JP4599803B2

JP4599803B2 - Demineralized water production equipment

Info

Publication number: JP4599803B2
Application number: JP2003080543A
Authority: JP
Inventors: 聡山田; 求小泉; 望育野
Original assignee: Kurita Water Industries Ltd
Current assignee: Kurita Water Industries Ltd
Priority date: 2002-04-05
Filing date: 2003-03-24
Publication date: 2010-12-15
Anticipated expiration: 2023-03-24
Also published as: JP2004000919A

Description

【０００１】
【発明の属する技術分野】
本発明は脱塩水製造装置に係り、特に、ホウ素及びＴＯＣが著しく低減された高水質の脱塩水を、高い水回収率で製造することができる脱塩水製造装置に関する。
【０００２】
【従来の技術】
従来、市水、地下水、工水等の原水から超純水を製造する超純水製造装置は、基本的に、前処理装置、一次純水製造装置及び二次純水製造装置から構成される。このうち、前処理装置は、凝集、浮上、濾過、除濁膜装置等で構成される。一次純水製造装置は、活性炭吸着塔、紫外線（ＵＶ）酸化装置、化学的酸化装置、脱気装置等のうちの１種又は２種以上の装置と、脱塩装置とで構成され、このうち脱塩装置は、逆浸透（ＲＯ）膜分離装置、電気再生式脱塩装置、イオン交換装置（混床式イオン交換装置ないしはイオン交換純水装置）の１種或いは２種以上の組み合わせにより構成される。また、二次純水製造装置は、一次純水製造装置と同様な装置単位を適宜組み合わせたものであり、一般的には、低圧ＵＶ酸化装置、混床式イオン交換装置及び限外濾過（ＵＦ）膜分離装置で構成される。
【０００３】
これらの各装置単位において、原水の脱塩は、ＲＯ膜分離装置、電気再生式脱塩装置及び混床式イオン交換装置で行われる。また、原水中の微粒子の除去は、ＲＯ膜分離装置及びＵＦ膜分離装置で行われ、ＴＯＣ成分の除去は、ＲＯ膜分離装置、イオン交換純水装置、低圧ＵＶ酸化装置で行われる。
【０００４】
このような超純水製造装置により工水、その他の水を原水として超純水を製造する場合、得られる超純水の純度が悪く、管理値を満足し得ない場合がある。例えば、抵抗率１８．２４ＭΩ・ｃｍの超純水を製造する超純水製造装置において、得られる超純水の抵抗率が１８．０ＭΩ・ｃｍあるいはそれ以下にまで低下する場合がある。このような純度低下は、特に、装置の運転時間が長くなった場合に著しい。
【０００５】
しかして、この純度低下の原因は、原水中のホウ素にあることが知られている。
【０００６】
従来、ホウ素の除去手段としては、強塩基性アニオン交換樹脂、ホウ素選択性キレート樹脂、或いはｐＨ９以上のアルカリ性条件でのＲＯ膜分離処理が知られており、本出願人は、先に脱塩装置の後段にホウ素選択性キレート樹脂を充填したホウ素吸着樹脂塔を設けてホウ素を除去するようにした超純水製造装置を提案した（特開平８−８９９５６号公報）。
【０００７】
しかし、強塩基性アニオン交換樹脂は、単位樹脂量当たりのホウ素の吸着量が少なく、ホウ素の除去効率が悪い。また、ＲＯ膜分離処理では、ｐＨ９以上のアルカリ性であればホウ素を除去し得るが、超純水の製造プロセスのように、ｐＨ中性の系内では、ホウ素は解離せずにホウ酸として存在するため、除去し得ず、濃縮水中に濃縮される。
【０００８】
ホウ素選択性キレート樹脂は、一般の強塩基性アニオン交換樹脂よりも単位樹脂量当たりのホウ素の吸着量は多いが、被処理水中のホウ素濃度が低いと単位樹脂量当たりのホウ素吸着量は小さいものとなる。このため、脱塩装置の後段にホウ素吸着樹脂塔を設けた特開平８−８９９５６号公報の装置では、ホウ素濃度の低い脱塩水がホウ素吸着樹脂塔に導入されるため、単位樹脂量当たりのホウ素吸着量が少なく、ホウ素吸着樹脂塔への通水可能な時間が短く、ホウ素吸着樹脂塔を頻繁に再生する必要があるという欠点がある。即ち、原水である市水、工水等のホウ素濃度は、通常２０μｇ／Ｌ程度である。従って、このような低ホウ素濃度の原水を脱塩処理して得られる処理水のホウ素濃度は更に低く、このため、ホウ素選択性キレート樹脂の吸着能を有効利用することができない。
【０００９】
また、ホウ素選択性キレート樹脂は、有機物（ＴＯＣ）の溶出の問題があり、ホウ素吸着樹脂塔の後段にＲＯ膜分離装置やＵＶ酸化装置等を設けてＴＯＣの除去を行わないと、得られる超純水のＴＯＣが安定しないという問題もある。そして、ホウ素吸着樹脂塔の後段にＲＯ膜分離装置やＵＶ酸化装置を設けた場合には、これらの装置の負荷が大きいという問題もある。
【００１０】
ところで、脱塩装置としてのＲＯ膜分離装置や電気再生式脱塩装置にあっては、水回収率を高めるために、濃縮水を循環処理することが行われている。この場合、例えば、脱塩装置として、ＲＯ膜分離装置を２段に直列に配置した場合、或いは、ＲＯ膜分離装置とその後段の電気再生式脱塩装置を設けた場合に、比較的純度の高い、後段のＲＯ膜分離装置又は電気再生式脱塩装置の濃縮水を前段のＲＯ膜分離装置の導入側に戻すことが考えられる。しかしながら、このように濃縮水を回収して循環処理を行う場合、前述の如く、ｐＨ中性におけるＲＯ膜分離処理ではホウ素の除去率は低く、５０〜６０％程度であるため、ＲＯ膜分離装置で除去し得なかったホウ素が系内で濃縮され、経時により処理水水質の悪化を招くという問題がある。
【００１１】
【特許文献１】
特開平８−８９９５６号公報
【００１２】
【発明が解決しようとする課題】
本発明は上記従来の問題点を解決し、ホウ素及びＴＯＣ濃度が著しく低い高水質の脱塩水を、高い水回収率で安定に製造することができる脱塩水製造装置を提供することを目的とする。
【００１３】
【課題を解決するための手段】
本発明（請求項１）の脱塩水製造装置は、ホウ素含有水が供給され、該ホウ素含有水を脱塩水と濃縮水とに分離する脱塩装置と、該脱塩装置から排出される濃縮水を、該脱塩装置の上流側に戻す返送路と、該返送路の途中に設けられ、該濃縮水中のホウ素を除去するホウ素除去装置とを有する脱塩水製造装置であって、前記ホウ素除去装置は、ホウ素選択性吸着体を充填したホウ素吸着塔であり、該脱塩装置は、逆浸透膜分離装置及び／又は電気再生式脱塩装置により構成され、該脱塩装置とホウ素除去装置との間の返送路に濃縮水処理用の逆浸透膜分離装置が設けられており、前記脱塩装置の濃縮水を該濃縮水処理用の逆浸透膜分離装置で処理して得られた透過水が前記返送路を通して前記ホウ素除去装置に導入されることを特徴とする。
本発明（請求項２）の脱塩水製造装置は、ホウ素含有水が供給され、該ホウ素含有水を脱塩水と濃縮水とに分離する脱塩装置と、該脱塩装置から排出される濃縮水を、該脱塩装置の上流側に戻す返送路と、該返送路の途中に設けられ、該濃縮水中のホウ素を除去するホウ素除去装置とを有する脱塩水製造装置であって、前記ホウ素除去装置は、ホウ素選択性吸着体を充填したホウ素吸着塔であり、該脱塩装置は、逆浸透膜分離装置と、該逆浸透膜分離装置の透過水が導入される電気再生式脱塩装置とを備え、該電気再生式脱塩装置から排出される濃縮水が、前記返送路を経て前記ホウ素除去装置に導入されることを特徴とする。
本発明（請求項３）の脱塩水製造装置は、ホウ素含有水が供給され、該ホウ素含有水を脱塩水と濃縮水とに分離する脱塩装置と、該脱塩装置から排出される濃縮水を、該脱塩装置の上流側に戻す返送路と、該返送路の途中に設けられ、該濃縮水中のホウ素を除去するホウ素除去装置とを有する脱塩水製造装置であって、前記ホウ素除去装置は、ホウ素選択性吸着体を充填したホウ素吸着塔であり、前記脱塩装置が前段の逆浸透膜分離装置と、該前段の逆浸透膜分離装置の透過水が導入される後段の逆浸透膜分離装置とを備え、該後段の逆浸透膜分離装置の濃縮水が前記返送路を経て前記ホウ素除去装置に導入されることを特徴とする。
【００１４】
本発明の脱塩水製造装置では、脱塩装置から排出される濃縮水を循環処理することにより水回収率を高めることができる。このように、脱塩装置の濃縮水を循環処理した場合、前述の如く、系内でのホウ素の濃縮の問題があるが、本発明では、この循環濃縮水をホウ素除去装置で処理してホウ素を除去した後脱塩装置の上流側に戻すため、濃縮水を循環処理することによるホウ素の濃縮の問題は解消される。しかも、本発明では、比較的ホウ素濃度の高い脱塩装置の濃縮水をホウ素除去装置で処理するため、例えば、ホウ素選択性キレート樹脂等のホウ素選択性吸着体による処理において、単位吸着体当たりのホウ素吸着量が多くなり、従って、処理水量を大きく（通水時間を長く）することができ、吸着体の再生頻度を低減することができる。
【００１５】
また、ホウ素選択性キレート樹脂等のホウ素選択性吸着体から溶出するＴＯＣは、脱塩装置で除去することができるため、このホウ素選択性吸着体から溶出するＴＯＣの除去のための装置を設ける必要もなく、脱塩水のＴＯＣの増加も防止することができる。
【００１６】
ところで、特開平８−８９９５６号公報に記載される装置のように、脱塩装置の後段にホウ素吸着樹脂塔を設けたものでは、ホウ素選択性キレート樹脂からのＴＯＣの溶出の問題に加えて、次のような不具合もある。即ち、脱塩処理系統にホウ素吸着樹脂塔を設けた場合、樹脂の再生時に通水を中断することは、脱塩水の製造を中止することになる。このため、再生時も連続通水を行うために、ホウ素吸着樹脂塔を２塔設ける必要がある。
【００１７】
これに対して本発明の脱塩水製造装置であれば、ホウ素吸着樹脂塔の再生時又は交換時には、通水を中断して濃縮水を系外に排出すれば良く、再生のためにホウ素吸着塔を２塔設ける必要はない。
【００１８】
なお、このように濃縮水を処理する場合、脱塩処理系統での処理に比べて、ホウ素吸着塔に通水される処理水量が少ないことにより、ホウ素吸着塔の再生頻度を低減することができるという効果を得ることもできる。
【００１９】
また、特開平８−８９９５６号公報に記載される装置のように脱塩装置の後段にホウ素吸着樹脂塔を設けた場合には、脱塩装置の後段にブースターポンプを設け、脱塩装置の処理水を昇圧してホウ素吸着樹脂塔に通水する必要が生じる場合もあるが、本発明のように、濃縮水を通水する場合には、このような問題も解消される。
【００２０】
本発明において、脱塩装置は、ＲＯ膜分離装置及び／又は電気再生式脱塩装置により構成され、例えば、
(1) ＲＯ膜分離装置とこのＲＯ膜分離装置の透過水が導入される電気再生式脱塩装置とで構成される脱塩装置
或いは
(2) 前段のＲＯ膜分離装置と、この前段のＲＯ膜分離装置の透過水が導入される後段のＲＯ膜分離装置とで構成される脱塩装置
等を採用することができる。
【００２１】
なお、電気再生式脱塩装置は、電極（陽極、陰極）の間に複数のアニオン交換膜及びカチオン交換膜を交互に配列して濃縮室と脱塩室とを交互に形成し、脱塩室にイオン交換樹脂、イオン交換繊維もしくはグラフト交換体等からなるアニオン交換体とカチオン交換体とを混合もしくは複層状に充填したものであり、特公平４−７２５６７号公報、特許第２７５１０９０号公報、特許第２６９９２５６号公報等に記載されている。電気再生式脱塩装置は、水解離によってＨ^＋イオンとＯＨ⁻イオンとを生成させ、脱塩室内に充填されているイオン交換体を連続して再生することによって、効率的な脱塩処理が可能であり、従来から脱塩処理に広く用いられてきたイオン交換樹脂装置のような薬品を用いた再生処理を必要とせず、完全な連続採水が可能であるという利点がある。
【００２２】
このような本発明の脱塩水製造装置において、循環処理する濃縮水は、比較的純度の高いＲＯ膜分離装置の後段の電気再生式脱塩装置又は後段のＲＯ膜分離装置の濃縮水であることが好ましい。
【００２３】
脱塩装置の前段のＲＯ膜分離装置の濃縮水を循環処理する場合、或いは、脱塩装置としてＲＯ膜分離装置を１段のみ設け、その濃縮水を循環処理する場合、この濃縮水は塩類濃度が高いため、これを脱塩装置に循環すると脱塩装置の負荷が大きくなり過ぎ、好ましくない。従って、この場合には、濃縮水の返送路にこの濃縮水を脱塩処理するためのＲＯ膜分離装置（以下このＲＯ膜分離装置を「回収ＲＯ膜分離装置」と称す場合がある。）を設け、濃縮水を回収ＲＯ膜分離装置で脱塩処理した後ホウ素除去装置でホウ素の除去を行い、その後脱塩装置に導入することが好ましい。
【００２４】
この回収ＲＯ膜分離装置で濃縮水中の塩類を除去する場合、この濃縮水中にシリカが濃縮されていると、回収ＲＯ膜分離装置においてシリカスケールが生成して脱塩が困難になる恐れがあるため、回収ＲＯ膜分離装置に導入する濃縮水にスケール防止剤を添加するか、酸を添加してスケールの生成し難い条件に調整することが好ましい。
【００２５】
【発明の実施の形態】
以下に図面を参照して本発明の脱塩水製造装置の実施の形態を詳細に説明する。
【００２６】
図１〜６は本発明の脱塩水製造装置の実施の形態を示す系統図である。
【００２７】
図１の脱塩水製造装置は、原水を前処理装置１で処理した後ＲＯ膜分離装置３及び電気再生式脱塩装置４よりなる脱塩装置２で処理して脱塩水を製造するものである。前段のＲＯ膜分離装置３の濃縮水は、系外へ排出し、このＲＯ膜分離装置３の透過水を電気再生式脱塩装置４で処理して脱塩水を得ると共に、濃縮水をホウ素除去装置５に送給してホウ素を除去した後、ホウ素処理水をＲＯ膜分離装置３の入口側に戻して循環処理する。
【００２８】
図２の脱塩水製造装置は、原水を前処理装置１で処理した後、２段に配置したＲＯ膜分離装置３Ａ，３Ｂ及び電気再生式脱塩装置４よりなる脱塩装置２Ａで処理して脱塩水を製造するものである。前段のＲＯ膜分離装置３Ａの濃縮水は系外へ排出し、このＲＯ膜分離装置３Ａの透過水を後段のＲＯ膜分離装置３Ｂで処理し、このＲＯ膜分離装置３Ｂの透過水を電気再生式脱塩装置４で処理して脱塩水を得る。後段のＲＯ膜分離装置３Ｂの濃縮水及び電気再生式脱塩装置４の濃縮水はホウ素除去装置５に送給してホウ素を除去した後、ホウ素処理水をＲＯ膜分離装置３Ａの入口側に戻して循環処理する。
【００２９】
図３の脱塩水製造装置は、原水を前処理装置１で処理した後、ＲＯ膜分離装置３及び混床式イオン交換装置６よりなる脱塩装置２Ｂで処理して脱塩水を製造するものである。前段のＲＯ膜分離装置３の透過水は混床式イオン交換装置６で処理して脱塩水を得る。ＲＯ膜分離装置３の濃縮水は回収ＲＯ膜分離装置３Ｋで処理し、得られた透過水をホウ素除去装置５に送給してホウ素を除去した後、ホウ素処理水をＲＯ膜分離装置３の入口側に戻して循環処理する。回収ＲＯ膜分離装置３Ｋの濃縮水は系外へ排出する。
【００３０】
図４の脱塩水製造装置は、原水を前処理装置１で処理した後、ＲＯ膜分離装置３及び２段に配置した電気再生式脱塩装置４Ａ，４Ｂよりなる脱塩装置２Ｃで処理して脱塩水を製造するものである。ＲＯ膜分離装置３の濃縮水は系外へ排出し、このＲＯ膜分離装置３の透過水を前段の電気再生式脱塩装置４Ａで処理し、この電気再生式脱塩装置４Ａの透過水を後段の電気再生式脱塩装置４Ｂで処理して脱塩水を得る。前段の電気再生式脱塩装置４Ａの濃縮水及び後段の電気再生式脱塩装置４Ｂの濃縮水はホウ素除去装置５に送給してホウ素を除去した後、ホウ素処理水をＲＯ膜分離装置３の入口側に戻して循環処理する。
【００３１】
図５の脱塩水製造装置は、原水を前処理装置１で処理した後、２段に配置したＲＯ膜分離装置３Ａ，３Ｂ及び２段に配置した電気再生式脱塩装置４Ａ，４Ｂよりなる脱塩装置２Ｄで処理して脱塩水を製造するものである。前段のＲＯ膜分離装置３Ａの濃縮水は系外へ排出し、このＲＯ膜分離装置３Ａの透過水を後段のＲＯ膜分離装置３Ｂで処理し、このＲＯ膜分離装置３Ｂの透過水を前段電気再生式脱塩装置４Ａで処理し、この電気再生式脱塩装置４Ａの透過水を後段の電気再生式脱塩装置４Ｂで処理して脱塩水を得る。後段のＲＯ膜分離装置３Ｂの濃縮水及び前段の及び後段の電気再生式脱塩装置４Ａ，４Ｂの濃縮水はホウ素除去装置５に送給してホウ素を除去した後、ホウ素処理水をＲＯ膜分離装置３Ａの入口側に戻して循環処理する。
【００３２】
図６の脱塩水製造装置は、原水を前処理装置１で処理した後、２段に配置したＲＯ膜分離装置３Ａ，３Ｂ及び混床式イオン交換装置６よりなる脱塩装置２Ｅで処理して脱塩水を製造するものである。前段のＲＯ膜分離装置３Ａの濃縮水は系外へ排出し、このＲＯ膜分離装置３Ａの透過水を後段のＲＯ膜分離装置３Ｂで処理し、このＲＯ膜分離装置３Ｂの透過水を混床式イオン交換装置６で処理して脱塩水を得る。後段のＲＯ膜分離装置３Ｂの濃縮水はホウ素除去装置５に送給してホウ素を除去した後、ホウ素処理水をＲＯ膜分離装置３Ａの入口側に戻して循環処理する。
【００３３】
本発明において、原水としては、市水、工水、井水、その他のプロセス排水、或いはこれらの混合水を用いることができる。一般に、これらの原水のホウ素濃度は２０〜３０μｇ／Ｌの範囲であるが、本発明はホウ素濃度１〜５００μｇ／Ｌの原水に適用可能である。
【００３４】
前処理装置１としては、特に制限はなく、除濁装置、活性炭吸着塔、脱気装置、脱炭酸装置等が必要に応じて組み合わせて用いられる。
【００３５】
脱塩装置としては、前処理水を脱塩水と濃縮水とに分離する装置を含むものであれば良く、一般的には、ＲＯ膜分離装置及び／又は電気再生式脱塩装置、更に必要に応じてイオン交換装置等が用いられる。本発明の脱塩水製造装置の脱塩装置は、図１に示すＲＯ膜分離装置３と電気再生式脱塩装置４との組み合せ、図２に示す２段ＲＯ膜分離装置３Ａ，３Ｂと電気再生式脱塩装置４との組み合せ、図３に示すＲＯ膜分離装置３と混床式イオン交換装置６との組み合せ、図４に示すＲＯ膜分離装置３と２段電気再生式脱塩装置４Ａ，４Ｂとの組み合せ、図５に示す２段ＲＯ膜分離装置３Ａ，３Ｂと２段電気再生式脱塩装置４Ａ，４Ｂとの組み合せ、図６に示す２段ＲＯ膜分離装置３Ａ，３Ｂと混床式イオン交換装置６との組み合せに何ら限定されず、例えば、
(1) ＲＯ膜分離装置又は電気再生式脱塩装置の１段処理
(2) ＲＯ膜分離装置の２段又は３段以上の多段処理
(3) ＲＯ膜分離装置と電気再生式脱塩装置と混床式イオン交換装置
等を採用することもできる。また、ＲＯ膜分離装置の２段処理において、２段目のＲＯ膜分離装置の入口水に、炭酸成分のイオン化の目的でＮａＯＨ，ＫＯＨ等のアルカリ剤を添加してｐＨ調整を行うなどの処理も任意に採用することができる。また、非再生式イオン交換装置を併用しても良く、例えば、図１において、電気再生式脱塩装置４の後段に更に非再生式イオン交換装置を設けても良い。また、図６の混床式イオン交換装置６の代りに非再生式イオン交換装置を設けても良い。また、これらの脱塩装置を構成する装置単位間に脱気装置等の脱塩装置以外の装置を設けても良い。
通常の場合、このような脱塩装置の被処理水のｐＨは３〜１０の範囲とされる。
【００３６】
本発明の脱塩水製造装置では、水回収率の向上のために、脱塩装置から排出される濃縮水を循環処理するが、この循環処理による系内でのホウ素の濃縮を防止するために、濃縮水をホウ素除去装置５で処理してホウ素を除去する。
【００３７】
本発明において、ホウ素を除去して循環処理する濃縮水は、ＲＯ膜分離装置及び／又は電気再生式脱塩装置を２段以上に設けた脱塩装置の場合には、塩類濃度の高い前段の装置の濃縮水は系外へ排出し、比較的純度の高い後段の電気再生式脱塩装置又はＲＯ膜分離装置の濃縮水であることが好ましい。このため、図１，４の脱塩水製造装置では、ＲＯ膜分離装置３の後段の電気再生式脱塩装置４又は電気再生式脱塩装置４Ａ，４Ｂの濃縮水を循環処理し、図２，５，６の脱塩水製造装置では、ＲＯ膜分離装置３Ａの後段のＲＯ膜分離装置３Ｂの濃縮水と更にその後段の電気再生式脱塩装置４，４Ａ，４Ｂの濃縮水を循環処理し、いずれも前段のＲＯ膜分離装置３，３Ａの濃縮水を系外へ排出している。
【００３８】
ＲＯ膜分離装置又は電気再生式脱塩装置を１段のみ設けた脱塩装置の場合や、１段目のＲＯ膜分離装置又は電気再生式脱塩装置の濃縮水を循環処理する必要がある場合には、図３に示す如く、濃縮水の返送系路にこの濃縮水を処理するための回収ＲＯ膜分離装置３Ｋを設けてＲＯ膜分離処理し、濃縮水を系外へ排出し、得られた透過水を循環処理することが好ましい。
【００３９】
図３に示す如く、回収ＲＯ膜分離装置３Ｋで濃縮水中の塩類を除去する場合、この濃縮水中にシリカが濃縮されていると、回収ＲＯ膜分離装置３Ｋにおいてシリカスケールが生成して脱塩が困難になる恐れがあるため、回収ＲＯ膜分離装置に導入する濃縮水にスケール防止剤を添加するか、酸を添加してｐＨ４程度のスケールの生成し難い条件に調整することが好ましい。
【００４０】
この回収ＲＯ膜分離装置３ＫにおけるＲＯ膜分離処理は、ｐＨ中性又は酸性条件となり、このようなｐＨ条件ではホウ素はイオン化しないため、回収ＲＯ膜分離装置３Ｋでは除去されず、その殆どが透過水中に移行するようになる。通常の場合、回収ＲＯ膜分離装置３Ｋにおけるホウ素除去率は２０〜３０％程度である。このような回収ＲＯ膜分離装置３Ｋを設ける場合、この回収ＲＯ膜分離装置３Ｋの水回収率は５０〜７０％程度とすることが好ましい。
【００４１】
なお、図１，２や図４〜６の脱塩水製造装置にあっても前段のＲＯ膜分離装置３，３Ａの濃縮水を回収ＲＯ膜分離装置で処理した後ホウ素除去装置５に送給して循環処理することも可能であるが、一般的には、前段ＲＯ膜分離装置の濃縮水は系外へ排出することが好ましい。
【００４２】
本発明において、循環濃縮水を処理するホウ素除去装置５としては、ホウ素選択性吸着体を充填したホウ素吸着塔を用いる。
【００４３】
ホウ素選択性吸着体としては、ホウ素選択性キレート樹脂のような粒状物でも良く、また、繊維状物でも良い。これらを吸着塔内に充填し、循環濃縮水を通水することによりホウ素を吸着除去することができる。また、ホウ素選択性吸着体の微粒子を循環濃縮水に添加してホウ素を除去しても良い。しかし、微粒子を使用する場合は後段に微粒子除去工程が必要になり、また、吸着塔の場合は運転操作が容易であり、再生により繰り返し使用できることから、吸着塔方式を採用することが好ましい。吸着塔方式を採用した場合、一塔式でも良く、また、二塔式など複数塔式でも良い。複数塔式では吸着塔を直列に配置して使用しても良く、並列に配置して使用しても良い。また、吸着塔は再生が必要になった時にその場で再生する再生型でも良いし、別途再生済みの吸着塔と交換する非再生型でも良い。
【００４４】
ホウ素選択性吸着体としては、イオン交換作用でホウ素を吸着するものや、キレート作用でホウ素を吸着するものがあるが、本発明においてはいずれをも用いることができる。なお、ホウ素選択性のない通常のイオン交換樹脂では、濃縮水の処理であり、共存塩類によって速やかに樹脂の吸着能が飽和し、再生頻度が高くなるので好ましくない。
【００４５】
本発明において、ホウ素選択性吸着体としては、各種のものを用いることができるが、例えば、市販のホウ素選択性キレート樹脂の「ダイヤイオンＣＲＢ」（三菱化学（株））、ホウ素選択性キレート繊維の「キレストファイバーＧＲＹ」（キレスト（株））等を用いることができる。
【００４６】
例えば、「ダイヤイオンＣＲＢ０２」は、以下に示す如く、スチレン・ジビニルベンゼンの骨格にホウ素選択性の高いキレート形成基としてＮグルカミン基を導入した化学構造を有している。
【００４７】
【化１】

【００４８】
このＮグルカミン基は、弱塩基性アニオン交換樹脂と同様の３級アミン型になっており、次のような反応でホウ酸性ホウ素を吸着する。
【００４９】
【化２】

【００５０】
ホウ素選択性吸着体を充填した吸着塔への濃縮水の通水ＳＶは特に限定されない。ホウ素を吸着して破過したホウ素選択性吸着体は、ＨＣｌ、Ｈ_２ＳＯ_４等の酸、又はＮａＯＨ、ＫＯＨ等のアルカリ剤を用いて任意の方法で再生することができる。
【００５１】
一方、ホウ素と錯体を形成するキレート剤としては、液体キレート剤として知られているタイロン：（ＯＨ）_２Ｃ_６Ｈ_２（ＳＯ_３Ｎａ）_２やクロモトロープ酸ナトリウム：（ＯＨ）_２Ｃ_１０Ｈ_４（ＳＯ_３Ｎａ）_２などが使用でき、また、ソルビット、マンニットなどの多価アルコール類或いはクルクミンなどを用いることができる。濃縮水をｐＨ５以下の酸性としてこれらのキレート剤を添加すると、ホウ素と錯体を形成してホウ素を捕捉する。形成された錯体は脱塩装置で排除される。
【００５２】
本発明においては、ホウ素濃度の高い濃縮水を処理することから、前述の如く、ホウ素選択性キレート樹脂等のホウ素選択性吸着体のホウ素吸着量を高めることができる。即ち、工水等の原水のホウ素濃度は２０〜３０μｇ／Ｌ程度であり、この程度の希薄水では、ホウ素吸着量が低く、ホウ素選択性吸着体の再生頻度が高いものとなるが、例えば、このような原水を１段目のＲＯ膜分離装置で処理して得られる透過水のホウ素濃度は１０〜１５μｇ／Ｌ程度であり、この透過水を電気再生式脱塩装置で４〜５倍程度に濃縮処理して得られる濃縮水のホウ素濃度は８０μｇ／Ｌ程度となる。
【００５３】
また、ｐＨ中性の処理において、１段目ＲＯ膜分離装置の濃縮水のホウ素濃度は５０〜６０μｇ／Ｌ程度であり、これを回収ＲＯ膜分離装置で処理して得られる透過水は、回収ＲＯ膜分離装置のホウ素除去率が２０〜３０％程度と低いため、処理する前のホウ素濃度と大差はなく、５０〜６０μｇ／Ｌ程度である。
【００５４】
このように、濃縮水を処理することで、ホウ素濃度５０〜１００μｇ／Ｌ程度の水がホウ素除去装置５に導入されるようになるため、ホウ素選択性吸着体の単位量当たりのホウ素吸着量を増大させることができる。なお、温泉地区の市水のようにホウ素濃度が１００μｇ／Ｌ程度の原水の場合には、ホウ素除去装置５にはホウ素濃度２００μｇ／Ｌ程度の濃縮水が導入されるようになる。
【００５５】
本発明ではまた、脱塩装置で脱塩水と濃縮水とに分離され、原水に対して水量が低減された濃縮水をホウ素除去装置５で処理することによっても、ホウ素選択性吸着体の再生頻度を低減することができる。
【００５６】
本発明の脱塩水製造装置は、一般的には、前述のような前処理装置、一次純水製造装置及び二次純水製造装置から構成される超純水製造装置に組み込まれて用いられ、従って、図１〜６に示した脱塩装置とホウ素除去装置の他に、任意の処理装置が前段又は後段に設けられていても良い。
【００５７】
【実施例】
以下に実施例及び比較例を挙げて本発明をより具体的に説明する。説明の便宜上、まず、比較例を挙げる。
【００５８】
比較例１
図７に示す脱塩水製造装置により脱塩水の製造を行った。
【００５９】
原水は野木町水（ｐＨ：６．９，導電率：１３．０ｍＳ／ｍ、ホウ素濃度：２１〜２５μｇ／Ｌ）であり、この原水を、前処理装置１としての精密濾過（ＭＦ）膜分離装置（孔径：０．２μｍ）で濾過した後、脱炭酸塔（入口ｐＨ：５〜５．５）にて脱炭酸処理し、前処理水（ｐＨ：５．８〜６．２，導電率：１４．４ｍＳ／ｍ、ホウ素濃度：２１〜２５μｇ／Ｌ）を得た。
【００６０】
この前処理水をＲＯ膜分離装置（日本電工（株）製「ＥＳ２０」４インチ，２本）３に０．８ＭＰａの圧力で通水して下記条件で処理し、濃縮水を系外へ排出した。ＲＯ膜分離装置３の透過水を電気再生式脱塩装置（栗田工業（株）製「Ｍ４０型」１台）４に通水して下記条件で処理して脱塩水を得、濃縮水を系外へ排出した。
［ＲＯ膜分離装置３の処理条件］
水回収率：７５％
給水量：４４４Ｌ／ｈｒ
処理水（透過水）量：３３３Ｌ／ｈｒ
［電気再生式脱塩装置４の処理条件］
水回収率：９０％
処理水（脱塩水）量：３００Ｌ／ｈｒ
濃縮水量：３３Ｌ／ｈｒ
【００６１】
この処理において、ＲＯ膜分離装置３の処理水（透過水：ＲＯ処理水）のホウ素濃度、脱塩水（電気再生式脱塩装置４の処理水）のホウ素濃度及びＴＯＣ濃度、及び系全体の水回収率は表１に示す通りであった。
【００６２】
比較例２
図８に示す脱塩水製造装置により、比較例１において、電気再生式脱塩装置４の濃縮水をそのままＲＯ膜分離装置３の入口側に戻して循環処理したこと以外は同様にして脱塩水の製造を行い、このときのＲＯ処理水のホウ素濃度、脱塩水のホウ素濃度及びＴＯＣ濃度、及び系全体の水回収率を表１に示した。
【００６３】
この比較例２では、電気再生式脱塩装置４の濃縮水を循環処理したため水回収率は比較例１よりも高くなったが、循環処理によるホウ素の濃縮でＲＯ処理水及び脱塩水のホウ素濃度が高くなっている。
【００６４】
実施例１
図１に示す本発明の脱塩水製造装置により、比較例２において、電気再生式脱塩装置４の濃縮水の返送路にホウ素除去装置５を設け、電気再生式脱塩装置４の濃縮水を、ホウ素除去装置５でホウ素の除去処理を行った後ＲＯ膜分離装置３の入口側に戻したこと以外は同様にして脱塩水の製造を行った。
【００６５】
用いたホウ素除去装置５は、三菱化学（株）製ホウ素選択性キレート樹脂「ダイヤイオンＣＲＢ０２」を３．３Ｌ充填したホウ素吸着樹脂塔であり、このホウ素吸着樹脂塔に電気再生式脱塩装置４の濃縮水（給水ホウ素濃度：１３０〜１５０μｇ／Ｌ）をＳＶ：１０ｈｒ^−１で通水して処理した。
【００６６】
このときのＲＯ処理水のホウ素濃度、脱塩水のホウ素濃度及びＴＯＣ濃度、及び系全体の水回収率は表１に示す通りであり、濃縮水の循環処理で水回収率を高めたにもかかわらず、ホウ素及びＴＯＣ濃度の低い高水質の脱塩水を得ることができた。
【００６７】
このホウ素吸着樹脂塔は、通水１０６０ｈｒで破過したため、通水１０６０ｈｒに１回の頻度で再生を行った。
【００６８】
比較例３
図９に示す脱塩水製造装置により、比較例２において、ＲＯ膜分離装置３と電気再生式脱塩装置４との間に実施例１で用いたものと同様のホウ素吸着樹脂塔（ホウ素選択性キレート樹脂量は実施例１と同量の３．３Ｌ，通水ＳＶは１００ｈｒ^−１，給水量は３３３Ｌ／ｈｒ）を設け、ＲＯ膜分離装置３の透過水をホウ素吸着樹脂塔で処理した後電気再生式脱塩装置４に通水して脱塩水を得ると共に、電気再生式脱塩装置４の濃縮水をそのままＲＯ膜分離装置３の入口側に戻して循環処理したこと以外は同様にして脱塩水の製造を行った。
【００６９】
このときのＲＯ処理水のホウ素濃度、脱塩水のホウ素濃度及びＴＯＣ濃度、及び系全体の水回収率は表１に示す通りであり、電気再生式脱塩装置４の濃縮水を循環処理したため水回収率は高く、また、ＲＯ膜分離装置３と電気再生式脱塩装置４との間にホウ素吸着樹脂塔を設けたため脱塩水のホウ素濃度も低いが、ＴＯＣ濃度が高い。このＴＯＣ濃度の増加は、ホウ素選択性キレート樹脂からのＴＯＣの溶出に起因するものと認められる。
【００７０】
また、ホウ素吸着樹脂塔の給水であるＲＯ処理水のホウ素濃度は１５〜１７μｇ／Ｌで、このホウ素吸着樹脂塔は通水６４０ｈｒで破過したため、通水６４０ｈｒに１回の頻度で再生を行う必要があり、再生頻度が高かった。
【００７１】
また、このように、ホウ素吸着樹脂塔を脱塩処理系統に設ける比較例３では、次の点からも工業的に不利である。即ち、実施例１のように濃縮水をホウ素吸着樹脂塔に通水する場合には、ホウ素吸着樹脂塔の再生時には通水を中断して濃縮水を系外へ排出すれば良いが、脱塩処理系統の水の通水を中断することはできないため、ホウ素吸着樹脂塔の再生の際も連続通水するために、ホウ素吸着樹脂塔が２塔必要となる。
【００７２】
比較例４
図１０に示す脱塩水製造装置により、比較例１において、電気再生式脱塩装置４の後段に実施例１で用いたものと同様のホウ素吸着樹脂塔（ホウ素選択性キレート樹脂量は実施例１と同量の３，３Ｌ，通水ＳＶは９１ｈｒ^−１，給水量は３００Ｌ／ｈｒ）を設け、電気再生式脱塩装置４の処理水をホウ素吸着樹脂塔で処理したこと以外は同様にして脱塩水の製造を行った。濃縮水の循環処理は行わなかった。
【００７３】
このときのＲＯ処理水のホウ素濃度、脱塩水のホウ素濃度及びＴＯＣ濃度、及び系全体の水回収率は表１に示す通りであり、濃縮水の循環処理を行わないため水回収率は低い。電気再生式脱塩装置４の処理水を更にホウ素吸着樹脂塔で処理したため、脱塩水のホウ素濃度は低いが、ホウ素選択性キレート樹脂からのＴＯＣの溶出でＴＯＣ濃度が高いため、後段に更にＴＯＣ処理装置が必要となり、このＴＯＣ除去装置の負荷が大きいため、装置が大型化する。
【００７４】
本比較例のホウ素吸着樹脂塔の給水（電気再生式脱塩装置の処理水）のホウ素濃度は４〜６μｇ／Ｌであり、このホウ素吸着樹脂塔は通水１８４７ｈｒで破過したため、通水１８４７ｈｒに１回の頻度で再生を行う必要があった。この再生頻度は、ホウ素吸着樹脂塔を用いた実施例１及び比較例３，４の中で最も低いが、このように脱塩処理系統にホウ素吸着樹脂塔を設けることは、前述の比較例３の場合のように、ホウ素吸着樹脂塔の再生のためにホウ素吸着樹脂塔が２塔必要となるという欠点がある上に、電気再生式脱塩装置４の後段にホウ素吸着樹脂塔を設けることは、ＴＯＣの溶出のみならず、次の点からも好ましくない。
【００７５】
即ち、電気再生式脱塩装置４の後段に背圧０．１ＭＰａ以上の負荷が生じ、給水限界圧力０．４ＭＰａ程度となる場合が多いため、送水距離によっては、ホウ素吸着樹脂塔に供給する水の昇圧のために電気再生式脱塩装置４の後段にブースターポンプが必要になる場合がある。
【００７６】
【表１】

【００７７】
【発明の効果】
以上詳述した通り、本発明の脱塩水製造装置によれば、ホウ素及びＴＯＣ濃度が著しく低い高水質の脱塩水を、高い水回収率で安定に製造することができる。しかも、本発明によれば、ホウ素除去に用いるホウ素選択性吸着体の単位量当たりのホウ素吸着量を増加させることができ、ホウ素選択性吸着体を有効利用して再生頻度を低減することができる。
【図面の簡単な説明】
【図１】本発明の脱塩水製造装置の実施の形態を示す系統図である。
【図２】本発明の脱塩水製造装置の他の実施の形態を示す系統図である。
【図３】本発明の脱塩水製造装置の別の実施の形態を示す系統図である。
【図４】本発明の脱塩水製造装置の別の実施の形態を示す系統図である。
【図５】本発明の脱塩水製造装置の別の実施の形態を示す系統図である。
【図６】本発明の脱塩水製造装置の別の実施の形態を示す系統図である。
【図７】比較例１で用いた脱塩水製造装置を示す系統図である。
【図８】比較例２で用いた脱塩水製造装置を示す系統図である。
【図９】比較例３で用いた脱塩水製造装置を示す系統図である。
【図１０】比較例４で用いた脱塩水製造装置を示す系統図である。
【符号の説明】
１前処理装置
２，２Ａ，２Ｂ，２Ｃ，２Ｄ，２Ｅ脱塩装置
３，３Ａ，３Ｂ，３ＫＲＯ膜分離装置
４，４Ａ，４Ｂ電気再生式脱塩装置
５ホウ素除去装置
６混床式イオン交換装置[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a demineralized water production apparatus, and more particularly to a demineralized water production apparatus capable of producing high-quality demineralized water with significantly reduced boron and TOC at a high water recovery rate.
[0002]
[Prior art]
  Conventionally, an ultrapure water production apparatus that produces ultrapure water from raw water such as city water, groundwater, and industrial water basically includes a pretreatment apparatus, a primary pure water production apparatus, and a secondary pure water production apparatus. . Among these, the pretreatment device is composed of agglomeration, levitation, filtration, a turbidity removal membrane device and the like. The primary pure water production apparatus is composed of one or more of activated carbon adsorption tower, ultraviolet (UV) oxidizer, chemical oxidizer, degasser, and the like, and a demineralizer. The desalinator is constituted by one or a combination of two or more of a reverse osmosis (RO) membrane separator, an electric regenerative desalinator, and an ion exchanger (mixed bed ion exchanger or ion-exchanged deionized water device). The The secondary pure water production apparatus is a combination of the same apparatus units as those of the primary pure water production apparatus. Generally, a low pressure UV oxidation apparatus, a mixed bed ion exchange apparatus, and an ultrafiltration (UF) ) Consists of a membrane separator.
[0003]
  In each of these units, the raw water is desalted by an RO membrane separation device, an electric regeneration type desalination device, and a mixed bed type ion exchange device. The removal of fine particles in the raw water is performed by the RO membrane separation device and the UF membrane separation device, and the removal of the TOC component is performed by the RO membrane separation device, the ion exchange pure water device, and the low pressure UV oxidation device.
[0004]
  When ultrapure water is produced using such ultrapure water production equipment using industrial water or other water as raw water, the purity of the obtained ultrapure water may be poor and the control value may not be satisfied. For example, in an ultrapure water production apparatus that produces ultrapure water having a resistivity of 18.24 MΩ · cm, the resistivity of the obtained ultrapure water may be reduced to 18.0 MΩ · cm or less. Such a decrease in purity is particularly noticeable when the operating time of the apparatus becomes long.
[0005]
  Thus, it is known that the cause of this purity decrease is boron in the raw water.
[0006]
  Conventionally, as a means for removing boron, a strongly basic anion exchange resin, a boron-selective chelate resin, or RO membrane separation treatment under alkaline conditions of pH 9 or higher is known. An ultrapure water production apparatus was proposed in which a boron adsorption resin tower filled with a boron-selective chelate resin was provided at the latter stage to remove boron (Japanese Patent Laid-Open No. 8-89956).
[0007]
  However, the strongly basic anion exchange resin has a small amount of boron adsorbed per unit resin amount and has poor boron removal efficiency. In RO membrane separation treatment, boron can be removed if it is alkaline at pH 9 or higher. However, in the pH neutral system, boron is present as boric acid without being dissociated as in the ultrapure water production process. Therefore, it cannot be removed and is concentrated in concentrated water.
[0008]
  The boron-selective chelate resin has a higher adsorption amount of boron per unit resin amount than a general strong base anion exchange resin, but the boron adsorption amount per unit resin amount is small when the boron concentration in the treated water is low. It becomes. For this reason, in the apparatus of JP-A-8-89956 in which a boron adsorbing resin tower is provided at the subsequent stage of the desalting apparatus, demineralized water having a low boron concentration is introduced into the boron adsorbing resin tower. There are disadvantages that the adsorption amount is small, the time during which water can be passed through the boron adsorption resin tower is short, and the boron adsorption resin tower needs to be regenerated frequently. That is, the boron concentration of city water, industrial water, etc., which is raw water, is usually about 20 μg / L. Therefore, the boron concentration of the treated water obtained by desalting the raw water having such a low boron concentration is further lower, and therefore the adsorption ability of the boron selective chelating resin cannot be effectively utilized.
[0009]
  In addition, the boron-selective chelate resin has a problem of elution of organic substances (TOC), and if the TOC is not removed by providing an RO membrane separator or UV oxidizer after the boron adsorption resin tower, the obtained super There is also a problem that the TOC of pure water is not stable. When the RO membrane separation device and the UV oxidation device are provided at the subsequent stage of the boron adsorption resin tower, there is a problem that the load on these devices is large.
[0010]
  By the way, in the RO membrane separation apparatus and the electric regeneration type desalination apparatus as the desalination apparatus, the concentrated water is circulated in order to increase the water recovery rate. In this case, for example, when the RO membrane separation device is arranged in series in two stages as the desalination device, or when the RO membrane separation device and the subsequent electric regeneration type desalination device are provided, the purity is relatively high. It is conceivable to return the concentrated water of the high-stage RO membrane separation apparatus or the electric regeneration type desalination apparatus to the introduction side of the front-stage RO membrane separation apparatus. However, when the concentrated water is recovered and circulated in this way, as described above, the RO membrane separation treatment at pH neutrality has a low boron removal rate of about 50 to 60%. Boron that could not be removed in the system is concentrated in the system, and the quality of the treated water is deteriorated over time.
[0011]
[Patent Document 1]
          JP-A-8-89956
[0012]
[Problems to be solved by the invention]
  The present invention aims to solve the above-mentioned conventional problems and to provide a demineralized water production apparatus capable of stably producing high-quality demineralized water with extremely low boron and TOC concentrations at a high water recovery rate. .
[0013]
[Means for Solving the Problems]
  The demineralized water production apparatus of the present invention (Claim 1) is supplied with boron-containing water and separates the boron-containing water into demineralized water and concentrated water, and concentrated water discharged from the demineralized apparatus. A demineralized water production apparatus having a return path for returning the upstream side of the demineralizer, and a boron removal apparatus for removing boron in the concentrated water provided in the middle of the return path,The boron removing device is a boron adsorption tower packed with a boron selective adsorbent,The desalination apparatus is constituted by a reverse osmosis membrane separation apparatus and / or an electric regeneration type desalination apparatus, and a reverse osmosis membrane separation apparatus for concentrated water treatment is provided in a return path between the desalination apparatus and the boron removal apparatus. Wherein the permeated water obtained by treating the concentrated water of the desalting apparatus with a reverse osmosis membrane separator for treating the concentrated water is introduced into the boron removing apparatus through the return path. To do.
  The demineralized water production apparatus of the present invention (Claim 2) is supplied with boron-containing water and separates the boron-containing water into demineralized water and concentrated water, and concentrated water discharged from the demineralized apparatus. A demineralized water production apparatus having a return path for returning the upstream side of the demineralizer, and a boron removal apparatus for removing boron in the concentrated water provided in the middle of the return path,The boron removing device is a boron adsorption tower packed with a boron selective adsorbent,The desalination apparatus includes a reverse osmosis membrane separation apparatus and an electric regeneration type desalination apparatus into which permeated water of the reverse osmosis membrane separation apparatus is introduced, and the concentrated water discharged from the electric regeneration type desalination apparatus And introduced into the boron removing apparatus through the return path.
  The demineralized water production apparatus of the present invention (Claim 3) is supplied with boron-containing water, and separates the boron-containing water into demineralized water and concentrated water, and concentrated water discharged from the demineralized apparatus. A demineralized water production apparatus having a return path for returning the upstream side of the demineralizer, and a boron removal apparatus for removing boron in the concentrated water provided in the middle of the return path,The boron removing device is a boron adsorption tower packed with a boron selective adsorbent,The desalinator comprises a preceding reverse osmosis membrane separation device and a subsequent reverse osmosis membrane separation device into which permeated water of the preceding reverse osmosis membrane separation device is introduced, and concentration of the subsequent reverse osmosis membrane separation device Water is introduced into the boron removing apparatus through the return path.
[0014]
  In the desalted water production apparatus of the present invention, the water recovery rate can be increased by circulating the concentrated water discharged from the desalting apparatus. Thus, when the concentrated water of the desalting apparatus is circulated, there is a problem of concentration of boron in the system as described above. In the present invention, this circulated concentrated water is treated with a boron removing apparatus to obtain boron. Then, the problem of boron concentration caused by circulating the concentrated water is solved. Moreover, in the present invention, since the concentrated water of the desalination apparatus having a relatively high boron concentration is processed by the boron removal apparatus, for example, in the treatment with a boron selective adsorbent such as a boron selective chelate resin, The amount of boron adsorbed increases, so that the amount of treated water can be increased (the water passage time can be increased), and the regeneration frequency of the adsorbent can be reduced.
[0015]
  Moreover, since TOC eluted from boron selective adsorbents such as boron selective chelating resin can be removed by a desalting apparatus, it is necessary to provide a device for removing TOC eluted from this boron selective adsorbent. In addition, an increase in the TOC of demineralized water can be prevented.
[0016]
  By the way, in the case where a boron adsorption resin tower is provided in the latter stage of the desalting apparatus as in the apparatus described in JP-A-8-89956, in addition to the problem of TOC elution from the boron selective chelate resin, There are also the following problems. That is, when a boron adsorption resin tower is provided in the desalination treatment system, interrupting water flow during resin regeneration will stop the production of desalted water. For this reason, it is necessary to provide two boron adsorption resin towers in order to perform continuous water passage during regeneration.
[0017]
  On the other hand, in the case of the demineralized water production apparatus of the present invention, at the time of regeneration or replacement of the boron adsorption resin tower, it is only necessary to interrupt the water flow and discharge the concentrated water out of the system. There is no need to provide two towers.
[0018]
  In addition, when processing concentrated water in this way, compared with the process in a desalination processing system | strain, the frequency of regeneration of a boron adsorption tower can be reduced by the amount of treated water being passed through a boron adsorption tower being small. You can also get the effect.
[0019]
  Further, when a boron adsorption resin tower is provided at the rear stage of the desalting apparatus as in the apparatus described in JP-A-8-89956, a booster pump is provided at the rear stage of the desalting apparatus, and the treatment of the desalting apparatus is performed. Although it may be necessary to pressurize the water and pass it through the boron adsorption resin tower, such a problem is solved when concentrated water is passed as in the present invention.
[0020]
  In the present invention, the desalination apparatus is constituted by an RO membrane separation apparatus and / or an electric regeneration type desalination apparatus.
(1) Desalination apparatus composed of an RO membrane separation device and an electric regeneration type desalination device into which permeate of the RO membrane separation device is introduced
Or
(2) Desalination apparatus composed of a front-stage RO membrane separator and a rear-stage RO membrane separator into which permeate from the front-stage RO membrane separator is introduced
Etc. can be adopted.
[0021]
  In addition, the electric regeneration type desalination apparatus has a plurality of anion exchange membranes and cation exchange membranes arranged alternately between electrodes (anode, cathode) to alternately form a concentration chamber and a desalination chamber. And an anion exchanger composed of an ion exchange resin, an ion exchange fiber or a graft exchanger, and a cation exchanger are mixed or filled in a multi-layered manner. Japanese Patent Publication No. 4-72567, Japanese Patent No. 2751090, Patent No. 2699256 and the like. The electric regenerative desalinator is equipped with H⁺Ion and OH⁻Ion exchange, which has been widely used for desalting treatment, is possible by generating ions and continuously regenerating the ion exchanger filled in the desalting chamber. There is an advantage that complete continuous water collection is possible without requiring a regeneration treatment using a chemical such as a resin device.
[0022]
  In such a desalted water production apparatus of the present invention, the concentrated water to be circulated is the concentrated water of the electrically regenerative desalinator in the subsequent stage of the RO membrane separator having a relatively high purity or the RO membrane separator in the subsequent stage. Is preferred.
[0023]
  When the concentrated water of the RO membrane separation device in the previous stage of the desalting apparatus is circulated, or when only one RO membrane separation device is provided as the desalting apparatus and the concentrated water is circulated, this concentrated water has a salt concentration. Therefore, if this is circulated to the desalting apparatus, the load on the desalting apparatus becomes too large, which is not preferable. Accordingly, in this case, an RO membrane separation device for desalting the concentrated water in the concentrated water return path (hereinafter, this RO membrane separation device may be referred to as “recovered RO membrane separation device”). It is preferable that the concentrated water is desalted by the recovered RO membrane separator, then boron is removed by the boron removing device, and then introduced into the desalting device.
[0024]
  When removing salts in concentrated water with this recovered RO membrane separator, if silica is concentrated in this concentrated water, silica scale may be generated in the recovered RO membrane separator, which may make desalting difficult. In addition, it is preferable to add a scale inhibitor to the concentrated water to be introduced into the recovered RO membrane separator or to adjust the conditions so that scales are difficult to be generated by adding an acid..
[0025]
DETAILED DESCRIPTION OF THE INVENTION
  Less thanEmbodiments of the desalinated water production apparatus of the present invention will be described below in detail with reference to the drawings.
[0026]
  1-6 is a system diagram showing an embodiment of the desalinated water production apparatus of the present invention.
[0027]
  The demineralized water production apparatus of FIG. 1 produces demineralized water by treating raw water with the pretreatment apparatus 1 and then treating with the desalination apparatus 2 comprising the RO membrane separation apparatus 3 and the electric regenerative demineralization apparatus 4. . The concentrated water of the RO membrane separation device 3 in the previous stage is discharged out of the system, and the permeated water of the RO membrane separation device 3 is processed by the electric regenerative desalination device 4 to obtain demineralized water, and the concentrated water is removed by boron. After supplying boron to the apparatus 5 and removing boron, the boron-treated water is returned to the inlet side of the RO membrane separation apparatus 3 and circulated.
[0028]
  The demineralized water production apparatus of FIG. 2 treats the raw water with the pretreatment apparatus 1 and then treats it with the demineralization apparatus 2A including the RO membrane separation apparatuses 3A and 3B and the electric regeneration type demineralization apparatus 4 arranged in two stages. It produces desalted water. Concentrated water from the upstream RO membrane separator 3A is discharged out of the system, and the permeated water from the RO membrane separator 3A is processed by the downstream RO membrane separator 3B. The permeated water from the RO membrane separator 3B is electrically regenerated. A desalted water is obtained by processing in the desalting apparatus 4. The concentrated water of the RO membrane separation device 3B in the latter stage and the concentrated water of the electric regenerative desalting device 4 are fed to the boron removing device 5 to remove boron, and then the boron treated water is introduced to the inlet side of the RO membrane separating device 3A. Return and cycle.
[0029]
  The demineralized water production apparatus of FIG. 3 produces demineralized water by treating the raw water with the pretreatment apparatus 1 and then treating with the demineralization apparatus 2B comprising the RO membrane separation apparatus 3 and the mixed bed ion exchange apparatus 6. is there. The permeated water of the upstream RO membrane separation device 3 is processed by the mixed bed type ion exchange device 6 to obtain demineralized water. The concentrated water of the RO membrane separation device 3 is treated by the recovered RO membrane separation device 3K, and the obtained permeate is fed to the boron removal device 5 to remove boron, and then the boron treated water is removed from the RO membrane separation device 3. Return to the inlet side and circulate. The concentrated water of the recovered RO membrane separation device 3K is discharged out of the system.
[0030]
  The demineralized water production apparatus of FIG. 4 treats raw water with the pretreatment apparatus 1 and then treats it with the RO membrane separation apparatus 3 and the demineralization apparatus 2C including the electric regeneration

type demineralization apparatuses

4A and 4B arranged in two stages. It produces desalted water. The concentrated water of the RO membrane separation device 3 is discharged out of the system, and the permeated water of this RO membrane separation device 3 is processed by the electric regeneration type desalination device 4A in the previous stage, and the permeated water of this electric regeneration type desalination device 4A is treated. Desalinated water is obtained by treatment with the electric regeneration type desalting apparatus 4B in the subsequent stage. The concentrated water of the first-stage electric regenerative desalting apparatus 4A and the concentrated water of the second-stage electric regenerating desalting apparatus 4B are fed to the boron removing apparatus 5 to remove boron, and then the boron treated water is removed from the RO membrane separation apparatus 3 Return to the inlet side of the circulator and circulate it.
[0031]
The demineralized water production apparatus of FIG. 5 is a desalting apparatus comprising the RO membrane separators 3A and 3B arranged in two stages and the electric regeneration

type desalinating apparatuses

4A and 4B arranged in two stages after the raw water is treated by the pretreatment apparatus 1. It is processed by the salt device 2D to produce demineralized water. The concentrated water of the upstream RO membrane separation device 3A is discharged out of the system, and the permeated water of this RO membrane separation device 3A is processed by the subsequent RO membrane separation device 3B. Treatment is performed with the regenerative desalting apparatus 4A, and the permeated water of the electric regenerating desalting apparatus 4A is treated with the subsequent electric regenerating desalting apparatus 4B to obtain desalted water. The concentrated water of the subsequent RO membrane separation device 3B and the concentrated water of the first and subsequent electric

regeneration desalination devices

4A and 4B are fed to the boron removing device 5 to remove boron, and then the boron-treated water is supplied to the RO membrane. It returns to the inlet side of the separation device 3A and circulates.
[0032]
  The demineralized water production apparatus of FIG. 6 treats raw water with the pretreatment apparatus 1 and then treats it with a demineralization apparatus 2E composed of RO membrane separation apparatuses 3A and 3B and a mixed bed ion exchange apparatus 6 arranged in two stages. It produces desalted water. The concentrated water of the upstream RO membrane separation device 3A is discharged out of the system, the permeated water of this RO membrane separation device 3A is processed by the subsequent RO membrane separation device 3B, and the permeated water of this RO membrane separation device 3B is mixed-bed. Demineralized water is obtained by treatment with a type ion exchanger 6. The concentrated water of the downstream RO membrane separation device 3B is fed to the boron removal device 5 to remove boron, and then the boron-treated water is returned to the inlet side of the RO membrane separation device 3A for circulation treatment.
[0033]
  In the present invention, as raw water, city water, industrial water, well water, other process waste water, or a mixed water thereof can be used. Generally, the boron concentration of these raw waters is in the range of 20-30 μg / L, but the present invention is applicable to raw water with a boron concentration of 1-500 μg / L.
[0034]
  There is no restriction | limiting in particular as the pre-processing apparatus 1, A turbidity apparatus, an activated carbon adsorption tower, a deaeration apparatus, a decarbonation apparatus etc. are used in combination as needed.
[0035]
  Any desalinator may be used as long as it includes a device that separates pretreated water into desalted water and concentrated water. Generally, an RO membrane separator and / or an electric regenerative desalinator are further required. Accordingly, an ion exchange device or the like is used. The desalination apparatus of the desalinized water production apparatus of the present invention is a combination of the RO membrane separation device 3 and the electric regeneration type desalination device 4 shown in FIG. 1, and the two-stage RO membrane separation devices 3A and 3B and the electric regeneration shown in FIG. A combination of the RO membrane separation device 3 and the mixed bed ion exchange device 6 shown in FIG. 3, the RO membrane separation device 3 shown in FIG. 4 and the two-stage electric regeneration

type desalination device

4A, 4B, the combination of the two-stage RO membrane separators 3A and 3B shown in FIG. 5 and the two-stage electric

regenerative desalinator

4A and 4B, and the two-stage RO membrane separators 3A and 3B shown in FIG. The combination with the ion exchange device 6 is not limited at all. For example,
(1)  One-stage treatment of RO membrane separator or electric regenerative desalinator
(2)  Multi-stage processing of RO membrane separators with two or more stages
(3)  RO membrane separator, electric regenerative desalinator and mixed bed ion exchanger
Etc. can also be adopted. In addition, in the two-stage treatment of the RO membrane separation apparatus, the pH adjustment is performed by adding an alkaline agent such as NaOH or KOH to the inlet water of the second-stage RO membrane separation apparatus for the purpose of ionizing the carbonic acid component. Can also be arbitrarily adopted. In addition, a non-regenerative ion exchange device may be used in combination. For example, in FIG. Further, a non-regenerative ion exchange device may be provided in place of the mixed bed ion exchange device 6 of FIG. Moreover, you may provide apparatuses other than desalination apparatuses, such as a deaeration apparatus, between the apparatus units which comprise these desalination apparatuses.
  In normal cases, the pH of the water to be treated in such a desalinator is in the range of 3-10.
[0036]
  In the demineralized water production apparatus of the present invention, in order to improve the water recovery rate, the concentrated water discharged from the demineralizer is circulated. In order to prevent the concentration of boron in the system by this circulatory treatment, The concentrated water is treated with a boron removing device 5 to remove boron.
[0037]
  In the present invention, in the case of a desalination apparatus in which the RO membrane separation apparatus and / or the electric regeneration type desalination apparatus are provided in two or more stages, the concentrated water to be circulated by removing boron is the former stage having a high salt concentration. The concentrated water of the apparatus is preferably discharged from the system and is the concentrated water of a later-stage electric regenerative desalination apparatus or RO membrane separation apparatus having a relatively high purity. For this reason, in the desalted water production apparatus of FIGS. 1 and 4, the concentrated water of the electric regeneration type desalination apparatus 4 or the electric regeneration

type desalination apparatuses

4A and 4B in the subsequent stage of the RO membrane separation apparatus 3 is circulated. In the desalted water production apparatuses 5 and 6, the concentrated water of the RO membrane separator 3B at the subsequent stage of the RO membrane separator 3A and the concentrated water of the electric regeneration-

type desalting apparatuses

4, 4A and 4B at the subsequent stage are circulated. In either case, the concentrated water from the preceding RO membrane separators 3 and 3A is discharged out of the system.
[0038]
  In the case of a desalination apparatus provided with only one stage of RO membrane separation apparatus or electric regeneration type desalination apparatus, or when it is necessary to circulate the concentrated water of the first stage RO membrane separation apparatus or electric regeneration type desalination apparatus As shown in FIG. 3, the recovered RO membrane separation device 3K for treating the concentrated water is provided in the concentrated water return system, and RO membrane separation treatment is performed, and the concentrated water is discharged out of the system. It is preferable to circulate the permeated water.
[0039]
  As shown in FIG. 3, when removing salt in the concentrated water with the recovered RO membrane separation device 3K, if silica is concentrated in the concentrated water, silica scale is generated in the recovered RO membrane separation device 3K, and desalting is performed. Since it may be difficult, it is preferable to add a scale inhibitor to the concentrated water to be introduced into the recovered RO membrane separator, or to adjust the conditions to make it difficult to generate a scale of about pH 4 by adding an acid.
[0040]
  The RO membrane separation treatment in the recovered RO membrane separation device 3K is a pH neutral or acidic condition. Under such pH conditions, boron is not ionized, and thus is not removed by the recovered RO membrane separation device 3K. To move on. In a normal case, the boron removal rate in the recovered RO membrane separation device 3K is about 20 to 30%. When such a recovery RO membrane separation device 3K is provided, the water recovery rate of the recovery RO membrane separation device 3K is preferably about 50 to 70%.
[0041]
  In addition, even in the demineralized water production apparatus of FIGS. 1 and 2 and FIGS. In general, it is preferable to discharge the concentrated water of the former RO membrane separation device out of the system.
[0042]
  In the present invention, the boron removing device 5 for treating the circulating concentrated water is, HoBoron adsorption packed with urinary selective adsorbentTowerUseThe
[0043]
  The boron selective adsorbent may be a granular material such as a boron selective chelate resin, or may be a fibrous material. Boron can be adsorbed and removed by filling these into an adsorption tower and passing circulating concentrated water. Further, boron may be removed by adding fine particles of a boron selective adsorbent to circulating concentrated water. However, when fine particles are used, a fine particle removal step is required in the latter stage, and in the case of an adsorption tower, the operation is easy, and the adsorption tower method is preferably adopted because it can be used repeatedly by regeneration. When the adsorption tower method is adopted, a single tower type or a multiple tower type such as a double tower type may be used. In the multi-column type, the adsorption towers may be used in series or in parallel. Further, the adsorption tower may be a regenerative type that is regenerated on the spot when regeneration is necessary, or may be a non-regenerative type that is replaced with a separately regenerated adsorption tower.
[0044]
  Examples of the boron selective adsorbent include those that adsorb boron by an ion exchange action and those that adsorb boron by a chelate action, and any of them can be used in the present invention. Note that a normal ion exchange resin having no boron selectivity is not preferable because it is a treatment of concentrated water and the coexisting salts quickly saturate the resin adsorption capacity and increase the regeneration frequency.
[0045]
  In the present invention, various boron-selective adsorbents can be used. For example, “Diaion CRB” (Mitsubishi Chemical Co., Ltd.), a commercially available boron-selective chelate resin, boron-selective chelate fiber “Kyrest Fiber GRY” (Kyrest Co., Ltd.) or the like can be used.
[0046]
  For example, “Diaion CRB02” has a chemical structure in which an N-glucamine group is introduced as a chelate-forming group having high boron selectivity into a styrene-divinylbenzene skeleton as shown below.
[0047]
[Chemical 1]

[0048]
This N-glucamine group is a tertiary amine type similar to the weakly basic anion exchange resin, and adsorbs boric acid boron by the following reaction.
[0049]
[Chemical 2]

[0050]
  There is no particular limitation on the flow SV of the concentrated water to the adsorption tower packed with the boron selective adsorbent. Boron-selective adsorbents that broke through and adsorbed boron are HCl, H₂SO₄It can be regenerated by an arbitrary method using an acid such as NaOH or an alkali agent such as NaOH or KOH.
[0051]
  On the other hand, as a chelating agent that forms a complex with boron, Tylon known as a liquid chelating agent: (OH)₂C₆H₂(SO₃Na)₂And sodium chromotropic acid: (OH)₂C₁₀H₄(SO₃Na)₂In addition, polyhydric alcohols such as sorbit and mannitol, curcumin, and the like can be used. When these chelating agents are added by making the concentrated water acidic at pH 5 or lower, a complex is formed with boron to trap boron. The complex formed is eliminated with a desalting apparatus.
[0052]
  In the present invention, since concentrated water having a high boron concentration is treated, as described above, the boron adsorption amount of a boron selective adsorbent such as a boron selective chelate resin can be increased. That is, the boron concentration of raw water such as industrial water is about 20 to 30 μg / L, and with such dilute water, the boron adsorption amount is low and the frequency of regeneration of the boron selective adsorbent is high. The boron concentration of the permeated water obtained by treating such raw water with the first-stage RO membrane separator is about 10 to 15 μg / L, and this permeated water is about 4 to 5 times with an electric regeneration type desalinator. The concentration of boron in concentrated water obtained by concentration treatment is about 80 μg / L.
[0053]
  Further, in the pH neutral treatment, the concentration of boron in the concentrated water of the first stage RO membrane separator is about 50-60 μg / L, and the permeated water obtained by treating this with the recovery RO membrane separator is recovered. Since the boron removal rate of the RO membrane separator is as low as about 20 to 30%, there is no significant difference from the boron concentration before processing, and it is about 50 to 60 μg / L.
[0054]
  In this way, by treating the concentrated water, water having a boron concentration of about 50 to 100 μg / L is introduced into the boron removing device 5, so that the boron adsorption amount per unit amount of the boron selective adsorbent can be reduced. Can be increased. In the case of raw water having a boron concentration of about 100 μg / L, such as city water in a hot spring area, concentrated water having a boron concentration of about 200 μg / L is introduced into the boron removing device 5.
[0055]
  In the present invention, the regeneration frequency of the boron selective adsorbent can also be obtained by treating the concentrated water, which is separated into the desalted water and the concentrated water by the desalting apparatus, and the amount of water is reduced with respect to the raw water, by the boron removing apparatus 5. Can be reduced.
[0056]
  BookThe demineralized water production apparatus of the invention is generally used by being incorporated in an ultrapure water production apparatus composed of a pretreatment apparatus as described above, a primary pure water production apparatus, and a secondary pure water production apparatus. In addition to the desalting apparatus and the boron removing apparatus shown in FIGS. 1 to 6, an arbitrary processing apparatus may be provided at the front stage or the rear stage.
[0057]
【Example】
  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. For convenience of explanation, a comparative example is given first.
[0058]
  Comparative Example 1
  Demineralized water was produced using the demineralized water production apparatus shown in FIG.
[0059]
  The raw water is Nogicho water (pH: 6.9, conductivity: 13.0 mS / m, boron concentration: 21 to 25 μg / L), and this raw water is subjected to microfiltration (MF) membrane separation as the pretreatment device 1 After filtering with a device (pore diameter: 0.2 μm), decarboxylation treatment is performed in a decarboxylation tower (inlet pH: 5 to 5.5), and pretreatment water (pH: 5.8 to 6.2, conductivity: 14.4 mS / m, boron concentration: 21 to 25 μg / L).
[0060]
  This pretreated water is passed through the RO membrane separator (“ES20” 4 inch, 2 pieces manufactured by NIPPON DENKO CO., LTD.) 3 at a pressure of 0.8 MPa and treated under the following conditions, and the concentrated water is discharged out of the system. did. The permeated water of the RO membrane separator 3 is passed through an electric regenerative desalinator (one "M40 type" manufactured by Kurita Kogyo Co., Ltd.) 4 and treated under the following conditions to obtain desalted water, and concentrated water is used as the system. Discharged outside.
[Processing conditions of RO membrane separator 3]
    Water recovery rate: 75%
    Water supply amount: 444L / hr
    Treated water (permeated water) amount: 333 L / hr
[Processing conditions of the electric regenerative desalination apparatus 4]
    Water recovery rate: 90%
    Amount of treated water (demineralized water): 300 L / hr
    Concentrated water volume: 33 L / hr
[0061]
  In this treatment, the boron concentration of the treated water (permeated water: RO treated water) of the RO membrane separation device 3, the boron concentration and the TOC concentration of demineralized water (treated water of the electric regeneration type desalting device 4), and the water of the entire system The recovery rate was as shown in Table 1.
[0062]
  Comparative Example 2
  The demineralized water production apparatus shown in FIG. 8 is the same as in Comparative Example 1 except that the concentrated water of the electric regeneration type demineralizer 4 is directly returned to the inlet side of the RO membrane separator 3 and circulated. Table 1 shows the boron concentration of RO-treated water, the boron concentration and TOC concentration of desalted water, and the water recovery rate of the entire system.
[0063]
  In Comparative Example 2, the water recovery rate was higher than that of Comparative Example 1 because the concentrated water of the electric regeneration type desalination apparatus 4 was circulated. However, the boron concentration in the RO treated water and the desalted water was increased by the concentration of boron by the circulatory process. Is high.
[0064]
  Example 1
  In the comparative example 2, the demineralized water production apparatus of the present invention shown in FIG. 1 is provided with a boron removing device 5 in the return path of the concentrated water of the electric regenerative demineralizer 4, and the concentrated water of the electric regenerative demineralizer 4 is supplied. Demineralized water was produced in the same manner except that the boron removal process was performed by the boron removal apparatus 5 and then returned to the inlet side of the RO membrane separation apparatus 3.
[0065]
  The boron removing device 5 used is a boron adsorbing resin tower packed with 3.3 L of a boron selective chelating resin “Diaion CRB02” manufactured by Mitsubishi Chemical Corporation. An electric regeneration type desalting apparatus 4 is added to the boron adsorbing resin tower. Of concentrated water (boron concentration of feed water: 130-150 μg / L): SV: 10 hr^-1The water was passed through and treated.
[0066]
  The boron concentration of RO treated water, the boron concentration and TOC concentration of desalted water, and the water recovery rate of the entire system are as shown in Table 1. Although the water recovery rate was increased by circulating treatment of concentrated water, In addition, high-quality demineralized water with low boron and TOC concentrations could be obtained.
[0067]
  Since this boron adsorption resin tower broke through in 1060 hours of water flow, it was regenerated once in 1060 hours of water flow.
[0068]
  Comparative Example 3
  9, the same boron-adsorbing resin tower (boron selectivity) as used in Example 1 between RO membrane separation device 3 and electric regeneration type desalting device 4 in Comparative Example 2 was obtained. The amount of chelate resin is 3.3 L, the same amount as in Example 1, and the water flow SV is 100 hr.^-1, The water supply amount is 333 L / hr), the permeated water of the RO membrane separation device 3 is treated with a boron adsorption resin tower and then passed through the electric regeneration demineralizer 4 to obtain demineralized water. Demineralized water was produced in the same manner except that the concentrated water of the salt device 4 was returned to the inlet side of the RO membrane separation device 3 and circulated.
[0069]
  At this time, the boron concentration of the RO treated water, the boron concentration and TOC concentration of the desalted water, and the water recovery rate of the entire system are as shown in Table 1. The recovery rate is high, and since the boron adsorption resin tower is provided between the RO membrane separation device 3 and the electric regeneration type desalting device 4, the boron concentration in the desalted water is low, but the TOC concentration is high. This increase in TOC concentration is attributed to the elution of TOC from the boron selective chelating resin.
[0070]
  Moreover, since the boron concentration of the RO treatment water which is the feed water of the boron adsorption resin tower is 15 to 17 μg / L, and this boron adsorption resin tower broke through with water passing through 640 hr, it is regenerated once in the water passing through 640 hr. It was necessary and reproduction frequency was high.
[0071]
  Moreover, in this way, Comparative Example 3 in which the boron adsorption resin tower is provided in the desalting treatment system is industrially disadvantageous from the following points. That is, when the concentrated water is passed through the boron adsorption resin tower as in Example 1, it is sufficient to interrupt the water flow and discharge the concentrated water out of the system when the boron adsorption resin tower is regenerated. Since the flow of water in the treatment system cannot be interrupted, two boron adsorption resin towers are required in order to continuously pass water during regeneration of the boron adsorption resin tower.
[0072]
  Comparative Example 4
  By using the desalted water production apparatus shown in FIG. 10, in Comparative Example 1, a boron adsorption resin tower similar to that used in Example 1 after the electric regeneration type desalting apparatus 4 (the amount of the boron-selective chelate resin is Example 1). The same amount of 3, 3L, water flow SV is 91hr^-1The water supply amount was 300 L / hr), and the desalted water was produced in the same manner except that the treated water of the electric regeneration type desalting apparatus 4 was treated with a boron adsorption resin tower. Concentrated water was not circulated.
[0073]
  At this time, the boron concentration of RO treated water, the boron concentration and TOC concentration of desalted water, and the water recovery rate of the entire system are as shown in Table 1, and the water recovery rate is low because the circulating treatment of concentrated water is not performed. Since the treated water of the electric regeneration type desalinization apparatus 4 was further treated with the boron adsorption resin tower, the boron concentration of the desalted water is low, but the TOC concentration is high due to the elution of the TOC from the boron selective chelate resin. A processing device is required, and the load on the TOC removing device is large, so that the size of the device increases.
[0074]
  The boron concentration of the feed water of the boron adsorption resin tower of this comparative example (treated water of the electric regeneration type desalination apparatus) is 4 to 6 μg / L. Since this boron adsorption resin tower broke through in 1847 hours of water flow, 1847 hours of water flow Therefore, it was necessary to perform the reproduction at a frequency of once. This regeneration frequency is the lowest in Example 1 and Comparative Examples 3 and 4 using the boron adsorption resin tower. However, the provision of the boron adsorption resin tower in the desalting treatment system in this way is the above Comparative Example 3 In addition to the disadvantage that two boron adsorbing resin towers are required for the regeneration of the boron adsorbing resin tower, the provision of the boron adsorbing resin tower in the subsequent stage of the electric regeneration type desalting apparatus 4 , It is not preferable not only from the elution of TOC but also from the following points.
[0075]
  That is, since a load of a back pressure of 0.1 MPa or more is generated in the subsequent stage of the electric regeneration type desalination apparatus 4 and the water supply limit pressure is often about 0.4 MPa, the water supplied to the boron adsorption resin tower depends on the water supply distance. In order to increase the pressure, a booster pump may be required after the electric regenerative desalinator 4.
[0076]
[Table 1]

[0077]
【The invention's effect】
  Less thanAs described in detail above, according to the demineralized water production apparatus of the present invention, high-quality demineralized water having extremely low boron and TOC concentrations can be stably produced with a high water recovery rate. Moreover, according to the present invention, the boron adsorption amount per unit amount of the boron selective adsorbent used for removing boron can be increased, and the regeneration frequency can be reduced by effectively utilizing the boron selective adsorbent. .
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a demineralized water production apparatus of the present invention.
FIG. 2 is a system diagram showing another embodiment of the demineralized water production apparatus of the present invention.
FIG. 3 is a system diagram showing another embodiment of the demineralized water production apparatus of the present invention.
FIG. 4 is a system diagram showing another embodiment of the demineralized water production apparatus of the present invention.
FIG. 5 is a system diagram showing another embodiment of the demineralized water production apparatus of the present invention.
FIG. 6 is a system diagram showing another embodiment of the demineralized water production apparatus of the present invention.
7 is a system diagram showing a desalted water production apparatus used in Comparative Example 1. FIG.
FIG. 8 is a system diagram showing a demineralized water production apparatus used in Comparative Example 2.
9 is a system diagram showing a desalinated water production apparatus used in Comparative Example 3. FIG.
FIG. 10 is a system diagram showing a demineralized water production apparatus used in Comparative Example 4..
[Explanation of symbols]
  1 Pretreatment device
  2,2A, 2B, 2C, 2D, 2E Desalination equipment
  3,3A, 3B, 3K RO membrane separator
  4,4A, 4B Electric regenerative desalination equipment
  5 Boron remover
  6 Mixed bed type ion exchanger

Claims

ホウ素含有水が供給され、該ホウ素含有水を脱塩水と濃縮水とに分離する脱塩装置と、
該脱塩装置から排出される濃縮水を、該脱塩装置の上流側に戻す返送路と、
該返送路の途中に設けられ、該濃縮水中のホウ素を除去するホウ素除去装置とを有する脱塩水製造装置であって、
前記ホウ素除去装置は、ホウ素選択性吸着体を充填したホウ素吸着塔であり、
該脱塩装置は、逆浸透膜分離装置及び／又は電気再生式脱塩装置により構成され、
該脱塩装置とホウ素除去装置との間の返送路に濃縮水処理用の逆浸透膜分離装置が設けられており、前記脱塩装置の濃縮水を該濃縮水処理用の逆浸透膜分離装置で処理して得られた透過水が前記返送路を通して前記ホウ素除去装置に導入されることを特徴とする脱塩水製造装置。A demineralizer which is supplied with boron-containing water and separates the boron-containing water into demineralized water and concentrated water;
A return path for returning the concentrated water discharged from the demineralizer to the upstream side of the demineralizer;
A demineralized water production apparatus having a boron removal apparatus that is provided in the middle of the return path and removes boron in the concentrated water,
The boron removing device is a boron adsorption tower packed with a boron selective adsorbent,
The desalination apparatus is constituted by a reverse osmosis membrane separation apparatus and / or an electric regeneration type desalination apparatus,
A reverse osmosis membrane separation device for concentrated water treatment is provided in a return path between the desalting device and boron removal device, and the concentrated water of the desalination device is used as a reverse osmosis membrane separation device for the concentrated water treatment. The demineralized water production apparatus is characterized in that the permeated water obtained by the treatment is introduced into the boron removing apparatus through the return path.

ホウ素含有水が供給され、該ホウ素含有水を脱塩水と濃縮水とに分離する脱塩装置と、
該脱塩装置から排出される濃縮水を、該脱塩装置の上流側に戻す返送路と、
該返送路の途中に設けられ、該濃縮水中のホウ素を除去するホウ素除去装置とを有する脱塩水製造装置であって、
前記ホウ素除去装置は、ホウ素選択性吸着体を充填したホウ素吸着塔であり、
該脱塩装置は、逆浸透膜分離装置と、該逆浸透膜分離装置の透過水が導入される電気再生式脱塩装置とを備え、
該電気再生式脱塩装置から排出される濃縮水が、前記返送路を経て前記ホウ素除去装置に導入されることを特徴とする脱塩水製造装置。A demineralizer which is supplied with boron-containing water and separates the boron-containing water into demineralized water and concentrated water;
A return path for returning the concentrated water discharged from the demineralizer to the upstream side of the demineralizer;
A demineralized water production apparatus having a boron removal apparatus that is provided in the middle of the return path and removes boron in the concentrated water,
The boron removing device is a boron adsorption tower packed with a boron selective adsorbent,
The desalination apparatus includes a reverse osmosis membrane separation device and an electric regeneration type desalination device into which permeated water of the reverse osmosis membrane separation device is introduced,
Concentrated water discharged from the electric regenerative demineralizer is introduced into the boron removing apparatus via the return path.

ホウ素含有水が供給され、該ホウ素含有水を脱塩水と濃縮水とに分離する脱塩装置と、
該脱塩装置から排出される濃縮水を、該脱塩装置の上流側に戻す返送路と、
該返送路の途中に設けられ、該濃縮水中のホウ素を除去するホウ素除去装置とを有する脱塩水製造装置であって、
前記ホウ素除去装置は、ホウ素選択性吸着体を充填したホウ素吸着塔であり、
前記脱塩装置が前段の逆浸透膜分離装置と、該前段の逆浸透膜分離装置の透過水が導入される後段の逆浸透膜分離装置とを備え、該後段の逆浸透膜分離装置の濃縮水が前記返送路を経て前記ホウ素除去装置に導入されることを特徴とする脱塩水製造装置。A demineralizer which is supplied with boron-containing water and separates the boron-containing water into demineralized water and concentrated water;
A return path for returning the concentrated water discharged from the demineralizer to the upstream side of the demineralizer;
A demineralized water production apparatus having a boron removal apparatus that is provided in the middle of the return path and removes boron in the concentrated water,
The boron removing device is a boron adsorption tower packed with a boron selective adsorbent,
The desalinator comprises a preceding reverse osmosis membrane separation device and a subsequent reverse osmosis membrane separation device into which permeated water of the preceding reverse osmosis membrane separation device is introduced, and concentration of the subsequent reverse osmosis membrane separation device Water is introduced into the boron removing device through the return path, and the desalinated water producing device.