JP2004154697A

JP2004154697A - Colored waste water treatment method and apparatus used for it

Info

Publication number: JP2004154697A
Application number: JP2002323427A
Authority: JP
Inventors: Masaru Funaki; 大舟木
Original assignee: Seiwa Kogyo KK
Current assignee: Seiwa Kogyo KK
Priority date: 2002-11-07
Filing date: 2002-11-07
Publication date: 2004-06-03
Anticipated expiration: 2022-11-07
Also published as: JP3848238B2

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently perform decolonization of colored waste water and reduction of COD and BOD without discharging a large amount of residue and surplus sludge. <P>SOLUTION: A colored waste water treatment method comprises a hydrogen peroxide treatment process A for treating the colored waste water with hydrogen peroxide to reduce COD to 90% or lower, and an ozone treatment process B for treating the treated water, which has been subjected to the hydrogen peroxide treatment, with ozone. In this treatment method, after the ozone treatment process B, one or more cycles of the hydrogen peroxide treatment and the ozone treatment may be additionally applied to the treated water in this order. The ozone treatment process B may comprise a process B1 for supplying the treated water which has been subjected to the hydrogen peroxide treatment into a vortex pump by pressurizing the treated water by a liquid feed pump and introducing ozone-containing gas thereinto at the same time to agitate and mix them in the vortex pump. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は染色廃水などの着色廃水の処理方法とそれに用いる着色廃水処理装置に関する。
【０００２】
【従来の技術】
従来、染色廃水などの着色廃水中に含まれる溶解性有機物や色素を除去する方法として、金属イオン及び高分子系凝集剤を用いて色素の除去を行う脱色工程と、活性汚泥処理法等の生物酸化法により溶解性有機物を分解する生物酸化処理工程とを組み合わせた方法が知られている。しかし、この方法では、脱色工程において多量の薬品を使用する上、脱色工程に伴う凝集沈殿処理や加圧浮上処理等で大量の残渣が発生すると共に、生物酸化処理工程において余剰汚泥が発生し、これらの残渣や余剰汚泥の処理が大きな問題となる。
【０００３】
これに対して、着色廃水をオゾンで処理して脱色する方法も知られている。しかし、着色廃水をオゾンのみで処理すると、廃水の着色度は低下するものの、ＣＯＤ値は十分に低減されず、ＢＯＤ値については増加する場合もある。そのため、オゾン処理後に微生物処理を施すことが必要であり（例えば、特許文献１及び２参照）、上記と同様、余剰汚泥の処理が問題となる。なお、難分解性廃水の処理法として、通常のオゾン処理の際に少量の過酸化水素を添加して処理を行う促進酸化法が知られているが、この方法では脱色とＣＯＤ及びＢＯＤの低減が不十分である。
【０００４】
【特許文献１】
特開昭４９−９８０５５号公報
【特許文献２】
特開平６−２５４５７５号公報
【０００５】
【発明が解決しようとする課題】
従って、本発明の目的は、着色廃水の脱色とＣＯＤ（化学的酸素要求量）及びＢＯＤ（生物化学的酸素要求量）の低減を、多量の残渣や余剰汚泥を排出させることなく効率よく行うことのできる着色廃水の処理方法とそれに用いる装置を提供することにある。
本発明の他の目的は、着色廃水に対してオゾンによる酸化処理を効率よく施すことのできる着色廃水の処理方法とそれに用いる装置を提供することにある。
【０００６】
【課題を解決するための手段】
本発明者らは、前記目的を達成するため鋭意検討した結果、着色廃水に対し、まず過酸化水素処理を施してＣＯＤを９０％以下に低減した後にオゾン処理を施すと、脱色だけでなく、ＣＯＤ及びＢＯＤの低減を効率よく行うことができることを見出した。また、オゾン処理工程において、渦流ポンプ内に被処理液を送液ポンプにより圧力を加えて供給すると共にオゾン含有ガスを導入し、該渦流ポンプ内で両者を攪拌混合したり、被処理液とオゾン含有ガスとの気液混合物を、液深（高さ）と槽の内径の比及び槽内の液面と槽底間の圧力損失が特定の範囲となる気液分離反応槽に供給してオゾン酸化と共に気液分離を行うと、オゾンによる酸化処理を極めて効率よく行えることを見出した。本発明はこれらの知見に基づいて完成されたものである。
【０００７】
すなわち、本発明は、着色廃水に過酸化水素処理を施してＣＯＤを９０％以下に低減する過酸化水素処理工程Ａと、過酸化水素処理を施した処理液にオゾン処理を施すオゾン処理工程Ｂとを含む着色廃水の処理方法を提供する。
【０００８】
この処理方法において、前記オゾン処理工程Ｂの後、この処理液に対してさらに過酸化水素処理とオゾン処理とをこの順序で１サイクル以上施してもよい。前記過酸化水素処理は酸素曝気下で行うのが好ましい。
【０００９】
前記オゾン処理工程Ｂは、渦流ポンプ内に、過酸化水素処理を施した処理液を送液ポンプにより圧力を加えて供給すると共にオゾン含有ガスを導入し、該渦流ポンプ内で両者を攪拌混合する工程Ｂ１を含んでいてもよく、またこれに加えて、工程Ｂ１で得られた気液混合物を管路内ミキサーで攪拌混合する工程Ｂ２や、さらに、工程Ｂ２で得られた気液混合物を気液分離反応槽内でオゾン酸化と共に気液分離する工程Ｂ３を含んでいてもよい。前記渦流ポンプ内へのオゾン含有ガスと過酸化水素処理液との供給比（前者／後者；容量比）は、例えば２０／８０以上である。また、前記気液分離反応槽における液深（高さ）Ｌと槽の内径Ｄとの比（Ｌ／Ｄ）は、例えば１．０〜１０であり、気液分離反応槽内の液面と槽底間の圧力損失は例えば０．０５ＭＰａ以上である。
【００１０】
本発明は、また、着色廃水にオゾン処理を施す着色廃水の処理方法であって、渦流ポンプ内に、被処理液を送液ポンプにより圧力を加えて供給すると共にオゾン含有ガスを導入し、該渦流ポンプ内で両者を攪拌混合する工程を含む着色廃水の処理方法を提供する。この処理方法は、渦流ポンプ内で攪拌混合して得られた気液混合物をさらに管路内ミキサーで攪拌混合する工程を含んでいてもよい。
【００１１】
本発明は、さらに、着色廃水にオゾン処理を施す着色廃水の処理方法であって、オゾン含有ガスと被処理液との気液混合物を、液深（高さ）Ｌと槽の内径Ｄとの比（Ｌ／Ｄ）が１．０〜１０であり且つ液面と槽底間の圧力損失が０．０５ＭＰａ以上となる気液分離反応槽内に供給し、オゾン酸化と共に気液分離を行う工程を含む着色廃水の処理方法を提供する。
【００１２】
本発明は、さらにまた、着色廃水を処理するための装置であって、被処理液とオゾン含有ガスとを攪拌混合するための渦流ポンプと、前記被処理液を渦流ポンプ内に圧力を加えて供給するための送液ポンプとを備えた着色廃水処理装置を提供する。
【００１３】
本発明は、また、着色廃水を処理するための装置であって、オゾン含有ガスと被処理液との気液混合物を供給するための供給口を有し、液深（高さ）Ｌと槽の内径Ｄとの比（Ｌ／Ｄ）が１．０〜１０であり且つ液面と槽底間の圧力損失が０．０５ＭＰａ以上となる気液分離反応槽を備えた着色廃水処理装置を提供する。
【００１４】
本発明は、さらにまた、着色廃水を処理するための装置であって、着色廃水に過酸化水素処理を施す過酸化水素処理装置と、過酸化水素処理を施した過酸化水素処理液とオゾン含有ガスとを攪拌混合するための渦流ポンプと、前記過酸化水素処理液を渦流ポンプ内に圧力を加えて供給するための送液ポンプと、渦流ポンプ内で攪拌混合して得られた気液混合物をさらに攪拌混合する管路内ミキサーと、管路内ミキサーで攪拌混合して得られた気液混合物をオゾン酸化と共に気液分離するための気液分離反応槽であって、液深（高さ）Ｌと槽の内径Ｄとの比（Ｌ／Ｄ）が１．０〜１０であり且つ液面と槽底間の圧力損失が０．０５ＭＰａ以上となる気液分離反応槽とを備えた着色廃水処理装置を提供する。
【００１５】
【発明の実施の形態】
以下、本発明を、図面を参照しつつ詳細に説明する。図１は、本発明の着色廃水の処理方法の１例を示す概略工程図である。この例では、着色廃水１は原水ピット２からポンプ３によりフィルタ４及び熱交換器５を通って曝気槽１０に導入される。フィルタ４は着色廃水１中のＳＳ（残渣）を取り除くため、また熱交換器５は着色廃水１を冷却するために設けられている。曝気槽１０の手前で、着色廃水１に放流水６（必要に応じて）とポンプ８により過酸化水素水７が添加され、それらの混合液が曝気槽１０内へ入る。曝気槽１０では、空気がブロワ９にて送られ散気板１１により曝気しており、ここで過酸化水素処理が施される。曝気槽１０は２槽に分かれており、上澄み液が２槽目に入る。なお、原水ピット２内の着色廃水を「濃厚廃水」、濃厚廃水に放流水６を加えたものを「希釈原水」と称することがある。
【００１６】
着色廃水１としては着色成分を含有する広範な廃水を使用できる。その代表的な例として、例えば、染色工場における染色工程等からの着色廃水（染色廃水）、染料工場からの着色廃水、パルプ工場におけるパルプ製造時に排出される着色廃水、化学工場や食品工場からの着色廃水、養豚場からの着色廃水、鉄鋼プラントからの着色廃水などが挙げられる。
【００１７】
過酸化水素処理により、主として着色廃水中に含まれるＣＯＤ要素が除去され、被処理液のＣＯＤが低減される。ＣＯＤはこの過酸化水素処理によって９０％以下にまで低減するのが好ましい。オゾン処理工程の前に過酸化水素処理工程を設けることにより、オゾン処理工程におけるオゾンの使用量を著しく低減できるだけでなく、着色廃水に直接オゾン処理を施す場合と比較して、オゾン処理によるＣＯＤ及びＢＯＤの低減効率が大幅に向上する。これは、過酸化水素によって、着色廃水中の有機物質がオゾンに対してより酸化されやすい物質に変換されるためであると推測される。着色廃水の種類によっては過酸化水素処理によりＢＯＤが上昇することがあるが、続いて行うオゾン処理によりこのＢＯＤは極めて低い値となる。
【００１８】
過酸化水素（Ｈ_２Ｏ_２）の使用量としては、被処理液（着色廃水）に対して、例えば１０〜１０００重量ｐｐｍ、好ましくは２０〜５００重量ｐｐｍ、さらに好ましくは４０〜３００重量ｐｐｍ程度である。処理温度は、例えば０〜３０℃程度であり、常温で好適に処理を行うことができる。処理時間は、例えば１〜８時間、好ましくは２〜４時間程度である。過酸化水素処理は酸素曝気下で行うのが好ましい。酸素曝気下で過酸化水素処理を行うことにより酸化効率が大きく向上する。酸素としては、純粋な酸素、酸素と不活性ガスとの混合ガス、空気等の何れも用いてもよい。曝気量は、酸素として、被処理液１Ｌ当たり、例えば０．００８〜１．７Ｌ／分、好ましくは０．２〜０．８Ｌ／分程度である。
【００１９】
過酸化水素処理を施された着色廃水は、曝気槽１０の２槽目からポンプ１２によりフィルタ１３を通って原水タンク１４に入り、次いで、原水タンク１４から送液ポンプ１５により圧力を加えられることで、渦流ポンプ（混合ポンプ）１７及び管路内ミキサー１８を経て気液分離反応槽１９に供給される。このとき、渦流ポンプ１７内にオゾン発生装置１６で製造されたオゾン含有ガスが導入される。渦流ポンプ１７内に導入されたオゾンは被処理液（着色廃水）と攪拌混合されて小さな気泡となり、次いで管路内ミキサー１８によりさらに細かく裁断される。
【００２０】
送液ポンプ１５としては、送液可能なポンプであれば特に限定されないが、渦流ポンプなどが好ましい。渦流ポンプ１７としては、液体と気体とを導入可能で、羽根車の回転によって液に圧力と速度の両エネルギーを与え、導入された液体と気体を混合攪拌でき、且つ得られた気液混合物を吐出可能な構造を有するポンプであれば特に限定されず、市販の渦流タービンポンプなどを使用できる。
【００２１】
オゾン発生装置１６としては、特に限定されず、公知の装置を使用できる。オゾンを発生される際に用いる原料としては、空気のほか、空気から抽出した酸素、水の電気分解により得られる酸素などの何れであってもよい。高純度の酸素（例えば、９８％酸素）を用いることもできる。管路内ミキサー１８としては、管路内に配設されたミキサーであればよく、スタティックミキサー、ラインミキサーなどを使用できる。なかでもスタティックミキサーが好ましい。管路内ミキサー１８としては、気泡径を１０００μｍ以下にすることのできるものが好ましい。
【００２２】
上記のように、渦流ポンプ１７の吸込側に送液ポンプ１５を設けて圧力を加えて送液する方法によれば、被処理液が送液ポンプ１５の圧力により渦流ポンプ１７内に強制的に供給されるので、オゾン含有ガスと被処理液との供給比（前者／後者；容量比）が高くても、被処理液とオゾン含有ガスとの気液混合物が円滑に管路内ミキサー１８にまで送られ、そこで、気液が激しく攪拌混合される。そのため、オゾンと被処理液との接触効率が大きく向上し、オゾンの溶解効率も格段に上がり、ひいては気液分離反応槽におけるオゾンによる酸化効率が大幅に改善されることになる。また、送液ポンプ１５により被処理液に圧力が加えられていることから、オゾンの溶解量も増大する。なお、渦流ポンプの前に送液ポンプを設けない場合には、オゾン含有ガスと被処理液との供給比（前者／後者；容量比）が通常１０／９０を超えると、渦流ポンプが気泡を噛み、送液が円滑に行われなくなる。
【００２３】
渦流ポンプ１７へのオゾン含有ガスと被処理液（着色廃水）との供給比（前者／後者；容量比）は、例えば２０／８０以上であり、好ましくは３０／７０以上（例えば３０／７０〜７０／３０程度）、さらに好ましくは４０／６０以上（例えば４０／６０〜７０／３０程度）である。本発明では、オゾン発生の際に用いる原料酸素濃度を選択することにより、被処理液１Ｌに対して、２００ｍｇを超える量（例えば２１０〜５００ｍｇ、好ましくは２２０〜５００ｍｇ）のオゾンを供給することが可能である。
【００２４】
送液ポンプ１５の吐出側（渦流ポンプ１７の吸込側）の圧力（ゲージ圧）は、好ましくは０．０１〜０．１５ＭＰａ、さらに好ましくは０．０５〜０．１ＭＰａ程度であり、渦流ポンプ１７の吐出側（管路内ミキサーの入口側）の圧力（ゲージ圧）は、好ましくは０．０１〜０．１５ＭＰａ、さらに好ましくは０．０５〜０．１ＭＰａ程度であり、また管路内ミキサー１８の出口側（気液分離反応槽１９，２０の入口側）の圧力（ゲージ圧）は、好ましくは０．０１〜０．１ＭＰａ、さらに好ましくは０．０１〜０．０５ＭＰａ程度である。なお、オゾンは０．３ＭＰａ以上（全圧）の圧力（絶対圧）で自己分解するので、該圧力よりも低い圧力で気液混合操作を行う必要がある。
【００２５】
上記の方法によれば、被処理液とオゾン含有ガスとが効率よく攪拌混合されるため、気泡の大きさは極めて小さく、例えば平均気泡径を６００μｍ未満（一般に３００〜５００μｍ程度）とすることができる。
【００２６】
気液分離反応槽１９では、被処理液中の有機物等がオゾンにより酸化されるとともに、気液混合物が気体と液体とに分離される。このオゾン処理により、被処理液の色度が著しく低下し、且つＣＯＤ及びＢＯＤが大幅に低減する。気液分離反応槽は上記のほか、２基を並列に接続したり、３基以上を並列に接続して用いてもよい。
【００２７】
気液分離反応槽１９には、気液混合物の供給口及び分離した気体と液体を排出するための排出口が設けられている。気液分離反応槽１９としては、運転を実施しているとき、液深（高さ）Ｌと槽の内径Ｄとの比（Ｌ／Ｄ）が１．０〜１０（好ましくは１．０〜２．５、さらに好ましくは１．５〜２）であり、液面と槽底間の圧力損失が０．０５ＭＰａ以上（例えば０．０５〜０．２ＭＰａ、好ましくは０．１〜０．２ＭＰａ）となるものが好ましい。このような気液分離反応槽を用いると、反応槽の高さが低くても気液分離及び酸化反応が効率よく進行する。
【００２８】
液面と槽底間の圧力損失を０．１ＭＰａ以上にするための方法としては、例えば、反応槽内にメッシュ、多孔板、分散板などを１又は２以上（例えば２〜５枚程度）水平に配設して流路圧損を生じさせる方法などがある。メッシュや多孔板等を挿入することによりピストンフロー性が向上して、オゾン酸化効率も著しく増大する。前記圧損は、メッシュや多孔板の孔径や孔数、枚数などを適宜調整することによりコントロールできる。なお、前記気液混合物は気液分離反応槽の上部及び下部の何れより導入してもよいが、効率を高める点からは下部より導入するのが好ましい。気液分離反応槽は多段方式とすることもできる。
【００２９】
気液分離反応槽１９で分離された気体は排オゾン処理機３１で処理された後、排気される。排オゾン処理機３１としては、活性炭等の触媒や熱によるオゾン分解装置等、通常のオゾン処理装置を使用できる。
【００３０】
気液分離反応槽１９で分離された液は、渦流ポンプ（混合ポンプ）２０に導かれ、ここで再度オゾンと攪拌混合され、さらに管路内ミキサー２１で攪拌混合された後、気液分離反応槽２２に導入される。渦流ポンプ、管路内ミキサー、気液分離反応槽としては前記と同様のものを使用できる。このように、渦流ポンプでの気液の混合、管路内ミキサーによる攪拌、及び気液分離反応槽での反応と気液分離の一連の操作を２回以上繰り返すことにより、脱色及びＣＯＤとＢＯＤの低減をより確実に行うことができる。特に、オゾン処理後に再度過酸化水素処理を行うと、オゾンによって、着色廃水中の有機物質が過酸化水素に対してより分解されやすい物質に変換されるためか、次の過酸化水素処理でＢＯＤが著しく低減する。
【００３１】
気液分離反応槽２２で分離された気体は排オゾン処理機３１に送られて処理される。気液分離反応槽２２で分離された液は、途中で過酸化水素分解酵素２３がポンプ２４によって加えられ、さらに必要に応じて放流水３０が加えられ、排水ピット２７に流入する。排水ピット２７では、ｐＨ調整液２５（例えば、硫酸などの酸等）がポンプ２６により添加されてｐＨ調整がなされる。図中２８は攪拌機、２９はｐＨメーターである。排水ピット２７の内部は２つに区切られており、上澄み液が２槽目に入り、そこから河川に放流される。なお、気液分離反応槽で分離された液に過酸化水素分解酵素を加えたものを単に「処理水」と称することがある。また、この処理水に放流水を加えたものを単に「希釈処理水」と称することがある。
【００３２】
気液分離反応槽２２で分離された液に対して、再度、前記と同様の過酸化水素処理とオゾン処理とをこの順序で１回以上繰り返すと、脱色効果とＣＯＤ及びＢＯＤの低減効果は飛躍的に増大する。なお、２回目以降の過酸化水素処理においては、必ずしもＣＯＤを９０％以下に低減させなくてもよい。
【００３３】
【発明の効果】
本発明の着色廃水の処理方法によれば、多量の残渣や余剰汚泥を排出させることなく、広範な着色廃水に対して脱色とＣＯＤ及びＢＯＤの低減を行うことができる。また、着色廃水に過酸化水素処理を施してＣＯＤをある程度（例えば９０％以下にまで）低減した後にオゾン処理に付すので、オゾン処理工程におけるオゾンの使用量を減らすことができるだけでなく、脱色とＣＯＤ及びＢＯＤの低減効率も向上する。オゾン処理工程の後、この処理液に対してさらに過酸化水素処理とオゾン処理とをこの順序で１サイクル以上施す場合には、脱色とＣＯＤ及びＢＯＤの低減効率が飛躍的に向上する。過酸化水素処理を酸素曝気下で行う場合には、過酸化水素の酸化力が増大し、ＣＯＤ等の低減効率がより向上する。
【００３４】
着色廃水とオゾン含有ガスとの混合を渦流ポンプ内で行う際、着色廃水を送液ポンプを用いて圧力を加えて渦流ポンプ内に導入する場合には、渦流ポンプ内の気液混合物が強制的に押し出されるので、気泡を噛みにくくなり、気液比を大幅に増大できる。その結果、例えば、管路内ミキサーや気液分離反応槽における気液接触効率、オゾンの溶解効率が高まり、オゾンによる酸化反応効率（脱色及びＣＯＤ・ＢＯＤ低減効率）も大きく向上する。
【００３５】
着色廃水のオゾン処理を、液深（高さ）Ｌと槽の内径Ｄとの比（Ｌ／Ｄ）が１．０〜１０であり且つ槽内の液面と槽底間の圧力損失が０．０５ＭＰａ以上となるような気液分離反応槽を用いて行う場合には、該反応槽の高さが低くてもオゾン酸化効率を高くでき、しかも気液分離が効率よく進行する。
【００３６】
本発明の着色廃水処理装置は上記本発明の着色廃水の処理方法に好適に用いられる。
【００３７】
【実施例】
以下、実施例に基づいて本発明をより詳細に説明するが、本発明はこれらの実施例により何ら限定されるものではない。なお、透視度はＪＩＳＫ０１０２−９の方法、色度はＪＩＳＫ０１０１−１０．１の方法、ＳＳはＪＩＳＫ０１０２−１４．１の方法、ＣＯＤはＪＩＳＫ０１０２−１７の方法、ＢＯＤはＪＩＳＫ０１０２−２１，３２．３の方法に従って測定した。
【００３８】
実施例１
図１に示すフローに沿って染色廃水を処理した。なお、この例では過酸化水素処理工程についてのみ記す。
染色廃水１（濃厚廃水）に放流水６を加えて得られた希釈原水（透視度１ｃｍ、色度７５０、ｐＨ１０．２、ＳＳ９ｍｇ／Ｌ、ＣＯＤ３８０ｍｇ／Ｌ、ＢＯＤ２４０ｍｇ／Ｌ）５８Ｌと、３５重量％過酸化水素水６０ｍｌを曝気槽１０に入れ、空気を２０ｌ／分の流量で供給し、３．５時間曝気した。その結果、透視度１ｃｍ、色度８３０、ｐＨ９．７、ＳＳ１６ｍｇ／Ｌ、ＣＯＤ３０４ｍｇ／Ｌ、ＢＯＤ３３８ｍｇ／Ｌの液が得られた。ＣＯＤは８０％に低減された。
【００３９】
実施例２
希釈原水として、透視度１ｃｍ、色度８７０、ｐＨ１０．２、ＳＳ２０ｍｇ／Ｌ、ＣＯＤ３８０ｍｇ／Ｌ、ＢＯＤ２２０ｍｇ／Ｌのものを用いた点、３５重量％過酸化水素水を３０ｍｌ用いた点以外は実施例１と同様の操作を行った。その結果、透視度１ｃｍ、色度９３０、ｐＨ９．８、ＳＳ２９ｍｇ／Ｌ、ＣＯＤ３３４ｍｇ／Ｌ、ＢＯＤ４２８ｍｇ／Ｌの液が得られた。ＣＯＤは８７．９％に低減された。
【００４０】
実施例３
図１に示すフローに沿って染色廃水を処理した。なお、過酸化水素処理液を原水タンク１４に移すまではバッチ式で、それ以後は連続式で運転した。
染色廃水１（濃厚廃水）（透視度１ｃｍ、色度３３０、ｐＨ１０．１、ＳＳ１１ｍｇ／Ｌ、ＣＯＤ３０１ｍｇ／Ｌ、ＢＯＤ３０９ｍｇ／Ｌ）１．３ｔに放流水６（透視度１５ｃｍ、色度５０、ｐＨ６．６、ＳＳ３０ｍｇ／Ｌ、ＣＯＤ４５ｍｇ／Ｌ、ＢＯＤ３０ｍｇ／Ｌ）０．７ｔを加えて得られた希釈原水（透視度２ｃｍ、色度１７０、ｐＨ９．８、ＳＳ２４ｍｇ／Ｌ、ＣＯＤ１８７ｍｇ／Ｌ、ＢＯＤ２２０ｍｇ／Ｌ）２ｔと、３５重量％過酸化水素水［該希釈原水に対して８０重量ｐｐｍ（Ｈ_２Ｏ_２として）］とを曝気槽１０に入れ、空気を供給し、１６時間曝気した。この過酸化水素処理により、液のＣＯＤは９０％以下にまで低減した。
得られた過酸化水素処理液を原水タンク１４に移した後、送液ポンプ１５［（株）荏原製作所製、商品名「Ｐ１２１−６１．５」］により渦流ポンプ１７［（株）ニクニ製、商品名「２５ＵＰＤ」］内に１．０ｍ^３／時の流量で送液すると共に、オゾン発生装置１６［（株）ササクラ製、商品名「ＯＭ−２６０」］で製造したオゾン含有ガスを、１１２３Ｌ／時の流量で渦流ポンプ１７に導入し、気液混合させた［オゾン含有ガス／過酸化水素処理液（容量比）＝１１２／１００；オゾン／過酸化水素処理液（重量比）＝０．２３／１００］。気液混合物をスタティックミキサー１８［日本エンジニアリングプロダクツ（株）製、商品名「ＳｔａｔｉｏｆｌｏＳｔａｔｉｃＭｉｘｅｒ」］を経由して気液分離反応槽１９に底部より導入した。気液分離反応槽１９の液深（高さ）は１６００ｍｍ、内径は１３００ｍｍであり、槽の内部には孔径２ｍｍの孔を有する多孔板３枚が水平に略等間隔で配設されている。気液分離反応槽１９における液面と槽底間の圧力損失は０．１ＭＰａであった。なお、送液ポンプ１５の吐出側（渦流ポンプ１７の吸込側）の圧力（ゲージ圧）は、０．３５ＭＰａ、渦流ポンプ１７の吐出側（スタティックミキサーの入口側）の圧力（ゲージ圧）は０．２５ＭＰａ、スタティックミキサー１８の出口側（気液分離反応槽１９の入口側）の圧力（ゲージ圧）は、０．２２ＭＰａであった。
気液分離反応槽１９で分離された気体は、排オゾン処理機３１に導いて活性炭で処理した後、大気中に排出した。一方、気液分離反応槽１９で分離された液は、渦流ポンプ２０に導き、ここで再度オゾンと攪拌混合し、さらにスタティックミキサー２１で攪拌混合し、気液分離反応槽２２に導入した。渦流ポンプ、スタティックミキサー、気液分離反応槽としては前記と同様のものを使用した。気液分離反応槽２２で分離された気体は、排オゾン処理機３１に導いて処理した。気液分離反応槽２２で分離された液は、過酸化水素分解酵素２３を加えて処理水とし、さらにこれに放流水３０（透視度１６ｃｍ、色度３０、ｐＨ６．８、ＳＳ２２ｍｇ／Ｌ、ＣＯＤ４８ｍｇ／Ｌ、ＢＯＤ３８ｍｇ／Ｌ）を、前記処理水１００容量部に対して３００容量部加え、排水ピット２７に入れた。排水ピット２７内の液は、ｐＨ調整を行った後、河川に放流した。処理水の透視度は１６ｃｍ、色度は６０、ｐＨは９．２、ＳＳは１４ｍｇ／Ｌ、ＣＯＤは１２７ｍｇ／Ｌ、ＢＯＤは１１０ｍｇ／Ｌであり、希釈処理水の透視度は１３ｃｍ、色度は４０、ｐＨは８．０、ＳＳは２７ｍｇ／Ｌ、ＣＯＤは７２ｍｇ／Ｌ、ＢＯＤは８３ｍｇ／Ｌであった。
【００４１】
実施例４
図１に示すフローに沿って染色廃水を処理した。なお、実施例３と同様、過酸化水素処理液を原水タンク１４に移すまではバッチ式で、それ以後は連続式で運転した。
染色廃水（濃厚廃水）（透視度１ｃｍ、色度１７０、ｐＨ１０．１、ＳＳ７ｍｇ／Ｌ、ＣＯＤ３０６ｍｇ／Ｌ、ＢＯＤ３９６ｍｇ／Ｌ）１．３ｔに放流水６（透視度１４ｃｍ、色度３０、ｐＨ６．６、ＳＳ２０ｍｇ／Ｌ、ＣＯＤ４０ｍｇ／Ｌ、ＢＯＤ２９ｍｇ／Ｌ）０．７ｔを加えて得られた希釈原水（透視度２ｃｍ、色度１８０、ｐＨ９．８、ＳＳ２８ｍｇ／Ｌ、ＣＯＤ２１５ｍｇ／Ｌ、ＢＯＤ２１２ｍｇ／Ｌ）２ｔと、３５重量％過酸化水素水［該希釈原水に対して８０重量ｐｐｍ（Ｈ_２Ｏ_２として）］とを曝気槽１０に入れ、空気を供給し、４時間曝気した。この過酸化水素処理により、液のＣＯＤは９０％以下にまで低減した。
得られた過酸化水素処理液を、実施例３と同様にしてオゾン処理し、処理水を得た。この処理水の透視度は１９ｃｍ、色度は７０、ｐＨは９．０、ＳＳは１８ｍｇ／Ｌ、ＣＯＤは１４０ｍｇ／Ｌ、ＢＯＤは１２９ｍｇ／Ｌであった。
次いで、得られた処理水に対して、再度、上記と同様にして、過酸化水素処理及びオゾン処理を施し、処理水を得た。この２回目の処理水の透視度は３０ｃｍ以上、色度は３０、ｐＨは７．５、ＳＳは７ｍｇ／Ｌ、ＣＯＤは１１１ｍｇ／Ｌ、ＢＯＤは１２２ｍｇ／Ｌであった。
【図面の簡単な説明】
【図１】本発明の着色廃水の処理方法の１例を示す概略工程図である。
【符号の説明】
１着色廃水（染色廃水等）
２原水ピット
６放流水
７過酸化水素水
９ブロワ
１０曝気槽
１１散気板
１４原水タンク
１５送液ポンプ
１６オゾン発生装置
１７，２０渦流ポンプ
１８，２１管路内ミキサー
１９，２２気液分離反応槽
２３過酸化水素分解酵素
２５ｐＨ調整液
２７排水ピット
３０放流水
３１排オゾン処理機[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for treating colored wastewater such as dyed wastewater and a colored wastewater treatment apparatus used for the method.
[0002]
[Prior art]
Conventionally, as a method for removing soluble organic substances and dyes contained in coloring wastewater such as dyeing wastewater, a decolorization step of removing dyes using metal ions and a polymer-based flocculant, and a biological method such as an activated sludge treatment method. There is known a method combining a biological oxidation treatment step of decomposing a soluble organic substance by an oxidation method. However, in this method, in addition to using a large amount of chemicals in the decolorization step, a large amount of residues are generated in the coagulation sedimentation processing and pressure flotation processing accompanying the decolorization step, and excess sludge is generated in the biological oxidation treatment step, Treatment of these residues and excess sludge is a major problem.
[0003]
On the other hand, a method of treating colored wastewater with ozone to decolorize it is also known. However, when the colored wastewater is treated only with ozone, although the degree of coloring of the wastewater is reduced, the COD value is not sufficiently reduced, and the BOD value may increase. Therefore, it is necessary to perform a microbial treatment after the ozone treatment (for example, see Patent Literatures 1 and 2), and the treatment of excess sludge becomes a problem as described above. As a method of treating hard-to-decompose wastewater, an accelerated oxidation method in which a small amount of hydrogen peroxide is added during ordinary ozone treatment to perform treatment is known. In this method, decolorization and reduction of COD and BOD are performed. Is inadequate.
[0004]
[Patent Document 1]
JP-A-49-98055
[Patent Document 2]
JP-A-6-254575
[0005]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to efficiently decolorize colored wastewater and reduce COD (chemical oxygen demand) and BOD (biochemical oxygen demand) without discharging a large amount of residue or excess sludge. It is an object of the present invention to provide a method for treating colored wastewater and a device used for the method.
Another object of the present invention is to provide a method for treating colored wastewater, which can efficiently perform oxidation treatment of colored wastewater with ozone, and an apparatus used therefor.
[0006]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object. As a result, when colored wastewater is first subjected to hydrogen peroxide treatment to reduce COD to 90% or less and then subjected to ozone treatment, not only decolorization, It has been found that COD and BOD can be efficiently reduced. In the ozone treatment step, the liquid to be treated is supplied into the vortex pump by applying pressure by a liquid feed pump, and an ozone-containing gas is introduced. The two are stirred and mixed in the vortex pump, and the liquid to be treated and ozone are mixed. The gas-liquid mixture with the contained gas is supplied to a gas-liquid separation reaction tank in which the ratio of the liquid depth (height) to the inner diameter of the tank and the pressure loss between the liquid level in the tank and the tank bottom are within a specific range, and the ozone is supplied. It has been found that when gas-liquid separation is performed together with oxidation, oxidation treatment with ozone can be performed extremely efficiently. The present invention has been completed based on these findings.
[0007]
That is, the present invention provides a hydrogen peroxide treatment step A in which COD is reduced to 90% or less by performing a hydrogen peroxide treatment on colored wastewater, and an ozone treatment step B in which an ozone treatment is performed on the treated liquid subjected to the hydrogen peroxide treatment. And a method for treating colored wastewater.
[0008]
In this treatment method, after the ozone treatment step B, the treatment liquid may be further subjected to one or more cycles of hydrogen peroxide treatment and ozone treatment in this order. The hydrogen peroxide treatment is preferably performed under oxygen aeration.
[0009]
In the ozone treatment step B, the treatment liquid subjected to the hydrogen peroxide treatment is supplied to the vortex pump by applying pressure by a liquid supply pump, and an ozone-containing gas is introduced, and the two are stirred and mixed in the vortex pump. Step B1 may be included. In addition to this, the gas-liquid mixture obtained in Step B1 may be stirred and mixed with an in-line mixer, or the gas-liquid mixture obtained in Step B2 may be further gas-mixed. A step B3 of performing gas-liquid separation together with ozone oxidation in the liquid separation reaction tank may be included. The supply ratio between the ozone-containing gas and the hydrogen peroxide-treated liquid (the former / the latter; the volume ratio) into the vortex pump is, for example, 20/80 or more. The ratio (L / D) of the liquid depth (height) L and the inner diameter D of the tank in the gas-liquid separation reaction tank is, for example, 1.0 to 10, and the liquid level in the gas-liquid separation reaction tank is The pressure loss between the tank bottoms is, for example, 0.05 MPa or more.
[0010]
The present invention is also a method for treating colored wastewater in which colored wastewater is subjected to ozone treatment, wherein an ozone-containing gas is introduced into the vortex pump while supplying the liquid to be treated under pressure by a liquid feed pump. Provided is a method for treating colored wastewater, which includes a step of stirring and mixing both in a vortex pump. This processing method may include a step of further stirring and mixing the gas-liquid mixture obtained by stirring and mixing in the vortex pump with an in-line mixer.
[0011]
The present invention further relates to a method for treating colored wastewater in which colored wastewater is subjected to ozone treatment, wherein a gas-liquid mixture of an ozone-containing gas and a liquid to be treated is treated with a liquid depth (height) L and an inner diameter D of a tank. A step of supplying into a gas-liquid separation reaction tank having a ratio (L / D) of 1.0 to 10 and a pressure loss between the liquid level and the tank bottom of 0.05 MPa or more, and performing gas-liquid separation together with ozone oxidation. And a method for treating colored wastewater.
[0012]
The present invention is still further an apparatus for treating colored wastewater, comprising: a vortex pump for stirring and mixing the liquid to be treated and the ozone-containing gas; and applying pressure to the liquid to be treated in the vortex pump. Provided is a colored wastewater treatment apparatus provided with a liquid feed pump for supplying.
[0013]
The present invention is also an apparatus for treating colored wastewater, which has a supply port for supplying a gas-liquid mixture of an ozone-containing gas and a liquid to be treated, and has a liquid depth (height) L and a tank. The present invention provides a colored wastewater treatment apparatus provided with a gas-liquid separation reaction tank having a ratio (L / D) of 1.0 to 10 to the inner diameter D and a pressure loss between the liquid surface and the tank bottom of 0.05 MPa or more. I do.
[0014]
The present invention further relates to an apparatus for treating colored wastewater, comprising a hydrogen peroxide treatment apparatus for treating colored wastewater with hydrogen peroxide, a hydrogen peroxide treated liquid subjected to hydrogen peroxide treatment, and an ozone-containing liquid. A vortex pump for stirring and mixing the gas, a liquid sending pump for supplying the hydrogen peroxide treatment liquid by applying pressure to the vortex pump, and a gas-liquid mixture obtained by stirring and mixing in the vortex pump. And a gas-liquid separation reactor for separating the gas-liquid mixture obtained by stirring and mixing with the in-line mixer together with the ozone oxidation, with a liquid depth (height). A) a gas-liquid separation reaction tank in which the ratio (L / D) of L to the inner diameter D of the tank is 1.0 to 10 and the pressure loss between the liquid surface and the tank bottom is 0.05 MPa or more. Provide a wastewater treatment device.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic process diagram showing one example of the method for treating colored wastewater of the present invention. In this example, the colored wastewater 1 is introduced from a raw water pit 2 by a pump 3 through a filter 4 and a heat exchanger 5 into an aeration tank 10. The filter 4 is provided for removing SS (residue) in the colored wastewater 1, and the heat exchanger 5 is provided for cooling the colored wastewater 1. Before the aeration tank 10, the discharged water 6 (if necessary) and the hydrogen peroxide solution 7 are added to the colored wastewater 1 by the pump 8, and a mixed solution thereof enters the aeration tank 10. In the aeration tank 10, air is sent by the blower 9 and is aerated by the diffuser plate 11, where hydrogen peroxide treatment is performed. The aeration tank 10 is divided into two tanks, and the supernatant liquid enters the second tank. The colored wastewater in the raw water pit 2 may be referred to as "rich wastewater", and the wastewater plus the discharge water 6 may be referred to as "dilution raw water".
[0016]
As the colored wastewater 1, a wide range of wastewater containing a coloring component can be used. As typical examples, for example, coloring wastewater (dyeing wastewater) from a dyeing process at a dyeing factory, coloring wastewater from a dyeing factory, coloring wastewater discharged at the time of pulp production at a pulp factory, Colored wastewater, colored wastewater from pig farms, colored wastewater from steel plants, and the like.
[0017]
By the hydrogen peroxide treatment, COD elements mainly contained in the colored wastewater are removed, and the COD of the liquid to be treated is reduced. The COD is preferably reduced to 90% or less by this hydrogen peroxide treatment. By providing a hydrogen peroxide treatment step before the ozone treatment step, not only can the amount of ozone used in the ozone treatment step be significantly reduced, but also the COD and The BOD reduction efficiency is greatly improved. It is presumed that this is because hydrogen peroxide converts organic substances in the colored wastewater into substances that are more easily oxidized by ozone. Depending on the type of colored wastewater, the BOD may be increased by the hydrogen peroxide treatment, but the BOD becomes extremely low by the subsequent ozone treatment.
[0018]
Hydrogen peroxide (H ₂ O ₂ ) Is used in an amount of, for example, about 10 to 1,000 ppm by weight, preferably about 20 to 500 ppm by weight, and more preferably about 40 to 300 ppm by weight, based on the liquid to be treated (colored wastewater). The processing temperature is, for example, about 0 to 30 ° C., and the processing can be suitably performed at normal temperature. The processing time is, for example, about 1 to 8 hours, preferably about 2 to 4 hours. The hydrogen peroxide treatment is preferably performed under oxygen aeration. Oxidation efficiency is greatly improved by performing hydrogen peroxide treatment under oxygen aeration. As the oxygen, any of pure oxygen, a mixed gas of oxygen and an inert gas, and air may be used. The amount of aeration is, for example, about 0.008 to 1.7 L / min, preferably about 0.2 to 0.8 L / min, per liter of the liquid to be treated.
[0019]
The colored wastewater that has been subjected to the hydrogen peroxide treatment enters the raw water tank 14 through the filter 13 by the pump 12 from the second tank of the aeration tank 10, and is then subjected to pressure from the raw water tank 14 by the liquid feed pump 15. Then, the mixture is supplied to a gas-liquid separation reaction tank 19 via a vortex pump (mixing pump) 17 and a mixer 18 in a pipeline. At this time, the ozone-containing gas produced by the ozone generator 16 is introduced into the vortex pump 17. The ozone introduced into the vortex pump 17 is stirred and mixed with the liquid to be treated (colored waste water) to form small bubbles, which are then further finely cut by the in-line mixer 18.
[0020]
The liquid feed pump 15 is not particularly limited as long as it is a pump that can send liquid, but a vortex pump or the like is preferable. The vortex pump 17 can introduce a liquid and a gas, give both energy of pressure and speed to the liquid by rotation of the impeller, mix and stir the introduced liquid and the gas, and remove the obtained gas-liquid mixture. The pump is not particularly limited as long as it has a dischargeable structure, and a commercially available vortex turbine pump or the like can be used.
[0021]
The ozone generator 16 is not particularly limited, and a known device can be used. The raw material used for generating ozone may be any of air, oxygen extracted from air, oxygen obtained by electrolysis of water, and the like. High-purity oxygen (eg, 98% oxygen) can also be used. As the in-pipe mixer 18, any mixer provided in the pipe may be used, and a static mixer, a line mixer, or the like can be used. Among them, a static mixer is preferred. The in-pipe mixer 18 is preferably a mixer capable of reducing the bubble diameter to 1000 μm or less.
[0022]
As described above, according to the method in which the liquid feed pump 15 is provided on the suction side of the vortex pump 17 to apply pressure to feed the liquid, the liquid to be treated is forced into the vortex pump 17 by the pressure of the liquid feed pump 15. Since the gas is supplied, the gas-liquid mixture of the liquid to be treated and the ozone-containing gas is smoothly supplied to the in-line mixer 18 even if the supply ratio between the ozone-containing gas and the liquid to be treated (the former / the latter; the volume ratio) is high. , Where the gas and liquid are vigorously stirred and mixed. Therefore, the contact efficiency between ozone and the liquid to be treated is greatly improved, the dissolution efficiency of ozone is also significantly increased, and the oxidation efficiency of ozone in the gas-liquid separation reaction tank is greatly improved. Further, since pressure is applied to the liquid to be treated by the liquid sending pump 15, the amount of dissolved ozone also increases. In addition, when the liquid feed pump is not provided before the vortex pump, when the supply ratio of the ozone-containing gas and the liquid to be treated (the former / the latter; volume ratio) usually exceeds 10/90, the vortex pump generates bubbles. Biting and liquid feeding are not performed smoothly.
[0023]
The supply ratio (the former / the latter; the volume ratio) of the ozone-containing gas and the liquid to be treated (colored wastewater) to the vortex pump 17 is, for example, 20/80 or more, and preferably 30/70 or more (for example, 30/70 or more). 70/30), more preferably 40/60 or more (for example, about 40/60 to 70/30). In the present invention, it is possible to supply more than 200 mg (e.g., 210 to 500 mg, preferably 220 to 500 mg) of ozone to 1 L of the liquid to be treated by selecting the raw material oxygen concentration used in generating ozone. It is possible.
[0024]
The pressure (gauge pressure) on the discharge side of the liquid feed pump 15 (the suction side of the vortex pump 17) is preferably about 0.01 to 0.15 MPa, more preferably about 0.05 to 0.1 MPa. The pressure (gauge pressure) on the discharge side (the inlet side of the in-line mixer) is preferably about 0.01 to 0.15 MPa, more preferably about 0.05 to 0.1 MPa. Is preferably about 0.01 to 0.1 MPa, more preferably about 0.01 to 0.05 MPa, on the outlet side (the inlet side of the gas-liquid separation reaction tanks 19 and 20). Since ozone self-decomposes at a pressure (absolute pressure) of 0.3 MPa or more (total pressure), it is necessary to perform a gas-liquid mixing operation at a pressure lower than the pressure.
[0025]
According to the above method, the liquid to be treated and the ozone-containing gas are efficiently stirred and mixed, so that the size of the bubbles is extremely small. For example, the average bubble diameter may be less than 600 μm (generally about 300 to 500 μm). it can.
[0026]
In the gas-liquid separation reaction tank 19, organic substances and the like in the liquid to be treated are oxidized by ozone, and the gas-liquid mixture is separated into a gas and a liquid. By this ozone treatment, the chromaticity of the liquid to be treated is significantly reduced, and COD and BOD are significantly reduced. In addition to the above, two or more gas-liquid separation reactors may be connected in parallel, or three or more may be used in parallel.
[0027]
The gas-liquid separation reaction tank 19 is provided with a supply port for the gas-liquid mixture and a discharge port for discharging the separated gas and liquid. When the gas-liquid separation reaction tank 19 is in operation, the ratio (L / D) of the liquid depth (height) L to the inner diameter D of the tank is 1.0 to 10 (preferably 1.0 to 10). 2.5, more preferably 1.5 to 2), and the pressure loss between the liquid surface and the tank bottom is 0.05 MPa or more (for example, 0.05 to 0.2 MPa, preferably 0.1 to 0.2 MPa). Are preferred. When such a gas-liquid separation reaction tank is used, the gas-liquid separation and oxidation reaction proceed efficiently even when the height of the reaction tank is low.
[0028]
As a method for adjusting the pressure loss between the liquid surface and the tank bottom to 0.1 MPa or more, for example, one or two or more (for example, about 2 to 5) meshes, perforated plates, dispersion plates, and the like are placed in a reaction tank. And causing a pressure loss in the flow path. By inserting a mesh, a perforated plate, or the like, the piston flow property is improved, and the ozone oxidation efficiency is significantly increased. The pressure loss can be controlled by appropriately adjusting the hole diameter, the number of holes, the number of holes, and the like of the mesh or the perforated plate. The gas-liquid mixture may be introduced from either the upper part or the lower part of the gas-liquid separation reaction tank, but is preferably introduced from the lower part from the viewpoint of increasing efficiency. The gas-liquid separation reaction tank may be of a multi-stage type.
[0029]
The gas separated in the gas-liquid separation reaction tank 19 is treated by an exhaust ozone treatment device 31 and then exhausted. As the waste ozone treatment device 31, a normal ozone treatment device such as a catalyst such as activated carbon or an ozone decomposer using heat can be used.
[0030]
The liquid separated in the gas-liquid separation reaction tank 19 is guided to a vortex pump (mixing pump) 20, where it is again stirred and mixed with ozone, and further stirred and mixed by a mixer 21 in a pipeline. It is introduced into the tank 22. As the vortex pump, the mixer in the pipe, and the gas-liquid separation reaction tank, the same ones as described above can be used. As described above, by repeating gas-liquid mixing by a vortex pump, stirring by a mixer in a pipeline, and a series of operations of reaction and gas-liquid separation in a gas-liquid separation reaction tank twice or more, decolorization and COD and BOD Can be more reliably reduced. In particular, if the hydrogen peroxide treatment is performed again after the ozone treatment, the organic substances in the colored wastewater are converted into substances that are more easily decomposed by the hydrogen peroxide due to the ozone. Is significantly reduced.
[0031]
The gas separated in the gas-liquid separation reaction tank 22 is sent to the waste ozonizer 31 for processing. To the liquid separated in the gas-liquid separation reaction tank 22, hydrogen peroxide decomposing enzyme 23 is added by a pump 24 on the way, and further, effluent water 30 is added if necessary, and flows into a drain pit 27. In the drain pit 27, a pH adjusting solution 25 (for example, an acid such as sulfuric acid) is added by a pump 26 to adjust the pH. In the figure, 28 is a stirrer and 29 is a pH meter. The inside of the drain pit 27 is divided into two, and the supernatant liquid enters the second tank, from which it is discharged into the river. In addition, what added the hydrogen peroxide decomposing enzyme to the liquid isolate | separated in the gas-liquid separation reaction tank may only be called "process water." The treated water plus the effluent may be simply referred to as "diluted treated water".
[0032]
When the same hydrogen peroxide treatment and ozone treatment as described above are repeated once or more in this order on the liquid separated in the gas-liquid separation reaction tank 22, the decolorizing effect and the COD and BOD reduction effects are remarkable. Increase. In the second and subsequent hydrogen peroxide treatments, it is not always necessary to reduce the COD to 90% or less.
[0033]
【The invention's effect】
According to the method for treating colored wastewater of the present invention, decolorization and reduction of COD and BOD can be performed on a wide range of colored wastewater without discharging a large amount of residue or excess sludge. In addition, since the colored wastewater is subjected to hydrogen peroxide treatment to reduce COD to some extent (for example, to 90% or less) and then to ozone treatment, not only can the amount of ozone used in the ozone treatment step be reduced, but also decolorization can be achieved. COD and BOD reduction efficiency is also improved. If, after the ozone treatment step, the treatment liquid is further subjected to one or more cycles of hydrogen peroxide treatment and ozone treatment in this order, decolorization and the efficiency of COD and BOD reduction are dramatically improved. When the hydrogen peroxide treatment is performed under oxygen aeration, the oxidizing power of hydrogen peroxide is increased, and the efficiency of reducing COD and the like is further improved.
[0034]
When mixing colored wastewater with an ozone-containing gas in a vortex pump, if the colored wastewater is introduced into the vortex pump by applying pressure using a liquid feed pump, the gas-liquid mixture in the vortex pump is forced , The air bubbles are less likely to be caught and the gas-liquid ratio can be greatly increased. As a result, for example, the gas-liquid contact efficiency and the ozone dissolution efficiency in the mixer in the pipeline and the gas-liquid separation reaction tank are increased, and the oxidation reaction efficiency (decolorization and COD / BOD reduction efficiency) by ozone is also greatly improved.
[0035]
The ozone treatment of the colored wastewater was carried out in such a manner that the ratio (L / D) of the liquid depth (height) L to the inner diameter D of the tank was 1.0 to 10 and the pressure loss between the liquid level in the tank and the tank bottom was 0. When the reaction is performed using a gas-liquid separation reaction tank having a pressure of 0.05 MPa or more, the ozone oxidation efficiency can be increased even if the height of the reaction tank is low, and gas-liquid separation proceeds efficiently.
[0036]
The colored wastewater treatment apparatus of the present invention is suitably used for the method of treating colored wastewater of the present invention.
[0037]
【Example】
Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The transparency is the method of JIS K0102-9, the chromaticity is the method of JIS K0101-10.1, the SS is the method of JIS K0102-14.1, the COD is the method of JIS K0102-17, and the BOD is JIS. It measured according to the method of K0102-21,32.3.
[0038]
Example 1
The dyeing wastewater was treated according to the flow shown in FIG. In this example, only the hydrogen peroxide treatment step is described.
58 L of diluted raw water (transparency 1 cm, chromaticity 750, pH 10.2, SS 9 mg / L, COD 380 mg / L, BOD 240 mg / L) obtained by adding effluent 6 to dyeing waste water 1 (concentrated waste water), and 35% by weight 60 ml of a hydrogen peroxide solution was put into the aeration tank 10, air was supplied at a flow rate of 20 l / min, and aeration was performed for 3.5 hours. As a result, a liquid having a transparency of 1 cm, a chromaticity of 830, a pH of 9.7, an SS of 16 mg / L, a COD of 304 mg / L, and a BOD of 338 mg / L was obtained. COD was reduced to 80%.
[0039]
Example 2
The working examples were the same as those of the diluent raw water except that a fluorometer of 1 cm, chromaticity of 870, pH 10.2, SS of 20 mg / L, COD of 380 mg / L, BOD of 220 mg / L was used, and 30 ml of 35% by weight hydrogen peroxide was used. The same operation as in Example 1 was performed. As a result, a liquid having a transparency of 1 cm, a chromaticity of 930, a pH of 9.8, an SS of 29 mg / L, a COD of 334 mg / L, and a BOD of 428 mg / L was obtained. COD was reduced to 87.9%.
[0040]
Example 3
The dyeing wastewater was treated according to the flow shown in FIG. The operation was performed in a batch system until the hydrogen peroxide treatment liquid was transferred to the raw water tank 14, and thereafter in a continuous system.
Dyeing waste water 1 (concentrated waste water) (transparency 1 cm, chromaticity 330, pH 10.1, SS 11 mg / L, COD 301 mg / L, BOD 309 mg / L) 1.3 t and discharge water 6 (transparency 15 cm, chromaticity 50, pH 6. 6, SS30mg / L, COD45mg / L, BOD30mg / L) Diluted raw water obtained by adding 0.7t (transparency 2cm, chromaticity 170, pH9.8, SS24mg / L, COD187mg / L, BOD220mg / L) 2t and 35% by weight aqueous hydrogen peroxide [80 ppm by weight (H ₂ O ₂ )] Was placed in the aeration tank 10, air was supplied, and aeration was performed for 16 hours. By this hydrogen peroxide treatment, the COD of the liquid was reduced to 90% or less.
After transferring the obtained hydrogen peroxide-treated solution to the raw water tank 14, a vortex pump 17 [manufactured by Nikuni Co., Ltd., using a liquid sending pump 15 [manufactured by Ebara Corporation, trade name "P121-61.5"]] 1.0m within the product name "25UPD"] ³ / Hour, and the ozone-containing gas produced by the ozone generator 16 (trade name “OM-260” manufactured by Sasakura Co., Ltd.) is introduced into the vortex pump 17 at a flow rate of 1123 L / hour. Gas-liquid mixture [ozone-containing gas / hydrogen peroxide treatment liquid (volume ratio) = 112/100; ozone / hydrogen peroxide treatment liquid (weight ratio) = 0.23 / 100]. The gas-liquid mixture was introduced into the gas-liquid separation reaction tank 19 from the bottom via a static mixer 18 [trade name “Statioflo Static Mixer” manufactured by Nippon Engineering Products Co., Ltd.]. The liquid depth (height) of the gas-liquid separation reaction tank 19 is 1600 mm and the inside diameter is 1300 mm. Inside the tank, three perforated plates having holes with a diameter of 2 mm are horizontally arranged at substantially equal intervals. The pressure loss between the liquid level and the tank bottom in the gas-liquid separation reaction tank 19 was 0.1 MPa. The pressure (gauge pressure) on the discharge side (suction side of the vortex pump 17) of the liquid feed pump 15 is 0.35 MPa, and the pressure (gauge pressure) on the discharge side (the inlet side of the static mixer) of the vortex pump 17 is 0. The pressure (gauge pressure) on the outlet side of the static mixer 18 (the inlet side of the gas-liquid separation reaction tank 19) was 0.22 MPa.
The gas separated in the gas-liquid separation reaction tank 19 was guided to a waste ozone treatment device 31, treated with activated carbon, and then discharged into the atmosphere. On the other hand, the liquid separated in the gas-liquid separation reaction tank 19 was led to a vortex pump 20, where it was again mixed with ozone by stirring, further mixed with a static mixer 21, and introduced into the gas-liquid separation reaction tank 22. The vortex pump, the static mixer, and the gas-liquid separation reaction tank used were the same as those described above. The gas separated in the gas-liquid separation reaction tank 22 was guided to an exhaust ozone processor 31 for processing. The liquid separated in the gas-liquid separation reaction tank 22 is treated with hydrogen peroxide decomposing enzyme 23 to obtain treated water, and further discharged with water 30 (transparency 16 cm, chromaticity 30, pH 6.8, SS 22 mg / L, COD 48 mg). / L, BOD 38 mg / L) was added to the drainage pit 27 by adding 300 parts by volume to 100 parts by volume of the treated water. The liquid in the drain pit 27 was discharged into a river after pH adjustment. The transparency of the treated water is 16 cm, the chromaticity is 60, the pH is 9.2, the SS is 14 mg / L, the COD is 127 mg / L, the BOD is 110 mg / L, the transparency of the diluted treated water is 13 cm, the chromaticity Was 40, pH was 8.0, SS was 27 mg / L, COD was 72 mg / L, and BOD was 83 mg / L.
[0041]
Example 4
The dyeing wastewater was treated according to the flow shown in FIG. As in the case of Example 3, the operation was performed in a batch system until the hydrogen peroxide treatment liquid was transferred to the raw water tank 14, and thereafter in a continuous system.
Dyeing wastewater (concentrated wastewater) (perspective degree 1 cm, chromaticity 170, pH 10.1, SS7 mg / L, COD 306 mg / L, BOD 396 mg / L) 1.3 t and discharge water 6 (transparency 14 cm, chromaticity 30, pH 6.6) , SS 20 mg / L, COD 40 mg / L, BOD 29 mg / L) 0.7 t of diluted raw water (transparency 2 cm, chromaticity 180, pH 9.8, SS 28 mg / L, COD 215 mg / L, BOD 212 mg / L) 2 t And 35% by weight of hydrogen peroxide [80 ppm by weight (H ₂ O ₂ )] Was placed in the aeration tank 10, air was supplied, and aeration was performed for 4 hours. By this hydrogen peroxide treatment, the COD of the liquid was reduced to 90% or less.
The obtained hydrogen peroxide-treated solution was treated with ozone in the same manner as in Example 3 to obtain treated water. The transparency of this treated water was 19 cm, the chromaticity was 70, the pH was 9.0, the SS was 18 mg / L, the COD was 140 mg / L, and the BOD was 129 mg / L.
Next, the obtained treated water was again subjected to a hydrogen peroxide treatment and an ozone treatment in the same manner as described above to obtain treated water. The transparency of the second treated water was 30 cm or more, the chromaticity was 30, the pH was 7.5, the SS was 7 mg / L, the COD was 111 mg / L, and the BOD was 122 mg / L.
[Brief description of the drawings]
FIG. 1 is a schematic process diagram showing one example of a method for treating colored wastewater of the present invention.
[Explanation of symbols]
1 Coloring wastewater (dyeing wastewater, etc.)
2 Raw water pit
6 Discharge water
7 Hydrogen peroxide solution
9 Blower
10 Aeration tank
11 diffuser plate
14 Raw water tank
15 Liquid pump
16 Ozone generator
17,20 vortex pump
18,21 In-line mixer
19,22 Gas-liquid separation reaction tank
23 Hydrogen peroxide degrading enzyme
25 pH adjusting solution
27 Drainage pit
30 Discharge water
31 Waste ozone treatment machine

【０００７】
すなわち、本発明は、着色廃水にオゾン処理を施す着色廃水の処理方法であって、渦流ポンプ内に、被処理液を送液ポンプにより圧力を加えて供給すると共にオゾン含有ガスを導入し、該渦流ポンプ内で両者を攪拌混合する工程Ｂ１を含むオゾン処理工程Ｂを有する着色廃水の処理方法を提供する。[0007]
That is, the present invention relates to a method for treating colored wastewater in which colored wastewater is subjected to ozone treatment, in which an ozone-containing gas is introduced into the vortex pump while supplying the liquid to be treated under pressure by a liquid feed pump. Provided is a method for treating colored wastewater having an ozone treatment step B including a step B1 of stirring and mixing both in a vortex pump .

【０００８】
この処理方法において、オゾン処理工程Ｂの前に、着色廃水に過酸化水素処理を施す過酸化水素処理工程Ａを設け、この工程Ａで得られた処理液を工程Ｂ１の被処理液として用いてもよい。 [0008]
In this treatment method, before the ozone treatment step B, a hydrogen peroxide treatment step A for subjecting the colored wastewater to hydrogen peroxide treatment is provided, and the treatment liquid obtained in this step A is used as the liquid to be treated in step B1. Is also good.

【０００９】
この処理方法において、オゾン処理工程Ｂの後、この処理液に対してさらに過酸化水素処理とオゾン処理とをこの順序で１サイクル以上施してもよい。前記過酸化水素処理は酸素曝気下で行うのが好ましい。 [0009]
In this treatment method, after the ozone treatment step B, the treatment liquid may be further subjected to one or more cycles of hydrogen peroxide treatment and ozone treatment in this order. The hydrogen peroxide treatment is preferably performed under oxygen aeration.

【００１０】
前記処理方法において、渦流ポンプ内へのオゾン含有ガスと被処理液との供給比（前者／後者；容量比）は、例えば２０／８０以上である。また、渦流ポンプ吐出側の圧力（ゲージ圧）は、０．０１〜０．１５ＭＰａであるのが好ましい。 [0010]
In the processing method, the supply ratio (the former / the latter; the volume ratio) of the ozone-containing gas and the liquid to be processed into the vortex pump is, for example, 20/80 or more. The pressure (gauge pressure) on the discharge side of the vortex pump is preferably 0.01 to 0.15 MPa.

【００１１】
前記処理方法において、オゾン処理工程Ｂは、工程Ｂ１において渦流ポンプ内で攪拌混合して得られた気液混合物をさらに管路内ミキサーで攪拌混合する工程Ｂ２を含んでいてもよい。 [0011]
In the above treatment method, the ozone treatment step B may include a step B2 of further stirring and mixing the gas-liquid mixture obtained by stirring and mixing in the vortex pump in the step B1 with an in-line mixer .

【００１２】
オゾン処理工程Ｂは、オゾン含有ガスと被処理液との気液混合物を気液分離反応槽内でオゾン酸化と共に気液分離する工程Ｂ３を含んでいてもよい。前記気液分離反応槽における液深Ｌと槽の内径Ｄとの比（Ｌ／Ｄ）は、例えば１．０〜１０であり、気液分離反応槽内の液面と槽底間の圧力損失は、例えば０．０５ＭＰａ以上である。 [0012]
The ozone treatment step B may include a step B3 of gas-liquid separation of the gas-liquid mixture of the ozone-containing gas and the liquid to be treated together with ozone oxidation in the gas-liquid separation reaction tank . The ratio (L / D) of the liquid depth L in the gas-liquid separation reaction tank to the inner diameter D of the tank is, for example, 1.0 to 10, and the pressure loss between the liquid level in the gas-liquid separation reaction tank and the tank bottom. Is, for example, 0.05 MPa or more.

【００１３】
本発明は、また、着色廃水を処理するための装置であって、被処理液とオゾン含有ガスとを攪拌混合するための渦流ポンプと、前記被処理液を渦流ポンプ内に圧力を加えて供給するための送液ポンプとを備えた着色廃水処理装置を提供する。前記着色廃水処理装置は、さらに、（ｉ）着色廃水に過酸化水素処理を施す過酸化水素処理装置、（ｉｉ）渦流ポンプ内で攪拌混合して得られた気液混合物をさらに攪拌混合する管路内ミキサー、又は（ｉｉｉ）オゾン含有ガスと被処理液との気液混合物を供給するための供給口を有し、液深Ｌと槽の内径Ｄとの比（Ｌ／Ｄ）が１．０〜１０であり且つ槽内の液面と槽底間の圧力損失が０．０５ＭＰａ以上となる気液分離反応槽を備えていてもよい。 [0013]
The present invention is also an apparatus for treating colored wastewater , comprising: a vortex pump for stirring and mixing a liquid to be treated and an ozone-containing gas; and supplying the liquid to be treated by applying pressure into the vortex pump. To provide a colored wastewater treatment apparatus provided with a liquid sending pump for performing the treatment . The colored wastewater treatment apparatus further comprises (i) a hydrogen peroxide treatment apparatus for performing a hydrogen peroxide treatment on the colored wastewater, and ( ii ) a pipe for further stirring and mixing the gas-liquid mixture obtained by stirring and mixing in the vortex pump. A mixer in the road or ( iii ) a supply port for supplying a gas-liquid mixture of the ozone-containing gas and the liquid to be treated, wherein the ratio (L / D) of the liquid depth L to the inner diameter D of the tank is 1. A gas-liquid separation reaction tank having a pressure loss of 0 to 10 and a pressure loss between the liquid level in the tank and the tank bottom of 0.05 MPa or more may be provided.

【０００７】
すなわち、本発明は、着色廃水にオゾン処理を施す着色廃水の処理方法であって、（１）渦流ポンプ内に、被処理液を送液ポンプにより圧力を加えて供給すると共にオゾン含有ガスを、オゾン含有ガスと被処理液との供給比（前者／後者；容量比）が２０／８０以上となるように導入し、該渦流ポンプ内で両者を攪拌混合する工程Ｂ１と、（２）オゾン含有ガスと被処理液との気液混合物を気液分離反応槽内で、該気液分離反応槽における液深Ｌと槽の内径Ｄとの比（Ｌ／Ｄ）が１．０〜１０であり且つ該気液分離反応槽内の液面と槽底間の圧力損失が０．０５ＭＰａ以上の条件で、オゾン酸化と共に気液分離する工程Ｂ３とを含むオゾン処理工程Ｂを有する着色廃水の処理方法を提供する。[0007]
That is, the present invention is a method for treating colored wastewater in which colored wastewater is subjected to ozone treatment. (1) A liquid to be treated is supplied into a vortex pump by applying pressure by a liquid supply pump, and an ozone-containing gas is supplied to the vortex pump . feed ratio of ozone containing gas and the liquid to be treated (the former / the latter; volume ratio) was introduced so that the 20/80 or more, and step B1 of mixing and stirring both in the vortex flow within the pump, (2) containing ozone A gas-liquid mixture of a gas and a liquid to be treated is placed in a gas-liquid separation reaction tank, and the ratio (L / D) of the liquid depth L to the inner diameter D of the tank in the gas-liquid separation reaction tank is 1.0 to 10; and the pressure loss between the liquid surface and the bottom of the tank of the gas-liquid separation reaction vessel under the above conditions 0.05 MPa, the processing method of the colored wastewater with ozone treatment step B and a step B3 of gas-liquid separation with ozone oxidation I will provide a.

【００１０】
前記処理方法において、渦流ポンプ吐出側の圧力（ゲージ圧）は、０．０１〜０．１５ＭＰａであるのが好ましい。[0010]
In the processing method, the pressure (gauge pressure) on the discharge side of the vortex pump is preferably 0.01 to 0.15 MPa.

Claims

Colored wastewater comprising a hydrogen peroxide treatment step A for subjecting the colored wastewater to hydrogen peroxide treatment to reduce COD to 90% or less, and an ozone treatment step B for subjecting the treated liquid subjected to the hydrogen peroxide treatment to ozone treatment. Processing method.

The method for treating colored wastewater according to claim 1, wherein after the ozone treatment step B, the treatment liquid is further subjected to one or more cycles of a hydrogen peroxide treatment and an ozone treatment in this order.

The method for treating colored wastewater according to claim 1 or 2, wherein the hydrogen peroxide treatment is performed under oxygen aeration.

The ozone treatment step B is a step in which the treatment liquid subjected to the hydrogen peroxide treatment is supplied to the vortex pump by applying pressure by a liquid feed pump, an ozone-containing gas is introduced, and the two are stirred and mixed in the vortex pump. The method for treating colored wastewater according to claim 1, which comprises B1.

The method for treating colored wastewater according to claim 4, wherein the supply ratio of the ozone-containing gas and the hydrogen peroxide treatment liquid into the vortex pump (the former / the latter; the volume ratio) is 20/80 or more.

The method for treating colored wastewater according to claim 4, wherein the ozone treatment step B includes a step B2 of stirring and mixing the gas-liquid mixture obtained in the step B1 with an in-line mixer.

The method for treating colored wastewater according to claim 6, wherein the ozone treatment step B includes a step B3 of gas-liquid separation of the gas-liquid mixture obtained in the step B2 together with ozone oxidation in a gas-liquid separation reaction tank.

The ratio (L / D) of the liquid depth L to the inner diameter D of the tank in the gas-liquid separation reaction tank is 1.0 to 10 and the pressure loss between the liquid surface and the tank bottom in the gas-liquid separation reaction tank is 0. The method for treating colored wastewater according to claim 7, wherein the pressure is 0.05 MPa or more.

This is a method for treating colored wastewater in which colored wastewater is subjected to ozone treatment, and the ozone-containing gas is introduced into the vortex pump while supplying the liquid to be treated by applying pressure by a liquid feed pump, and the two are mixed in the vortex pump. A method for treating colored wastewater including a step of stirring and mixing.

The method for treating colored wastewater according to claim 9, further comprising a step of further stirring and mixing the gas-liquid mixture obtained by stirring and mixing in the vortex pump with an in-line mixer.

A method for treating colored wastewater in which colored wastewater is subjected to ozone treatment, wherein a gas-liquid mixture of an ozone-containing gas and a liquid to be treated is treated with a ratio (L / D) of a liquid depth L to an inner diameter D of a tank of 1.0. A method for treating colored wastewater comprising supplying to a gas-liquid separation reaction tank having a pressure drop between the liquid level in the tank and the tank bottom of 0.05 MPa or more and performing gas-liquid separation together with ozone oxidation. .

An apparatus for treating colored wastewater, comprising a vortex pump for stirring and mixing a liquid to be treated and an ozone-containing gas, and a liquid feed pump for supplying the liquid to be treated by applying pressure to the vortex pump. And a colored wastewater treatment device.

An apparatus for treating colored wastewater, which has a supply port for supplying a gas-liquid mixture of an ozone-containing gas and a liquid to be treated, and has a ratio (L / D) between a liquid depth L and an inner diameter D of a tank. ) Is 1.0 to 10 and the pressure loss between the liquid level in the tank and the tank bottom is 0.05 MPa or more.

A device for treating colored wastewater, wherein a hydrogen peroxide treatment device that performs a hydrogen peroxide treatment on the colored wastewater, and a stirring and mixing of the hydrogen peroxide treated liquid and the ozone-containing gas that are subjected to the hydrogen peroxide treatment. A vortex pump, a liquid feed pump for supplying the hydrogen peroxide-treated solution by applying pressure to the vortex pump, and a pipeline for further stirring and mixing the gas-liquid mixture obtained by stirring and mixing in the vortex pump. An inner mixer and a gas-liquid separation reaction tank for separating a gas-liquid mixture obtained by stirring and mixing with an in-line mixer together with ozone oxidation, wherein a ratio of height L to inner diameter D (L / A colored wastewater treatment apparatus comprising: a gas-liquid separation reaction tank wherein D) is 1.0 to 10 and the pressure loss between the liquid level in the tank and the tank bottom is 0.05 MPa or more.