JP2000271569A - Pure water production method - Google Patents
Pure water production methodInfo
- Publication number
- JP2000271569A JP2000271569A JP11081683A JP8168399A JP2000271569A JP 2000271569 A JP2000271569 A JP 2000271569A JP 11081683 A JP11081683 A JP 11081683A JP 8168399 A JP8168399 A JP 8168399A JP 2000271569 A JP2000271569 A JP 2000271569A
- Authority
- JP
- Japan
- Prior art keywords
- reverse osmosis
- osmosis membrane
- water
- treatment
- membrane treatment
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Separation Using Semi-Permeable Membranes (AREA)
- Physical Water Treatments (AREA)
Abstract
(57)【要約】
【課題】ホウ素、シリカ及びアルカリ成分などの含有量
が少なく、電気伝導率の小さい高水質の純水を効率よく
製造する方法を提供する。
【解決手段】原水を酸性条件下において、脱気処理及び
第１の逆浸透膜処理を行ったのち、そのpHを９.２以上
に調整して、さらに第２の逆浸透膜処理を行う純水の製
造方法において、第１の逆浸透膜処理で得られた処理水
のpH調整前又はpH調整後に、該処理水を脱酸素処理して
溶存酸素量を２００ppb以下にする純水の製造方法であ
る。
(57) [Problem] To provide a method for efficiently producing high-quality pure water having a low electric conductivity with a low content of boron, silica, an alkali component and the like. SOLUTION: Raw water is subjected to a deaeration treatment and a first reverse osmosis membrane treatment under acidic conditions, the pH thereof is adjusted to 9.2 or more, and further a second reverse osmosis membrane treatment is carried out. In the method for producing water, before or after adjusting the pH of the treated water obtained by the first reverse osmosis membrane treatment, the treated water is deoxygenated to reduce the dissolved oxygen content to 200 ppb or less. It is.
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、純水の製造方法の
改良に関する。さらに詳しくは、本発明は、多段逆浸透
膜処理により、ホウ素、シリカ及びアルカリ成分などの
含有量が少なく、電気伝導率の小さい高水質の純水を効
率よく製造する方法に関するものである。[0001] The present invention relates to an improvement in a method for producing pure water. More specifically, the present invention relates to a method for efficiently producing high-quality pure water having a low content of boron, silica, an alkali component and the like and a small electric conductivity by a multistage reverse osmosis membrane treatment.
【０００２】[0002]
【従来の技術】逆浸透膜による脱塩において、脱塩率は
逆浸透膜の種類によってほぼ決まるので、逆浸透膜に供
給する水の水質によって透過水として得られる脱塩水の
水質が左右される。高いpH条件下で逆浸透膜を用いて脱
塩する場合、ホウ素、シリカ、有機酸などは、pHの上昇
に応じて解離しやすくなり、イオン化した物質は逆浸透
膜で分離することができる。このために、中性条件下で
は除去できない物質も、高pH条件とすれば逆浸透膜によ
る除去が可能となる。例えば、Ｓｅｍｉｃｏｎｄｕｃｔ
ｏｒ Ｐｕｒｅ Ｗａｔｅｒ ａｎｄ Ｃｈｅｍｉｃａｌ
Ｃｏｎｆｅｒｅｎｃｅ（１９９７年）予稿集、第１〜１
９頁には、逆浸透膜への供給水のpHを１０とすることに
より、通常は３０％程度であるホウ素の透過率を１.５
％まで低下させ得ることが報告されている。また、第４
７回全国水道研究発表会（平成８年５月）予稿集、第２
５８〜２５９頁には、逆浸透膜への供給水のpHを１０以
上とすることにより、ホウ素の排除率が高くなることが
報告されている。しかし、供給水のpHを高めるために
は、アルカリ剤を多量に添加することが必要なので、逆
浸透膜への供給水の塩類濃度が上昇し、透過水に含まれ
る塩類濃度も上昇し、水質の低下を招くことになる。す
なわち、このような方法によれば、pH１０のような高pH
条件とする際に添加するアルカリ剤の量が多く、ナトリ
ウムイオンやアンモニウムイオンなどのアルカリ成分が
逆浸透膜の透過水にリークするという問題がある。とこ
ろで、原水の二段逆浸透膜処理による純水の製造方法と
して、例えば第１の逆浸透膜処理後、処理水にアルカリ
を添加し、これを第２の逆浸透膜処理を行う方法（特開
昭６１−４５９１号公報）、第１の逆浸透膜処理後、処
理水を膜脱気処理したのち、第２の逆浸透膜処理を行う
方法（特開平５−２２０４８０号公報）などが提案され
ている。しかしながら、これらの方法で得られた純水
は、水質的に必ずしも十分に満足しうるものではない。2. Description of the Related Art In desalination using a reverse osmosis membrane, the desalination rate is substantially determined by the type of the reverse osmosis membrane. Therefore, the quality of demineralized water obtained as permeate depends on the quality of water supplied to the reverse osmosis membrane. . When desalting using a reverse osmosis membrane under high pH conditions, boron, silica, organic acids, and the like are easily dissociated as the pH increases, and ionized substances can be separated by the reverse osmosis membrane. For this reason, substances that cannot be removed under neutral conditions can be removed by the reverse osmosis membrane under high pH conditions. For example, Semiconductor
or Pure Water and Chemical
Conference (1997) Proceedings, Nos. 1-1
On page 9, by setting the pH of the water supplied to the reverse osmosis membrane to 10, the permeability of boron, which is usually about 30%, is increased to 1.5.
% Can be reported. Also, the fourth
Proceedings of the 7th National Water Research Conference (May 1996), 2nd
On pages 58 to 259, it is reported that by setting the pH of the water supplied to the reverse osmosis membrane to 10 or more, the rejection of boron is increased. However, in order to increase the pH of the feed water, it is necessary to add a large amount of an alkaline agent, so that the salt concentration of the feed water to the reverse osmosis membrane increases, the salt concentration of the permeate increases, and the water quality increases. Will be reduced. That is, according to such a method, a high pH such as pH 10 can be obtained.
There is a problem that a large amount of an alkali agent is added under the conditions, and alkali components such as sodium ions and ammonium ions leak into permeated water of the reverse osmosis membrane. By the way, as a method for producing pure water by two-stage reverse osmosis membrane treatment of raw water, for example, a method of adding an alkali to treated water after the first reverse osmosis membrane treatment and subjecting the treated water to a second reverse osmosis membrane treatment (particularly, Japanese Patent Laid-Open No. Sho 61-4591), a method of performing a second reverse osmosis membrane treatment after treating the treated water with a membrane after degassing the first reverse osmosis membrane, and the like (Japanese Patent Laid-Open No. 5-220480). Have been. However, pure water obtained by these methods is not always satisfactory in terms of water quality.
【０００３】[0003]
【発明が解決しようとする課題】本発明は、このような
事情のもとで、ホウ素、シリカ及びアルカリ成分などの
含有量が少なく、電気伝導率の小さい高水質の純水を効
率よく製造する方法を提供することを目的としてなされ
たものである。SUMMARY OF THE INVENTION Under such circumstances, the present invention efficiently produces high-quality pure water having a low content of boron, silica, an alkali component and the like and a small electric conductivity. It is intended to provide a method.
【０００４】[0004]
【課題を解決するための手段】本発明者グループは、高
水質の純水を効率よく製造するために鋭意研究を重ね、
先にホウ素含有水を酸性条件とし、脱気処理と逆浸透膜
処理を行って、水中に共存する炭酸やアンモニアなどを
除去したのち、pH９.２以上の高アルカリ条件として逆
浸透膜処理することにより、pH調整のためのアルカリ剤
の添加量を減少し、逆浸透膜からのアルカリ成分のリー
ク量を低減し得ることを見出した（特願平１０−７７７
２８号）。本発明者は、さらに検討を進めた結果、第１
の逆浸透膜処理で得られた処理水を脱酸素処理したの
ち、高アルカリ性にpH調整するか、あるいは高アルカリ
性にpH調整したのち、脱酸素処理し、pH９.２以上で、
かつ溶存酸素量が２００ppb以下の処理水を、さらに第
２の逆浸透膜処理することにより、一層優れた水質の純
水が得られることを見出し、この知見に基づいて本発明
を完成するに至った。すなわち、本発明は、（１）原水
を酸性条件下において、脱気処理及び第１の逆浸透膜処
理を行ったのち、そのpHを９.２以上に調整して、さら
に第２の逆浸透膜処理を行う純水の製造方法において、
第１の逆浸透膜処理で得られた処理水のpH調整前又はpH
調整後に、該処理水を脱酸素処理して溶存酸素量を２０
０ppb以下にすることを特徴とする純水の製造方法、を
提供するものである。さらに、本発明の好ましい態様と
して、（２）酸性条件が、pH６以下である第(１)項記載
の純水の製造方法、及び、（３）pHを９.２以上に、か
つ溶存酸素量を２００ppb以下に調整した処理水の第２
の逆浸透膜処理を一段又は二段で行う第(１)、(２)項記
載の純水の製造方法、を挙げることができる。Means for Solving the Problems The inventor's group has conducted intensive studies to efficiently produce high-quality pure water,
Degassing treatment and reverse osmosis membrane treatment are first performed under acidic conditions with boron-containing water to remove carbonic acid and ammonia which coexist in the water, and then reverse osmosis treatment is performed under highly alkaline conditions of pH 9.2 or more. As a result, it has been found that the amount of an alkaline agent added for pH adjustment can be reduced, and the leak amount of an alkaline component from a reverse osmosis membrane can be reduced (Japanese Patent Application No. 10-777).
No. 28). The present inventor further studied and found that the first
The treated water obtained by the reverse osmosis membrane treatment is deoxygenated, and then the pH is adjusted to be highly alkaline, or the pH is adjusted to be highly alkaline, and then deoxygenated, and the pH is adjusted to 9.2 or more.
Further, it has been found that pure water having better water quality can be obtained by further treating the treated water having an amount of dissolved oxygen of 200 ppb or less with the second reverse osmosis membrane. Based on this finding, the present invention has been completed. Was. That is, the present invention provides (1) a method in which raw water is subjected to degassing treatment and first reverse osmosis membrane treatment under acidic conditions, and then its pH is adjusted to 9.2 or more, and then the second reverse osmosis treatment is performed. In a method for producing pure water for performing membrane treatment,
Before pH adjustment or pH of treated water obtained by the first reverse osmosis membrane treatment
After the adjustment, the treated water is deoxygenated to reduce the dissolved oxygen content to 20%.
A method for producing pure water, characterized in that the water content is 0 ppb or less. Further, as preferred embodiments of the present invention, (2) the method for producing pure water according to (1), wherein the acidic condition is pH 6 or less; and (3) the pH is 9.2 or more, and the amount of dissolved oxygen is Of treated water whose water content has been adjusted to 200 ppb or less
(1) and (2) wherein the reverse osmosis membrane treatment is carried out in one or two stages.
【０００５】[0005]
【発明の実施の形態】本発明の純水の製造方法において
は、原水を酸性条件下で、脱気処理及び第１の逆浸透膜
処理を行ったのち、脱酸素処理及びpH調整を行い、さら
に第２の逆浸透膜処理を行う。酸性条件とした原水の脱
気処理及び第１の逆浸透膜処理の順序には特に制限はな
く、脱気処理に続いて第１の逆浸透膜処理することがで
き、あるいは逆に第１の逆浸透膜処理に続いて脱気処理
することもできる。本発明方法に用いる原水は、凝集沈
殿、活性炭処理などの処理を行って、濁度などを除いた
いわゆる一次純水装置の原水に適した水質を有するもの
が好ましい。本発明方法において、この原水を酸性条件
とする方法には特に制限はなく、例えば、塩酸、硫酸な
どの酸の添加により酸性とする方法、あるいはＨ型のカ
チオン交換樹脂を用いる方法や電解法による方法など、
いずれの方法も用いることができる。酸性条件として
は、pHが好ましくは６以下、より好ましくは５.５以
下、さらに好ましくは５以下である。脱気処理に使用さ
れる装置としては特に制限はなく、例えば、脱炭酸塔、
真空脱気塔、窒素脱気塔、膜脱気装置などを挙げること
ができる。これらの脱気処理装置の中で、特に原水と空
気との向流接触による脱炭酸塔が好適である。酸性条件
下で脱気処理することにより、原水中に含まれる炭酸イ
オン及び重炭酸イオンを炭酸ガスとして除去することが
できる。水中に炭酸イオン及び重炭酸イオンが存在する
と、炭酸イオン及び重炭酸イオンはpHの緩衝作用が大き
いので、後工程でpHを９.２以上に調整するために必要
な水酸化ナトリウムや水酸化カリウムなどのアルカリ剤
の添加量が多くなり、第２の逆浸透膜処理におけるアル
カリのリーク量が多くなる。本発明方法においては、原
水を酸性条件下において脱気処理して炭酸を除去するの
で、pHを９.２以上に調整するために必要なアルカリ剤
の添加量が少なく、第２の逆浸透膜処理におけるアルカ
リのリーク量を大幅に減少することができる。本発明方
法においては、原水を前記のように酸性条件として、第
１の逆浸透膜処理を行う。水中にアンモニアが含まれる
場合、酸性条件として第１の逆浸透膜処理することによ
り、アンモニアをアンモニウムイオンの形態として、水
中より除去することができる。この第１の逆浸透膜処理
における逆浸透膜の種類及び運転条件については特に制
限はないが、pHは５.５以下が好ましい。このpHが５.５
を超えるとシリカの溶解量の増加が少なく、水回収率が
低下するおそれがある。また、pHが低すぎると後工程で
のアルカリ剤の添加量が多くなり、好ましくない。水回
収率及びアルカリ剤の添加量などを考慮すると、このpH
は４.５〜５.０の範囲がより好ましい。BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing pure water according to the present invention, a raw water is subjected to a degassing treatment and a first reverse osmosis membrane treatment under acidic conditions, and then subjected to a deoxygenation treatment and a pH adjustment. Further, a second reverse osmosis membrane treatment is performed. There is no particular limitation on the order of the deaeration treatment of the raw water under acidic conditions and the first reverse osmosis membrane treatment, and the first reverse osmosis membrane treatment can be performed subsequent to the deaeration treatment, or conversely, the first reverse osmosis membrane treatment can be performed. Following the reverse osmosis membrane treatment, a degassing treatment can also be performed. The raw water used in the method of the present invention is preferably one having a water quality suitable for raw water of a so-called primary pure water apparatus, which is subjected to treatment such as coagulation sedimentation and activated carbon treatment to remove turbidity and the like. In the method of the present invention, there is no particular limitation on the method of making the raw water acidic. For example, a method of making the raw water acidic by adding an acid such as hydrochloric acid or sulfuric acid, a method of using an H-type cation exchange resin, or an electrolytic method How
Either method can be used. As the acidic condition, the pH is preferably 6 or less, more preferably 5.5 or less, and still more preferably 5 or less. There is no particular limitation on the apparatus used for the deaeration treatment, for example, a decarbonation tower,
Examples include a vacuum degassing tower, a nitrogen degassing tower, and a membrane degassing apparatus. Among these deaeration apparatuses, a decarbonation tower by countercurrent contact between raw water and air is particularly suitable. By degassing under acidic conditions, carbonate ions and bicarbonate ions contained in the raw water can be removed as carbon dioxide gas. If carbonate ions and bicarbonate ions are present in the water, the carbonate ions and bicarbonate ions have a large buffering effect on the pH. Therefore, sodium hydroxide and potassium hydroxide necessary for adjusting the pH to 9.2 or more in a later step are used. For example, the amount of the alkali agent added increases, and the amount of alkali leakage in the second reverse osmosis membrane treatment increases. In the method of the present invention, since the raw water is degassed under acidic conditions to remove carbonic acid, the amount of the alkali agent required to adjust the pH to 9.2 or higher is small, and the second reverse osmosis membrane is used. The amount of leakage of alkali in the treatment can be greatly reduced. In the method of the present invention, the first reverse osmosis membrane treatment is performed under the acidic condition of the raw water as described above. When ammonia is contained in the water, the ammonia can be removed from the water in the form of ammonium ions by performing the first reverse osmosis membrane treatment under acidic conditions. The type and operating conditions of the reverse osmosis membrane in the first reverse osmosis membrane treatment are not particularly limited, but the pH is preferably 5.5 or less. This pH is 5.5
If it exceeds 300, the increase in the amount of silica dissolved is small, and the water recovery rate may decrease. On the other hand, if the pH is too low, the amount of the alkali agent added in the subsequent step increases, which is not preferable. Considering the water recovery rate and the amount of alkaline agent added, this pH
Is more preferably in the range of 4.5 to 5.0.
【０００６】脱気処理により、原水のpHが上昇し、上記
範囲より高くなった場合には、酸を添加し、pHを上記範
囲に調整してもよい。なお、酸性条件下における脱気処
理を行ったのち第１の逆浸透膜処理する方法は、酸性条
件とするために添加した酸成分と、脱気処理により除去
しきれずに残存する炭酸イオンと重炭酸イオンも、逆浸
透膜処理において除去することができるので、有利であ
る。なお、この第１の逆浸透膜処理は、必要に応じ、多
段に逆浸透膜を設けて行ってもよい。逆浸透膜を多段に
設ける場合は、前段の逆浸透膜の透過水を後段の逆浸透
膜の供給水とする。本発明方法においては、前記第１の
逆浸透膜処理により、得られた処理水（透過水）を必要
に応じてその後段に設けられる非再生型のカルシウムイ
オン除去装置に供給してもよい。この非再生型のカルシ
ウムイオン除去装置としては、例えばＮａ型やＨ型の非
再生カチオン交換樹脂又はキレート樹脂などを充填した
装置を挙げることができる。本発明方法においては、こ
のようにして原水を酸性条件とし、脱気処理及び第１の
逆浸透膜処理を行ったのち、脱酸素処理及びpH調整を行
う。この脱酸素処理及びpH調整の順序については特に制
限はないが、脱酸素処理後にpH調整を行うのが有利であ
る。脱酸素処理としては特に制限はなく、例えば膜脱気
法、真空脱気法、窒素脱気法及び触媒法などいずれも用
いることができる。本発明方法においては、このような
脱酸素処理により、処理水の溶存酸素量を２００ppb以
下にすることが必要である。溶存酸素量を２００ppb以
下にすることによって、後工程の第２の逆浸透膜処理に
おいて、ナトリウムイオンなどのアルカリ成分のリーク
を抑制することができ、高水質の純水を得ることができ
る。一方、pH調整は、処理水のpHを９.２以上に調整す
ることが必要であり、その方法については特に制限はな
く、例えば、水酸化ナトリウム、水酸化カリウムなどの
アルカリ水溶液を添加する方法や、強塩基性アニオン交
換樹脂と接触させる方法、あるいは電解法などを挙げる
ことができる。アルカリ水溶液を添加する方法として
は、例えば、撹拌機付きのpH調整槽を設けたり、通水ラ
インにアルカリ水溶液注入口を設け、その下流側にスタ
チックミキサーなどを設置する方法などを用いることが
できる。このpHは、特に９.５〜１１の範囲に調整する
のが好ましい。本発明方法においては、このようにし
て、溶存酸素量が２００ppb以下に、かっpHが９.２以上
に調整された処理水を、第２の逆浸透膜処理する。この
第２の逆浸透膜処理に用いられる逆浸透膜は、長期的に
pH１０以上となっても劣化を受けない耐アルカリ性逆浸
透膜であることが好ましい。この場合、アルカリ条件の
供給水のpHよりも、濃縮水の方がpHが高くなるので、濃
縮水のpHを考慮して耐アルカリ性逆浸透膜を選択する必
要がある。このような耐アルカリ性逆浸透膜としては、
例えば、pH１１まで長期耐久性のあるものとして市販さ
れているＦｉｌｍＴｅｃ社製のＦＩＬＭＴＥＣ ｔｙｐ
ｅ ＦＴ３０などや、pH１０まで長期耐久性のあるもの
として市販されている日東電工(株)製のＥＳ２０、ＥＳ
１０、ＮＴＲ７５９、東レ(株)製のＳＵ７００などのポ
リアミド系の膜などを挙げることができる。When the pH of the raw water rises due to the degassing treatment and becomes higher than the above range, an acid may be added to adjust the pH to the above range. The first reverse osmosis membrane treatment after the degassing treatment under acidic conditions is carried out by mixing the acid component added for the acidic condition with the remaining carbonate ions that cannot be completely removed by the degassing treatment. Advantageously, carbonate ions can also be removed in the reverse osmosis membrane treatment. The first reverse osmosis membrane treatment may be performed by providing a reverse osmosis membrane in multiple stages, if necessary. When the reverse osmosis membrane is provided in multiple stages, the permeated water of the first stage reverse osmosis membrane is used as the supply water of the second stage reverse osmosis membrane. In the method of the present invention, the treated water (permeate) obtained by the first reverse osmosis membrane treatment may be supplied to a non-regeneration-type calcium ion removing device provided at a subsequent stage as necessary. As the non-regenerating type calcium ion removing apparatus, for example, an apparatus filled with a non-regenerating cation exchange resin or a chelating resin of Na type or H type can be mentioned. In the method of the present invention, the deaeration treatment and the first reverse osmosis membrane treatment are performed after the raw water is placed under acidic conditions, and then the deoxygenation treatment and the pH adjustment are performed. The order of the deoxidation treatment and the pH adjustment is not particularly limited, but it is advantageous to adjust the pH after the deoxygenation treatment. There is no particular limitation on the deoxygenation treatment, and for example, any of a membrane degassing method, a vacuum degassing method, a nitrogen degassing method, and a catalytic method can be used. In the method of the present invention, it is necessary to reduce the dissolved oxygen content of the treated water to 200 ppb or less by such a deoxidation treatment. By setting the amount of dissolved oxygen to 200 ppb or less, leakage of an alkali component such as sodium ions can be suppressed in the second reverse osmosis membrane treatment in the subsequent step, and high-quality pure water can be obtained. On the other hand, for pH adjustment, it is necessary to adjust the pH of the treated water to 9.2 or more, and there is no particular limitation on the method. For example, a method of adding an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide is used. And a method of contacting with a strongly basic anion exchange resin, or an electrolytic method. As a method of adding the alkaline aqueous solution, for example, a method of providing a pH adjusting tank with a stirrer, providing an alkaline aqueous solution injection port in a water flow line, and installing a static mixer or the like downstream thereof may be used. it can. It is particularly preferable to adjust this pH to the range of 9.5 to 11. In the method of the present invention, the treated water having the dissolved oxygen content adjusted to 200 ppb or less and the pH adjusted to 9.2 or more is subjected to the second reverse osmosis membrane treatment. The reverse osmosis membrane used for the second reverse osmosis membrane treatment has a long term
It is preferable to use an alkali-resistant reverse osmosis membrane that does not undergo deterioration even when the pH becomes 10 or more. In this case, since the concentrated water has a higher pH than the supply water under alkaline conditions, it is necessary to select an alkali-resistant reverse osmosis membrane in consideration of the pH of the concentrated water. As such an alkali-resistant reverse osmosis membrane,
For example, FILMTEC type manufactured by FilmTec, which is commercially available as having long-term durability up to pH 11
e Nitto Denko Corporation's ES20 and ES, which are commercially available as FT30, etc., and have long-term durability up to pH 10
10, NTR759, and a polyamide-based film such as SU700 manufactured by Toray Industries, Inc.
【０００７】本発明においては、この第２の逆浸透膜処
理は、逆浸透膜を一段設けて行ってもよいし、多段、好
ましくは二段設けて行ってもよい。逆浸透膜を多段に設
ける場合は、前記したように、前段の逆浸透膜の透過水
を後段の逆浸透膜の供給水とする。この第２の逆浸透膜
処理において、逆浸透膜を多段に設けた場合、供給水中
のアルカリ成分は濃縮水中に濃縮され、後段の逆浸透膜
への供給水となる前段の逆浸透膜の透過水のpHは低くな
るので、前段の逆浸透膜の透過水にアルカリ剤を添加し
てpH調整を行ったのち、後段の逆浸透膜に供給すること
が好ましい。また、アルカリ成分が濃縮された前段の逆
浸透膜の濃縮水は、原水や逆浸透膜への供給水に添加し
て再利用することができ、あるいは、別工程において、
アルカリ剤として利用することもできる。本発明方法に
おいては、このようにして第２の逆浸透膜処理により得
られた処理水（透過水）は、脱イオン装置に通水して、
純水の仕上げを行うことができる。この脱イオン装置と
しては特に制限はなく、例えば再生型又は非再生型の混
床イオン交換装置、電気再生型脱イオン装置、正荷電逆
浸透膜などを用いることができる。再生型又は非再生型
の混床イオン交換装置としては、例えば再生型又は非再
生型の公知の強酸性陽イオン交換樹脂と強塩基性陰イオ
ン交換樹脂を充填したイオン交換装置が挙げられる。電
気再生型脱イオン装置としては、公知のものを用いるこ
とができ、このものは薬品による再生が不要であり、小
型で大容量を有しており、経済的に純水を製造すること
ができる。また、正荷電逆浸透膜は、膜表面のポリアミ
ド系のスキン層をカチオン化した逆浸透膜である。この
ような正荷電逆浸透膜としては、例えば、市販されてい
る日東電工(株)のＥＳ１０Ｃや、東レ(株)のＳＵ９００
などを用いることができる。また、本発明方法において
は、所望により、第１の逆浸透膜処理における濃縮水
を、さらに別途逆浸透膜処理し、その処理水（透過水）
と第２の逆浸透膜処理における濃縮水とを混合し、第１
の逆浸透膜処理工程又はその前段に設けられた脱気処理
工程へ返送して、純水の回収率の向上を図ることができ
る。次に、本発明の好適な実施態様を添付図面に従って
説明すると、図１及び図２は、それぞれ本発明方法を実
施するための異なる例の工程系統図である。図１におい
ては、原水は酸が添加されて酸性化されたのち、脱気処
理工程１に供給されて脱気処理される。脱気処理水は第
１の逆浸透膜処理工程２に供給され、得られた処理水
（透過水）は脱酸素処理工程３に供給されて、溶存酸素
量が２００ppb以下に脱酸素処理される。次に、この脱
酸素処理水はアルカリ剤が添加されてpH９.２以上に調
整されたのち、第２の逆浸透膜処理工程４に供給され、
その処理水（透過水）は、さらに脱イオン装置５に供給
されて、純水に仕上げられる。一方、図２においては、
メインの流れは前記図１の場合と同様であるが、第１の
逆浸透膜処理工程２における濃縮水を、別途設けられた
逆浸透膜処理工程６に供給し、得られた処理水（透過
水）を、第２の逆浸透膜処理工程４における濃縮水と混
合して、脱気処理工程１又は第１の逆浸透膜処理工程２
へ返送する。In the present invention, the second reverse osmosis membrane treatment may be performed by providing a reverse osmosis membrane in one stage, or may be performed in multiple stages, preferably in two stages. When the reverse osmosis membrane is provided in multiple stages, as described above, the permeated water of the first stage reverse osmosis membrane is used as the supply water of the second stage reverse osmosis membrane. In the second reverse osmosis membrane treatment, when the reverse osmosis membrane is provided in multiple stages, the alkali component in the feed water is concentrated in the concentrated water, and the permeation of the reverse osmosis membrane in the former stage becomes supply water to the latter reverse osmosis membrane. Since the pH of water becomes low, it is preferable to adjust the pH by adding an alkali agent to the permeated water of the reverse osmosis membrane in the former stage, and then supply it to the reverse osmosis membrane in the latter stage. Further, the concentrated water of the reverse osmosis membrane in the former stage in which the alkali component is concentrated can be reused by being added to raw water or water supplied to the reverse osmosis membrane, or in another step,
It can also be used as an alkaline agent. In the method of the present invention, the treated water (permeate) thus obtained by the second reverse osmosis membrane treatment is passed through a deionizer,
Pure water finishing can be performed. The deionization device is not particularly limited, and for example, a regeneration type or non-regeneration type mixed bed ion exchange device, an electric regeneration type deionization device, a positively charged reverse osmosis membrane, or the like can be used. Examples of the regenerated or non-regenerated mixed bed ion exchange device include an ion exchange device filled with a known regenerative or non-regeneration type strongly acidic cation exchange resin and a strongly basic anion exchange resin. As the electric regeneration type deionization apparatus, a known apparatus can be used. This apparatus does not require regeneration by a chemical, has a small size, has a large capacity, and can economically produce pure water. . The positively charged reverse osmosis membrane is a reverse osmosis membrane obtained by cationizing a polyamide skin layer on the membrane surface. Examples of such positively charged reverse osmosis membranes include commercially available ES10C of Nitto Denko Corporation and SU900 of Toray Industries, Inc.
Etc. can be used. In the method of the present invention, if necessary, the concentrated water in the first reverse osmosis membrane treatment is further subjected to a reverse osmosis membrane treatment, and the treated water (permeated water)
And the concentrated water in the second reverse osmosis membrane treatment,
To the reverse osmosis membrane treatment step or the deaeration treatment step provided in the preceding stage to improve the recovery rate of pure water. Next, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. FIGS. 1 and 2 are process flow diagrams of different examples for carrying out the method of the present invention. In FIG. 1, after the raw water is acidified by adding an acid, it is supplied to a deaeration step 1 to be deaerated. The degassed water is supplied to a first reverse osmosis membrane treatment step 2, and the obtained treated water (permeated water) is supplied to a deoxygenation treatment step 3 to be deoxygenated to a dissolved oxygen amount of 200 ppb or less. . Next, the deoxygenated water is adjusted to pH 9.2 or more by adding an alkaline agent, and then supplied to the second reverse osmosis membrane treatment step 4,
The treated water (permeated water) is further supplied to the deionizer 5 to be finished into pure water. On the other hand, in FIG.
The main flow is the same as that of FIG. 1 except that the concentrated water in the first reverse osmosis membrane treatment step 2 is supplied to a separately provided reverse osmosis membrane treatment step 6, and the obtained treated water (permeate) Water) is mixed with the concentrated water in the second reverse osmosis membrane treatment step 4, and the deaeration treatment step 1 or the first reverse osmosis membrane treatment step 2 is performed.
Return to
【０００８】[0008]
【実施例】次に、本発明を実施例により、さらに詳細に
説明するが、本発明は、これらの例によってなんら限定
されるものではない。 実施例１ 厚木市水（pH７.６、電気伝導率１５０μＳ／cm、Ｓｉ
Ｏ2 ２６ppm）を塩酸でpH４.９に調整したのち、ネッ
トリングを１ｍの高さに充填した脱炭酸塔にＬＶ３０ｍ
／hrで通水すると共に、空気をガス／液比２０になるよ
うに向流接触させて、脱炭酸処理を行った。次いで、こ
の処理水を第１の逆浸透膜［日東電工(株)製、「ＥＳ−
２０」の４インチ逆浸透膜が２本シリーズに連結したも
の］に通水した。この際の処理量は０.５ｍ3／hr、給水
pHは５.１、濃縮水のpHは５.４、回収率は８０％であっ
た。この第１の逆浸透膜処理水を、圧力３５Ｔｏｒｒ、
スイープガス量０.１Ｎｍ3／hr（窒素ガス）の条件で膜
脱気を行い［ヘキストジヤパン社製、４インチの「Ｌｉ
ｑｕｉ−Ｃｅｌ(登録商標)」１本使用］、脱酸素処理し
た。この操作により、溶存酸素量は１５０〜２００ppb
となった。次に、この脱酸素処理水を、水酸化ナトリウ
ムでpH１０.０に調整したのち、第２の逆浸透膜［日東
電工(株)製、４インチの「ＥＳ−２０」１本使用］に通
水した。この際、回収率は９０％、処理水量は０.２８
ｍ3／hrであり、また、処理水中のナトリウムイオンの
含有量は１７０〜１８０ppbであった。 比較例１ 実施例１において、第１の逆浸透膜への給水に、水酸化
ナトリウムを添加して、pHを６.８に調整した以外は、
実施例１と同様な操作を行ったところ、第２の逆浸透膜
処理水中のナトリウムイオンの含有量は２００〜２７０
ppbであった。 比較例２ 実施例１において、膜脱気による脱酸素処理の代わり
に、実施例１で用いた脱炭酸塔と同じものを用いて脱酸
素処理を行った以外は、実施例１と同様な操作を行っ
た。その結果、脱酸素処理後の処理水中の溶存酸素量は
４.２〜５.３ppmであり、また、第２の逆浸透膜処理水
中のナトリウムイオンの含有量は、２３０〜２４０ppb
であった。Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 Atsugi-shi water (pH 7.6, electric conductivity 150 μS / cm, Si
O 2 26 ppm) was adjusted to pH 4.9 with hydrochloric acid, and then LV 30 m was added to a decarbonation tower filled with a net ring at a height of 1 m.
/ Hr, and air was brought into countercurrent contact with the gas at a gas / liquid ratio of 20 to perform decarbonation treatment. Next, this treated water was used as a first reverse osmosis membrane [Nitto Denko Corporation, “ES-
20 "4-inch reverse osmosis membrane connected to two series]. At this time, the processing amount is 0.5 m 3 / hr, and water supply
The pH was 5.1, the pH of the concentrated water was 5.4, and the recovery was 80%. This first reverse osmosis membrane treated water was supplied at a pressure of 35 Torr,
The membrane was degassed under the conditions of a sweep gas amount of 0.1 Nm 3 / hr (nitrogen gas) [Hoechst Japan Ltd., 4 inch “Li”
qui-Cel (registered trademark) "was used.] By this operation, the dissolved oxygen amount becomes 150 to 200 ppb
It became. Next, the deoxygenated water is adjusted to pH 10.0 with sodium hydroxide, and then passed through a second reverse osmosis membrane [using one 4-inch “ES-20” manufactured by Nitto Denko Corporation]. Watered. At this time, the recovery rate was 90% and the amount of treated water was 0.28.
m 3 / hr, and the content of sodium ions in the treated water was 170 to 180 ppb. Comparative Example 1 In Example 1, except that sodium hydroxide was added to the water supply to the first reverse osmosis membrane to adjust the pH to 6.8.
When the same operation as in Example 1 was performed, the content of sodium ions in the second reverse osmosis membrane treated water was 200 to 270.
ppb. Comparative Example 2 The same operation as in Example 1 except that the deoxygenation treatment was performed using the same decarbonation tower as used in Example 1 instead of the deoxygenation treatment by membrane degassing in Example 1. Was done. As a result, the dissolved oxygen content in the treated water after the deoxygenation treatment was 4.2 to 5.3 ppm, and the sodium ion content in the second reverse osmosis membrane treated water was 230 to 240 ppb.
Met.
【０００９】[0009]
【発明の効果】本発明方法によれば、原水を酸性条件下
に脱気処理及び第１の逆浸透膜処理を行って、アンモニ
アや炭酸などを十分に除去しているので、pHを９.２以
上に調整するために添加するアルカリ剤の量を低減しう
ることから、また、脱酸素処理により、溶存酸素量を減
少させていることから、第２の逆浸透膜処理において、
リークするアルカリ成分量を減少させることができる。
したがって、本発明方法によれば、ホウ素、シリカ、ア
ルカリ成分などの含有量が少なく、電気伝導率の小さい
高水質の純水を効率よく製造することができる。According to the method of the present invention, raw water is subjected to degassing and first reverse osmosis membrane treatment under acidic conditions to sufficiently remove ammonia, carbonic acid and the like. In the second reverse osmosis membrane treatment, since the amount of the alkaline agent to be added for adjusting to 2 or more can be reduced, and the amount of dissolved oxygen is reduced by the deoxidation treatment,
The amount of leaking alkali component can be reduced.
Therefore, according to the method of the present invention, it is possible to efficiently produce high-quality pure water having a low content of boron, silica, an alkali component and the like and a small electric conductivity.
【図１】図１は、本発明方法を実施するための１例の工
程系統図である。FIG. 1 is a flow chart of an example for carrying out the method of the present invention.
【図２】図２は、本発明方法を実施するための別の例の
工程系統図である。FIG. 2 is a process flow diagram of another example for carrying out the method of the present invention.
１ 脱気処理工程 ２ 第１の逆浸透膜処理工程 ３ 脱酸素処理工程 ４ 第２の逆浸透膜処理工程 ５ 脱イオン装置 ６ 逆浸透膜処理工程 REFERENCE SIGNS LIST 1 deaeration treatment step 2 first reverse osmosis membrane treatment step 3 deoxygenation treatment step 4 second reverse osmosis membrane treatment step 5 deionizer 6 reverse osmosis membrane treatment step
Claims (1)
第１の逆浸透膜処理を行ったのち、そのpHを９.２以上
に調整して、さらに第２の逆浸透膜処理を行う純水の製
造方法において、第１の逆浸透膜処理で得られた処理水
のpH調整前又はpH調整後に、該処理水を脱酸素処理して
溶存酸素量を２００ppb以下にすることを特徴とする純
水の製造方法。1. After subjecting raw water to degassing and first reverse osmosis membrane treatment under acidic conditions, the pH of the raw water is adjusted to 9.2 or more, and then a second reverse osmosis membrane treatment is performed. In the method for producing pure water, before or after adjusting the pH of the treated water obtained by the first reverse osmosis membrane treatment, the treated water is deoxygenated to reduce the amount of dissolved oxygen to 200 ppb or less. Pure water production method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11081683A JP2000271569A (en) | 1999-03-25 | 1999-03-25 | Pure water production method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11081683A JP2000271569A (en) | 1999-03-25 | 1999-03-25 | Pure water production method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2000271569A true JP2000271569A (en) | 2000-10-03 |
Family
ID=13753166
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11081683A Pending JP2000271569A (en) | 1999-03-25 | 1999-03-25 | Pure water production method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2000271569A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004000919A (en) * | 2002-04-05 | 2004-01-08 | Kurita Water Ind Ltd | Demineralized water production equipment |
| JP2004167423A (en) * | 2002-11-21 | 2004-06-17 | Kurita Water Ind Ltd | Pure water production apparatus and pure water production method |
| JP2008080255A (en) * | 2006-09-28 | 2008-04-10 | Nippon Rensui Co Ltd | Pure water production equipment |
| RU2389693C2 (en) * | 2007-06-29 | 2010-05-20 | Закрытое акционерное общество "Конверсия" | Method of purifying highly mineralised water |
| JP2016112518A (en) * | 2014-12-16 | 2016-06-23 | 株式会社日立製作所 | Deoxidation apparatus, and production method of deoxidized water |
| WO2024075731A1 (en) * | 2022-10-04 | 2024-04-11 | 野村マイクロ・サイエンス株式会社 | Method for producing pure water from which boron has been removed, pure water production device, and ultrapure water production system |
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| JPH09192661A (en) * | 1996-01-17 | 1997-07-29 | Japan Organo Co Ltd | Ultrapure water producing device |
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| JPS6336890A (en) * | 1986-07-28 | 1988-02-17 | Kurita Water Ind Ltd | Apparatus for producing high-purity water |
| JPH06109207A (en) * | 1992-09-28 | 1994-04-19 | Mitsubishi Heavy Ind Ltd | Method of reducing dissolved oxygen in outlet vapor from boiler |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004000919A (en) * | 2002-04-05 | 2004-01-08 | Kurita Water Ind Ltd | Demineralized water production equipment |
| JP2004167423A (en) * | 2002-11-21 | 2004-06-17 | Kurita Water Ind Ltd | Pure water production apparatus and pure water production method |
| JP2008080255A (en) * | 2006-09-28 | 2008-04-10 | Nippon Rensui Co Ltd | Pure water production equipment |
| RU2389693C2 (en) * | 2007-06-29 | 2010-05-20 | Закрытое акционерное общество "Конверсия" | Method of purifying highly mineralised water |
| JP2016112518A (en) * | 2014-12-16 | 2016-06-23 | 株式会社日立製作所 | Deoxidation apparatus, and production method of deoxidized water |
| WO2024075731A1 (en) * | 2022-10-04 | 2024-04-11 | 野村マイクロ・サイエンス株式会社 | Method for producing pure water from which boron has been removed, pure water production device, and ultrapure water production system |
| JP7645850B2 (en) | 2022-10-04 | 2025-03-14 | 野村マイクロ・サイエンス株式会社 | Method for producing boron-removed pure water, pure water production equipment, ultrapure water production system |
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