JP3866393B2 - Cleaning method for hollow fiber membrane module - Google Patents
Cleaning method for hollow fiber membrane module Download PDFInfo
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- JP3866393B2 JP3866393B2 JP28379897A JP28379897A JP3866393B2 JP 3866393 B2 JP3866393 B2 JP 3866393B2 JP 28379897 A JP28379897 A JP 28379897A JP 28379897 A JP28379897 A JP 28379897A JP 3866393 B2 JP3866393 B2 JP 3866393B2
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- Prior art keywords
- hollow fiber
- fiber membrane
- cleaning
- membrane module
- 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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Description
【0001】
【発明の属する技術分野】
本発明は中空糸膜モジュールの洗浄方法に関し、特に汚濁性(殊に有機物の汚濁性)の高い液体を濾過する際の中空糸膜モジュールの洗浄方法に関する。
【0002】
【従来の技術】
従来、中空糸膜モジュールは、無菌水、飲料水、高純度水の製造や、空気の浄化といったいわゆる精密濾過の分野において多く使用されてきたが、近年、下水処理場における二次処理、三次処理や、浄化槽における固液分離、産業廃水中のss(浮遊懸濁物質)の固液分離、浄水場における河川水の直接濾過、工業用水道水の濾過、プール水の濾過等の高汚濁性水処理用途に用いる検討が様々な形で行われている。
【0003】
しかしながら、これらの用途においては濾過の継続にしたがって濾過膜に目詰まりが生じ、濾過差圧が上昇した。この濾過膜の目詰まりは、大きくは2つに分類され、一つは膜面への微粒子等の堆積である。これに対しては、クロスフロー濾過や、気液混合流によるスクラビング洗浄で洗浄することができる。もう一つは、有機物や微少な無機元素等の吸着に由来するファウリングであり、ファウリングを洗浄するためには薬液による洗浄が不可欠である。
【0004】
【発明が解決しようとする課題】
薬液洗浄は、一般的には中空糸膜モジュール浸漬用の薬液槽を別に用意し、その薬液槽中にモジュールを浸漬して洗浄する方法が一般的であり、洗浄効果は高い。しかし、この方法はモジュールの着脱操作が必要であり、操作が煩雑であった。
【0005】
それに変わる方法として、モジュールをインラインで洗浄する方法が検討されている。一般的な洗浄方法として、中空糸膜の外側から中空部に向かって濾過を行う中空糸膜モジュールに対して、洗浄時に洗浄薬液を中空部から外側へ逆通液する方法が採られている。しかしながら、この方法を膜面積の大きい中空糸膜モジュールに適用した場合には、モジュール内の中空糸膜全体に薬液が行き渡る前に薬液が中空糸膜面から滲み出してしまい、中空糸膜全体の薬液洗浄が困難であった。
【0006】
本発明の目的は、インラインで簡便に薬液洗浄できる中空糸膜モジュールの洗浄方法を提供することにある。
【0007】
【課題を解決するための手段】
すなわち、本発明は、中空糸膜の外側から中空部に向かって濾過を行う液体濾過用の中空糸膜モジュールを洗浄するに際して、中空糸膜の中空部に洗浄薬液を通液して循環させた後に、中空糸膜の中空部を加圧して洗浄薬液を中空糸膜を通過させる工程を少なくとも一回実施することを特徴とする中空糸膜モジュールの洗浄方法である。
【0008】
【発明の実施の形態】
以下、本発明の中空糸膜モジュールの洗浄方法について図面を参照しつつ説明する。図1は、本発明の洗浄方法の一例を示すフロー図である。
【0009】
本発明の洗浄方法が適用される中空糸膜モジュール濾過方式としては、浸漬吸引濾過、水頭差による自重濾過および加圧缶体内にモジュールを装着する加圧濾過いずれを採ることも可能であるが、加圧濾過を例にとり説明する。
【0010】
中空糸膜モジュールを用いた通常の加圧濾過時には、ポンプ1を作動させバルブ3を開き、バルブ4、5、6、7を閉じ濾過を行う。一方、洗浄時にはポンプ2を作動させ、バルブ3、4、7を閉じ、バルブ5、6を開き、薬液タンク10から薬液を中空糸膜の中空部内に通液し循環させる。十分な循環を実施し、中空糸膜中空部内が薬液で置き換えられた後、ポンプ2を停止しバルブ4、7を開き、バルブ3、5、6を閉じ、エアー圧をかけて中空糸膜中空部内の薬液を膜壁を通して中空糸膜の外側へ逆向きに通液させる。この操作により、中空糸膜モジュール8の中空糸膜の膜壁(膜内部)内のファウリングが薬品洗浄される。
【0011】
中空糸膜モジュールの構造には、大別すると中空糸膜の両端をそれぞれ別々に樹脂で固定する両端樹脂固定タイプと、中空糸膜をU字状に収束して樹脂で固定するかあるいは中空糸膜の一端は封止し片端の開口端を樹脂で固定する片端樹脂固定タイプがあるが、本発明の方法に用いる中空糸膜モジュールとしては両端樹脂固定タイプが好ましい。両端樹脂固定タイプの場合には、中空糸膜の中空部内への洗浄薬液の通液循環が容易かつ確実に実施できるからである。
【0012】
本発明の洗浄方法において洗浄薬液として使用する薬品は、中空糸膜や濾過システムを構成する部材に損傷を与えずファウリング物質を溶解あるいは酸化分解するものであれば特に限定されるものではない。その具体例としては、次亜塩素酸ソーダ、クロラミン、過酸化水素水、苛性ソーダ、塩酸、蓚酸、クエン酸等を挙げることができる。
【0013】
本発明の洗浄方法が適用される中空糸膜の材質も特に限定されず、ポリオレフィン、ポリスルフォン、PAN、セルロース系等任意のものが使用できる。耐薬品性の高さや、膜の強伸度の高さ等を考えると、ポリオレフィン系の素材が好ましい。
本発明の洗浄方法において、中空糸膜の中空部に洗浄薬液を通液して循環させるのは、中空糸膜の中空部内を薬液で完全に置換するとともに、中空糸膜の内部に対して薬液を十分に接触させるためである。この通液循環時間が短いと、膜に対する薬液の接触が不十分となり、十分な洗浄が達成できない。通液循環時間としては、20秒〜3時間程度が好ましい。薬液を通液循環した後の加圧操作は、連続的に実施してもよいし、間欠的に何回か加圧することにより洗浄薬液を膜内に浸透させてファウリング物質を溶解等させた後これを新たな洗浄薬液と交換するようにすることもできる。加圧操作の時間は、薬液の洗浄力によっても異なるが、通常、一回当たり5秒〜20分程度が好ましい。
【0014】
図2は、スクラビング洗浄の実施に適した中空糸膜モジュールであって、中空糸膜を緯糸とする編織物からなる中空糸膜を、その端部を開口状態に保ちつつ、中空糸膜に垂直な断面の形状が細長いほぼ矩型であるように合成樹脂で中空糸膜の両端が樹脂で別々に固定されてなる中空糸膜モジュールを示している。このタイプの中空糸膜モジュールに対して本発明の洗浄方法が効果的に適用することができる。
【0015】
【実施例】
実施例
図2に示した形状の中空糸膜モジュール(ステラポアーL、商品名、三菱レイヨン(株)製)を用いて生活排水の活性汚泥固液分離を浸漬吸引濾過法で実施することによって、膜の目詰まりが生じた三本の洗浄試験用モジュール(モジュールA、B、C)を用意した。なお、濾過初期の中空糸膜モジュールの差圧は5kPa、目詰まり後の差圧は35kPaであった。
【0016】
モジュールAについては、2000ppmの次亜塩素酸ソーダ水溶液の薬液タンクに2時間浸漬して洗浄した。モジュールBについては、2000ppmの次亜塩素酸ソーダ水溶液5Lに圧力100kPaを加えることで中空糸膜の中空部側から外側に向けて約5分間通液した。
モジュールCは、本発明の方法にしたがった洗浄を実施した。すなわち、中空糸膜モジュールを図1のような薬液配管に取り付け、2000ppmの次亜塩素酸ソーダ水溶液を中空糸膜の中空部内を流れるようにポンプで供給し、1時間中空糸膜の中空部内を通液循環させた。その後エアー圧100kPaを5分間加え、中空糸膜モジュール内部の薬液をすべて一次側へ押し出した。
このようにして薬液洗浄した後の各中空糸膜モジュールの差圧は、表1に示す通りであった。本発明の洗浄方法が適用された中空糸膜モジュールCは、薬液中に浸漬する洗浄方法を適用した中空糸膜モジュールAと同等の洗浄効果が達成された。
【0017】
【表1】
【図面の簡単な説明】
【図1】本発明の洗浄方法を説明するためのフロー図である。
【図2】本発明の洗浄方法に適した中空糸膜モジュールを示す模式図である。
【符号の説明】
1、2 ポンプ
3〜7 バルブ
8 中空糸膜モジュール
9 エアーベント
10 薬液タンク[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for cleaning a hollow fiber membrane module, and more particularly to a method for cleaning a hollow fiber membrane module when filtering a highly pollutant (particularly organic matter) liquid.
[0002]
[Prior art]
Conventionally, hollow fiber membrane modules have been widely used in the field of so-called microfiltration such as the production of aseptic water, drinking water and high-purity water, and purification of air. Recently, secondary treatment and tertiary treatment in sewage treatment plants Highly polluted water such as solid-liquid separation in septic tanks, solid-liquid separation of ss (suspended suspended solids) in industrial wastewater, direct filtration of river water in water purification plants, filtration of industrial tap water, filtration of pool water, etc. Studies for use in processing are being conducted in various forms.
[0003]
However, in these applications, the filtration membrane clogged as filtration continued, and the filtration differential pressure increased. The clogging of the filtration membrane is roughly classified into two, and one is accumulation of fine particles or the like on the membrane surface. On the other hand, it can wash | clean by cross-flow filtration or the scrubbing washing | cleaning by a gas-liquid mixed flow. The other is fouling derived from the adsorption of organic substances, minute inorganic elements, and the like. Cleaning with chemicals is indispensable for cleaning fouling.
[0004]
[Problems to be solved by the invention]
The chemical cleaning is generally performed by separately preparing a chemical bath for immersing the hollow fiber membrane module and immersing the module in the chemical bath for cleaning, and the cleaning effect is high. However, this method requires a module attachment / detachment operation, and the operation is complicated.
[0005]
As an alternative method, a method of cleaning the module in-line has been studied. As a general cleaning method, a method in which a cleaning chemical solution is reversely passed from the hollow portion to the outside during cleaning is employed for a hollow fiber membrane module that performs filtration from the outside of the hollow fiber membrane toward the hollow portion. However, when this method is applied to a hollow fiber membrane module having a large membrane area, the chemical solution oozes out from the hollow fiber membrane surface before the chemical solution spreads over the entire hollow fiber membrane in the module, The chemical cleaning was difficult.
[0006]
The objective of this invention is providing the washing | cleaning method of the hollow fiber membrane module which can carry out chemical | medical solution washing | cleaning simply in-line.
[0007]
[Means for Solving the Problems]
That is, in the present invention, when cleaning a hollow fiber membrane module for liquid filtration that performs filtration from the outside of the hollow fiber membrane toward the hollow portion, a cleaning chemical solution was passed through the hollow portion of the hollow fiber membrane and circulated. The method for cleaning a hollow fiber membrane module is characterized in that the step of pressurizing the hollow portion of the hollow fiber membrane and passing the cleaning chemical solution through the hollow fiber membrane is performed at least once.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a method for cleaning a hollow fiber membrane module of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing an example of the cleaning method of the present invention.
[0009]
As the hollow fiber membrane module filtration system to which the cleaning method of the present invention is applied, it is possible to adopt any of suction suction filtration, self-weight filtration due to water head difference and pressure filtration in which a module is mounted in a pressure can body. An explanation will be given taking pressure filtration as an example.
[0010]
During normal pressure filtration using a hollow fiber membrane module, the pump 1 is operated to open the
[0011]
The structure of the hollow fiber membrane module can be broadly divided into a both-end resin fixing type in which both ends of the hollow fiber membrane are separately fixed with a resin, and the hollow fiber membrane is converged into a U shape and fixed with a resin or hollow fiber There is a single-end resin fixing type in which one end of the membrane is sealed and the open end of one end is fixed with resin. However, a double-end resin fixing type is preferable as the hollow fiber membrane module used in the method of the present invention. This is because in the case of the both-end resin-fixed type, it is possible to easily and reliably carry out the circulation of the cleaning chemical liquid into the hollow portion of the hollow fiber membrane.
[0012]
The chemical used as the cleaning chemical in the cleaning method of the present invention is not particularly limited as long as it can dissolve or oxidatively decompose the fouling substance without damaging the hollow fiber membrane and the members constituting the filtration system. Specific examples thereof include sodium hypochlorite, chloramine, hydrogen peroxide, caustic soda, hydrochloric acid, oxalic acid, and citric acid.
[0013]
The material of the hollow fiber membrane to which the cleaning method of the present invention is applied is not particularly limited, and any material such as polyolefin, polysulfone, PAN, and cellulose can be used. In view of the high chemical resistance and the high strength of the film, a polyolefin-based material is preferable.
In the cleaning method of the present invention, the cleaning chemical solution is passed through the hollow portion of the hollow fiber membrane and circulated so that the inside of the hollow portion of the hollow fiber membrane is completely replaced with the chemical solution and the chemical solution is added to the inside of the hollow fiber membrane. It is for making it fully contact. When the liquid circulation time is short, the contact of the chemical with the membrane is insufficient, and sufficient cleaning cannot be achieved. The liquid circulation time is preferably about 20 seconds to 3 hours. The pressurizing operation after circulating the chemical solution may be carried out continuously, or by intermittently pressurizing several times, the cleaning chemical solution penetrates into the membrane to dissolve the fouling substance, etc. Later, this can be replaced with a new cleaning chemical. Although the time for the pressurizing operation varies depending on the cleaning power of the chemical solution, it is usually preferably about 5 seconds to 20 minutes per time.
[0014]
FIG. 2 shows a hollow fiber membrane module suitable for carrying out scrubbing cleaning, and a hollow fiber membrane made of a knitted fabric having a hollow fiber membrane as a weft is perpendicular to the hollow fiber membrane while keeping its end open. A hollow fiber membrane module is shown in which both ends of a hollow fiber membrane are separately fixed with a synthetic resin so that the cross-sectional shape is a long and substantially rectangular shape. The cleaning method of the present invention can be effectively applied to this type of hollow fiber membrane module.
[0015]
【Example】
EXAMPLE By carrying out the activated sludge solid-liquid separation of domestic wastewater by the immersion suction filtration method using the hollow fiber membrane module (STELLAPORE L, trade name, manufactured by Mitsubishi Rayon Co., Ltd.) having the shape shown in FIG. Three cleaning test modules (modules A, B, and C) in which clogging occurred were prepared. The differential pressure of the hollow fiber membrane module at the beginning of filtration was 5 kPa, and the differential pressure after clogging was 35 kPa.
[0016]
Module A was cleaned by immersing it in a chemical tank of 2000 ppm sodium hypochlorite aqueous solution for 2 hours. As for module B, a pressure of 100 kPa was applied to 5 L of 2000 ppm sodium hypochlorite aqueous solution to allow the solution to pass from the hollow portion side to the outside of the hollow fiber membrane for about 5 minutes.
Module C was cleaned according to the method of the present invention. That is, the hollow fiber membrane module is attached to a chemical pipe as shown in FIG. 1, and a 2000 ppm sodium hypochlorite aqueous solution is supplied by a pump so as to flow in the hollow portion of the hollow fiber membrane, The liquid was circulated. Thereafter, an air pressure of 100 kPa was applied for 5 minutes to push out all the chemical solution inside the hollow fiber membrane module to the primary side.
The differential pressure of each hollow fiber membrane module after the chemical solution washing was as shown in Table 1. The hollow fiber membrane module C to which the cleaning method of the present invention was applied achieved a cleaning effect equivalent to that of the hollow fiber membrane module A to which the cleaning method immersed in a chemical solution was applied.
[0017]
[Table 1]
[Brief description of the drawings]
FIG. 1 is a flowchart for explaining a cleaning method of the present invention.
FIG. 2 is a schematic view showing a hollow fiber membrane module suitable for the cleaning method of the present invention.
[Explanation of symbols]
1, 2 Pump 3-7
Claims (3)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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JP28379897A JP3866393B2 (en) | 1997-10-16 | 1997-10-16 | Cleaning method for hollow fiber membrane module |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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JP28379897A JP3866393B2 (en) | 1997-10-16 | 1997-10-16 | Cleaning method for hollow fiber membrane module |
Publications (2)
Publication Number | Publication Date |
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JPH11114384A JPH11114384A (en) | 1999-04-27 |
JP3866393B2 true JP3866393B2 (en) | 2007-01-10 |
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JP28379897A Expired - Fee Related JP3866393B2 (en) | 1997-10-16 | 1997-10-16 | Cleaning method for hollow fiber membrane module |
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Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
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JP4382275B2 (en) * | 2000-12-15 | 2009-12-09 | 前澤工業株式会社 | Membrane module cleaning method |
JP4386702B2 (en) * | 2003-09-30 | 2009-12-16 | 株式会社クボタ | Chemical cleaning device |
JP2005211847A (en) * | 2004-01-30 | 2005-08-11 | Tsukishima Kikai Co Ltd | Filtering device |
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1997
- 1997-10-16 JP JP28379897A patent/JP3866393B2/en not_active Expired - Fee Related
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