JP2009241043A - Backwashing method of membrane filter apparatus - Google Patents

Backwashing method of membrane filter apparatus Download PDF

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JP2009241043A
JP2009241043A JP2008094229A JP2008094229A JP2009241043A JP 2009241043 A JP2009241043 A JP 2009241043A JP 2008094229 A JP2008094229 A JP 2008094229A JP 2008094229 A JP2008094229 A JP 2008094229A JP 2009241043 A JP2009241043 A JP 2009241043A
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membrane
water
cleaning
water chamber
washing
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Yoshiro Kobayashi
芳郎 小林
Yuki Togo
雄喜 東郷
Toshisuke Yamazaki
俊祐 山崎
Noboru Takemura
昇 竹村
Toshio Sano
利夫 佐野
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Mitsui Engineering and Shipbuilding Co Ltd
Yuasa Membrane Systems Co Ltd
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Mitsui Engineering and Shipbuilding Co Ltd
Yuasa Membrane Systems Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a backwashing method of a membrane filter apparatus capable of effectively removing an adhesion substance on the surface of a membrane not perfectly removed by pressure washing and capable of being stably operated for a long period. <P>SOLUTION: The membrane filter apparatus is partitioned into a raw water chamber 1A and a treatment water chamber 1B, has a structure wherein a filter cylinder 7 opened on the side of the treatment water chamber 1B is installed to filter ascending raw water, and is constituted so that a washing water supply pipe 4 is connected to the treatment water chamber 1B and a washing wastewater discharge pipe 6 is connected to the raw water chamber 1A. The backwashing method of this membrane filter apparatus has a first membrane washing process of closing an on-off valve 61 of the washing wastewater discharge pipe 6 in a state that the treatment water chamber 1B is filled with washing water and, after air is injected to pressurize the washing water, opening the on-off valve 61 to transmit the washing water through the membrane at a stroke to backwash the membrane and a second membrane washing process of supplying the washing water to the treatment water chamber 1B in a state that the on-off valve 61 is opened after the first membrane washing process to transmit the same through the membrane at a flow velocity lower than that in the first membrane washing process to backwash the membrane. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は膜濾過装置の逆洗方法に関し、詳しくは、加圧洗浄によっても除去しきれない膜表面の付着物質を効果的に除去することができ、長期に安定した運転を行うことのできる膜濾過装置の逆洗方法に関する。   The present invention relates to a method for backwashing a membrane filtration device, and more specifically, a membrane capable of effectively removing adhering substances on the membrane surface that cannot be removed even by pressure washing, and capable of stable operation over a long period of time. The present invention relates to a backwashing method for a filtration device.

従来、濾過槽内が仕切板により原水室と処理水室とに区画され、原水室内に、仕切板を貫通して処理水室側に開口する袋状の膜を備えた多数の濾過筒が設置され、原水室に入った原水を膜により濾過して処理水として処理水室内に集水する構造の膜濾過装置が知られている(特許文献1、2)。   Conventionally, the inside of a filtration tank is partitioned into a raw water chamber and a treated water chamber by a partition plate, and a large number of filter cylinders provided with a bag-like membrane that penetrates the partition plate and opens to the treated water chamber side are installed in the raw water chamber. A membrane filtration device having a structure in which raw water entering a raw water chamber is filtered through a membrane and collected as treated water in the treated water chamber is known (Patent Documents 1 and 2).

このような膜濾過装置では、原水中に含まれる目詰まり物質によって膜表面が経時的に汚れて目詰まりを起こす。このため、洗浄水を濾過時とは逆方向に流すことにより膜表面から目詰まり物質を剥離させて洗浄する逆洗運転を濾過運転と交互に行い、定期的に膜の機能回復を図る必要がある。例えば、海水をくみ上げて船舶のバラストタンク内に移送する場合、くみ上げられた海水を膜濾過装置によって濾過すると、膜表面に粒子が徐々に堆積してやがて目を塞いでしまう。この粒子の多くはSi、Al、Fe等の無機物であり、海底の泥に由来すると思われる。このため、定期的に逆洗運転を行うことにより、膜表面に堆積した粒子を剥離させる必要がある。   In such a membrane filtration apparatus, the clogging substance contained in the raw water clogs the membrane surface over time and causes clogging. For this reason, it is necessary to reverse the washing operation by separating the clogging substances from the membrane surface by flowing the washing water in the direction opposite to that during filtration, and performing the washing operation alternately with the filtration operation to periodically restore the function of the membrane. is there. For example, when seawater is pumped and transferred into a ballast tank of a ship, if the pumped seawater is filtered by a membrane filtration device, particles gradually accumulate on the membrane surface and eventually block the eyes. Most of these particles are inorganic substances such as Si, Al, Fe, etc., and are thought to be derived from the seabed mud. For this reason, it is necessary to exfoliate the particles deposited on the film surface by periodically performing a backwash operation.

一方、海水を濾過してバラスト水とする膜濾過装置では、膜濾過処理は船舶上で行われることになるので、逆洗運転する際の洗浄水量には限りがある。このため少ない洗浄水量で効果的に逆洗することが望まれる。
特開平5−245312号公報 特開2006−15296号公報
On the other hand, in a membrane filtration device that filters seawater into ballast water, the membrane filtration process is performed on a ship, so the amount of washing water during backwash operation is limited. For this reason, it is desirable to backwash effectively with a small amount of washing water.
Japanese Patent Laid-Open No. 5-245313 JP 2006-15296 A

本発明者は、かかる膜濾過装置における膜の逆洗を少ない洗浄水量で効果的に行う方法として、濾過槽内を密閉した状態で、洗浄水を満たした処理水室内に空気を所定の圧力となるまで注入した後、原水室側を開放して洗浄水を一気に排出させることにより、洗浄水を濾過時とは逆方向に高速に透過させ、膜表面の付着物質を除去する加圧逆洗方法を試みている。この方法は付着物質による膜の目詰まりを少ない洗浄水量で除去するのに極めて効果的である。   As a method for effectively performing backwashing of a membrane in such a membrane filtration device with a small amount of washing water, the inventor has introduced air into a treated water chamber filled with washing water with a predetermined pressure in a state where the inside of the filtration tank is sealed. After injecting until it reaches the pressure, the raw water chamber side is opened and the washing water is discharged at once, allowing the washing water to permeate at a high speed in the direction opposite to that during filtration, and removing the adhered substances on the membrane surface. Are trying. This method is extremely effective in removing clogging of the film due to adhered substances with a small amount of washing water.

しかし、この逆洗方法でも、付着物質を完全には除去しきれず、一部が膜表面に付着したままとなってしまう場合のあることが判明した。加圧逆洗は通常複数回繰り返し行う、この付着物質は加圧逆洗を複数回繰り返しても除去されずに残ってしまう。   However, it has been found that even with this backwashing method, the adhering substance cannot be completely removed, and a part of the adhering substance may remain attached to the film surface. The pressure backwash is usually repeated a plurality of times, and this adhered substance remains without being removed even if the pressure backwash is repeated a plurality of times.

図7に示すように、膜100の表面は、表面積を大きくするために山部と谷部とが交互に配置されるように多数の折り部を形成したプリーツ状を呈しており、その谷部101(濾過方向に沿って見た場合に谷となる部分)に、原水中の泥や砂(シルト)200が付着し、これが加圧逆洗によっても除去しきれず、徐々に蓄積していることが判明した。   As shown in FIG. 7, the surface of the film 100 has a pleated shape in which a large number of folds are formed so that peaks and valleys are alternately arranged to increase the surface area. Mud and sand (silt) 200 in the raw water adheres to 101 (portion that becomes a valley when viewed along the filtration direction), and this cannot be removed even by pressure backwashing and is gradually accumulated. There was found.

これは、逆洗時に高圧の洗浄水を瞬間的に透過させる加圧洗浄では、プリーツの山部102(濾過方向に沿って見た場合に山となる部分)の先端付近に瞬間的な洗浄水の流れが集中してしまい、プリーツの谷部101内の膜表面はその洗浄水の流れとほぼ平行な面となるために、谷部101内の膜表面から孔を垂直な方向に通過する洗浄水の流れが十分に形成されず、この部位の付着物質を除去する力が不十分となり、シルト200は完全には抜け出て行かないためであると考えられる。従って、このようなシルト200が蓄積した状態で通常の濾過運転を行うと、膜が早急に目詰まりを起こしてしまうことにより膜間差圧が上昇してしまい、長期に安定した運転ができない問題があった。   This is because, in the pressure cleaning that instantaneously permeates high-pressure cleaning water during backwashing, instantaneous cleaning water is provided near the tip of the pleat peak 102 (the peak when viewed along the filtration direction). Since the flow of water concentrates and the film surface in the valley portion 101 of the pleat becomes a plane substantially parallel to the flow of the washing water, the cleaning passes through the holes in the vertical direction from the film surface in the valley portion 101. This is probably because the water flow is not sufficiently formed, the force for removing the adhered substances at this site is insufficient, and the silt 200 does not completely escape. Therefore, when a normal filtration operation is performed in a state where such a silt 200 is accumulated, the membrane is rapidly clogged, resulting in an increase in the transmembrane pressure difference, and a long-term stable operation cannot be performed. was there.

そこで、本発明は、加圧洗浄によっても除去しきれない膜表面の付着物質を効果的に除去することができ、長期に安定した運転を行うことのできる膜濾過装置の逆洗方法を提供することを課題とする。   Accordingly, the present invention provides a method for backwashing a membrane filtration device that can effectively remove adhered substances on the membrane surface that cannot be removed even by pressure washing, and can perform stable operation over a long period of time. This is the issue.

本発明の他の課題は、以下の記載により明らかとなる。   Other problems of the present invention will become apparent from the following description.

上記課題は、以下の各発明によって解決される。   The above problems are solved by the following inventions.

(請求項1)
濾過槽内が仕切板により原水室と処理水室とに区画され、前記原水室内に、前記仕切板を貫通して前記処理水室側に開口する袋状の膜を備えた多数の濾過筒が設置され、前記原水室に入った原水が該原水室内を上向流しながら前記膜により濾過され処理水として前記濾過筒内を上昇して前記処理水室内に集水される構造を有し、前記処理水室には開閉弁を介して洗浄水供給管が接続され、前記原水室には開閉弁を介して洗浄排水排出管が接続された膜濾過装置の逆洗方法において、
前記処理水室に洗浄水を満たした状態で前記洗浄排水排出管の開閉弁を閉じ、前記処理水室内に空気を注入して洗浄水を加圧した後、前記洗浄排水排出管の開閉弁を開くことにより、加圧された洗浄水を一気に膜透過させて前記膜の逆洗浄を行う第1の膜洗浄工程と、
前記第1の膜洗浄工程の後、前記洗浄排水排出管の開閉弁を開いた状態で前記洗浄水供給管から前記処理水室に洗浄水を供給することにより、前記第1の膜洗浄工程よりも小さい流速で洗浄水を膜透過させて前記膜の逆洗浄を行う第2の膜洗浄工程とを有することを特徴とする膜濾過装置の逆洗方法。
(Claim 1)
The inside of the filtration tank is partitioned into a raw water chamber and a treated water chamber by a partition plate, and a number of filter cylinders provided with a bag-like membrane that penetrates the partition plate and opens to the treated water chamber side in the raw water chamber. The raw water that has been installed and enters the raw water chamber is filtered by the membrane while flowing upward in the raw water chamber, and has a structure in which the raw water rises in the filter cylinder as treated water and is collected in the treated water chamber, In the backwashing method of the membrane filtration apparatus, the cleaning water supply pipe is connected to the treated water chamber via an on-off valve, and the cleaning water discharge pipe is connected to the raw water chamber via the on-off valve.
After the treatment water chamber is filled with washing water, the on-off valve of the washing drainage pipe is closed, air is injected into the treatment water chamber to pressurize the washing water, and then the on-off valve of the washing drainage discharge pipe is opened. A first membrane cleaning step for performing reverse cleaning of the membrane by opening the pressurized cleaning water through the membrane at a stretch by opening,
After the first membrane cleaning step, by supplying cleaning water from the cleaning water supply pipe to the treated water chamber with the opening / closing valve of the cleaning drainage pipe opened, the first membrane cleaning step And a second membrane cleaning step of performing reverse cleaning of the membrane by allowing the cleaning water to pass through the membrane at a low flow rate.

(請求項2)
前記第2の膜洗浄工程における前記洗浄水の流速は、1〜3m/sであることを特徴とする請求項1記載の膜濾過装置の逆洗方法。
(Claim 2)
The backwashing method for a membrane filtration device according to claim 1, wherein a flow rate of the washing water in the second membrane washing step is 1 to 3 m / s.

(請求項3)
前記第2の膜洗浄工程における前記洗浄水の供給時間は、10〜90秒であることを特徴とする請求項1又は2記載の膜濾過装置の逆洗方法。
(Claim 3)
The backwashing method for a membrane filtration device according to claim 1 or 2, wherein the cleaning water supply time in the second membrane cleaning step is 10 to 90 seconds.

(請求項4)
前記膜は、プリーツ状の膜であることを特徴とする請求項1、2又は3記載の膜濾過装置の逆洗方法。
(Claim 4)
4. The method of backwashing a membrane filtration device according to claim 1, wherein the membrane is a pleated membrane.

(請求項5)
前記第1の膜洗浄工程において、前記処理水室内の洗浄水中に微細気泡を導入することを特徴とする請求項1〜4のいずれかに記載の膜濾過装置の逆洗方法。
(Claim 5)
The backwashing method for a membrane filtration device according to any one of claims 1 to 4, wherein in the first membrane cleaning step, fine bubbles are introduced into the cleaning water in the treated water chamber.

(請求項6)
前記原水は船舶のバラストタンクに供給するためのバラスト水であることを特徴とする請求項1〜5のいずれかに記載の膜濾過装置の逆洗方法。
(Claim 6)
The method for backwashing a membrane filtration device according to any one of claims 1 to 5, wherein the raw water is ballast water to be supplied to a ballast tank of a ship.

以下、本発明の実施の形態について図面を用いて説明する。   Hereinafter, embodiments of the present invention will be described with reference to the drawings.

図1は本発明の逆洗方法を実施するのに好適な膜濾過装置の一例を示す概略断面図である。   FIG. 1 is a schematic sectional view showing an example of a membrane filtration apparatus suitable for carrying out the backwashing method of the present invention.

図中、1は濾過槽である。濾過槽1は円筒竪型に形成されることが好ましく、内部は仕切板11により、原水が導入される原水室1Aと濾過された後の処理水が集水される処理水室1Bとに区画されている。原水室1Aの下方側部には原水供給口12が設けられ、処理水室1Bの上部には処理水排出口13が設けられている。   In the figure, 1 is a filtration tank. The filtration tank 1 is preferably formed in a cylindrical bowl shape, and the inside is partitioned by a partition plate 11 into a raw water chamber 1A into which raw water is introduced and a treated water chamber 1B in which treated water after filtration is collected. Has been. A raw water supply port 12 is provided at the lower side of the raw water chamber 1A, and a treated water discharge port 13 is provided at the upper portion of the treated water chamber 1B.

原水供給口12には原水供給管2が接続され、開閉弁21によって原水の供給経路が開閉可能とされている。本発明において、原水としては、船舶のバラストタンクに供給するためのバラスト水(海水や淡水)が好ましく用いられる。バラスト水として海水を原水とする場合、濾過対象となる物質としては、動物性プランクトン、植物性プランクトン、微生物、Si、Al、Feなどの元素又はその酸化物や塩化物などの無機物、その他、懸濁物質(SS)、ゲル状物質などがある。   A raw water supply pipe 2 is connected to the raw water supply port 12, and a supply path of the raw water can be opened and closed by an on-off valve 21. In the present invention, as raw water, ballast water (seawater or fresh water) for supplying to a ballast tank of a ship is preferably used. When seawater is used as the ballast water, the substances to be filtered include zooplankton, phytoplankton, microorganisms, elements such as Si, Al, and Fe, inorganic substances such as oxides and chlorides, and other matters. There are suspended substances (SS), gel-like substances and the like.

処理水排出口13には処理水排出管3が接続され、開閉弁31によって処理水の排出経路が開閉可能とされている。   A treated water discharge pipe 3 is connected to the treated water discharge port 13, and a discharge path for treated water can be opened and closed by an on-off valve 31.

また、処理水排出口13には、濾過膜の逆洗用の洗浄水を供給するための洗浄水供給管4が接続され、開閉弁41によって洗浄水の供給経路が開閉可能とされている。洗浄水供給管4には洗浄水供給ポンプ42が介設されており、洗浄水タンク43内の洗浄水を処理水排出口13から濾過槽1内の処理水室1Bに供給する。   Further, the treated water discharge port 13 is connected with a washing water supply pipe 4 for supplying washing water for backwashing the filtration membrane, and a supply path for the washing water can be opened and closed by an on-off valve 41. A cleaning water supply pump 42 is interposed in the cleaning water supply pipe 4 to supply cleaning water in the cleaning water tank 43 from the processing water discharge port 13 to the processing water chamber 1B in the filtration tank 1.

更に、処理水排出口13には、逆洗時に処理水室1B内に洗浄水が満たされている状態で空気を供給して該処理水室1B内を加圧するための加圧用空気供給管5の一端が接続され、開閉弁51によって加圧用空気の供給経路が開閉可能とされている。加圧用空気供給管5の他端は加圧空気を供給するための加圧用空気供給源52に接続されている。加圧用空気供給源52には例えばコンプレッサーを用いることができる。加圧用空気供給管5には処理水室1B内に送られる加圧空気の圧力を計測する圧力計53が設けられている。   Furthermore, the pressurized water supply pipe 5 for supplying air to the treated water discharge port 13 in a state where the treated water chamber 1B is filled with the washing water during backwashing and pressurizing the treated water chamber 1B. Is connected, and the supply path of the pressurizing air can be opened and closed by the on-off valve 51. The other end of the pressurizing air supply pipe 5 is connected to a pressurizing air supply source 52 for supplying pressurized air. For example, a compressor can be used as the pressurizing air supply source 52. The pressurizing air supply pipe 5 is provided with a pressure gauge 53 for measuring the pressure of the pressurized air sent into the treated water chamber 1B.

原水室1Aの底部には洗浄排水排出口14が設けられている。洗浄排水排出口14には洗浄排水排出管6が接続され、開閉弁61によって洗浄排水の排出経路が開閉可能とされている。   A washing drain discharge port 14 is provided at the bottom of the raw water chamber 1A. A cleaning drainage discharge pipe 6 is connected to the cleaning drainage outlet 14, and a cleaning drainage discharge path can be opened and closed by an on-off valve 61.

なお、洗浄水供給管4及び加圧用空気供給管5は、それぞれを処理水排出口13とは別に処理水室1B内に供給可能に接続するようにしてもよい。   The wash water supply pipe 4 and the pressurizing air supply pipe 5 may be connected to the treated water chamber 1B separately from the treated water discharge port 13 so that they can be supplied.

7は仕切板11に吊り下げられた濾過筒であり、該濾過筒7は多孔製の円筒形の支持体71と濾過膜72によって構成されている。   Reference numeral 7 denotes a filtration cylinder suspended from the partition plate 11, and the filtration cylinder 7 is composed of a porous cylindrical support 71 and a filtration membrane 72.

支持体71の材質には、例えばポリエチレンを用いることができる。支持体71は、処理水室1Bに処理水を送液可能なように、該処理水室1B側に向けて開口する上部開口73を有している。支持体71の表面は網目状に形成されてもよいし、あるいは多数の孔が形成されたものでもよい。支持体71表面の開口率は40%〜70%の範囲が好ましく、45%〜65%の範囲がより好ましく、50%〜65%の範囲が更に好ましい。   For example, polyethylene can be used as the material of the support 71. The support 71 has an upper opening 73 that opens toward the treated water chamber 1B so that treated water can be fed to the treated water chamber 1B. The surface of the support 71 may be formed in a mesh shape or may be formed with a large number of holes. The opening ratio on the surface of the support 71 is preferably in the range of 40% to 70%, more preferably in the range of 45% to 65%, and still more preferably in the range of 50% to 65%.

濾過膜72は、精密濾過膜や限外濾過膜などを用いることができるが、好ましいのは精密濾過膜である。本発明に好ましく用いることができる精密濾過膜は市販品として入手でき、例えば、株式会社ユアサメンブレンシステム製「ユミクロンメンブレンフィルター」などを使用できる。   The filtration membrane 72 can be a microfiltration membrane or an ultrafiltration membrane, but a microfiltration membrane is preferred. The microfiltration membrane that can be preferably used in the present invention can be obtained as a commercial product, for example, “Yumicron membrane filter” manufactured by Yuasa Membrane System Co., Ltd. can be used.

濾過膜72は袋状に形成されており、図2に示すように、支持体71の外周に被覆されている。この濾過膜72は、同図に示すように、長さ方向にプリーツ加工されたプリーツ状の濾過膜であることが好ましい。   The filtration membrane 72 is formed in a bag shape, and is coated on the outer periphery of the support 71 as shown in FIG. As shown in the figure, the filtration membrane 72 is preferably a pleated filtration membrane that is pleated in the length direction.

濾過筒7は、仕切板11に多数吊り下げられ、原水室1A内に配置される。その本数は濾過槽1の大きさ、原水の処理量に応じて適宜決められる。   A large number of filter cylinders 7 are suspended from the partition plate 11 and arranged in the raw water chamber 1A. The number is appropriately determined according to the size of the filtration tank 1 and the amount of raw water treated.

8は微細気泡吐出部であり、濾過槽1の処理水室1B内に配置されている。この微細気泡吐出部8には多孔部材を用いることができる。微細気泡吐出部8は空気供給管81を介して空気供給源82と接続されており、この空気供給源82を稼動させることにより、処理水室1B内に微細気泡を導入させる。空気供給源82としてはコンプレッサーを用いることができる。   Reference numeral 8 denotes a fine bubble discharge unit, which is disposed in the treated water chamber 1B of the filtration tank 1. A porous member can be used for the fine bubble discharge portion 8. The fine bubble discharge unit 8 is connected to an air supply source 82 via an air supply pipe 81. By operating the air supply source 82, fine bubbles are introduced into the treated water chamber 1B. A compressor can be used as the air supply source 82.

この微細気泡を導入するに際しては、加圧用空気供給源52から加圧用空気供給管5を介して供給される加圧空気より高い圧力で空気供給源82から微細気泡を吐出する必要がある。気泡の吐出圧力は、処理水室1Bの加圧状態の圧力より50〜100kPa高く設定することが気泡を良好に吐出する上で好ましい。微細気泡の直径は、濾過膜72を透過させる観点から、濾過膜72の孔径と同等程度が好ましい。この直径は多孔部材の孔径によって規定される。これら微細気泡を導入する構成は、本発明において好ましく設けられる。   When introducing the fine bubbles, it is necessary to discharge the fine bubbles from the air supply source 82 at a pressure higher than the pressurized air supplied from the pressurization air supply source 52 via the pressurization air supply pipe 5. The bubble discharge pressure is preferably set 50 to 100 kPa higher than the pressure in the pressurized state of the treatment water chamber 1B in order to discharge the bubbles well. The diameter of the fine bubbles is preferably about the same as the pore diameter of the filtration membrane 72 from the viewpoint of allowing the filtration membrane 72 to permeate. This diameter is defined by the pore diameter of the porous member. The configuration for introducing these fine bubbles is preferably provided in the present invention.

かかる膜濾過装置において、原水の処理を行う濾過運転時、原水は、原水供給管2から原水供給口12を経由して原水室1Aに導入され、原水室1A内を上向流して、濾過膜72を通過することによって濾過される。濾過膜72によって濾過された処理水は、濾過筒71内を更に上方に向かって進み、上部開口73から処理水室1Bに集水され、処理水排出口13から処理水排出管3を経由して排出される。   In such a membrane filtration apparatus, during a filtration operation in which raw water is treated, raw water is introduced from the raw water supply pipe 2 into the raw water chamber 1A via the raw water supply port 12, and flows upward in the raw water chamber 1A, so that the filtration membrane Filter by passing through 72. The treated water filtered by the filtration membrane 72 proceeds further upward in the filter cylinder 71, is collected into the treated water chamber 1 </ b> B from the upper opening 73, and passes through the treated water discharge pipe 3 from the treated water discharge port 13. Discharged.

このようにして濾過膜72による原水の処理を継続すると、次第に濾過膜72の目詰まりが生じるので、濾過膜72の逆洗浄が必要になる。本発明において、逆洗運転は第1の膜洗浄工程と第2の膜洗浄工程との2段階で行うことを特徴としている。以下、各工程について説明する。   If the raw water treatment by the filtration membrane 72 is continued in this manner, the filtration membrane 72 is gradually clogged, so that the filtration membrane 72 needs to be back-washed. In the present invention, the backwashing operation is performed in two stages of a first film cleaning process and a second film cleaning process. Hereinafter, each step will be described.

第1の膜洗浄工程は、加圧された洗浄水を処理水室1B側から原水室1A側に向けて一気に膜透過させる工程である。この工程では、原水供給管2の開閉弁21を閉じて原水の供給を停止させた後、処理水室1Bに洗浄水供給管4から逆洗用の洗浄水を供給する。洗浄水は、洗浄水タンク43から洗浄水供給ポンプ42の駆動によって供給される。このとき洗浄排水排出管6の開閉弁61及び処理水排出管3の開閉弁31は閉じた状態とし、処理水室1B内を洗浄水で満たす。この洗浄水が満たされた処理水室1Bに、加圧空気供給管5から加圧空気を注入することで、処理水室1B内の洗浄水を加圧する。   The first membrane cleaning step is a step of allowing the pressurized cleaning water to pass through the membrane all at once from the treated water chamber 1B side toward the raw water chamber 1A side. In this step, the on / off valve 21 of the raw water supply pipe 2 is closed to stop the supply of raw water, and then cleaning water for backwashing is supplied from the cleaning water supply pipe 4 to the treated water chamber 1B. The cleaning water is supplied from the cleaning water tank 43 by driving the cleaning water supply pump 42. At this time, the on-off valve 61 of the cleaning / drainage pipe 6 and the on-off valve 31 of the treated water discharge pipe 3 are closed, and the inside of the treated water chamber 1B is filled with washing water. By injecting pressurized air from the pressurized air supply pipe 5 into the treated water chamber 1B filled with the washed water, the washed water in the treated water chamber 1B is pressurized.

このとき、空気供給源82を稼動させることにより微細気泡吐出部8から微細気泡を生成させることが好ましい。すなわち、洗浄水供給管4から処理水室1B内に洗浄水を供給して該処理水室1B内が洗浄水で満たされた状態で、空気供給源82を稼動させることにより微細気泡吐出部8から微細気泡を生成させる。   At this time, it is preferable to generate fine bubbles from the fine bubble discharge unit 8 by operating the air supply source 82. That is, by supplying cleaning water from the cleaning water supply pipe 4 into the treatment water chamber 1B and operating the air supply source 82 in a state where the treatment water chamber 1B is filled with the cleaning water, the fine bubble discharge unit 8 is operated. To produce fine bubbles.

処理水室1B内が洗浄水で満たされたら、開閉弁51を開けて加圧用空気供給源52を稼動させることにより、同じく処理水室1B内に加圧空気を供給し、処理水室1B内の洗浄水を加圧する。洗浄水を加圧するのは、洗浄排水排出管16の開閉弁61を開けて洗浄水を洗浄排水排出口14から外部に排出する際に、処理水室1B内の洗浄水を濾過膜72を通過させて一気に原水室1A側に移動させ、濾過膜72の付着物質を除去させるためである。   When the inside of the treated water chamber 1B is filled with cleaning water, the open air valve 51 is opened and the pressurized air supply source 52 is operated to supply pressurized air into the treated water chamber 1B. Pressurize the wash water. The cleaning water is pressurized by opening the on-off valve 61 of the cleaning drainage discharge pipe 16 and passing the cleaning water in the treated water chamber 1B through the filter membrane 72 when the cleaning water is discharged from the cleaning drainage outlet 14 to the outside. This is to move the raw water chamber 1A to the raw water chamber 1A at a stretch and remove the adhered substances on the filtration membrane 72.

この加圧時の圧力は、濾過膜72のバブルポイント以上の圧力とすることが好ましい。圧力は加圧用空気供給管5に設けられた圧力計53によって計測することができる。処理水室1B内を濾過膜72のバブルポイント以上の圧力で加圧することにより、処理水室1B内に導入された微細気泡Bは、図3に示すように、濾過膜72の孔72aを通過する。このとき、濾過膜72の表面の付着物質(ゲル状物質なども含む)Xの大部分は一緒に除去される。   The pressure at the time of pressurization is preferably a pressure equal to or higher than the bubble point of the filtration membrane 72. The pressure can be measured by a pressure gauge 53 provided in the pressurizing air supply pipe 5. By pressurizing the inside of the treatment water chamber 1B at a pressure higher than the bubble point of the filtration membrane 72, the fine bubbles B introduced into the treatment water chamber 1B pass through the holes 72a of the filtration membrane 72 as shown in FIG. To do. At this time, most of the adhered substances (including gel-like substances) X on the surface of the filtration membrane 72 are removed together.

また、濾過膜72を通過して原水室1A側に出た微細気泡Bは、図4に示すように、濾過膜72の膜面を叩きながら上昇することにより、更に表面の付着物質の除去を助長させる。   Further, as shown in FIG. 4, the fine bubbles B that have passed through the filtration membrane 72 and exited toward the raw water chamber 1 </ b> A rise while hitting the membrane surface of the filtration membrane 72, thereby further removing the adhered substances on the surface. Encourage.

濾過膜72のバブルポイントは、濾過膜72を気泡が通過する最低圧力であり、このバブルポイントは、膜の孔径、膜の表面張力などによって決まる。本発明における実験例では、孔径が0.4〜0.9μmの範囲の精密濾過膜72に対して、加圧力を110〜160kPaとすることにより、気泡が膜を通過した。一般には、加圧空気による加圧力は、300〜500kPaとすることが好ましい。   The bubble point of the filtration membrane 72 is the lowest pressure at which bubbles pass through the filtration membrane 72, and this bubble point is determined by the pore diameter of the membrane, the surface tension of the membrane, and the like. In the experimental example of the present invention, bubbles were passed through the membrane by applying a pressure of 110 to 160 kPa to the microfiltration membrane 72 having a pore diameter in the range of 0.4 to 0.9 μm. Generally, it is preferable that the pressurization force by pressurized air shall be 300-500 kPa.

一方、第2の膜洗浄工程はかかる第1の膜洗浄工程の後に行われる。第2の膜洗浄工程は、第1の膜洗浄工程において、加圧されて一気に濾過膜72を通過した洗浄水を洗浄排水排出管6から排出した後、その洗浄排水排出管6の開閉弁61を開いた状態で、洗浄水供給管4から処理水室1Bに更に洗浄水を供給し、その洗浄水を濾過膜72に透過させる。このときの洗浄水は、洗浄水供給ポンプ42の作動によって供給されるだけであり、加圧用空気供給源52による加圧は行わない。従って、第1の膜洗浄工程よりも小さい流速で洗浄水を処理水室1B側から原水室1A側へ向けて緩慢に膜透過させて濾過膜72の逆洗浄を行う。   On the other hand, the second film cleaning step is performed after the first film cleaning step. In the second membrane cleaning step, after the cleaning water that has been pressurized and passed through the filter membrane 72 in the first membrane cleaning step is discharged from the cleaning drainage discharge pipe 6, the on-off valve 61 of the cleaning drainage discharge pipe 6 is used. In the state where is opened, the cleaning water is further supplied from the cleaning water supply pipe 4 to the treated water chamber 1B, and the cleaning water is permeated through the filtration membrane 72. The cleaning water at this time is only supplied by the operation of the cleaning water supply pump 42 and is not pressurized by the pressurizing air supply source 52. Therefore, the filtration membrane 72 is reversely cleaned by slowly allowing the cleaning water to permeate from the treated water chamber 1B side to the raw water chamber 1A side at a lower flow rate than in the first membrane cleaning step.

このように洗浄水が濾過膜72を透過する際の流速は、1〜3m/sが好ましい。   Thus, the flow rate when the washing water permeates the filtration membrane 72 is preferably 1 to 3 m / s.

また、この第2の膜洗浄工程において洗浄水を供給する時間は、10〜90秒が好ましい。   The time for supplying the cleaning water in the second film cleaning step is preferably 10 to 90 seconds.

これにより、洗浄水は、瞬間的に濾過膜72を通過する第1の膜洗浄工程とは異なり、濾過膜72の孔をゆっくり、じわっと通過することになる。この洗浄水は、加圧洗浄時のようにプリーツの山部(濾過方向に沿って見た場合に山となる部分)に集中することなく、プリーツ状の濾過膜72の表面のほぼ全面に対して垂直方向に通過しようとするため、プリーツの谷部(濾過方向に沿って見た場合に谷となる部分)内も洗浄水が通過して、第1の膜洗浄工程によっても除去しきれなかったプリーツの谷部に残留、蓄積したシルト等の付着物質が、緩慢に流れる洗浄水の流れによって徐々に膜表面から剥離し、洗浄水と共に原水室1A内に流出する。   Thus, unlike the first membrane cleaning step in which the cleaning water instantaneously passes through the filtration membrane 72, the cleaning water slowly and gradually passes through the pores of the filtration membrane 72. This washing water does not concentrate on the pleat crests (portions that are crested when viewed along the filtration direction) as in pressure washing, but on the almost entire surface of the pleated filtration membrane 72. Since it is going to pass in the vertical direction, the cleaning water also passes through the valley of the pleat (the part that becomes a valley when viewed along the filtration direction) and cannot be removed even by the first film cleaning process. Deposited substances such as silt remaining and accumulated in the valleys of the pleats gradually peel off from the membrane surface by the slowly flowing wash water flow and flow out into the raw water chamber 1A together with the wash water.

従って、逆洗運転においてかかる第1の膜洗浄工程の後に第2の膜洗浄工程を実施することにより、濾過膜72をシルト等の付着がない新品の膜と同等の状態に回復させることができ、膜間差圧の上昇を抑えて、長期に安定した濾過運転を行うことが可能となる。   Therefore, by performing the second membrane cleaning step after the first membrane cleaning step in the backwash operation, the filtration membrane 72 can be restored to a state equivalent to a new membrane without adhesion of silt or the like. In addition, it is possible to suppress a rise in transmembrane pressure and perform a stable filtration operation for a long time.

本発明において、第1の膜洗浄工程及び第2の膜洗浄工程は、1度の逆洗運転において複数回繰り返し行うことが好ましい。この場合、第1の膜洗浄工程と第2の膜洗浄工程とを交互に複数回繰り返す態様に限らず、第1の膜洗浄工程だけを複数回繰り返した後、第2の膜洗浄工程を実施する態様等としてもよい。   In the present invention, the first film cleaning step and the second film cleaning step are preferably repeated a plurality of times in one backwash operation. In this case, the first film cleaning process and the second film cleaning process are not limited to being alternately repeated a plurality of times, but only the first film cleaning process is repeated a plurality of times, and then the second film cleaning process is performed. It is good also as an aspect to do.

図5、図6は、同一の濾過膜を有する膜濾過装置によって海水を膜濾過した場合について、第1の膜洗浄工程のみを行った態様(図5)と、第1の膜洗浄工程の後に第2の膜洗浄工程を行った態様(図6)における膜間差圧の変化を調べたグラフである。ここでは、それぞれ膜濾過装置を2塔用意し、一方が濾過運転している間に他方を逆洗し、待機させる運転を行うようにしている。   FIG. 5 and FIG. 6 show an embodiment (FIG. 5) in which only the first membrane cleaning step is performed when seawater is membrane filtered by a membrane filtration device having the same filtration membrane, and after the first membrane cleaning step. It is the graph which investigated the change of the transmembrane differential pressure in the mode (Drawing 6) which performed the 2nd membrane washing process. Here, two towers of membrane filtration devices are prepared, and while one side is performing a filtration operation, the other is back-washed, and an operation for waiting is performed.

図5の態様では、各逆洗運転時に、500kPaの加圧空気を洗浄水で満たした処理水室に送って一気に排出する第1の膜洗浄工程のみを実施した。その結果、逆洗運転実施直後は一時的に膜間差圧が低下するが、直ぐに上昇し、累積運転時間の増加に伴って徐々に上昇しており、全体的に傾きが大きくなっている。   In the aspect of FIG. 5, only the 1st film | membrane washing | cleaning process which sends to the treated water chamber which filled the pressurized air of 500 kPa with washing water at each backwash operation, and discharges at a stretch was implemented. As a result, immediately after the backwash operation is performed, the transmembrane pressure difference temporarily decreases, but increases immediately, gradually increases with an increase in the cumulative operation time, and the overall inclination increases.

一方、図6の態様では、各逆洗運転時に、500kPaの加圧空気を洗浄水で満たした処理水室に送って一気に排出する第1の膜洗浄工程と、流速1.5m/sでの洗浄水の供給を行う第2の膜洗浄工程とを交互に繰り返した。その結果、膜間差圧は図5の態様に比べて著しく低下し、累積運転時間24時間後の膜間差圧は60%低下し、全体的に傾きは小さくなっており、図5の態様に比べて長期に亘って安定して濾過運転可能であった。   On the other hand, in the mode of FIG. 6, at the time of each backwash operation, the first membrane cleaning step of sending the pressurized air of 500 kPa to the treated water chamber filled with the cleaning water and discharging it at once, and the flow rate at 1.5 m / s The second film cleaning step of supplying cleaning water was repeated alternately. As a result, the transmembrane pressure difference is significantly reduced as compared with the embodiment of FIG. 5, the transmembrane pressure difference after 24 hours of cumulative operation is reduced by 60%, and the overall inclination is reduced. In comparison with the above, it was possible to stably perform the filtration operation for a long time.

本発明の逆洗方法を実施するのに好適な膜濾過装置の一例を示す概略断面図The schematic sectional drawing which shows an example of the membrane filtration apparatus suitable for enforcing the backwashing method of this invention 濾過筒の断面図Cross section of filter tube 濾過膜を微細気泡が通過する様子を説明する図A figure explaining how fine bubbles pass through a filtration membrane 濾過膜を微細気泡が通過する様子を説明する図A figure explaining how fine bubbles pass through a filtration membrane 第1の膜洗浄工程のみを行った場合の累積運転時間と膜間差圧との関係を示すグラフThe graph which shows the relationship between the accumulation operation time at the time of performing only a 1st film | membrane washing | cleaning process, and transmembrane differential pressure | voltage 第1の膜洗浄工程と第2の膜洗浄工程とを行った場合の累積運転時間と膜間差圧との関係を示すグラフThe graph which shows the relationship between the accumulation operation time at the time of performing a 1st film | membrane washing | cleaning process and a 2nd film | membrane washing | cleaning process, and transmembrane pressure difference 従来の逆洗後の膜表面の様子を説明する図The figure explaining the state of the film surface after the conventional backwashing

符号の説明Explanation of symbols

1:濾過槽
1A:原水室
1B:処理水室
11:仕切板
12:原水供給口
13:処理水排出口
14:洗浄排水排出口
2:原水供給管
21:開閉弁
3:処理水排出管
31:開閉弁
4:洗浄水供給管
41:開閉弁
42:洗浄水供給ポンプ
43:洗浄水タンク
5:加圧用空気供給管
51:開閉弁
52:加圧用空気供給源
53:圧力計
6:洗浄排水排出管
61:開閉弁
7:濾過筒
71:支持体
72:濾過膜
72a:孔
73:上部開口
8:微細気泡吐出部
81:空気供給管
82:空気供給源
1: Filtration tank 1A: Raw water chamber 1B: Treated water chamber 11: Partition plate 12: Raw water supply port 13: Treated water discharge port 14: Washing drain discharge port 2: Raw water supply pipe 21: On-off valve 3: Treated water discharge pipe 31 : On-off valve 4: Wash water supply pipe 41: On-off valve 42: Wash water supply pump 43: Wash water tank 5: Pressurization air supply pipe 51: On-off valve 52: Pressurization air supply source 53: Pressure gauge 6: Wash drainage Discharge pipe 61: On-off valve 7: Filter cylinder 71: Support body 72: Filtration membrane 72a: Hole 73: Upper opening 8: Fine bubble discharge part 81: Air supply pipe 82: Air supply source

Claims (6)

濾過槽内が仕切板により原水室と処理水室とに区画され、前記原水室内に、前記仕切板を貫通して前記処理水室側に開口する袋状の膜を備えた多数の濾過筒が設置され、前記原水室に入った原水が該原水室内を上向流しながら前記膜により濾過され処理水として前記濾過筒内を上昇して前記処理水室内に集水される構造を有し、前記処理水室には開閉弁を介して洗浄水供給管が接続され、前記原水室には開閉弁を介して洗浄排水排出管が接続された膜濾過装置の逆洗方法において、
前記処理水室に洗浄水を満たした状態で前記洗浄排水排出管の開閉弁を閉じ、前記処理水室内に空気を注入して洗浄水を加圧した後、前記洗浄排水排出管の開閉弁を開くことにより、加圧された洗浄水を一気に膜透過させて前記膜の逆洗浄を行う第1の膜洗浄工程と、
前記第1の膜洗浄工程の後、前記洗浄排水排出管の開閉弁を開いた状態で前記洗浄水供給管から前記処理水室に洗浄水を供給することにより、前記第1の膜洗浄工程よりも小さい流速で洗浄水を膜透過させて前記膜の逆洗浄を行う第2の膜洗浄工程とを有することを特徴とする膜濾過装置の逆洗方法。
The inside of the filtration tank is partitioned into a raw water chamber and a treated water chamber by a partition plate, and a number of filter cylinders provided with a bag-like membrane that penetrates the partition plate and opens to the treated water chamber side in the raw water chamber. The raw water that has been installed and enters the raw water chamber is filtered by the membrane while flowing upward in the raw water chamber, and has a structure in which the raw water rises in the filter cylinder as treated water and is collected in the treated water chamber, In the backwashing method of the membrane filtration apparatus, the cleaning water supply pipe is connected to the treated water chamber via an on-off valve, and the cleaning water discharge pipe is connected to the raw water chamber via the on-off valve.
After the treatment water chamber is filled with washing water, the on-off valve of the washing drainage pipe is closed, air is injected into the treatment water chamber to pressurize the washing water, and then the on-off valve of the washing drainage discharge pipe is opened. A first membrane cleaning step for performing reverse cleaning of the membrane by opening the pressurized cleaning water through the membrane at a stretch by opening,
After the first membrane cleaning step, by supplying cleaning water from the cleaning water supply pipe to the treated water chamber with the opening / closing valve of the cleaning drainage pipe opened, the first membrane cleaning step And a second membrane cleaning step of performing reverse cleaning of the membrane by allowing the cleaning water to pass through the membrane at a low flow rate.
前記第2の膜洗浄工程における前記洗浄水の流速は、1〜3m/sであることを特徴とする請求項1記載の膜濾過装置の逆洗方法。   The backwashing method for a membrane filtration device according to claim 1, wherein a flow rate of the washing water in the second membrane washing step is 1 to 3 m / s. 前記第2の膜洗浄工程における前記洗浄水の供給時間は、10〜90秒であることを特徴とする請求項1又は2記載の膜濾過装置の逆洗方法。   The backwashing method for a membrane filtration device according to claim 1 or 2, wherein the cleaning water supply time in the second membrane cleaning step is 10 to 90 seconds. 前記膜は、プリーツ状の膜であることを特徴とする請求項1、2又は3記載の膜濾過装置の逆洗方法。   4. The method for backwashing a membrane filtration device according to claim 1, wherein the membrane is a pleated membrane. 前記第1の膜洗浄工程において、前記処理水室内の洗浄水中に微細気泡を導入することを特徴とする請求項1〜4のいずれかに記載の膜濾過装置の逆洗方法。   The backwashing method for a membrane filtration device according to any one of claims 1 to 4, wherein in the first membrane cleaning step, fine bubbles are introduced into the cleaning water in the treated water chamber. 前記原水は船舶のバラストタンクに供給するためのバラスト水であることを特徴とする請求項1〜5のいずれかに記載の膜濾過装置の逆洗方法。   The method for backwashing a membrane filtration device according to any one of claims 1 to 5, wherein the raw water is ballast water to be supplied to a ballast tank of a ship.
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012206025A (en) * 2011-03-30 2012-10-25 Panasonic Corp Device for producing ballast water, and method for operating the same
KR101402201B1 (en) 2011-12-23 2014-05-30 (주)필로스 Back washing apparatus of membrane
CZ305501B6 (en) * 2010-08-24 2015-11-04 Vysoká škola chemicko-technologická v Praze, Ústav chemie a technologie sacharidů Device for backward rinsing of separation membranes in a membrane module
CN116332255A (en) * 2023-04-10 2023-06-27 长沙捷尔美环卫机械设备有限公司 Sanitation car water circulating system

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CZ305501B6 (en) * 2010-08-24 2015-11-04 Vysoká škola chemicko-technologická v Praze, Ústav chemie a technologie sacharidů Device for backward rinsing of separation membranes in a membrane module
JP2012206025A (en) * 2011-03-30 2012-10-25 Panasonic Corp Device for producing ballast water, and method for operating the same
KR101402201B1 (en) 2011-12-23 2014-05-30 (주)필로스 Back washing apparatus of membrane
CN116332255A (en) * 2023-04-10 2023-06-27 长沙捷尔美环卫机械设备有限公司 Sanitation car water circulating system
CN116332255B (en) * 2023-04-10 2024-04-23 长沙捷尔美环卫机械设备有限公司 Sanitation car water circulating system

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