective membrane area of the hollow fiber membrane 1 is 34m ² And a hollow fiber membrane module having an outer diameter of 160 to 180mm and a length of 800 to 1200mm, wherein the hollow fiber membrane module is used in a state of being contacted with warm pure water at about 70 to 80 ℃, the elution amount of chloride ions eluted into the whole permeated water is 10ng/L or less, preferably 6ng/L or less. By using a material in which elution of an organic component is suppressed as the material of the fixing

portions

3a and 3b, elution of an organic component can be suppressed.

The ultrafiltration membrane module 10 of the present embodiment may have a pair of rectifying tubes extending from the positions of the interfaces Fa and Fb of the fixing

portions

3a and 3b toward the center of the module 10. If the flow-straightening cylinders surrounding the fixing

portions

3a and 3b and the both end portions of the hollow fiber membrane 1 are provided, the hollow fiber membrane can be effectively prevented from being damaged in the vicinity of the interfaces Fa and Fb.

Pipes are connected to the

nozzles

2a and 2b and the

nozzles

6a and 6b of the ultrafiltration membrane module 10 of the present embodiment, and supply of the water to be treated, collection of the permeated water, and discharge of the concentrated water are performed. In the ultrafiltration membrane module 10, for example, the nozzle 2a is set as a treated water inlet pipe (nozzle 1), and the nozzle 2b is set as a concentrated water outlet pipe (nozzle 2). The nozzle 6a is set as a discharge water outlet pipe (nozzle No. 4), and the nozzle 6b is set as a permeated water outlet pipe (nozzle No. 3). For example, a concentrated water pipe 101 having a valve V1 with a variable opening degree is connected to the nozzle 2b (concentrated water outflow pipe), and a discharge water pipe 102 having a valve V2 with a variable opening degree is connected to the nozzle 6a (discharge water outflow pipe). The water pipe 103 to be treated is connected to the nozzle 2a (water inlet pipe to be treated), and the water pipe 104 is connected to the nozzle 6b (water outlet pipe).

The water to be treated is introduced into the ultrafiltration membrane module 10 from the nozzle 2a, and is subjected to filtration treatment while flowing from the outside to the inside of the hollow fiber membrane, and the concentrated water flows out from the nozzle 2b, and the permeated water flows out from the nozzle 6b which is a permeated water outflow pipe. Further, a part of the permeated water flows out as discharged water from a nozzle 6a as a discharged water outflow pipe.

As the water to be treated, water obtained by removing ionic components, nonionic components, dissolved gases, and fine particles from raw water by ion exchange treatment, degassing treatment, ultraviolet oxidation treatment, ultrafiltration, microfiltration, or the like can be used. The water to be treated is generally referred to as primary pure water or pure water, and examples thereof include water having a TOC (total organic carbon) concentration of 5 μ gC/L or less and a specific resistivity of 17M Ω · cm or more. Further, as for the amount of ionic components in the water to be treated, for example, chloride ions (Cl) ^- ) The concentration was 0.01. Mu.g/L to 2. Mu.g/L (in terms of Cl, the same applies hereinafter). ) Preferably, it is 0.01. Mu.g/L to 0.1. Mu.g/L.

The temperature of the water to be treated is preferably 10 to 90 ℃ and more preferably 20 to 80 ℃. Since the amount of the eluted substances from the fixed

parts

3a and 3b tends to increase when hot water having a high temperature is used as the water to be treated, a great effect of suppressing the eluted substances can be easily obtained by setting the temperature range.

According to the ultrafiltration membrane module 10 of the above embodiment, the permeated water with significantly reduced ionic components is obtained from the nozzle 6 b. This is considered to be for the following reason. In the both-end water collection type ultrafiltration membrane module, the permeated water generated in the ultrafiltration membrane module flows out from the

nozzles

6a and 6b through contact with the fixing

portions

3a and 3b provided in the vicinity of both ends of the cylindrical casing. And (3) presuming: when the permeated water comes into contact with the fixing

portions

3a and 3b, components eluted from the material of the fixing

portions

3a and 3b are mixed into the permeated water to cause contamination. The eluted component is specifically an organic component or chloride ion (Cl) ^- ) Plasma component. The higher the water temperature, the more the eluted components tend to increase.

In contrast, in the ultrafiltration membrane module 10 of the present embodiment, a part of the permeated water generated in the ultrafiltration membrane module flows out from the nozzle 6b and is used as ultrapure water. At this time, the permeated water comes into contact with the fixing portion 3b provided in the vicinity of one end portion of the cylindrical case 2. The amount of components eluted from the material of the fixing portion 3b is preferably half of the amount of components eluted from the material of the fixing

portions

3a and 3b. The remaining part of the permeated water generated in the ultrafiltration membrane module is discharged from the nozzle 6a as the effluent which is not used as ultrapure water. This reduces the contamination of the eluted components into the permeated water.

In fact, even if the amounts of elution from the

nozzles

6a and 6b are made equal, the amounts of elution components in the discharged water and the permeated water flowing from both of them do not always become equal. For example, in addition to the flow rate and water recovery rate of the water to be treated, the amount of migration of components eluted from the material of the fixed

portions

3a and 3b into the permeated water can be reduced by adjusting the opening degree of the valve V2 interposed in the water discharge pipe 102 and adjusting the ratio of the amount of outflow from the

nozzles

6a and 6b according to the size of the ultrafiltration membrane module 10. According to the ultrafiltration membrane module 10 having the above-described configuration, even when water to be treated having a water passage temperature of 70 to 80 ℃ is passed through, for example, the chloride ions (Cl) can be obtained from the nozzle 6b ^- ) The concentration is 5ng/L or less, more preferably 1ng or lessThe lower permeate water was used as ultrapure water. In addition, it is considered that: the chloride ion concentration in the permeated water was reduced to about 0.1ng, although it varied depending on the lower limit of the quantification by the measuring instrument.

For example, the outflow rate from the nozzle 6a (discharge water outflow pipe) and the nozzle 6b (permeate outflow pipe) is equal to the outflow rate L from the nozzle 6b _t (cm ³ Per hour) relative to the outflow L from the nozzle 6a _c (cm ³ Per hour) value L _t /L _c The ratio is preferably 90/10 to 99/1, more preferably 95/5 to 98/2. Value L of the ratio of outflow _t /L _c This can be done by adjusting the opening of the valve V2. Further, the value L of the outflow rate ratio may be adjusted by making the inner diameter of the discharged water outflow pipe smaller than the inner diameter of the permeated water outflow pipe _t /L _c . If L is _t /L _c Within the above range, the amount of eluted ionic components in the permeated water is easily reduced.

In the ultrafiltration membrane module 10 of the present embodiment, the water recovery rate is preferably 90% or more, and more preferably 95% or more. The operating differential pressure in the ultrafiltration membrane module 10 is preferably 0.1 to 0.4MPa. This can reduce the retention of water in the ultrafiltration membrane module, and therefore can reduce the amount of elution components that migrate into the permeated water.

Next, an ultrapure water production system 100 using the ultrafiltration membrane module according to the above-described embodiment will be described with reference to fig. 2.

The ultrapure water production system 100 shown in FIG. 2 comprises a pretreatment unit 11, a primary pure water production unit 12, and a secondary pure water production unit 13. A tank 14 is connected between the primary pure water production unit 12 and the secondary pure water production unit 13.

The pretreatment unit 11 removes suspended matter in the raw water to generate pretreatment water, and supplies the pretreatment water to the primary pure water production unit 12. The pretreatment unit 11 is configured by appropriately selecting, for example, a sand filter device, a microfiltration device, and the like for removing suspended substances in raw water, and further includes, as necessary, a heat exchanger for adjusting the temperature of raw water, and the like. The pretreatment unit 11 may be omitted depending on the quality of the raw water.

The raw water is, for example, water (recovered water) used in city water, well water, underground water, industrial water, semiconductor manufacturing plants, and the like, recovered, and pretreated.

The primary pure water production unit 12 is configured by appropriately combining 1 or more of a reverse osmosis membrane device, a degasifier (e.g., decarbonation, a vacuum degasifier, and a degasifier), an ion exchanger (e.g., a cation exchange resin device, an anion exchange resin device, a mixed-bed ion exchange resin device, and an electrodeionization device), and an ultraviolet oxidizer. The primary pure water production unit 12 removes ionic components, nonionic components, and dissolved gases in the pretreatment water to produce primary pure water, and supplies the primary pure water to the tank 14. The primary pure water has a Total Organic Carbon (TOC) concentration of 5 [ mu ] gC/L or less and a resistivity of 17M [ omega ] cm or more.

As the primary pure water producing unit, for example, a configuration may be used in which a strong base anion exchange resin apparatus, a 2B3T type apparatus (a strong acid cation exchange resin apparatus, a decarbonation acid column, a basic anion exchange apparatus), a reverse osmosis membrane apparatus, an ultraviolet oxidation apparatus, a mixed bed type ion exchange resin apparatus, and a degassing membrane apparatus are provided in this order.

Tank 14 stores pure water once. The necessary amount is supplied to the secondary pure water production unit 13 by the pump P.

The secondary pure water production unit 13 removes a small amount of impurities from the primary pure water to produce ultrapure water. As shown in fig. 2, the secondary pure water production unit 13 includes a Heat Exchanger (HEX) 34, an ultraviolet oxidation device (TOC-UV) 35, and a hydrogen peroxide removal device (H) on the upstream side of the ultrafiltration membrane device 30 ₂ O ₂ Removal apparatus) 36, a degassing membrane apparatus (MDG) 37, and a non-regenerative mixed bed ion exchange resin apparatus (Polisher) 38. The secondary pure water production unit 13 does not necessarily need to have the above-described devices, and the above-described devices may be combined as necessary.

The pump P pressurizes the primary pure water supplied from the tank 14 and supplies the pressurized water to the Heat Exchanger (HEX) 34. The heat exchanger 34 adjusts the temperature of the primary pure water supplied from the tank 14 as necessary. The temperature of the primary pure water after the temperature adjustment by the heat exchanger 34 is preferably 20 to 30 c, and more preferably 22 to 25 c.

An ultraviolet oxidation apparatus (TOC-UV) 35 irradiates the primary pure water whose temperature has been adjusted by the heat exchanger 34 with ultraviolet rays to decompose and remove a trace amount of organic substances in the water. The ultraviolet oxidation device 35 has, for example, an ultraviolet lamp and generates ultraviolet rays having a wavelength of about 185 nm. The ultraviolet oxidation device 35 may further generate ultraviolet rays having a wavelength of around 254 nm. When water is irradiated with ultraviolet rays in the ultraviolet oxidation device 35, the ultraviolet rays decompose the water to generate OH radicals, which oxidize and decompose organic substances in the water. In order to suppress deterioration of the ultrafiltration membrane of the downstream ultrafiltration membrane apparatus 30, the ultraviolet ray irradiation amount in the ultraviolet ray oxidation apparatus 35 is preferably 0.05 to 0.2kWh/m ³ 。

Hydrogen peroxide removal device (H) ₂ O ₂ Removal device) 36 is a device for decomposing and removing hydrogen peroxide in water, and is, for example, a palladium (Pd) -supported resin device for decomposing and removing hydrogen peroxide by a Pd-supported resin, a reducing resin device filled with a reducing resin having a sulfurous acid group and/or a sulfurous acid hydrogen group on the surface, or the like. Since the hydrogen peroxide in the water can be reduced by providing the hydrogen peroxide removal device 36, deterioration of the ultrafiltration membrane device 30 and the second ultrafiltration membrane device 40 described later can be suppressed.

The degassing membrane unit (MDG) 37 is a unit that depressurizes the secondary side of the gas permeable membrane and removes only dissolved gas in water flowing through the primary side by allowing the gas to permeate the secondary side. As the degassing membrane unit 37, commercially available products such as X-50, X40 manufactured by 3M company, and Separel manufactured by DIC company can be specifically used. The degassing membrane apparatus 37 removes dissolved oxygen from the treatment water in the hydrogen peroxide removal apparatus 36 to produce treatment water having a dissolved oxygen concentration (DO) of, for example, 1 μ g/L or less.

The non-regenerative mixed bed ion exchange resin device (Polisher) 38 has a mixed bed ion exchange resin in which a cation exchange resin and an anion exchange resin are mixed, and adsorbs and removes a small amount of cation components and anion components in the treated water in the degassing membrane device 37.

Examples of the cation exchange resin included in the non-regenerative mixed bed type ion exchange resin apparatus 38 include a strongly acidic cation exchange resin and a weakly acidic cation exchange resin, and examples of the anion exchange resin include a strongly basic anion exchange resin and a weakly basic anion exchange resin. As commercially available products of the mixed bed type ion exchange resin, for example, N-Lite MBSP, MBGP, etc. manufactured by Nomura Micro Science Co., ltd.

The ultrafiltration membrane apparatus 30 includes the ultrafiltration membrane module 10 according to the above embodiment. The ultrafiltration membrane apparatus 30 treats the treated water of the non-regenerative mixed bed ion exchange resin apparatus 38 to produce permeate water, concentrate water, and drain water. In the ultrafiltration membrane apparatus 30, the removal rate of fine particles having a particle diameter of 20nm or more is preferably 99.8% or more, more preferably 99.95% or more, and further preferably 99.99% or more. Thus, most of the fine particles causing deterioration of the quality of ultrapure water are removed by the ultrafiltration membrane apparatus 30, and the number of fine particles having a particle diameter of 50nm or more is 500/L or less, and further 200/L or less, for example, of the permeated water. The permeated water produced in the ultrafiltration membrane apparatus 30 is supplied to a use place (use point: POU) 50 of ultrapure water. The concentrated water is discharged outside the system or circulated in the front stage of the ultrapure water production system 100 and is reprocessed.

In the ultrapure water production system of the present embodiment, since chlorine is adsorbed and removed by the non-regenerative mixed bed type ion exchange resin apparatus 38, the chloride ion concentration in the supply water to the ultrafiltration membrane apparatus 30 can be set to, for example, 5ng/L or less.

According to the ultrapure water production system 100 described above, since the ultrafiltration membrane apparatus 30 including the ultrafiltration membrane module 10 according to the present embodiment is disposed at the most downstream side of the secondary pure water production unit 13, elution of contaminants from the ultrafiltration membrane module is significantly suppressed. Therefore, ultrapure water with a significantly reduced chloride ion plasma component can be obtained.

As shown in fig. 3, a 2 nd heat exchanger (HEX 2) 41 and a 2 nd ultrafiltration membrane apparatus (UF 2) 40 including the ultrafiltration membrane module 10 of the above embodiment may be further disposed in this order at a later stage of the ultrafiltration membrane apparatus 30 of the ultrapure water production system 100 shown in fig. 2. In this case, for example, a branch pipe may be connected to the permeated water outflow pipe of the ultrafiltration membrane apparatus 30, the 2 nd heat exchanger 41 and the 2 nd ultrafiltration membrane apparatus 40 may be disposed on the path of the branch pipe, and a part of the permeated water (ultrapure water) obtained by the ultrafiltration membrane apparatus 30 may be sequentially passed through the 2 nd heat exchanger 41 and the 2 nd ultrafiltration membrane apparatus (UF 2) 40.

When the 2 nd heat exchanger 41 and the 2 nd ultrafiltration membrane apparatus 40 are used, the 2 nd heat exchanger 41 preferably heats the treated water in the ultrafiltration membrane apparatus 30 to 70 to 90 ℃ and supplies the heated water to the 2 nd ultrafiltration membrane apparatus 40. As the 2 nd ultrafiltration membrane apparatus 40, an apparatus having the same specification as that of the above ultrafiltration membrane apparatus 30 may be used, or an apparatus having a different specification may be used. Thereby, for example, warm ultrapure water heated to 70 to 90 ℃ can be obtained. The permeated water produced in the 2 nd ultrafiltration membrane apparatus 40 is supplied to a place (point of use: POU) 51 where the warm ultrapure water is used. In this case, without using the method of the present invention, the amount of components (contaminants) eluted from the ultrafiltration membrane module by the warm ultrapure water tends to increase, but since the ultrafiltration membrane module of the embodiment is used, a great effect is obtained that ultrapure water in which the chloride ion plasma component is significantly reduced can be obtained. In the case where the 2 nd ultrafiltration membrane apparatus 40 is disposed, if the ultrafiltration membrane module of the above embodiment is used in the 2 nd ultrafiltration membrane apparatus 40, the ultrafiltration membrane module of the above embodiment may be used in the 1 st ultrafiltration membrane apparatus 30, or a conventional water collection type ultrafiltration membrane module at both ends may be used.

By suppressing the increase due to the passage of the hot pure water through the ultrafiltration membrane apparatus 40, the chloride ion concentration in the permeated water (ultrapure water) of the ultrafiltration membrane apparatus 40 can be maintained at, for example, 5ng/L or less, more preferably 1ng or less. The number of fine particles having a particle diameter of 50nm or more in the permeate of the ultrafiltration membrane apparatus 40 is, for example, 200/L or less, preferably 50/L or less.

(embodiment 2)

Next, embodiment 2 of the present invention will be explained.

The ultrafiltration membrane apparatus and the method for producing ultrapure water according to embodiment 2 basically have the same configuration as that of the ultrafiltration membrane module described in embodiment 1, but differ only in that the ultrafiltration membrane module used in the ultrafiltration membrane apparatus 30 has a 2-stage configuration in which two ultrafiltration membrane modules are connected. That is, as shown in fig. 4, the first ultrafiltration membrane module 30a and the second ultrafiltration membrane module 10 may be connected to each other, or as shown in fig. 5, the ultrafiltration membrane modules 10 according to the present embodiment may be used as both the first ultrafiltration membrane module and the second ultrafiltration membrane module and connected to each other.

The first ultrafiltration membrane module 30a shown in fig. 4 may be any conventionally known ultrafiltration membrane module without any particular limitation, but here, a case where a conventional ultrafiltration membrane module of the water collection type at both ends is used is exemplified. This ultrafiltration membrane module 30a has

nozzles

32a and 32b and nozzles 36a and 36b, and houses a hollow fiber membrane formed of an ultrafiltration membrane inside. The water to be treated is introduced into the ultrafiltration membrane module 30a from the nozzle 32a connected to the water to be treated inlet pipe 113 through which the water to be treated supplied to the ultrafiltration membrane device 30 flows, and the concentrated water that has not permeated through the ultrafiltration membrane flows out from the concentrated water outlet pipe 111 connected to the nozzle 32 b. On the other hand, the permeated water having passed through the ultrafiltration membranes flows out from the permeated water outlet pipes 114 connected to the nozzles 36b provided at both ends, and after all of them are merged, the water to be treated as the 2 nd ultrafiltration membrane module 10 is introduced into the 2 nd ultrafiltration membrane module 10 from the nozzle 2a connected to the water pipe 103 to be treated.

The process in the 2 nd ultrafiltration membrane module is as described in embodiment 1. In the 2 nd ultrafiltration membrane module, the concentrated water may be discharged, but the valve V1 may be closed to set the total amount of filtration.

Fig. 5 illustrates a case where two ultrafiltration membrane modules according to the present embodiment are used. Here, the 1 st and 2 nd

ultrafiltration membrane modules

10A and 10B are both the ultrafiltration membrane modules 10 of the present embodiment described above, and the flow of the water to be treated is as described above, the water to be treated is introduced from the

water pipes

103A and 103B to be treated, the concentrated water flows out from the concentrated water pipes 101A and 101B, the drain water flows out from the

drain water pipes

102A and 102B, and the permeated water flows out from the permeated

water pipes

104A and 104B. In the present embodiment, the permeated water that has passed through the ultrafiltration membrane of the first ultrafiltration membrane module 10A flows out from the permeated water pipe 104A connected to the nozzle 6B, and is directly introduced as the water to be treated of the second ultrafiltration membrane module 10B into the second ultrafiltration membrane module from the nozzle 2a connected to the treated water pipe 103B. As described above with reference to fig. 4, in the configuration of fig. 5, the concentrated water may be discharged by the treatment in the 2 nd ultrafiltration membrane module, but the valve V1 may be closed to set the total volume filtration.

By setting the configuration as shown in fig. 4 and 5, most of the fine particles are removed by the 1 st ultrafiltration membrane module, and the load of the fine particles on the 2 nd ultrafiltration membrane module is almost eliminated, so that the operation can be performed with the total amount of filtration. By setting the total amount of filtration, the recovery rate can be improved, and further, fiber breakage of the hollow fiber membranes housed in the ultrafiltration membrane module can be suppressed.

In this embodiment, since the ultrafiltration membrane module is configured to have 2 stages as described above and the 2 nd ultrafiltration membrane module is the ultrafiltration membrane module described in embodiment 1, a great effect of obtaining ultrapure water in which the chloride ion plasma component is significantly reduced can be obtained.

In fig. 4 and 5, the ultrafiltration membrane module 10 of the present embodiment used as the 2 nd ultrafiltration module may be used so as to stand upright with the nozzle 6a side positioned in the vertical direction (downward).

In this case, the water to be treated is introduced from the nozzle 2a which is a lower introduction pipe of the 2 nd outside restriction module 10, the permeated water having permeated through the hollow fiber membranes is obtained from the nozzle 6b in the vertical direction (upper direction), and the discharged water is made to flow out from the nozzle 6a in the vertical direction (lower direction) after having permeated through the hollow fiber membranes. The concentrated water that has not passed through the hollow fiber membranes may flow out from the nozzles 2b, but may be filtered in its entire amount without flowing out as described above.

The effect of performing the total amount filtration is similar to the above, and the fiber breakage can be suppressed, and the following effect can be further exhibited. When the 2 nd ultrafiltration module 10 is set to be erected, even if a fiber breakage of the hollow fiber membrane occurs, the fiber breakage is likely to occur at the interface Fa of the fixed portion on the nozzle 2a side into which the water to be treated is introduced. In this case, the occurrence of fiber breakage occurs below, i.e., on the outflow side of the discharged water. Therefore, the problematic water to be treated flows out from the nozzles 6a in the vertical direction (lower side) of the 2 nd ultrafiltration membrane module, and the quality of the treated water can be stably ensured without affecting the treated water flowing out from the nozzles 6b in the vertical direction (upper side).

Examples

Next, examples will be described. The present invention is not limited to the following examples.

(production of Warm pure Water)

Water treatment was performed as follows using an external pressure type double-side water collection type ultrafiltration membrane module (OLT-6036 VA manufactured by Asahi Kasei corporation). The external pressure type ultrafiltration membrane module of the water collection type at both ends used in this example has a three-dimensional structure similar to that of fig. 1, and is designed such that water to be treated is introduced from the nozzle 2a, concentrated water flows out from the nozzle 2b, and permeated water is collected from both the nozzle 6a and the nozzle 6 b.

The specification of OLT-6036VA manufactured by Asahi Kasei corporation is as follows.

The inner diameter of the hollow fiber membrane is 0.6mm

The effective membrane area is 34m ²

The inner diameter of the assembly (cylindrical housing) was 172mm

The length of the assembly (cylindrical housing) was 1177mm

Nominal fractional molecular weight of ultra-filtration membrane is 6000

The highest differential pressure between the inner surface and the outer surface of the membrane was 300kPa (25 ℃ C.)

An ultrapure water production system having a secondary pure water production unit 13 similar to the ultrapure water production system shown in FIG. 3 was used. The secondary pure water producing unit includes a 1 st heat exchanger, an ultraviolet oxidation device (manufactured by PHOTOSCIENCE JAPAN CORP., JPW-2), a palladium (Pd) supported resin device (manufactured by LANXESS, lewatit K7333), a degassing membrane device (manufactured by 3M, X40G 451H), a non-regenerative mixed bed ion exchange device (200L Nomura Micro Science Co., manufactured by Ltd., N-Lite MBSP), the ultrafiltration membrane device (manufactured by Asahi chemical Co., ltd., OLT-6036 VA), and a 2 nd heat exchanger in this order downstream of a tank for storing primary pure water. The temperature of the primary pure water was adjusted to 23. + -. 3 ℃ in the 1 st heat exchanger, and the permeate water of the ultrafiltration membrane apparatus was heated to 80 ℃ in the 2 nd heat exchanger. In the ultrafiltration membrane module provided in the ultrafiltration membrane apparatus used for producing the warm pure water, the permeated water is collected by collecting water at both ends. The obtained warm pure water had a specific resistivity of 17 M.OMEGA.cm or more, a TOC concentration of 5. Mu.gC/L or less, a number of fine particles having a particle diameter of 50 μ M or more of about 200/L, and a chloride ion concentration of 25ng/L.

(example 1)

The ultrafiltration membrane module having substantially the same structure as the external pressure type ultrafiltration membrane module of the both-end water collection type, in which the permeate water was caused to flow out from the nozzle 6b and the drain water was caused to flow out from the nozzle 6a and collected on one side, was used, and the obtained warm pure water (pure water heated to 80 ℃) was introduced into the ultrafiltration membrane module from the nozzle 2a disposed on the side surface of the cylindrical casing, and subjected to filtration treatment by the external pressure type. According to the outflow volume of the concentrated water from the nozzle 2b relative to the flow volume (m) of the primary pure water supplied from the nozzle 2a ³ Hour) to 3%. The opening degree of the valve V2 is set so that the flow rate of the effluent from the nozzle 6a becomes 2% and the amount of the permeated water collected from the nozzle 6b becomes 98% of the total flow rate of the effluent from the

nozzles

6a and 6b in the water having passed through the ultrafiltration membrane.

The ultrafiltration membrane module is used so as to be upright with the nozzle 6a side positioned in the vertical direction (downward). The chloride ion concentration (in Cl) in the permeated water was measured with respect to the time from the start of the supply of warm pure water into the ultrafiltration membrane module. The results are shown in table 1. The chloride ion concentration was measured by ion chromatography (Dionex ICS-5000, manufactured by Thermo Fisher Scientific Co., ltd.).

Comparative example

The warm pure water (pure water heated to 80 ℃) obtained above was introduced into the ultrafiltration membrane module from the nozzle 2a in the same manner as in example 1 using the external-pressure type both-end water collection type ultrafiltration membrane module. However, the concentrated water flowed out from the nozzle 2b at the same flow rate as in example 1 (the outflow rate of the concentrated water was 3% with respect to the flow rate of the supplied primary pure water), and the permeated water was collected from both the

nozzles

6a and 6b disposed at both ends of the ultrafiltration membrane module. Similarly to example 1, the change with time of the chloride ion concentration (in Cl) in the permeated water with respect to the number of days from the start of the supply of the warm pure water into the ultrafiltration membrane module was measured. The results are shown in table 1. The changes with time in the chloride ion concentrations of example 1 and comparative example are shown in the graph of fig. 6.

TABLE 1

(example 2)

In example 1, the opening degree of the valve V2 was set so that the flow rate discharged as the discharge water from the nozzle 6a was changed within a range of 0% to 10% with respect to the total flow rate discharged from the

nozzles

6a and 6b as shown in table 2, and the permeated water was collected from the nozzle 6 b. After 55 days from the start of passing warm pure water through the ultrafiltration membrane module, the chloride ion concentration (as Cl) in the obtained permeate water was measured. The results are shown in table 2. The relationship between the flow rate of permeated water discharged and the chloride ion concentration in the permeated water in example 2 is shown in the graph of fig. 7.

TABLE 2

(measurement 5 days after the start of Water communication)

Claims

1. An ultrafiltration membrane module characterized by being an ultrafiltration membrane module comprising a plurality of hollow fiber membranes formed of an ultrafiltration membrane and a cylindrical case accommodating the plurality of hollow fiber membranes, wherein,

the cylindrical housing includes, on an outer peripheral surface thereof, a 1 st nozzle and a 2 nd nozzle arranged to be spaced apart from each other in an axial direction of the cylindrical housing, a 3 rd nozzle and a 4 th nozzle arranged at both end portions of the cylindrical housing, and a pair of fixing portions for fixing the plurality of hollow fiber membranes in the axial direction of the cylindrical housing so that open ends of the plurality of hollow fiber membranes face the both end portions of the cylindrical housing, respectively, and sealing the cylindrical housing at respective positions between the one end portion of the cylindrical housing and the 1 st nozzle and between the other end portion of the cylindrical housing and the 2 nd nozzle,

the 1 st nozzle is a treated water inlet pipe for introducing treated water, the 2 nd nozzle is a concentrated water outlet pipe for discharging concentrated water that has not passed through the hollow fiber membranes,

the 3 rd nozzle is a permeate outflow pipe for flowing out permeate having permeated through the hollow fiber membrane, the 4 th nozzle is a discharge outflow pipe for flowing out discharge having permeated through the hollow fiber membrane,

the ratio of the amount of flow out of the permeate outlet pipe to the amount of flow out of the discharged water outlet pipe, i.e., the ratio of the amount of flow out of the permeate outlet pipe to the amount of flow out of the discharged water outlet pipe, is 90/10 to 99/1.

2. An ultrafiltration membrane module according to claim 1, wherein the permeated water outlet pipe is provided closer to the concentrated water outlet pipe than the treated water inlet pipe.

3. The ultrafiltration membrane assembly of claim 1, wherein the fixation portion is formed of an epoxy.

4. A method for producing ultrapure water, characterized in that in an ultrafiltration membrane module comprising a plurality of hollow fiber membranes formed from an ultrafiltration membrane and a cylindrical case for housing the hollow fiber membranes,

the cylindrical case includes, on an outer peripheral surface thereof, a 1 st nozzle and a 2 nd nozzle arranged to be spaced apart from each other in an axial direction of the cylindrical case, a 3 rd nozzle and a 4 th nozzle arranged at both end portions of the cylindrical case, and a pair of fixing portions that fix the plurality of hollow fiber membranes in the axial direction of the cylindrical case so that open ends of the plurality of hollow fiber membranes face the both end portions of the cylindrical case, respectively, and seal the cylindrical case at respective positions between the one end portion of the cylindrical case and the 1 st nozzle and between the other end portion of the cylindrical case and the 2 nd nozzle,

introducing the water to be treated into the ultrafiltration membrane module from the 1 st nozzle, and discharging the concentrated water that has not permeated through the hollow fiber membranes from the 2 nd nozzle,

the 3 rd nozzle of the cylindrical case is used to discharge the permeated water after permeating the hollow fiber membranes, and the 4 th nozzle is used to discharge the discharged water after permeating the hollow fiber membranes,

the ratio of the outflow from the 3 rd nozzle to the outflow from the 4 th nozzle, i.e., the outflow from the 3 rd nozzle/the outflow from the 4 th nozzle, is 90/10 to 99/1,

the permeated water is obtained as ultrapure water.

5. The method for producing ultrapure water according to claim 4, wherein chloride ions (Cl) in the water to be treated are contained in the water ^- ) The concentration is 0.01 mu g/L-2 mu g/L calculated by Cl.

6. The method for producing ultrapure water according to claim 4, wherein chloride ions (Cl) in the water to be treated are contained in the water ^- ) The concentration is 1ng/L or less in terms of Cl.

7. The method for producing ultrapure water according to claim 5 or 6, wherein chloride ions (Cl) in the permeated water of the ultrafiltration membrane module ^- ) The concentration is 5ng/L or less in terms of Cl.