JP3323812B2 - Method for removing fouling layer formed on film surface - Google Patents
Method for removing fouling layer formed on film surfaceInfo
- Publication number
- JP3323812B2 JP3323812B2 JP20161098A JP20161098A JP3323812B2 JP 3323812 B2 JP3323812 B2 JP 3323812B2 JP 20161098 A JP20161098 A JP 20161098A JP 20161098 A JP20161098 A JP 20161098A JP 3323812 B2 JP3323812 B2 JP 3323812B2
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- JP
- Japan
- Prior art keywords
- membrane
- drying
- layer
- fouling layer
- filtration
- 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.)
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- Separation Using Semi-Permeable Membranes (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、膜ろ過能力の回復
あるいは膜の薬品洗浄の前処理の目的で行われる膜面に
形成されたファウリング層の除去方法に関するものであ
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing a fouling layer formed on a membrane surface for the purpose of restoring membrane filtration ability or pretreatment for chemical cleaning of the membrane.
【０００２】[0002]
【従来の技術】一般に膜によりろ過を継続すると、膜孔
が次第に閉塞したり、膜面上でケーキ層・ゲル層・スケ
ール層が成長し、あるいは微生物自身の増殖・微生物が
産成する代謝物の蓄積による微生物スライム層が形成さ
れ、さらには膜面上の空間がこれらで完全閉塞され、膜
ろ過能力が著しく阻害されることが避けられない。2. Description of the Related Art Generally, when filtration is continued by a membrane, the pores of the membrane gradually close, a cake layer, a gel layer, a scale layer grows on the membrane surface, or the growth of the microorganism itself and metabolites produced by the microorganism. It is inevitable that a microbial slime layer is formed due to the accumulation of water and the space on the membrane surface is completely closed by these, and the membrane filtration ability is significantly impaired.
【０００３】このような原因による膜ろ過能力の低下は
ファウリングと称され、上記のケーキ層・ゲル層・スケ
ール層・微生物スライム層等をファウリング層と総称す
る。このようなファウリング層の形成を抑制したり、膜
面からファウリング層を除去するために、従来から様々
な技術が開発されている。その代表的なものを以下に列
記する。[0003] The decrease in membrane filtration capacity due to such a cause is called fouling, and the above-mentioned cake layer, gel layer, scale layer, microorganism slime layer and the like are collectively referred to as fouling layer. Various techniques have conventionally been developed to suppress the formation of such a fouling layer and to remove the fouling layer from the film surface. The typical ones are listed below.
【０００４】▽クロスフローろ過：膜面上の被ろ過原水
を高流速で流し、その剪断力あるいは掃流効果により、
ケーキ層・ゲル層の堆積を低減する。 ▽逆圧洗浄：膜ろ過水、あるいは高圧空気を膜の二次側
から逆流させて、膜面上のケーキ層・ゲル層を剥離させ
る。 ▽低圧ろ過：膜面にかかる差圧をできるだけ低圧に維持
し、形成したケーキ層・ゲル層の圧密化を最小限にする
ことで、該層の比抵抗の上昇を避け、膜ろ過能力の低下
を防ぐと共に、逆圧洗浄の剥離効果を上げる。 ▽間欠ろ過：ろ過を一時的に停止し、圧密化したケーキ
層・ゲル層を緩和させることにより、比抵抗を回復させ
ると共に、逆圧洗浄の剥離効果を上げる。あるいは、ろ
過停止することで、膜面から被処理原水中への拡散効果
により、ケーキ層・ゲル層を減少させる。 ▽凝集処理：原水中の微細な懸濁粒子あるいは溶解状態
に近いコロイダル粒子などを凝集によりマイクロフロッ
ク化し、膜孔内への侵入を防ぐと共に、堆積ケーキ層の
比抵抗を低値に維持する。また、そのケーキ層の逆圧洗
浄性も良好に維持できる。 ▽薬品注入法：前処理として、塩素・オゾンなどを加
え、その酸化力により被処理原水のろ過性を改善すると
ともに、強力な殺菌効果により、膜面上の微生物スライ
ムの発生を抑制する。また、閉塞あるいはファウリング
したケーキ層・ゲル層の有機物を分解し、ファウリング
進行あるいは比抵抗の上昇を抑制する。 ▽逆洗水への塩素添加：逆圧洗浄を行う洗浄水中に塩素
を添加し、膜の二次側から膜のファウリング物質に塩素
を接触させることにより、膜孔あるいは膜面上のファウ
リング物質の分解〜剥離を促進し、また、塩素の殺菌効
果により微生物スライムの発生も抑制する。 ▽生物分解法：膜面上の一次側空間にて、活性汚泥様の
微生物を高濃度かつ、飢餓状態にさらすことで、膜面上
に形成されるケーキ層・ゲル層あるいは微生物スライム
と言われる微生物体あるいはその代謝物を分解／資化さ
せることにより、膜面上の付着閉塞物の増加を抑制す
る。 ▽空気揺動法：槽浸漬式の外圧中空糸膜において、中空
糸膜外面側を粗大気泡を上昇通過させることで中空糸膜
を揺さぶり、その局所的乱流効果あるいは中空糸膜自身
に微小な降伏強度以内の変形を与えることにより、膜面
上に形成したケーキ層・ゲル層を剥離させる。（セラミ
ック外圧管状膜においては、局所的乱流効果だけであ
る。） ▽スクレーパー方式：堆積したケーキを回転運動等によ
り、膜面に接触しない程度にスクレーパーでケーキ層を
直接削り取る方法。スクレーパーが膜に接すると、膜面
に損傷を与えるため、あまり薄くは削り取ることはでき
ない。 ▽膜振動法：膜自身に往復あるいは回転往復振動を与
え、膜面上の物質移動係数を高い状態に維持すること
で、膜面上のケーキ層・ゲル層の形成を防ぐ。 ▽スポンジ・ボール洗浄：内圧管状膜では、その内径に
略等しいスポンジ状の略球状物をクロスフローさせる原
水中に定期的に同伴させることで、膜面を擦過し、形成
するケーキ層・ゲル層を削り取る。[0004] Cross-flow filtration: The raw water to be filtered on the membrane surface is flowed at a high flow rate, and the shear force or the sweeping effect causes the raw water to be filtered.
Reduce the accumulation of cake and gel layers. ▽ Back pressure washing: The cake layer / gel layer on the membrane surface is peeled off by backflowing membrane filtered water or high pressure air from the secondary side of the membrane. ▽ Low pressure filtration: By keeping the differential pressure applied to the membrane surface as low as possible and minimizing the compaction of the formed cake layer and gel layer, avoiding an increase in the specific resistance of the layer and lowering the membrane filtration capacity. As well as increase the peeling effect of back pressure cleaning. (4) Intermittent filtration: The filtration is temporarily stopped to relax the compacted cake layer and gel layer, thereby restoring the specific resistance and increasing the peeling effect of back pressure washing. Alternatively, by stopping the filtration, the cake layer / gel layer is reduced by the diffusion effect from the membrane surface into the raw water to be treated. ▽ Agglomeration treatment: Micro-flocculates fine suspended particles or colloidal particles that are almost dissolved in raw water by agglomeration to prevent intrusion into the pores of the membrane and to keep the specific resistance of the deposited cake layer at a low value. In addition, the backwashing property of the cake layer can be well maintained. (4) Chemical injection method: As a pretreatment, chlorine and ozone are added to improve the filterability of raw water to be treated by the oxidizing power, and the generation of microbial slime on the membrane surface is suppressed by a strong sterilizing effect. Further, it decomposes organic substances in the clogged or fouled cake layer / gel layer to suppress the progress of fouling or increase in specific resistance.塩 素 Addition of chlorine to backwashing water: Chlorine is added to washing water for backpressure washing, and chlorine is brought into contact with the fouling substance of the membrane from the secondary side of the membrane, thereby fouling on the membrane hole or membrane surface. It promotes the decomposition and delamination of substances and also suppresses the generation of microbial slime due to the bactericidal effect of chlorine. ▽ Biodegradation method: A cake layer / gel layer or microbial slime formed on the membrane surface by exposing activated sludge-like microorganisms to high concentration and starvation in the primary space on the membrane surface By decomposing / assembling the microorganisms or metabolites thereof, the increase in the amount of adhered blockage on the membrane surface is suppressed. ▽ Air swinging method: In a tank immersion type external pressure hollow fiber membrane, coarse bubbles rise and pass through the outer surface side of the hollow fiber membrane to shake the hollow fiber membrane, and the local turbulence effect or the minuteness of the hollow fiber membrane itself By giving a deformation within the yield strength, the cake layer and the gel layer formed on the film surface are peeled off. (In the case of a ceramic external pressure tubular membrane, there is only a local turbulence effect.) ▽ Scraper method: A method in which the deposited cake is directly scraped with a scraper by a rotary motion or the like so as not to contact the membrane surface. When the scraper comes into contact with the membrane, it damages the membrane surface, so it cannot be scraped off too thin. (4) Membrane vibration method: A film layer or a gel layer is prevented from being formed on a film surface by applying reciprocating or rotating reciprocating vibration to the film itself and maintaining a high mass transfer coefficient on the film surface.洗浄 Sponge ball cleaning: In the case of an internal pressure tubular membrane, a sponge-like sphere having approximately the same inner diameter is periodically entrained in raw water for cross-flow, thereby rubbing the membrane surface and forming a cake layer / gel layer. Scrape off.
【０００５】実用的には、上記した各種の技術を組み合
わせてファウリング層による膜のろ過能力の低下を抑制
しつつ運転がなされているが、どの方法を採用しても中
長期的には、膜のファウリングに伴うろ過能力の低下を
避けることはできない。また実用範囲においては、膜ろ
過流束を高める程、膜のファウリング速度が上昇するこ
とが知られている。従って膜のファウリングを防止する
ためには膜ろ過流束は小さい方が好ましいのであるが、
膜を経済的に使用するには、設備費、運転費、設備設置
面積のいずれの面でも、膜ろ過流束を高くすれば良いこ
とは自明である。その結果、実用的には膜ろ過流束をあ
る程度低めに設定して薬品洗浄頻度を抑制しつつ、閉塞
が進行した膜は薬品洗浄によりファウリング層を分解・
除去する方法を取らざるを得ないのが実情である。[0005] In practice, the above-described various techniques are combined to operate while suppressing a decrease in the filtration capacity of the membrane due to the fouling layer. It is impossible to avoid a decrease in filtration capacity due to fouling of the membrane. It is also known that within the practical range, the higher the membrane filtration flux, the higher the fouling speed of the membrane. Therefore, in order to prevent membrane fouling, it is preferable that the membrane filtration flux is small,
It is obvious that in order to use the membrane economically, it is only necessary to increase the membrane filtration flux in terms of equipment cost, operation cost, and equipment installation area. As a result, in practice, the membrane filtration flux is set to a somewhat lower level to suppress the frequency of chemical cleaning, while the membrane that has been clogged decomposes the fouling layer by chemical cleaning.
In fact, it is necessary to take a method of removal.
【０００６】しかし、この薬品洗浄も次のような多くの
実用化上の障害を持つ。 ▽薬品洗浄の間、ろ過停止となるため補完の措置が必要
となる。 ▽薬品洗浄の実施時期判断に技術性が必要。判断を誤る
と、膜が劣化したり、薬品洗浄による回復可能範囲を超
え、膜交換が必要となる。 ▽薬品洗浄に用いる薬種選定、濃度選定、多段洗浄の組
合せ選定に技術性が必要。 ▽多量の薬液が必要。さらに多量の洗浄廃液が発生し、
結果として産業廃棄物が生ずる。 ▽膜装置の残留薬液を洗い流すのに、薬液容積の何倍も
の、洗浄水が必要となり、これ自身が産業廃棄物とな
り、あるいは除害処分が必要となる場合がある。 ▽薬液が残留していると、運転再開後の膜ろ過水に混入
し、多くの場合、問題が生ずる。従って、運転復帰の
際、残留確認を確実に行うことが必要となる。 ▽薬品洗浄の頻度、薬液濃度、薬種は、膜装置内の接液
部に腐食・溶解などの悪影響を与え、機器類寿命を短縮
したり、設備製作費の上昇をもたらす。[0006] However, this chemical cleaning also has many practical obstacles as follows. (4) During chemical cleaning, filtration will be stopped, and additional measures will be required.技術 Technology is required to judge when to perform chemical cleaning. If the determination is wrong, the membrane will be deteriorated or will exceed the recoverable range by chemical cleaning, and the membrane will need to be replaced.技術 Technology is required for selection of chemical species, concentration, and multi-stage cleaning used for chemical cleaning. ▽ A large amount of chemical is required. A larger amount of washing waste liquid is generated,
The result is industrial waste.洗 い Washing water, which is many times the volume of the chemical solution, is required to wash away the chemical solution remaining in the membrane device, which may itself become industrial waste or require detoxification. ▽ If the chemical solution remains, it will be mixed into the membrane filtered water after the restart of operation, and in many cases, a problem will occur. Therefore, when returning to operation, it is necessary to surely confirm the residue.頻 度 The frequency of chemical cleaning, chemical concentration, and chemical type have adverse effects such as corrosion and dissolution on liquid contact parts in the membrane device, shortening the life of equipment and increasing equipment manufacturing costs.
【０００７】[0007]
【発明が解決しようとする課題】本発明は上記した従来
の問題点を解決し、膜面に形成されたファウリング層
を、薬液に頼ることなく確実に除去することができる方
法を提供することである。しかし本発明は必ずしも薬品
洗浄を排除するものではなく、薬品洗浄の前処理として
実施することにより、薬品洗浄の負荷を軽減することも
可能である。SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a method for reliably removing a fouling layer formed on a film surface without relying on a chemical solution. It is. However, the present invention does not necessarily exclude chemical cleaning, and it is also possible to reduce the load of chemical cleaning by performing it as a pretreatment for chemical cleaning.
【０００８】[0008]
【課題を解決するための手段】上記の課題を解決するた
めになされた請求項１の発明は、膜ろ過により膜面に形
成されたファウリング層を、乾燥させることにより収縮
させて膜面から剥離させることを特徴とするものであ
る。また、請求項２の発明は、薬品洗浄の前処理とし
て、膜ろ過により膜面に形成されたファウリング層を乾
燥させることにより収縮させ、膜面から剥離させること
を特徴とするものである。いずれの発明においても、乾
燥・収縮させたファウリング層を、ガス体あるいは液体
により膜面から剥離させるようにしてもよい。このファ
ウリング層の乾燥は、膜の一次側への通気により行わせ
ることができ、対象となる膜面は、ケーシング収納型の
膜エレメントあるいは槽浸漬の膜エレメントの膜面のい
ずれでもよい。Means for Solving the Problems According to the first aspect of the present invention, which has been made to solve the above-mentioned problems, a fouling layer formed on a membrane surface by membrane filtration is shrunk by drying to shrink the fouling layer from the membrane surface. It is characterized by peeling. Further, the invention of claim 2 is characterized in that as a pretreatment for chemical cleaning, the fouling layer formed on the membrane surface by membrane filtration is shrunk by drying and peeled off from the membrane surface. In any of the inventions, the dried and shrunk fouling layer may be separated from the film surface by a gas or a liquid. The drying of the fouling layer can be performed by ventilating the primary side of the membrane, and the target membrane surface may be any of a casing storage type membrane element and a membrane element of a tank element immersed in a bath.
【０００９】このように、本発明は膜孔や膜面上に付着
したケーキ層・ゲル層等が成長した段階あるいは薬品洗
浄の前処理段階で、この付着閉塞層であるファウリング
層を乾燥させることにより収縮させ、膜面からの剥離除
去を行うものであり、この際に膜孔に入り込んで膜孔を
閉塞しているファウリング層も除去することができる。
従来はろ過膜の表面を乾燥させることは膜の性状を変化
させるおそれがあるために避けるべきこととされてお
り、本発明はこの従来の常識を覆してなされたものであ
る。As described above, according to the present invention, the fouling layer, which is the adhesion blocking layer, is dried at the stage of growing the cake layer, the gel layer, etc. adhering to the membrane pores and the membrane surface or at the pretreatment stage of chemical cleaning. By doing so, the film is shrunk and peeled off from the film surface. At this time, the fouling layer that enters the film hole and closes the film hole can also be removed.
Conventionally, drying the surface of a filtration membrane has been considered to be avoided because of the possibility of changing the properties of the membrane, and the present invention has been made to reverse this conventional wisdom.
【００１０】本発明者の観察によれば、膜のろ過能力を
低下させるケーキ層・ゲル層等の固形物濃度は概ね0.1
〜20％の範囲にあり、特殊な性状の濃縮物質を除き、乾
燥される過程で収縮が伴う。これは、水分が80〜99．9
％の範囲で固形物の間に介在していたり、例えば蛋白質
のような有機物質であれば、自由水分・付着水分などの
形態で固形物の隙間空間に保持されていたり、原子・分
子レベルで物理的・化学的吸着した状態で存在してお
り、これらの水分子が乾燥により固形物から抜け出す際
に、固形物自身に収縮を引き起し、外見的に観察される
収縮を引き起こすためである。According to observations made by the present inventor, the concentration of solids in the cake layer, gel layer, etc., which reduces the filtration capacity of the membrane, is approximately 0.1%.
It is in the range of ~ 20%, and shrinks during drying process except for concentrated substances of special properties. It has a water content of 80-99.9.
%, It is interposed between solids, for example, if it is an organic substance such as protein, it is held in the interstitial space of the solid in the form of free moisture or attached moisture, or at the atomic or molecular level. It is present in a physically and chemically adsorbed state, and when these water molecules escape from the solid by drying, they cause the solid itself to contract, causing the apparently observed contraction .
【００１１】本発明により膜面上のケーキ層・ゲル層等
のファウリング層を乾燥させれば、例えば、膜面上に堆
積したケーキ層・ゲル層と膜面の接触面では、ケーキ層
・ゲル層の乾燥収縮に膜面が追従できなくなり、剥離が
生じる。また、膜表面に近い膜孔内に侵入し、閉塞した
目詰まり物質があれば、乾燥により著しい容積減少、す
なわちサイズ減少が生じるため、膜孔から系外への脱落
が容易となる。この結果、ファウリング層が除去されて
膜のろ過能力が回復し、薬品洗浄が不要となったり、仮
に薬品洗浄が必要であってもその負担を大幅に軽減させ
ることが可能となる。When the fouling layer such as the cake layer / gel layer on the film surface is dried according to the present invention, for example, the cake layer / gel layer deposited on the film surface and the contact surface between the film surface and the cake layer / gel layer are dried. The film surface cannot follow the drying shrinkage of the gel layer, and peeling occurs. In addition, if there is a clogging substance that has penetrated into the pores near the membrane surface and clogged, drying significantly reduces the volume, that is, reduces the size, so that the pores can easily fall out of the membrane. As a result, the fouling layer is removed, the filtration ability of the membrane is restored, and chemical cleaning becomes unnecessary. Even if chemical cleaning is required, the burden can be greatly reduced.
【００１２】本発明は、精密ろ過膜及び限外ろ過膜（孔
径0.003 〜10μm)に対して特に有効である。また本発明
は、モノリス型の膜のほかに、内圧・外圧中空糸膜、内
圧・外圧管状膜、平膜（回転型、袋型、積層型）にも適
用することができる。モジュール形態は、ケーシング収
納型のほかに槽浸漬型であってもよい。ファウリング層
の乾燥とともに膜自体でも乾燥が進むため、本発明が適
用できる膜は、アルミナ、チタニア、ジルコニア等のセ
ラミック膜のほか、ガラス系、金属系の膜や、テフロン
等の耐乾燥性を有する高分子系の材料よりなる膜であ
る。The present invention is particularly effective for microfiltration membranes and ultrafiltration membranes (pore diameter 0.003 to 10 μm). In addition to the monolith type membrane, the present invention can be applied to an internal / external pressure hollow fiber membrane, an internal / external pressure tubular membrane, and a flat membrane (rotary type, bag type, laminated type). The module form may be a tank immersion type in addition to the casing storage type. Since drying proceeds with the film itself as the fouling layer is dried, the film to which the present invention can be applied is not limited to ceramic films such as alumina, titania, and zirconia, as well as glass-based and metal-based films, and has a high drying resistance such as Teflon. It is a film made of a polymer-based material.
【００１３】乾燥を実施すべき時期は、目的により異な
る。即ち、膜ろ過能力の回復を目的とする請求項１の発
明の場合には、ろ過期間中に膜のファウリングにより差
圧が上昇した時あるいはろ過流量が低下した時に行えば
よく、薬品洗浄の負担軽減を目的とする請求項２の発明
の場合には、薬品洗浄の前に行えばよい。The time at which drying is to be performed depends on the purpose. In other words, in the case of the invention of claim 1 for the purpose of restoring the membrane filtration ability, it may be performed when the differential pressure increases due to fouling of the membrane during the filtration period or when the filtration flow rate decreases, and chemical cleaning is performed. In the case of the invention of claim 2 for the purpose of reducing the burden, it may be performed before the chemical cleaning.
【００１４】乾燥に先立ち、膜の一次側及び二次側の保
有水を排出することが好ましい。モノリス膜の場合に
は、一次側と二次側の保有水を排出後に二次側から空気
圧を加え、膜エレメント内部の保有水を膜面へ押し出す
ことが好ましい。槽浸漬型の膜は槽内を排水するか、膜
を槽外に搬出することが必要である。Prior to drying, it is preferred to drain the water retained on the primary and secondary sides of the membrane. In the case of a monolithic membrane, it is preferable to push air pressure from the secondary side after discharging the water retained on the primary side and the secondary side to push out the water retained inside the membrane element to the membrane surface. It is necessary to drain the inside of the tank or carry the membrane out of the tank.
【００１５】乾燥は好ましくは一次側への通気乾燥によ
り行う。しかし膜の材質、形状、形態や設置条件によっ
ては自然乾燥を行ってもよい。通気乾燥の場合には、0
〜60℃の空気を用いることが好ましい。温度が0 ℃以下
では水分が凍結してファウリング層の剥離が妨げられ、
60℃以上ではファウリング層の剥離性が低下したり、発
火・燃焼等により乾燥物の変成が生ずるので好ましくな
い。通気手段は一般的には送風機であるが、ブロワや空
気槽に蓄圧された圧縮空気であってもよい。加温のた
め、ヒーターや熱交換器を併用してもよい。乾燥を促進
するために、通気される空気の相対湿度は70％以下とし
ておくことが好ましい。除湿器による除湿を併用するこ
とも効果的である。[0015] Drying is preferably carried out by air drying on the primary side. However, natural drying may be performed depending on the material, shape, form, and installation conditions of the film. 0 for through drying
It is preferred to use air at 6060 ° C. At a temperature of 0 ° C. or lower, the moisture freezes and hinders the fouling layer from peeling off.
A temperature of 60 ° C. or higher is not preferable because the fouling layer peels off poorly and the dry matter is denatured by ignition or combustion. The ventilation means is generally a blower, but may be compressed air stored in a blower or an air tank. For heating, a heater or a heat exchanger may be used in combination. In order to promote drying, the relative humidity of the ventilated air is preferably set to 70% or less. It is also effective to use a dehumidifier together.
【００１６】[0016]
【発明の実施の形態】以下に本発明の好ましい実施形態
を示す。図１は、モノリス型のセラミック膜エレメント
１をケーシング２に収納したケーシング収納型の膜モジ
ュールを示す。この膜エレメントは鉛直に設置され、例
えば一次側の原水供給口３から原水を供給し、膜ろ過水
を二次側の膜ろ過水取り出し口４から取り出すデッドエ
ンドろ過法で運転される。ろ過の継続により膜表面にフ
ァウリング層が形成された際、次の手順によりファウリ
ング層を膜面から剥離させる。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. FIG. 1 shows a casing storage type membrane module in which a monolithic ceramic membrane element 1 is stored in a casing 2. This membrane element is installed vertically, and is operated, for example, by a dead end filtration method in which raw water is supplied from a raw water supply port 3 on a primary side and membrane filtered water is removed from a membrane filtered water outlet 4 on a secondary side. When the fouling layer is formed on the membrane surface by the continuation of the filtration, the fouling layer is separated from the membrane surface by the following procedure.
【００１７】まず、原水および膜ろ過水をケーシング２
の内部から排出した後、二次側の膜ろ過水取り出し口４
から加圧空気を導入してモノリス型のセラミック膜エレ
メント１の保有水を膜面まで押し出す。次に図２のよう
に、ケーシング２の上部の開口５から送風機により乾燥
用の空気を下向きに通気し、セラミック膜エレメント１
を一次側から乾燥させる。その結果、膜表面に付着して
いるファウリング層は乾燥し収縮するが、セラミック膜
エレメント１自体は収縮しないために、ファウリング層
の剥離が始まる。乾燥の初期には、乾燥用空気の出口温
度は入口温度に比べて低いが、乾燥の進行に伴って出口
温度は上昇し、入口温度と略同温となったときに乾燥を
終了する。First, raw water and membrane filtered water are supplied to a casing 2.
After being discharged from the inside of the membrane, the secondary side membrane filtration water outlet 4
, Pressurized air is introduced to push out the water retained in the monolithic ceramic membrane element 1 to the membrane surface. Next, as shown in FIG. 2, air for drying is blown downward from an opening 5 in an upper portion of the casing 2 by a blower, and the ceramic membrane element 1 is opened.
Is dried from the primary side. As a result, the fouling layer adhering to the membrane surface dries and shrinks, but the ceramic membrane element 1 itself does not shrink, so that the fouling layer starts to peel off. At the beginning of drying, the outlet temperature of the drying air is lower than the inlet temperature, but the outlet temperature rises with the progress of drying, and the drying ends when the temperature becomes substantially the same as the inlet temperature.
【００１８】なお、この実施形態において乾燥用空気を
下向きに通気したのは、下向流の方が剥離した乾燥物が
空気流に乗って排出され易いことと、乾燥に伴う冷却に
より空気の密度が増加すること、上記したようなデッド
エンドろ過の場合には上部のケーキ層がより厚くなる場
合が多いため、上方から乾燥用空気を流すことにより乾
燥効率を上げることができるためである。In this embodiment, the drying air is ventilated downward because the dried product separated in the downward flow is more likely to be discharged along with the air flow, and the density of the air is reduced by cooling accompanying drying. This is because, in the case of dead-end filtration as described above, the upper cake layer is often thicker, so that drying efficiency can be increased by flowing drying air from above.
【００１９】乾燥終了後、乾燥物をケーシング２内から
確実に排除するために、空気又は水を用いることができ
る。空気を用いる場合には、乾燥終了後に二次側から加
圧空気を流して剥離を促進したうえ、一次側上部から低
圧空気で下向きのブローを行い、乾燥物を下方に排出さ
せる。水を用いる場合には、二次側から膜ろ過水などの
清澄な水を導入して膜内を逆流させ、膜内部の乾燥収縮
物を押し出しつつ、膜面から剥離しかけた乾燥収縮物を
洗い流す。その後、一次側上部から加圧空気を導入し、
一次側に保持された上記の逆流水を下方に押し出し、ケ
ーシング２の内部から排出させればよい。次に、本発明
の効果を実施例により確認した結果を示す。After the drying is completed, air or water can be used to surely remove the dried material from the casing 2. When air is used, after the drying is completed, pressurized air is flowed from the secondary side to promote the separation, and then the blown air is blown downward with low-pressure air from the upper part of the primary side to discharge the dried material downward. When water is used, clear water such as membrane filtered water is introduced from the secondary side to reverse the inside of the membrane, and while extruding dry shrinkage inside the membrane, washing away the dry shrinkage that has come off from the membrane surface . After that, pressurized air is introduced from the upper part of the primary side,
What is necessary is just to push the above-mentioned backflow water held on the primary side downward, and to discharge it from the inside of the casing 2. Next, the results of confirming the effects of the present invention by examples will be described.
【００２０】[0020]
【実施例】アルミナ製のセラミック膜エレメント（外径
30mm、流路内径2.5mm 、流路数61、膜面積0.48m2、膜孔
径0.1 μm のモノリス膜) を用い、流束1.2m／日のろ過
条件で連続運転を行った。原水には山間の河川表流水を
用い、ポリ塩化アルミニウムによる凝集操作を前処理と
して行った。運転期間中、６時間毎に逆洗を行っていた
が、膜の表面に通常の逆洗操作では除去できないファウ
リング層が次第に形成され、ろ過能力が低下した。顕微
鏡観察によるファウリング層の厚みはおよそ0.3 〜0.5m
m で、膜面のほとんどの部分が覆われていた。DESCRIPTION OF THE PREFERRED EMBODIMENTS Alumina ceramic membrane element (outer diameter
A continuous operation was performed under a filtration condition of 1.2 m / day using a monolith membrane having a diameter of 30 mm, a flow path inner diameter of 2.5 mm, a flow path number of 61, a membrane area of 0.48 m 2 , and a membrane pore diameter of 0.1 μm). Surface water from mountainous rivers was used as raw water, and coagulation operation with polyaluminum chloride was performed as pretreatment. During the operation, backwashing was performed every 6 hours. However, a fouling layer that could not be removed by a normal backwashing operation was gradually formed on the surface of the membrane, and the filtration capacity was reduced. The thickness of the fouling layer by microscopic observation is about 0.3 to 0.5 m
m covered most of the membrane surface.
【００２１】このようにファウリングした膜エレメント
２本を用い、まず乾燥前の純水補正流束を測定した。次
に温度49℃、相対湿度21％の空気を65L/分の流量で膜の
一次側に上から下に流し、ファウリング層を乾燥させ
た。乾燥中は出口空気温度、出口空気湿度、膜重量を記
録し、これらの値の変化が少なくなったところで乾燥を
終了した。終了時の出口空気温度は39℃、相対湿度は31
％であった。なお、１本（ＲＵＮ１）は純水フラックス
を測定してから一次側と二次側の保有水を排出した後に
上記の乾燥を行い、他の１本（ＲＵＮ２）はＲＵＮ１と
同様な保有水排出の後、さらに二次側に3kgf/cm2の圧力
で空気を加え、膜の多孔質部分の水分を押出してから上
記の乾燥を行った。Using the two membrane elements thus fouled, first, the corrected pure water flux before drying was measured. Next, air having a temperature of 49 ° C. and a relative humidity of 21% was flowed from the top to the bottom of the membrane at a flow rate of 65 L / min to dry the fouling layer. During the drying, the outlet air temperature, the outlet air humidity, and the film weight were recorded, and when the change in these values became small, the drying was terminated. Exit air temperature at the end of 39 ° C, relative humidity 31
%Met. One (RUN1) measures the pure water flux and then discharges the water retained on the primary and secondary sides, and then performs the drying described above. The other (RUN2) discharges the same retained water as RUN1. Thereafter, air was further applied to the secondary side at a pressure of 3 kgf / cm 2 to extrude moisture from the porous portion of the membrane, and then the above-mentioned drying was performed.
【００２２】乾燥が終了した膜に、エア逆洗（二次側か
ら一次側へ2kgf/cm2の圧力で５秒間通気）及びエアブロ
ー（一次側の上から下向きに2kgf/cm2の圧力で５秒間通
気）を行い、さらに水による逆洗（4kgf/cm2の圧力で３
秒通水）とブロー（1.5kgf/cm2の圧力で３秒間通気）を
行った。The dried membrane is subjected to air backwashing (ventilation from the secondary side to the primary side at a pressure of 2 kgf / cm 2 for 5 seconds) and air blowing (primary side downward from the top at a pressure of 2 kgf / cm 2 at a pressure of 2 kgf / cm 2 ). For 2 seconds and backwash with water (3 kgf / cm 2 at 3 kgf / cm 2 ).
For 2 seconds) and blowing (aeration at a pressure of 1.5 kgf / cm 2 for 3 seconds).
【００２３】膜の補正流束は、ＲＵＮ１では乾燥前は0.
36m/日であったが乾燥後は11.99m/ 日となり、ＲＵＮ２
では乾燥前は0.73m/日であったが乾燥後は12.89m/ 日と
なった。なお、使用した膜の初期補正流束は20m/日であ
り、いずれのサンプルも初期の６割まで回復した。ここ
で補正流束とは、膜ろ過流束を水温25℃、膜差圧98.1kP
a の条件に換算した値を意味する。The corrected flux of the membrane is RUN 1 before drying.
It was 36m / day, but after drying it was 11.99m / day.
Before drying, it was 0.73 m / day, but after drying it was 12.89 m / day. The initial correction flux of the membrane used was 20 m / day, and all samples recovered to 60% of the initial value. Here, the correction flux refers to the membrane filtration flux at a water temperature of 25 ° C and a membrane pressure difference of 98.1 kP.
It means the value converted to the condition of a.
【００２４】膜ろ過では、膜差圧＝流束×透過抵抗と表
すこともでき、透過抵抗＝膜差圧／流束の右辺は補正流
束の逆数となる。上記のＲＵＮ１における補正流束を透
過抵抗で評価すると、初期補正流束の20m/日に対応する
膜自身の透過抵抗は0.05、乾燥前の補正流束0.36m/日は
2.78、乾燥後の補正流束12.89m/ 日は0.08である。従っ
て、ファウリング層による閉塞抵抗は乾燥前は2.78-0.0
5 ＝2.73であったのが、乾燥後は0.08-0.05 ＝0.03にま
で減少したこととなり、ファウリング層による閉塞抵抗
は約99％まで回復したこととなる。In the membrane filtration, the differential pressure of the membrane = flux × permeation resistance can also be expressed, and the right side of the permeation resistance = membrane differential pressure / flux is the reciprocal of the correction flux. When the corrected flux in the above-mentioned RUN1 is evaluated by permeation resistance, the permeation resistance of the membrane itself corresponding to 20 m / day of the initial corrected flux is 0.05, and the corrected flux before drying is 0.36 m / day.
2.78, the corrected flux 12.89m / day after drying is 0.08. Therefore, the blocking resistance due to the fouling layer is 2.78-0.0 before drying.
5 = 2.73, but after drying, it decreased to 0.08-0.05 = 0.03, which means that the resistance to closure by the fouling layer was restored to about 99%.
【００２５】[0025]
【発明の効果】以上に説明したように、本発明によれば
薬品洗浄によらずファウリング層を確実に除去すること
ができる。このため、本発明を膜ろ過性能の回復の目的
で実施すれば、次のような多くの効果を得ることができ
る。 維持管理上、困難が伴う薬品洗浄の回数を削減でき
る。 薬品廃液の処理処分量を低減できる。 薬品洗浄の発生頻度を考慮する必要性が低下するた
め、膜ろ過流束の設計値を高くできる。 これにより、膜設備建設費、膜交換費が主体となる
維持管理費を大幅に低減することができる。As described above, according to the present invention, the fouling layer can be reliably removed without using chemical cleaning. Therefore, if the present invention is implemented for the purpose of restoring the membrane filtration performance, the following many effects can be obtained. The number of times of chemical cleaning, which is difficult to maintain, can be reduced. The amount of treatment and disposal of chemical waste liquid can be reduced. Since the necessity of considering the frequency of occurrence of chemical cleaning is reduced, the design value of the membrane filtration flux can be increased. As a result, it is possible to drastically reduce the maintenance and management cost mainly including the membrane facility construction cost and the membrane replacement cost.
【００２６】また、本発明を薬品洗浄の前処理の目的で
実施すれば、次のような多くの効果を得ることができ
る。 薬品洗浄の負担が軽減されるため、薬液濃度の低
減、薬品洗浄時間の短縮、薬品使用量の減少を図ること
ができる。 廃液濃度も低下するため、その処理処分が容易とな
る。 操作の安全性が高まり、接液部の腐食等の劣化も低
下するため、装置材料費も低減できる。 洗浄液の変成（濃度低下、汚濁）が少ないため、薬
液の再利用が可能となる。 例えば次亜塩素酸ナトリウム水溶液を洗浄液として
使用する場合にも、毒性・発症性の高い副生成物の発生
が抑制できる。 洗浄液濃度が低いため、残留薬液を洗い流す洗浄水
量が削減でき、その洗浄時間も短縮できる。Further, if the present invention is carried out for the purpose of pretreatment for chemical cleaning, the following many effects can be obtained. Since the burden of chemical cleaning is reduced, it is possible to reduce the chemical solution concentration, shorten the chemical cleaning time, and reduce the amount of chemical used. Since the concentration of the waste liquid also decreases, the treatment and disposal thereof become easy. Since the safety of operation is enhanced and the deterioration such as corrosion of the liquid contact part is reduced, the material cost of the apparatus can be reduced. Since there is little denaturation (concentration reduction, contamination) of the cleaning solution, the chemical solution can be reused. For example, even when an aqueous solution of sodium hypochlorite is used as a cleaning solution, generation of by-products having high toxicity and onset can be suppressed. Since the concentration of the washing solution is low, the amount of washing water for washing away the residual chemical solution can be reduced, and the washing time can be shortened.
【図１】本発明の実施形態を示す断面図である。FIG. 1 is a sectional view showing an embodiment of the present invention.
【図２】本発明の乾燥工程を示す断面図である。FIG. 2 is a cross-sectional view illustrating a drying step of the present invention.
１ セラミック膜エレメント、２ ケーシング、３ 一
次側の原水供給口、４二次側の膜ろ過水取り出し口、５
上部の開口1 ceramic membrane element, 2 casing, 3 primary side raw water supply port, 4 secondary side membrane filtered water outlet, 5
Upper opening
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平７−251041（ＪＰ，Ａ) 特開 平５−220499（ＪＰ，Ａ) 特開 平８−39062（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) B01D 65/02 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-251041 (JP, A) JP-A-5-220499 (JP, A) JP-A 8-39062 (JP, A) (58) Field (Int.Cl. 7 , DB name) B01D 65/02
Claims (5)
グ層を、乾燥させることにより収縮させ、膜面から剥離
させることを特徴とする膜面に形成されたファウリング
層の除去方法。1. A method for removing a fouling layer formed on a membrane surface, wherein the fouling layer formed on the membrane surface by membrane filtration is shrunk by drying and peeled off from the membrane surface.
面に形成されたファウリング層を乾燥させることにより
収縮させ、膜面から剥離させることを特徴とする膜面に
形成されたファウリング層の除去方法。2. A pretreatment for chemical cleaning, wherein a fouling layer formed on a membrane surface by membrane filtration is shrunk by drying and peeled off from the membrane surface. How to remove layers.
体あるいは液体により膜面から剥離させる請求項１又は
２に記載の膜面に形成されたファウリング層の除去方
法。3. The method for removing a fouling layer formed on a film surface according to claim 1, wherein the dried and shrunk fouling layer is separated from the film surface by a gas or a liquid.
より乾燥させる請求項１〜３の何れかに記載の膜面に形
成されたファウリング層の除去方法。4. The method for removing a fouling layer formed on a film surface according to claim 1, wherein the fouling layer is dried by ventilation to the primary side of the film.
あるいは槽浸漬の膜エレメントの膜面である請求項１〜
４の何れかに記載の膜面に形成されたファウリング層の
除去方法。5. The membrane surface of a membrane element of a casing storage type or a membrane element immersed in a bath.
5. The method for removing a fouling layer formed on a film surface according to any one of 4.
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|---|---|---|---|
| JP20161098A JP3323812B2 (en) | 1998-07-16 | 1998-07-16 | Method for removing fouling layer formed on film surface |
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| JP4714367B2 (en) * | 2001-05-16 | 2011-06-29 | メタウォーター株式会社 | Membrane filtration method |
| JP3931315B2 (en) * | 2003-02-17 | 2007-06-13 | 東レ・メディカル株式会社 | Dialysis therapy dial holder |
| EP1745837B1 (en) | 2004-05-13 | 2014-07-09 | Metawater Co., Ltd. | Back washing method of filtration membrane |
| US7677399B2 (en) | 2006-12-25 | 2010-03-16 | Ngk Insulators, Ltd. | Separation membrane and manufacturing process thereof |
| US20100084338A1 (en) * | 2007-03-22 | 2010-04-08 | Metawater Co., Ltd. | Method and apparatus for treating ballast water |
| JP6405596B2 (en) * | 2015-11-18 | 2018-10-17 | 三菱重工環境・化学エンジニアリング株式会社 | Membrane module and water treatment system |
| JP2017104832A (en) * | 2015-12-11 | 2017-06-15 | 三菱重工環境・化学エンジニアリング株式会社 | Membrane separator |
| CN105435529B (en) * | 2015-12-31 | 2017-10-17 | 湖州富优得膜分离科技有限公司 | Aeration embrane method water treatment facilities in a kind of |
| WO2019025242A1 (en) * | 2017-08-03 | 2019-02-07 | Basf Se | Process for cleaning a membrane comprising drying the membrane |
| JP2020040050A (en) * | 2018-09-13 | 2020-03-19 | オルガノ株式会社 | Membrane filtration method and membrane filtration apparatus |
| CN113274881A (en) * | 2021-06-29 | 2021-08-20 | 迈海(苏州)环保科技有限公司 | Flexible tubular large-aperture membrane filter device and cleaning method thereof |
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| JP4555432B2 (en) * | 2000-04-13 | 2010-09-29 | 株式会社ダイゾー | Aerosol products |
| JP2003106724A (en) * | 2001-09-28 | 2003-04-09 | Lion Corp | Spray for reducing sweaty shoe |
| JP4879099B2 (en) * | 2007-06-22 | 2012-02-15 | 株式会社安部日鋼工業 | Sheath support structure |
| JP5972528B2 (en) * | 2010-12-02 | 2016-08-17 | 小林製薬株式会社 | Aerosol injection device |
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1998
- 1998-07-16 JP JP20161098A patent/JP3323812B2/en not_active Expired - Fee Related
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