JP2016016397A - Filtration membrane cleaning method and membrane filtration apparatus - Google Patents
Filtration membrane cleaning method and membrane filtration apparatus Download PDFInfo
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- Separation Using Semi-Permeable Membranes (AREA)
Abstract
Description
本発明は、原水から濁質及び有機物を除去する膜ろ過装置及び当該膜ろ過装置に組み込まれているろ過膜の洗浄方法に関し、特に海水又は汽水を脱塩して淡水化する膜ろ過装置及びろ過膜洗浄方法に関する。 The present invention relates to a membrane filtration device for removing turbidity and organic substances from raw water and a method for cleaning a filtration membrane incorporated in the membrane filtration device, and more particularly, a membrane filtration device for desalting seawater or brackish water to make it desalinated and filtration The present invention relates to a film cleaning method.
従来、海水或いは汽水を脱塩して、工業用水或いは飲用水を得る場合の脱塩方法として、逆浸透膜（ＲＯ：reverse osmosis membrane）法、電気透析法又は電気式脱塩法、蒸発法などがあり広く知られている。これらの技術を採用する場合には、予め海水或いは汽水に含まれている濁質を除去する前処理が必要であり、凝集法、砂ろ過法、加圧浮上法、ＭＦ（micro filtration membrane）／ＵＦ（ultra filtration membrane）膜法などが単独又は併用して使用されていた。 Conventionally, as a desalting method when desalting seawater or brackish water to obtain industrial water or drinking water, a reverse osmosis membrane (RO) method, an electrodialysis method or an electrical desalting method, an evaporation method, etc. Is widely known. When these technologies are adopted, pretreatment for removing turbidity contained in seawater or brackish water is required in advance, such as agglomeration method, sand filtration method, pressurized flotation method, MF (micro filtration membrane) / A UF (ultra filtration membrane) membrane method or the like has been used alone or in combination.
昨今、海水或いは汽水に流入する都市下水などの影響により、濁質のみならず、液中に溶解している有機物が、ＲＯ膜法、電気透析法、電気式脱塩法、蒸発法の運転において、メンテナンス及びコストに大きな影響を与えることが顕在化してきた。特に、前述したＭＦ膜、ＵＦ膜、ＲＯ膜などの膜を用いる脱塩法では、膜表面に溶解している有機物や濁質が蓄積してファウリング（目詰まり、閉塞など）を引き起こし、膜流速の低下、逆洗頻度の増加、膜寿命の減少などが発生する問題があった。 Recently, due to the influence of municipal sewage flowing into seawater or brackish water, not only turbidity but also organic matter dissolved in the liquid is used in the operation of RO membrane method, electrodialysis method, electric desalination method, evaporation method. It has become apparent that it has a significant impact on maintenance and cost. In particular, in the desalting method using a membrane such as the above-mentioned MF membrane, UF membrane, RO membrane, etc., organic matter and turbidity dissolved on the membrane surface accumulate and cause fouling (clogging, blockage, etc.). There have been problems such as a decrease in flow rate, an increase in backwash frequency, and a decrease in membrane life.
そこで、近年、逆浸透膜（ＲＯ）装置の前段に、原水中の濁質分をろ過する前処理膜を有する前処理装置を設ける淡水化装置が提案されている。例えば、前処理膜として、限外濾過膜（ＵＦ）又は精密ろ過膜（ＭＦ）等の分離膜を用いることが記載されている（特許文献１）。しかし、この淡水化装置及びその洗浄方法においては、逆洗や淡水加熱を適用することによりスケール除去するものであるが、十分な洗浄ができず、また長期的、効率的に、安定してろ過膜を洗浄することは困難であった。 Thus, in recent years, a desalination apparatus has been proposed in which a pretreatment device having a pretreatment membrane for filtering turbid components in raw water is provided in the previous stage of a reverse osmosis membrane (RO) device. For example, it is described that a separation membrane such as an ultrafiltration membrane (UF) or a microfiltration membrane (MF) is used as a pretreatment membrane (Patent Document 1). However, in this desalination apparatus and its washing method, the scale is removed by applying backwashing or freshwater heating, but sufficient washing cannot be performed, and long-term, efficient, and stable filtration. It was difficult to clean the membrane.
また、中空糸膜モジュールの洗浄方法において、ろ過水を膜のろ過水側から原水側へ通過させてろ過水側を洗浄する逆洗浄と、粒径１００μｍ以下の微細気泡を含む液体を原水側に導入し、膜の原水側表面の洗浄を行う微細気泡洗浄と、モジュール下部より膜の原水側に粗大気泡を導入して膜を揺動させて膜の原水側表面の洗浄を行うエアバブリングとを、この洗浄順序で行う洗浄方法が提案されている（特許文献２）。この中空糸膜モジュールの洗浄方法は、透過水側からの逆洗浄、原水側からの微細気泡洗浄、及び原水側からのエアバブリングを順次行う必要があり、操作が煩雑で手間と時間がかかり、洗浄効果には限界があった。 Moreover, in the washing method of the hollow fiber membrane module, reverse washing in which filtered water is passed from the filtered water side of the membrane to the raw water side to wash the filtered water side, and a liquid containing fine bubbles having a particle size of 100 μm or less is brought to the raw water side. Microbubble cleaning that introduces and cleans the raw water side surface of the membrane, and air bubbling that cleans the raw water side surface of the membrane by introducing coarse bubbles from the bottom of the module to the raw water side of the membrane and swinging the membrane A cleaning method performed in this cleaning order has been proposed (Patent Document 2). This method of cleaning the hollow fiber membrane module requires the back washing from the permeate side, the fine bubble washing from the raw water side, and the air bubbling from the raw water side in order, and the operation is complicated and takes time and effort. There was a limit to the cleaning effect.
更に、ＵＦ又はＭＦ膜モジュールを用いた水浄化システムにおいて、原水が、ＵＦ又はＭＦ膜モジュールに流入される前に、超微細気泡を原水中に混合させつつ、膜ろ過を行う過方法が提案されている（特許文献３）。このＵＦ又はＭＦ膜モジュールを用いた水浄化システムでは、原水が濾過膜モジュールに流入する前に超微細気泡を原水中に混合させて膜濾過する方法であるが、超微細気泡発生装置は、環状スリットを有する特殊な装置であり、汎用の微細気泡発生装置を用いることはできず、定められた洗浄手順で行わなければならない、という制約がある。 Furthermore, in a water purification system using a UF or MF membrane module, an over method is proposed in which membrane filtration is performed while mixing ultrafine bubbles into the raw water before the raw water flows into the UF or MF membrane module. (Patent Document 3). This water purification system using a UF or MF membrane module is a method in which ultrafine bubbles are mixed into the raw water and filtered before the raw water flows into the filtration membrane module. This is a special device having a slit, and a general-purpose fine bubble generating device cannot be used, and there is a restriction that it must be performed by a predetermined cleaning procedure.
本発明は、長期的、効率的に、安定してろ過膜を稼働させることができる膜ろ過装置及びろ過膜洗浄方法を提供することを目的とする。 An object of the present invention is to provide a membrane filtration apparatus and a filtration membrane cleaning method capable of operating a filtration membrane stably over a long period of time and efficiently.
特に、簡易な操作で、短時間で、良好な洗浄効果を発揮することができる上記膜ろ過装置及びろ過膜洗浄方法を提供することを目的とする。 In particular, it is an object of the present invention to provide the membrane filtration apparatus and the filtration membrane cleaning method that can exhibit a good cleaning effect in a short time with a simple operation.
本発明者らは、ろ過膜の透過水側から原水側へろ過膜透過水を逆洗浄水として通水する逆洗浄工程と、ろ過膜の原水側に微細気泡を含む洗浄水を導入して上向流として流す微細気泡洗浄工程と、を同時に行うことで、ろ過膜の洗浄効率を向上させることができることを見出して本発明を完成するに至った。本発明の具体的態様は以下のとおりである。
［１］原水中の少なくとも溶解性有機物又は濁質分を含む汚染物を除去して膜ろ過透過水を得るろ過膜と、ろ過膜の原水側に位置づけられている原水入口と、ろ過膜の透過水側に位置づけられている膜ろ過透過水出口と、ろ過膜モジュールの底部に設けられている洗浄水導入口と、ろ過膜モジュールの上部に設けられている洗浄排水出口と、を具備するろ過膜モジュールの洗浄方法であって、
以下の２工程：
（１）当該ろ過膜の透過水側から原水側へ、当該ろ過膜透過水を逆洗浄水として通水する逆洗浄工程；及び
（２）当該洗浄水導入口より当該ろ過膜の原水側に微細気泡混入洗浄水を当該ろ過膜に沿って流し、当該洗浄排水出口から排出する微細気泡洗浄工程
を同時に行うことを特徴とする洗浄方法。
［２］前記（２）微細気泡洗浄工程に用いる微細気泡混入洗浄水として、前記ろ過膜モジュールの洗浄排水出口から排出される洗浄排水の少なくとも一部を再利用し、微細気泡を混入させてなる微細気泡混入洗浄排水を用いることを特徴とする、［１］に記載の洗浄方法。
［３］前記ろ過膜モジュールの下流側にさらに逆浸透膜モジュールを具備し、
前記（１）逆洗浄工程に用いる逆洗浄水として、前記ろ過膜透過水をさらに逆浸透膜モジュールに通水して塩類を除去した後の逆浸透膜透過水を用いることを特徴とする、［１］又は［２］に記載の洗浄方法。
［４］前記ろ過膜モジュールの下流側にさらに逆浸透膜モジュールを具備し、
前記（２）微細気泡洗浄工程に用いる微細気泡混入洗浄水として、前記ろ過膜透過水をさらに逆浸透膜モジュールに通水して塩類を除去した後の逆浸透膜透過水を再利用し、微細気泡を混入させてなる微細気泡混入逆浸透膜透過水を用いることを特徴とする、［１］〜［３］のいずれかに記載の洗浄方法。
［５］前記（１）逆洗浄工程において用いる逆洗浄水は、塩酸、硫酸、硝酸、シュウ酸、クエン酸、アスコルビン酸、過酸化水素、水酸化ナトリウム、次亜塩素酸ナトリウム、キレート剤、界面活性剤および酵素のうち少なくとも１種又は２種以上を含むことを特徴とする［１］〜［４］のいずれかに記載の洗浄方法。
［６］原水中の少なくとも溶解性有機物又は濁質分を含む汚染物を除去して膜ろ過透過水を得るろ過膜と、ろ過膜の原水側に位置づけられている原水入口と、ろ過膜の透過水側に位置づけられている膜ろ過透過水出口と、ろ過膜モジュールの底部に設けられている洗浄水導入口と、ろ過膜モジュールの上部に設けられている洗浄排水出口と、を具備するろ過膜モジュールと、
膜ろ過後の透過水を逆洗浄水として当該ろ過膜モジュールのろ過膜の透過水側に返送する逆洗浄水ラインと、
微細気泡混入洗浄水を当該ろ過膜モジュールの洗浄水導入口に送液する微細気泡混入洗浄水導入管と、
当該微細気泡混入洗浄水を生成する微細気泡発生装置と、
当該ろ過膜モジュールのろ過膜の以下の２つの洗浄工程：
（１）当該ろ過膜の透過水側から原水側へ、当該ろ過膜透過水を逆洗浄水として通水する逆洗浄工程；及び
（２）当該洗浄水導入口より当該ろ過膜の原水側に微細気泡混入洗浄水を当該ろ過膜に沿って流し、当該洗浄排水出口から排出する微細気泡洗浄工程
を同時に行う制御部と、を具備することを特徴とする膜ろ過装置。
［７］前記ろ過膜モジュールからの膜ろ過透過水から塩類を除去する逆浸透膜装置をさらに具備し、
前記逆洗浄水ラインは、当該逆浸透膜装置からの透過水を当該ろ過膜モジュールの透過水側に返送することを特徴とする［６］に記載の膜ろ過装置。
［８］前記ろ過膜モジュールからの膜ろ過透過水から塩類を除去する逆浸透膜装置をさらに具備し、
当該逆浸透膜装置からの透過水の一部を前記微細気泡発生装置に送液する透過水送水管を具備することを特徴とする［６］又は［７］に記載の膜ろ過装置。
［９］前記ろ過膜モジュールからの洗浄排水を前記微細気泡発生装置に送液する洗浄排水送液管をさらに具備することを特徴とする［６］〜［８］のいずれかに記載の膜ろ過装置。
［１０］前記ろ過膜モジュール底部に、ろ過モジュール内の微細気泡混入洗浄水中に粗大気泡を発生させるためのエア入口が設けられていることを特徴とする［６］〜［９］の何れかに記載の膜ろ過装置。
［１１］前記ろ過膜モジュールは、円筒状のモジュールであることを特徴とする［６］〜［１０］の何れかに記載の膜ろ過装置。
The present inventors introduced a reverse cleaning step of passing the filtration membrane permeate as backwash water from the permeate side of the filtration membrane to the raw water side, and introduced wash water containing fine bubbles on the raw water side of the filtration membrane. It has been found that the cleaning efficiency of the filtration membrane can be improved by simultaneously performing the fine bubble cleaning step that flows as a countercurrent, and the present invention has been completed. Specific embodiments of the present invention are as follows.
[1] A filtration membrane that obtains membrane filtration permeated water by removing contaminants including at least soluble organic substances or turbid components in the raw water, a raw water inlet positioned on the raw water side of the filtration membrane, and permeation of the filtration membrane A filtration membrane comprising a membrane filtration permeate outlet positioned on the water side, a washing water inlet provided at the bottom of the filtration membrane module, and a washing drain outlet provided at the top of the filtration membrane module A module cleaning method,
The following two steps:
(1) a reverse washing step of passing the filtered membrane permeate as backwash water from the permeate side of the filter membrane to the raw water side; and (2) fine from the wash water inlet to the raw water side of the filter membrane. A cleaning method characterized by simultaneously performing a fine bubble cleaning step of flowing bubble-containing cleaning water along the filtration membrane and discharging the cleaning water from the cleaning drain outlet.
[2] (2) As the fine bubble mixed cleaning water used in the fine bubble cleaning step, at least a part of the cleaning wastewater discharged from the cleaning drain outlet of the filtration membrane module is reused to mix fine bubbles. The cleaning method according to [1], wherein cleaning water containing fine bubbles is used.
[3] A reverse osmosis membrane module is further provided on the downstream side of the filtration membrane module,
The reverse osmosis membrane permeated water after removing the salts by further passing the filtered membrane permeated water through a reverse osmosis membrane module as the backwash water used in the (1) reverse washing step, The cleaning method according to [1] or [2].
[4] A reverse osmosis membrane module is further provided on the downstream side of the filtration membrane module,
(2) As the fine bubble mixed washing water used in the fine bubble washing step, the filtration membrane permeated water is further passed through a reverse osmosis membrane module to remove salts, and the reverse osmosis membrane permeated water is reused. The cleaning method according to any one of [1] to [3], wherein permeated water containing fine bubbles mixed with bubbles is used.
[5] The backwashing water used in the (1) backwashing step is hydrochloric acid, sulfuric acid, nitric acid, oxalic acid, citric acid, ascorbic acid, hydrogen peroxide, sodium hydroxide, sodium hypochlorite, chelating agent, interface The cleaning method according to any one of [1] to [4], comprising at least one or more of an activator and an enzyme.
[6] A filtration membrane that obtains membrane filtration permeated water by removing contaminants including at least soluble organic matter or turbid components in the raw water, a raw water inlet positioned on the raw water side of the filtration membrane, and permeation of the filtration membrane A filtration membrane comprising a membrane filtration permeate outlet positioned on the water side, a washing water inlet provided at the bottom of the filtration membrane module, and a washing drain outlet provided at the top of the filtration membrane module Module,
Backwash water line for returning the permeated water after membrane filtration to the permeated water side of the filtration membrane of the filtration membrane module as backwash water;
A fine bubble-containing cleaning water introduction pipe for sending the fine bubble-containing cleaning water to the cleaning water inlet of the filtration membrane module;
A fine bubble generating device for generating the fine bubble mixed cleaning water;
The following two washing steps for the membrane of the membrane module:
(1) a reverse washing step of passing the filtered membrane permeate as backwash water from the permeate side of the filter membrane to the raw water side; and (2) fine from the wash water inlet to the raw water side of the filter membrane. A membrane filtration apparatus comprising: a control unit that simultaneously performs a fine bubble washing step of causing bubble-containing washing water to flow along the filtration membrane and discharging it from the washing drain outlet.
[7] The apparatus further comprises a reverse osmosis membrane device for removing salts from the membrane filtration permeated water from the filtration membrane module,
The reverse filtration water line returns the permeated water from the reverse osmosis membrane device to the permeate side of the filtration membrane module, [6].
[8] Further comprising a reverse osmosis membrane device for removing salts from the membrane filtration permeated water from the filtration membrane module,
The membrane filtration device according to [6] or [7], further comprising a permeate water feeding pipe for feeding a part of permeate from the reverse osmosis membrane device to the fine bubble generator.
[9] The membrane filtration according to any one of [6] to [8], further comprising a washing wastewater feeding pipe for feeding the washing wastewater from the filtration membrane module to the fine bubble generator. apparatus.
[10] Any one of [6] to [9], wherein an air inlet is provided at the bottom of the filtration membrane module for generating coarse bubbles in the washing water containing fine bubbles in the filtration module. The membrane filtration apparatus described.
[11] The membrane filtration device according to any one of [6] to [10], wherein the filtration membrane module is a cylindrical module.
本発明によれば、長期的、効率的に、安定してろ過膜を稼働させることができるろ過膜装置及びろ過膜洗浄方法が提供される。 ADVANTAGE OF THE INVENTION According to this invention, the filtration membrane apparatus and the filtration membrane washing | cleaning method which can operate a filtration membrane stably for a long term and efficiently are provided.
特に、簡易な操作で、短時間で、良好な洗浄効果を発揮することができる上記ろ過膜装置及びろ過膜洗浄方法が提供される。 In particular, the filtration membrane device and the filtration membrane cleaning method capable of exhibiting a good cleaning effect with a simple operation in a short time are provided.
以下、添付図面を参照しながら本発明をさらに詳細に説明するが、本発明はこれらに限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings, but the present invention is not limited thereto.
図１Ａはろ過膜モジュールを組み入れた膜ろ過装置の概略説明図であり、図１Ｂはろ過膜モジュールの拡大断面図である。 FIG. 1A is a schematic explanatory view of a membrane filtration apparatus incorporating a filtration membrane module, and FIG. 1B is an enlarged sectional view of the filtration membrane module.
原水中の溶解性有機物及び濁質分を除去して膜ろ過透過水を得るろ過膜１０を内蔵するろ過膜モジュールの底部には、ろ過膜１０の原水側１０ａに原水入口１０ｃ及び洗浄水導入口１０ｅが設けられ、ろ過膜モジュールの上部には、ろ過膜１０の原水側に洗浄排水出口１０ｆ、ろ過膜１０の透過水側１０ｂに透過水出口１０ｄが設けられている。 At the bottom of the filtration membrane module containing the filtration membrane 10 that removes soluble organic substances and turbid components from the raw water to obtain membrane filtration permeated water, the raw water inlet 10c and the washing water inlet are connected to the raw water side 10a of the filtration membrane 10. 10e is provided, and in the upper part of the filtration membrane module, a washing drainage outlet 10f is provided on the raw water side of the filtration membrane 10, and a permeate outlet 10d is provided on the permeate side 10b of the filtration membrane 10.
原水入口１０ｃには原水供給管１３、透過水出口１０ｄには透過水配管１７、洗浄水導入口１０ｅには洗浄水導入管１６、洗浄排水出口１０ｆには洗浄排水管１１が、それぞれ接続されている。透過水配管１７には、後述する逆洗浄ライン２２が接続され、逆洗浄ライン２２の接続部位には弁Ｖ１が設けられており、ろ過膜モジュールからろ過水槽２０へ透過水を送液するか又は逆洗浄ライン２２からの逆洗浄水をろ過膜モジュールに流入させるかの切り替えを行う。 A raw water supply pipe 13 is connected to the raw water inlet 10c, a permeate pipe 17 is connected to the permeate outlet 10d, a wash water introduction pipe 16 is connected to the wash water inlet 10e, and a wash drain pipe 11 is connected to the wash drain outlet 10f. Yes. A reverse cleaning line 22 to be described later is connected to the permeated water pipe 17, and a valve V <b> 1 is provided at a connection portion of the reverse cleaning line 22, and the permeated water is sent from the filtration membrane module to the filtered water tank 20 or Switching between backwash water from the backwash line 22 and flowing into the membrane filter module is performed.
透過水配管１７は、透過水を貯留するろ過水槽２０に接続されている。ろ過水槽２０には、透過水を逆洗浄水としてろ過膜モジュールに返送する逆洗浄ライン２２が接続されている。逆洗浄ライン２２には、途中で洗浄薬剤を投入する薬剤投入ライン２７が接続されている。逆洗浄ライン２２は、透過水配管１７に接続され、弁Ｖ１の切り替えによりろ過膜モジュールに逆洗浄水を供給する。尚、ろ過水槽２０は省略することもできる。この場合には、逆洗浄ライン２２がろ過水槽を兼務する。 The permeated water pipe 17 is connected to a filtered water tank 20 that stores permeated water. Connected to the filtered water tank 20 is a reverse cleaning line 22 for returning the permeated water as reverse cleaning water to the filtration membrane module. The reverse cleaning line 22 is connected to a chemical charging line 27 for charging a cleaning chemical on the way. The reverse cleaning line 22 is connected to the permeated water pipe 17 and supplies the reverse cleaning water to the filtration membrane module by switching the valve V1. In addition, the filtration water tank 20 can also be abbreviate | omitted. In this case, the backwash line 22 also serves as a filtered water tank.
ろ過膜モジュールの洗浄水導入口１０ｅには、微細気泡発生装置１５からの微細気泡混入洗浄水を供給する微細気泡混入洗浄水導入管１６が接続されている。微細気泡発生装置１５には、洗浄水を導入する洗浄水導入管１８が接続されている。微細気泡発生装置１５に導入された洗浄水に微細気泡が混入され、微細気泡混入洗浄水が生成される。 Connected to the cleaning water introduction port 10e of the filtration membrane module is a fine bubble mixed cleaning water introduction pipe 16 for supplying the fine bubble mixed cleaning water from the fine bubble generating device 15. A washing water introduction pipe 18 for introducing washing water is connected to the fine bubble generating device 15. Fine bubbles are mixed into the washing water introduced into the fine bubble generating device 15 to generate washing water containing fine bubbles.
図１Ｂに示すように、ろ過膜モジュールの中央部には、ろ過膜１０が位置づけられ、原水はろ過膜の周囲の原水側１０ａに供給される。ろ過膜１０で原水から溶解性有機物又は濁質分などの汚染物が除去される。これらの汚染物が除去された透過水は、ろ過膜１０の透過水側１０ｂに透過して、透過水出口１０ｄから排出される。 As shown in FIG. 1B, the filtration membrane 10 is positioned at the center of the filtration membrane module, and the raw water is supplied to the raw water side 10a around the filtration membrane. Filter membrane 10 removes contaminants such as soluble organic matter or turbid matter from raw water. The permeated water from which these contaminants have been removed passes through the permeate side 10b of the filtration membrane 10 and is discharged from the permeate outlet 10d.
ろ過膜１０の洗浄時には、透過水出口１０ｄから逆洗浄水が導入され、ろ過膜１０の透過水側１０ｂから原水側１０ａに逆洗浄水が透過し、ろ過膜１０の膜面に付着している溶解性有機物又は濁質分などの汚染物を剥離させる。同時に、ろ過膜モジュール底部の洗浄水導入口１０ｅから微細気泡混入洗浄水が導入され、ろ過膜１０に沿って上向流としてろ過膜モジュール内を流通して、ろ過膜モジュール上部の洗浄排水出口１０ｆから排出される。微細気泡混入洗浄水は、直径１μｍ以下のナノバブル及び１μｍ〜５０μｍ程度のマイクロバブルを混入させた洗浄水である。微細気泡の表面はＯＨ−、Ｃｌ−、ＣＯＯ−が濃縮することでマイナスにチャージしており、帯電性を有しているため、溶解性有機物を構成するヒドロキシル基やカルボキシル基、タンパク質など水素結合によってろ過膜の膜面に付着している汚染物を、電気的中和あるいは反発、若しくはろ過膜表面でのイオン交換的な作用を利用して剥離することができる。微細気泡混入洗浄水は、微細気泡がろ過膜１０の膜面に付着している汚染物の内部及び膜面と汚染物との間に入り込み、微細気泡による電気的中和力、電気的反発力、イオン交換作用、微細気泡が崩壊する際の圧力や温度変化などの物理的な作用等によって、汚染物をろ過膜１０の膜面から剥離させ、汚染物を随伴しながら上昇する。 When the filtration membrane 10 is washed, backwash water is introduced from the permeate outlet 10d, and the backwash water permeates from the permeate side 10b of the filter membrane 10 to the raw water side 10a and adheres to the membrane surface of the filter membrane 10. Remove contaminants such as soluble organic matter or turbidity. At the same time, fine bubble-mixed cleaning water is introduced from the cleaning water inlet 10e at the bottom of the filtration membrane module, circulates in the filtration membrane module as an upward flow along the filtration membrane 10, and the washing drain outlet 10f at the top of the filtration membrane module Discharged from. The cleaning water mixed with fine bubbles is cleaning water in which nanobubbles having a diameter of 1 μm or less and microbubbles of about 1 μm to 50 μm are mixed. Surface of the fine bubbles OH -, Cl -, COO - and charged negatively by the concentration, since it has a chargeability, hydroxyl group or carboxyl group constituting the soluble organic substances, proteins such as hydrogen bond Thus, contaminants adhering to the membrane surface of the filtration membrane can be peeled off by utilizing electrical neutralization or repulsion, or ion exchange action on the filtration membrane surface. The cleaning water mixed with fine bubbles enters the inside of contaminants between the membrane surface of the filtration membrane 10 and between the membrane surface and the contaminants, and the electric neutralization force and the electric repulsion force due to the fine bubbles. The contaminants are peeled off from the membrane surface of the filtration membrane 10 by an ion exchange action, a physical action such as a change in pressure and temperature when the fine bubbles are collapsed, and the contaminants rise while accompanying the contaminants.
本発明において、ろ過膜１０の透過水側１０ｂから原水側１０ａへの逆洗浄水の通水により、ろ過膜１０の膜面に付着している汚染物を押し出す。同時に、ろ過膜１０の透過水側１０ｂから原水側１０ａに通水される逆洗浄水により押し出されて剥離したろ過膜１０の膜面に付着していた汚染物内部に、微細気泡混入洗浄水からの微細気泡が入り込み、汚染物はろ過膜の膜面から離脱しやすくなる。また、ろ過膜１０の表面に沿って上向流として流れる微細気泡混入洗浄水がろ過膜１０の膜面に付着している汚染物を離脱させることにより、ろ過膜１０の透過水側１０ｂから原水側１０ａへの逆洗浄水の押圧によってろ過膜１０の膜面に付着している汚染物が押し出されやすくなる。すなわち、微細気泡混入洗浄水をろ過膜１０の原水側１０ａ表面に沿って通水すると同時に、逆洗浄水をろ過膜１０の透過水側１０ｂから原水側１０ａへと通水することによって、ろ過膜１０の原水側１０ａ表面に沿った流水速度が増加し、ろ過膜１０の原水側１０表面における汚染物剥離効果と透過水側１０ｂからの押圧効果とが相互に効果を助長して相乗的に作用し、ろ過膜１０の膜面から汚染物を確実に除去することができる。 In the present invention, contaminants adhering to the membrane surface of the filtration membrane 10 are pushed out by passing backwash water from the permeate side 10b of the filtration membrane 10 to the raw water side 10a. At the same time, the fine bubbles mixed in the cleaning water adhering to the membrane surface of the filtration membrane 10 that has been pushed and peeled off by the reverse washing water passed from the permeate side 10b of the filtration membrane 10 to the raw water side 10a. The fine bubbles enter, and the contaminants are easily separated from the membrane surface of the filtration membrane. Moreover, the fine water-containing cleaning water flowing as an upward flow along the surface of the filtration membrane 10 separates contaminants adhering to the membrane surface of the filtration membrane 10, thereby allowing the raw water from the permeate side 10 b of the filtration membrane 10. Contaminant adhering to the membrane surface of the filtration membrane 10 is easily pushed out by pressing the reverse washing water to the side 10a. That is, the filtration membrane is obtained by passing the washing water containing fine bubbles along the surface of the raw water side 10a of the filtration membrane 10 and simultaneously passing the reverse washing water from the permeate side 10b of the filtration membrane 10 to the raw water side 10a. The flow velocity along the surface of the raw water side 10a of 10 increases, and the contaminant peeling effect on the surface of the raw water side 10 of the filtration membrane 10 and the pressing effect from the permeate side 10b promote each other and act synergistically. In addition, contaminants can be reliably removed from the membrane surface of the filtration membrane 10.
微細気泡混入洗浄水に含まれる微細気泡は、洗浄すべき汚染物や原水の性状によっても異なり、任意の設計条件とすることができるが、一般的に気液比で０．１〜１０：１であることが好ましい。 The fine bubbles contained in the cleaning water mixed with fine bubbles vary depending on the contaminants to be cleaned and the properties of the raw water, and can be set to arbitrary design conditions. It is preferable that
微細気泡混入洗浄水の流速は、任意の流速をとることができるが、０．１〜５ｍ／ｍｉｎが好ましい。 The flow rate of the cleaning water containing fine bubbles can be any flow rate, but is preferably 0.1 to 5 m / min.
また、微細気泡に加えて、別のラインから粗大気泡を混入させて、ろ過膜面に物理的振動を与えてもよい。粗大気泡とは、微細気泡よりも大きな気泡であり、典型的には５０μｍ以上の気泡である。粗大気泡は、ろ過膜モジュール下部のエア入口１２から圧縮空気を導入することによって、微細気泡混入洗浄水中に発生させることができる。粗大気泡の混入割合は、任意の割合を取ることができ、通常の膜洗浄で使用している１〜５ｍ／ｍｉｎが好ましい。 Further, in addition to fine bubbles, coarse bubbles may be mixed from another line to give physical vibration to the filtration membrane surface. A coarse bubble is a bubble larger than a fine bubble, and is typically a bubble of 50 μm or more. Coarse bubbles can be generated in the cleaning water containing fine bubbles by introducing compressed air from the air inlet 12 below the filtration membrane module. The mixing ratio of coarse bubbles can be any ratio, and is preferably 1 to 5 m / min used in normal film cleaning.
逆洗浄工程と微細気泡洗浄工程とを同時に行う洗浄は、２０〜１２０分に１回の割合で周期的に繰り返し行う。また、逆洗浄工程と微細気泡洗浄工程は、１０〜１８０秒間、好ましくは２０〜６０秒間、行う。 The cleaning in which the reverse cleaning process and the fine bubble cleaning process are performed simultaneously is periodically repeated at a rate of once every 20 to 120 minutes. Further, the reverse cleaning step and the fine bubble cleaning step are performed for 10 to 180 seconds, preferably 20 to 60 seconds.
図２は、ろ過膜モジュールの下流側に逆浸透膜モジュール３０を設けた膜ろ過装置の一態様を示す概略説明図である。図１と同様の構成要素には同じ符号を付して説明を割愛する。 FIG. 2 is a schematic explanatory view showing an embodiment of a membrane filtration device in which a reverse osmosis membrane module 30 is provided on the downstream side of the filtration membrane module. Constituent elements similar to those in FIG.
図２において、逆浸透膜モジュール３０は、ろ過水槽２０からの透過水を受け取り、塩類を除去して処理水とする。図２は、逆浸透膜モジュール３０にて膜分離された処理水を逆洗浄水及び微細気泡混入洗浄水として再利用する態様を示す。逆浸透膜モジュール３０からの処理水は、透過水送水管５０を介して逆洗浄水としてろ過膜モジュールに返送する逆洗浄水ライン２２及び微細気泡発生装置１５に送液する洗浄水導入管１８ａに送られる。 In FIG. 2, the reverse osmosis membrane module 30 receives the permeated water from the filtered water tank 20 and removes salts to obtain treated water. FIG. 2 shows an aspect in which the treated water separated by the reverse osmosis membrane module 30 is reused as reverse washing water and washing water containing fine bubbles. The treated water from the reverse osmosis membrane module 30 passes through the permeated water feed pipe 50 to the backwash water line 22 that returns to the filtration membrane module as backwash water and the wash water introduction pipe 18a that feeds the fine bubble generator 15. Sent.
逆浸透膜モジュール３０としては、きわめて高い脱塩率が得られる半透性の膜であって、素材としては、酢酸セルロース系ポリマー、ポリアミド、ポリエステル、ポリイミド、ビニルポリマーなどが使用される。 The reverse osmosis membrane module 30 is a semipermeable membrane that can obtain a very high desalination rate, and as the material, cellulose acetate polymer, polyamide, polyester, polyimide, vinyl polymer, or the like is used.
図３は、ろ過膜モジュールからの洗浄排水を微細気泡混入洗浄水として再利用する態様を示す概略説明図である。図１及び図２と同様の構成要素には同じ符号を付して説明を割愛する。 FIG. 3 is a schematic explanatory view showing an aspect in which the cleaning waste water from the filtration membrane module is reused as cleaning water mixed with fine bubbles. The same components as those in FIGS. 1 and 2 are denoted by the same reference numerals and description thereof is omitted.
図３において、洗浄排水管１１に、洗浄排水返送管１８ｂが接続され、洗浄排水の一部が微細気泡発生装置１５に送られる。微細気泡混入洗浄水は、１μｍ以下のいわゆるナノバブルも含んでいる。マイクロバブルよりも小さなナノバブルは安定であり液中に長時間滞留できるため、使用済みの微細気泡混入洗浄排水には未使用のナノバブルが残留している。このようなナノバブルが残留している洗浄排水を再利用することによって、微細気泡混入洗浄水中のナノバブルを増やすことができ、更に洗浄効果を向上させることができると共に、洗浄水の使用量を削減することができる。 In FIG. 3, a cleaning drain return pipe 18 b is connected to the cleaning drain pipe 11, and a part of the cleaning drain is sent to the fine bubble generating device 15. The cleaning water containing fine bubbles also includes so-called nano bubbles of 1 μm or less. Since nanobubbles smaller than microbubbles are stable and can stay in the liquid for a long time, unused nanobubbles remain in the used fine bubble mixed cleaning waste water. By reusing cleaning wastewater in which such nanobubbles remain, the number of nanobubbles in the cleaning water containing fine bubbles can be increased, the cleaning effect can be further improved, and the amount of cleaning water used can be reduced. be able to.
図４は、逆浸透モジュール３０を具備する膜ろ過装置において、逆浸透膜モジュール３０からの処理水を逆洗浄水及び微細気泡混入洗浄水として再利用し且つろ過膜モジュールからの洗浄排水を微細気泡混入洗浄水として再利用する態様を示す概略説明図である。図１〜３と同様の構成要素には同じ符号を付して説明を割愛する。 FIG. 4 shows a membrane filtration apparatus having a reverse osmosis module 30 in which treated water from the reverse osmosis membrane module 30 is reused as reverse washing water and washing water containing fine bubbles, and washing waste water from the filtration membrane module is fine bubbles. It is a schematic explanatory drawing which shows the aspect recycled as mixing washing water. Components similar to those in FIGS. 1 to 3 are denoted by the same reference numerals and description thereof is omitted.
図４において、微細気泡発生装置１５には、逆浸透膜モジュール３０からの処理水の一部を送液する洗浄水導入管１８ａ及び洗浄排水管１１から洗浄排水の一部を送液する洗浄水導入管１８ｂが接続されている。 In FIG. 4, the fine bubble generator 15 includes a washing water introduction pipe 18 a that sends a part of the treated water from the reverse osmosis membrane module 30 and a washing water that sends a part of the washing waste water from the washing drain pipe 11. An introduction pipe 18b is connected.
図１〜４に示す膜ろ過装置において用いることができるろ過膜１０としては、精密ろ過膜あるいは限外ろ過膜が好適である。ろ過膜１０の膜素材としては、ポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリアクリロニトリル（ＰＡＮ）、ポリエーテルスルホン（ＰＥＳ）、ポリスルホン（ＰＳ）、酢酸セルロース（ＣＡ）などの有機性素材、セラミック、金属などの無機素材を挙げることができる。膜の孔径は、０．００１〜１μｍが好適である。ろ過膜の形態としては、中空糸、チューブラ、平膜などを採用することができるが、本発明では中空糸膜からなる内圧型円筒形モジュール、もしくは加圧型円筒形のモジュールが好適である。 As the filtration membrane 10 that can be used in the membrane filtration apparatus shown in FIGS. 1 to 4, a microfiltration membrane or an ultrafiltration membrane is suitable. The membrane material of the filtration membrane 10 includes polyethylene (PE), polypropylene (PP), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyethersulfone (PES), polysulfone (PS), cellulose acetate (CA), etc. Inorganic materials such as organic materials, ceramics and metals. The pore diameter of the membrane is preferably 0.001 to 1 μm. As the form of the filtration membrane, a hollow fiber, a tubular membrane, a flat membrane, or the like can be adopted. In the present invention, an internal pressure type cylindrical module or a pressure type cylindrical module made of a hollow fiber membrane is suitable.
微細気泡発生装置１５は、原水或いは膜ろ過装置の透過水、ならびにエアを導入して、２相旋回流を発生させて微細気泡を発生させる、いわゆるマイクロバブル発生器を示す。本発明において、微細気泡とは典型的には１〜５０μｍの直径をもつ気泡であるが、必ずしも全ての気泡がこの範囲に収まるものでなくてもよく、一部がこの範囲に含まれていればよい。また、マイクロバブルよりも気泡が小さいナノバブルを発生させることができる発生器を用いても良い。マイクロバブル発生器は種々のものが提案されており、例えば、旋回液流式、スタティックミキサー式、エゼクター式、ベンチュリ式、加圧溶解式、極微細孔式、超音波付加中空針状ノズル、蒸気凝縮式などが挙げられる。例えば、エゼクター式では、気液混合ノズル内で、狭い通路を高速で通過する液流によって生じる負圧を利用してガスを吸引し、下流における管路の拡大により生じたキャビテーションによって吸引ガスが微細に粉砕される。加圧溶解式は、ガスと液との混相をポンプで昇圧（０．５〜１ＭＰａ程度）し、ガス成分を液中に過飽和まで溶解させる。加圧タンク内で未溶解気泡を浮上分離させパージする。過飽和液のみを減圧弁を経て常圧液中にフラッシュさせると、過飽和ガス成分が水中からマイクロバブルになって析出する（化学工学ｖｏｌ．７１、Ｎｏ．３（２００７））。このとき、気液の混合ノズルを通すとより微細な気泡を発生させることができる。気液の混合ノズルは、種々のものが提案されており、ノズル内で、段階的に管路を変化させたもの、管路に球状の障害物を設置したもの、スリットを用いるもの、遠心力によって発生した気体柱を突起物によって破砕するものなど、を採用することができる。 The microbubble generator 15 is a so-called microbubble generator that introduces raw water or permeated water of a membrane filtration device and air to generate a two-phase swirling flow to generate microbubbles. In the present invention, the fine bubbles are typically bubbles having a diameter of 1 to 50 μm, but not all of the bubbles may fall within this range, and some of them are included in this range. That's fine. Moreover, you may use the generator which can generate | occur | produce the nano bubble whose bubble is smaller than a micro bubble. Various types of microbubble generators have been proposed. For example, swirling liquid flow type, static mixer type, ejector type, venturi type, pressure dissolution type, ultra fine hole type, ultrasonically added hollow needle nozzle, steam Condensation type is mentioned. For example, in the ejector type, the gas is sucked using the negative pressure generated by the liquid flow passing through the narrow passage at high speed in the gas-liquid mixing nozzle, and the suction gas is fine due to the cavitation caused by the expansion of the downstream pipe. To be crushed. In the pressure dissolution type, the mixed phase of gas and liquid is increased in pressure (about 0.5 to 1 MPa) with a pump, and the gas component is dissolved in the liquid until supersaturated. Undissolved bubbles are floated and separated in a pressurized tank and purged. When only the supersaturated liquid is flushed into the normal pressure liquid through the pressure reducing valve, the supersaturated gas component is deposited as microbubbles from the water (Chemical Engineering vol. 71, No. 3 (2007)). At this time, if the gas-liquid mixing nozzle is passed, finer bubbles can be generated. A variety of gas-liquid mixing nozzles have been proposed. Inside the nozzle, the pipeline is changed in stages, spherical obstacles are installed in the pipeline, slits are used, centrifugal force What crushes the gas column generated by the above by the projections can be employed.
さらに、本発明の膜ろ過装置は、ろ過膜モジュールのろ過膜の以下の２つの洗浄工程：
（１）当該ろ過膜の透過水側から原水側へ、当該ろ過膜透過水を逆洗浄水として通水する逆洗浄工程；及び
（２）当該洗浄水導入口より当該ろ過膜の原水側に微細気泡混入洗浄水を当該ろ過膜に沿って流し、当該洗浄排水出口から排出する微細気泡洗浄工程
を同時に行う制御部５０を具備する。制御部５０は、ろ過膜モジュールへの微細気泡混入洗浄水の供給と逆洗浄水の供給とを同時に行うため、透過水配管１７と逆洗浄水ライン２２の弁Ｖ１の切り替えと、微細気泡発生装置１５からの微細気泡混入洗浄水の供給と、を制御する。微細気泡混入洗浄水として、逆浸透膜モジュール３０からの透過水及び／又はろ過膜モジュールからの洗浄排水を再利用する態様においては、それぞれの返送管に設けられている弁（例えばＶ１、Ｖ２）の開閉を制御しても良い。
Furthermore, the membrane filtration device of the present invention includes the following two washing steps of the filtration membrane of the filtration membrane module:
(1) a reverse washing step of passing the filtered membrane permeate as backwash water from the permeate side of the filter membrane to the raw water side; and (2) fine from the wash water inlet to the raw water side of the filter membrane. A control unit 50 is provided which simultaneously performs a fine bubble cleaning process in which bubble-containing cleaning water flows along the filtration membrane and is discharged from the cleaning drain outlet. Since the controller 50 simultaneously supplies fine bubble-mixed cleaning water and reverse cleaning water to the membrane filter module, the control unit 50 switches the permeate water pipe 17 and the valve V1 of the reverse cleaning water line 22, and generates a fine bubble generator. 15 and the supply of cleaning water containing fine bubbles. In the aspect in which the permeated water from the reverse osmosis membrane module 30 and / or the washing waste water from the filtration membrane module are reused as washing water containing fine bubbles, valves (for example, V1 and V2) provided in the respective return pipes You may control opening and closing of.
ここで、ろ過膜モジュールへの微細気泡混入洗浄水の供給と、逆洗浄水の供給とが同時とは、微細気泡混入洗浄水と逆洗浄水とが共に合流して膜表面に移動し、これにより、両洗浄水が同時に膜洗浄する時間があるという意味である。 Here, the simultaneous supply of fine bubble-mixed cleaning water and reverse cleaning water to the filtration membrane module means that the fine bubble-mixed cleaning water and the reverse cleaning water merge together and move to the membrane surface. This means that there is time for both washing waters to wash the membrane at the same time.
前記制御部５０は、微細気泡混入洗浄水と逆洗浄水とがろ過膜の膜面で合流するように、同時にろ過膜モジュールに供給し、共通する膜洗浄時間となる様に制御すればよい。これによって、膜面での剥離と押圧との相乗的相互作用によって膜面の汚染物除去が効率的に行える。 The controller 50 may supply the filtration membrane module at the same time so that the fine bubble-mixed washing water and the backwash water merge at the membrane surface of the filtration membrane, and control the common membrane washing time. Accordingly, contaminant removal on the film surface can be efficiently performed by a synergistic interaction between peeling and pressing on the film surface.
具体的な制御部５０の動作は、図１Ａに示す様に、例えば制御部５０には、弁Ｖ１と、微細気泡発生装置１５とが電気的に接続され、該制御部５０が該弁Ｖ１の動作状態を監視し、その動作に合わせて、微細気泡発生装置１５の動作を制御して、逆洗浄水の供給と同時に微細気泡洗浄水を膜面に供給する様にしても良い。または、微細気泡洗浄水を供給する供給管１６に弁Ｖ２を設けて、前記制御部５０が、予め定められた時間（タイミング）で、弁Ｖ１、弁Ｖ２（微細気泡発生装置１５を含めて制御しても良い）を夫々、開閉制御する様にしても良い。なお、前記制御部５０は図１Ａに適用した場合だけでなく、図２〜図４のいずれかにも同様にして適用することが可能である。また、手動操作により弁の開閉を行う場合は、前記制御部５０を省略しても良い。 As shown in FIG. 1A, the specific operation of the control unit 50 is, for example, electrically connected to the control unit 50 with the valve V1 and the fine bubble generating device 15, and the control unit 50 is connected to the valve V1. The operation state may be monitored, and the operation of the fine bubble generating device 15 may be controlled in accordance with the operation so that the fine bubble cleaning water is supplied to the membrane surface simultaneously with the supply of the reverse cleaning water. Alternatively, the valve V2 is provided in the supply pipe 16 for supplying the fine bubble cleaning water, and the control unit 50 controls the valve V1 and the valve V2 (including the fine bubble generator 15) at a predetermined time (timing). May be controlled to open and close. The controller 50 can be applied not only to the case of FIG. 1A but also to any of FIGS. When the valve is opened and closed by manual operation, the control unit 50 may be omitted.
本発明の洗浄方法は、少なくとも溶解性有機物や濁質などの汚染物を含む下水の二次処理水や各種製造排水の排水処理、地下水や用水の浄化処理、海水や汽水などの淡水化処理など、原水を膜ろ過処理するろ過膜に適用することができる。 The cleaning method of the present invention includes at least secondary treatment water of sewage containing various contaminants such as soluble organic matter and turbidity, wastewater treatment of various manufacturing wastewater, purification treatment of groundwater and irrigation water, desalination treatment of seawater, brackish water, etc. It can be applied to a filtration membrane for membrane filtration treatment of raw water.
逆洗浄水としては、膜ろ過後の透過水及び当該透過水をさらに逆浸透膜処理した透過水を用いることが好ましく、微細気泡混入洗浄水としては、原水、洗浄排水、逆浸透膜処理後の透過水を用いることが好ましい。 As the reverse washing water, it is preferable to use the permeated water after membrane filtration and the permeated water obtained by further subjecting the permeated water to a reverse osmosis membrane treatment. It is preferable to use permeated water.
逆洗浄水に添加する薬剤としては、通常、ろ過膜の逆洗浄に用いられている薬剤を制限なく用いることができる。例えば、塩酸、硫酸、硝酸、シュウ酸、クエン酸、アスコルビン酸、過酸化水素、水酸化ナトリウム、次亜塩素酸ナトリウム、キレート剤、界面活性剤および酵素などを好適に用いることができる。 As a chemical | medical agent added to backwashing water, the chemical | medical agent normally used for the backwashing of a filtration membrane can be used without a restriction | limiting. For example, hydrochloric acid, sulfuric acid, nitric acid, oxalic acid, citric acid, ascorbic acid, hydrogen peroxide, sodium hydroxide, sodium hypochlorite, chelating agents, surfactants and enzymes can be preferably used.
キレート剤としては、シュウ酸、クエン酸、酒石酸、グルコン酸などの有機カルボン酸系キレート剤、ＤＥＧ（ジヒドロキシエチルグリシン）、ＴＥＡ（トリエタノールアミン）、ＥＤＴＡ（エチレンジアミン四酢酸）、ＮＴＡ（ニトリロ三酢酸）、ＨＥＤＴＡ（ヒドロキシエチルエチレンジアミン三酢酸）、ＥＤＤＳ（エチレンジアミンコハク酸）などのアミノカルボン酸系キレート剤などが挙げられる。 Chelating agents include organic carboxylic acid chelating agents such as oxalic acid, citric acid, tartaric acid, gluconic acid, DEG (dihydroxyethylglycine), TEA (triethanolamine), EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid) ), Aminocarboxylic acid-based chelating agents such as HEDTA (hydroxyethylethylenediaminetriacetic acid) and EDDS (ethylenediaminesuccinic acid).
界面活性剤としては、硫酸アルキルナトリウム、アルキルベンゼンスルホン酸ナトリウム、α−オレフィンスルホン酸ナトリウム、Ｎ−アシルアミノ酸ナトリウム、Ｎ−（２−スルホ）エチル−Ｎ−メチルアルカンアミドナトリウム、２−スルホコハク酸ジアルキルアミド、アルキルナフタレンスルホン酸ナトリウム、カルボン酸系ポリマーなどのアニオン性界面活性剤、アルキルポリオキシエチレンエーテル、ｐ−アルキルフェニルポリオキシエチレンエーテル、脂肪酸多価アルコールエステル、脂肪酸多価アルコールポリオキシエチレン、脂肪酸ポリオキシエチレンエステル、脂肪酸ショ糖エステルなどのノニオン性界面活性剤などが挙げられる。 Surfactants include alkyl sodium sulfate, sodium alkylbenzene sulfonate, sodium α-olefin sulfonate, sodium N-acylamino acid, sodium N- (2-sulfo) ethyl-N-methylalkanamide, 2-sulfosuccinic acid dialkylamide. , Anionic surfactants such as sodium alkylnaphthalene sulfonate, carboxylic acid polymer, alkyl polyoxyethylene ether, p-alkylphenyl polyoxyethylene ether, fatty acid polyhydric alcohol ester, fatty acid polyhydric alcohol polyoxyethylene, fatty acid poly Nonionic surfactants such as oxyethylene ester and fatty acid sucrose ester are listed.
酵素としては、プロテアーゼ、ペプチダーゼ、リゾチーム、アミラーゼ、リパーゼ、ヘミセルラーゼ、キシラナーゼ、ペクチナーゼ、マンナナーゼ、ラクターゼ、キチナーゼなどが挙げられる。 Examples of the enzyme include protease, peptidase, lysozyme, amylase, lipase, hemicellulase, xylanase, pectinase, mannanase, lactase, chitinase and the like.
また、薬剤の添加量は、原水や汚染物の種類及びろ過膜の汚染程度、並びに逆洗浄水の水質によっても異なるが、たとえば次亜塩素酸ナトリウムの場合には１ｍｇ／Ｌ〜１００ｍｇ／Ｌの範囲が好ましい。逆洗浄水として、ろ過膜透過水や原水を使用するよりも、後述する逆浸透膜モジュールの処理水を利用することにより、同程度の添加量で次亜塩素酸ナトリウムを添加した場合の次亜塩素酸イオンの含有比率が高くなるので、洗浄効果も向上する。 In addition, the amount of the chemical added varies depending on the type of raw water and contaminants, the degree of contamination of the filtration membrane, and the quality of the backwash water. For example, in the case of sodium hypochlorite, 1 mg / L to 100 mg / L A range is preferred. Rather than using filtered membrane permeated water or raw water as reverse wash water, by using the treated water of the reverse osmosis membrane module described later, hypochlorite when sodium hypochlorite is added in the same amount added. Since the content ratio of chlorate ions is increased, the cleaning effect is also improved.
以下、実施例により本発明を具体的に説明する。 Hereinafter, the present invention will be described specifically by way of examples.
［実施例１］
海水の淡水化処理設備におけるろ過膜モジュールの洗浄を実施した。淡水化処理設備の基本構成は図１に示す通りであるが、原水はろ過膜モジュールに導入される前に砂ろ過装置によって大径の夾雑物を除去し、ろ過膜モジュールからの透過水は逆浸透膜モジュール（ポリアミド製膜）に導入して塩類を除去して淡水化処理した。膜ろ過には、孔径０．０１μｍのＰＶＤＦ製限外ろ過膜（東レ ＨＦＵ２００８）を中空糸製の加圧型円筒形モジュールに充填した中空糸型ろ過膜モジュールを用いた。気泡発生装置としては、空気せん断型ポンプ及び加圧溶解タンクを備える株式会社ニクニのマイクロバブルジェネレーター（MBG20ND07ZE-1BG003）を用いた。
[Example 1]
The filtration membrane module was washed in the seawater desalination facility. The basic structure of the desalination treatment facility is as shown in FIG. 1, but the raw water removes large-diameter contaminants by a sand filtration device before being introduced into the filtration membrane module, and the permeated water from the filtration membrane module is reversed. It was introduced into an osmotic membrane module (polyamide membrane) to remove salts and desalinate. For membrane filtration, a hollow fiber type filtration membrane module in which a pressure type cylindrical module made of PVDF with a pore size of 0.01 μm and made of PVDF ultrafiltration membrane (Toray HFU2008) was used. As the bubble generation device, a Nikkuni Micro Bubble Generator (MBG20ND07ZE-1BG003) equipped with an air shearing type pump and a pressurized dissolution tank was used.
原水の処理水量は１０ｍ３／ｄ、砂ろ過は１回／１日〜２日の割合で逆洗浄を行った。 The amount of treated water of the raw water was 10 m 3 / d, and the sand filtration was back-washed at a rate of once / one day to two days.
限外ろ過膜の洗浄は３０分に１回の割合で実施した。逆洗浄水としては、限外ろ過膜透過水を用いて、次亜塩素酸ナトリウムを１０ｍｇ／Ｌとなるように添加した。 The ultrafiltration membrane was washed once every 30 minutes. As the backwash water, ultrafiltration membrane permeate was used, and sodium hypochlorite was added to 10 mg / L.
洗浄方法は、（１）ろ過膜モジュールから原水を抜き出すドレン工程、（２）逆洗浄工程及び微細気泡洗浄工程、（３）ろ過膜モジュールから逆洗浄水及び微細気泡混入洗浄水を抜き出すドレン工程、（４）ろ過膜モジュールに原水を導入する水張り工程、を１セットとした。（２）逆洗浄工程及び微細気泡洗浄工程は同時に行った。 The cleaning method includes (1) a drain process for extracting raw water from the filtration membrane module, (2) a reverse cleaning process and a fine bubble cleaning process, and (3) a drain process for extracting the reverse cleaning water and the cleaning water containing fine bubbles from the filtration membrane module, (4) One set of water filling process for introducing raw water into the filtration membrane module. (2) The reverse cleaning step and the fine bubble cleaning step were performed simultaneously.
約３ヶ月間、上記洗浄方法を実施しながら淡水化処理設備を稼働させた。約３ヶ月後の限外ろ過膜の洗浄後の入口圧を測定したところ、概ね３０ｋＰａであり、運転開始時の２５ｋＰａと比較すると、良好に洗浄されていることが確認できた。 For about 3 months, the desalination treatment facility was operated while carrying out the above washing method. When the inlet pressure after washing the ultrafiltration membrane after about 3 months was measured, it was about 30 kPa, and it was confirmed that it was washed well compared to 25 kPa at the start of operation.
［実施例２］
上記（２）逆洗浄工程及び微細気泡洗浄工程において、ろ過膜モジュールの原水側にコンプレッサを用いて粗大気泡を追加導入した点を除いて、実施例１と同様に洗浄しながら淡水化処理設備を稼働させた。
[Example 2]
In the above-described (2) backwashing step and fine bubble washing step, the desalination treatment facility is installed while washing in the same manner as in Example 1 except that coarse bubbles are additionally introduced into the raw water side of the filtration membrane module using a compressor. It was put into operation.
約３ヶ月後の限外ろ過膜の洗浄後の入口圧を測定したところ、概ね２８ｋＰａであり、運転開始時の２５ｋＰａと比較すると、良好に洗浄されていることが確認できた。 When the inlet pressure after washing the ultrafiltration membrane after about 3 months was measured, it was about 28 kPa, and it was confirmed that it was well washed compared to 25 kPa at the start of operation.
［実施例３］
海水の淡水化処理設備におけるろ過膜モジュールの洗浄を実施した。淡水化処理設備の基本構成は図２に示す通りであるが、原水はろ過膜モジュールに導入される前に砂ろ過装置によって大径の夾雑物を除去し、ろ過膜モジュールからの透過水は逆浸透膜モジュール（ポリアミド製膜）に導入して塩類を除去して淡水化処理した。膜ろ過には、孔径０．０３μｍのＰＥＳ製限外ろ過膜（Pentair製）を充填した内圧型円筒形モジュールをろ過膜モジュールとして用いた。気泡発生装置としては、空気せん断型ポンプ及び加圧溶解タンクを備える株式会社ニクニのマイクロバブルジェネレーター（MBG20ND07ZE-1BG003）を用いた。
[Example 3]
The filtration membrane module was washed in the seawater desalination facility. The basic structure of the desalination treatment facility is as shown in FIG. 2, but the raw water is removed from the large-diameter contaminants by the sand filtration device before being introduced into the filtration membrane module, and the permeated water from the filtration membrane module is reversed. It was introduced into an osmotic membrane module (polyamide membrane) to remove salts and desalinate. For membrane filtration, an internal pressure type cylindrical module filled with a PES ultrafiltration membrane (manufactured by Pentair) having a pore size of 0.03 μm was used as the filtration membrane module. As the bubble generation device, a Nikkuni Micro Bubble Generator (MBG20ND07ZE-1BG003) equipped with an air shearing type pump and a pressurized dissolution tank was used.
原水の処理水量は１０ｍ３／ｄ、砂ろ過は１回／１日〜２日の割合で逆洗浄を行った。 The amount of treated water of the raw water was 10 m 3 / d, and the sand filtration was back-washed at a rate of once / one day to two days.
限外ろ過膜の洗浄を２０分に１回の割合で実施した。逆洗浄水として、逆浸透膜モジュールからのＲＯ透過水を用い、次亜塩素酸ナトリウムを添加しなかった。微細気泡混入洗浄水として、気泡発生装置に導入して微細気泡を混入させた逆浸透膜モジュールからのＲＯ透過水を用いた。 The ultrafiltration membrane was washed once every 20 minutes. As reverse washing water, RO permeated water from the reverse osmosis membrane module was used, and sodium hypochlorite was not added. RO permeated water from a reverse osmosis membrane module introduced into a bubble generator and mixed with fine bubbles was used as washing water containing fine bubbles.
洗浄方法は、（１）ろ過膜モジュールから原水を抜き出すドレン工程、（２）逆洗浄工程及び微細気泡洗浄工程、（３）ろ過膜モジュールから逆洗浄水及び微細気泡混入洗浄水を抜き出すドレン工程、（４）ろ過膜モジュールに原水を導入する水張り工程、を１セットとした。（２）逆洗浄工程及び微細気泡洗浄工程は同時に行った。 The cleaning method includes (1) a drain process for extracting raw water from the filtration membrane module, (2) a reverse cleaning process and a fine bubble cleaning process, and (3) a drain process for extracting the reverse cleaning water and the cleaning water containing fine bubbles from the filtration membrane module, (4) One set of water filling process for introducing raw water into the filtration membrane module. (2) The reverse cleaning step and the fine bubble cleaning step were performed simultaneously.
約３ヶ月間、上記洗浄方法を実施しながら淡水化処理設備を稼働させた。約３ヶ月後の限外ろ過膜の洗浄後の入口圧を測定したところ、概ね２８ｋＰａであり、運転開始時の２５ｋＰａと比較すると、良好に洗浄されていることが確認できた。 For about 3 months, the desalination treatment facility was operated while carrying out the above washing method. When the inlet pressure after washing the ultrafiltration membrane after about 3 months was measured, it was about 28 kPa, and it was confirmed that it was well washed compared to 25 kPa at the start of operation.
［比較例１］
上記（２）逆洗浄工程及び微細気泡洗浄工程を同時に行わず、まず、限外ろ過膜の透過水側に逆洗浄水を導入して逆洗浄した後、逆洗浄水の導入を止めて、次いで、限外ろ過膜の原水側に微細気泡発生装置から微細気泡混入洗浄水を導入して微細気泡洗浄工程を実施した以外は、実施例１と同様に、洗浄しながら淡水化処理設備を稼働させた。
[Comparative Example 1]
(2) The reverse washing step and the fine bubble washing step are not performed at the same time. First, the reverse washing water is introduced into the permeate side of the ultrafiltration membrane to perform the reverse washing, and then the introduction of the reverse washing water is stopped, The desalination treatment facility was operated while cleaning, as in Example 1, except that the microbubble mixed cleaning water was introduced from the microbubble generator to the raw water side of the ultrafiltration membrane and the microbubble cleaning process was performed. It was.
約２ヶ月後の限外ろ過膜の洗浄後の入口圧を測定したところ、概ね４０ｋＰａとなり、運転開始時の２５ｋＰａと比較すると上昇しており、膜表面に汚染物が蓄積していることを確認した。 When the inlet pressure after washing the ultrafiltration membrane after about 2 months was measured, it was about 40 kPa, which was higher than the 25 kPa at the start of operation, confirming that contaminants accumulated on the membrane surface. did.
実施例１〜３及び比較例１の結果を表１及び図５にまとめて示す。図５から、従来の洗浄方法（比較例１）では膜入口圧が約３０ｋＰａに到達するまでに約４週間であったが、本発明の方法（実施例１〜３）によれば約１２週間でも約３０ｋＰａ以下と、洗浄効果が高く、長期的に安定したろ過膜の稼働が可能であることがわかる。 The results of Examples 1 to 3 and Comparative Example 1 are collectively shown in Table 1 and FIG. From FIG. 5, it was about 4 weeks for the conventional cleaning method (Comparative Example 1) to reach the membrane inlet pressure of about 30 kPa, but according to the method of the present invention (Examples 1 to 3), about 12 weeks. However, it can be seen that the cleaning effect is high at about 30 kPa or less, and the filtration membrane can be operated stably over the long term.
Claims (11)
以下の２工程：
（１）当該ろ過膜の透過水側から原水側へ、当該ろ過膜透過水を逆洗浄水として通水する逆洗浄工程；及び
（２）当該洗浄水導入口より当該ろ過膜の原水側に微細気泡混入洗浄水を当該ろ過膜に沿って流し、当該洗浄排水出口から排出する微細気泡洗浄工程
を同時に行うことを特徴とする洗浄方法。 A filtration membrane that obtains membrane filtration permeate by removing contaminants including at least soluble organic matter or turbidity in the raw water, a raw water inlet positioned on the raw water side of the filtration membrane, and a permeate side of the filtration membrane Washing of a filtration membrane module comprising a membrane filtration permeate outlet positioned, a washing water inlet provided at the bottom of the filtration membrane module, and a washing drain outlet provided at the top of the filtration membrane module A method,
The following two steps:
(1) a reverse washing step of passing the filtered membrane permeate as backwash water from the permeate side of the filter membrane to the raw water side; and (2) fine from the wash water inlet to the raw water side of the filter membrane. A cleaning method characterized by simultaneously performing a fine bubble cleaning step of flowing bubble-containing cleaning water along the filtration membrane and discharging the cleaning water from the cleaning drain outlet.
前記（１）逆洗浄工程に用いる逆洗浄水として、前記ろ過膜透過水をさらに逆浸透膜モジュールに通水して塩類を除去した後の逆浸透膜透過水を用いることを特徴とする、請求項１又は２に記載の洗浄方法。 Further comprising a reverse osmosis membrane module downstream of the filtration membrane module;
The reverse osmosis membrane permeated water after passing the filtration membrane permeated water through a reverse osmosis membrane module to remove salts is used as the backwash water used in the (1) reverse washing step. Item 3. The cleaning method according to Item 1 or 2.
前記（２）微細気泡洗浄工程に用いる微細気泡混入洗浄水として、前記ろ過膜透過水をさらに逆浸透膜モジュールに通水して塩類を除去した後の逆浸透膜透過水を再利用し、微細気泡を混入させてなる微細気泡混入逆浸透膜透過水を用いることを特徴とする、請求項１〜３のいずれかに記載の洗浄方法。 Further comprising a reverse osmosis membrane module downstream of the filtration membrane module;
(2) As the fine bubble mixed washing water used in the fine bubble washing step, the filtration membrane permeated water is further passed through a reverse osmosis membrane module to remove salts, and the reverse osmosis membrane permeated water is reused. The cleaning method according to any one of claims 1 to 3, wherein fine bubble-mixed reverse osmosis membrane permeated water in which bubbles are mixed is used.
膜ろ過後の透過水を逆洗浄水として当該ろ過膜モジュールのろ過膜の透過水側に返送する逆洗浄水ラインと、
微細気泡混入洗浄水を当該ろ過膜モジュールの洗浄水導入口に送液する微細気泡混入洗浄水導入管と、
当該微細気泡混入洗浄水を生成する微細気泡発生装置と、
当該ろ過膜モジュールのろ過膜の以下の２つの洗浄工程：
（１）当該ろ過膜の透過水側から原水側へ、当該ろ過膜透過水を逆洗浄水として通水する逆洗浄工程；及び
（２）当該洗浄水導入口より当該ろ過膜の原水側に微細気泡混入洗浄水を当該ろ過膜に沿って流し、当該洗浄排水出口から排出する微細気泡洗浄工程
を同時に行う制御部と、を具備することを特徴とする膜ろ過装置。 A filtration membrane that obtains membrane filtration permeate by removing contaminants including at least soluble organic matter or turbidity in the raw water, a raw water inlet positioned on the raw water side of the filtration membrane, and a permeate side of the filtration membrane A filtration membrane module comprising: a membrane filtration permeate outlet positioned; a washing water inlet provided at the bottom of the filtration membrane module; and a washing drain outlet provided at the top of the filtration membrane module;
Backwash water line for returning the permeated water after membrane filtration to the permeated water side of the filtration membrane of the filtration membrane module as backwash water;
A fine bubble-containing cleaning water introduction pipe for sending the fine bubble-containing cleaning water to the cleaning water inlet of the filtration membrane module;
A fine bubble generating device for generating the fine bubble mixed cleaning water;
The following two washing steps for the membrane of the membrane module:
(1) a reverse washing step of passing the filtered membrane permeate as backwash water from the permeate side of the filter membrane to the raw water side; and (2) fine from the wash water inlet to the raw water side of the filter membrane. A membrane filtration apparatus comprising: a control unit that simultaneously performs a fine bubble washing step of causing bubble-containing washing water to flow along the filtration membrane and discharging it from the washing drain outlet.
前記逆洗浄水ラインは、当該逆浸透膜装置からの透過水を当該ろ過膜モジュールの透過水側に返送することを特徴とする請求項６に記載の膜ろ過装置。 Further comprising a reverse osmosis membrane device for removing salts from the membrane permeate from the filtration membrane module;
The membrane filtration device according to claim 6, wherein the reverse washing water line returns the permeated water from the reverse osmosis membrane device to the permeate side of the filtration membrane module.
当該逆浸透膜装置からの透過水の一部を前記微細気泡発生装置に送液する透過水送水管を具備することを特徴とする請求項６又は７に記載の膜ろ過装置。 Further comprising a reverse osmosis membrane device for removing salts from the membrane permeate from the filtration membrane module;
The membrane filtration device according to claim 6 or 7, further comprising a permeate water feeding pipe for feeding a part of permeated water from the reverse osmosis membrane device to the fine bubble generating device.
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