JP2008246424A - Cleaning method of hollow fiber membrane module and hollow fiber membrane filtering apparatus - Google Patents

Cleaning method of hollow fiber membrane module and hollow fiber membrane filtering apparatus Download PDF

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JP2008246424A
JP2008246424A JP2007093115A JP2007093115A JP2008246424A JP 2008246424 A JP2008246424 A JP 2008246424A JP 2007093115 A JP2007093115 A JP 2007093115A JP 2007093115 A JP2007093115 A JP 2007093115A JP 2008246424 A JP2008246424 A JP 2008246424A
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hollow fiber
fiber membrane
raw water
free chlorine
membrane
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Tsutomu Miura
勤 三浦
Seiichi Nakahara
清一 中原
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Kuraray Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning method of a hollow fiber membrane module operable in filtration for a long period stably and continuously. <P>SOLUTION: In the physical cleaning process of the external pressure type hollow fiber membrane module fed with raw liquid from the outside of the hollow fiber membrane and discharging filtrate from the inside, liquid containing free chlorine is fed to the raw liquid side to perform bubbling cleaning. In this case, the concentration of the free chlorine in the liquid fed to the raw liquid is controlled to make the concentration of the free chlorine in the liquid in the raw liquid side after bubbling 0.1 mg/L or more. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は中空糸膜モジュールの洗浄方法および中空糸膜ろ過装置に関する。   The present invention relates to a method for cleaning a hollow fiber membrane module and a hollow fiber membrane filtration device.

近年、分離膜に関する技術開発が進み、水のろ過をはじめ様々な用途に広く用いられている。分離膜の素材としては有機高分子、セラミック、燒結金属などが提案され、分離膜の形状としては中空糸膜、管状膜、平膜、モノリスなどが提案され、また分離膜の孔径としてはイオン類を分離できる逆浸透膜（ＲＯ）、タンパク質、ウイルスなどの高分子成分を分離できる限外ろ過膜（ＵＦ）、細菌類などの微粒子を分離できる精密ろ過膜（ＭＦ）などが提案され、これらを組み合わせて多種多様の分離膜が提案され、実用化されているものも多い。特に中空糸膜は、単位容積あたりの膜面積を大きく確保でき、さらに種々の素材、孔径およびモジュール形状のものから選択できることから適用範囲が広く、広範な用途で使用されている。   In recent years, technological development related to separation membranes has progressed, and it has been widely used for various applications including water filtration. Organic polymers, ceramics, sintered metals, etc. have been proposed as materials for separation membranes, and hollow fiber membranes, tubular membranes, flat membranes, monoliths, etc. have been proposed as the shape of separation membranes. Proposals include reverse osmosis membranes (RO) that can separate proteins, ultrafiltration membranes (UF) that can separate high molecular components such as proteins and viruses, and microfiltration membranes (MF) that can separate microparticles such as bacteria. Many different separation membranes have been proposed and put into practical use. In particular, the hollow fiber membrane can secure a large membrane area per unit volume, and can be selected from various materials, pore diameters and module shapes, so that it has a wide range of applications and is used in a wide range of applications.

しかし、分離膜によるろ過の過程では、目詰まりとよばれる膜表面の汚染や微細孔の詰まりが生じ、経時的に透過流束の低下が生じる。例えば主に微粒子成分の除去を目的とする限外ろ過膜（ＵＦ）や精密ろ過膜（ＭＦ）では、ＳＳと呼ばれる原液中の懸濁物質等が膜表面に付着し、または微多孔に侵入し、経時的に透過流束の低下が生じる。そこで、安定して長期的にろ過運転を継続するためには、濾過条件の設定と同時に有効な分離膜の洗浄方法の開発が不可欠とされている。   However, in the process of filtration using a separation membrane, the membrane surface contamination called clogging and clogging of micropores occur, and the permeation flux decreases with time. For example, in ultrafiltration membranes (UF) and microfiltration membranes (MF) mainly for the purpose of removing particulate components, suspended substances in the stock solution called SS adhere to the membrane surface or penetrate into the micropores. The permeation flux decreases with time. Therefore, in order to continue the filtration operation stably for a long time, it is indispensable to develop an effective separation membrane cleaning method at the same time as setting the filtration conditions.

従来、分離膜の洗浄方法として、種々の方法が検討されてきたが、これらは物理的洗浄と、化学的洗浄（薬品洗浄ともいう）とに大別できる。物理的洗浄としては、スポンジボール、高圧水流などにより強制的に付着物質をかき取る方法、水、膜ろ過水などの液体をろ液側から原液側へ通過させる液体逆洗法（例えば、特許文献１ 参照）、加圧気体をろ液側から原液側へ通過させる気体逆洗法（例えば、特許文献２、３ 参照）、原液側に気泡を噴出させるバブリング法、超音波法、電気泳動法などをはじめ、多種多様の方法が提案されている（例えば、非特許文献１ 参照）。また、化学的洗浄としては、酸、アルカリ水溶液、洗浄剤などの薬液により、付着物を溶解除去する方法が知られている。これらは分離膜の素材、形状、孔径などの特性や目詰まり物質の特性に応じ、適宜選択して単独または組み合わせて実施される（例えば、非特許文献２ 参照）。   Conventionally, various methods have been studied as separation membrane cleaning methods. These methods can be broadly classified into physical cleaning and chemical cleaning (also referred to as chemical cleaning). Physical cleaning includes a method of forcibly scraping off adhering substances using a sponge ball, high-pressure water flow, etc., and a liquid back-washing method in which a liquid such as water or membrane filtered water is passed from the filtrate side to the stock solution side (for example, patent documents) 1), a gas backwashing method in which a pressurized gas is passed from the filtrate side to the stock solution side (see, for example, Patent Documents 2 and 3), a bubbling method in which bubbles are ejected to the stock solution side, an ultrasonic method, an electrophoresis method, etc. A wide variety of methods have been proposed (for example, see Non-Patent Document 1). As chemical cleaning, a method of dissolving and removing deposits with a chemical solution such as an acid, an aqueous alkaline solution, or a cleaning agent is known. These are carried out by appropriately selecting them according to characteristics such as the material, shape and pore diameter of the separation membrane and characteristics of the clogging substance (for example, see Non-Patent Document 2).

特開昭５１−１１０４８２号公報JP-A-51-110482 特開昭５３−１０８８８２号公報JP-A-53-108882 特表平１−５００７３２号公報Japanese translation of PCT publication 1-500732 化学工学会・膜分離技術ワーキンググループ編、「ユーザーのための実用膜分離技術」、日刊工業新聞社発行、１９９６年４月３０日、Ｐ２４３〜２４８Chemical Engineering Society / Membrane Separation Technology Working Group, “Practical membrane separation technology for users”, published by Nikkan Kogyo Shimbun, April 30, 1996, pages 243-248 化学工学会・膜分離技術ワーキンググループ編、「ユーザーのための実用膜分離技術」、日刊工業新聞社発行、１９９６年４月３０日、Ｐ２５１〜２６１Chemical Engineering Society / Membrane Separation Technology Working Group, “Practical membrane separation technology for users”, published by Nikkan Kogyo Shimbun, April 30, 1996, P251-261

一方、活性汚泥法に代表される生物処理は、下水処理をはじめとして有機物、窒素およびリンを含む排水の浄化方法として広く用いられている。従来は河川や海洋に放流するために処理を行っていたが、近年その処理水の再利用が行われるようになってきた。生物処理水を再利用する場合、通常砂ろ過や膜ろ過により夾雑物を除去した後、必要により活性炭処理、逆浸透膜ろ過、イオン交換などにより再利用に必要な水質まで精製する。一般に生物処理水には多量の微生物が含まれるため、夾雑物除去手法として精密ろ過（ＭＦ）膜や限外ろ過（ＵＦ）膜などの膜ろ過手法を適用する場合、目詰まりを生じやすいことから、特に効果的な物理洗浄手法の開発が重要となる。   On the other hand, biological treatment represented by the activated sludge method is widely used as a purification method for wastewater containing organic matter, nitrogen and phosphorus, including sewage treatment. Conventionally, treatment has been performed for release into rivers and oceans, but in recent years, the treated water has been reused. When biologically treated water is reused, it is usually purified to the water quality necessary for reuse by removing activated impurities by sand filtration or membrane filtration, if necessary, by activated carbon treatment, reverse osmosis membrane filtration, ion exchange and the like. Since biologically treated water generally contains a large amount of microorganisms, clogging is likely to occur when membrane filtration techniques such as microfiltration (MF) membrane and ultrafiltration (UF) membrane are applied as a contaminant removal technique. In particular, the development of an effective physical cleaning technique is important.

従来、中空糸膜で生物処理水のろ過を行う場合、目詰まりを回避するために生物処理水にオゾンを溶解させてからろ過する方法や、次亜塩素酸ナトリウムなどの酸化剤を含む液体による液体逆洗を行うことが提案されてきた。ただし生物処理水にオゾンを溶解させてから膜ろ過する方法では、オゾン発生装置が非常に高価かつ大電力を必要とする上、現在実用化されているほとんどの膜モジュールがオゾンにより分解作用を受けて劣化するため、あらかじめ活性炭などによりオゾンを除去してからろ過する必要がある。一方、フッ素系高分子からなる膜のようにオゾンに対して耐性を有する膜モジュールも提案されているが、非常に高価であったり、孔径やモジュールの形状および大きさが限られていたりするため、一般的とはいえない。また次亜塩素酸ナトリウムなどの酸化剤を含む液体による液体逆洗では、必ずしも満足できる洗浄効果が得られない上に、膜ろ過水側配管や膜モジュールの膜ろ過水側が酸化剤を含む液体により汚染されるため、膜ろ過水を再利用する場合に酸化剤の除去や還元処理が必要となる場合もあり、好ましくない。   Conventionally, when filtering biologically treated water with a hollow fiber membrane, it is possible to dissolve ozone in the biologically treated water in order to avoid clogging, or a liquid containing an oxidizing agent such as sodium hypochlorite. It has been proposed to perform liquid backwashing. However, in the method of membrane filtration after dissolving ozone in biologically treated water, the ozone generator is very expensive and requires high power, and most membrane modules currently in practical use are decomposed by ozone. Therefore, it is necessary to filter after removing ozone with activated carbon in advance. On the other hand, membrane modules that are resistant to ozone, such as membranes made of fluoropolymers, have also been proposed, but they are very expensive and have limited pore sizes and module shapes and sizes. It's not common. In addition, liquid backwashing with a liquid containing an oxidizing agent such as sodium hypochlorite does not always provide a satisfactory cleaning effect, and the membrane filtration water side piping and the membrane filtration water side of the membrane module are not filled with a liquid containing an oxidizing agent. Since it is contaminated, removal of the oxidizing agent or reduction treatment may be necessary when the membrane filtered water is reused, which is not preferable.

本発明の目的は、新規な外圧型中空糸膜モジュールの物理洗浄方法およびそのために用いることのできる中空糸膜ろ過装置を提供することにある。   An object of the present invention is to provide a novel physical cleaning method for an external pressure type hollow fiber membrane module and a hollow fiber membrane filtration device that can be used therefor.

上記の課題を解決する本発明の中空糸膜モジュールの洗浄方法は、中空糸膜の外側から原水を供給し内側からろ過水を取り出す外圧型中空糸膜モジュールにおいて、原水側に遊離塩素を含む液体を供給してバブリング洗浄を実施し、その際原水側に供給する液体の遊離塩素濃度を、バブリング洗浄後の原水側液体中の遊離塩素濃度が０．１ｍｇ／Ｌ以上となるように制御する。   The method for cleaning a hollow fiber membrane module of the present invention that solves the above problem is a liquid containing free chlorine on the raw water side in an external pressure type hollow fiber membrane module that supplies raw water from the outside of the hollow fiber membrane and takes out filtrated water from the inside. In this case, the free chlorine concentration of the liquid supplied to the raw water side is controlled so that the free chlorine concentration in the raw water side liquid after the bubbling cleaning is 0.1 mg / L or more.

また本発明の中空糸膜モジュールの洗浄方法は、中空糸膜の外側から原水を供給し内側からろ過水を取り出す外圧型中空糸膜モジュールと、原水側に遊離塩素を含む液体を供給する手段と、原水側に気体を噴出させる手段とを備え、原水側に遊離塩素を含む液体を供給してバブリング洗浄を行うよう制御する膜ろ過装置を用いて行うことができる。   The hollow fiber membrane module cleaning method of the present invention includes an external pressure type hollow fiber membrane module that supplies raw water from the outside of the hollow fiber membrane and takes out filtrated water from the inside, and means for supplying a liquid containing free chlorine to the raw water side. And a means for ejecting gas on the raw water side, and a membrane filtration device that controls the bubbling cleaning by supplying a liquid containing free chlorine to the raw water side.

本発明の中空糸膜モジュールの洗浄方法によって、長期間安定的に連続したろ過運転が可能となる。本発明の中空糸膜ろ過装置は、上記本発明の中空糸膜モジュールの洗浄方法のために用いることが有効である。   The method for cleaning a hollow fiber membrane module of the present invention enables a continuous filtration operation stably for a long period of time. It is effective to use the hollow fiber membrane filtration device of the present invention for the method for cleaning the hollow fiber membrane module of the present invention.

本発明で使用される中空糸膜の素材としては特に限定されず、形状、孔径などの要求特性に応じて適宜選択することができる。例えば有機高分子系素材としては、ポリオレフィン系樹脂、ポリスルホン系樹脂、ポリエーテルスルホン系樹脂、エチレンービニルアルコール共重合体系樹脂、ポリアクリロニトリル系樹脂、酢酸セルロース系樹脂、ポリフッ化ビニリデン系樹脂、ポリパーフルオロエチレン系樹脂、ポリメタクリル酸エステル系樹脂、ポリエステル系樹脂、ポリアミド系樹脂などが挙げられ、他成分を共重合したもの、他の素材をブレンドしたもの、親水化処理などの処理を施したものでもよい。   The material of the hollow fiber membrane used in the present invention is not particularly limited, and can be appropriately selected according to required characteristics such as shape and pore diameter. For example, organic polymer materials include polyolefin resins, polysulfone resins, polyethersulfone resins, ethylene-vinyl alcohol copolymer resins, polyacrylonitrile resins, cellulose acetate resins, polyvinylidene fluoride resins, polypars. Fluoroethylene resin, polymethacrylic acid ester resin, polyester resin, polyamide resin, etc. are listed, those obtained by copolymerizing other components, those blended with other materials, and those subjected to treatment such as hydrophilization But you can.

また、製造方法は特に限定されることはなく、素材の特性および所望する分離膜の形状や性能に応じて、公知の方法から適宜選択した方法を採用することができる。   Further, the production method is not particularly limited, and a method appropriately selected from known methods can be adopted according to the characteristics of the material and the desired shape and performance of the separation membrane.

本発明で使用される中空糸膜の孔径は特に限定されないが、０．００１〜５ミクロンの範囲内であることが、高い透水性を有し、濾過効率が低下するおそれが小さいことから好ましい。なお、ここでいう孔径とは、コロイダルシリカ、エマルジョン、ラテックスなどの粒子径が既知の各種基準物質を中空糸膜で濾過した際に、その９０％が排除される基準物質の粒子径をいう。孔径は均一であることが好ましい。限外ろ過膜であれば、上記のような基準物質の粒子径に基づいて、孔径を求めることは不可能であるが、分子量が既知の蛋白質を用いて同様の測定を行ったときに、分画分子量が３０００以上であるものが好ましい。   The pore diameter of the hollow fiber membrane used in the present invention is not particularly limited, but it is preferably within the range of 0.001 to 5 microns because it has high water permeability and is less likely to reduce the filtration efficiency. Here, the pore diameter refers to the particle diameter of a reference material from which 90% is excluded when various reference substances with known particle diameters such as colloidal silica, emulsion, and latex are filtered through a hollow fiber membrane. The pore diameter is preferably uniform. In the case of an ultrafiltration membrane, it is impossible to determine the pore size based on the particle size of the reference material as described above, but when a similar measurement is performed using a protein with a known molecular weight, Those having a molecular weight of 3000 or more are preferred.

本発明において、該中空糸膜はモジュール化されてろ過に使用される。モジュールの形態は、ろ過方法、ろ過条件、洗浄方法などに応じて適宜選択することができ、１本または複数本の膜エレメントを装着して中空糸膜モジュールを構成しても良い。例えば数十本から数十万本の中空糸膜を束ねてモジュール内でＵ字型にしたもの、中空糸繊維束の一端を適当なシール材により一括封止したもの、中空糸繊維束の一端を適当なシール材により１本ずつ固定されていない状態（フリー状態）で封止したもの、中空糸繊維束の両端を開口したものなどが挙げられる。また、形状も特に限定されることはなく、例えば円筒状であってもスクリーン状であってもよい。特に中空糸繊維束の一端を適当なシール材により１本ずつ固定されていない状態（フリー状態）で封止したもの（片端フリー構造）の中空糸膜モジュールは、バブリング洗浄による膜付着物質の剥離および排出を効果的に行うことができるため好ましい。   In the present invention, the hollow fiber membrane is modularized and used for filtration. The form of the module can be appropriately selected according to the filtration method, filtration conditions, washing method, and the like, and a hollow fiber membrane module may be configured by mounting one or a plurality of membrane elements. For example, bundled dozens to hundreds of thousands of hollow fiber membranes into a U-shape in the module, one end of a hollow fiber bundle bundled together with an appropriate sealing material, one end of a hollow fiber bundle Are sealed in a state where they are not fixed one by one with a suitable sealing material (free state), and those in which both ends of the hollow fiber bundle are opened. Further, the shape is not particularly limited, and may be, for example, a cylindrical shape or a screen shape. In particular, hollow fiber membrane modules in which one end of a hollow fiber bundle is sealed in a state where it is not fixed one by one with a suitable sealing material (free state) (one-end free structure) are used for peeling membrane adhering substances by bubbling cleaning In addition, it is preferable because it can be effectively discharged.

本発明で使用される中空糸膜モジュールよるろ過の方式としては、外圧全ろ過、外圧循環ろ過の中から所望の処理条件、処理性能に応じて適宜選択することができる。膜寿命の点ではろ過膜表面の洗浄を同時に行うことのできる循環方式が好ましく、設備の単純さ、設置コスト、運転コストの点では全ろ過方式が好ましい。また膜モジュールを原水槽などの槽に浸漬し、吸引または水頭差によりろ過を行うことも可能である。   The filtration method using the hollow fiber membrane module used in the present invention can be appropriately selected from external pressure total filtration and external pressure circulation filtration according to desired treatment conditions and treatment performance. In terms of membrane life, a circulation method capable of simultaneously cleaning the surface of the filtration membrane is preferable, and in terms of simplicity of equipment, installation cost, and operation cost, a total filtration method is preferable. It is also possible to immerse the membrane module in a tank such as a raw water tank and perform filtration by suction or water head difference.

本発明においては、原水側に遊離塩素を含む液体を供給してバブリング洗浄を実施し、その際原水側に供給する液体の遊離塩素濃度を、バブリング洗浄後の原水側液体中の遊離塩素濃度が０．１ｍｇ／Ｌ以上となるように制御する。以下本発明の実施の態様について、図面を用いて詳しく説明する。   In the present invention, bubbling cleaning is performed by supplying a liquid containing free chlorine to the raw water side. At that time, the free chlorine concentration of the liquid supplied to the raw water side is the free chlorine concentration in the raw water side liquid after bubbling cleaning. Control to be 0.1 mg / L or more. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

図１は上記の洗浄方法を行うために使用することができる外圧型中空糸膜モジュールの一例の概略構成図である。該中空糸膜モジュールは中空糸膜１、ケーシング２および接着樹脂３からなり、ケーシング２の内部は接着樹脂３により原水側Ａと膜ろ過水側Ｂに仕切られている。原液側Ａには原水入口４、原水溢出口５、濃縮液排出口６、バブリング用気体注入口７および含遊離塩素液体注入口８を備えており、膜ろ過水側Ｂには膜ろ過水出口９を備えている。原水入口４から原水側Ａに供給された原水は、中空糸膜１の外表面でろ過されて膜ろ過水側Ｂである中空糸膜内部に移動し、膜ろ過水出口９を通じて系外へ排出される。   FIG. 1 is a schematic configuration diagram of an example of an external pressure type hollow fiber membrane module that can be used to perform the above-described cleaning method. The hollow fiber membrane module includes a hollow fiber membrane 1, a casing 2, and an adhesive resin 3, and the inside of the casing 2 is partitioned by the adhesive resin 3 into a raw water side A and a membrane filtrate side B. The raw solution side A has a raw water inlet 4, a raw water overflow outlet 5, a concentrate discharge port 6, a bubbling gas inlet 7 and a free chlorine-containing liquid inlet 8, and a membrane filtered water side B has a membrane filtered water outlet 9 is provided. The raw water supplied from the raw water inlet 4 to the raw water side A is filtered on the outer surface of the hollow fiber membrane 1, moves to the inside of the hollow fiber membrane which is the membrane filtrate side B, and is discharged out of the system through the membrane filtrate outlet 9. Is done.

本発明の洗浄方法の一例を、図２にしたがって説明する。図２は上記の洗浄方法を行うために使用することができる膜ろ過装置の一例の概略構成図である。原水は必要に応じて前処理装置１１で前処理が行われた後原水槽１２に供給される。ここで前処理とは、ストレーナーなどによる夾雑物除去、硫酸ばん土およびポリ塩化アルミニウムなどの凝集剤による凝集処理、活性炭などによる吸着などが挙げられ、適宜単独または組み合わせて実施することが出来る。次いでろ過工程について説明する。すなわち全てのバルブを閉じた状態から、原水入口バルブ１５、原水溢出口バルブ１８および膜ろ過水出口バルブ１６を開き、原水ポンプ１３を作動させて中空糸膜モジュール１４に原水を導入し、原水溢出口バルブ１８より原水が溢出した後原水溢出口バルブ１８を閉じてろ過を開始する。膜ろ過水は膜ろ過水出口バルブ１６を通じて系外へ排出される。ただし、ろ過時間の経過に伴い目詰まりが進行してろ過能力が低下するため、続いて本発明の方法により中空糸膜を洗浄する。すなわち、原水ポンプ１３を停止した後、ろ過工程で開いている原水入口バルブ１５および膜ろ過水出口バルブ１６を閉じてろ過を停止し、次いで原水溢出口バルブ１８を開いた後逆洗エアー入口バルブ１９を開いて中空糸膜モジュール１４の膜ろ過水側に加圧空気を注入して逆洗操作を行う。所定時間経過後逆洗エアー入口バルブ１９を閉じ、次いで遊離塩素含有液体入口バルブ２１を開き、遊離塩素含有液体注入ポンプ２２を作動させて遊離塩素液体タンク２３に貯留した遊離塩素含有液体を中空糸膜モジュールの原水側に注入し、その後バブリングエアー入口バルブ２０を開いて中空膜モジュールの原水側に空気を吹き込み、バブリング洗浄を行う。所定時間バブリング洗浄を行った後、バブリングエアー入口バルブ２０を閉じてバブリング洗浄を停止し、濃縮液排出口バルブ１７を開いて中空糸膜モジュールの原水側の濃縮液を系外へ排出する。上述した洗浄工程終了後、濃縮液排出口バルブ１７を閉じ、ろ過工程へ戻る。   An example of the cleaning method of the present invention will be described with reference to FIG. FIG. 2 is a schematic configuration diagram of an example of a membrane filtration device that can be used to perform the above-described cleaning method. The raw water is supplied to the raw water tank 12 after being pretreated by the pretreatment device 11 as necessary. Here, the pretreatment includes removal of impurities using a strainer and the like, agglomeration treatment with a coagulant such as sulfated clay and polyaluminum chloride, adsorption with activated carbon and the like, and can be carried out alone or in combination as appropriate. Next, the filtration step will be described. That is, after all the valves are closed, the raw water inlet valve 15, the raw water overflow outlet valve 18 and the membrane filtrate outlet valve 16 are opened, and the raw water pump 13 is operated to introduce the raw water into the hollow fiber membrane module 14, and the raw water overflow After the raw water overflows from the outlet valve 18, the raw water overflow outlet valve 18 is closed to start filtration. The membrane filtrate is discharged out of the system through the membrane filtrate outlet valve 16. However, since the clogging progresses as the filtration time elapses and the filtration capacity decreases, the hollow fiber membrane is subsequently washed by the method of the present invention. That is, after the raw water pump 13 is stopped, the raw water inlet valve 15 and the membrane filtrate outlet valve 16 which are opened in the filtration process are closed to stop the filtration, and then the raw water overflow outlet valve 18 is opened and then the backwash air inlet valve is opened. 19 is opened and pressurized air is injected into the membrane filtrate side of the hollow fiber membrane module 14 to perform a backwash operation. After a predetermined time has elapsed, the backwash air inlet valve 19 is closed, then the free chlorine-containing liquid inlet valve 21 is opened, and the free chlorine-containing liquid stored in the free chlorine liquid tank 23 by operating the free chlorine-containing liquid injection pump 22 is hollow fiber. After injecting into the raw water side of the membrane module, the bubbling air inlet valve 20 is opened and air is blown into the raw water side of the hollow membrane module to perform bubbling cleaning. After performing the bubbling cleaning for a predetermined time, the bubbling air inlet valve 20 is closed to stop the bubbling cleaning, and the concentrated solution outlet valve 17 is opened to discharge the concentrated solution on the raw water side of the hollow fiber membrane module out of the system. After completion of the above-described washing process, the concentrate outlet valve 17 is closed and the process returns to the filtration process.

遊離塩素を含む液体としては、次亜塩素酸ナトリウム水溶液、次亜塩素酸カルシウム水溶液、塩素化イソシアヌル酸水溶液などが挙げられる。 Examples of the liquid containing free chlorine include a sodium hypochlorite aqueous solution, a calcium hypochlorite aqueous solution, and a chlorinated isocyanuric acid aqueous solution.

本発明において、遊離塩素を含む液体の注入量は、バブリング洗浄後の原液側液体中の遊離塩素濃度が０．１ｍｇ／Ｌ以上となるように制御する。例えば微生物などの有機物や鉄イオンなど、遊離塩素により酸化作用を受けやすい物質を含有する液体をろ過した中空糸膜モジュールを本発明の洗浄方法により洗浄する場合、注入した遊離塩素を含む液体がそれらを酸化する反応で消費されるため、過剰に添加する必要がある。制御の方法としては、例えば定期的にバブリング洗浄後の原液側液体中の遊離塩素濃度を測定して注入量を設定することができるが、遊離塩素濃度測定装置などを使用して自動的に注入量を設定することもできる。なお、バブリング洗浄後の原液側液体中の遊離塩素濃度が０．１ｍｇ／Ｌ未満の場合、洗浄効果が不十分となるおそれがある。 In the present invention, the injection amount of the liquid containing free chlorine is controlled so that the free chlorine concentration in the stock solution side liquid after the bubbling washing is 0.1 mg / L or more. For example, when a hollow fiber membrane module obtained by filtering a liquid containing a substance that is easily oxidized by free chlorine, such as organic substances such as microorganisms or iron ions, is washed by the washing method of the present invention, the liquid containing injected free chlorine It is necessary to add in excess because it is consumed in the reaction of oxidizing. As a control method, for example, the free chlorine concentration in the stock solution side liquid after bubbling washing can be measured periodically to set the injection amount, but it is automatically injected using a free chlorine concentration measuring device etc. You can also set the amount. In addition, when the free chlorine concentration in the stock solution side liquid after the bubbling cleaning is less than 0.1 mg / L, the cleaning effect may be insufficient.

これまでに述べてきた本発明の洗浄方法は、一般に数分から数時間ごとに行われる物理洗浄操作ごとに実施することができるが、数回もしくは数十回の物理洗浄毎に１回、すなわち間欠的に実施することも可能である。 The cleaning method of the present invention described so far can be performed for each physical cleaning operation generally performed every several minutes to several hours, but once every several or several tens of physical cleanings, that is, intermittently. It is also possible to implement it.

以下、実施例により本発明をより詳細に説明する。   Hereinafter, the present invention will be described in more detail with reference to examples.

標準活性汚泥法によりＢＯＤ除去され、沈殿槽にて自然沈降により固液分離された、浮遊物質約１０ｍｇ／Ｌを含む生物処理水を原水とし、ポリスルホン系樹脂からなり、孔径０．１μｍである中空糸膜よりなる片端フリー構造で膜面積７ｍ2 の中空糸膜モジュールを使用して、外圧全ろ過方式、ろ過速度３５０Ｌ／時の条件で定流量ろ過を行った。中空糸膜の物理洗浄は、シーケンスコントロールにより３０分に１回、中空糸膜モジュールの膜ろ過水側に圧力０．２ＭＰａの空気を導入することにより１０秒間加圧操作し、次いで中空膜モジュールの原水側に、濃縮液中の遊離塩素濃度が０．５から２．０ｍｇ／Ｌの範囲内の値となるような量の次亜塩素酸ナトリウム水溶液を注入し、その後中空糸膜モジュールの原水側の下部より圧力０．１ＭＰａの空気を１．６８Ｎｍ３／ｈｒの流量で１分間噴出させて行い、下部濃縮液排出バルブを開いて濃縮液を排出した。次亜塩素酸ナトリウム水溶液の注入量は、濃縮液中の遊離塩素濃度を定期的に測定しながら、０．５から１．０ｍｇ／Ｌの範囲内の値となるよう制御した。濾過運転期間中、膜間差圧を定期的に測定し、膜間差圧が０．１５ＭＰａに達するまでの濾過時間を中空糸膜モジュールの濾過寿命とした場合、濾過寿命は１３８日間であった。 BOD removed by standard activated sludge method, solid-liquid separated by natural sedimentation in a sedimentation tank, biologically treated water containing about 10 mg / L of suspended solids as raw water, made of polysulfone resin, hollow with a pore size of 0.1 μm Using a hollow fiber membrane module having a single-end free structure made of yarn membrane and a membrane area of 7 m @ 2, constant flow filtration was performed under the conditions of an external pressure total filtration method and a filtration rate of 350 L / hour. The physical cleaning of the hollow fiber membrane is performed once every 30 minutes by sequence control, and is pressurized for 10 seconds by introducing air at a pressure of 0.2 MPa to the membrane filtration water side of the hollow fiber membrane module. An amount of sodium hypochlorite aqueous solution is injected into the raw water side so that the free chlorine concentration in the concentrate is in the range of 0.5 to 2.0 mg / L, and then the raw water side of the hollow fiber membrane module The air was discharged from the lower part at a pressure of 0.1 MPa at a flow rate of 1.68 Nm 3 / hr for 1 minute, and the lower concentrate discharge valve was opened to discharge the concentrate. The injection amount of the sodium hypochlorite aqueous solution was controlled to be a value within the range of 0.5 to 1.0 mg / L while periodically measuring the free chlorine concentration in the concentrate. During the filtration operation, when the transmembrane pressure difference is measured periodically and the filtration time until the transmembrane pressure pressure reaches 0.15 MPa is defined as the filtration life of the hollow fiber membrane module, the filtration life is 138 days. .

比較例１
実施例１において、物理洗浄時に次亜塩素酸ナトリウム水溶液の注入を行わない以外は同様にして、生物処理水のろ過を行った。膜間差圧で評価したろ過寿命は２３日間であり、実施例１に比較して明らかに短かった。 Comparative Example 1
In Example 1, the biologically treated water was filtered in the same manner except that the sodium hypochlorite aqueous solution was not injected during physical cleaning. The filtration life evaluated by the transmembrane pressure difference was 23 days, which was clearly shorter than that of Example 1.

比較例２
実施例１において、中空糸膜の物理洗浄として、次亜塩素酸ナトリウム水溶液を注入した膜ろ過水により液体逆洗浄を２０秒間行った後、その後中空糸膜モジュールの原水側の下部より圧力０．１ＭＰａの空気を１．６８Ｎｍ３／ｈｒの流量で１分間噴出させて行い、下部濃縮液排出バルブを開いて濃縮液を排出した以外は同様にして、生物処理水のろ過を行った。膜間差圧で評価した濾過寿命は８８日間であった。またろ過運転再開時には、ろ過水に高濃度の遊離塩素が検出された。 Comparative Example 2
In Example 1, as physical washing of the hollow fiber membrane, liquid back washing was performed for 20 seconds with membrane filtered water into which an aqueous sodium hypochlorite solution was injected. The biologically treated water was filtered in the same manner except that 1 MPa of air was ejected at a flow rate of 1.68 Nm 3 / hr for 1 minute and the lower concentrate discharge valve was opened to discharge the concentrate. The filtration life evaluated by transmembrane pressure difference was 88 days. When the filtration operation was resumed, high concentration of free chlorine was detected in the filtered water.

本発明で使用することができる外圧型中空糸膜モジュールの一例を示す図である。It is a figure which shows an example of the external pressure type | mold hollow fiber membrane module which can be used by this invention. 本発明の中空糸膜ろ過装置の一例を示す図である。It is a figure which shows an example of the hollow fiber membrane filtration apparatus of this invention.

符号の説明Explanation of symbols

１：中空糸膜
２：ケーシング
３：接着樹脂
４：原水入口
５：原水溢出口
６：濃縮液排出口
７：バブリング用気体注入口
８：含遊離塩素液体注入口
９：膜ろ過水出口
Ａ：原水側
Ｂ：膜ろ過水側
１１：前処理装置
１２：原水槽
１３：原水ポンプ
１４：中空糸膜モジュール
１５：原水入口バルブ
１６：膜ろ過水出口バルブ
１７：濃縮液排出口バルブ
１８：原水溢出口バルブ
１９：逆洗エアー入口バルブ
２０：バブリングエアー入口バルブ
２１：遊離塩素含有液体入口バルブ
２２：遊離塩素含有液体注入ポンプ
２３：遊離塩素含有液体タンク
２４：エアーコンプレッサー 1: Hollow fiber membrane 2: Casing 3: Adhesive resin 4: Raw water inlet 5: Raw water overflow outlet 6: Concentrated liquid outlet 7: Gas inlet for bubbling 8: Free chlorine containing liquid inlet 9: Membrane filtrate outlet A: Raw water side B: Membrane filtrate side 11: Pretreatment device 12: Raw water tank 13: Raw water pump 14: Hollow fiber membrane module 15: Raw water inlet valve 16: Membrane filtered water outlet valve 17: Concentrate outlet valve 18: Raw water overflow Outlet valve 19: Backwash air inlet valve 20: Bubbling air inlet valve 21: Free chlorine containing liquid inlet valve 22: Free chlorine containing liquid injection pump 23: Free chlorine containing liquid tank 24: Air compressor

Claims (2)

中空糸膜の外側から原水を供給し内側からろ過水を取り出す外圧型中空糸膜モジュールにおいて、原水側に遊離塩素を含む液体を供給してバブリング洗浄を実施し、その際原水側に供給する液体の遊離塩素濃度を、バブリング洗浄後の原水側液体中の遊離塩素濃度が０．１ｍｇ／Ｌ以上となるように制御することを特徴とする中空糸膜モジュールの洗浄方法。   In an external pressure type hollow fiber membrane module that supplies raw water from the outside of the hollow fiber membrane and takes out filtrated water from the inside, a liquid containing free chlorine is supplied to the raw water side to perform bubbling cleaning, and in this case, the liquid supplied to the raw water side The method for cleaning a hollow fiber membrane module is characterized in that the free chlorine concentration in the raw water-side liquid after bubbling cleaning is controlled to be 0.1 mg / L or more. 中空糸膜の外側から原水を供給し内側からろ過水を取り出す外圧型中空糸膜モジュールと、原水側に遊離塩素を含む液体を供給する手段と、原水側に気体を噴出させる手段とを備え、原水側に遊離塩素を含む液体を供給してバブリング洗浄を行うよう制御することを特徴とする膜ろ過装置。   An external pressure type hollow fiber membrane module for supplying raw water from the outside of the hollow fiber membrane and taking out filtered water from the inside; means for supplying a liquid containing free chlorine to the raw water side; and means for jetting gas to the raw water side, A membrane filtration apparatus characterized in that a liquid containing free chlorine is supplied to the raw water side to perform bubbling cleaning.
JP2007093115A 2007-03-30 2007-03-30 Cleaning method of hollow fiber membrane module and hollow fiber membrane filtering apparatus Pending JP2008246424A (en)

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KR100949349B1 (en) * 2009-09-14 2010-03-26 주식회사 에스디알앤디 Membrane filtration apparatus and membrane cleaning method thereof
WO2012165748A1 (en) * 2011-05-27 2012-12-06 서울대학교산학협력단 Method for washing a filtration membrane using a novel disinfectant
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USD779631S1 (en) 2015-08-10 2017-02-21 Koch Membrane Systems, Inc. Gasification device

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