JP3944973B2 - Reverse osmosis membrane treatment method - Google Patents
Reverse osmosis membrane treatment method Download PDFInfo
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- JP3944973B2 JP3944973B2 JP29556597A JP29556597A JP3944973B2 JP 3944973 B2 JP3944973 B2 JP 3944973B2 JP 29556597 A JP29556597 A JP 29556597A JP 29556597 A JP29556597 A JP 29556597A JP 3944973 B2 JP3944973 B2 JP 3944973B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/138—Water desalination using renewable energy
- Y02A20/144—Wave energy
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- Separation Using Semi-Permeable Membranes (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は逆浸透膜（ＲＯ膜）処理方法に係り、特に、ＲＯ膜分離装置の運転を停止することなく、ＲＯ膜分離装置の生産水量の低下や差圧上昇の要因となる膜汚染物を効果的に洗浄除去することができるＲＯ膜分離方法に関する。
【０００２】
【従来の技術】
近年、市水、井水等の脱塩方法として、ＲＯ膜処理法が広く採用されている。
【０００３】
このＲＯ膜処理では、ＲＯ膜分離装置の運転を継続することにより、ＲＯ膜に付着、堆積した膜汚染物により膜性能が低下し、生産水（膜透過水）量の低下や差圧の上昇が起こる。
【０００４】
この膜汚染物は、鉄やアルミニウム等の金属水酸化物、微生物のスライム、界面活性剤や高分子凝集剤等の有機物質、或いは、シリカや炭酸カルシウム等のスケール等であり、膜汚染で性能が低下したＲＯ膜は、当該汚染物に応じた薬品を用いる薬品洗浄で汚染物を洗浄除去することで性能を回復させることができる（「超純水の科学」リアライズ社第２７４頁〜第２７７頁）。
【０００５】
この膜洗浄法として、特開平７−１６５６６号公報には、ＲＯ膜等の分離膜をアルカリ洗浄することが記載されている。また、特公昭５２−１０７８５号公報には、ＲＯ膜分離装置にｐＨ９〜１３のアルカリ水を短時間通水することにより膜汚染物を洗浄除去する方法が記載されている。
【０００６】
【発明が解決しようとする課題】
従来の膜洗浄方法は、ＲＯ膜分離装置の運転を一旦停止し、別途設けた薬品洗浄用の循環タンクで、予め調整した洗浄薬品をＲＯ膜分離装置に循環通水するものであるため、洗浄運転時には膜透過水を得ることができない、洗浄操作が煩雑である、装置が複雑であるといった欠点がある。
【０００７】
特公昭５２−１０７８５号公報には、ｐＨ調整前のアルカリ性の被処理液を洗浄水として使用し得ることが記載されているが、やはり採水運転と洗浄運転とを交互に行うものであり、洗浄運転中には膜透過水を得ることができないという欠点がある。
【０００８】
本発明は上記従来の問題点を解決し、ＲＯ膜分離装置の運転を停止することなく、即ち採水を継続して、ＲＯ膜分離装置の生産水量の低下や差圧上昇の要因となる膜汚染物を効果的に洗浄除去することができるＲＯ膜処理方法を提供することを目的とする。
【０００９】
【課題を解決するための手段】
本発明のＲＯ膜処理方法は、ＲＯ膜分離装置に、中性条件で原水を供給し、膜透過水を処理水として取り出すＲＯ膜処理方法において、ＲＯ膜分離装置の連続運転中にＲＯ膜分離装置に供給される原水のｐＨを一時的に１０〜１２とするｐＨ調整を行い、該ｐＨ調整中も膜透過水を処理水として取り出し、該膜透過水をイオン交換装置でイオン交換処理することを特徴とする。
【００１０】
ＲＯ膜分離装置にｐＨ１０〜１２のアルカリ性の水を通水することにより、膜汚染物、特に、スライムや有機物等の膜汚染物を効果的に洗浄除去して膜性能を維持することができる。
【００１１】
本発明では、ＲＯ膜分離装置の運転中に一定の頻度で原水にアルカリを添加して給水すれば良く、洗浄用の循環タンクなどは不要である。また、このｐＨ調整中も膜透過水を処理水として採水するため、生産水量を高く維持することができる。
【００１２】
本発明において、上記ｐＨ調整は３〜１０日に一度の頻度で、１５〜３００分間行うのが好ましい。
【００１３】
このようにｐＨ調整中も採水を維持することで処理水の水質が低下する恐れがあるが、ＲＯ膜分離装置の後段にイオン交換装置を設け、ＲＯ膜透過水をイオン交換処理することにより、処理水質を維持することができる。
【００１４】
【発明の実施の形態】
以下に図面を参照して本発明の実施の形態を詳細に説明する。
【００１５】
図１は本発明のＲＯ膜処理方法の実施の形態を示す系統図である。
【００１６】
この方法は、原水、例えば工業用水、市水、井水等の凝集、加圧浮上、濾過処理水をＲＯ膜分離装置１及びイオン交換装置２に順次通水して処理する装置に本発明方法を適用したものであり、原水の供給ラインには、アルカリタンク３Ａ及び薬注ポンプ３Ｂよりなるアルカリ注入手段３と、酸タンク４Ａ及び薬注ポンプ４Ｂよりなる酸注入手段４と、攪拌機（スタティックミキサー）５と、ｐＨ計６が設けられると共に、ｐＨの自動制御のためのＰＩＤ調節計７及びシーケンサ８が設けられている。
【００１７】
ＲＯ膜分離装置１でのＲＯ膜分離処理においては、原水ＲＯ給水のｐＨによりＲＯ生産水（膜透過水）の水質、例えば電気伝導度が大きく影響を受けるため、給水のｐＨが一定になるように、アルカリ添加手段３又は酸添加手段４により、ＮａＯＨ等のアルカリ又はＨ2ＳＯ4、ＨＣｌ等の酸を添加してｐＨ調整を行う。
【００１８】
例えば、工業用水を凝集、加圧浮上、濾過して得られる水（電気伝導度２００μＳ／ｃｍ）をＲＯ給水とする場合、ｐＨ７に調整してＲＯ膜分離装置１に供給する場合、得られるＲＯ生産水の電気伝導度は５μＳ／ｃｍであり、ｐＨ１０に調整してＲＯ給水とした場合のＲＯ生産水の電気伝導度は２５μＳ／ｃｍである。
【００１９】
従って、ＲＯ生産水の水質の面からはＲＯ給水は、ｐＨ７程度の中性条件とするのが好ましい。
【００２０】
ｐＨ７程度の中性条件で給水を行って運転を行った場合、経時的にＲＯ膜面にスライム等の膜汚染物が付着し、ＲＯ生産水量の低減、差圧の上昇が起こる場合がある。
【００２１】
本発明では、このような膜汚染物による膜性能の低下を防止するために、定期的にＲＯ給水のｐＨを１０〜１２のアルカリ性とする。
【００２２】
このようにＲＯ給水のｐＨを１０〜１２のアルカリ性とすることにより、膜汚染物、特に、スライムや有機物等の膜汚染物を効果的に洗浄除去して膜性能を高めることができる。
【００２３】
このＲＯ給水のｐＨを１０〜１２のアルカリ性に調整する頻度及び期間は、特に３〜１０日に一度の割合で１５〜３００分間とするのが好ましく、このような条件で定期的なｐＨ調整を行うことにより、膜汚染物の蓄積を未然に防止して、アルカリ性のＲＯ給水により効果的に膜汚染物の洗浄除去を行うことができる。
【００２４】
なお、洗浄間隔は短い程、また、洗浄時間は長い程、洗浄効果がある反面、その期間の水質が低下する。従って、洗浄時間は短い程良い。
【００２５】
本実施の形態においては、リモート入力型のＰＩＤ調節計７を用い、例えば１６８時間（１週間）に１回の割合で３時間、ＲＯ給水のｐＨを１０とし、その他はｐＨ７とするように、ＲＯ給水のｐＨ調整条件をプログラミングしたシーケンサ８から制御信号を出力して自動制御にてＲＯ給水のｐＨ調整を行う。
【００２６】
本発明においては、このｐＨ調整期間中も処理水としての膜透過水の取り出しを継続する。
【００２７】
ＲＯ給水のｐＨを１０〜１２のアルカリ性とすると、膜透過水の水質は低下し、例えば電気伝導度は２５μＳ／ｃｍとなるが、本実施の形態では、膜透過水を更にイオン交換装置２でイオン交換処理するため、得られる処理水（イオン交換水）の水質は殆ど影響を受けることはなく、高水質を維持できる（例えば、電気伝導度で０．６６７μＳ／ｃｍ以下）。
【００２８】
なお、アルカリ性のＲＯ給水を行った時の膜透過水もイオン交換装置２に通水することで、イオン交換装置２の負荷が増大し、イオン交換樹脂の再生頻度は若干高くなることが予想されるが、この負荷の増大は一時的なものであるため、再生頻度を大きく悪化させることはない。
【００２９】
なお、このイオン交換装置２としては、混床型又は多床型イオン交換装置（非再生型であっても良い。）等各種のものを用いることができる。また、イオン交換装置に、ＲＯ膜分離装置等の脱塩装置を組み合わせても良い。負荷変動に対応する点からはイオン交換装置が好適である。
【００３０】
このような本発明のＲＯ膜処理方法は、特にスライム等の膜汚染物が付着し易い原水のＲＯ膜分離処理に有効である。
【００３１】
【実施例】
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。
【００３２】
実施例１
図１に示す方法に従って、ＲＯ膜分離処理を行った。原水としては、工業用水の凝集、加圧浮上、濾過処理水を用い、ＲＯ膜分離装置（日東電工（株）製４インチＲＯ膜「ＮＴＲ−７５９ＨＲ」）に運転圧力１６ｋｇ／ｃｍ2、回収率７０％で通水した。
【００３３】
また、混床型イオン交換装置としては、陰イオン交換樹脂（栗田工業（株）製「ＥＸＡＧ」）と陽イオン交換樹脂（栗田工業（株）製「ＥＸＣＧ」）とを２：１で混合したものを用い、ＳＶ＝５０ｈｒ-1で通水した。
【００３４】
ＲＯ給水のｐＨは通常時は７．０の中性条件とし、１６８時間に一回の頻度で３時間、ＲＯ給水のｐＨを１０．０のアルカリ性とし、このアルカリ性にｐＨ調整する間も、採水を行った。
【００３５】
ＲＯ生産水（膜透過水）量（２５℃換算）の経時変化及びこの通水期間中の処理水（膜透過水のイオン交換水）の平均水質（電気伝導度）を調べ、結果を表１に示した。
【００３６】
比較例１
実施例１において、ＲＯ給水のｐＨを常時７．０の一定ｐＨとしたこと以外は同様にして通水を行い、ＲＯ生産水量の経時変化及び処理水の平均水質を調べ、結果を表１に示した。
【００３７】
【表１】
表１より明らかなように、定期的にＲＯ給水をアルカリ性とすることにより、膜性能の低下を防止して、長期に亘り安定な処理を行える。しかも、後段にイオン交換装置を設けることにより、アルカリ性のＲＯ給水を通水することによる処理水の水質低下を防止することができる。
【００３９】
【発明の効果】
以上詳述した通り、本発明のＲＯ膜処理方法によれば、ＲＯ膜分離装置の運転を停止することなく、即ち採水を継続して、ＲＯ膜分離装置の生産水量の低下や差圧上昇の要因となる膜汚染物を効果的に洗浄除去することができる。
【図面の簡単な説明】
【図１】本発明のＲＯ膜処理方法の実施の形態を示す系統図である。
【符号の説明】
１ ＲＯ膜分離装置
２ イオン交換装置
３ アルカリ注入手段
３Ａ アルカリタンク
３Ｂ，４Ｂ 薬注ポンプ
４ 酸注入手段
４Ａ 酸タンク
５ 攪拌機
６ ｐＨ計
７ ＰＩＤ調節計
８ シーケンサ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reverse osmosis membrane (RO membrane) treatment method, and in particular, removes membrane contaminants that cause a decrease in the amount of water produced by the RO membrane separation device and an increase in differential pressure without stopping the operation of the RO membrane separation device. The present invention relates to a RO membrane separation method capable of effectively washing and removing.
[0002]
[Prior art]
In recent years, the RO membrane treatment method has been widely adopted as a desalination method for city water, well water, and the like.
[0003]
In this RO membrane treatment, by continuing the operation of the RO membrane separator, the membrane performance deteriorates due to membrane contaminants attached to and deposited on the RO membrane, and the production water (membrane permeated water) amount decreases and the differential pressure increases. Happens.
[0004]
These membrane contaminants are metal hydroxides such as iron and aluminum, microbial slime, organic substances such as surfactants and polymer flocculants, or scales such as silica and calcium carbonate. RO membranes with reduced slag can recover their performance by cleaning and removing the contaminants with chemical cleaning using chemicals corresponding to the contaminants ("Ultrapure Water Science" Realize, pp. 274-277). page).
[0005]
As this membrane cleaning method, Japanese Patent Application Laid-Open No. 7-16666 describes that a separation membrane such as an RO membrane is alkali cleaned. Japanese Patent Publication No. 52-10785 describes a method of washing and removing membrane contaminants by passing alkaline water having a pH of 9 to 13 through an RO membrane separator for a short time.
[0006]
[Problems to be solved by the invention]
In the conventional membrane cleaning method, the operation of the RO membrane separation device is temporarily stopped, and the cleaning chemical prepared in advance is circulated through the RO membrane separation device in a separate chemical cleaning tank. There are drawbacks that membrane permeate cannot be obtained during operation, the washing operation is complicated, and the apparatus is complicated.
[0007]
In Japanese Patent Publication No. 52-10785, it is described that an alkaline treatment liquid before pH adjustment can be used as cleaning water. However, water sampling operation and cleaning operation are alternately performed, There is a disadvantage that membrane permeate cannot be obtained during the washing operation.
[0008]
The present invention solves the above-mentioned conventional problems and does not stop the operation of the RO membrane separation device, that is, continues the water sampling and causes a membrane that causes a decrease in the amount of produced water and an increase in the differential pressure of the RO membrane separation device. An object of the present invention is to provide an RO membrane treatment method capable of effectively cleaning and removing contaminants.
[0009]
[Means for Solving the Problems]
The RO membrane treatment method of the present invention is a RO membrane treatment method in which raw water is supplied to the RO membrane separator under neutral conditions and membrane permeate is taken out as treated water. RO membrane separation during continuous operation of the RO membrane separator The pH of the raw water supplied to the apparatus is temporarily adjusted to 10 to 12, and the membrane permeated water is taken out as treated water even during the pH adjustment, and the membrane permeated water is subjected to ion exchange treatment with an ion exchange device. It is characterized by.
[0010]
By passing alkaline water having a pH of 10 to 12 through the RO membrane separator, membrane contaminants, particularly membrane contaminants such as slime and organic matter, can be effectively washed away to maintain membrane performance.
[0011]
In the present invention, alkali may be added to the raw water at a certain frequency during the operation of the RO membrane separator to supply water, and a cleaning circulation tank or the like is unnecessary. Moreover, since the membrane permeated water is collected as the treated water even during the pH adjustment, the production water volume can be kept high.
[0012]
In the present invention, the pH adjustment is preferably performed once every 3 to 10 days for 15 to 300 minutes.
[0013]
As described above, the quality of the treated water may be deteriorated by maintaining the water sampling even during pH adjustment. However, an ion exchange device is provided at the rear stage of the RO membrane separation device, and the RO membrane permeated water is ion-exchanged. , Treated water quality can be maintained.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0015]
FIG. 1 is a system diagram showing an embodiment of the RO membrane treatment method of the present invention.
[0016]
This method is applied to an apparatus for treating raw water such as industrial water, city water, well water, and the like by coagulation, pressurized flotation, and filtered water through RO membrane separator 1 and ion exchanger 2 in order. In the raw water supply line, an alkali injection means 3 comprising an alkali tank 3A and a
[0017]
In the RO membrane separation process in the RO membrane separation device 1, the quality of the RO production water (membrane permeated water), for example, the electric conductivity, is greatly affected by the pH of the raw water RO feed water, so that the pH of the feed water is kept constant. Further, the pH is adjusted by adding an alkali such as NaOH or an acid such as H 2 SO 4 or HCl by the alkali addition means 3 or the acid addition means 4.
[0018]
For example, in the case where water (electrical conductivity: 200 μS / cm) obtained by agglomeration, pressure levitation, and filtration of industrial water is used as RO water supply, RO is obtained when adjusted to pH 7 and supplied to the RO membrane separation device 1 The electrical conductivity of the production water is 5 μS / cm, and the electrical conductivity of the RO production water is 25 μS / cm when adjusted to pH 10 and used as RO water supply.
[0019]
Therefore, from the viewpoint of the quality of the RO production water, it is preferable that the RO water supply has a neutral condition of about pH 7.
[0020]
When the operation is performed by supplying water under neutral conditions of about pH 7, membrane contaminants such as slime adhere to the RO membrane surface over time, and the RO production water volume may decrease and the differential pressure may increase.
[0021]
In the present invention, in order to prevent the membrane performance from being deteriorated due to such membrane contaminants, the pH of the RO water supply is periodically made 10 to 12 alkaline.
[0022]
Thus, by making the pH of the RO water supply 10 to 12 alkaline, membrane contaminants, particularly membrane contaminants such as slime and organic matter can be effectively washed and removed to improve membrane performance.
[0023]
The frequency and period for adjusting the pH of the RO water supply to 10 to 12 is preferably 15 to 300 minutes at a rate of once every 3 to 10 days, and regular pH adjustment is performed under such conditions. By doing so, accumulation of membrane contaminants can be prevented in advance, and membrane contaminants can be effectively cleaned and removed by alkaline RO water supply.
[0024]
Note that the shorter the cleaning interval and the longer the cleaning time, the better the cleaning effect, but the water quality during that period decreases. Therefore, a shorter cleaning time is better.
[0025]
In this embodiment, the remote input type PID controller 7 is used, for example, once every 168 hours (one week) for 3 hours, the pH of the RO water supply is set to 10, and the others are set to pH 7. The control signal is output from the
[0026]
In the present invention, the removal of the membrane permeated water as the treated water is continued during this pH adjustment period.
[0027]
If the pH of the RO water supply is 10 to 12 alkaline, the water quality of the membrane permeated water is lowered, for example, the electric conductivity is 25 μS / cm. In this embodiment, the membrane permeated water is further converted by the ion exchange device 2. Since the ion exchange treatment is performed, the water quality of the obtained treated water (ion exchange water) is hardly affected, and a high water quality can be maintained (for example, electric conductivity of 0.667 μS / cm or less).
[0028]
In addition, it is expected that the membrane permeation water when alkaline RO water supply is passed through the ion exchange device 2 will increase the load on the ion exchange device 2 and increase the regeneration frequency of the ion exchange resin slightly. However, since this increase in load is temporary, the reproduction frequency is not greatly deteriorated.
[0029]
In addition, as this ion exchange apparatus 2, various things, such as a mixed bed type or a multi-bed type ion exchange apparatus (it may be a non-regenerative type), can be used. Further, the ion exchange unit may be a combination of the desalination apparatus such as RO membrane separator. An ion exchange apparatus is preferable from the viewpoint of dealing with load fluctuations.
[0030]
Such an RO membrane treatment method of the present invention is particularly effective for RO membrane separation treatment of raw water where membrane contaminants such as slime are likely to adhere.
[0031]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0032]
Example 1
The RO membrane separation treatment was performed according to the method shown in FIG. The raw water used is industrial water agglomeration, pressurized flotation, and filtered water. The RO membrane separator (4-inch RO membrane “NTR-759HR” manufactured by Nitto Denko Corporation) has an operating pressure of 16 kg / cm 2 and a recovery rate. Water was passed at 70%.
[0033]
Moreover, as a mixed bed type ion exchange apparatus, anion exchange resin ("EXAG" manufactured by Kurita Kogyo Co., Ltd.) and cation exchange resin ("EXCG" manufactured by Kurita Kogyo Co., Ltd.) were mixed at a ratio of 2: 1. Water was passed at SV = 50 hr −1 .
[0034]
The pH of the RO feedwater is normally 7.0 under neutral conditions, once every 168 hours for 3 hours, and the pH of the RO feedwater is 10.0 alkalinity. Went water.
[0035]
The time course of the amount of RO product water (membrane permeated water) (25 ° C conversion) and the average water quality (electrical conductivity) of the treated water (ion exchange water of membrane permeated water) during this water flow period were examined. It was shown to.
[0036]
Comparative Example 1
In Example 1, water was passed in the same manner except that the pH of the RO water supply was always set to a constant pH of 7.0, the time-dependent change in the amount of RO production water and the average quality of the treated water were examined, and the results are shown in Table 1. Indicated.
[0037]
[Table 1]
As is clear from Table 1, by periodically making the RO water supply alkaline, it is possible to prevent deterioration in membrane performance and perform stable treatment over a long period of time. In addition, by providing an ion exchange device in the subsequent stage, it is possible to prevent deterioration of the quality of the treated water caused by passing alkaline RO feed water.
[0039]
【The invention's effect】
As described above in detail, according to the RO membrane treatment method of the present invention, without stopping the operation of the RO membrane separation device, that is, continuously collecting water, the RO membrane separation device reduces the production water volume or increases the differential pressure. It is possible to effectively clean and remove film contaminants that cause the above.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a RO membrane treatment method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 RO membrane separator 2 Ion exchange device 3 Alkaline injection means
Claims (2)
逆浸透膜分離装置の連続運転中に逆浸透膜分離装置に供給される原水のｐＨを一時的に１０〜１２とするｐＨ調整を行い、該ｐＨ調整中も膜透過水を処理水として取り出し、該膜透過水をイオン交換装置でイオン交換処理することを特徴とする逆浸透膜処理方法。In the reverse osmosis membrane treatment method, the raw water is supplied to the reverse osmosis membrane separator under neutral conditions, and the membrane permeate is taken out as treated water.
During the continuous operation of the reverse osmosis membrane separator, the pH of the raw water supplied to the reverse osmosis membrane separator is temporarily adjusted to 10 to 12, and the membrane permeate is taken out as treated water during the pH adjustment, A reverse osmosis membrane treatment method comprising subjecting the membrane permeate to ion exchange treatment with an ion exchange device .
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29556597A JP3944973B2 (en) | 1997-10-28 | 1997-10-28 | Reverse osmosis membrane treatment method |
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| Application Number | Priority Date | Filing Date | Title |
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| JP29556597A JP3944973B2 (en) | 1997-10-28 | 1997-10-28 | Reverse osmosis membrane treatment method |
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| JPH11128919A JPH11128919A (en) | 1999-05-18 |
| JP3944973B2 true JP3944973B2 (en) | 2007-07-18 |
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| JP4940631B2 (en) * | 2005-11-07 | 2012-05-30 | 栗田工業株式会社 | Operation method of reverse osmosis membrane separator |
| JP2011115712A (en) * | 2009-12-02 | 2011-06-16 | Mitsubishi Heavy Ind Ltd | Washing method of filter membrane |
| EA201290533A1 (en) * | 2009-12-17 | 2013-01-30 | Винтерсхол Хольдинг Гмбх | METHOD OF OBTAINING HOMOPOLYSACHRIDES |
| JP6049498B2 (en) | 2013-02-25 | 2016-12-21 | 三菱重工業株式会社 | Reverse osmosis membrane device and operating method thereof |
| JP6591205B2 (en) * | 2015-06-02 | 2019-10-16 | 株式会社東芝 | Water treatment system and pH adjustment system |
| JP6973565B1 (en) * | 2020-05-28 | 2021-12-01 | 栗田工業株式会社 | Reverse osmosis membrane treatment method |
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