JP4066348B2

JP4066348B2 - Virus removal method and apparatus

Info

Publication number: JP4066348B2
Application number: JP2003046831A
Authority: JP
Inventors: 清和武村; 一彦能登; 那夫紀大熊
Original assignee: Hitachi Plant Technologies Ltd
Current assignee: Hitachi Plant Technologies Ltd
Priority date: 2003-02-25
Filing date: 2003-02-25
Publication date: 2008-03-26
Anticipated expiration: 2023-02-25
Also published as: CN1323037C; CN1524804A; JP2004255250A

Description

【０００１】
【発明の属する技術分野】
本発明は、ウイルス除去方法及び装置に係り、特に下水道、湖沼水、河川水、プール水等の水中に存在するウイルスを膜濾過によって濾過することで、水中からウイルスを除去するウイルスの除去方法及び装置に関する。
【０００２】
【従来技術】
下水道、湖沼水、河川水、水槽等の水中には多数種のウイルスが存在することが分かってきたが、多数種のウイルスの中には人や家畜等に害を与えるものもあり、水中のウイルスを除去又は不活性化することが必要になってきている。
【０００３】
水中に生息するウイルスを除去又は不活性化する従来の一般的な方法として、ウイルスが存在する水を塩素処理する方法、オゾン処理する方法、紫外線を照射する方法、加熱する方法等がある。
【０００４】
これら以外にも、特許文献１には、膜口目の繊毛虫が存在する領域に繊毛虫を生息させるための直径５０〜５００μｍの多孔性担体を備え、この領域にウイルスが存在する水を通過させることにより、ウイルスを繊毛虫に取り込ませて除去する方法が開示されている。更に、特許文献２には、材料表面にアミン化合物を固定化した有機材料を膜としたウイルスの選択的除去材料が開示されている。
【０００５】
しかし、塩素処理は残留塩素の問題、オゾン処理や紫外線照射処理は処理コストの問題、加熱処理は耐熱ウイルスには適用できないと共に下水道等の大量の水の処理には不向きであるとの問題がある。また、特許文献１は膜口目の繊毛虫を必要とすると共に、繊毛虫へのウイルスの取り込みのバラツキにより完全なウイルスの除去は難しいという欠点がある。特許文献２は、血漿中や血液成分を含んだ蛋白溶液から選択的にウイルスを除去する医薬品業界等での使用を目的としたもので、下水道等の大量の水からウイルスを除去するには不向きである。
【０００６】
【特許文献１】
特開平１０−１３７７８３号公報
【０００７】
【特許文献２】
特開平６−１１４２５０号公報
【０００８】
【発明が解決しようとする課題】
ところで、下水道等の汚水からウイルスを除去する方法として、膜濾過法が着目されている。この膜濾過法は、薬品の残留、処理コストの問題、耐熱ウイルスの問題等がない上に、水の浄化も合わせて行えるので、下水道等の汚水からウイルスを除去するのに適している。
【０００９】
しかしながら、この膜濾過法は、水中からウイルスを完全に除去するには、ウイルスの大きさよりも小さな孔径の膜を使用しなくてはならないため膜の透過流束が低下するので、下水道等の大量の水を処理する上で処理効率が悪いという欠点がある。
【００１０】
本発明はかかる問題に鑑みて成されたもので、膜の透過流束を低下させることなく水中のウイルスを完全に除去することのできるウイルス除去方法及び装置を提供することを目的とする。
【００１１】
【課題を解決するための手段】
本発明の発明者は、水中に存在するウイルスはＳＳ成分に吸着され易く、ＳＳ成分に吸着されることにより、見かけ上の径が大きくなるので、ウイルスよりも大きな公称孔径の膜であってもウイルスを膜濾過できるとの知見を得た。更には、ウイルスよりも大きな膜の公称孔径と処理槽内のＳＳ成分濃度との相互の関係を適切にコントロールすることで、膜の透過流束を低下させることなく水中のウイルスを完全に除去できるとの知見も得た。本発明はかかる知見に基づいて成されたものである。
【００１２】
本発明の請求項１は前記目的を達成するために、処理槽内の被処理水中に膜濾過器を浸漬させて、前記被処理水中に存在するウイルスを膜濾過により除去するウイルス除去方法において、前記被処理水から除去したいウイルスの大きさよりも大きな公称孔径の膜に設定するとともに、前記被処理水のＳＳ成分濃度を測定し、前記膜の公称孔径が前記ウイルスの大きさと略同等の０．０１μｍ以下の膜濾過器を使用するときには、前記測定したＳＳ成分濃度が０ｍｇ／Ｌを超えて、５００ｍｇ／Ｌ未満になるように前記被処理水のＳＳ成分濃度をコントロールし、前記膜の公称孔径が０．０１μｍを超えて０．１μｍ以下の膜濾過器を使用するときには、前記測定したＳＳ成分濃度が５００ｍｇ／Ｌ以上、３０００ｍｇ／Ｌ未満になるように前記被処理水のＳＳ成分濃度をコントロールし、前記膜の公称孔径が０．１μｍを超えて０．８μｍ以下の膜濾過器を使用するときには、前記測定したＳＳ成分濃度が３０００ｍｇ／Ｌ以上になるように前記被処理水のＳＳ成分濃度をコントロールすることを特徴とする。
【００１３】
本発明の請求項１によれば、膜の公称孔径を被処理水から除去したいウイルスの大きさよりも大きく設定すると共に、膜濾過器に使用する膜の公称孔径に応じて被処理水のＳＳ成分濃度をコントロールするようにしたので、膜の透過流束を低下させることなく被処理水中のウイルスを完全に除去することができる。
【００１４】
本発明の請求項２は前記目的を達成するために、処理槽内の被処理水中に膜濾過器を浸漬させて、前記被処理水中に存在するウイルスを膜濾過により除去するウイルス除去方法において、前記被処理水から除去したいウイルスの大きさよりも大きな公称孔径の膜に設定するとともに、前記被処理水のＳＳ成分濃度を測定し、前記測定したＳＳ成分濃度が０ｍｇ／Ｌを超えて、５００ｍｇ／Ｌ未満のときには、前記膜濾過器に使用する膜の公称孔径を、前記ウイルスの大きさと略同等の０．０１μｍ以下にコントロールし、前記測定したＳＳ成分濃度が５００ｍｇ／Ｌ以上、３０００ｍｇ／Ｌ未満のときには、前記膜濾過器に使用する膜の公称孔径を、０．０１μｍを超えて０．１μｍ以下にコントロールし、前記測定したＳＳ成分濃度が３０００ｍｇ／Ｌ以上のときには、前記膜濾過器に使用する膜の公称孔径を、０．１μｍを超えて０．８μｍ以下にコントロールすることを特徴とする。
【００１５】
また、本発明の請求項２によれば、膜の公称孔径を被処理水から除去したいウイルスの大きさよりも大きく設定すると共に、被処理水のＳＳ成分濃度に応じて前記膜濾過器に使用する膜の公称孔径をコントロール（管理）するようにしたので、膜の透過流束を低下させることなく被処理水中のウイルスを完全に除去することができる。
【００１６】
ここで、本発明におけるＳＳ成分とは、水中に浮遊する固形分全般を意味し、本発明を活性汚泥処理装置に適用した場合には、ＳＳ成分の主たる成分は活性汚泥になる。
【００１８】
これは、請求項１での膜濾過器に使用する膜の公称孔径に応じて被処理水のＳＳ成分濃度をコントロールする場合、又は請求項２での被処理水のＳＳ成分濃度に応じて前記膜濾過器に使用する膜の公称孔径をコントロールする場合に、膜の透過流束を低下させることなく水中のウイルスを完全に除去するための膜の公称孔径とＳＳ成分濃度との相互の関係を示したものである。この場合、膜の公称孔径が０．０１μｍ以下のときに被処理水のＳＳ成分濃度が５００ｍｇ／Ｌを超える関係の場合、ウイルスの除去はできるが、膜の透過流束が急速に低下するので良くない。
【００２０】
これは、請求項１において、膜の公称孔径が０．０１μｍを超えて０．１μｍ以下の膜濾過器を使用する場合には、被処理水のＳＳ成分濃度を５００ｍｇ／Ｌ以上、３０００ｍｇ／Ｌ未満にコントロールすることで、膜の透過流束を低下させることなく水中のウイルスを完全に除去することができる。一方、請求項２において、被処理水のＳＳ成分濃度が５００ｍｇ／Ｌ以上、３０００ｍｇ／Ｌ未満の場合には、膜濾過器に使用する膜の公称孔径を０．０１μｍを超えて０．１μｍ以下にコントロール（管理）することで、膜の透過流束を低下させることなく水中のウイルスを完全に除去することができる。
【００２２】
これは、請求項１において、膜の公称孔径が０．１μｍを超えて０．８μｍ以下の膜濾過器を使用する場合には、被処理水のＳＳ成分濃度を３０００ｍｇ／Ｌ以上にコントロールすることで、膜の透過流束を低下させることなく水中のウイルスを完全に除去することができる。尚、ＳＳ成分濃度を３０００ｍｇ／Ｌを超えていたずらに大きくすると、膜が目詰まりし易くなり、目詰まりの観点からＳＳ成分濃度の上限は２００００ｍｇ／Ｌ程度が好ましい。また、請求項２において、被処理水のＳＳ成分濃度が３０００ｍｇ／Ｌ以上の場合には、膜濾過器に使用する膜の公称孔径を０．１μｍを超えて０．８μｍ以下にコントロール（管理）することで、膜の透過流束を低下させることなく水中のウイルスを完全に除去することができる。
【００２３】
本発明の請求項３は請求項１において、前記処理槽は活性汚泥処理槽であると共に、前記活性汚泥処理槽からの汚泥引き抜き量又は引き抜いた汚泥を濃縮して前記活性汚泥処理槽に返送する汚泥返送量を調整することにより、前記被処理水のＳＳ成分濃度をコントロールすることを特徴とする
【００２４】
これは、本発明のウイルス除去方法は、下水道等の汚水処理に一般的に使用されている活性汚泥処理法に最適な方法であり、被処理水のＳＳ成分濃度の制御に活性汚泥の引き抜きと濃縮汚泥の返送によって簡単に達成することが可能である。即ち、処理槽に設置した膜濾過器の膜の公称孔径に対して、被処理水のＳＳ成分濃度が低すぎてウイルスの除去能力が低下する場合には、引き抜いた汚泥を脱水等により濃縮して処理槽に戻してやる。逆に、被処理水のＳＳ成分濃度が高すぎて膜の透過流束が低下する場合には、汚泥の引き抜き量を多くする。
【００２５】
本発明の請求項４は請求項１〜３の何れか１において、前記処理槽内に活性炭、ゼオライト、多孔性担体、凝集材の添加物のうちの少なくとも１つを添加することを特徴とする。
【００２６】
これにより、ＳＳ成分同士の吸着や凝集を促進すると共に、ＳＳ成分の主成分である活性汚泥の可溶化を防止できるので、ウイルスの膜濾過性能を更に向上させることができる。
【００２９】
本発明の請求項５は前記目的を達成するために、被処理水中に存在するウイルスを膜濾過により除去するウイルス除去装置において、前記被処理水から除去したいウイルスの大きさよりも大きな公称孔径の膜であって前記ウイルスの大きさと略同等の０．０１μｍ以下の膜濾過器を前記被処理水中に浸漬させた第１の処理槽と、膜の公称孔径が０．０１μｍを超えて０．１μｍ以下の膜濾過器を前記被処理水中に浸漬させた第２の処理槽と、膜の公称孔径が０．１μｍを超えて０．８μｍ以下の膜濾過器を前記被処理水中に浸漬させた第３の処理槽と、前記被処理水の流入を前記第１〜第３の処理槽の何れかに切り換える切り換え手段と、前記流入する被処理水のＳＳ成分濃度を測定する測定手段と、前記測定手段の測定結果に基づいて前記切り換え手段を制御するコントローラと、を備えたことを特徴とする。
【００３０】
本発明の請求項５は、請求項２の本発明のウイルス除去方法を具体的な装置として構成したものである。
【００３１】
本発明の請求項６は請求項５において、活性炭、ゼオライト、多孔性担体、凝集材の添加物のうちの少なくとも１つを前記処理槽内に添加する添加手段を設けたことを特徴とする。
【００３２】
【発明の実施の形態】
以下添付図面に従って、本発明に係るウイルス除去方法及び装置の好ましい実施の形態について詳説する。
【００３３】
本発明を説明する前に、表１により本発明の理論的な根拠を説明する。
【００３４】
表１は、膜濾過器の膜の公称孔径と試験水のＳＳ成分濃度によるウイルスの膜濾過効果との関係を示した実験結果であり、０．０１μｍ未満の大きさのウイルスが存在する試験水のＳＳ成分濃度を増加させていったときに、公称孔径が何μｍの膜であれば、ウイルスを完全に除去でき且つ膜の透過流束を維持することができるかを調べたものである。ＳＳ成分としては本発明を活性汚泥処理装置に適用することを想定して活性汚泥を使用し、試験水中の活性汚泥濃度（ＭＬＳＳ）を変化させた。
【００３５】
【表１】

その結果、表１から分かるように、ＭＬＳＳが０ｍｇ／Ｌを超えて５００ｍｇ／Ｌ未満の範囲では、ウイルスの大きさと公称孔径が略同等の０．０１μｍ以下の膜を使用することにより、ウイルスを完全に除去でき且つ膜の透過流束を維持することができた。ＭＬＳＳを大きくしていって、ＭＬＳＳが５００ｍｇ／Ｌ以上、３０００ｍｇ／Ｌ未満の範囲では、公称孔径が０．０１μｍ以上、０．１μｍ未満の範囲の膜を使用することにより、ウイルスを完全に除去でき且つ膜の透過流束を維持することができた。ＭＬＳＳを更に大きくして３０００ｍｇ／Ｌ以上にすると、公称孔径が０．１μｍ以上、０．８μｍ未満の範囲の膜を使用することにより、ウイルスを完全に除去でき且つ膜の透過流束を維持することができた。このように、試験水中のＳＳ成分濃度を大きくすることで、ウイルスの大きさよりも大きな公称孔径の膜でウイルスを濾過できる理由は、試験水中に存在するウイルスはＳＳ成分に吸着され、ＳＳ成分に吸着されることにより、見かけ上の径が大きくなるためであると考察される。また、ウイルスの膜濾過において、被処理水に活性炭、ゼオライト、多孔性担体、凝集材等のＳＳ成分同士の吸着や凝集を促進する添加物のうちの少なくとも１つを添加することが好ましい。これは、ＳＳ成分濃度が小さくても添加物により、ウイルスを吸着したＳＳ成分の吸着性を良くするので、見かけ上の大きさを大きくすることができる。また、ＳＳ成分濃度が濃い場合には、ＳＳ成分の主成分である活性汚泥の可溶化現象が生じ易く、ウイルスが再分散し易いが、上記の添加物を添加することで活性汚泥の可溶化現象を抑制することができる。
【００３６】
本発明はかかる知見に基づいてウイルス除去方法及び装置を構成したものである。
【００３７】
図１は、本発明のウイルス除去装置を、アンモニア性廃水（以下「廃水」という）の窒素除去を行う活性汚泥処理装置１０に適用した例であり、膜濾過器に使用する膜の公称孔径に応じて廃水のＳＳ成分濃度をコントロールする第１の実施の形態である。
【００３８】
活性汚泥処理装置１０において、廃水は原水配管１２から生物処理槽１４に流入する。生物処理槽１４は脱窒槽１６と硝化槽１８とに区画され、硝化槽１８の液は循環配管２０を介して脱窒槽１６に循環される。硝化槽１８では、ブロア２２に接続された曝気配管２４からエアが曝気され、廃水と活性汚泥とが好気性条件で接触して、廃水中のアンモニア性窒素が硝酸性窒素に硝化処理される。一方、脱窒槽１６では、硝化槽１８で硝化処理により生成されて循環配管２０により循環された硝酸性窒素が嫌気性条件下で窒素ガスに脱窒処理される。
【００３９】
また、硝化槽１８内の廃水中には、膜濾過器２６が浸漬され、膜濾過器２６は処理水配管２８に接続されると共に、処理水配管２８には吸引ポンプ３０が配設される。これにより、硝化槽１８内の液が膜濾過器２６の膜によって吸引濾過され、処理水と活性汚泥とに分離され、処理水は処理水配管２８を介して系外に排出される。かかる膜濾過によって、廃水中に存在するウイルスも除去される。
【００４０】
本発明では、膜濾過器２６に使用する膜の公称孔径は除去したいウイルスの大きさよりも大きく設定される。更に、硝化槽１８内には、硝化槽１８内の廃水のＳＳ成分濃度を測定する、例えば濁度計等のＳＳ濃度センサ３２が設けられると共に、ＳＳ濃度センサ３２で測定された測定結果はコントローラ３４に入力される。硝化槽１８の底部からは汚泥ポンプ３６を備えた汚泥排出管３８が延設され切換器４０に接続されると共に、排出された汚泥の流れが切換器４０によって余剰汚泥管４２と汚泥返送管４４とに切り換えられる。この場合、汚泥返送管４４による汚泥の返送先を硝化槽１８にしても、脱窒槽１６にしてもよい。そして、コントローラ３４は、ＳＳ濃度センサ３２で測定された測定結果に基づいて余剰汚泥管４２と汚泥返送管４４との何れかに切換器４０で切り換える。汚泥返送管４４の途中には汚泥濃度を濃縮する、例えば脱水器等の汚泥濃縮器４６が設けられ、濃縮程度はコントローラ３４によって制御される。
【００４１】
また、硝化槽１８の上方には、添加物タンク４８が設けられ、添加物タンク４８には、活性炭、ゼオライト、多孔性担体、凝集材の添加物のうちの少なくとも１つが貯留される。添加物タンク４８から硝化槽１８に添加配管５０が延設されると共に、添加配管５０には添加物の添加量を調整する調整バルブ５２が設けられる。
【００４２】
次に、上記の如く構成された第１の実施の形態の活性汚泥処理装置１０で廃水中に存在するウイルスを除去するウイルスの除去方法を説明する。
【００４３】
硝化槽１８に浸漬された膜濾過器２６に使用した膜の公称孔径が０．０１μｍ以下の場合には、硝化槽１８内の廃水のＳＳ成分濃度が０ｍｇ／Ｌを超えて、５００ｍｇ／Ｌ未満の範囲に維持されるようにコントロールする。即ち、コントローラ３４は、ＳＳ濃度センサ３２によって測定される廃水のＳＳ成分濃度が５００ｍｇ／Ｌを超えた場合には、汚泥ポンプ３６を運転すると共に、切換器４０を余剰汚泥管４２側に切り換えて、硝化槽１８内の廃水のＳＳ成分濃度が５００ｍｇ／Ｌ未満になるまで、活性汚泥を余剰汚泥として系外に排出する。
【００４４】
また、硝化槽１８に浸漬する膜濾過器２６の膜の公称孔径が０．０１μｍを超えて０．１μｍ以下のものを使用する場合には、硝化槽１８内の廃水のＳＳ成分濃度が５００ｍｇ／Ｌ以上、３０００ｍｇ／Ｌ未満になるようにコントロールする。即ち、コントローラ３４は、ＳＳ濃度センサ３２によって測定される廃水のＳＳ成分濃度が３０００ｍｇ／Ｌを超えた場合には、汚泥ポンプ３６を運転すると共に、切換器４０を余剰汚泥管４２側に切り換えて、硝化槽１８内の廃水のＳＳ成分濃度が３０００ｍｇ／Ｌ未満になるまで、活性汚泥を余剰汚泥として系外に排出する。逆に、硝化槽１８内の廃水のＳＳ成分濃度が５００ｍｇ／Ｌを下回った場合には、コントローラ３４は、汚泥ポンプ３６を運転すると共に、切換器４０を汚泥返送管４４側に切り換え、且つ汚泥濃縮器４６を運転する。これにより、濃縮された汚泥が硝化槽１８に返送されるので、コントローラ３４は硝化槽１８内の廃水のＳＳ成分濃度が５００ｍｇ／Ｌ以上になるまで行う。
【００４５】
また、硝化槽１８に浸漬する膜濾過器２６の膜の公称孔径が０．１μｍを超えて０．８μｍ以下のものを使用する場合には、硝化槽１８内の廃水のＳＳ成分濃度が３０００ｍｇ／Ｌ以上になるようにコントロールする。即ち、コントローラ３４は、ＳＳ濃度センサ３２によって測定される硝化槽１８内の廃水のＳＳ成分濃度が３０００ｍｇ／Ｌを下回った場合には、汚泥ポンプ３６を運転すると共に、切換器４０を汚泥返送管４４側に切り換え、且つ汚泥濃縮器４６を運転する。これにより、濃縮された汚泥が硝化槽１８に返送されるので、コントローラ３４は硝化槽１８内の廃水のＳＳ成分濃度が３０００ｍｇ／Ｌ以上になるまで行う。尚、硝化槽１８内の被処理水のＳＳ成分濃度が３０００ｍｇ／Ｌ以上であればよいが、余りＳＳ成分濃度が大きくなりすぎると、膜の透過流束が低下する要因になるので、上限は２００００ｍｇ／Ｌ程度が好ましい。
【００４６】
かかるウイルスの除去において、添加物タンク４８から硝化槽１８内に、活性炭、ゼオライト、多孔性担体、凝集材の添加物のうちの少なくとも１つを添加することが好ましい。これにより、ＳＳ成分同士の吸着や凝集を促進すると共に、ＳＳ成分の主成分である活性汚泥の可溶化を防止できるので、ウイルスの膜濾過性能を更に向上させることができる。
【００４７】
このように第１の実施の形態によれば、膜の公称孔径を廃水から除去したいウイルスの大きさよりも大きく設定すると共に、膜濾過器２６に使用する膜の公称孔径に応じて廃水のＳＳ成分濃度をコントロールするようにしたので、膜の透過流束を低下させることなく廃水中のウイルスを完全に除去することができる。
【００４８】
尚、硝化槽１８内の廃水のＳＳ成分濃度が、上記した膜の各公称孔径との関係を満足している場合には、コントローラ３４は廃水のＳＳ成分濃度をコントロールする必要はない。
【００４９】
図２は、本発明のウイルス除去装置を、アンモニア性廃水（以下「廃水」という）の窒素除去を行う活性汚泥処理装置１０に適用した例であり、廃水のＳＳ成分濃度に応じて膜濾過器の膜の公称孔径をコントロール（管理）する第２の実施の形態である。尚、第１の実施の形態と同じ部材や装置には同符号を付して説明する。
【００５０】
活性汚泥処理装置１０において、原水配管１２を流れる廃水は、切換器４０によって３本の枝管１２（Ａ、Ｂ、Ｃ）に分岐されて第１〜第３の生物処理槽１４（Ａ、Ｂ、Ｃ）の何れかに供給される。第１〜第３の生物処理槽１４は脱窒槽１６（Ａ、Ｂ、Ｃ）と硝化槽１８（Ａ、Ｂ、Ｃ）とに区画され、第１の実施の形態と同様に硝化槽１８ではアンモニア性窒素の硝化処理が成され、脱窒槽１６では硝酸態窒素の脱窒処理が成される。
【００５１】
第１〜第３の生物処理槽１４の各硝化槽１８には、第１の実施の形態と同様に膜濾過器２６が浸漬されるが、第２の実施の形態では、各膜濾過器２６に使用される膜の公称孔径が異なるように設定される。即ち、第１硝化槽１８Ａには公称孔径が０．０１μｍ以下の膜が使用され、第２硝化槽１８Ｂには公称孔径が０．０１μｍを超えて０．１μｍ以下の範囲の膜が使用され、第３硝化槽１８Ｃには公称孔径が０．１μｍを超えて０．８μｍ以下の範囲の膜が使用される。また、原水配管１２には、流入廃水のＳＳ成分濃度を測定するＳＳ濃度センサ３２が設けられると共に、ＳＳ濃度センサ３２で測定された測定結果はコントローラ３４に入力される。そして、コントローラ３４は、ＳＳ濃度センサ３２の測定結果に基づいて、第１〜第３の生物処理槽１４の何れかに廃水が供給されるように切換器４０を切り換える。
【００５２】
上記の如く構成された第２の実施の形態の活性汚泥処理装置１０で廃水中に存在するウイルスを除去するウイルスの除去方法を説明する。
【００５３】
コントローラ３４は、ＳＳ濃度センサ３２で測定された廃水のＳＳ成分濃度が０ｍｇ／Ｌ以上、５００ｍｇ／Ｌ未満の場合には、第１の生物処理槽１４Ａに廃水が供給されるように切換器４０を切り換える。また、ＳＳ濃度センサ３２で測定された廃水のＳＳ成分濃度が５００ｍｇ／Ｌ以上、３０００ｍｇ／Ｌ未満の場合には、第２の生物処理槽１４Ｂに廃水が供給されるように切換器４０を切り換える。更に、ＳＳ濃度センサ３２で測定された廃水のＳＳ成分濃度が３０００ｍｇ／Ｌ以上の場合には、第３の生物処理槽１４Ｃに廃水が供給されるように切換器４０を切り換える。この場合、活性汚泥処理装置１０の運転当初は、硝化槽１８内のＳＳ成分濃度はＳＳ濃度センサ３２で測定された流入廃水のＳＳ成分濃度と同等にみることはできるが、運転経過時間と共に、膜濾過器２６で処理水と活性汚泥の分離が進むと、硝化槽１８内のＳＳ成分濃度が流入廃水のＳＳ成分濃度よりも大きくなる。従って、硝化槽１８底部に汚泥ポンプ３６を備えた汚泥排出管３８を設けると共に、硝化槽１８内に補助ＳＳ濃度センサ５４を設けて、補助ＳＳ濃度センサ５４での測定結果がコントローラ３４に入力されるようにすると良い。コントローラ３４は、補助ＳＳ濃度センサ５４で測定された硝化槽１８内の廃水のＳＳ成分濃度が、各硝化槽１８における上記した適正なＳＳ成分濃度の上限を超えたら、汚泥ポンプ３６を稼働して硝化槽１８内の活性汚泥を余剰汚泥として系外に排出する。
【００５４】
このように、第２の実施の形態によれば、硝化槽１８の廃水に浸漬した膜濾過器２６の膜の公称孔径を廃水から除去したいウイルスの大きさよりも大きく設定すると共に、廃水のＳＳ成分濃度に応じて膜濾過器２６に使用する膜の公称孔径をコントロール（管理）するようにしたので、膜の透過流束を低下させることなく水中のウイルスを完全に除去することができる。かかるウイルスの除去において、添加物タンク４８から硝化槽１８内に、活性炭、ゼオライト、多孔性担体、凝集材の添加物のうちの少なくとも１つを添加することが好ましい。
【００５５】
尚、上記した活性汚泥処理装置１０の第１、及び第２の実施の形態は、本発明のウイルス除去装置を組み込んだ構成の一例を示したものであり、この構成に限定されるものではない。例えば、第２の実施の形態では、流入廃水のＳＳ成分濃度に応じて廃水の流入先を第１〜第３の生物処理槽１４に切り換えるようにしたが、流入廃水のＳＳ成分濃度が一定の場合には、１つの生物処理槽にして硝化槽に設置する膜濾過器の膜の公称孔径を一定のＳＳ成分濃度に対応するように設定してもよい。
【００５６】
【発明の効果】
以上説明したように、本発明のウイルス除去方法及び装置によれば、膜の透過流束を低下させることなく水中のウイルスを完全に除去することができる。
【図面の簡単な説明】
【図１】本発明のウイルス除去装置を活性汚泥処理装置に組み込んだ第１の実施の形態を説明する構成図
【図２】本発明のウイルス除去装置を活性汚泥処理装置に組み込んだ第２の実施の形態を説明する構成図
【符号の説明】
１０…活性汚泥処理装置、１２…原水配管、１４…生物処理槽、１６…脱窒槽、１８…硝化槽、２０…循環配管、２２…ブロア、２４…曝気配管、２６…膜濾過器、２８…処理水配管、３０…吸引ポンプ、３２…ＳＳ濃度センサ、３４…コントローラ、３６…汚泥ポンプ、３８…汚泥排出管、４０…切換器、４２…余剰汚泥管、４４…汚泥返送管、４６…汚泥濃縮器、４８…添加物タンク[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a virus removal method and apparatus, and in particular, a virus removal method for removing viruses from water by filtering the viruses present in water such as sewers, lake water, river water, and pool water by membrane filtration. Relates to the device.
[0002]
[Prior art]
It has been found that many types of viruses exist in water such as sewers, lakes, rivers, and aquariums, but some types of viruses can harm people and livestock. It has become necessary to remove or inactivate viruses.
[0003]
Examples of conventional general methods for removing or inactivating viruses inhabiting water include a method of chlorinating water in which viruses are present, a method of ozone treatment, a method of irradiating ultraviolet rays, and a method of heating.
[0004]
In addition to these, Patent Document 1 includes a porous carrier having a diameter of 50 to 500 μm for inhabiting ciliates in a region where ciliates of the membrane mouth exist, and passes water in which the virus exists in this region. A method for removing a virus by incorporating it into a ciliate is disclosed. Furthermore, Patent Document 2 discloses a virus selective removal material using an organic material having an amine compound immobilized on the material surface as a membrane.
[0005]
However, chlorination is a problem of residual chlorine, ozone treatment and ultraviolet irradiation treatment are treatment costs, heat treatment cannot be applied to heat-resistant viruses, and is unsuitable for treatment of large quantities of water such as sewers. . In addition, Patent Document 1 has a disadvantage that it requires a ciliate of the membrane mouth and that it is difficult to completely remove the virus due to variations in virus uptake into the ciliate. Patent Document 2 is intended for use in the pharmaceutical industry and the like that selectively removes viruses from protein solutions containing plasma or blood components, and is not suitable for removing viruses from a large amount of water such as sewers. It is.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-137783
[Patent Document 2]
Japanese Patent Laid-Open No. 6-114250
[Problems to be solved by the invention]
By the way, a membrane filtration method has attracted attention as a method for removing viruses from sewage such as sewers. This membrane filtration method is suitable for removing viruses from sewage such as sewage, because there is no chemical residue, treatment cost problems, heat-resistant virus problems, etc., and water purification can be performed together.
[0009]
However, this membrane filtration method requires the use of a membrane with a pore size smaller than the size of the virus in order to completely remove the virus from the water. This reduces the permeation flux of the membrane. There is a drawback that the treatment efficiency is poor in treating the water.
[0010]
The present invention has been made in view of such problems, and an object of the present invention is to provide a virus removal method and apparatus that can completely remove viruses in water without reducing the permeation flux of the membrane.
[0011]
[Means for Solving the Problems]
The inventor of the present invention is that the virus present in water is easily adsorbed by the SS component, and the apparent diameter increases by being adsorbed by the SS component. Therefore, even if the membrane has a larger nominal pore size than the virus. The knowledge that the virus can be membrane filtered was obtained. Furthermore, by properly controlling the mutual relationship between the nominal pore size of the membrane larger than the virus and the SS component concentration in the treatment tank, the virus in the water can be completely removed without reducing the permeation flux of the membrane. I also got the knowledge. The present invention has been made based on such findings.
[0012]
Claim 1 of the present invention is a virus removal method for immersing a membrane filter in water to be treated in a treatment tank and removing viruses present in the water to be treated by membrane filtration in order to achieve the above object. A membrane having a nominal pore size larger than the size of the virus to be removed from the water to be treated is set, and the SS component concentration of the water to be treated is measured, and the nominal pore size of the membrane is approximately equal to the size of the virus . When using a membrane filter of 01 μm or less, the SS component concentration of the treated water is controlled so that the measured SS component concentration exceeds 0 mg / L and less than 500 mg / L, and the nominal pore size of the membrane When using a membrane filter having a thickness of more than 0.01 μm and not more than 0.1 μm, the measured SS component concentration is 500 mg / L or more and less than 3000 mg / L. When the SS component concentration of treated water is controlled and a membrane filter having a nominal pore size of more than 0.1 μm and not more than 0.8 μm is used, the measured SS component concentration should be 3000 mg / L or more. The SS component concentration of the water to be treated is controlled.
[0013]
According to claim 1 of the present invention, the nominal pore size of the membrane is set to be larger than the size of the virus to be removed from the treated water, and the SS component of the treated water according to the nominal pore size of the membrane used in the membrane filter Since the concentration is controlled, the virus in the water to be treated can be completely removed without lowering the permeation flux of the membrane.
[0014]
Claim 2 of the present invention is a virus removal method for immersing a membrane filter in water to be treated in a treatment tank to remove the virus present in the water to be treated by membrane filtration in order to achieve the above object. While setting to a membrane having a nominal pore size larger than the size of the virus to be removed from the water to be treated, the SS component concentration of the water to be treated was measured, and the measured SS component concentration exceeded 0 mg / L, and 500 mg / L When less than L, the nominal pore size of the membrane used in the membrane filter is controlled to 0.01 μm or less, which is substantially equal to the size of the virus, and the measured SS component concentration is 500 mg / L or more and less than 3000 mg / L In this case, the nominal pore diameter of the membrane used in the membrane filter is controlled to be more than 0.01 μm and not more than 0.1 μm, and the measured SS component concentration is 300 μm. When more than mg / L is a nominal pore size of the membrane used for the membrane filtration unit, beyond 0.1μm, characterized in that to control below 0.8 [mu] m.
[0015]
According to claim 2 of the present invention, the nominal pore size of the membrane is set larger than the size of the virus to be removed from the water to be treated, and the membrane filter is used according to the SS component concentration of the water to be treated. Since the nominal pore size of the membrane is controlled (controlled), the virus in the water to be treated can be completely removed without reducing the permeation flux of the membrane.
[0016]
Here, the SS component in the present invention means all solids floating in water, and when the present invention is applied to an activated sludge treatment apparatus, the main component of the SS component is activated sludge.
[0018]
This is because the SS component concentration of the water to be treated is controlled according to the nominal pore diameter of the membrane used in the membrane filter according to claim 1 or the SS component concentration of the water to be treated according to claim 2. When controlling the nominal pore size of the membrane used in the membrane filter, the relationship between the nominal pore size of the membrane and the SS component concentration is used to completely remove viruses in the water without reducing the permeation flux of the membrane. It is shown. In this case, when the nominal pore size of the membrane is 0.01 μm or less and the SS component concentration of the water to be treated exceeds 500 mg / L, the virus can be removed, but the permeation flux of the membrane decreases rapidly. Not good.
[0020]
This is because in claim 1, when a membrane filter having a nominal pore size of more than 0.01 μm and not more than 0.1 μm is used, the SS component concentration of water to be treated is 500 mg / L or more and 3000 mg / L. By controlling to less than, virus in water can be completely removed without lowering the permeation flux of the membrane. On the other hand, in claim 2, when the SS component concentration of the water to be treated is 500 mg / L or more and less than 3000 mg / L, the nominal pore diameter of the membrane used for the membrane filter exceeds 0.01 μm and is 0.1 μm or less. By controlling (controlling), it is possible to completely remove viruses in water without lowering the permeation flux of the membrane.
[0022]
In claim 1, when using a membrane filter having a nominal pore diameter of more than 0.1 μm and not more than 0.8 μm, the SS component concentration of the water to be treated should be controlled to 3000 mg / L or more. Thus, the virus in water can be completely removed without lowering the permeation flux of the membrane. If the SS component concentration is increased beyond 3000 mg / L, the film is likely to be clogged. From the viewpoint of clogging, the upper limit of the SS component concentration is preferably about 20000 mg / L. Further, in claim 2, when the SS component concentration of the water to be treated is 3000 mg / L or more, the nominal pore diameter of the membrane used for the membrane filter is controlled to more than 0.1 μm and 0.8 μm or less (management). By doing so, the virus in water can be completely removed without reducing the permeation flux of the membrane.
[0023]
A third aspect of the present invention is the first aspect of the present invention, wherein the treatment tank is an activated sludge treatment tank, and the amount of sludge drawn from the activated sludge treatment tank or the extracted sludge is concentrated and returned to the activated sludge treatment tank. The SS component concentration of the treated water is controlled by adjusting the sludge return amount.
This is because the virus removal method of the present invention is the most suitable method for the activated sludge treatment method generally used for sewage treatment of sewers, etc. It can be easily achieved by returning the concentrated sludge. That is, if the SS component concentration of the water to be treated is too low for the nominal pore size of the membrane of the membrane filter installed in the treatment tank, and the virus removal ability is reduced, the extracted sludge is concentrated by dehydration or the like. Return it to the treatment tank. Conversely, if the SS component concentration of the water to be treated is too high and the permeation flux of the membrane is lowered, the amount of sludge drawn is increased.
[0025]
A fourth aspect of the present invention is the method according to any one of the first to third aspects, wherein at least one of activated carbon, zeolite, a porous carrier, and an aggregating material additive is added to the treatment tank. .
[0026]
Thereby, while promoting adsorption and aggregation of SS components, solubilization of the activated sludge which is a main component of SS components can be prevented, so that the virus membrane filtration performance can be further improved.
[0029]
According to a fifth aspect of the present invention, in order to achieve the above object, in a virus removal apparatus for removing viruses present in the water to be treated by membrane filtration, a membrane having a nominal pore size larger than the size of the virus to be removed from the water to be treated A first treatment tank in which a membrane filter of 0.01 μm or less, which is substantially equal to the size of the virus, is immersed in the water to be treated; and a nominal pore diameter of the membrane is more than 0.01 μm and 0.1 μm or less A second treatment tank in which the membrane filter was immersed in the treated water, and a membrane filter having a nominal pore size of more than 0.1 μm and not more than 0.8 μm in the treated water. A treatment tank, a switching means for switching the inflow of the treated water to any of the first to third treatment tanks, a measuring means for measuring the SS component concentration of the inflowing treated water, and the measuring means Based on the measurement result of And a controller for controlling the changing means.
[0030]
Claim 5 of the present invention comprises the virus removal method of the present invention of Claim 2 as a specific apparatus.
[0031]
A sixth aspect of the present invention according to the fifth aspect is characterized in that, in the fifth aspect , an addition means for adding at least one of activated carbon, zeolite, porous carrier, and agglomerate additive into the treatment tank is provided.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a virus removal method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
[0033]
Before explaining the present invention, Table 1 explains the theoretical basis of the present invention.
[0034]
Table 1 shows the experimental results showing the relationship between the nominal pore size of the membrane of the membrane filter and the membrane filtration effect of the virus depending on the SS component concentration of the test water. When the concentration of the SS component was increased, it was investigated how many μm of the nominal pore diameter could remove the virus and maintain the permeation flux of the membrane. As the SS component, activated sludge was used assuming that the present invention was applied to an activated sludge treatment apparatus, and the activated sludge concentration (MLSS) in the test water was changed.
[0035]
[Table 1]

As a result, as can be seen from Table 1, in the range where MLSS exceeds 0 mg / L and less than 500 mg / L, by using a membrane of 0.01 μm or less whose virus size and nominal pore diameter are substantially equivalent, It could be removed completely and the permeation flux of the membrane could be maintained. When the MLSS is increased and the MLSS is in the range of 500 mg / L or more and less than 3000 mg / L, the virus is completely removed by using a membrane having a nominal pore size of 0.01 μm or more and less than 0.1 μm. And the permeation flux of the membrane could be maintained. When MLSS is further increased to 3000 mg / L or more, by using a membrane having a nominal pore size in the range of 0.1 μm or more and less than 0.8 μm, the virus can be completely removed and the permeation flux of the membrane is maintained. I was able to. Thus, by increasing the SS component concentration in the test water, the virus can be filtered with a membrane having a nominal pore size larger than the size of the virus. The reason is that the virus present in the test water is adsorbed by the SS component and It is considered that this is because the apparent diameter increases due to the adsorption. Moreover, in virus membrane filtration, it is preferable to add at least one of additives that promote adsorption and aggregation of SS components such as activated carbon, zeolite, porous carrier, and aggregating material to the water to be treated. This improves the adsorptivity of the SS component that has adsorbed the virus by the additive even if the SS component concentration is small, and thus the apparent size can be increased. In addition, when the SS component concentration is high, solubilization phenomenon of activated sludge, which is the main component of SS component, is likely to occur and viruses are easily redispersed, but solubilization of activated sludge is possible by adding the above-mentioned additives. The phenomenon can be suppressed.
[0036]
The present invention constitutes a virus removal method and apparatus based on such knowledge.
[0037]
FIG. 1 is an example in which the virus removal apparatus of the present invention is applied to an activated sludge treatment apparatus 10 that removes nitrogen from ammoniacal wastewater (hereinafter referred to as “wastewater”), and has a nominal pore diameter of a membrane used in a membrane filter. It is 1st Embodiment which controls SS component density | concentration of wastewater according to it.
[0038]
In the activated sludge treatment apparatus 10, wastewater flows from the raw water pipe 12 into the biological treatment tank 14. The biological treatment tank 14 is divided into a denitrification tank 16 and a nitrification tank 18, and the liquid in the nitrification tank 18 is circulated to the denitrification tank 16 via a circulation pipe 20. In the nitrification tank 18, air is aerated from the aeration pipe 24 connected to the blower 22, the wastewater and activated sludge come into contact under aerobic conditions, and ammonia nitrogen in the wastewater is nitrified to nitrate nitrogen. On the other hand, in the denitrification tank 16, nitrate nitrogen produced by nitrification in the nitrification tank 18 and circulated through the circulation pipe 20 is denitrified into nitrogen gas under anaerobic conditions.
[0039]
In addition, a membrane filter 26 is immersed in the wastewater in the nitrification tank 18, and the membrane filter 26 is connected to the treated water pipe 28, and a suction pump 30 is disposed in the treated water pipe 28. Thereby, the liquid in the nitrification tank 18 is suction filtered by the membrane of the membrane filter 26 and separated into treated water and activated sludge, and the treated water is discharged out of the system through the treated water pipe 28. Such membrane filtration also removes viruses present in the wastewater.
[0040]
In the present invention, the nominal pore size of the membrane used for the membrane filter 26 is set larger than the size of the virus to be removed. Furthermore, an SS concentration sensor 32 such as a turbidimeter is provided in the nitrification tank 18 to measure the SS component concentration of the wastewater in the nitrification tank 18, and the measurement result measured by the SS concentration sensor 32 is a controller. 34. A sludge discharge pipe 38 provided with a sludge pump 36 is extended from the bottom of the nitrification tank 18 and connected to a switching device 40, and the flow of discharged sludge is switched by the switching device 40 to an excess sludge pipe 42 and a sludge return pipe 44. And can be switched. In this case, the return destination of the sludge by the sludge return pipe 44 may be the nitrification tank 18 or the denitrification tank 16. Then, the controller 34 switches between the excess sludge pipe 42 and the sludge return pipe 44 by the switch 40 based on the measurement result measured by the SS concentration sensor 32. A sludge concentrator 46 such as a dehydrator is provided in the middle of the sludge return pipe 44 to concentrate the sludge concentration, and the degree of concentration is controlled by the controller 34.
[0041]
Further, an additive tank 48 is provided above the nitrification tank 18, and at least one of the additive of activated carbon, zeolite, porous carrier, and aggregating material is stored in the additive tank 48. An addition pipe 50 extends from the additive tank 48 to the nitrification tank 18, and an adjustment valve 52 that adjusts the amount of additive added is provided in the addition pipe 50.
[0042]
Next, a virus removal method for removing viruses present in wastewater with the activated sludge treatment apparatus 10 of the first embodiment configured as described above will be described.
[0043]
When the nominal pore size of the membrane used in the membrane filter 26 immersed in the nitrification tank 18 is 0.01 μm or less, the SS component concentration of the wastewater in the nitrification tank 18 exceeds 0 mg / L and less than 500 mg / L Control to maintain the range. That is, when the SS component concentration measured by the SS concentration sensor 32 exceeds 500 mg / L, the controller 34 operates the sludge pump 36 and switches the switcher 40 to the excess sludge pipe 42 side. The activated sludge is discharged out of the system as surplus sludge until the SS component concentration of the wastewater in the nitrification tank 18 becomes less than 500 mg / L.
[0044]
When the membrane filter 26 immersed in the nitrification tank 18 uses a membrane having a nominal pore diameter of more than 0.01 μm and 0.1 μm or less, the SS component concentration of the wastewater in the nitrification tank 18 is 500 mg / Control to be L or more and less than 3000 mg / L. That is, when the SS component concentration measured by the SS concentration sensor 32 exceeds 3000 mg / L, the controller 34 operates the sludge pump 36 and switches the switcher 40 to the surplus sludge pipe 42 side. The activated sludge is discharged out of the system as surplus sludge until the SS component concentration of the wastewater in the nitrification tank 18 becomes less than 3000 mg / L. On the other hand, when the SS component concentration of the wastewater in the nitrification tank 18 falls below 500 mg / L, the controller 34 operates the sludge pump 36 and switches the switcher 40 to the sludge return pipe 44 side. The concentrator 46 is operated. Thereby, since the concentrated sludge is returned to the nitrification tank 18, the controller 34 performs until the SS component density | concentration of the wastewater in the nitrification tank 18 becomes 500 mg / L or more.
[0045]
When the membrane filter 26 immersed in the nitrification tank 18 has a nominal pore diameter of more than 0.1 μm and 0.8 μm or less, the SS component concentration of wastewater in the nitrification tank 18 is 3000 mg / Control to be above L. That is, when the SS component concentration in the nitrification tank 18 measured by the SS concentration sensor 32 falls below 3000 mg / L, the controller 34 operates the sludge pump 36 and switches the switch 40 to the sludge return pipe. Switch to the 44 side and operate the sludge concentrator 46. Thereby, since the concentrated sludge is returned to the nitrification tank 18, the controller 34 performs until the SS component density | concentration of the wastewater in the nitrification tank 18 becomes 3000 mg / L or more. The SS component concentration of the water to be treated in the nitrification tank 18 may be 3000 mg / L or more. However, if the SS component concentration is excessively large, the permeation flux of the membrane decreases, so the upper limit is About 20000 mg / L is preferable.
[0046]
In the removal of the virus, it is preferable to add at least one of activated carbon, zeolite, porous carrier, and aggregating material additive from the additive tank 48 into the nitrification tank 18. Thereby, while promoting adsorption and aggregation of SS components, solubilization of the activated sludge which is a main component of SS components can be prevented, so that the virus membrane filtration performance can be further improved.
[0047]
As described above, according to the first embodiment, the nominal pore size of the membrane is set larger than the size of the virus to be removed from the wastewater, and the SS component of the wastewater is set according to the nominal pore size of the membrane used for the membrane filter 26. Since the concentration is controlled, the virus in the wastewater can be completely removed without lowering the permeation flux of the membrane.
[0048]
In addition, when the SS component concentration of the wastewater in the nitrification tank 18 satisfies the relationship with each nominal pore diameter of the membrane described above, the controller 34 does not need to control the SS component concentration of the wastewater.
[0049]
FIG. 2 is an example in which the virus removal apparatus of the present invention is applied to an activated sludge treatment apparatus 10 that removes nitrogen from ammoniacal wastewater (hereinafter referred to as “wastewater”), and a membrane filter according to the SS component concentration of the wastewater. This is a second embodiment for controlling (controlling) the nominal pore diameter of the membrane. The same members and devices as those in the first embodiment will be described with the same reference numerals.
[0050]
In the activated sludge treatment apparatus 10, the waste water flowing through the raw water pipe 12 is branched into three branch pipes 12 (A, B, C) by a switcher 40 to be first to third biological treatment tanks 14 (A, B). , C). The first to third biological treatment tanks 14 are divided into a denitrification tank 16 (A, B, C) and a nitrification tank 18 (A, B, C), and in the nitrification tank 18 as in the first embodiment. Nitrification treatment of ammonia nitrogen is performed, and denitrification treatment of nitrate nitrogen is performed in the denitrification tank 16.
[0051]
The membrane filter 26 is immersed in each nitrification tank 18 of the first to third biological treatment tanks 14 as in the first embodiment, but in the second embodiment, each membrane filter 26 is immersed. The nominal pore size of the membrane used in the above is set to be different. That is, a membrane having a nominal pore diameter of 0.01 μm or less is used for the first nitrification tank 18A, and a membrane having a nominal pore diameter of more than 0.01 μm and 0.1 μm or less is used for the second nitrification tank 18B. A film having a nominal pore diameter exceeding 0.1 μm and 0.8 μm or less is used for the third nitrification tank 18C. The raw water pipe 12 is provided with an SS concentration sensor 32 for measuring the SS component concentration of the inflow wastewater, and the measurement result measured by the SS concentration sensor 32 is input to the controller 34. Based on the measurement result of the SS concentration sensor 32, the controller 34 switches the switcher 40 so that wastewater is supplied to any one of the first to third biological treatment tanks 14.
[0052]
A virus removal method for removing viruses present in wastewater with the activated sludge treatment apparatus 10 of the second embodiment configured as described above will be described.
[0053]
When the SS component concentration measured by the SS concentration sensor 32 is 0 mg / L or more and less than 500 mg / L, the controller 34 switches the switch 40 so that the waste water is supplied to the first biological treatment tank 14A. Switch. When the SS component concentration measured by the SS concentration sensor 32 is 500 mg / L or more and less than 3000 mg / L, the switch 40 is switched so that the waste water is supplied to the second biological treatment tank 14B. . Furthermore, when the SS component concentration of the wastewater measured by the SS concentration sensor 32 is 3000 mg / L or more, the switcher 40 is switched so that the wastewater is supplied to the third biological treatment tank 14C. In this case, at the beginning of the operation of the activated sludge treatment apparatus 10, the SS component concentration in the nitrification tank 18 can be seen to be equivalent to the SS component concentration of the influent wastewater measured by the SS concentration sensor 32. When separation of treated water and activated sludge proceeds in the membrane filter 26, the SS component concentration in the nitrification tank 18 becomes higher than the SS component concentration of the inflow wastewater. Accordingly, a sludge discharge pipe 38 having a sludge pump 36 is provided at the bottom of the nitrification tank 18, and an auxiliary SS concentration sensor 54 is provided in the nitrification tank 18, and the measurement result of the auxiliary SS concentration sensor 54 is input to the controller 34. It is good to do so. The controller 34 operates the sludge pump 36 when the SS component concentration of the wastewater in the nitrification tank 18 measured by the auxiliary SS concentration sensor 54 exceeds the upper limit of the appropriate SS component concentration in each nitrification tank 18. The activated sludge in the nitrification tank 18 is discharged out of the system as surplus sludge.
[0054]
Thus, according to the second embodiment, the nominal pore diameter of the membrane of the membrane filter 26 immersed in the wastewater of the nitrification tank 18 is set larger than the size of the virus that is desired to be removed from the wastewater, and the SS component of the wastewater Since the nominal pore size of the membrane used in the membrane filter 26 is controlled according to the concentration, viruses in water can be completely removed without lowering the permeation flux of the membrane. In the removal of the virus, it is preferable to add at least one of activated carbon, zeolite, porous carrier, and aggregating material additive from the additive tank 48 into the nitrification tank 18.
[0055]
In addition, 1st and 2nd embodiment of the above-mentioned activated sludge processing apparatus 10 showed an example of the structure incorporating the virus removal apparatus of this invention, and is not limited to this structure. . For example, in the second embodiment, the wastewater inflow destination is switched to the first to third biological treatment tanks 14 in accordance with the SS component concentration of the inflow wastewater, but the SS component concentration of the inflow wastewater is constant. In this case, the nominal pore diameter of the membrane filter membrane installed in the nitrification tank as a single biological treatment tank may be set to correspond to a constant SS component concentration.
[0056]
【The invention's effect】
As described above, according to the virus removal method and apparatus of the present invention, viruses in water can be completely removed without reducing the permeation flux of the membrane.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a first embodiment in which a virus removal apparatus of the present invention is incorporated in an activated sludge treatment apparatus. FIG. 2 is a second view in which a virus removal apparatus of the present invention is incorporated in an activated sludge treatment apparatus. Configuration diagram for explaining an embodiment [Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Activated sludge processing apparatus, 12 ... Raw water piping, 14 ... Biological treatment tank, 16 ... Denitrification tank, 18 ... Nitrification tank, 20 ... Circulation piping, 22 ... Blower, 24 ... Aeration piping, 26 ... Membrane filter, 28 ... Treated water piping, 30 ... suction pump, 32 ... SS concentration sensor, 34 ... controller, 36 ... sludge pump, 38 ... sludge discharge pipe, 40 ... switch, 42 ... surplus sludge pipe, 44 ... sludge return pipe, 46 ... sludge Concentrator, 48 ... Additive tank

Claims

In the virus removal method of immersing a membrane filter in the treated water in the treatment tank and removing the virus present in the treated water by membrane filtration,
While setting to a membrane having a larger nominal pore size than the size of the virus to be removed from the treated water, measuring the SS component concentration of the treated water,
When a membrane filter having a nominal pore size of the membrane of 0.01 μm or less, which is substantially the same as the size of the virus, is used, the measured SS component concentration is more than 0 mg / L and less than 500 mg / L. Control the SS component concentration of the treated water,
When using a membrane filter having a nominal pore size of more than 0.01 μm and not more than 0.1 μm, the treated water is adjusted so that the measured SS component concentration is 500 mg / L or more and less than 3000 mg / L. Control SS component concentration,
When using a membrane filter having a nominal pore diameter of more than 0.1 μm and less than 0.8 μm, the SS component concentration of the water to be treated is controlled so that the measured SS component concentration is 3000 mg / L or more. A virus removal method comprising:

In the virus removal method of immersing a membrane filter in the treated water in the treatment tank and removing the virus present in the treated water by membrane filtration,
While setting to a membrane having a larger nominal pore size than the size of the virus to be removed from the treated water, measuring the SS component concentration of the treated water,
When the measured SS component concentration exceeds 0 mg / L and less than 500 mg / L, the nominal pore size of the membrane used for the membrane filter is controlled to 0.01 μm or less, which is substantially equal to the size of the virus ,
When the measured SS component concentration is 500 mg / L or more and less than 3000 mg / L, the nominal pore size of the membrane used for the membrane filter is controlled to be more than 0.01 μm and not more than 0.1 μm,
When the measured SS component concentration is 3000 mg / L or more, the nominal pore size of the membrane used for the membrane filter is controlled to be more than 0.1 μm and 0.8 μm or less.

The treatment tank is an activated sludge treatment tank, and the amount to be treated is adjusted by adjusting the amount of sludge drawn from the activated sludge treatment tank or the amount of sludge returned to concentrate the concentrated sludge and return it to the activated sludge treatment tank. 2. The virus removal method according to claim 1, wherein the SS component concentration of water is controlled.

The virus removal method according to any one of claims 1 to 3, wherein at least one of activated carbon, zeolite, a porous carrier, and an aggregating material additive is added to the treatment tank.

In a virus removal apparatus that removes viruses present in the water to be treated by membrane filtration,
A first treatment tank in which a membrane filter having a nominal pore size larger than the size of the virus to be removed from the water to be treated and having a diameter of 0.01 μm or less, which is substantially equal to the size of the virus, is immersed in the water to be treated. When,
A second treatment tank in which a membrane filter having a nominal pore size of more than 0.01 μm and not more than 0.1 μm is immersed in the water to be treated;
A third treatment tank in which a membrane filter having a nominal pore diameter of more than 0.1 μm and not more than 0.8 μm is immersed in the water to be treated;
Switching means for switching inflow of the water to be treated to any of the first to third treatment tanks;
Measuring means for measuring the SS component concentration of the treated water flowing in;
And a controller for controlling the switching means based on a measurement result of the measuring means.

6. The virus removing apparatus according to claim 5, further comprising addition means for adding at least one of activated carbon, zeolite, porous carrier, and aggregating material additive to the treatment tank.