JP5245605B2 - Filtration membrane cleaning method and ultrapure water production filtration membrane - Google Patents
Filtration membrane cleaning method and ultrapure water production filtration membrane Download PDFInfo
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- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 claims description 3
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Description
本発明は、超純水製造に使用される濾過膜を、超純水製造工程での使用に先立って予備的に洗浄する方法と、この方法で洗浄された超純水製造用濾過膜に関する。 The present invention relates to a method of preliminarily washing a filtration membrane used for ultrapure water production prior to use in the ultrapure water production step, and a filtration membrane for producing ultrapure water washed by this method.
超純水の製造は、原水に紫外線照射、逆浸透膜分離、膜脱気、イオン交換、限外濾過膜分離などの処理を施すことによって行われている。図１は、超純水製造装置の一例を示すものであり、原水として一次純水製造装置で処理した一次純水を貯留する原水貯留槽２と、原水に紫外線を照射する紫外線照射器３と、イオン交換法による脱塩処理を行うイオン交換塔４と、限外濾過膜６による膜分離を行う限外濾過膜分離装置５とを備えている。
The production of ultrapure water is performed by subjecting raw water to treatments such as ultraviolet irradiation, reverse osmosis membrane separation, membrane degassing, ion exchange, and ultrafiltration membrane separation. FIG. 1 shows an example of an ultrapure water production apparatus, a raw
この超純水製造装置１で超純水を製造するには、各装置（紫外線照射器３、イオン交換塔４、限外濾過膜分離装置５）を接続して製造装置１を設置した後、原水貯留槽２からの原水を紫外線照射器３に供給し、イオン交換塔４、限外濾過膜分離装置５を経て処理水として超純水を得る。
In order to produce ultrapure water with this ultrapure water production apparatus 1, after each apparatus (
この超純水製造装置１により超純水の製造を開始した際には、各装置（紫外線照射器３、イオン交換塔４、限外濾過膜分離装置５）からの溶出等により、不純物（金属イオンなど）が放出され、処理水（超純水）中に混入することがある。このため、処理水中への不純物混入を防ぐことを目的として、超純水製造装置１の設置後、超純水製造の開始に先立って、洗浄水を紫外線照射器３、イオン交換塔４、限外濾過膜分離装置５を経て再び紫外線照射器３に循環させる循環洗浄が行われている。この洗浄は、通常、洗浄水を交換しつつ複数回行われる。この洗浄によって、各装置からの不純物放出量を低減させ、不純物含有量の少ない処理水を得ることができる。
When the production of ultrapure water is started by this ultrapure water production apparatus 1, impurities (metals) are caused by elution from each apparatus (
しかしながら、このように、超純水製造装置１の設置後の循環洗浄では、処理水の不純物濃度を十分に低くするまでに長時間を要していた。また、大量の洗浄水が必要となるため、コスト面の不利が生じていた。 However, in this way, in the circulation cleaning after the installation of the ultrapure water production apparatus 1, it takes a long time to sufficiently reduce the impurity concentration of the treated water. In addition, since a large amount of washing water is required, there is a cost disadvantage.
このため、超純水製造装置を設置した後、短時間で低不純物濃度の超純水を製造できる技術が要望されていた。 For this reason, after installing an ultrapure water manufacturing apparatus, the technique which can manufacture ultrapure water with a low impurity concentration in a short time has been desired.
その対策として新品の濾過膜を超純水製造装置に設置する前に予備洗浄する方法が考えられている。即ち、新品の濾過膜には、製造工程で使用された接着剤などに由来するＴＯＣ、カルシウム分、重金属などが付着しているので、これを予備洗浄によって予め除去する。 As a countermeasure, a method of pre-cleaning a new filtration membrane before installing it in an ultrapure water production apparatus is considered. That is, since the TOC, calcium content, heavy metal, etc. derived from the adhesive used in the manufacturing process are attached to the new filter membrane, this is removed in advance by preliminary cleaning.
例えば、特許文献１には、限外濾過膜をまず酸洗浄し、次いで超純水で洗浄する予備洗浄方法が提案されている。この予備洗浄によって、限外濾過膜の予備洗浄時間、ひいては超純水製造装置の立ち上げ期間を短縮することができる。 For example, Patent Document 1 proposes a preliminary cleaning method in which an ultrafiltration membrane is first cleaned with an acid and then cleaned with ultrapure water. By this preliminary cleaning, the preliminary cleaning time of the ultrafiltration membrane, and thus the startup period of the ultrapure water production apparatus can be shortened.
また、特許文献２には、製造された膜モジュールを熱水で通水洗浄する方法が提案されている。この特許文献２では、この熱水洗浄後、常温の超純水による通水洗浄が行われている。
Further,
また、特許文献３には、常温の超純水を用い、通水洗浄工程と浸漬洗浄工程とその後の排出工程からなる洗浄サイクルを繰り返し行うことが提案されている。
従来の方法によれば、一応の洗浄効果が得られるが、より一層の洗浄効率の向上で、所定の清浄度を有する濾過膜を得るための予備洗浄に要する時間をより一層短縮する技術が望まれる。 According to the conventional method, a temporary cleaning effect can be obtained, but a technique for further reducing the time required for preliminary cleaning for obtaining a filtration membrane having a predetermined cleanness by further improving the cleaning efficiency is desired. It is.
特に、特許文献１の方法のように、酸洗浄を行う方法では、酸洗浄によって、カルシウム分や重金属類の不純物を除去することはできるものの、その後の超純水洗浄によるＴＯＣやアニオン成分（酸洗浄に伴う塩化物イオンなど）の除去に長時間を要するため、その改良が望まれている。 In particular, in the method of acid cleaning as in the method of Patent Document 1, although calcium content and heavy metal impurities can be removed by acid cleaning, TOC and anion components (acid acid) by subsequent ultrapure water cleaning can be used. Since it takes a long time to remove chloride ions and the like accompanying cleaning, an improvement is desired.
本発明は、従来法よりも更に効率的な洗浄を行うことができ、濾過膜の予備洗浄に要する時間をより一層短縮することができる濾過膜の洗浄方法と、この方法により洗浄された超純水製造用濾過膜を提供することを目的とする。 The present invention is capable of performing more efficient cleaning than the conventional method and can further reduce the time required for preliminary cleaning of the filtration membrane, and the ultrapure cleaned by this method. An object is to provide a filtration membrane for water production.
本発明（請求項１）の濾過膜の洗浄方法は、超純水製造に使用される濾過膜を、超純水製造工程での使用に先立って予備的に洗浄する方法であって、前記濾過膜を７０℃以上の純水で洗浄する高温純水洗浄工程と、該高温純水洗浄工程の後に、該濾過膜を常温の超純水で洗浄する超純水洗浄工程とを有し、前記高温純水洗浄工程における前記純水が、比抵抗；１７ＭΩ・ｃｍ以上、微粒子（１ｍＬ中、０．１μｍ径以上の微粒子数）；５個以下、微生物（１Ｌ中微生物数）；１０個以下、有機物（ＴＯＣ）；１０μｇ／Ｌ以下の純水であり、前記超純水洗浄工程における前記超純水が、比抵抗；１８ＭΩ・ｃｍ以上、微粒子（１ｍＬ中、０．１μｍ径以上の微粒子数）；１個以下、微生物（１Ｌ中微生物数）；１個以下、有機物（ＴＯＣ）；５μｇ／Ｌ以下の超純水であり、前記高温純水洗浄工程が、通水洗浄と浸漬洗浄とを交互に繰り返し実施するものであり、前記超純水洗浄工程における洗浄排水の水質項目が、比抵抗：１８ＭΩ・ｃｍ以上、ＴＯＣ：１０００ｎｇ／Ｌ以下、金属イオン：０．５ｎｇ／Ｌ以下、アニオン：５ｎｇ／Ｌ以下となったときに、前記濾過膜の洗浄を終了することを特徴とする。 The filtration membrane cleaning method of the present invention (Claim 1) is a method of preliminarily cleaning a filtration membrane used for ultrapure water production prior to use in the ultrapure water production process, wherein the filtration membrane has a high temperature pure water washing step of washing the membrane with pure water at least 70 ° C., after the high temperature pure water washing process, and ultrapure water cleaning step of cleaning the the filtration membranes at room temperature in ultra pure water, the The pure water in the high-temperature pure water washing step has a specific resistance of 17 MΩ · cm or more, fine particles (the number of fine particles having a diameter of 0.1 μm or more in 1 mL); 5 or less, microorganisms (the number of microorganisms in 1 L); Organic substance (TOC): pure water of 10 μg / L or less, and the ultrapure water in the ultrapure water washing step has a specific resistance: 18 MΩ · cm or more, fine particles (number of fine particles having a diameter of 0.1 μm or more in 1 mL) 1 or less, microorganism (the number of microorganisms in 1 L); 1 or less, organic substance (TOC); 5 μ / L is less ultrapure water, the hot pure water washing step state, and are not repeatedly carried out and immersion cleaning and passing water washed alternately, the water quality of the washing drainage in the ultrapure water cleaning step, specific resistance: 18 M [Omega · cm or more, TOC: 1000 ng / L or less, metal ions: 0.5 ng / L or less, anion: when it becomes less than 5 ng / L, and features that you finished the cleaning of the filtration membrane To do.
請求項２の濾過膜の洗浄方法は、請求項１において、前記高温純水洗浄工程は、前記濾過膜を備える膜モジュールに純水を一過式で通水する通水洗浄過程と、該通水洗浄過程後、該膜モジュール内に純水を満たした状態で静置する浸漬洗浄過程と、該浸漬洗浄過程後、膜モジュール内の水を排出する排出過程とを含む洗浄サイクルを、複数回繰り返し実施するものであることを特徴とする。 According to a second aspect of the present invention, there is provided a method for cleaning a filtration membrane according to the first aspect, wherein the high-temperature pure water cleaning step includes a water-pass cleaning process in which pure water is passed through a membrane module including the filtration membrane in a transient manner. After the water cleaning process, a cleaning cycle including a dip cleaning process of leaving the membrane module filled with pure water, and a draining process of discharging the water in the membrane module after the dip cleaning process is performed a plurality of times. It is characterized by being repeatedly performed.
請求項３の濾過膜の洗浄方法は、請求項１又は２において、前記高温純水洗浄工程を３日以上行うことを特徴とする。 According to a third aspect of the present invention, there is provided the method for cleaning a filtration membrane according to the first or second aspect, wherein the high-temperature pure water cleaning step is performed for 3 days or more.
請求項４の濾過膜の洗浄方法は、請求項１ないし３のいずれか１項において、前記超純水洗浄工程が、通水洗浄と浸漬洗浄とを交互に繰り返し実施するものであることを特徴とする。 According to a fourth aspect of the present invention, there is provided a method for cleaning a filtration membrane according to any one of the first to third aspects, wherein the ultrapure water cleaning step alternately and repeatedly performs water flow cleaning and immersion cleaning. And
請求項５の濾過膜の洗浄方法は、請求項４において、前記超純水洗浄工程は、前記濾過膜を備える膜モジュールに超純水を一過式で通水する通水洗浄過程と、該通水洗浄過程後、該膜モジュール内に超純水を満たした状態で静置する浸漬洗浄過程と、該浸漬洗浄過程後、膜モジュール内の水を排出する排出過程とを含む洗浄サイクルを、複数回繰り返し実施するものであることを特徴とする。
The filtration membrane cleaning method according to
請求項６の濾過膜の洗浄方法は、請求項１ないし５のいずれか１項において、前記超純水洗浄工程を３日以上行うことを特徴とする。 According to a sixth aspect of the present invention, there is provided a method for cleaning a filtration membrane according to any one of the first to fifth aspects, wherein the ultrapure water cleaning step is performed for 3 days or more.
請求項７の濾過膜の洗浄方法は、請求項１ないし６のいずれか１項において、前記高温純水洗浄工程に先立ち、前記濾過膜を酸剤で洗浄する酸洗浄工程を有することを特徴とする。 The filtration membrane cleaning method according to claim 7 includes an acid cleaning step of cleaning the filtration membrane with an acid agent prior to the high-temperature pure water cleaning step according to any one of claims 1 to 6. To do.
請求項８の濾過膜の洗浄方法は、請求項７において、前記酸洗浄工程で用いる酸剤が、塩酸、硝酸、硫酸、フッ酸、炭酸、過硫酸、過塩酸、過塩素酸、クエン酸、酢酸、シュウ酸、及び酒石酸よりなる群から選ばれる１種又は２種以上であり、該酸剤を０．１重量％以上の濃度の水溶液として用いることを特徴とする。 The filtration membrane cleaning method according to claim 8 is the method according to claim 7, wherein the acid agent used in the acid cleaning step is hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, carbonic acid, persulfuric acid, perhydrochloric acid, perchloric acid, citric acid, One or more selected from the group consisting of acetic acid, oxalic acid, and tartaric acid, wherein the acid agent is used as an aqueous solution having a concentration of 0.1% by weight or more.
本発明（請求項９）の超純水製造用濾過膜は、請求項１ないし８のいずれか１項に記載の濾過膜の洗浄方法によって洗浄されたものであることを特徴とする。 The filtration membrane for producing ultrapure water of the present invention (Claim 9) is characterized by being washed by the filtration membrane washing method according to any one of Claims 1 to 8.
請求項１０の超純水製造用濾過膜は、請求項９において、前記濾過膜が限外濾過膜であることを特徴とする。 A filtration membrane for producing ultrapure water according to claim 10 is characterized in that, in claim 9, the filtration membrane is an ultrafiltration membrane.
本発明によれば、高温の純水を用い、通水洗浄と浸漬洗浄とを交互に行う高温純水洗浄により、濾過膜のＴＯＣや重金属を短期間で除去することができ、超純水製造装置に備え付ける濾過膜の予備洗浄時間、引いては超純水製造装置の立ち上げ期間を短縮することができる。特に、この高温純水洗浄の前に酸洗浄を行うことにより、濾過膜のカルシウム分や重金属を短期間で除去することができるので、より確実に濾過膜の予備洗浄時間を短縮することができる。 According to the present invention, by using high-temperature pure water, TOC and heavy metals in the filtration membrane can be removed in a short period of time by high-temperature pure water cleaning in which water-pass cleaning and immersion cleaning are alternately performed. It is possible to shorten the pre-cleaning time of the filtration membrane provided in the apparatus, and thus the startup period of the ultrapure water production apparatus. In particular, by performing acid cleaning before this high-temperature pure water cleaning, the calcium content and heavy metals in the filtration membrane can be removed in a short period of time, so the pre-cleaning time for the filtration membrane can be shortened more reliably. .
例えば、限外濾過（ＵＦ）膜から溶出するＣａ濃度が１ｎｇ／Ｌ未満、Ｃｌ濃度が１ｎｇ／Ｌ未満とするために必要な洗浄時間は、以下の通りであり、本発明に従って、酸洗浄と高温純水洗浄とその後の超純水洗浄とを実施することにより、予備洗浄に要する時間を従来法よりも大幅に短縮することができる。 For example, the cleaning time required for the Ca concentration eluted from the ultrafiltration (UF) membrane to be less than 1 ng / L and the Cl concentration to be less than 1 ng / L is as follows. By performing the high-temperature pure water cleaning and the subsequent ultrapure water cleaning, the time required for the preliminary cleaning can be significantly reduced as compared with the conventional method.
常温超純水洗浄（常温の純水による通水洗浄）のみ：９０日間
酸洗浄と常温超純水洗浄：６０日間（３０日＋３０日）
酸洗浄と高温純水洗浄と常温超純水洗浄：３０日間（２日＋１４日＋１４日）
Room temperature ultrapure water cleaning (water cleaning with room temperature pure water) only: 90 days Acid cleaning and room temperature ultrapure water cleaning: 60 days (30 days + 30 days)
Acid cleaning, high temperature pure water cleaning and room temperature ultra pure water cleaning: 30 days (2 days + 14 days + 14 days)
以下に本発明の濾過膜の洗浄方法及び超純水製造用濾過膜の実施の形態を詳細に説明する。 Embodiments of a filtration membrane cleaning method and a filtration membrane for producing ultrapure water according to the present invention will be described in detail below.
なお、本発明において、洗浄に用いる純水、超純水とは、次のような水質のものをさす。 In the present invention, pure water and ultrapure water used for cleaning refer to water having the following water quality.
＜純水＞
・比抵抗；１７ＭΩ・ｃｍ以上
・微粒子（１ｍＬ中、０．１μｍ径以上の微粒子数）；５個以下
・微生物（１Ｌ中微生物数）；１０個以下
・有機物（ＴＯＣ）；１０μｇ／Ｌ以下
<Pure water>
Specific resistance: 17 MΩ · cm or more Fine particles (number of fine particles having a diameter of 0.1 μm or more in 1 mL): 5 or less Microorganisms (number of microorganisms in 1 L): 10 or less Organic matter (TOC): 10 μg / L or less
＜超純水＞
・比抵抗；１８ＭΩ・ｃｍ以上
・微粒子（１ｍＬ中、０．１μｍ径以上の微粒子数）；１個以下
・微生物（１Ｌ中微生物数）；１個以下
・有機物（ＴＯＣ）；５μｇ／Ｌ以下
<Ultra pure water>
Specific resistance: 18 MΩ · cm or more Fine particles (number of fine particles having a diameter of 0.1 μm or more in 1 mL): 1 or less Microorganisms (number of microorganisms in 1 L): 1 or less Organic matter (TOC): 5 μg / L or less
［濾過膜］
本発明で洗浄対象とする濾過膜は、超純水製造に使用される濾過膜、即ち、超純水製造装置に設置する前の濾過膜であり、通常は限外濾過（ＵＦ）膜が用いられるが、その他、精密濾過（ＭＦ）膜、ナノ濾過（ＮＦ）膜などが適用される場合もある。
[Filtration membrane]
The filtration membrane to be cleaned in the present invention is a filtration membrane used for ultrapure water production, that is, a filtration membrane before being installed in an ultrapure water production apparatus, and usually an ultrafiltration (UF) membrane is used. In addition, a microfiltration (MF) membrane, a nanofiltration (NF) membrane, or the like may be applied.
濾過膜の膜材質としては、本発明における高温純水洗浄工程で用いる高温の純水に耐え得る耐熱性を有することが必要であり、また、高温純水洗浄工程に先立ち酸洗浄を行う場合は、耐熱性に加えて更にこの酸洗浄で用いる酸剤に対する耐酸性にも優れることが望まれる。 As the membrane material of the filtration membrane, it is necessary to have heat resistance that can withstand the high-temperature pure water used in the high-temperature pure water cleaning step in the present invention, and when performing acid cleaning prior to the high-temperature pure water cleaning step In addition to heat resistance, it is also desired to be excellent in acid resistance against the acid agent used in this acid cleaning.
ＵＦ膜等の濾過膜の膜材料としては、特に制限はないが、ポリスルフォン系、ポリオレフィン系、ポリビニルアルコール系、セルロース系等の材料が挙げられ、特に、ポリスルフォン系の材料が好ましい。 A membrane material for a filtration membrane such as a UF membrane is not particularly limited, and examples thereof include polysulfone-based, polyolefin-based, polyvinyl alcohol-based, and cellulose-based materials, and polysulfone-based materials are particularly preferable.
また、濾過膜モジュールの形状としても特に制限はなく、中空糸状、管状、プリーツ状、スパイラル状、プレートアンドフレーム状等、各種のものを適用することができる。 Moreover, there is no restriction | limiting in particular also as a shape of a filtration membrane module, Various things, such as a hollow fiber shape, a tubular shape, a pleat shape, a spiral shape, a plate and frame shape, are applicable.
［高温純水洗浄工程］
本発明において、濾過膜をまず７０℃以上の純水で洗浄する高温純水洗浄を行う。
[High-temperature pure water cleaning process]
In the present invention, the filtration membrane is first washed with pure water at 70 ° C. or higher.
この高温純水洗浄に用いる純水の温度が７０℃未満では、十分な洗浄効果を得ることができない。ただし、純水の温度が濾過膜の耐熱性の上限を超えると、濾過膜が熱収縮を起こすため、この純水の温度は、濾過膜の耐熱性の上限温度以下とする。また、温度が高過ぎ、純水が水蒸気となってしまうような高温では十分な洗浄効果が得られないため、用いる純水の温度は７０℃以上で純水が液体を維持する温度以下、好ましくは８０〜８５℃とすることが望ましい。 If the temperature of pure water used for this high temperature pure water cleaning is less than 70 ° C., a sufficient cleaning effect cannot be obtained. However, when the temperature of the pure water exceeds the upper limit of the heat resistance of the filtration membrane, the filtration membrane causes thermal shrinkage. Therefore, the temperature of the pure water is set to be equal to or lower than the upper limit temperature of the heat resistance of the filtration membrane. Moreover, since the temperature is too high and a sufficient cleaning effect cannot be obtained at a high temperature at which pure water becomes water vapor, the temperature of pure water to be used is 70 ° C. or higher, preferably below the temperature at which pure water maintains a liquid. Is preferably 80 to 85 ° C.
この高温純水は、純水又は超純水を電気ヒータ又は温熱蒸気との熱交換などにより加熱して調製される。 This high-temperature pure water is prepared by heating pure water or ultrapure water by heat exchange with an electric heater or hot steam.
温純水製造用に高温で限外濾過膜を使用する際は、使用の前処理としての通水を兼ねることができるためより好ましい。 When using an ultrafiltration membrane at a high temperature for producing warm pure water, it is more preferable because it can also serve as water pretreatment for use.
本発明において、高温純水洗浄工程は、通水洗浄と浸漬洗浄とを交互に繰り返し行うものであるが、好ましくは、濾過膜を備える膜モジュールに高温の純水を一過式で通水する通水洗浄過程と、該通水洗浄過程後、該膜モジュール内に純水を満たした状態で静置する浸漬洗浄過程と、該浸漬過洗浄程後、膜モジュール内の水を排出する排出過程とを含む洗浄サイクルを、複数回繰り返し実施する。 In the present invention, the high-temperature pure water cleaning step is one in which water-pass cleaning and immersion cleaning are alternately repeated. Preferably, high-temperature pure water is passed through a membrane module including a filtration membrane in a transient manner. A water-washing process, an immersion-cleaning process in which the membrane module is left in a state of being filled with pure water after the water-washing process, and a discharge process in which the water in the membrane module is discharged after the immersion over-cleaning process The washing cycle including the above is repeated a plurality of times.
以下、各洗浄過程について説明する。 Hereinafter, each cleaning process will be described.
＜通水洗浄過程＞
通水洗浄過程では、膜モジュールに７０℃以上の高温の純水を一過式で通水し、膜を透過した透過水を系外へ排出する。
<Water washing process>
In the water flow cleaning process, high-temperature pure water of 70 ° C. or higher is passed through the membrane module in a transient manner, and the permeated water that has passed through the membrane is discharged out of the system.
この通水洗浄において、通水する純水の流速が小さ過ぎると十分な洗浄効果が得られず、大き過ぎると膜に対する負荷が大きくなる。従って、通水洗浄時の流速は、膜の規定流量３〜１５ｍ３／ｈに対して１０〜１０００Ｌ／ｈ、即ち、膜の規定流量をＡ（ｍ３／ｈ）、通水洗浄時の流量をＢ（Ｌ／ｈ）とした場合、Ｂ（Ｌ／ｈ）／Ａ（ｍ３／ｈ）が３０〜７０程度となるようにすることが好ましい。 In this water flow cleaning, if the flow rate of pure water flowing through is too small, a sufficient cleaning effect cannot be obtained, and if it is too large, the load on the membrane increases. Therefore, the flow rate at the time of washing with water is 10 to 1000 L / h with respect to the specified flow rate of 3 to 15 m 3 / h of the membrane, that is, the specified flow rate of the membrane is A (m 3 / h), Is B (L / h), B (L / h) / A (m 3 / h) is preferably about 30 to 70.
＜浸漬洗浄過程＞
上記の通水洗浄後は、純水の通水を停止し、膜モジュール内に純水を満たした状態で静置する浸漬洗浄を行う。この場合、加温手段等を設けて膜モジュール内の純水温度を一定範囲に維持しても良く、このような温度制御を行わず、放熱により膜モジュール内の純水の温度が経時により低下するものであっても良い。
<Immersion cleaning process>
After the above-mentioned water cleaning, the pure water is stopped from flowing, and immersion cleaning is performed by leaving the membrane module filled with pure water. In this case, the temperature of the pure water in the membrane module may be maintained within a certain range by providing a heating means or the like. Without such temperature control, the temperature of the pure water in the membrane module decreases with time due to heat dissipation. It may be what you do.
＜排出過程＞
上記の浸漬洗浄後は、膜モジュール内の水を排出する。水の排出は、通水洗浄時と同じ方向に押出用の気体を送入して行うことが好ましい。この水の押出に用いる気体は、不純物の少ない高純度の窒素又は空気であることが好ましく、例えば、純度９９．９９９容量％以上の窒素又はＨＥＰＡ（Ｈｉｇｈ Ｅｆｆｉｃｉｅｎｃｙ Ｐａｒｔｉｃｕｌａｔｅ Ａｉｒ）フィルター以上のフィルターで濾過した空気であることが好ましい。純度９９．９９９容量％以上の窒素又はＨＥＰＡフィルター以上のフィルターで濾過した空気を送入することにより、膜モジュールの汚染や微粒子の混入を防ぐことができる。ここで、ＨＥＰＡフィルターは、定格風量において、圧力損失が２５ｍｍＨ２Ｏ以下で０．３μｍ粒子を９９．９７％以上で捕集するフィルターである。ＨＥＰＡフィルターを超えるフィルターとしては、例えば、定格風量において、圧力損失が２５ｍｍＨ２Ｏ以下で０．１μｍ粒子を９９．９９９５％以上で捕集するＵＬＰＡ（Ｕｌｔｒａ Ｌｏｗ Ｐｅｎｅｔｒａｔｉｏｎ Ａｉｒ）フィルターなどを挙げることができる。
<Discharge process>
After the above immersion cleaning, the water in the membrane module is discharged. It is preferable that the water is discharged by feeding an extrusion gas in the same direction as in the water washing. The gas used for the extrusion of water is preferably high-purity nitrogen or air with few impurities. For example, the gas is filtered through a filter having a purity of 99.999% or more by nitrogen or a HEPA (High Efficiency Particulate Air) filter or more. Air is preferred. Contamination of the membrane module and mixing of fine particles can be prevented by sending air filtered through a filter having a purity of 99.999% or more by nitrogen or a HEPA filter or more. Here, the HEPA filter is a filter that collects 0.3 μm particles at 99.97% or more with a pressure loss of 25 mmH 2 O or less at the rated air volume. Examples of the filter that exceeds the HEPA filter include an ULPA (Ultra Low Penetration Air) filter that collects 0.1 μm particles at 99.9995% or more at a rated air volume and a pressure loss of 25 mmH 2 O or less. .
膜モジュールに送入する気体の圧力は、５〜２０ｋＰａであることが好ましく、８〜１５ｋＰａであることがより好ましい。送入する気体の圧力が５ｋＰａ未満であると、水の排出に長時間を要するおそれがある。送入する気体の圧力が２０ｋＰａを超えると、膜が損傷を受けるおそれがある。 The pressure of the gas fed into the membrane module is preferably 5 to 20 kPa, and more preferably 8 to 15 kPa. If the pressure of the gas to be fed is less than 5 kPa, it may take a long time to discharge water. If the pressure of the gas to be fed exceeds 20 kPa, the membrane may be damaged.
＜洗浄サイクル＞
高温純水洗浄工程における、上記通水洗浄過程、浸漬洗浄過程及び排出過程を一サイクルとする洗浄サイクルに要する時間は、例えば、以下の範囲とすることが好ましく、本発明においては、このような洗浄サイクルを３〜２０回、例えば３日以上４週間以内行うことが好ましい。
<Washing cycle>
In the high-temperature pure water cleaning step, the time required for the cleaning cycle in which the water-passing cleaning process, the immersion cleaning process, and the discharge process are one cycle is preferably, for example, in the following range. The washing cycle is preferably performed 3 to 20 times, for example, 3 days or more and 4 weeks or less.
通水洗浄過程：５〜８時間
浸漬洗浄過程：１０〜１８時間
排出過程（気体送入後の放置時間）：１０〜３０分
Water cleaning process: 5 to 8 hours Immersion cleaning process: 10 to 18 hours Discharge process (standing time after gas feed): 10 to 30 minutes
通水洗浄過程及び浸漬洗浄過程の洗浄時間が上記範囲よりも短いと十分な洗浄効果を得ることができず、長いと使用純水量が徒に多くなると共に、洗浄工程に長時間を要し、好ましくない。また、排出過程において、気体送入後、直ちに次の通水洗浄に移行することなく、上述のように１０〜３０分放置した後、次の工程に移行すると、系内の水を十分に排出することができ、洗浄効率を高めることができる。なお、気体送入による排出は１分程度である。 If the cleaning time of the water flow cleaning process and the immersion cleaning process is shorter than the above range, it is not possible to obtain a sufficient cleaning effect, and if it is long, the amount of pure water used increases and the cleaning process takes a long time, It is not preferable. Also, in the discharge process, the gas in the system is not immediately transferred to the next water washing, but left for 10 to 30 minutes as described above. Cleaning efficiency can be increased. In addition, the discharge | emission by gas feeding is about 1 minute.
なお、本発明においては、特に、日中の作業時間において、通水洗浄過程を行い、その後夜間において、通水を停止して膜モジュール内に高温純水を満たした状態で浸漬洗浄を行い、翌日の作業開始時に膜モジュール内の水を排出し、その後次の洗浄サイクルに移行するようにすることが、作業効率の面で好ましい。 In the present invention, in particular, during the daytime working time, the water flow cleaning process is performed, and at night, the water flow is stopped and the membrane module is immersed and washed with high temperature pure water. It is preferable from the viewpoint of work efficiency that the water in the membrane module is discharged at the start of work on the next day, and then transferred to the next cleaning cycle.
この場合、浸漬洗浄過程において、洗浄する膜モジュールの仕様によっても異なるが、温度制御を行わないと、浸漬洗浄開始初期に７０〜８５℃であった膜モジュール内の純水は、浸漬洗浄開始後２時間程度で７０℃未満となるが、７０℃以上の純水に浸漬された状態が１時間以上あれば、十分な洗浄効果を得ることができる。 In this case, in the immersion cleaning process, although it depends on the specification of the membrane module to be cleaned, if temperature control is not performed, the pure water in the membrane module that was 70 to 85 ° C. at the beginning of the immersion cleaning is Although it becomes less than 70 degreeC in about 2 hours, if the state immersed in the pure water of 70 degreeC or more is 1 hour or more, sufficient cleaning effect can be acquired.
＜洗浄の終了判定＞
高温純水洗浄工程の洗浄の終了判定は、洗浄時に膜モジュールから排出される洗浄排水（膜の透過水）のＴＯＣを測定し、ＴＯＣ濃度が所定の濃度以下、例えば５μｇ／Ｌ以下となったことを確認することにより行うことができる。
<Washing end determination>
The end of cleaning in the high-temperature pure water cleaning process was determined by measuring the TOC of the cleaning wastewater (membrane permeated water) discharged from the membrane module during cleaning, and the TOC concentration became a predetermined concentration or less, for example, 5 μg / L or less. This can be done by confirming this.
［超純水洗浄工程］
上記高温純水洗浄工程後は、濾過膜を超純水で洗浄する超純水洗浄を行う。この超純水洗浄に用いる超純水の温度は常温、例えば、２０〜２６℃程度で良い。
[Ultrapure water cleaning process]
After the high temperature pure water cleaning step, ultra pure water cleaning is performed to clean the filtration membrane with ultra pure water. The temperature of the ultrapure water used for this ultrapure water cleaning may be room temperature, for example, about 20 to 26 ° C.
即ち、７０℃以上の高温の純水で洗浄する高温純水洗浄工程によれば、高い洗浄効果が得られるが、このような高温の超純水を得ることは困難であることから、高温純水洗浄後は、より純度の高い超純水を用いた超純水洗浄を行う。 That is, according to the high-temperature pure water cleaning step of cleaning with high-temperature pure water of 70 ° C. or higher, a high cleaning effect is obtained, but it is difficult to obtain such high-temperature ultrapure water. After the water cleaning, ultra pure water cleaning using higher purity ultra pure water is performed.
本発明において、超純水洗浄工程も、高温純水洗浄工程と同様、通水洗浄と浸漬洗浄とを交互に繰り返し行うことが好ましく、特に、濾過膜を備える膜モジュールに超純水を一過式で通水する通水洗浄過程と、該通水洗浄過程後、該膜モジュール内に超純水を満たした状態で静置する浸漬洗浄過程と、該浸漬洗浄過程後、膜モジュール内の水を排出する排出過程とを含む洗浄サイクルを、複数回繰り返し実施することが好ましい。 In the present invention, the ultrapure water cleaning step is preferably performed alternately and repeatedly with water-passage cleaning and immersion cleaning as in the high-temperature pure water cleaning step, and in particular, ultrapure water is passed through a membrane module including a filtration membrane. A water-washing process in which water is passed by the formula, a water-washing process in which the membrane module is allowed to stand in a state filled with ultrapure water after the water-washing process, and a water in the membrane module after the water-washing process. It is preferable to repeatedly perform a cleaning cycle including a discharging process of discharging water.
以下、各洗浄過程について説明する。 Hereinafter, each cleaning process will be described.
＜通水洗浄過程＞
通水洗浄過程では、膜モジュールに超純水を一過式で通水し、膜を透過した透過水を系外へ排出する。
<Water washing process>
In the water flow cleaning process, ultrapure water is passed through the membrane module in a transient manner, and the permeated water that has passed through the membrane is discharged out of the system.
この通水洗浄において、通水する超純水の流速が小さ過ぎると十分な洗浄効果が得られず、大き過ぎると膜に対する負荷が大きくなる。従って、通水洗浄時の流速は、膜の規定流量３〜１５ｍ３／ｈに対して１００００Ｌ／ｈ、即ち、膜の規定流量をＡ（ｍ３／ｈ）、通水洗浄時の流量をＢ（Ｌ／ｈ）とした場合、Ｂ（Ｌ／ｈ）／Ａ（ｍ３／ｈ）が６６６〜３３３３程度となるようにすることが好ましい。 In this water flow cleaning, if the flow rate of the ultrapure water flowing through is too small, a sufficient cleaning effect cannot be obtained, and if it is too large, the load on the membrane increases. Therefore, the flow rate at the time of water flow cleaning is 10,000 L / h with respect to the specified flow rate of the membrane of 3 to 15 m 3 / h, that is, the specified flow rate of the membrane is A (m 3 / h), and the flow rate at the time of water flow cleaning is B In the case of (L / h), it is preferable that B (L / h) / A (m 3 / h) be about 666-3333.
＜浸漬洗浄過程＞
上記の通水洗浄後は、超純水の通水を停止し、膜モジュール内に超純水を満たした状態で静置する浸漬洗浄を行う。
<Immersion cleaning process>
After the water flow cleaning described above, the water flow of ultrapure water is stopped, and immersion cleaning is performed in which the membrane module is left standing in a state where the ultrapure water is filled.
＜排出過程＞
上記の浸漬洗浄後は、膜モジュール内の水を排出する。水の排出は、通水洗浄時と同じ方向に押出用の気体を送入して行うことが好ましい。この水の押出に用いる気体は、前述の高温純水洗浄工程における排出過程で用いる気体と同様、不純物の少ない高純度の窒素又は空気であることが好ましく、送入する気体の圧力についても、前述の高温純水洗浄工程における排出過程と同様の条件を採用することができる。
<Discharge process>
After the above immersion cleaning, the water in the membrane module is discharged. It is preferable that the water is discharged by feeding an extrusion gas in the same direction as in the water washing. The gas used for the water extrusion is preferably high-purity nitrogen or air with few impurities, similar to the gas used in the discharge process in the high-temperature pure water washing step, and the pressure of the gas to be fed is also described above. The same conditions as in the discharging process in the high temperature pure water cleaning step can be adopted.
＜洗浄サイクル＞
超純水洗浄工程における、上記通水洗浄過程、浸漬洗浄過程及び排出過程を一サイクルとする洗浄サイクルに要する時間は、例えば、以下の範囲とすることが好ましく、本発明においては、このような洗浄サイクルを２０〜６０回、例えば３日以上１週間以内行うことが好ましい。
<Washing cycle>
In the ultrapure water cleaning process, the time required for the cleaning cycle in which the water cleaning process, the immersion cleaning process, and the discharge process are one cycle is preferably, for example, in the following range. It is preferable to perform the washing cycle 20 to 60 times, for example, 3 days or more and 1 week or less.
通水洗浄過程：０．１〜０．５時間
浸漬洗浄過程：２．０〜２．５時間
排出過程（気体送入後の放置時間）：１０〜３０分
Water cleaning process: 0.1 to 0.5 hours Immersion cleaning process: 2.0 to 2.5 hours Discharge process (standing time after gas feed): 10 to 30 minutes
通水洗浄過程及び浸漬洗浄過程の洗浄時間が上記範囲よりも短いと十分な洗浄効果を得ることができず、長いと使用超純水量が徒に多くなると共に、洗浄工程に長時間を要し、好ましくない。また、排出過程において、気体送入後、直ちに次の通水洗浄に移行することなく、上述のように１０〜３０分放置した後、次の工程に移行すると、系内の水を分に排出することができ、洗浄効率を高めることができる。なお、気体送入による排出は１分程度である。 If the cleaning time of the water flow cleaning process and the immersion cleaning process is shorter than the above range, a sufficient cleaning effect cannot be obtained, and if the cleaning time is longer, the amount of ultrapure water used increases and the cleaning process takes a long time. It is not preferable. Also, in the discharge process, the gas in the system is not immediately transferred to the next water washing, but left for 10 to 30 minutes as described above. Cleaning efficiency can be increased. In addition, the discharge | emission by gas feeding is about 1 minute.
なお、本発明においては、この超純水洗浄工程においても、高温純水洗浄工程と同様に、日中の作業時間において、通水洗浄過程を行い、その後夜間において膜モジュール内に超純水を満たした状態で浸漬洗浄を行い、翌日の作業開始時に膜モジュール内の水を排出し、その後次の洗浄サイクルに移行するようにすることが、作業効率の面で好ましい。 In the present invention, in this ultrapure water cleaning process, as in the high temperature pure water cleaning process, a water cleaning process is performed during the daytime working hours, and then ultrapure water is poured into the membrane module at night. It is preferable from the viewpoint of work efficiency that immersion cleaning is performed in a filled state, water in the membrane module is discharged at the start of work on the next day, and then the process proceeds to the next cleaning cycle.
＜洗浄の終了判定＞
超純水洗浄工程の洗浄の終了判定は、洗浄時に膜モジュールから排出される洗浄排水（膜の透過水）の比抵抗、ＴＯＣ、金属イオン濃度、アニオン濃度などを測定し、これらの水質項目が、例えば、以下の通りとなったことを確認することにより、行うことができる。
<Judgment of end of washing>
The determination of the end of cleaning in the ultrapure water cleaning process is performed by measuring the specific resistance, TOC, metal ion concentration, anion concentration, etc. of the cleaning wastewater (membrane permeated water) discharged from the membrane module during cleaning. For example, it can be performed by confirming that it is as follows.
比抵抗：１８ＭΩ・ｃｍ以上
ＴＯＣ：１０００ｎｇ／Ｌ以下
金属イオン：０．５ｎｇ／Ｌ以下
アニオン：５ｎｇ／Ｌ以下
Specific resistance: 18 MΩ · cm or more TOC: 1000 ng / L or less Metal ion: 0.5 ng / L or less Anion: 5 ng / L or less
［酸洗浄工程］
本発明においては、前述の高温純水洗浄工程に先立ち、濾過膜を酸剤で洗浄する酸洗浄を行っても良く、酸洗浄を行うことにより、濾過膜に付着している重金属類やカルシウム分を効率的に洗浄除去することができる。
[Acid cleaning process]
In the present invention, prior to the above-described high-temperature pure water cleaning step, acid cleaning for cleaning the filtration membrane with an acid agent may be performed. By performing acid cleaning, heavy metals and calcium components adhering to the filtration membrane may be removed. Can be efficiently washed away.
この酸洗浄を行った場合、その後の高温純水洗浄工程により、塩化物イオン等の残留酸成分を効率的に洗浄除去することができる。 When this acid cleaning is performed, residual acid components such as chloride ions can be efficiently cleaned and removed by the subsequent high-temperature pure water cleaning step.
酸洗浄は、酸剤の水溶液を膜モジュールに通水し、膜を透過した透過水を循環させて通水する循環洗浄方式で行うのが好ましい。 The acid cleaning is preferably performed by a circulating cleaning method in which an aqueous solution of an acid agent is passed through the membrane module and the permeated water that has permeated through the membrane is circulated.
この工程で用いる酸剤としては、塩酸、硝酸、硫酸、フッ酸、炭酸、過硫酸、過塩酸、過塩素酸、クエン酸、酢酸、シュウ酸、酒石酸等が挙げられ、なかでも特に、洗浄効果の点から塩酸、硝酸、硫酸、クエン酸が好ましい。これらの酸剤は１種を単独で用いても良く、２種以上を併用しても良い。 Examples of the acid agent used in this step include hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, carbonic acid, persulfuric acid, perhydrochloric acid, perchloric acid, citric acid, acetic acid, oxalic acid, and tartaric acid. From the point of view, hydrochloric acid, nitric acid, sulfuric acid and citric acid are preferable. These acid agents may be used alone or in combination of two or more.
これらの酸剤は、純水に溶解させて、酸濃度が０．１重量％以上、特に０．１〜１０重量％の水溶液として用いるのが好ましい。この酸濃度が上記範囲未満であると、洗浄効果が不十分となりやすくなる。また、この酸濃度が上記範囲を超えると、洗浄操作が難しくなり、かつ薬剤コストが嵩むようになるため好ましくない。また、酸剤の水溶液のｐＨは、６以下、好ましくは５以下、さらに好ましくは４以下とするのが好適である。このｐＨがこの範囲より高いと、洗浄効果が不十分となりやすくなるため好ましくない。 These acid agents are preferably dissolved in pure water and used as an aqueous solution having an acid concentration of 0.1% by weight or more, particularly 0.1 to 10% by weight. If the acid concentration is less than the above range, the cleaning effect tends to be insufficient. On the other hand, if the acid concentration exceeds the above range, the washing operation becomes difficult and the drug cost increases, which is not preferable. The pH of the aqueous acid agent solution is 6 or less, preferably 5 or less, more preferably 4 or less. If the pH is higher than this range, the cleaning effect tends to be insufficient, such being undesirable.
酸洗浄工程の時間は、１〜２日程度、例えば２日程度行うのが好ましい。 The acid washing step is preferably performed for about 1-2 days, for example, about 2 days.
この酸洗浄工程も、膜モジュールに所定時間酸水溶液を循環通水する通水過程と、その後、循環を停止して膜モジュール内に酸水溶液を満たしたまま静置する浸漬洗浄とを交互に繰り返し行うことが好ましい。この場合、循環通水洗浄過程を１〜４時間、浸漬洗浄過程を１２〜１５時間を１サイクルとして、計１サイクル、全洗浄時間が１〜２日程度となるように行うのが好ましい。 This acid cleaning process also repeats alternately a water flow process in which the acid aqueous solution is circulated through the membrane module for a predetermined time and an immersion cleaning in which the circulation is stopped and the membrane module is left standing with the acid aqueous solution filled. Preferably it is done. In this case, it is preferable to perform the circulating water cleaning process for 1 to 4 hours and the immersion cleaning process for 12 to 15 hours as one cycle so that the total cleaning time is about 1 to 2 days.
この酸洗浄工程においても日中の作業時間において、循環通水洗浄過程を行い、その後夜間において膜モジュール内に酸水溶液を満たした状態で浸漬洗浄を行い、翌日の作業開始時に再び次の洗浄サイクルの循環通水洗浄過程に移行するようにすることが、作業効率の面で好ましい。 Also in this acid cleaning process, the circulating water cleaning process is performed during the daytime working hours, and then the immersion cleaning is performed with the acid solution filled in the membrane module at night, and the next cleaning cycle is performed again at the start of the next day's work. It is preferable in terms of work efficiency to shift to the circulating water washing process.
この酸洗浄の洗浄終了判定は特に行う必要はなく、所定の時間の酸洗浄を行った後は、前述の高温純水洗浄工程における排出過程と同様にして系内の酸水溶液を排出し、次の高温純水洗浄工程に移行する。 It is not necessary to determine whether or not the acid cleaning is finished. After the acid cleaning for a predetermined time, the acid aqueous solution in the system is discharged in the same manner as the discharging process in the high-temperature pure water cleaning step described above. Shift to the high temperature pure water cleaning process.
［洗浄期間］
本発明においては、例えば、上記の高温純水洗浄工程と超純水洗浄工程を行う場合、
高温純水洗浄工程：１４〜３０日、例えば２０日
超純水洗浄工程：５〜１４日、例えば７日
合計：２０〜４０日、例えば２７日
という短期間で、また、酸洗浄工程と高温純水洗浄工程と超純水洗浄工程とを行う場合には、
酸洗浄工程：１〜２日、例えば２日
高温純水洗浄工程：１０〜２０日、例えば１４日
超純水洗浄工程：５〜２０日、例えば１４日
合計：２０〜４０日、例えば３０日
という短期間で、濾過膜を、溶出Ｃａ濃度１ｎｇ／Ｌ未満、溶出Ｃｌ濃度１ｎｇ／Ｌ未満の著しく高清浄度に洗浄することができる。
[Washing period]
In the present invention, for example, when performing the above-described high-temperature pure water cleaning step and ultrapure water cleaning step,
High temperature pure water cleaning step: 14-30 days, for example 20 days Ultra pure water cleaning step: 5-14 days, for example 7 days Total: 20-40 days, for example, 27 days, in a short period of time, acid cleaning step and high temperature When performing the pure water cleaning process and the ultrapure water cleaning process,
Acid cleaning step: 1-2 days, for example 2 days High temperature pure water cleaning step: 10-20 days, for example 14 days Ultrapure water cleaning step: 5-20 days, for example 14 days Total: 20-40 days, for example 30 days In a short period of time, the filtration membrane can be washed with a remarkably high cleanliness with an eluted Ca concentration of less than 1 ng / L and an eluted Cl concentration of less than 1 ng / L.
以下に実施例及び比較例を挙げて本発明をより具体的に説明する。 Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
なお、以下において、洗浄に供した膜モジュールは、膜面積３０ｍ3、規定流量１０ｍ3／ｈのポリスルフォン製の未使用の外圧型中空糸膜モジュールである。 In the following description, the membrane module used for cleaning is an unused external pressure hollow fiber membrane module made of polysulfone having a membrane area of 30 m 3 and a specified flow rate of 10 m 3 / h.
また、洗浄に用いた純水及び超純水の水質は以下の通りであり、モジュール内の水の排出には、ＨＡＰＡフィルターで濾過した圧力１０ｋＰａの空気を用いた。 Moreover, the quality of the pure water and the ultrapure water used for washing | cleaning are as follows, The air of the pressure of 10 kPa filtered with the HAPA filter was used for discharge | emission of the water in a module.
＜純水＞
・比抵抗；１７．５ＭΩ・ｃｍ
・微粒子（１ｍＬ中、０．１μｍ径以上の微粒子数）；２個
・微生物（１Ｌ中微生物数）；１個
・有機物（ＴＯＣ）；１０μｇ／Ｌ
<Pure water>
Specific resistance: 17.5 MΩ · cm
・ Microparticles (number of microparticles with a diameter of 0.1 μm or more in 1 mL); 2 microorganisms (number of microorganisms in 1 L); 1 organic substance (TOC); 10 μg / L
＜超純水＞
・比抵抗；１８．２ＭΩ・ｃｍ
・微粒子（１ｍＬ中、０．１μｍ径以上の微粒子数）；０．５個
・微生物（１Ｌ中微生物数）；０．５個
・有機物（ＴＯＣ）；１．５μｇ／Ｌ
<Ultra pure water>
Specific resistance: 18.2 MΩ · cm
・ Microparticles (the number of microparticles having a diameter of 0.1 μm or more in 1 mL); 0.5 ・ Microorganisms (the number of microorganisms in 1 L); 0.5
また、以下の実施例及び比較例において、ＴＯＣの溶出濃度、Ｃｌ−の残留濃度、Ｃａ２＋の溶出濃度は、膜モジュールの透過水についてそれぞれ分析することにより求めた。 In the following Examples and Comparative Examples, the TOC elution concentration, Cl − residual concentration, and Ca 2+ elution concentration were determined by analyzing the permeated water of the membrane module.
［実施例１］
ＵＦ膜モジュールを、以下の高温純水洗浄工程とその後の超純水製造工程で洗浄した。
[Example 1]
The UF membrane module was cleaned in the following high-temperature pure water cleaning step and the subsequent ultrapure water production step.
＜高温純水洗浄工程＞
８０℃の純水を１０００Ｌ／ｈの流量で一過式で通水する通水洗浄過程８時間と、その後静置する浸漬洗浄過程１６時間と、モジュール内の水をブローして排出する排出過程（ブロー後の待機時間）１０分とを１サイクルとし、５サイクル、計５日間行った。なお、浸漬洗浄過程においては特に温度制御は行わなかった。その結果、浸漬洗浄過程の開始時のモジュール内の水の温度は８０℃であったが、浸漬洗浄開始後２時間後には７０℃より低くなり、浸漬洗浄終了時は２３℃であった。
<High temperature pure water cleaning process>
8 hours of water washing process for passing 80 ° C pure water at a flow rate of 1000 L / h in a transient manner, 16 hours of immersion washing process for standing after that, and a discharging process for blowing and discharging water in the module (Standby time after blow) 10 minutes was one cycle, and 5 cycles were performed for a total of 5 days. In the immersion cleaning process, temperature control was not particularly performed. As a result, the temperature of the water in the module at the start of the immersion cleaning process was 80 ° C., but it was lower than 70 ° C. 2 hours after the start of the immersion cleaning, and 23 ° C. at the end of the immersion cleaning.
＜超純水洗浄工程＞
常温（２３℃）の超純水を１００００Ｌ／ｈの流量で一過式で通水する通水洗浄過程０．１時間と、その後静置する浸漬洗浄過程２．０時間と、モジュール内の水をブローして排出する排出過程（ブロー後の待機時間）１０分とを１サイクルとし、５６サイクル、計７日間行った。
<Ultrapure water cleaning process>
Water cleaning process in which ultrapure water at room temperature (23 ° C.) is passed at a flow rate of 10,000 L / h in a transient manner for 0.1 hour, immersion cleaning process in which it is allowed to stand after that for 2.0 hours, and water in the module The discharge process (blow-up time after blow) of 10 minutes was taken as one cycle, and 56 cycles were performed for a total of 7 days.
この常温超純水洗浄開始時のＴＯＣ溶出濃度と、常温超純水洗浄開始から７日後のＴＯＣ溶出濃度を調べ、結果を表１に示した。 The TOC elution concentration at the start of the room temperature ultrapure water cleaning and the TOC elution concentration 7 days after the start of the room temperature ultrapure water cleaning were examined, and the results are shown in Table 1.
［比較例１］
実施例１において、高温純水洗浄工程を行わず、超純水洗浄工程のみを２４０サイクル、１ヶ月間行ったこと以外は同様にして洗浄を行った。
[Comparative Example 1]
In Example 1, the high-temperature pure water cleaning step was not performed, and the cleaning was performed in the same manner except that only the ultrapure water cleaning step was performed for 240 cycles for one month.
このときの常温超純水洗浄開始時のＴＯＣ溶出濃度と、常温超純水洗浄開始から１ヶ月後のＴＯＣ溶出濃度を調べ、結果を表１に示した。 The TOC elution concentration at the start of normal temperature ultrapure water cleaning and the TOC elution concentration one month after the start of normal temperature ultrapure water cleaning were examined, and the results are shown in Table 1.
以上の結果から、高温純水洗浄工程を行わなかった比較例１では、高温純水洗浄工程を行った実施例１に対して、洗浄時間を相当に長くしないと、ＴＯＣ溶出量が十分に低くなるまでの洗浄効果を上げることができないことが分かる。 From the above results, in Comparative Example 1 in which the high-temperature pure water cleaning step was not performed, the TOC elution amount was sufficiently low unless the cleaning time was significantly increased compared to Example 1 in which the high-temperature pure water cleaning step was performed. It turns out that the cleaning effect until it becomes cannot be improved.
［実施例２］
実施例１において、高温純水洗浄工程に先立ち、塩酸を純水に溶解させて０．５重量％濃度としたｐＨ０．１未満の塩酸水溶液を用いた酸洗浄工程を行ったこと以外は同様にして膜モジュールの洗浄を行い、酸洗浄後のＣｌ−残留濃度の経時変化と、常温超純水洗浄開始時ないし開始後のＣａ２＋溶出濃度を調べ、結果を表２に示した。
[Example 2]
In Example 1, prior to the high-temperature pure water cleaning step, the same procedure was performed except that an acid cleaning step was performed using a hydrochloric acid aqueous solution having a pH of less than 0.1, in which hydrochloric acid was dissolved in pure water to a concentration of 0.5% by weight. The membrane module was cleaned, and the time-dependent change in the Cl − residual concentration after acid cleaning and the Ca 2+ elution concentration at the start or after the start of room temperature ultrapure water cleaning were examined. The results are shown in Table 2.
なお、酸洗浄は、酸水溶液を循環通水する循環通水洗浄を２時間、その後静置する浸漬洗浄１５時間を１サイクルとし、１サイクル、１日行った。 The acid cleaning was performed for one cycle for one day, with one cycle consisting of two hours of circulating water cleaning for circulating the acid aqueous solution for two hours and one hour of immersion cleaning for standing thereafter.
［比較例２］
比較例１において、常温超純水洗浄に先立ち、実施例２と同様の酸洗浄工程を実施したこと以外は同様にして膜モジュールの洗浄を行い、酸洗浄後のＣｌ−残留濃度の経時変化と、常温超純水洗浄開始時ないし開始後のＣａ２＋溶出濃度を調べ、結果を表２に示した。
[Comparative Example 2]
In Comparative Example 1, prior to cold ultrapure water cleaning, except that was carried out in the same manner as acid cleaning steps as in Example 2 was washed in membrane module in the same manner, Cl after acid washing - and aging of the residual concentration The Ca 2+ elution concentration at the start or after the start of room temperature ultrapure water cleaning was examined, and the results are shown in Table 2.
以上の結果から、高温純水洗浄工程を行わなかった比較例１では、高温純水洗浄工程を行った実施例１に対して、洗浄時間を相当に長くしないと、Ｃｌ−残留濃度、Ｃａ２＋溶出濃度を十分に低減させることができないことが分かる。 From the above results, in Comparative Example 1 was not carried out a high-temperature pure water washing step, with respect to Example 1 was carried out a high-temperature pure water washing process, unless the cleaning time was considerably prolonged, Cl - residual concentration, Ca 2+ It can be seen that the elution concentration cannot be reduced sufficiently.
［実施例３］
実施例２において、酸洗浄工程を２日、高温純水洗浄工程を１４日、常温超純水洗浄工程を１４日行ったこと以外は同様にして膜モジュールの洗浄を行ったところ、洗浄排水の水質は以下の通りとなり、ＵＦ膜を高清浄度に洗浄することができた。
[Example 3]
In Example 2, the membrane module was cleaned in the same manner except that the acid cleaning step was performed for 2 days, the high-temperature pure water cleaning step for 14 days, and the room temperature ultrapure water cleaning step for 14 days. The water quality was as follows, and the UF membrane could be washed with high cleanliness.
比抵抗：１８．２ＭΩ・ｃｍ
ＴＯＣ：０．８ｎｇ／Ｌ
金属イオン：０．５ｎｇ／Ｌ
アニオン：１．０ｎｇ／Ｌ
Specific resistance: 18.2 MΩ · cm
TOC: 0.8 ng / L
Metal ion: 0.5 ng / L
Anion: 1.0 ng / L
１ 原水貯留槽
３ 紫外線照射器
４ イオン交換塔
５ 限外濾過膜分離装置
６ 限外濾過膜
DESCRIPTION OF SYMBOLS 1 Raw
Claims (10)
前記濾過膜を７０℃以上の純水で洗浄する高温純水洗浄工程と、該高温純水洗浄工程の後に、該濾過膜を常温の超純水で洗浄する超純水洗浄工程とを有し、
前記高温純水洗浄工程における前記純水が、比抵抗；１７ＭΩ・ｃｍ以上、微粒子（１ｍＬ中、０．１μｍ径以上の微粒子数）；５個以下、微生物（１Ｌ中微生物数）；１０個以下、有機物（ＴＯＣ）；１０μｇ／Ｌ以下の純水であり、前記超純水洗浄工程における前記超純水が、比抵抗；１８ＭΩ・ｃｍ以上、微粒子（１ｍＬ中、０．１μｍ径以上の微粒子数）；１個以下、微生物（１Ｌ中微生物数）；１個以下、有機物（ＴＯＣ）；５μｇ／Ｌ以下の超純水であり、
前記高温純水洗浄工程が、通水洗浄と浸漬洗浄とを交互に繰り返し実施するものであり、
前記超純水洗浄工程における洗浄排水の水質項目が、比抵抗：１８ＭΩ・ｃｍ以上、ＴＯＣ：１０００ｎｇ／Ｌ以下、金属イオン：０．５ｎｇ／Ｌ以下、アニオン：５ｎｇ／Ｌ以下となったときに、前記濾過膜の洗浄を終了することを特徴とする濾過膜の洗浄方法。 A method of preliminarily washing a filtration membrane used for ultrapure water production prior to use in an ultrapure water production process,
A high-temperature pure water cleaning step of cleaning the filtration membrane with pure water of 70 ° C. or higher, and an ultra-pure water cleaning step of cleaning the filtration membrane with room-temperature ultra-pure water after the high-temperature pure water cleaning step. ,
The pure water in the high-temperature pure water washing step has a specific resistance of 17 MΩ · cm or more, fine particles (the number of fine particles having a diameter of 0.1 μm or more in 1 mL); 5 or less, microorganisms (the number of microorganisms in 1 L); 10 or less Organic matter (TOC): pure water of 10 μg / L or less, and the ultrapure water in the ultrapure water washing step has a specific resistance of 18 MΩ · cm or more, fine particles (the number of fine particles having a diameter of 0.1 μm or more in 1 mL) ); 1 or less, microorganisms (the number of microorganisms in 1 L); 1 or less, organic matter (TOC); 5 μg / L or less ultrapure water,
The hot pure water washing step state, and it is not repeatedly carried out and immersion cleaning and passing water washed alternately,
When the water quality of the cleaning wastewater in the ultrapure water cleaning process is specific resistance: 18 MΩ · cm or more, TOC: 1000 ng / L or less, metal ion: 0.5 ng / L or less, anion: 5 ng / L or less the method of cleaning a filtration membrane characterized that you end the cleaning of the filtration membrane.
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