JP2004008851A - Method for preventing adhesion of microorganism-derived contaminant to electrodialysis vessel and electrodialysis apparatus - Google Patents

Method for preventing adhesion of microorganism-derived contaminant to electrodialysis vessel and electrodialysis apparatus Download PDF

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JP2004008851A
JP2004008851A JP2002163051A JP2002163051A JP2004008851A JP 2004008851 A JP2004008851 A JP 2004008851A JP 2002163051 A JP2002163051 A JP 2002163051A JP 2002163051 A JP2002163051 A JP 2002163051A JP 2004008851 A JP2004008851 A JP 2004008851A
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chlorine
electrodialysis
circulating water
oxidizing agent
microorganism
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Masatoshi Ogawa
小川　正俊
Takahiko Saito
斉藤　隆彦
Tomoko Igarashi
五十嵐　とも子
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Suido Kiko Kaisha Ltd
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Suido Kiko Kaisha Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To prevent the adhesion of microorganism-derived contaminants to an electrodialysis vessel and prevent the damage of an ion-exchange membrane. <P>SOLUTION: A water treatment is conducted while a chlorine-based oxidizing agent is injected only into concentrated circulation water circulated and supplied to a concentration chamber 55 of an electrodialysis vessel 5; and the adhesion of the microorganism-derived contaminants to the electrodialysis vessel is prevented by using the chlorine-based oxidizing agent, and the damage of an ion-exchange membrane is prevented by chlorine without using a reducing agent. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、電気透析槽への微生物由来汚染物の付着防止方法および電気透析装置に関し、更に詳しくは、微生物由来汚染物が電気透析槽に付着するのを塩素系酸化剤を用いて防止すると共に還元剤を用いることなくイオン交換膜の損傷を防止できるようにした電気透析槽への微生物由来汚染物の付着防止方法および電気透析装置に関する。
【０００２】
【従来の技術】
「膜処理技術大系　第６章第２節　脱塩用電気透析システム　第８７７頁〜第８８７頁　１９９１年３月１５日　株式会社フジ・テクノシステム発行」には、電気透析槽に微生物由来汚染物が付着するのを防止するために、脱塩循環水に次亜塩素酸ナトリウム添加や塩素吹込みなどの酸化剤注入を行う方法が記載されている。
また、上記文献には、電気透析槽のイオン交換膜が酸化剤によって性能低下を起こすのを防ぐために、酸化剤注入を行った脱塩循環水が電気透析槽に入る前に還元剤を入れて中和しておく必要があると記載されている。
【０００３】
【発明が解決しようとする課題】
しかし、脱塩循環水に還元剤を入れて中和するのは、処理コストがかかる問題点がある。
そこで、本発明の目的は、微生物由来汚染物が電気透析槽に付着するのを塩素系酸化剤を用いて防止すると共に還元剤を用いることなくイオン交換膜の損傷を防止できるようにした電気透析槽への微生物由来汚染物の付着防止方法および電気透析装置を提供することにある。
【０００４】
【課題を解決するための手段】
第１の観点では、本発明は、電気透析槽の濃縮室に循環供給する濃縮循環水に塩素系酸化剤を注入しながら水処理することを特徴とする電気透析槽への微生物由来汚染物の付着防止方法を提供する。
本願発明者らが鋭意研究したところ、微生物由来汚染物の付着する所は、主として濃縮室を形成するガスケットのスペーサや連通孔の表面であることを見出した。
そこで、上記第１の観点による付着防止方法では、濃縮循環水に塩素系酸化剤を注入しながら水処理することとした。これにより、濃縮室での微生物の繁殖が阻止され、濃縮室を形成するガスケットのスペーサや連通孔の表面に微生物由来汚染物が付着することを防止できる。一方、濃縮室側から脱塩室側へは有効塩素が移動せず、つまり、有効塩素がイオン交換膜を通過しないため、イオン交換膜の損傷を生じない。よって、微生物由来汚染物が電気透析槽に付着するのを塩素系酸化剤を用いて防止できると共に、還元剤を用いなくてもイオン交換膜の損傷を防止できる。
【０００５】
第２の観点では、本発明は、上記構成の付着防止方法において、残留塩素濃度が０．１ｍｇ／Ｌ以上、５ｍｇ／Ｌ以下になるように濃縮循環水に塩素系酸化剤を注入することを特徴とする電気透析槽への微生物由来汚染物の付着防止方法を提供する。
本願発明者らが鋭意研究したところ、残留塩素濃度が０．１ｍｇ／Ｌ以上で微生物の繁殖を十分阻止でき、５ｍｇ／Ｌ以下でイオン交換膜の損傷を十分防止できることが判った。
そこで、上記第２の観点による付着防止方法では、残留塩素濃度が０．１ｍｇ／Ｌ以上、５ｍｇ／Ｌ以下になるように濃縮循環水に塩素系酸化剤を注入することとした。
【０００６】
第３の観点では、本発明は、上記構成の付着防止方法において、塩素系酸化剤を間欠的に注入して水処理することを特徴とする電気透析槽への微生物由来汚染物の付着防止方法を提供する。
本願発明者らが鋭意研究したところ、塩素系酸化剤を連続的に注入するのではなく、間欠的に注入しても、微生物の繁殖を十分阻止できると共にイオン交換膜の損傷を十分防止できることが判った。
そこで、上記第３の観点による付着防止方法では、濃縮循環水に間欠的に塩素系酸化剤を注入することとした。
【０００７】
第４の観点では、本発明は、上記構成の付着防止方法において、塩素系酸化剤が次亜塩素酸ナトリウムであることを特徴とする電気透析槽への微生物由来汚染物の付着防止方法を提供する。
上記第４の観点による付着防止方法では、次亜塩素酸ナトリウムを用いるが、これは浄水処理で広く用いられており、入手しやすく、安全性も高く、取り扱いが容易となる。
【０００８】
第５の観点では、本発明は、電気透析槽と、該電気透析槽の脱塩室に脱塩循環水を循環供給する脱塩循環水循環供給手段と、前記電気透析槽の濃縮室に濃縮循環水を循環供給する濃縮循環水循環供給手段と、前記濃縮循環水に塩素系酸化剤を注入する塩素系酸化剤注入手段とを具備したことを特徴とする電気透析装置を提供する。
上記第５の観点による電気透析装置では、上記第１〜第４の観点による付着防止方法を好適に実施できる。
【０００９】
【発明の実施の形態】
以下、図を参照して本発明の実施の形態を説明する。なお、これにより本発明が限定されるものではない。
【００１０】
図１は、本発明の一実施形態にかかる電気透析装置の構成図である。
この電気透析装置１００において、海水やかん水のような原水は、原水槽１に貯留され、原水槽１から原水ポンプＰ１により、砂ろ過あるいは繊維ろ材を用いた前処理用ろ過器２に送られる。前処理用ろ過器では、原水を除濁処理し、濁度０．１度程度にする。そして、除濁された原水は、脱塩循環水槽３と濃縮循環水槽６とに送られる。濃縮循環水槽６にも送るのは、濃縮循環水の濃度が高くなり過ぎないようにするためである。
【００１１】
脱塩循環水循環ポンプＰ３は、脱塩循環水槽３から脱塩循環水を電気透析槽５の脱塩室５５へ送る。脱塩室５５を通過した脱塩循環水は、脱塩循環水槽３に戻る。また、脱塩循環水の一部が原水循環槽３から処理水として配水池２０に貯留される。
【００１２】
濃縮循環水循環ポンプＰ６は、濃縮循環水槽６から濃縮循環水を電気透析槽５の濃縮室５６へ送る。濃縮室５６を通過した濃縮循環水は、濃縮循環水槽６に戻る。
【００１３】
電気透析槽５は、−濃縮室５６−陰イオン交換膜Ａ−脱塩室５５−陽イオン交換膜Ｋ−という積層単位を多数積層した構造であり、両端に陽極室５３と陰極室５４とが設けてある。そして、陽極室５３と陰極室５４とには、電解液ポンプＰ８により電解液槽８から電解液が循環供給される。
【００１４】
ｐＨ調整液供給ポンプＰ１０は、ｐＨ調整液槽１０からｐＨ調整液を濃縮循環水槽６および電解液槽８へ送る。電解槽８へ送るのは、ｐＨ値を一定に保って、電極への生成物の付着を防止するためである。
【００１５】
塩素系酸化剤液供給ポンプＰ１２は、塩素系酸化剤液槽１２から塩素系酸化剤液を濃縮循環水槽６へ送る。また、必要に応じて、前処理用ろ過器２にも塩素系酸化剤液を送る。例えば、前処理用ろ過器２の逆流洗浄時毎に次亜塩素酸ナトリウムを塩素注入率１０ｍｇ／Ｌ程度で注入し消毒処理すれば、電気透析槽５に供給される原水の微生物低減に効果的である。
【００１６】
図２は、電気透析槽５の脱塩室５５と濃縮室５６の構造を示す斜視図である。
脱塩室５５は、ガスケット５５ｇのスペーサ５５ｂにより形成され、陰極側の陽イオン交換膜Ｋと陽極側の陰イオン交換膜Ａとに挟まれており、連通孔５５ａで脱塩循環水の流路と連通している。
濃縮室５６は、ガスケット５６ｇのスペーサ５６ｂにより形成され、陰極側の陰イオン交換膜Ａと陽極側の陽イオン交換膜Ｋとに挟まれており、連通孔５６ａで濃縮循環水の流路と連通している。
【００１７】
［実施例１］
スチレン−ジビニルベンゼン共重合樹脂製の陽イオン交換膜Ｋおよび陰イオン交換膜Ａを４０対積層した電気透析槽５を用いた。有効膜面積は０．４８５ｍ２／対である。
図３に示す原水を用い、残留塩素濃度１０ｍｇ／Ｌ，５ｍｇ／Ｌ，０．１ｍｇ／Ｌ，０．０５ｍｇ／Ｌとなるように濃縮循環水槽６のみへ次亜塩素酸ナトリウムを注入しつつ２ヶ月間連続運転したところ、図４に示す結果を得た。
この結果から、濃縮循環水に残留塩素濃度５ｍｇ／Ｌ〜０．１ｍｇ／Ｌの塩素系酸化剤を注入しながら水処理することで、微生物由来汚染物の付着を防止できると共に、還元剤を用いなくても、イオン交換膜Ｋ，Ａが損傷を受けないことが判った。
【００１８】
［比較例１］
スチレン−ジビニルベンゼン共重合樹脂製の陽イオン交換膜Ｋおよび陰イオン交換膜Ａを４０対積層した電気透析槽５を用いた。有効膜面積は０．４８５ｍ２／対である。
原水として地下水（ｐＨ：７．１、ＮＯ３−Ｎ：１３．８ｍｇ／Ｌ、電気伝導度：３２２μＳ／ｃｍ、濁度：０度、色度：０．４度、鉄：０．０２ｍｇ／Ｌ、マンガン：＜０．０１ｍｇ／Ｌ、ＫＭｎＯ４消費量：１．１ｍｇ／Ｌ）を用い、残留塩素濃度０．２〜０．３ｍｇ／Ｌとなるように脱塩循環水槽３および濃縮循環水槽６へ次亜塩素酸ナトリウムを注入しつつ２ヶ月間連続運転したところ、脱塩室５５および濃縮室５６の両方に微生物由来汚染物の付着は認められなかった。また、陽イオン交換膜Ｋの膜抵抗値には、変化が認められなかった。しかしながら、陰イオン交換膜Ａの膜抵抗値は、２０％増加した。これは、陰イオン交換膜Ａが残留塩素により損傷を受けたことを現している。
【００１９】
［実施例２］
スチレン−ジビニルベンゼン共重合樹脂製の陽イオン交換膜Ｋおよび陰イオン交換膜Ａを１９０対積層したものを１スタックとし、これを４スタック重ね締め付けした構造の電気透析槽５を用いた。有効膜面積は０．４８５ｍ２／対である。
図３に示す原水を用い、濃縮排水量２．５ｍ３／ｈに対して塩素注入率２ｍｇ／Ｌで濃縮循環水槽６のみへ次亜塩素酸ナトリウムを１日１回、２時間添加しつつ連続運転したところ、図５に示す結果を得た。
この結果から、濃縮循環水に塩素注入率２ｍｇ／Ｌで塩素系酸化剤を間欠的に注入しながら水処理することで、濃縮循環水中の従属性栄養細菌を０〜３００個／ｍＬの間に留めることができることが判った。
【００２０】
また、同じ条件で１年間連続運転したところ、図６に示す結果を得た。
この結果から、濃縮循環水ライン圧力（濃縮循環水ポンプ圧力）は、当初約０．０４ＭＰａであり、１年間連続運転しても約０．０５ＭＰａであり、濃縮循環水ライン圧力の上昇は殆ど認められなかった。つまり、微生物由来汚染物の付着を防止できた。
【００２１】
なお、原水中にマンガンイオンが含まれている場合、塩素系酸化剤（次亜塩素酸ナトリウム）を連続的に注入すると、マンガンイオンが酸化析出してイオン交換膜Ｋ，Ａに付着し、透析機能を損なうことがあるが、短時間の間欠注入であれば、マンガンイオンが酸化析出しない。従って、マンガンイオンを含有する原水に対しては、塩素系酸化剤（次亜塩素酸ナトリウム）を間欠注入するのが好ましい。
【００２２】
塩素系酸化剤として、次亜塩素酸ナトリウムの代わりに、クロラミンを添加しても、同様な効果が得られる。ただし、クロラミンは、次亜塩素酸ナトリウムに比べて殺菌力が弱いため、次亜塩素酸ナトリウムの４倍以上の注入率が必要となる。
【００２３】
［比較例２］
スチレン−ジビニルベンゼン共重合樹脂製の陽イオン交換膜Ｋおよび陰イオン交換膜Ａを１９０対積層したものを１スタックとし、これを４スタック重ね締め付けした構造の電気透析槽５を用いた。有効膜面積は０．４８５ｍ２／対である。
図３に示す原水を用い、濃縮排水量２．５ｍ３／ｈに対して次亜塩素酸ナトリウムを添加しないで連続運転したところ、図７に示す結果を得た。
この結果から、濃縮循環水ラインの圧力は１ヶ月〜２ヶ月で約２倍程度まで上昇することが判る。さらに、濃縮室５６内の流速分布が不均一となるためにスケールが形成されて電気抵抗が増大し、電気透析槽５の機能を損なうため、解体洗浄を余儀なくされた。
【００２４】
【発明の効果】
本発明の電気透析槽への微生物由来汚染物の付着防止方法および電気透析装置によれば、微生物由来汚染物が電気透析槽に付着するのを塩素系酸化剤を用いて防止することが出来ると共に、還元剤を用いることなく、塩素でイオン交換膜が損傷するのを防止できるようになる。
【図面の簡単な説明】
【図１】本発明の一実施形態にかかる電気透析装置を示す構成図である。
【図２】電気透析増の構造を示す斜視図である。
【図３】原水の水質を示す図表である。
【図４】本発明の実施例１の結果を示す図表である。
【図５】本発明の実施例２の結果を示す図表である。
【図６】本発明の実施例２の結果を示す図表である。
【図７】比較例２の結果を示す図表である。
【符号の説明】
５　　　　電気透析槽
６　　　　濃縮循環水槽
１２　　　塩素系酸化剤液槽
５５　　　脱塩室
５６　　　濃縮室
Ａ　　　　陰イオン交換膜
Ｋ　　　　陽イオン交換膜[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for preventing adhesion of microorganism-derived contaminants to an electrodialysis tank and an electrodialysis device, and more particularly, to preventing a microorganism-derived contaminant from adhering to an electrodialysis tank using a chlorine-based oxidizing agent. The present invention relates to a method for preventing microbial contaminants from adhering to an electrodialysis tank and an electrodialysis apparatus capable of preventing damage to an ion exchange membrane without using a reducing agent.
[0002]
[Prior art]
"Membrane Treatment Technology, Chapter 6, Section 2, Electrodialysis System for Desalination, pp. 877 to 887, published by Fuji Techno System Co., Ltd., March 15, 1991," contains microbial contaminants in electrodialysis tanks. A method of injecting an oxidizing agent such as addition of sodium hypochlorite or blowing of chlorine into desalinated circulating water in order to prevent the deposition of water is described.
Also, in the above document, in order to prevent the performance of the ion exchange membrane of the electrodialysis tank from being degraded by the oxidizing agent, a reducing agent is added before the desalted circulating water injected with the oxidizing agent enters the electrodialysis tank. It is stated that it must be neutralized.
[0003]
[Problems to be solved by the invention]
However, the neutralization of the desalting circulating water by adding a reducing agent has a problem that the treatment cost is high.
Accordingly, an object of the present invention is to provide an electrodialysis apparatus which prevents contamination of microorganism-derived contaminants from adhering to an electrodialysis tank using a chlorine-based oxidizing agent and prevents damage to an ion exchange membrane without using a reducing agent. An object of the present invention is to provide a method for preventing adhesion of microorganism-derived contaminants to a tank and an electrodialysis apparatus.
[0004]
[Means for Solving the Problems]
In a first aspect, the present invention provides a method for treating microbial-derived contaminants in an electrodialysis tank, wherein water is treated while a chlorine-based oxidizing agent is injected into concentrated circulating water supplied to the concentrating chamber of the electrodialysis tank. A method for preventing adhesion is provided.
The inventors of the present application have conducted extensive studies and found that the places where microorganism-derived contaminants adhere are mainly on the surfaces of the spacers and communication holes of the gasket forming the concentration chamber.
Therefore, in the adhesion preventing method according to the first aspect, water treatment is performed while pouring a chlorine-based oxidizing agent into the concentrated circulating water. This prevents the growth of microorganisms in the concentration chamber, and prevents the contamination of microorganism-derived contaminants from adhering to the surfaces of the spacers and communication holes of the gasket forming the concentration chamber. On the other hand, the available chlorine does not move from the concentration chamber side to the desalting chamber side, that is, the available chlorine does not pass through the ion exchange membrane, so that the ion exchange membrane is not damaged. Therefore, it is possible to prevent the microorganism-derived contaminants from adhering to the electrodialysis tank using the chlorine-based oxidizing agent, and to prevent the ion exchange membrane from being damaged without using the reducing agent.
[0005]
In a second aspect, the present invention provides the method for preventing adhesion according to the above configuration, wherein a chlorine-based oxidizing agent is injected into the concentrated circulating water such that the residual chlorine concentration becomes 0.1 mg / L or more and 5 mg / L or less. Disclosed is a method for preventing microbial contaminants from adhering to an electrodialysis tank.
The present inventors have conducted intensive studies and found that the residual chlorine concentration of 0.1 mg / L or more can sufficiently prevent the growth of microorganisms and the residual chlorine concentration of 5 mg / L or less can sufficiently prevent damage to the ion exchange membrane.
Therefore, in the adhesion preventing method according to the second aspect, the chlorine-based oxidizing agent is injected into the concentrated circulating water so that the residual chlorine concentration becomes 0.1 mg / L or more and 5 mg / L or less.
[0006]
In a third aspect, the present invention provides the method for preventing adhesion of microorganism-derived contaminants to an electrodialysis tank, wherein the method comprises the steps of intermittently injecting a chlorine-based oxidizing agent and treating the water with water. I will provide a.
The inventors of the present application have conducted intensive research and have found that even if the chlorine-based oxidizing agent is not injected continuously but intermittently, the propagation of microorganisms can be sufficiently prevented and the ion exchange membrane can be sufficiently prevented from being damaged. understood.
Therefore, in the adhesion preventing method according to the third aspect, the chlorine-based oxidizing agent is intermittently injected into the concentrated circulating water.
[0007]
In a fourth aspect, the present invention provides the method for preventing adhesion of microorganism-derived contaminants to an electrodialysis tank, wherein the chlorine-based oxidizing agent is sodium hypochlorite in the method for preventing adhesion of the above structure. I do.
In the adhesion preventing method according to the fourth aspect, sodium hypochlorite is used, which is widely used in water purification treatment, is easily available, has high safety, and is easy to handle.
[0008]
In a fifth aspect, the present invention provides an electrodialysis tank, a desalting circulating water circulating supply means for circulating desalinating circulating water to a desalting chamber of the electrodialysis tank, and a condensing circuit for concentrating and circulating water in a concentrating chamber of the electrodialysis tank. An electrodialysis apparatus comprising: a concentrated circulating water circulating / supplying means for circulating and supplying water; and a chlorine-based oxidizing agent injecting means for injecting a chlorine-based oxidizing agent into the concentrated circulating water.
In the electrodialysis apparatus according to the fifth aspect, the adhesion preventing methods according to the first to fourth aspects can be suitably performed.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to this.
[0010]
FIG. 1 is a configuration diagram of an electrodialysis apparatus according to one embodiment of the present invention.
In the electrodialysis apparatus 100, raw water such as seawater or brackish water is stored in a raw water tank 1 and sent from the raw water tank 1 to a pretreatment filter 2 using sand filtration or a fiber filter medium by a raw water pump P1. In the pretreatment filter, the raw water is subjected to a turbidity treatment to make the turbidity about 0.1 degree. The clarified raw water is sent to the desalination circulating water tank 3 and the concentrated circulating water tank 6. The reason why the concentrated circulating water is also sent to the concentrated circulating water tank 6 is to prevent the concentration of the concentrated circulating water from becoming too high.
[0011]
The desalting circulating water circulation pump P3 sends the desalting circulating water from the desalting circulating water tank 3 to the desalting chamber 55 of the electrodialysis tank 5. The desalted circulating water that has passed through the desalting chamber 55 returns to the desalting circulating water tank 3. In addition, part of the desalinated circulating water is stored in the distribution reservoir 20 as treated water from the raw water circulation tank 3.
[0012]
The concentrated circulating water circulation pump P6 sends the concentrated circulating water from the concentrated circulating water tank 6 to the concentration chamber 56 of the electrodialysis tank 5. The concentrated circulating water that has passed through the concentration chamber 56 returns to the concentrated circulating water tank 6.
[0013]
The electrodialysis tank 5 has a structure in which a large number of laminated units of-a concentration chamber 56-an anion exchange membrane A-a desalination chamber 55-a cation exchange membrane K-are laminated, and an anode chamber 53 and a cathode chamber 54 are provided at both ends. It is provided. The electrolyte is circulated and supplied from the electrolyte tank 8 to the anode chamber 53 and the cathode chamber 54 by the electrolyte pump P8.
[0014]
The pH adjusting liquid supply pump P10 sends the pH adjusting liquid from the pH adjusting liquid tank 10 to the concentrated circulating water tank 6 and the electrolytic solution tank 8. The reason why the solution is sent to the electrolytic cell 8 is to keep the pH value constant and prevent the product from adhering to the electrode.
[0015]
The chlorine-based oxidant liquid supply pump P12 sends the chlorine-based oxidant liquid from the chlorine-based oxidant liquid tank 12 to the concentrated circulating water tank 6. In addition, if necessary, the chlorine-based oxidant solution is also sent to the pretreatment filter 2. For example, if sodium hypochlorite is injected at a chlorine injection rate of about 10 mg / L and disinfected each time the pretreatment filter 2 is backwashed, it is effective in reducing microorganisms in the raw water supplied to the electrodialysis tank 5. It is.
[0016]
FIG. 2 is a perspective view showing the structure of the desalting chamber 55 and the concentration chamber 56 of the electrodialysis tank 5.
The desalting chamber 55 is formed by the spacer 55b of the gasket 55g, and is sandwiched between the cation exchange membrane K on the cathode side and the anion exchange membrane A on the anode side. Is in communication with
The concentration chamber 56 is formed by a spacer 56b of a gasket 56g, and is sandwiched between the anion exchange membrane A on the cathode side and the cation exchange membrane K on the anode side, and communicates with the flow path of the concentrated circulating water through the communication hole 56a. are doing.
[0017]
[Example 1]
An electrodialysis tank 5 in which 40 pairs of a cation exchange membrane K and an anion exchange membrane A made of a styrene-divinylbenzene copolymer resin were used was used. The effective membrane area is 0.485 m 2 / pair.
Using the raw water shown in FIG. 3, sodium hypochlorite was injected only into the concentrated circulating water tank 6 so that the residual chlorine concentration became 10 mg / L, 5 mg / L, 0.1 mg / L, and 0.05 mg / L. After continuous operation for months, the results shown in FIG. 4 were obtained.
From these results, it is possible to prevent the attachment of microorganism-derived contaminants by performing water treatment while injecting a chlorine-based oxidant having a residual chlorine concentration of 5 mg / L to 0.1 mg / L into the concentrated circulating water, and using a reducing agent. It was found that the ion exchange membranes K and A were not damaged even if they were not.
[0018]
[Comparative Example 1]
An electrodialysis tank 5 in which 40 pairs of a cation exchange membrane K and an anion exchange membrane A made of a styrene-divinylbenzene copolymer resin were used was used. The effective membrane area is 0.485 m 2 / pair.
Groundwater as raw water (pH: 7.1, NO 3 -N: 13.8 mg / L, electric conductivity: 322 μS / cm, turbidity: 0 °, chromaticity: 0.4 °, iron: 0.02 mg / L) , Manganese: <0.01 mg / L, KMnO 4 consumption: 1.1 mg / L) and the desalting circulating water tank 3 and the condensing circulating water tank 6 so that the residual chlorine concentration becomes 0.2 to 0.3 mg / L. As a result of continuous operation for two months while injecting sodium hypochlorite, adhesion of microbial contaminants to both the desalting chamber 55 and the concentrating chamber 56 was not observed. No change was observed in the membrane resistance value of the cation exchange membrane K. However, the membrane resistance of the anion exchange membrane A increased by 20%. This indicates that the anion exchange membrane A was damaged by the residual chlorine.
[0019]
[Example 2]
An electrodialysis tank 5 having a structure in which a 190-layer stack of a cation exchange membrane K and an anion exchange membrane A made of a styrene-divinylbenzene copolymer resin was used as one stack and four stacks were tightened was used. The effective membrane area is 0.485 m 2 / pair.
Using the raw water shown in FIG. 3, continuous operation while adding sodium hypochlorite once a day for 2 hours only to the concentrated circulating water tank 6 at a chlorine injection rate of 2 mg / L with respect to the concentrated wastewater amount of 2.5 m 3 / h Then, the result shown in FIG. 5 was obtained.
From this result, by performing water treatment while intermittently injecting a chlorine-based oxidizing agent into the concentrated circulating water at a chlorine injection rate of 2 mg / L, the heterotrophic bacteria in the concentrated circulating water can be reduced to 0 to 300 bacteria / mL. It turned out that it could be stopped.
[0020]
Moreover, when the continuous operation was performed under the same conditions for one year, the result shown in FIG. 6 was obtained.
From these results, the concentrated circulating water line pressure (concentrated circulating water pump pressure) was initially about 0.04 MPa, and even after one year of continuous operation, was about 0.05 MPa. I couldn't. That is, adhesion of microbial contaminants could be prevented.
[0021]
In the case where manganese ions are contained in the raw water, when a chlorine-based oxidizing agent (sodium hypochlorite) is continuously injected, the manganese ions are oxidized and deposited, adhere to the ion exchange membranes K and A, and are dialyzed. Although the function may be impaired, manganese ions are not oxidized and precipitated when intermittently implanted for a short time. Therefore, it is preferable to intermittently inject a chlorine-based oxidizing agent (sodium hypochlorite) into raw water containing manganese ions.
[0022]
A similar effect can be obtained by adding chloramine instead of sodium hypochlorite as the chlorine-based oxidizing agent. However, chloramine has a weaker bactericidal activity than sodium hypochlorite, and therefore requires an injection rate four times or more that of sodium hypochlorite.
[0023]
[Comparative Example 2]
An electrodialysis tank 5 having a structure in which a 190-layer stack of a cation exchange membrane K and an anion exchange membrane A made of a styrene-divinylbenzene copolymer resin was used as one stack and four stacks were tightened was used. The effective membrane area is 0.485 m 2 / pair.
Using the raw water shown in FIG. 3 and continuously operating without adding sodium hypochlorite to the concentrated wastewater amount of 2.5 m 3 / h, the results shown in FIG. 7 were obtained.
From this result, it is understood that the pressure of the concentrated circulating water line increases to about twice in one to two months. Further, since the flow rate distribution in the concentration chamber 56 becomes non-uniform, a scale is formed and the electric resistance is increased, and the function of the electrodialysis tank 5 is impaired.
[0024]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the method for preventing adhesion of microorganism-derived contaminants to an electrodialysis tank and the electrodialysis apparatus of the present invention, it is possible to prevent the microorganism-derived contaminants from adhering to the electrodialysis tank using a chlorine-based oxidizing agent. In addition, it is possible to prevent chlorine from damaging the ion exchange membrane without using a reducing agent.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an electrodialysis apparatus according to one embodiment of the present invention.
FIG. 2 is a perspective view showing the structure of an electrodialysis booster.
FIG. 3 is a table showing the quality of raw water.
FIG. 4 is a table showing the results of Example 1 of the present invention.
FIG. 5 is a table showing the results of Example 2 of the present invention.
FIG. 6 is a chart showing the results of Example 2 of the present invention.
FIG. 7 is a table showing the results of Comparative Example 2.
[Explanation of symbols]
5 Electrodialysis tank 6 Concentrating circulating water tank 12 Chlorine oxidizing agent liquid tank 55 Desalination room 56 Concentration room A Anion exchange membrane K Cation exchange membrane

Claims (5)

電気透析槽の濃縮室に循環供給する濃縮循環水に塩素系酸化剤を注入しながら水処理することを特徴とする電気透析槽への微生物由来汚染物の付着防止方法。A method for preventing microbial contaminants from adhering to an electrodialysis tank, wherein water is treated while a chlorine-based oxidizing agent is injected into concentrated circulating water supplied to a concentrating chamber of the electrodialysis tank. 請求項１に記載の付着防止方法において、残留塩素濃度が０．１ｍｇ／Ｌ以上、５ｍｇ／Ｌ以下になるように濃縮循環水に塩素系酸化剤を注入することを特徴とする電気透析槽への微生物由来汚染物の付着防止方法。The method for preventing adhesion according to claim 1, wherein a chlorine-based oxidizing agent is injected into the concentrated circulating water so that the residual chlorine concentration is 0.1 mg / L or more and 5 mg / L or less. A method for preventing adhesion of microorganism-derived contaminants. 請求項１または請求項２に記載の付着防止方法において、塩素系酸化剤を間欠的に注入して水処理することを特徴とする電気透析槽への微生物由来汚染物の付着防止方法。The method for preventing adhesion of microorganism-derived contaminants to an electrodialysis tank according to claim 1 or 2, wherein a chlorine-based oxidizing agent is intermittently injected to perform water treatment. 請求項１から請求項３のいずれかに記載の付着防止方法において、塩素系酸化剤が次亜塩素酸ナトリウムであることを特徴とする電気透析槽への微生物由来汚染物の付着防止方法。The method for preventing adhesion of microorganism-derived contaminants to an electrodialysis tank according to any one of claims 1 to 3, wherein the chlorine-based oxidizing agent is sodium hypochlorite. 電気透析槽と、該電気透析槽の脱塩室に脱塩循環水を循環供給する脱塩循環水循環供給手段と、前記電気透析槽の濃縮室に濃縮循環水を循環供給する濃縮循環水循環供給手段と、前記濃縮循環水に塩素系酸化剤を注入する塩素系酸化剤注入手段とを具備したことを特徴とする電気透析装置。An electrodialysis tank, a desalting circulating water circulating supply means for circulating desalinating circulating water to the desalting chamber of the electrodialysis tank, and a condensing circulating water circulating supplying means for circulating the condensing circulating water to the concentrating chamber of the electrodialysis tank An electrodialysis apparatus comprising: a chlorine-based oxidizing agent injecting a chlorine-based oxidizing agent into the concentrated circulating water.
JP2002163051A 2002-06-04 2002-06-04 Method for preventing adhesion of microorganism-derived contaminant to electrodialysis vessel and electrodialysis apparatus Pending JP2004008851A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018051453A (en) * 2016-09-27 2018-04-05 オルガノ株式会社 Electric type deionized water production device and method for driving the same
CN109475674A (en) * 2016-07-27 2019-03-15 日本多宁股份有限公司 The cleaning method of dialyzate manufacturing device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109475674A (en) * 2016-07-27 2019-03-15 日本多宁股份有限公司 The cleaning method of dialyzate manufacturing device
JP2018051453A (en) * 2016-09-27 2018-04-05 オルガノ株式会社 Electric type deionized water production device and method for driving the same

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