JP3867326B2

JP3867326B2 - Ozone treatment method for activated sludge process water

Info

Publication number: JP3867326B2
Application number: JP28719896A
Authority: JP
Inventors: 康成佐々木; 崇行森岡; 本山　　信行; 龍太郎高橋
Original assignee: Fuji Electric Systems Co Ltd
Current assignee: Fuji Electric Co Ltd
Priority date: 1996-10-30
Filing date: 1996-10-30
Publication date: 2007-01-10
Anticipated expiration: 2016-10-30
Also published as: JPH10128377A

Description

【０００１】
【産業上の利用分野】
本発明は、有機性排水を生物学的方法と物理化学的方法の組み合わせで処理する方法であって、特に余剰汚泥の生成を抑制する処理方法に関する。
【０００２】
【従来の技術】
下水や生活排水、有機性工場排水等を活性汚泥法に代表される生物学的な方法で処理する場合、微生物の増殖にともなって余剰汚泥が発生する。この余剰汚泥の処理方法としては、脱水、埋め立てが一般的であるが、脱水機が高価で操作も面倒であることや、埋め立て用地が不足していること等の理由から、できるだけ余剰汚泥を発生させない排水処理法が求められている。
【０００３】
この要求に適した方法として、特開平６−２０６０８８号公報に生物学的処理法にオゾン処理法を組み合わせた余剰汚泥を発生させない排水処理法が記載されている。この公報の方法は、好気性微生物を含む活性汚泥の存在下で、有機性排液を好気性処理する方法において、被処理液中のＢＯＤの同化により増殖する汚泥量よりも多い量の活性汚泥を好気性処理系から引抜き、引抜き汚泥をオゾン処理したのち好気性処理系に導入することを特長とする有機性排液の好気性処理方法である。この方法では、活性汚泥の一部をオゾン処理することにより、微生物の細胞壁を破壊し、微生物を生物分解可能な有機物に変換して再度処理を行うので、有機物の分解が促進され汚泥が発生しないことになる。生物処理とオゾン処理の特長を組み合わせた優れた着想である。
【０００４】
【発明が解決しようとする課題】
しかしながら、特開平６−２０６０８８号公報に記載された処理法では、微生物による分解が困難な溶解性の有機物が次第に反応槽内に蓄積し、一部が処理水に含まれて流出するため、処理水中の溶解性ＣＯＤやＴＯＣが高くなる問題がある。例えばこの方法で下水を処理した場合、処理水中の溶解性ＣＯＤは通常の活性汚泥法処理水のＣＯＤの２倍程度となってしまう。この様な高いＣＯＤの処理水が放流されることは環境保護の観点から大きな問題であった。
【０００５】
本発明は上述の点に鑑みてなされたものであり、その目的は、生物処理とオゾン処理を組み合わせた処理において、余剰汚泥が発生せず、しかも処理水ＣＯＤが低い処理方法を提供することにある。
【０００６】
【課題を解決するための手段】
上記の課題解決のために、本発明者らは活性汚泥を活性汚泥処理系（本発明では、前段の処理系が無酸素条件のように好気性以外の条件を有する場合も成立するので、従来の「好気性処理系」という表現を「活性汚泥処理系」と変更して記載する）から引抜き、この引抜き汚泥をオゾン処理したのちに活性汚泥処理系に導入するという処理方法について研究開発を行い、処理水に含まれるＣＯＤ成分は、微生物による分解が困難であることから、オゾンの強力な酸化作用による分解が必要で、しかも処理効果を上げるためには、オゾンの酸化作用を促進する条件下でのオゾン酸化が必要であるとの結論を得た。また、水質によっては、オゾンの酸化作用を促進する条件下でのオゾン酸化によって、生物分解可能な溶解性有機物が生成する場合もあるので、その後さらに生物処理を行うことが望ましいこともあるとの結論に達した。
【００１１】
これらの知見を基に、上記の課題を解決するために、次に示す４種類の具体的な処理方法を提供する。以下に順次これらの処理方法を説明する。本発明の第１の処理法は、主として生物反応槽と最終沈殿池からなる活性汚泥処理系から活性汚泥を引抜き、引抜き汚泥をオゾン処理したのち活性汚泥処理系に導入する処理において、その後段で前記活性汚泥処理系からの溶解性ＣＯＤが高い処理水のオゾン処理を行い、さらにこの水を生物処理し、後段の生物処理装置から発生する汚泥を前記生物反応槽に返送する処理法である。
【００１２】
この処理法では、オゾン処理で前記処理水に含まれていた生物難分解性の溶解性有機物を酸化分解した後に、生物処理でオゾン酸化によって生成した中間体を除去しＣＯＤ濃度を低減する。また、後段の生物処理装置から発生する汚泥を前記生物反応槽に返送し処理することによって系全体としての汚泥の発生を抑制する。
【００１３】
本発明の第２の処理法は、主として生物反応槽と最終沈殿池からなる活性汚泥処理系から活性汚泥を引抜き、引抜き汚泥をオゾン処理したのち活性汚泥処理系に導入する処理において、その後段で前記活性汚泥処理系からの溶解性ＣＯＤが高い処理水を紫外線照射とオゾン処理の併用で処理し、さらにこの水を生物処理し、後段の生物処理装置から発生する汚泥を前記生物反応槽に返送する処理法である。
【００１４】
この処理法では、紫外線はオゾンに作用して強力な酸化作用を有するＯＨラジカルの生成を促進する効果があるので、紫外線照射とオゾン処理との併用処理を行えば、強い酸化力によって、前記処理水に含まれていた生物難分解性の溶解性有機物が酸化分解され、ＣＯＤ濃度が大幅に低減される処理をした後に、生物処理で前記併用処理によって生成した中間体を除去しＣＯＤ濃度を低減する。また、後段の生物処理装置から発生する汚泥を前記生物反応槽に返送し処理することによって系全体としての汚泥の発生を抑制する。
【００１５】
本発明の第３の処理法は、主として生物反応槽と最終沈殿池からなる活性汚泥処理系から活性汚泥を引抜き、引抜き汚泥をオゾン処理したのち活性汚泥処理系に導入する処理において、その後段で前記活性汚泥処理系からの溶解性ＣＯＤが高い処理水に過酸化水素水を添加しつつオゾン処理を行い、さらにこの水を生物処理し、後段の生物処理装置から発生する汚泥を前記生物反応槽に返送する処理法である。
【００１６】
この処理法では、過酸化水素はオゾンに作用して強力な酸化作用を有するＯＨラジカルの生成を促進する効果があるので、過酸化水素水とオゾン処理との併用処理を行えば、強い酸化力によって、前記処理水に含まれていた生物難分解性の溶解性有機物が酸化分解され、ＣＯＤ濃度が大幅に低減される処理をした後に、生物処理で前記併用処理によって生成した中間体を除去しＣＯＤ濃度を低減する。また、後段の生物処理装置から発生する汚泥を前記生物反応槽に返送し処理することによって系全体としての汚泥の発生を抑制する。
【００１７】
本発明の第４の処理法は、主として生物反応槽と最終沈殿池からなる活性汚泥処理系から活性汚泥を引抜き、引抜き汚泥をオゾン処理したのち活性汚泥処理系に導入する処理において、その後段で前記活性汚泥処理系からの溶解性ＣＯＤが高い処理水をオゾン処理と不溶性の光触媒処理の併用で処理し、さらにこの水を生物処理し、後段の生物処理装置から発生する汚泥を前記生物反応槽に返送する処理法である。
【００１８】
この処理法では、光触媒は有機物をオゾン酸化した時に生成する中間体を光の照射条件下で効率良く分解する作用があるので、オゾン処理と不溶性の光触媒処理との併用処理を行えば、前記処理水に含まれていた生物難分解性の溶解性有機物を、オゾンによる酸化分解と一部中間体の生成、その中間体の光触媒による分解の経路で除去され、ＣＯＤ濃度が大幅に低減される処理をした後に、生物処理で前記併用処理において残存した中間体を除去しＣＯＤ濃度を低減する。また、後段の生物処理装置から発生する汚泥を前記生物反応槽に返送し処理することによって系全体としての汚泥の発生を抑制する。
【００１９】
【発明の実施の形態】
以下、本発明による処理の実施例を図面を参照して説明する。図１は下水処理を目的とした処理法の参考例を示すフロー図である。図１において、この処理法は、生物反応槽２と最終沈殿池３からなる下水１の活性汚泥処理系、引抜汚泥ポンプ７と汚泥用オゾン処理槽１０及びオゾン発生機８からなる汚泥のオゾン処理系、さらに水用オゾン処理槽１３と紫外線ランプ１２からなる水のオゾン処理系の三つの系から構成されている。このうち、下水の活性汚泥処理系と汚泥のオゾン処理系は特開平６−２０６０８８号公報に記載された処理法を下水処理に適用した形態となっている。
【００２０】
この従来技術の部分を簡単に説明する。下水１は生物反応槽２内で散気装置４から空気を供給されつつ活性汚泥で処理され、最終沈殿池３において固液分離がなされる。また、汚泥は返送汚泥ポンプ５を経て返送汚泥６として生物反応槽２に返されるが、その一部は引抜汚泥ポンプ７を介して汚泥用オゾン処理槽１０に送られ、ここでオゾン処理を受けた後に生物反応槽２に導入される。オゾン９ａの添加量は流入下水量を基準にすると、およそ１０〜２０ｍｇ／Ｌ程度である。この汚泥用オゾン処理槽１０では活性汚泥を構成する微生物の細胞壁が破壊され、オゾン処理汚泥１１は微生物処理可能な有機物として生物反応槽２に導入され、大部分が水や炭酸ガスまで分解される。したがって、この活性汚泥処理系と汚泥のオゾン処理系からなる従来技術の部分からは汚泥が発生しない。
【００２１】
図１の処理法の特徴は前記処理系の後段に、紫外線ランプ１２を備えた水用オゾン処理槽１３を設けた点にあり、添加するオゾン９ｂはオゾン発生機８から得ている。処理機能を説明すると、最終沈殿池３を経た水は溶解性のＣＯＤが高い状態で水用オゾン処理槽１３に流入し、紫外線ランプ１２から紫外線照射を受けながらオゾン酸化処理される。紫外線照射量は水質にもよるが、１００〜５００Ｗ・秒／ｍ³ 程度である。紫外線はオゾンに作用して強力な酸化作用を有するＯＨラジカルの生成を促進する効果があるので、この槽内において流入したＣＯＤ成分は強い酸化を受け除去される。実験結果によれば、前述の条件でＣＯＤ除去率は４０％以上であり、オゾン添加量は５〜２０ｍｇ／Ｌ程度、処理時間は１０〜６０分程度である。添加するオゾン濃度は２０〜２００ｇ／Ｎｍ³ 程度で、オゾン濃度を濃くすると、反応速度が速くなる、発泡が少なくなる等の利点がある。ここでのオゾン利用効率は９０％以上であるが、若干の排オゾン１４が発生するので、これは別途排オゾン処理装置で処理する。また、こうした処理では同時に水中の色度成分もオゾン酸化により除去されるので、色度が低く透明感が高くＣＯＤも除去されたオゾン処理水１５が得られる。
【００２２】
なお、図１では水用オゾン処理槽１３の中に紫外線ランプ１２を浸漬した形態を示したが、オゾン処理槽と紫外線ランプ照射部を分離し、オゾン添加後に溶存オゾンが残存している条件で紫外線を照射する方法でも同様の効果が得られる。この場合、オゾン処理槽と紫外線ランプ照射部の間で、被処理水を循環させることもある。また、これまでは生物反応槽２は好気性処理として説明したが、間欠曝気により、好気、無酸素処理を行っている場合にも本実施例は成立する。この条件は以下の図２から図７の処理法においても同様である。
【００２３】
次に、別の処理法の参考例を図面を参照して説明する。図２は下水処理を目的とした別の処理法の参考例を示すフロー図である。図２の処理法は基本的には図１の処理法に類似しており、異なる点はＣＯＤの高い生物処理水を、過酸化水素水を添加しつつオゾン処理している点にある。したがって、説明はその点に限定し、前段にあたる下水の活性汚泥処理系と汚泥のオゾン処理系の説明は省略する。
【００２４】
図２の処理法の特徴は前記処理系の後段に、過酸化水素水貯留槽１６に貯留した過酸化水素水を薬注ポンプ１７を用いて注入しつつ、水用オゾン処理槽１３においてオゾン処理を行う点にあり、添加するオゾン９ｂはオゾン発生機８から得ている。処理機能を説明すると、最終沈殿池３を経た水は溶解性のＣＯＤが高い状態で水用オゾン処理槽１３に流入し、過酸化水素存在下でオゾン酸化処理される。過酸化水素添加量は水質にもよるが、１０〜３０ｍｇ／Ｌ程度である。過酸化水素はオゾンに作用して強力な酸化作用を有するＯＨラジカルの生成を促進する効果があるので、この槽内において流入したＣＯＤ成分は強い酸化を受け除去されるのである。ＣＯＤ除去率は４０％以上であり、オゾン添加量は５〜５０ｍｇ／Ｌ程度、処理時間は５〜３０分程度である。添加するオゾン濃度は２０〜２００ｇ／Ｎｍ³ 程度で、オゾン濃度を濃くすると、反応速度が速くなる、発泡が少なくなる等の利点がある。ここでのオゾン利用効率は９０％以上であるが、若干の排オゾン１４が発生するので、これは別途排オゾン処理装置で処理される。また、こうした処理では同時に水中の色度成分もオゾン酸化により除去されるので、色度が低く透明感が高くＣＯＤも除去されたオゾン処理水１５が得られることになる。
【００２５】
次に、更なる別の処理法の参考例を図面を参照して説明する。図３は下水処理を目的とした更なる別の処理法の参考例を示すフロー図である。図３の処理法は基本的には図１の処理法に類似しており、異なる点はＣＯＤの高い生物処理水を、光触媒存在下でオゾン処理している点にある。したがって、説明はその点に限定し、前段にあたる下水の活性汚泥処理系と汚泥のオゾン処理系の説明は省略する。
【００２６】
図３の処理法の特徴は前記処理系の後段に、水用オゾン処理槽１３に光触媒ペレット１９を投入し流動させつつ水銀灯１８の照明下でオゾン処理を行う点にあり、添加するオゾン９ｂはオゾン発生機８から得ている。処理機能を説明すると、最終沈殿池３を経た水は溶解性のＣＯＤが高い状態で水用オゾン処理槽１３に流入し、光触媒存在下でオゾン酸化処理される。光触媒としては二酸化チタン、酸化亜鉛、三酸化タングステン等が利用できるが、二酸化チタンが効率の点から望ましい。光触媒ペレット１９の大きさは直径３〜５ｍｍ程度であり、光触媒の粉末を重量比１〜１０％でポリエチレングリコールと混合し重合反応を進行させた後、塩化カルシウム溶液中に滴下形成して得たものである。このペレットの比重は１程度で、気液混合槽での流動は良好である。光触媒ペレット１９の投入量は５０〜３００ｋｇ／ｍ³ 程度である。光触媒は有機物をオゾン酸化した時に生成する中間体を光の照射条件下で効率良く分解する作用があるので、オゾンと光触媒との併用処理によって流入したＣＯＤ成分が除去されるのである。なお、光触媒ペレット１９が流出しないよう、通常は目幅１ｍｍ程度のウエッジワイヤスクリーンを水用オゾン処理槽１３の流出口に設けている。光エネルギーを与えるための光源としては通常の水銀灯が用いられ、光の照射量は１〜２０ｋＷ・秒／ｍ³ 程度である。
【００２７】
オゾン酸化反応を加速する目的で紫外線ランプを用いることもできる。実験結果によると、こうした場合のＣＯＤ除去率は４０％以上であり、オゾン添加量は５〜２０ｍｇ／Ｌ程度、処理時間は０．５〜４時間程度である。添加するオゾン濃度は２０〜２００ｇ／Ｎｍ³程度で、オゾン濃度を濃くすると、反応速度が速くなる、発泡が少なくなる等の利点がある。ここでのオゾン利用効率は９０％以上であるが、若干の排オゾン１４が発生するので、これは別途排オゾン処理装置で処理される。また、こうした処理では同時に水中の色度成分もオゾン酸化により除去されるので、色度が低く透明感が高くＣＯＤも除去されたオゾン処理水１５が得られる。なお、図３では水用オゾン処理槽１３の中に光触媒ペレット１９を投入した形態を示したが、オゾン処理槽と光触媒処理部を分離し、新たに光触媒処理槽を設けて、オゾン処理後に光触媒処理をおこなっても同様の効果が得られる。また、光触媒は板状の構造材に塗布し充填する、小片状の板に付着させて投入する等、前記と異なる方法で槽内に入れてもよい。
【００２８】
次に、本発明による第１の処理法の実施例を図面を参照して説明する。図４は下水処理を目的とした本発明の第１の処理法の実施例を示すフロー図である。この処理法は下水の活性汚泥処理系と汚泥のオゾン処理系からなる従来の処理法にオゾン処理と再度の生物処理を付加した点に特徴がある。したがって、説明はその点に限定し、前段にあたる下水の活性汚泥処理系と汚泥のオゾン処理系の説明は省略する。
【００２９】
本発明における第１の処理法では前記処理系から流出した水を水用オゾン処理槽１３でオゾン処理し、さらにここで得られたオゾン処理水１５を好気性ろ床２０において再度生物処理し処理水２５を得ている。フローの順に処理機能を説明すると、水用オゾン処理槽１３では通常のオゾン酸化処理が行われる。この場合のＣＯＤ除去率は２０〜３０％であり、オゾン添加量は５〜２０ｍｇ／Ｌ程度、処理時間は５〜２０分程度である。添加するオゾン濃度は２０〜２００ｇ／Ｎｍ³ 程度で、オゾン濃度を濃くすると、反応速度が速くなることや、発泡が少なくなること等の利点がある。オゾン９ｂはオゾン発生機８から得ている。ここでのオゾン利用効率は９０％以上であるが、若干の排オゾン１４が発生するので、これは別途排オゾン処理装置で処理される。次にオゾン処理水１５は好気性ろ床２０に流入し、生物処理を受ける。この理由は、オゾン処理のみではＣＯＤ除去率は２０〜３０％とあまり高くないが、オゾン酸化により微生物処理可能な中間体が生成しているので、その中間体を好気性ろ床２０において微生物の働きで除去することにより、ＣＯＤ除去率をさらに上げようとするためである。ここで好気性ろ床２０の構造及び処理機能について説明すると、この装置は生物処理とろ過処理を兼用しており、セラミック又はアンスラサイト等からなるろ材２１が充填され、ろ材２１の表面に生育した微生物の働きによって処理がなされる。処理条件として、ろ過速度は３０〜１００ｍ／日程度、空気は下部から処理水量の２〜５倍程度が供給される。オゾン処理水１５はここで生物処理を受け、ＣＯＤが除去された後、処理水貯留槽２２を経て処理水２５として放流される。ただし、生物処理を続けていると微生物が増殖し、次第にろ材２１が詰まってくるので余剰微生物を除去する操作が必要となる。これが、逆洗で、逆洗は空気と水の併用で行われ、水は処理水貯留槽２２内の処理水２５が使用され、逆洗ポンプ２３によって好気性ろ床２０下部から送り込まれる。逆洗時間は３０分程度で、頻度は数日に１度程度と少ない。逆洗水は汚泥を含むので、逆洗汚泥２４として再度生物反応槽２に返送される。この逆洗汚泥２４の量は生物反応槽２で増殖する活性汚泥の量よりはるかに少ないので、逆洗汚泥２４の投入によって下水の活性汚泥処理系と汚泥のオゾン処理系が影響を受けることはないのである。したがって、この第１の処理法においても、汚泥が全体として発生せず、しかも処理水２５ＣＯＤは低くなる。なお、後段の生物処理法として好気性ろ床法を述べたが、他の方法でも良く、例えば接触曝気法でも同様の効果が得られ、発生した汚泥は生物反応槽２に返送されるのは言うまでもない。
【００３０】
次に、本発明による第２の処理法の実施例を図面を参照して説明する。図５は下水処理を目的とした本発明の第２の処理法の実施例を示すフロー図である。第２の処理法は図１の処理法に再度の生物処理法として好気性ろ床法を付加している。図１の処理法でも処理水ＣＯＤの低減は可能であるが、第２の方法はより一層の低減を目的とした場合で、水用オゾン処理槽１３におけるオゾン酸化の結果として微生物処理可能な中間体が生成しているので、その中間体を好気性ろ床２０において微生物の働きで除去することにより、ＣＯＤ除去率をさらに上げることができる。後段のオゾン処理及び生物処理についてはすでに図１の処理法、第１の処理法で述べているので、説明を省略する。
【００３１】
次に、本発明による第３の処理法の実施例を図面を参照して説明する。図６は下水処理を目的とした本発明の第３の処理法の実施例を示すフロー図である。第３の処理法は図２の処理法に再度の生物処理法として好気性ろ床法を付加している。図２の処理法でも処理水ＣＯＤの低減は可能であるが、第３の方法はより一層の低減を目的とした場合で、水用オゾン処理槽１３におけるオゾン酸化の結果として微生物処理可能な中間体が生成しているので、その中間体を好気性ろ床２０において微生物の働きで除去することにより、ＣＯＤ除去率をさらに上げることができる。後段のオゾン処理及び生物処理についてはすでに図２の処理法、第１の処理法で述べているので、説明を省略する。
【００３２】
次に、本発明による第４の処理法の実施例を図面を参照して説明する。図７は下水処理を目的とした本発明の第４の処理法の実施例を示すフロー図である。第４の処理法は図３の処理法に再度の生物処理法として好気性ろ床法を付加している。図３の処理法でも処理水ＣＯＤの低減は可能であるが、第４の方法はより一層の低減を目的とした場合で、水用オゾン処理槽１３におけるオゾン酸化の結果として微生物処理可能な中間体が生成しているので、その中間体を好気性ろ床２０において微生物の働きで除去することにより、ＣＯＤ除去率をさらに上げることができる。後段のオゾン処理及び生物処理についてはすでに図３の処理法、第１の処理法で述べているので、説明を省略する。
【００３３】
以上、下水を例として実施例を述べたが、下水に限らず有機性の排水であればこれらの処理法を適用することができる。また、処理水ＣＯＤを除去することができる７種の処理法の実施例を説明しているが、このうちどの方法を選択するかは、対象とする排水の水質、目標処理水質、経済性、維持管理性等を考慮し、個々に決定すれば良い。
【００３４】
【発明の効果】
以上、本発明の処理方法を説明したが、本発明は特開平６−２０６０８８号公報に記載された処理法の問題点である、ＣＯＤの高い処理水の流出を解決したものである。
すなわち、本発明は特開平６−２０６０８８号公報に記載された処理法の後段で、オゾン処理、オゾン酸化促進処理、生物処理を行って処理水ＣＯＤを除去する方法である。
【００３５】
図１、図２及び図３の方法は、オゾン処理と紫外線処理、過酸化水素処理、光触媒処理を併用することによって、オゾン処理単独では得られない高い溶解性有機物の分解を達成しＣＯＤの除去を実現している。また、第１の方法では、オゾン処理の後で生物処理を行うことにより、生成した中間体を除去して高いＣＯＤの除去を実現し、さらに発生する少量の汚泥を前段の活性汚泥処理系に返送して処理することにより、系全体としての汚泥発生も抑制し、汚泥が出ないとする特開平６−２０６０８８号公報に記載された処理法の特徴を堅持している。
【００３６】
さらに、第２、第３及び第４の方法は、図１、図２及び図３の方法で得られた処理水をさらに生物処理することにより、より高いＣＯＤ除去を実現すすとともに、発生する少量の汚泥を前段の生物処理系に返送して処理することにより、系全体としての汚泥発生も抑制し、汚泥が出ないとする特開平６−２０６０８８号公報に記載された処理法の特徴を堅持している。
【００３７】
このように、本発明の処理法によれば、高いＣＯＤ除去を安定して実現することができる。
【図面の簡単な説明】
【図１】参考例のフロー図
【図２】別の参考例のフロー図
【図３】更なる別の参考例のフロー図
【図４】本発明の第１の実施例のフロー図
【図５】本発明の第２の実施例のフロー図
【図６】本発明の第３の実施例のフロー図
【図７】本発明の第４の実施例のフロー図
【符号の説明】
１下水
２生物反応槽
３最終沈殿池
４散気装置
５返送汚泥ポンプ
６返送汚泥
７引抜汚泥ポンプ
８オゾン発生機
９ａオゾン
９ｂオゾン
１０汚泥用オゾン処理槽
１１オゾン処理汚泥
１２紫外線ランプ
１３水用オゾン処理槽
１４排オゾン
１５オゾン処理水
１６過酸化水素水貯留槽
１７薬注ポンプ
１８水銀灯
１９光触媒ペレット
２０好気性ろ床
２１ろ材
２２処理水貯留槽
２３逆洗
２４逆洗汚泥
２５処理水
２６空気[0001]
[Industrial application fields]
The present invention relates to a method for treating organic wastewater by a combination of a biological method and a physicochemical method, and particularly relates to a treatment method for suppressing the generation of excess sludge.
[0002]
[Prior art]
When sewage, domestic wastewater, organic factory wastewater, etc. are treated by a biological method represented by the activated sludge method, surplus sludge is generated as microorganisms grow. As the treatment method of surplus sludge, dehydration and landfill are generally used, but surplus sludge is generated as much as possible due to the fact that the dehydrator is expensive and cumbersome to operate, and there is not enough land for landfill. There is a need for wastewater treatment methods that do not allow them to occur.
[0003]
As a method suitable for this requirement, Japanese Patent Application Laid-Open No. 6-206088 describes a wastewater treatment method that does not generate excess sludge by combining an ozone treatment method with a biological treatment method. In the method of this publication, in the method of aerobic treatment of organic drainage in the presence of activated sludge containing aerobic microorganisms, an amount of activated sludge larger than the amount of sludge that is proliferated by assimilation of BOD in the liquid to be treated. Is an aerobic treatment method for organic drainage, wherein the extracted sludge is treated with ozone and then introduced into the aerobic treatment system. In this method, a part of the activated sludge is treated with ozone to destroy the cell walls of the microorganisms, convert the microorganisms into biodegradable organic substances, and perform the treatment again. Therefore, the decomposition of the organic substances is promoted and no sludge is generated. It will be. It is an excellent idea that combines the features of biological treatment and ozone treatment.
[0004]
[Problems to be solved by the invention]
However, in the treatment method described in Japanese Patent Application Laid-Open No. 6-206088, a soluble organic substance that is difficult to be decomposed by microorganisms gradually accumulates in the reaction tank, and a part thereof is contained in the treated water and flows out. There is a problem that the soluble COD and TOC in water increase. For example, when sewage is treated by this method, the soluble COD in the treated water becomes about twice the COD of normal activated sludge process treated water. Discharging such high COD treated water was a big problem from the viewpoint of environmental protection.
[0005]
This invention is made | formed in view of the above-mentioned point, The objective is in the process which combined the biological treatment and the ozone treatment, and provides the processing method with which the excess sludge does not generate | occur | produce and the treated water COD is low. is there.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have established activated sludge as an activated sludge treatment system (in the present invention, a case where the preceding treatment system has conditions other than aerobic conditions such as anaerobic conditions is also established. The term “aerobic treatment system” is referred to as “activated sludge treatment system”, and the treatment method of introducing this extracted sludge to the activated sludge treatment system after ozone treatment is conducted. Since the COD component contained in the treated water is difficult to be decomposed by microorganisms, it must be decomposed by the strong oxidizing action of ozone, and in order to increase the treatment effect, the conditions under which the oxidizing action of ozone is promoted It was concluded that ozone oxidation is necessary. In addition, depending on the water quality, biodegradable soluble organic matter may be produced by ozone oxidation under conditions that promote the oxidation of ozone. The conclusion has been reached.
[0011]
In order to solve the above problems based on these findings, the following four types of specific processing methods are provided. Hereinafter, these processing methods will be described sequentially. In the first treatment method of the present invention, the activated sludge is extracted from an activated sludge treatment system mainly composed of a biological reaction tank and a final sedimentation basin, and the extracted sludge is treated with ozone and then introduced into the activated sludge treatment system. This is a treatment method in which the treated water having a high soluble COD from the activated sludge treatment system is subjected to ozone treatment, the water is further biologically treated, and the sludge generated from the biological treatment apparatus in the subsequent stage is returned to the biological reaction tank.
[0012]
In this treatment method, a biologically difficult-to-decompose soluble organic substance contained in the treated water by ozone treatment is oxidatively decomposed, and then an intermediate produced by ozone oxidation is removed by biological treatment to reduce the COD concentration. Moreover, the sludge generated from the biological treatment apparatus in the subsequent stage is returned to the biological reaction tank and processed, thereby suppressing the generation of sludge as a whole system.
[0013]
The second treatment method of the present invention is a process in which activated sludge is extracted from an activated sludge treatment system mainly composed of a biological reaction tank and a final sedimentation basin, and the extracted sludge is treated with ozone and then introduced into the activated sludge treatment system. Treated water with high solubility COD from the activated sludge treatment system is treated with ultraviolet irradiation and ozone treatment, and the water is further biologically treated, and the sludge generated from the biological treatment apparatus at the subsequent stage is returned to the biological reaction tank. It is a processing method to do.
[0014]
In this treatment method, ultraviolet rays act on ozone to promote the generation of OH radicals that have a strong oxidizing action. Therefore, if combined treatment with ultraviolet irradiation and ozone treatment is performed, the treatment is performed with strong oxidizing power. Biologically difficult-to-decompose soluble organic substances contained in water are oxidatively decomposed and the COD concentration is greatly reduced, and then the intermediate produced by the combined treatment is removed by biological treatment to reduce the COD concentration. To do. Moreover, the sludge generated from the biological treatment apparatus in the subsequent stage is returned to the biological reaction tank and processed, thereby suppressing the generation of sludge as a whole system.
[0015]
In the third treatment method of the present invention, the activated sludge is extracted from an activated sludge treatment system mainly composed of a biological reaction tank and a final sedimentation basin, and the extracted sludge is treated with ozone and then introduced into the activated sludge treatment system. Ozone treatment is performed while adding hydrogen peroxide to treated water having a high solubility COD from the activated sludge treatment system, and the water is further biologically treated, and sludge generated from a biological treatment apparatus in the subsequent stage is treated with the biological reaction tank. It is a processing method to return to.
[0016]
In this treatment method, hydrogen peroxide acts on ozone and promotes the generation of OH radicals that have a strong oxidizing action. Therefore, if combined treatment with hydrogen peroxide water and ozone treatment is performed , strong oxidizing power is achieved. In this way, the biologically difficult-to-decompose soluble organic matter contained in the treated water is oxidatively decomposed to significantly reduce the COD concentration, and then the intermediate produced by the combined treatment is removed by biological treatment. Reduce COD concentration. Moreover, the sludge generated from the biological treatment apparatus in the subsequent stage is returned to the biological reaction tank and processed, thereby suppressing the generation of sludge as a whole system.
[0017]
In the fourth treatment method of the present invention, the activated sludge is extracted from an activated sludge treatment system mainly composed of a biological reaction tank and a final sedimentation basin, and the extracted sludge is treated with ozone and then introduced into the activated sludge treatment system. Treated treated water with high soluble COD from the activated sludge treatment system is treated with ozone treatment and insoluble photocatalyst treatment, and the water is further biologically treated, and the sludge generated from the biological treatment apparatus in the subsequent stage is treated with the biological reaction tank. It is a processing method to return to.
[0018]
In this treatment method, the photocatalyst has an effect of efficiently decomposing an intermediate produced when the organic substance is oxidized with ozone under light irradiation conditions. Therefore, if the treatment with ozone treatment and the insoluble photocatalyst treatment is performed, the above treatment is performed. A treatment that removes the biodegradable soluble organic substances contained in water through the oxidative decomposition of ozone, the generation of some intermediates, and the decomposition of the intermediates by the photocatalyst, greatly reducing the COD concentration. Then, the intermediate remaining in the combined treatment is removed by biological treatment to reduce the COD concentration. Moreover, the sludge generated from the biological treatment apparatus in the subsequent stage is returned to the biological reaction tank and processed, thereby suppressing the generation of sludge as a whole system.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of processing according to the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing a reference example of a treatment method for sewage treatment. In FIG. 1, this treatment method is an activated sludge treatment system for sewage 1 comprising a biological reaction tank 2 and a final sedimentation basin 3, an ozone treatment of sludge comprising a drawn sludge pump 7, a sludge ozone treatment tank 10, and an ozone generator 8. The system is further composed of three systems, namely, a water ozone treatment system including a water ozone treatment tank 13 and an ultraviolet lamp 12. Of these, the activated sludge treatment system for sewage and the ozone treatment system for sludge have a form in which the treatment method described in JP-A-6-206088 is applied to sewage treatment.
[0020]
This prior art portion will be briefly described. The sewage 1 is treated with activated sludge while being supplied with air from the air diffuser 4 in the biological reaction tank 2, and solid-liquid separation is performed in the final sedimentation basin 3. The sludge is returned to the biological reaction tank 2 as the return sludge 6 via the return sludge pump 5, but a part of the sludge is sent to the sludge ozone treatment tank 10 via the extraction sludge pump 7, where it is subjected to ozone treatment. After that, it is introduced into the biological reaction tank 2. The amount of ozone 9a added is about 10 to 20 mg / L based on the inflow sewage amount. In the ozone treatment tank 10 for sludge, the cell walls of microorganisms constituting the activated sludge are destroyed, and the ozone treatment sludge 11 is introduced into the biological reaction tank 2 as an organic substance that can be treated with microorganisms, and most of it is decomposed into water and carbon dioxide gas. . Therefore, no sludge is generated from the prior art portion comprising this activated sludge treatment system and sludge ozone treatment system.
[0021]
The feature of the treatment method of FIG. 1 is that a water ozone treatment tank 13 equipped with an ultraviolet lamp 12 is provided at the latter stage of the treatment system, and the ozone 9b to be added is obtained from the ozone generator 8. Explaining the treatment function, the water that has passed through the final sedimentation basin 3 flows into the water ozone treatment tank 13 in a state where the soluble COD is high, and is subjected to ozone oxidation treatment while being irradiated with ultraviolet rays from the ultraviolet lamp 12. Although the amount of UV irradiation depends on the water quality, it is about 100 to 500 W · sec / m ³ . Since ultraviolet rays act on ozone to promote the generation of OH radicals having a strong oxidizing action, the COD component that has flowed into the tank is removed by strong oxidation. According to the experimental results, the COD removal rate is 40% or more under the conditions described above, the ozone addition amount is about 5 to 20 mg / L, and the treatment time is about 10 to 60 minutes. The ozone concentration to be added is about 20 to 200 g / Nm ^{3. When} the ozone concentration is increased, there are advantages such that the reaction rate is increased and foaming is reduced. Here, the ozone utilization efficiency is 90% or more, but a slight amount of exhausted ozone 14 is generated, which is separately treated by an exhausted ozone treatment device. Further, in such treatment, the chromaticity component in the water is also removed by ozone oxidation, so that the ozone treated water 15 having low chromaticity, high transparency, and COD removal can be obtained.
[0022]
In addition, although the form which immersed the ultraviolet lamp 12 in the ozone treatment tank 13 for water was shown in FIG. 1, the ozone treatment tank and the ultraviolet lamp irradiation part were isolate | separated, and the dissolved ozone remains after ozone addition. The same effect can be obtained by the method of irradiating with ultraviolet rays. In this case, the water to be treated may be circulated between the ozone treatment tank and the ultraviolet lamp irradiation unit. In addition, the biological reaction tank 2 has been described as an aerobic treatment so far, but the present embodiment is also established when an aerobic and anaerobic treatment is performed by intermittent aeration. This condition is the same in the processing methods shown in FIGS.
[0023]
Next, a reference example of another processing method will be described with reference to the drawings. FIG. 2 is a flowchart showing a reference example of another treatment method for sewage treatment. The treatment method of FIG. 2 is basically similar to the treatment method of FIG. 1, and the difference is that biological treatment water having a high COD is subjected to ozone treatment while adding hydrogen peroxide solution. Therefore, the description is limited to that point, and the description of the activated sludge treatment system for sewage and the ozone treatment system for sludge are omitted.
[0024]
The characteristic of the treatment method of FIG. 2 is that ozone treatment is performed in the water ozone treatment tank 13 while injecting the hydrogen peroxide solution stored in the hydrogen peroxide solution storage tank 16 using the chemical injection pump 17 at the latter stage of the treatment system. The ozone 9b to be added is obtained from the ozone generator 8. Explaining the treatment function, the water that has passed through the final sedimentation basin 3 flows into the water ozone treatment tank 13 with a high soluble COD, and is subjected to ozone oxidation treatment in the presence of hydrogen peroxide. Although the amount of hydrogen peroxide added depends on the water quality, it is about 10 to 30 mg / L. Since hydrogen peroxide acts on ozone and promotes the generation of OH radicals having a strong oxidizing action, the COD component that has flowed into the tank is removed by being strongly oxidized. The COD removal rate is 40% or more, the ozone addition amount is about 5 to 50 mg / L, and the treatment time is about 5 to 30 minutes. The ozone concentration to be added is about 20 to 200 g / Nm ^{3. When} the ozone concentration is increased, there are advantages such that the reaction rate is increased and foaming is reduced. Here, the ozone utilization efficiency is 90% or more, but a slight amount of exhaust ozone 14 is generated, which is separately processed by an exhaust ozone treatment device. In addition, such treatment simultaneously removes the chromaticity component in the water by ozone oxidation, so that the ozone-treated water 15 having low chromaticity, high transparency, and COD removal can be obtained.
[0025]
Next, a reference example of still another processing method will be described with reference to the drawings. FIG. 3 is a flowchart showing a reference example of still another treatment method for the purpose of sewage treatment. The treatment method of FIG. 3 is basically similar to the treatment method of FIG. 1, and the difference is that biological treatment water having a high COD is subjected to ozone treatment in the presence of a photocatalyst. Therefore, the description is limited to that point, and the description of the activated sludge treatment system for sewage and the ozone treatment system for sludge are omitted.
[0026]
The feature of the treatment method of FIG. 3 is that the ozone treatment is performed under the illumination of the mercury lamp 18 while the photocatalyst pellets 19 are introduced into the water ozone treatment tank 13 and flowed in the latter stage of the treatment system. Obtained from the ozone generator 8. Explaining the treatment function, the water that has passed through the final sedimentation basin 3 flows into the water ozone treatment tank 13 with a high soluble COD, and is subjected to ozone oxidation treatment in the presence of a photocatalyst. As the photocatalyst, titanium dioxide, zinc oxide, tungsten trioxide and the like can be used, but titanium dioxide is desirable from the viewpoint of efficiency. The size of the photocatalyst pellet 19 is about 3 to 5 mm in diameter. The photocatalyst powder was mixed with polyethylene glycol at a weight ratio of 1 to 10% to advance the polymerization reaction, and then dropped into a calcium chloride solution. Is. The specific gravity of the pellet is about 1, and the flow in the gas-liquid mixing tank is good. The input amount of the photocatalyst pellet 19 is about 50 to 300 kg / m ³ . Since the photocatalyst has an effect of efficiently decomposing an intermediate produced when the organic substance is oxidized with ozone under light irradiation conditions, the COD component flowing in is removed by the combined treatment of ozone and the photocatalyst. In order to prevent the photocatalyst pellet 19 from flowing out, a wedge wire screen having a mesh width of about 1 mm is usually provided at the outlet of the water ozone treatment tank 13. A normal mercury lamp is used as a light source for providing light energy, and the amount of light irradiation is about 1 to 20 kW · second / m ³ .
[0027]
An ultraviolet lamp can also be used for the purpose of accelerating the ozone oxidation reaction. According to the experimental results, the COD removal rate in this case is 40% or more, the ozone addition amount is about 5 to 20 mg / L, and the treatment time is about 0.5 to 4 hours. The ozone concentration to be added is about 20 to 200 g / Nm ^{3. When} the ozone concentration is increased, there are advantages such that the reaction rate is increased and foaming is reduced. Here, the ozone utilization efficiency is 90% or more, but a slight amount of exhaust ozone 14 is generated, which is separately processed by an exhaust ozone treatment device. Further, in such treatment, the chromaticity component in the water is also removed by ozone oxidation, so that the ozone treated water 15 having low chromaticity, high transparency, and COD removal can be obtained. Although FIG. 3 shows a mode in which the photocatalyst pellets 19 are introduced into the water ozone treatment tank 13, the ozone treatment tank and the photocatalyst treatment section are separated, and a new photocatalyst treatment tank is provided. The same effect can be obtained even if processing is performed. Further, the photocatalyst may be put in the tank by a method different from the above, for example, applied to a plate-shaped structural material and filled, or attached to a small piece-like plate.
[0028]
Next, an embodiment of the first treatment method according to the present invention will be described with reference to the drawings. FIG. 4 is a flowchart showing an embodiment of the first treatment method of the present invention for the purpose of sewage treatment. This treatment method is characterized in that ozone treatment and biological treatment again are added to the conventional treatment method comprising an activated sludge treatment system for sewage and an ozone treatment system for sludge. Therefore, the description is limited to that point, and the description of the activated sludge treatment system for sewage and the ozone treatment system for sludge are omitted.
[0029]
In the first treatment method of the present invention, water that has flowed out of the treatment system is ozone treated in the water ozone treatment tank 13, and the ozone treated water 15 obtained here is biologically treated again in the aerobic filter bed 20. Water 25 is obtained. The processing functions will be described in the order of the flow. In the ozone treatment tank for water 13, normal ozone oxidation treatment is performed. In this case, the COD removal rate is 20 to 30%, the amount of ozone added is about 5 to 20 mg / L, and the treatment time is about 5 to 20 minutes. The ozone concentration to be added is about 20 to 200 g / Nm ^{3. When} the ozone concentration is increased, there are advantages such as a higher reaction rate and less foaming. The ozone 9b is obtained from the ozone generator 8. Here, the ozone utilization efficiency is 90% or more, but a slight amount of exhaust ozone 14 is generated, which is separately processed by an exhaust ozone treatment device. Next, the ozone-treated water 15 flows into the aerobic filter bed 20 and undergoes biological treatment. This is because the ozone treatment alone does not give a high COD removal rate of 20 to 30%, but an intermediate that can be treated by microorganisms is produced by ozone oxidation. This is to further increase the COD removal rate by removing it by working. Here, the structure and the processing function of the aerobic filter bed 20 will be described. This apparatus combines biological treatment and filtration treatment, and is filled with a filter medium 21 made of ceramic or anthracite and grows on the surface of the filter medium 21. Processing is performed by the action of microorganisms. As processing conditions, the filtration rate is about 30 to 100 m / day, and about 2 to 5 times the amount of treated water is supplied from the bottom. The ozone-treated water 15 is subjected to biological treatment here, and after COD is removed, it is discharged as treated water 25 through the treated water storage tank 22. However, if the biological treatment is continued, the microorganisms grow and the filter medium 21 is gradually clogged. Therefore, an operation for removing excess microorganisms is required. This is backwashing, and the backwashing is performed by using air and water together. The treated water 25 in the treated water storage tank 22 is used as the water, and is fed from the lower part of the aerobic filter bed 20 by the backwash pump 23. The backwash time is about 30 minutes and the frequency is as low as about once every few days. Since the backwash water contains sludge, it is returned again to the biological reaction tank 2 as the backwash sludge 24. Since the amount of this backwashed sludge 24 is much smaller than the amount of activated sludge that grows in the biological reaction tank 2, the introduction of the backwashed sludge 24 will affect the activated sludge treatment system of sewage and the ozone treatment system of sludge. There is no. Therefore, even in the first treatment method, sludge is not generated as a whole, and the treated water 25COD is low. In addition, although the aerobic filter bed method was described as the biological treatment method at the latter stage, other methods may be used, for example, the same effect can be obtained by the contact aeration method, and the generated sludge is returned to the biological reaction tank 2. Needless to say.
[0030]
Next, an example of the second processing method according to the present invention will be described with reference to the drawings. FIG. 5 is a flowchart showing an embodiment of the second treatment method of the present invention for the purpose of sewage treatment. In the second treatment method, an aerobic filter bed method is added to the treatment method of FIG. 1 as a biological treatment method again. The treatment method of FIG. 1 can also reduce the treated water COD, but the second method is for the purpose of further reduction, and is an intermediate that can treat microorganisms as a result of ozone oxidation in the water ozone treatment tank 13. Since the body is produced, the COD removal rate can be further increased by removing the intermediate in the aerobic filter bed 20 by the action of microorganisms. The subsequent ozone treatment and biological treatment have already been described in the treatment method and the first treatment method of FIG.
[0031]
Next, an example of the third treatment method according to the present invention will be described with reference to the drawings. FIG. 6 is a flowchart showing an embodiment of the third treatment method of the present invention for the purpose of sewage treatment. In the third treatment method, an aerobic filter bed method is added to the treatment method of FIG. 2 as a biological treatment method again. The treatment method of FIG. 2 can reduce the treated water COD, but the third method is for the purpose of further reduction, and an intermediate in which microorganisms can be treated as a result of ozone oxidation in the water ozone treatment tank 13. Since the body is produced, the COD removal rate can be further increased by removing the intermediate in the aerobic filter bed 20 by the action of microorganisms. The subsequent ozone treatment and biological treatment have already been described in the treatment method and the first treatment method of FIG.
[0032]
Next, an example of the fourth treatment method according to the present invention will be described with reference to the drawings. FIG. 7 is a flowchart showing an embodiment of the fourth treatment method of the present invention for the purpose of sewage treatment. In the fourth treatment method, an aerobic filter bed method is added as a biological treatment method to the treatment method of FIG. The treatment method of FIG. 3 can also reduce the treated water COD, but the fourth method is for the purpose of further reduction, and an intermediate in which microorganisms can be treated as a result of ozone oxidation in the water ozone treatment tank 13. Since the body is produced, the COD removal rate can be further increased by removing the intermediate in the aerobic filter bed 20 by the action of microorganisms. The subsequent ozone treatment and biological treatment have already been described in the treatment method and the first treatment method of FIG.
[0033]
As mentioned above, although the Example was described by taking sewage as an example, these treatment methods can be applied not only to sewage but to organic wastewater. Moreover, although the example of the 7 types of processing methods which can remove treated water COD is demonstrated, which method is chosen among these is the water quality of the target wastewater, target treated water quality, economical efficiency, It may be determined individually considering maintenance and management.
[0034]
【The invention's effect】
Although the treatment method of the present invention has been described above, the present invention solves the outflow of treated water having a high COD, which is a problem of the treatment method described in JP-A-6-206088.
That is, the present invention is a method for removing treated water COD by performing ozone treatment, ozone oxidation promotion treatment, and biological treatment at the latter stage of the treatment method described in JP-A-6-206088.
[0035]
The method of FIGS. 1, 2, and 3 achieves the decomposition of highly soluble organic matter that cannot be obtained by ozone treatment alone by using ozone treatment, ultraviolet treatment, hydrogen peroxide treatment, and photocatalyst treatment together, and removes COD. Is realized. In the first method, biological treatment is performed after the ozone treatment to remove the generated intermediate and achieve high COD removal. Further, a small amount of generated sludge is added to the activated sludge treatment system in the previous stage. By returning and processing, the sludge generation | occurrence | production of the whole system is also suppressed and the characteristic of the processing method described in Unexamined-Japanese-Patent No. 6-206088 which sticks out sludge is maintained.
[0036]
Furthermore, the second, third and fourth methods achieve higher COD removal by further biological treatment of the treated water obtained by the methods of FIGS. 1, 2 and 3, and the small amount generated. The sludge generated in this system is treated by returning it to the biological treatment system in the previous stage, thereby suppressing the generation of sludge as a whole system and maintaining the characteristics of the treatment method described in JP-A-6-206088. is doing.
[0037]
Thus, according to the treatment method of the present invention, high COD removal can be stably realized.
[Brief description of the drawings]
FIG. 1 is a flowchart of a reference example. FIG. 2 is a flowchart of another reference example. FIG. 3 is a flowchart of another reference example. FIG. 4 is a flowchart of the first embodiment of the present invention. 5 is a flow diagram of a fourth embodiment of the second embodiment the flow diagram of Figure 6 a third embodiment the flow diagram FIG 7 the invention of the present invention of the present invention description of Reference numerals]
DESCRIPTION OF SYMBOLS 1 Sewage 2 Biological reaction tank 3 Final sedimentation tank 4 Aeration apparatus 5 Return sludge pump 6 Return sludge 7 Extraction sludge pump 8 Ozone generator 9a Ozone 9b Ozone 10 Sludge ozone treatment tank 11 Ozone treatment sludge 12 UV lamp 13 Water ozone Treatment tank 14 Waste ozone 15 Ozone treated water 16 Hydrogen peroxide solution storage tank 17 Chemical pump 18 Mercury lamp 19 Photocatalyst pellet 20 Aerobic filter bed 21 Filter medium 22 Treated water storage tank 23 Backwash 24 Backwash sludge 25 Treated water 26 Air

Claims

An activated sludge process that treats organic wastewater, with the amount of activated sludge that is larger than the amount of sludge proliferated by microbial treatment of the treated wastewater being extracted from the activated sludge treatment system, and the extracted sludge is treated with ozone and then activated sludge treatment system In the treatment to be introduced into the system, ozone treatment of the treated water from the activated sludge treatment system is performed at a later stage, the water is further biologically treated, and the sludge generated from the biological treatment apparatus is returned to the activated sludge treatment system. An activated sludge process water treatment method characterized by the above.

An activated sludge process that treats organic wastewater, with the amount of activated sludge that is larger than the amount of sludge proliferated by microbial treatment of the treated wastewater being extracted from the activated sludge treatment system, and the extracted sludge is treated with ozone and then activated sludge treatment system In the treatment to be introduced into the activated sludge, the treated water from the activated sludge treatment system is treated in combination with ultraviolet irradiation and ozone treatment, and the water is further biologically treated, and the sludge generated from this biological treatment device is activated. An activated sludge process water treatment method characterized by being returned to a sludge treatment system.

An activated sludge process that treats organic wastewater, with the amount of activated sludge that is larger than the amount of sludge proliferated by microbial treatment of the treated wastewater being extracted from the activated sludge treatment system, and the extracted sludge is treated with ozone and then activated sludge treatment system In the treatment to be introduced, the ozone treatment is performed while adding hydrogen peroxide water to the treated water from the activated sludge treatment system in the subsequent stage, and the water is further biologically treated, and the sludge generated from the biological treatment device is treated with the above-mentioned sludge. An activated sludge process water treatment method characterized by returning to an activated sludge treatment system.

An activated sludge process that treats organic wastewater, with the amount of activated sludge that is larger than the amount of sludge proliferated by microbial treatment of the treated wastewater being extracted from the activated sludge treatment system, and the extracted sludge is treated with ozone and then activated sludge treatment system In the treatment to be introduced into the wastewater, the treated water from the activated sludge treatment system is treated at the subsequent stage in combination with ozone treatment and insoluble photocatalyst treatment, and the water is further biologically treated, and the sludge generated from the biological treatment device is treated. An activated sludge process water treatment method comprising returning to the activated sludge treatment system.