JP4594508B2

JP4594508B2 - Organic wastewater treatment method and treatment apparatus

Info

Publication number: JP4594508B2
Application number: JP2000308505A
Authority: JP
Inventors: 龍男中谷; 一栄高岡; 鐐三入江
Original assignee: Mitsui Engineering and Shipbuilding Co Ltd; Mitsui E&S Holdings Co Ltd
Current assignee: Mitsui Engineering and Shipbuilding Co Ltd; Mitsui E&S Co Ltd
Priority date: 2000-10-06
Filing date: 2000-10-06
Publication date: 2010-12-08
Anticipated expiration: 2020-10-06
Also published as: JP2002113486A

Description

【０００１】
【発明の属する技術分野】
本発明は、下水等の有機性廃水の処理方法及び処理装置に関し、詳しくは生物処理の結果多量に発生する生物汚泥量を著しく減少させることができると共に活性汚泥の凝集沈降性、脱水性を向上させて活性汚泥処理設備の操作性の改善、経済性の向上に寄与する有機性廃水の処理方法及び処理装置に関する。
【０００２】
【従来の技術】
下水等の有機性廃水の処理は、一般的に、活性汚泥法を始めとする生物処理法によって行われる。生物処理法では、汚水中の有機物は生物によって異化、同化され、水中より除去されることになる。
【０００３】
しかし、同化された有機物は汚泥中に蓄積される。即ち、汚泥量が増大し、この汚泥の処分が処理費用の増大を招く結果となっている。このような問題に対応するために発生汚泥量を減少させる方法が数多く提案されている。
【０００４】
生物処理方式により発生汚泥量を減少させる方法としては、長時間曝気法や生物膜法がある。これらの方法は有機物負荷や滞留時間等の運転変数を制御して発生汚泥量を抑制する方式である。
【０００５】
一方、活性汚泥中の微生物細胞を破壊し、可溶化した後、処理槽内で生物処理し、無機化することによって発生汚泥量を低下させる方法が提案されている。可溶化技術としては、熱処理、酸アルカリ処理、化学的酸化処理、機械的粉砕処理、酵素処理、微生物処理等多くの方法が提案されている。たとえば返送汚泥の一部をオゾン酸化し、可溶化した後、処理槽に返送することによって余剰汚泥量を著しく減少させる方法が特開平８−１０３７８６号公報に開示されている。また同様に、高温で可溶化処理する方法が特開平９−１０７９１号公報に開示されている。
【０００６】
また汚泥の凝集沈降性は自然沈降によって汚泥と処理水に分離する活性汚泥法においては、運転管理上最も重要な因子であり、運転管理者はこの凝集沈降性の維持に多大な労苦を要しているのが現状である。一旦、凝集沈降性が悪化した場合は、処理水質の緊急な回復をはかるために薬剤の投入が試みられこともある。さらに余剰汚泥として排出される汚泥は、脱水処理を経て、焼却、コンポスト化等の後処理工程へ送られるが、脱水処理に際しては、所定の含水率を達成するために高価な薬剤が用いられているのが実状である。
【０００７】
【発明が解決しようとする課題】
しかし、生物処理方式により発生汚泥量を減少させる方法は、汚泥減少量が小さく、処理槽あたりの有機物処理量を少なくすることが通常であるため、処理効率が悪くなる。
【０００８】
また汚泥の可溶化処理工程を採用する場合は、汚泥の主体である微生物細胞を破壊する必要がある。この破壊のために前記した方法（特開平８−１０３７８６号公報や特開平９−１０７９１号公報に記載の方法）が利用されるが、微生物細胞を覆う細胞壁はかなり強固であり、穏和な処理条件であれば細胞壁の破壊が起きず、可溶化処理が不十分となる問題がある。
【０００９】
一方、可溶化処理の効果を充足させるためには、多量のエネルギーを要し、経済的に不利となる問題が発生する。
【００１０】
また汚泥と処理水の固液分離を自然沈降方式で行う方法では、絶えず汚泥の凝集沈降性に配慮した運転管理と薬剤使用による運転費増大の問題が発生する。更に汚泥の脱水性が悪ければ脱水工程での薬剤使用が必須となり、経済性の悪化をもたらす。
【００１１】
そこで、本発明の課題は、上記従来の諸問題を解決し、効果的に発生汚泥量を減少させると共に固液分離工程における正常な固液分離を容易ならしめ、また余剰汚泥の脱水性を向上させる有機性廃水の処理方法及び処理装置を提供することにある。
【００１２】
また本発明の他の課題は、以下の記載によって明らかとなるであろう。
【００１３】
【課題を解決するための手段】
有機性廃水の生物処理は活性汚泥中の多様な微生物間の相互作用によって行われていることは周知のことであり、微生物の中でも細菌の働きは重要なものと考えられる。ただし、活性汚泥中には多様な細菌の生息が確認されているものの、全てが明らかになっているわけではなく、個々の細菌の機能を積極的に活用し制御して廃水処理に適用している例は窒素除去等の一部に限られている。このような状況下で、内生胞子形成細菌の中でもバチルス属細菌は、その産出する酵素の有機物分解能力の高さから有機性廃水処理に極めて有用な細菌であると考えられている。
【００１４】
しかし、バチルス属細菌は活性汚泥中に含まれ一般的な細菌であるとの認識があるものの、その生態を十分に解明し、制御し、機能を活用している事例は存在しない。
【００１５】
このような点に鑑み、内生胞子形成細菌、特にバチルス属細菌の生態を解明し、制御し、活性汚泥中で十分に機能を発揮させる技術として、本発明者らは先に特願２０００−１０２５３３号（以下、先提案の技術という）を提案した。
【００１６】
即ち、バチルス属細菌に代表される内生胞子形成細菌は、その生存する環境によって栄養細胞から胞子、胞子から栄養細胞へと変遷し、細胞の変遷課程で、グルコサミダーゼ、リゾチーム、アミダーゼ、エンドペプチダーゼなどの細胞壁溶解酵素を産出する。更にバチルス属細菌は栄養細胞から胞子への段階では菌体外酵素としてα−アミラーゼ、プロテアーゼを産出する。これらの酵素の持つ作用効果を活用すれば、廃水中の有機物を効果的に分解すると共に汚泥の構成物である微生物の一部は溶解され、他の生存する微生物によって資化され、無機化されて発生汚泥量を著しく減少させることが可能となる。また汚泥に含まれた親水性の高い有機物を分解することによって、汚泥の膨潤化を防ぎ、汚泥の凝集沈降性の悪化を防止することが可能となる。
【００１７】
先提案の技術は、これらの機能を発現するために、内生胞子形成細菌の胞子をアミノ酸、ペプチド、糖質などの発芽促進物質存在下で、栄養細胞に転換する過程と、内生胞子形成細菌の栄養細胞を資化できる栄養物質が減少した環境下で、胞子の状態に転換する過程を水処理工程に組み込んだものである。
【００１８】
本発明者らは、先提案の技術を更に改良し、汚泥のより一層の脱水性向上、及び経済性の向上のために、内生胞子形成細菌の機能活用をはかる具体的手段を見いだし、本発明に至ったものである。
【００１９】
即ち、上記課題を解決する本発明は以下の構成を有するものである。
（請求項１）処理系の前段に処理槽を有し、且つ後段に固液分離手段を有し、該処理系に有機性廃水を導入して好気性生物処理する有機性廃水の処理方法において、固液分離手段より引き抜かれた内生胞子形成細菌の胞子を含む汚泥を、前記処理槽の前段に位置し、汚泥中の非生物性の残存有機物の資化と、消滅及び胞子形成細菌の胞子の活性汚泥フロックからの遊離を行う汚泥改質槽に導いた後前記処理槽に導く際に、汚泥改質槽には、有機性廃水を導入することなく、かつ該有機性廃水は前記処理槽に導入され、汚泥改質槽に導く汚泥量は処理系に導入される有機性廃水量の２．５〜５倍量とし、更に前記処理槽に供給される有機性廃水によって汚泥中の内生胞子形成細菌の胞子を発芽させて栄養細胞に転換し、ケイ素とマグネシウムを含む単一又は複合の化合物を加えて該栄養細胞を増殖させながら有機性廃水を処理することを特徴とする有機性廃水の処理方法。
【００２０】
（請求項２）汚泥改質槽の溶存酸素濃度が、０．１〜１．０ppmの範囲であり、処理槽の溶存酸素濃度が、０．２〜２ppmの範囲であることを特徴とする請求項１記載の有機性廃水の処理方法。
【００２１】
（請求項３）処理槽が、空気供給手段を有する曝気槽からなり、該曝気槽は、２段以上の多段の槽からなり、後段の槽から第１段の槽に汚泥を返送することを特徴とする請求項１又は２記載の有機性廃水の処理方法。
【００２２】
（請求項４）処理槽に、内生胞子形成細菌の胞子発芽促進物質を添加することを特徴とする請求項１、２又は３記載の有機性廃水の処理方法。
【００２３】
（請求項５）内生胞子形成細菌の胞子発芽促進物質が、アミノ酸、ポリペプチド又は糖質のうちの少なくとも１種であることを特徴とする請求項４記載の有機性廃水の処理方法。
【００２４】
（請求項６）アミノ酸が、Ｌ−アラニン、Ｌ−アスパラギン、Ｌ−イソロイシン、Ｌ−チロシン、ＤＬ−バリン、ＤＬ−アスパラギン酸又はカサアミノ酸から選ばれる少なくとも１種であることを特徴とする請求項５記載の有機性廃水の処理方法。
【００２５】
（請求項７）糖質が、Ｄ−グルコース、ガラクトース、フルクトース、マンノース、マルトース、多糖類、オリゴ糖又は糖類の加水分解物から選ばれる少なくとも１種であることを特徴とする請求項５記載の有機性廃水の処理方法。
【００２６】
（請求項８）内生胞子形成細菌が、バチルス属細菌であることを特徴とする請求項１〜７の何れかに記載の有機性廃水の処理方法。
【００２７】
（請求項９）処理系の前段に処理槽を有し、且つ後段に固液分離手段を有し、該処理系に有機性廃水を導入して好気性生物処理する有機性廃水の処理装置において、前記処理槽の前段に、有機性廃水は導入することなく、固液分離手段から引き抜いた汚泥を導いて、汚泥中の非生物性の残存有機物の資化と、消滅及び胞子形成細菌の胞子の活性汚泥フロックからの遊離を行う汚泥改質槽を有し、固液分離手段より内生胞子形成細菌の胞子を含む汚泥を引き抜く手段と、該引き抜き手段によって引き抜かれた汚泥を前記処理槽の前段に位置する汚泥改質槽に導く手段と、該汚泥改質槽から前記処理槽に導く手段と、前記汚泥改質槽に導く汚泥量を処理系に導入される有機性廃水量の２．５〜５倍量に調整する手段とを有し、更に前記処理槽に供給される有機性廃水によって汚泥中の内生胞子形成細菌の胞子を発芽させて栄養細胞に転換する構成と、ケイ素とマグネシウムを含む単一又は複合の化合物を加えて該栄養細胞を増殖させる構成とを有することを特徴とする有機性廃水の処理装置。
【００２８】
（請求項１０）汚泥改質槽の溶存酸素濃度を０．１〜１．０ppmの範囲に調整する手段を有し、且つ処理槽の溶存酸素濃度を０．２〜２ppmの範囲に調整する手段を有することを特徴とする請求項９記載の有機性廃水の処理装置。
【００２９】
（請求項１１）処理槽が、空気供給手段を有する曝気槽からなり、該曝気槽は、２段以上の多段の槽からなり、後段の槽から第１段の槽に汚泥を返送する手段を有することを特徴とする請求項９又は１０記載の有機性廃水の処理装置。
【００３０】
（請求項１２）処理槽に、内生胞子形成細菌の胞子発芽促進物質を添加する手段を有することを特徴とする請求項９、１０又は１１記載の有機性廃水の処理装置。
【００３１】
（請求項１３）内生胞子形成細菌の胞子発芽促進物質が、アミノ酸、ポリペプチド又は糖質のうちの少なくとも１種であることを特徴とする請求項１２記載の有機性廃水の処理装置。
【００３２】
（請求項１４）アミノ酸が、Ｌ−アラニン、Ｌ−アスパラギン、Ｌ−イソロイシン、Ｌ−チロシン、ＤＬ−バリン、ＤＬ−アスパラギン酸又はカサアミノ酸から選ばれる少なくとも１種であることを特徴とする請求項１３記載の有機性廃水の処理装置。
【００３３】
（請求項１５）糖質が、Ｄ−グルコース、ガラクトース、フルクトース、マンノース、マルトース、多糖類、オリゴ糖又は糖類の加水分解物から選ばれる少なくとも１種であることを特徴とする請求項１３記載の有機性廃水の処理装置。
【００３４】
【発明の実施の形態】
以下、本発明の実施の形態を説明する。
【００３５】
本発明の好気性生物処理としては、曝気槽やオキシデーションディッチ等の処理槽を用いた処理が例示的に挙げられるが、以下の説明では曝気槽を用いた好気性生物処理について主に説明する。
【００３６】
図１は本発明の有機性廃水の処理方法を実施するための処理装置の一例を示す図であり、同図において、１は曝気槽、２は固液分離手段の一例である固液分離槽、３は汚泥改質槽である。
【００３７】
曝気槽１は処理系の前段に設けられ、本実施の形態では４段の槽１ａ，１ｂ，１ｃ，１ｄによって構成された例が示されている。４段の槽に構成する手段は特に限定されないが、１つの水槽を上下方向の３つの仕切部によって仕切り４つの槽に分けることが一般的に採用される。前段の側の槽から順に第１段槽１ａ、第２段槽１ｂ、第３段槽１ｃ、第４段槽１ｄと指称する。本発明では第１段槽１ａ→第２段槽１ｂ→第３段槽１ｃ→第４段槽１ｄの順に自然流下できるように、各槽の液面を調整することが好ましい。液の輸送コストを低減できるからである。
【００３８】
本実施の形態では、第２段槽１ｂから第１段槽１ａに向かって液を返送する返送ライン１１を設ける態様が採用されている。返送手段としては、図示しないエアーリフトによる方法を採用したが、本手段に限定されない。
【００３９】
曝気槽１を構成する各槽には、有機物分解の担い手である好気性微生物に酸素を供給するために図示しない空気供給手段が設けられている。空気供給量は、適正な微生物構造の維持や経済性を考慮して、決定、管理されるが、本発明では、内生胞子形成細菌の機能を十分に発揮させ、効果を得るために、曝気槽の溶存酸素濃度は０．２〜２ppmの範囲であることが好ましい。過剰に酸素が存在する場合は糸状菌等の好ましくない微生物の増殖を促し、また酸素が不足する場合は、内生胞子形成細菌の活性に悪影響を及ぼす。
【００４０】
空気供給手段は、ブロア等から供給される空気を導入して曝気槽内で散気できる構成であればよく、また曝気槽の溶存酸素濃度を０．２〜２ppmの範囲に調整する手段は、たとえばブロアの回転数を制御する手段、コントロールバルブ等による空気量制御手段等のいずれでもよい。
【００４１】
本発明では、固液分離槽２の下部より汚泥引き抜きポンプ２０により引き抜き、その引き抜いた汚泥を前記曝気槽１の前段に位置する汚泥改質槽３に返送する。汚泥改質槽３内では返送された活性汚泥中に含まれる非生物性の残存有機物が活性汚泥中の微生物によって資化され、消滅すると共に、汚泥中に含まれる内生胞子形成細菌の胞子が活性汚泥のフロックより遊離する。
【００４２】
汚泥改質槽３に導く汚泥量は処理系に導入される有機性廃水量の２〜５倍量とすることが重要で、２倍量未満では、活性汚泥中に含まれる非生物性残存有機物の資化、消滅が不十分であり、また５倍量を越えると、汚泥返送に要するエネルギーが増加し、経済性を害する。
【００４３】
また汚泥改質槽３内の溶存酸素濃度は０．１〜１．０ppmの範囲が活性汚泥フロックの過度な解体を防止する観点から好ましい。
【００４４】
更に、汚泥改質槽３内における汚泥の滞留時間は、非生物性の残存有機物の資化、消滅及び胞子形成細菌の胞子の活性汚泥フロックからの遊離の観点から１Hr以上が好ましく、また、過度なタンク容量を排除する観点から４Hr以下が好ましい。
【００４５】
上記汚泥改質槽３で改質された汚泥は曝気槽１に送られ、好気処理される。曝気槽１では処理対象となる有機性廃水が導入され、活性汚泥によって有機物等の分解が始まる。また同時に汚泥改質槽３から送り込まれた返送汚泥中に含まれる内生胞子形成細菌（好ましくはバチルス属細菌）の胞子は、有機性廃水中に含まれるアミノ酸、ポリペプチド、糖質等の発芽促進物質の作用により栄養細胞に転換される。
【００４６】
栄養細胞に転換し、活性化された内生胞子形成細菌はその高い有機物分解能力によって廃水中の有機物を効率的に分解すると共にその産出する有益な酵素によって、汚泥を構成する微生物の可溶化が起こり、発生汚泥量を著しく減少させることができる。
【００４７】
特に、曝気槽が２段以上の槽によって構成される場合には、後段の曝気槽内の一部汚泥を第１段の曝気槽に返送すれば、発芽が未完であった内生胞子形成細菌の発芽を促し、水処理を更に効果的に実施することができる。かかる効果を発揮する理由ないし原因は、曝気槽内で処理対象となる有機性廃水中の有機物の分解が進行し、糖、アミノ酸等の発芽促進物質が生成され、これらの物質が第１段の曝気槽に返送されることによって、胞子発芽を促進するものと考えられる。
【００４８】
また本発明では、発芽促進を更に加速するために、処理槽の一例である曝気槽１に、発芽促進物質添加手段１０から内生胞子形成細菌の胞子発芽促進物質を添加することが好ましい。
【００４９】
内生胞子形成細菌の胞子発芽促進物質としては、アミノ酸、ポリペプチド又は糖質のうちの少なくとも１種であることが好ましい。
【００５０】
アミノ酸としては、Ｌ−アラニン、Ｌ−アスパラギン、Ｌ−イソロイシン、Ｌ−チロシン、ＤＬ−バリン、ＤＬ−アスパラギン酸又はカサアミノ酸が好ましい例として挙げられ、これらの中から１種を選択して使用することもできるし、あるいは２種以上を組み合わせて使用することもできる。
【００５１】
糖質としては、Ｄ−グルコース、ガラクトース、フルクトース、マンノース、マルトース、多糖類、オリゴ糖又は糖類の加水分解物が好ましい例として挙げられ、これらの中から１種を選択して使用することもできるし、あるいは２種以上を組み合わせて使用することもできる。
【００５２】
内生胞子形成細菌の胞子発芽促進物質の添加量は、特に限定されないが、効果と経済性を考慮して、廃水量に対して５〜５０mg/lが適当である。
【００５３】
本発明では、前述のように曝気槽に供給される有機性廃水によって汚泥中の内生胞子形成細菌の胞子を発芽させて栄養細胞に転換するが、更に発芽した内生胞子形成細菌の増殖を促し、その有機物の分解能力を更に増加させるために、ケイ素とマグネシウムを含む単一又は複合の化合物を添加する。
【００５４】
これらの化合物としては、ケイ酸、ケイ酸マグネシウム、硫酸マグネシウム等が挙げられる。
【００５５】
添加場所は、処理槽の一例である曝気槽１に添加することが好ましく、更に曝気槽１が多段の槽からなる場合には、第１段の槽１ａに添加することが好ましい。なお、曝気槽１以外の場所に添加する場合、汚泥改質槽３に添加することもできる。
【００５６】
添加量は廃水量に対して、Ｓｉ（ケイ素）、Ｍｇ(マグネシウム)として、１〜５mg/lの範囲が好ましい。
【００５７】
以上の説明は好気性処理槽として曝気槽を用いた例について説明したが、曝気槽に代えてオキシディーションデッチのように流れ方向に連続的に処理する方式でも、後方の汚泥を前方に返送することによって同様の効果が得られる。
【００５８】
また固液分離手段は、前述のような沈殿槽、沈殿池、固液分離槽などの重力式の分離手段以外に、汚泥と処理水に分離できれば、膜を利用した分離手段であってもよい。
【００５９】
【発明の効果】
本発明によると、効果的に発生汚泥量を減少させると共に固液分離工程における正常な固液分離を容易ならしめ、また余剰汚泥の脱水性を向上させることができる。
【００６０】
また本発明によると、先提案の技術を更に改良し、汚泥のより一層の脱水性向上、及び経済性の向上のために、内生胞子形成細菌の機能活用をはかり、装置の適正な運転管理法を提供できる。
【００６１】
【実施例】
以下、実施例によって本発明を更に詳細に説明するが、本発明はかかる実施例によって限定されるものではない。
【００６２】
実施例１
図１に示す曝気槽（３．６ｍ³）と沈殿槽（０．９ｍ³）及び汚泥改質槽（１．４ｍ³）からなる処理装置を用いて下水処理の実験を実施した。
【００６３】
下水の成分分析値はＢＯＤ約２００ppm、Ｔ−Ｎ(全窒素)約３０ppm、Ｔ−Ｐ（全リン）約６ppmであった。
【００６４】
下水は夾雑物を除去した後、曝気槽へ投入され処理される。曝気槽は直列に連なった同容量の４槽からなっている。各々の槽を第１段槽、第２段槽、第３段槽、第４段槽と指称する。
【００６５】
曝気槽の運転は以下のように行った。即ち、曝気槽中の汚泥濃度はＭＬＳＳ４０００mg/l程度であり、水力学的滞留時間は８Hrとし、槽内の溶存酸素濃度は０．４〜０．８mg/lに調整し、汚泥中の内生胞子形成細菌の活性化のために可溶性ケイ酸及び硫酸マグネシウムを処理対象下水に対して、Ｓｉとして２mg/l、Ｍｇとして１mg/lとなるように各々添加した。
【００６６】
また第２段槽から第１段槽への汚泥返送比（＝汚泥返送量／流入下水量）は１となるようにして運転した。
【００６７】
流入下水は曝気槽で処理された後、固液分離槽（沈殿槽）へ送られ、重力沈降によって処理水と汚泥に分離され、処理水は系外に放流される。
【００６８】
一方、沈降した汚泥は汚泥返送ポンプによって沈殿槽の下部から汚泥改質槽へ返送される。この際の汚泥返送比（＝汚泥返送量／流入下水量）は２．５の条件で運転を行い、汚泥改質槽における汚泥の水力学的滞留時間は１．３Hrであり、汚泥改質槽内の溶存酸素濃度は０．３mg/lである。
【００６９】
以上の運転条件で、１ヶ月間の運転を行った。
【００７０】
運転開始から運転終了まで、曝気槽汚泥について、ＳＶＩ、ＭＬＳＳ、ＣＳTテストによる脱水性評価、バチルス属全細菌数及び胞子数を測定した。
【００７１】
汚泥改質槽についてもバチルス属全細菌数及び胞子数を測定し、運転状況及び汚泥性状について解析を行った。処理水についてはＢＯＤ、Ｔ−Ｎを測定し、解析に供した。
【００７２】
汚泥の増減は余剰汚泥発生率として次式により算出した。
【００７３】
余剰汚泥発生率（％）
＝(運転終了時のMLSS−運転開始時のMLSS)×100／運転開始時のMLSS
ここで、ＭＬＳＳの単位はmg/lである。
【００７４】
汚泥改質槽及び曝気槽の内生胞子形成細菌の発芽状況については発芽率として次式により算出した。
【００７５】
発芽率（％）
＝（バチルス属細菌全菌数−バチルス属胞子菌数）×100／バチルス属細菌全菌数
以上の測定結果を以下に示す。
【００７６】
（曝気槽）
第４段槽の運転終了時のＳＶＩ＝１６８
余剰汚泥発生率＝７．９％
第４段槽のＣＳＴ値＝３９．０(sec)
【００７７】
（汚泥改質槽）
ＣＳＴ値＝３７．４(sec)
【００７８】
（微生物の解析結果）
汚泥改質槽汚泥中のバチルス属細菌の発芽率＝２３％
曝気槽第１段槽汚泥中の発芽率＝８２％
この結果、曝気槽第１段槽でのバチルス属細菌胞子が発芽・活性化し、バチルス属細菌にとって栄養の乏しい汚泥改質槽においては、胞子化が進行していることが確認された。
【００７９】
（処理水の水質）
ＢＯＤ＝５ppm
Ｔ−Ｎ＝１８ppm
【００８０】
実施例２
実施例１と同様の処理装置を用い、曝気槽中の汚泥濃度はＭＬＳＳ４０００mg/l程度に維持し、水力学的滞留時間８Hr、槽内の溶存酸素濃度は０．４〜１．０mg/l、第２槽から第１槽への汚泥返送比（＝汚泥返送量／流入下水量）は１となるように汚泥を返送して、下水処理の運転を行った。
【００８１】
汚泥中の内生胞子形成細菌の活性化のために可溶性ケイ酸及び硫酸マグネシウムを処理対象下水に対して、Ｓｉとして２mg/l、Ｍｇとして２mg/lとなるように各々添加した。
【００８２】
一方、汚泥改質槽への汚泥返送比（＝汚泥返送量／流入下水量）は３．０の条件で運転を行い、汚泥改質槽における汚泥の水力学的滞留時間は１．０Hrであり、汚泥改質槽内の溶存酸素濃度は０．５mg/lとして運転を行った。
【００８３】
また発芽促進物質としてＬ−アラニンを曝気槽第１段槽に流入下水量に対して５mg/l添加した。
【００８４】
以上の運転条件で、１ヶ月間の運転を行ない、実施例１と同様に解析、評価し、その測定結果を以下に示す。
【００８５】
（曝気槽）
第４段槽の運転終了時のＳＶＩ＝１６０
余剰汚泥発生率＝６．５％
第４段槽のＣＳＴ値＝３３．３(sec)
【００８６】
（汚泥改質槽）
ＣＳＴ値＝３１．９(sec)
【００８７】
（微生物の解析結果）
汚泥改質槽汚泥中のバチルス属細菌の発芽率＝２２％
曝気槽第１段槽汚泥中の発芽率＝８８％
この結果、発芽促進物質の添加により、曝気槽第１段槽でのバチルス属細菌胞子が発芽・活性化が促進された。
【００８８】
（処理水の水質）
ＢＯＤ＝４ppm
Ｔ−Ｎ＝１７ppm
【００８９】
比較例１
実施例１で用いた処理装置から、汚泥改質槽を除いた以外は同様の処理装置を用い、曝気槽中の汚泥濃度はＭＬＳＳ４０００mg/l程度に維持し、沈殿槽から直接曝気槽に汚泥を返送した。汚泥返送比は１とした。
【００９０】
曝気槽内での水力学的滞留時間８Hr、槽内の溶存酸素濃度は０．４〜１．０mg/l、第２段槽から第１段槽への汚泥返送比（＝汚泥返送量／流入下水量）は１となるように汚泥を返送して、下水処理の運転を行った。
【００９１】
汚泥中の内生胞子形成細菌の活性化のために可溶性ケイ酸及び硫酸マグネシウムを処理対象下水に対して、Ｓｉとして２mg/l、Ｍｇとして１mg/lとなるように各々添加した。
【００９２】
以上の運転条件で、１ヶ月間の運転を行ない、実施例１と同様に解析、評価し、その測定結果を以下に示す。
【００９３】
（曝気槽）
第４段槽の運転終了時のＳＶＩ＝２３０
余剰汚泥発生率＝４４．５％
第４段槽のＣＳＴ値＝１１８(sec)
【００９４】
（微生物の解析結果）
曝気槽第１段槽汚泥中の発芽率＝１９％
この結果、実施例１と比べ、汚泥の沈降性不良が認められ、余剰汚泥発生率も高く、発芽率もかなり低いことがわかる。
【００９５】
（処理水の水質）
ＢＯＤ＝４ppm
Ｔ−Ｎ＝１７ppm
この結果、実施例１に比べ、処理効率が悪いことがわかる。
【図面の簡単な説明】
【図１】本発明の実施の形態を示す図
【符号の説明】
１：曝気槽
２：固液分離槽
３：汚泥改質槽
１０：発芽促進物質添加手段
２０：返送汚泥ポンプ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for treating organic wastewater such as sewage, and more specifically, the amount of biological sludge generated in large quantities as a result of biological treatment can be significantly reduced, and the coagulation sedimentation and dewaterability of activated sludge can be improved. The present invention relates to a method and apparatus for treating organic wastewater that contributes to improving the operability and economic efficiency of activated sludge treatment facilities.
[0002]
[Prior art]
The treatment of organic wastewater such as sewage is generally carried out by biological treatment methods such as the activated sludge method. In the biological treatment method, the organic matter in the sewage is catabolized and assimilated by the organism and removed from the water.
[0003]
However, assimilated organic matter accumulates in the sludge. That is, the amount of sludge increases, and disposal of this sludge results in an increase in processing costs. Many methods for reducing the amount of generated sludge have been proposed to deal with such problems.
[0004]
As a method for reducing the amount of generated sludge by a biological treatment method, there are a long-time aeration method and a biofilm method. These methods are methods for suppressing the amount of generated sludge by controlling operating variables such as organic load and residence time.
[0005]
On the other hand, there has been proposed a method for reducing the amount of generated sludge by destroying and solubilizing microbial cells in activated sludge and then biologically treating them in a treatment tank and making them inorganic. As a solubilization technique, many methods such as heat treatment, acid-alkali treatment, chemical oxidation treatment, mechanical pulverization treatment, enzyme treatment, and microbial treatment have been proposed. For example, JP-A-8-103786 discloses a method for significantly reducing the amount of excess sludge by ozone-oxidizing and solubilizing a part of the returned sludge and then returning it to the treatment tank. Similarly, a method for solubilizing at a high temperature is disclosed in JP-A-9-10791.
[0006]
In addition, sludge coagulation sedimentation is the most important factor in operation management in the activated sludge process where natural sedimentation separates sludge and treated water, and operation managers require a great deal of labor to maintain this coagulation sedimentation. This is the current situation. Once the coagulation sedimentation property has deteriorated, an attempt may be made to add a drug in order to urgently recover the treated water quality. Furthermore, the sludge discharged as surplus sludge is subjected to a dehydration process and then sent to a post-treatment process such as incineration and composting. In the dehydration process, expensive chemicals are used to achieve a predetermined moisture content. The reality is.
[0007]
[Problems to be solved by the invention]
However, the method of reducing the amount of generated sludge by the biological treatment method has a small amount of sludge reduction and usually reduces the amount of organic matter treated per treatment tank, so that the treatment efficiency is deteriorated.
[0008]
Moreover, when adopting the sludge solubilization treatment step, it is necessary to destroy the microbial cells that are the main component of the sludge. For this destruction, the above-described methods (methods described in JP-A-8-103786 and JP-A-9-10791) are used, but the cell walls covering the microbial cells are quite strong and mild processing conditions are used. Then, there is a problem that the cell wall is not destroyed and the solubilization treatment becomes insufficient.
[0009]
On the other hand, in order to satisfy the effect of the solubilization treatment, a large amount of energy is required, which causes a problem that is economically disadvantageous.
[0010]
Further, in the method of performing solid-liquid separation of sludge and treated water by the natural sedimentation method, there is a problem of operation cost increase due to the operation management and the use of chemicals in consideration of the coagulation sedimentation property of the sludge. Furthermore, if the dewaterability of sludge is poor, it is essential to use chemicals in the dewatering process, resulting in a deterioration in economic efficiency.
[0011]
Therefore, the object of the present invention is to solve the above conventional problems, effectively reduce the amount of generated sludge, facilitate normal solid-liquid separation in the solid-liquid separation process, and improve the dewaterability of excess sludge. An object of the present invention is to provide an organic wastewater treatment method and treatment apparatus.
[0012]
Other objects of the present invention will become apparent from the following description.
[0013]
[Means for Solving the Problems]
It is well known that biological treatment of organic wastewater is performed by the interaction between various microorganisms in activated sludge, and the action of bacteria is considered to be important among microorganisms. However, although the existence of various bacteria in activated sludge has been confirmed, not all of them have been clarified, and the functions of individual bacteria are actively utilized and controlled for application to wastewater treatment. Some examples are limited to nitrogen removal. Under such circumstances, Bacillus bacteria among endospore-forming bacteria are considered to be extremely useful bacteria for treating organic wastewater because of the high ability of the enzymes produced to decompose organic matter.
[0014]
However, although Bacillus spp. Are recognized as general bacteria contained in activated sludge, there are no examples of fully elucidating, controlling and utilizing their ecology.
[0015]
In view of such points, the present inventors previously described Japanese Patent Application 2000- as a technique for elucidating and controlling the ecology of endospore-forming bacteria, particularly bacteria belonging to the genus Bacillus, and sufficiently exerting its function in activated sludge. No. 102533 (hereinafter referred to as the previously proposed technology) was proposed.
[0016]
That is, endospore-forming bacteria represented by Bacillus genus are transformed from vegetative cells to spores and from spores to vegetative cells depending on their living environment. Produces cell wall lytic enzymes. Furthermore, Bacillus bacteria produce α-amylase and protease as extracellular enzymes at the stage from vegetative cells to spores. By utilizing the action and effects of these enzymes, organic substances in wastewater are effectively decomposed, and some of the microorganisms that make up sludge are dissolved and utilized by other living microorganisms to become mineralized. This makes it possible to significantly reduce the amount of generated sludge. Moreover, by decomposing the highly hydrophilic organic substance contained in the sludge, it becomes possible to prevent the sludge from swelling and prevent the sludge from coagulating and settling.
[0017]
In order to express these functions, the previously proposed technology converts endospore-forming bacteria spores into vegetative cells in the presence of germination-promoting substances such as amino acids, peptides and carbohydrates, and endospore formation. The process of converting to a spore state in an environment where nutrient substances capable of assimilating vegetative cells of bacteria are reduced is incorporated into the water treatment process.
[0018]
The present inventors have further improved the previously proposed technique, and have found a specific means for utilizing the functions of endospore-forming bacteria in order to further improve sludge dehydration and economy. Invented.
[0019]
That is, this invention which solves the said subject has the following structures.
(Claim 1) In a method for treating organic wastewater, which has a treatment tank in the front stage of the treatment system and has solid-liquid separation means in the latter stage, and introduces organic wastewater into the treatment system and performs aerobic biological treatment. The sludge containing the spores of endospore-forming bacteria extracted from the solid-liquid separation means is located in the front stage of the treatment tank , and assimilates and extinguishes the abiotic residual organic matter in the sludge and eliminates the spore-forming bacteria. When the spore is led from the activated sludge floc to the sludge reforming tank and then led to the treatment tank , the organic waste water is not treated in the sludge reforming tank without introducing the organic waste water. The amount of sludge introduced into the tank and guided to the sludge reforming tank is 2.5 to 5 times the amount of organic wastewater introduced into the treatment system, and further the organic wastewater supplied to the treatment tank Spores of living spore-forming bacteria are germinated and converted into vegetative cells, silicon and magnesium Single or the method of treating organic wastewater by adding a complex of a compound which comprises treating the organic wastewater while growing the vegetative cells including.
[0020]
(Claim 2) The dissolved oxygen concentration of the sludge reforming tank is in the range of 0.1 to 1.0 ppm, and the dissolved oxygen concentration of the treatment tank is in the range of 0.2 to 2 ppm. Item 10. A method for treating organic wastewater according to Item 1.
[0021]
(Claim 3) The treatment tank comprises an aeration tank having an air supply means, the aeration tank comprises two or more multi-stage tanks, and sludge is returned from the latter tank to the first tank. The method for treating organic wastewater according to claim 1 or 2, characterized in that:
[0022]
(Claim 4) The method for treating organic wastewater according to claim 1, 2 or 3, wherein a spore germination promoting substance of endospore-forming bacteria is added to the treatment tank.
[0023]
(5) The method for treating organic wastewater according to (4), wherein the spore germination promoting substance of the endospore-forming bacterium is at least one of amino acids, polypeptides or carbohydrates.
[0024]
(Claim 6) The amino acid is at least one selected from L-alanine, L-asparagine, L-isoleucine, L-tyrosine, DL-valine, DL-aspartic acid or Casa amino acid. 5. A method for treating organic wastewater according to 5.
[0025]
(7) The saccharide is at least one selected from D-glucose, galactose, fructose, mannose, maltose, polysaccharide, oligosaccharide or saccharide hydrolyzate. Organic wastewater treatment method.
[0026]
(8) The method for treating organic wastewater according to any one of (1) to (7), wherein the endospore-forming bacteria are Bacillus bacteria.
[0027]
(Claim 9) In an organic wastewater treatment apparatus which has a treatment tank in the previous stage of the treatment system and has a solid-liquid separation means in the latter stage and introduces organic wastewater into the treatment system and performs aerobic biological treatment Introducing the sludge extracted from the solid-liquid separation means without introducing organic wastewater into the previous stage of the treatment tank, assimilating and extinguishing the non-biological residual organic matter in the sludge, and spore of spore-forming bacteria A sludge reforming tank that releases the activated sludge floc from the solid-liquid separation means, a means for extracting sludge containing spores of endospore-forming bacteria, and a sludge extracted by the extraction means in the treatment tank. 1. Means for guiding to a sludge reforming tank located in the preceding stage; means for guiding from the sludge reforming tank to the treatment tank; and amount of organic waste water introduced into the treatment system by the amount of sludge leading to the sludge reforming tank . Means for adjusting the amount to 5 to 5 times, and further provided to the treatment tank. A structure in which the spores of endospore-forming bacteria in the sludge are germinated by the supplied organic wastewater and converted to vegetative cells, and a structure in which the vegetative cells are grown by adding a single or complex compound containing silicon and magnesium An organic wastewater treatment apparatus characterized by comprising:
[0028]
(Claim 10) Means for adjusting the dissolved oxygen concentration of the sludge reforming tank to a range of 0.1 to 1.0 ppm and adjusting the dissolved oxygen concentration of the treatment tank to a range of 0.2 to 2 ppm The apparatus for treating organic wastewater according to claim 9, wherein:
[0029]
(Claim 11) The treatment tank is composed of an aeration tank having air supply means, the aeration tank is composed of two or more multi-stage tanks, and means for returning sludge from the latter tank to the first tank. The apparatus for treating organic wastewater according to claim 9 or 10, characterized by comprising:
[0030]
(Claim 12) The apparatus for treating organic wastewater according to claim 9, 10 or 11, further comprising means for adding a spore germination promoting substance of endospore-forming bacteria to the treatment tank.
[0031]
(13) The organic wastewater treatment apparatus according to the above (12), wherein the spore germination promoting substance of the endospore-forming bacterium is at least one of amino acids, polypeptides or carbohydrates.
[0032]
(Claim 14) The amino acid is at least one selected from L-alanine, L-asparagine, L-isoleucine, L-tyrosine, DL-valine, DL-aspartic acid or Casa amino acid. The organic wastewater treatment apparatus as described in Item 13.
[0033]
(15) The carbohydrate according to (13), wherein the carbohydrate is at least one selected from D-glucose, galactose, fructose, mannose, maltose, polysaccharides, oligosaccharides or saccharide hydrolysates. Organic wastewater treatment equipment.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0035]
As an aerobic biological treatment of the present invention, a treatment using a treatment tank such as an aeration tank or an oxidation ditch is exemplified, but in the following description, aerobic biological treatment using an aeration tank will be mainly described. .
[0036]
FIG. 1 is a view showing an example of a treatment apparatus for carrying out the organic wastewater treatment method of the present invention. In the figure, 1 is an aeration tank, and 2 is a solid-liquid separation tank which is an example of a solid-liquid separation means. 3 is a sludge reforming tank.
[0037]
The aeration tank 1 is provided in the front stage of the processing system, and in this embodiment, an example constituted by four stages of tanks 1a, 1b, 1c, and 1d is shown. The means for constituting the four-stage tank is not particularly limited, but it is generally adopted that one water tank is divided into four tanks by three partition parts in the vertical direction. The first-stage tank 1a, the second-stage tank 1b, the third-stage tank 1c, and the fourth-stage tank 1d are referred to in order from the previous-stage tank. In the present invention, it is preferable to adjust the liquid level of each tank so that it can naturally flow in the order of the first stage tank 1a → second stage tank 1b → third stage tank 1c → fourth stage tank 1d. This is because the liquid transportation cost can be reduced.
[0038]
In this Embodiment, the aspect which provides the return line 11 which returns a liquid toward the 1st stage tank 1a from the 2nd stage tank 1b is employ | adopted. As the returning means, a method using an air lift (not shown) is adopted, but it is not limited to this means.
[0039]
Each tank constituting the aeration tank 1 is provided with an air supply means (not shown) for supplying oxygen to aerobic microorganisms which are responsible for organic matter decomposition. The air supply amount is determined and managed in consideration of the maintenance of an appropriate microbial structure and economy, but in the present invention, in order to sufficiently exert the function of endospore-forming bacteria and obtain an effect, aeration is performed. The dissolved oxygen concentration in the tank is preferably in the range of 0.2 to 2 ppm. When oxygen is excessively present, it promotes the growth of undesirable microorganisms such as filamentous fungi, and when oxygen is insufficient, the activity of endospore-forming bacteria is adversely affected.
[0040]
The air supply means only needs to be configured so that air supplied from a blower or the like can be diffused in the aeration tank, and means for adjusting the dissolved oxygen concentration in the aeration tank to a range of 0.2 to 2 ppm, For example, any of a means for controlling the rotation speed of the blower, an air amount control means by a control valve or the like may be used.
[0041]
In the present invention, the sludge extraction pump 20 draws the sludge from the lower part of the solid-liquid separation tank 2, and the extracted sludge is returned to the sludge reforming tank 3 located in the preceding stage of the aeration tank 1. In the sludge reforming tank 3, the abiotic residual organic matter contained in the returned activated sludge is assimilated and disappeared by microorganisms in the activated sludge, and the spores of endospore-forming bacteria contained in the sludge are removed. Free from activated sludge flocs.
[0042]
It is important that the amount of sludge introduced to the sludge reforming tank 3 is 2 to 5 times the amount of organic waste water introduced into the treatment system. If the amount is less than 2 times, the abiotic residual organic matter contained in the activated sludge If the amount exceeds 5 times, energy required for returning the sludge increases and the economy is impaired.
[0043]
Further, the dissolved oxygen concentration in the sludge reforming tank 3 is preferably in the range of 0.1 to 1.0 ppm from the viewpoint of preventing excessive dismantling of the activated sludge floc.
[0044]
Furthermore, the residence time of the sludge in the sludge reforming tank 3 is preferably 1 Hr or more from the viewpoints of utilization and extinction of non-biological residual organic matter and release of spores of the spore-forming bacteria from the activated sludge floc. From the viewpoint of eliminating a large tank capacity, 4 Hr or less is preferable.
[0045]
The sludge modified in the sludge reforming tank 3 is sent to the aeration tank 1 for aerobic treatment. In the aeration tank 1, organic wastewater to be treated is introduced, and decomposition of organic substances and the like is started by activated sludge. At the same time, the spores of endospore-forming bacteria (preferably Bacillus spp.) Contained in the returned sludge sent from the sludge reforming tank 3 germinate amino acids, polypeptides, carbohydrates, etc. contained in the organic wastewater. It is converted to vegetative cells by the action of the stimulating substance.
[0046]
Endospore-forming bacteria that have been converted to vegetative cells and activated efficiently decompose organic matter in wastewater by virtue of their high organic matter-degrading ability, and solubilize microorganisms that make up sludge by the beneficial enzymes produced. This can significantly reduce the amount of sludge generated.
[0047]
In particular, when the aeration tank is composed of two or more tanks, if part of the sludge in the latter aeration tank is returned to the first aeration tank, germination has not been completed. Germination of water can be promoted and water treatment can be carried out more effectively. The reason or cause for exerting such an effect is that decomposition of organic substances in the organic wastewater to be treated proceeds in the aeration tank, and germination promoting substances such as sugars and amino acids are generated. It is considered that spore germination is promoted by being returned to the aeration tank.
[0048]
In the present invention, in order to further accelerate the germination, the aeration tank 1, which is an example of a processing tank, it is preferable to add a spore germination material endospore forming bacteria from germination promoting agent adding means 10.
[0049]
The spore germination promoting substance of endospore-forming bacteria is preferably at least one of amino acids, polypeptides or carbohydrates.
[0050]
Examples of the amino acid include L-alanine, L-asparagine, L-isoleucine, L-tyrosine, DL-valine, DL-aspartic acid and Casa amino acid, and one of these is selected and used. It can also be used, or two or more kinds can be used in combination.
[0051]
Preferred examples of the saccharide include D-glucose, galactose, fructose, mannose, maltose, polysaccharides, oligosaccharides, or saccharide hydrolysates, and one of these can be selected and used. Alternatively, two or more types can be used in combination.
[0052]
Although the addition amount of the spore germination promoting substance of the endospore-forming bacteria is not particularly limited, 5 to 50 mg / l is appropriate with respect to the amount of waste water in consideration of the effect and economy.
[0053]
In the present invention, the spore of endospore-forming bacteria in the sludge is germinated and converted into vegetative cells by the organic wastewater supplied to the aeration tank as described above. To facilitate and further increase the ability to decompose the organic matter, single or multiple compounds containing silicon and magnesium are added.
[0054]
Examples of these compounds include silicic acid, magnesium silicate, magnesium sulfate and the like.
[0055]
The place of addition is preferably added to the aeration tank 1 which is an example of the treatment tank, and when the aeration tank 1 is composed of a multistage tank, it is preferably added to the first stage tank 1a. In addition, when adding to places other than the aeration tank 1, it can also add to the sludge reforming tank 3. FIG.
[0056]
The addition amount is preferably in the range of 1 to 5 mg / l as Si (silicon) or Mg (magnesium) with respect to the amount of waste water.
[0057]
Although the above explanation explained the example using the aeration tank as the aerobic treatment tank, the sludge on the back is also returned to the front even in the method of processing continuously in the flow direction like an oxidation tank instead of the aeration tank. By doing so, the same effect can be obtained.
[0058]
The solid-liquid separation means may be a separation means using a membrane as long as it can be separated into sludge and treated water in addition to the gravity-type separation means such as the settling tank, the settling tank, and the solid-liquid separation tank as described above. .
[0059]
【The invention's effect】
According to the present invention, it is possible to effectively reduce the amount of generated sludge, facilitate normal solid-liquid separation in the solid-liquid separation step, and improve the dewaterability of excess sludge.
[0060]
In addition, according to the present invention, in order to further improve the previously proposed technology, further improve the dehydration of sludge, and improve the economic efficiency, the functions of endospore-forming bacteria are utilized, and proper operation management of the apparatus is performed. Can provide law.
[0061]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by this Example.
[0062]
Example 1
A sewage treatment experiment was conducted using a treatment apparatus comprising an aeration tank (3.6 m ³ ), a precipitation tank (0.9 m ³ ) and a sludge reforming tank (1.4 m ³ ) shown in FIG.
[0063]
The component analysis values of sewage were about 200 ppm BOD, about 30 ppm TN (total nitrogen), and about 6 ppm TP (total phosphorus).
[0064]
After removing impurities, the sewage is put into an aeration tank and processed. The aeration tank consists of four tanks of the same capacity connected in series. Each tank is referred to as a first tank, a second tank, a third tank, and a fourth tank.
[0065]
The aeration tank was operated as follows. That is, the sludge concentration in the aeration tank is about MLSS 4000 mg / l, the hydraulic residence time is 8 hours, the dissolved oxygen concentration in the tank is adjusted to 0.4 to 0.8 mg / l, In order to activate the spore-forming bacteria, soluble silicic acid and magnesium sulfate were added to the sewage to be treated at 2 mg / l as Si and 1 mg / l as Mg, respectively.
[0066]
The sludge return ratio from the second stage tank to the first stage tank (= sludge return amount / inflow sewage amount) was set to 1.
[0067]
Inflow sewage is treated in an aeration tank, then sent to a solid-liquid separation tank (sedimentation tank), separated into treated water and sludge by gravity sedimentation, and the treated water is discharged out of the system.
[0068]
On the other hand, the settled sludge is returned from the lower part of the settling tank to the sludge reforming tank by a sludge return pump. In this case, the sludge return ratio (= sludge return amount / inflow sewage amount) is operated under the condition of 2.5, the sludge hydrodynamic residence time in the sludge reformer is 1.3 hours, and the sludge reformer The dissolved oxygen concentration is 0.3 mg / l.
[0069]
The operation was performed for one month under the above operating conditions.
[0070]
From the start of operation to the end of operation, aeration tank sludge was evaluated for dehydration by SVI, MLSS, and CST tests, and the total number of bacteria and spores in the genus Bacillus.
[0071]
In the sludge reforming tank, the total number of bacteria and the number of spores of Bacillus were measured, and the operating conditions and sludge properties were analyzed. About treated water, BOD and TN were measured and used for analysis.
[0072]
The increase / decrease in sludge was calculated by the following equation as the excess sludge generation rate.
[0073]
Surplus sludge generation rate (%)
= (MLSS at the end of operation-MLSS at the start of operation) x 100 / MLSS at the start of operation
Here, the unit of MLSS is mg / l.
[0074]
The germination rate of endospore-forming bacteria in the sludge reforming tank and aeration tank was calculated as the germination rate according to the following formula.
[0075]
Germination rate (%)
= (Total number of Bacillus bacteria-Number of Bacillus spores) x 100 / Measurement results over the total number of Bacillus bacteria are shown below.
[0076]
(Aeration tank)
SVI at end of operation of the 4th tank = 168
Surplus sludge generation rate = 7.9%
CST value of the 4th stage tank = 39.0 (sec)
[0077]
(Sludge reforming tank)
CST value = 37.4 (sec)
[0078]
(Microbial analysis results)
Germination rate of Bacillus bacteria in sludge reforming tank sludge = 23%
Germination rate in aeration tank first stage tank sludge = 82%
As a result, it was confirmed that the spores of Bacillus sp. Germinated and activated in the first stage tank of the aeration tank, and that the sporulation had progressed in the sludge reforming tank poor in nutrients for the Bacillus sp.
[0079]
(Water quality of treated water)
BOD = 5ppm
TN = 18ppm
[0080]
Example 2
Using the same treatment apparatus as in Example 1, the sludge concentration in the aeration tank is maintained at about MLSS 4000 mg / l, the hydraulic residence time is 8 hours, the dissolved oxygen concentration in the tank is 0.4 to 1.0 mg / l, The sludge was returned so that the sludge return ratio from the second tank to the first tank (= sludge return amount / inflow sewage amount) was 1, and the sewage treatment operation was performed.
[0081]
In order to activate endospore-forming bacteria in the sludge, soluble silicic acid and magnesium sulfate were added to the sewage to be treated at 2 mg / l as Si and 2 mg / l as Mg, respectively.
[0082]
On the other hand, the sludge return ratio (= sludge return amount / inflow sewage amount) to the sludge reforming tank is operated under the condition of 3.0, and the sludge hydrodynamic residence time in the sludge reforming tank is 1.0 hr. The operation was performed with the dissolved oxygen concentration in the sludge reforming tank being 0.5 mg / l.
[0083]
Further, L-alanine as a germination promoting substance was added to the first stage tank of the aeration tank at 5 mg / l with respect to the inflow sewage amount.
[0084]
The operation was performed for one month under the above operating conditions, analyzed and evaluated in the same manner as in Example 1, and the measurement results are shown below.
[0085]
(Aeration tank)
SVI at the end of operation of the 4th tank = 160
Excess sludge generation rate = 6.5%
CST value of the 4th stage tank = 33.3 (sec)
[0086]
(Sludge reforming tank)
CST value = 31.9 (sec)
[0087]
(Microbial analysis results)
Germination rate of Bacillus bacteria in sludge reforming tank sludge = 22%
Germination rate in the aeration tank first stage sludge = 88%
As a result, germination and activation of Bacillus spore bacteria in the first stage tank of the aeration tank was promoted by the addition of the germination promoting substance.
[0088]
(Water quality of treated water)
BOD = 4ppm
TN = 17ppm
[0089]
Comparative Example 1
The same treatment equipment is used except that the sludge reforming tank is removed from the treatment equipment used in Example 1, the sludge concentration in the aeration tank is maintained at about MLSS 4000 mg / l, and the sludge is directly fed from the precipitation tank to the aeration tank. I returned it. The sludge return ratio was 1.
[0090]
Hydrodynamic residence time in the aeration tank 8Hr, dissolved oxygen concentration in the tank 0.4-1.0mg / l, sludge return ratio from the second stage tank to the first stage tank (= sludge return amount / inflow) Sludge was returned so that the amount of sewage was 1, and the operation of sewage treatment was performed.
[0091]
In order to activate endospore-forming bacteria in the sludge, soluble silicic acid and magnesium sulfate were added to the sewage to be treated at 2 mg / l as Si and 1 mg / l as Mg, respectively.
[0092]
The operation was performed for one month under the above operating conditions, and analysis and evaluation were performed in the same manner as in Example 1. The measurement results are shown below.
[0093]
(Aeration tank)
SVI = 230 at the end of operation of the 4th tank
Surplus sludge generation rate = 44.5%
4th stage CST value = 118 (sec)
[0094]
(Microbial analysis results)
Germination rate in the aeration tank first stage tank sludge = 19%
As a result, it can be seen that, compared to Example 1, sludge sedimentation failure was observed, the excess sludge generation rate was high, and the germination rate was also quite low.
[0095]
(Water quality of treated water)
BOD = 4ppm
TN = 17ppm
As a result, it can be seen that the processing efficiency is lower than that of the first embodiment.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention.
1: Aeration tank 2: Solid-liquid separation tank 3: Sludge reforming tank 10: Germination promoting substance addition means 20: Return sludge pump

Claims

In the treatment method of organic wastewater having a treatment tank in the front stage of the treatment system and having a solid-liquid separation means in the latter stage and introducing the organic wastewater into the treatment system and aerobic biological treatment,
Sludge containing spores of endospore-forming bacteria extracted from the solid-liquid separation means is located in the front stage of the treatment tank , and assimilate and extinguish abiotic residual organic matter in the sludge, and spores of the spore-forming bacteria When led to the treatment tank after being led to the sludge reforming tank that releases from the activated sludge floc of
Without introducing organic wastewater into the sludge reforming tank, the organic wastewater is introduced into the treatment tank,
The amount of sludge introduced into the sludge reforming tank is 2.5 to 5 times the amount of organic wastewater introduced into the treatment system, and the organic spore-forming bacteria in the sludge are further reduced by the organic wastewater supplied to the treatment tank. A method for treating organic wastewater, comprising the steps of germinating spores to convert them into vegetative cells, and treating organic wastewater while growing the vegetative cells by adding a single or complex compound containing silicon and magnesium.

The dissolved oxygen concentration in the sludge reforming tank is in the range of 0.1 to 1.0 ppm, and the dissolved oxygen concentration in the treatment tank is in the range of 0.2 to 2 ppm. Of waste water.

The treatment tank is composed of an aeration tank having an air supply means, the aeration tank is composed of two or more stages of tanks, and sludge is returned from the latter stage tank to the first stage tank. The processing method of the organic waste water of 1 or 2.

The method for treating organic wastewater according to claim 1, 2, or 3, wherein a spore germination promoting substance of endospore-forming bacteria is added to the treatment tank.

The method for treating organic wastewater according to claim 4, wherein the spore germination promoting substance of the endospore-forming bacterium is at least one of amino acids, polypeptides or carbohydrates.

6. The organic material according to claim 5, wherein the amino acid is at least one selected from L-alanine, L-asparagine, L-isoleucine, L-tyrosine, DL-valine, DL-aspartic acid or Casa amino acid. Wastewater treatment method.

6. The organic wastewater treatment according to claim 5, wherein the saccharide is at least one selected from D-glucose, galactose, fructose, mannose, maltose, polysaccharides, oligosaccharides or hydrolysates of saccharides. Method.

The method for treating organic wastewater according to any one of claims 1 to 7, wherein the endospore-forming bacteria are Bacillus bacteria.

In a treatment apparatus for organic wastewater that has a treatment tank in the front stage of the treatment system and has a solid-liquid separation means in the latter stage, and introduces organic wastewater into the treatment system and performs aerobic biological treatment
Without introducing organic wastewater into the previous stage of the treatment tank, the sludge extracted from the solid-liquid separation means is led to assimilate and extinguish the abiotic residual organic matter in the sludge and eliminate the spores of the spore-forming bacteria. It has a sludge reforming tank that releases from activated sludge floc,
Means for extracting sludge containing spores of endospore-forming bacteria from the solid-liquid separation means; means for guiding the sludge extracted by the extraction means to a sludge reforming tank located in the preceding stage of the treatment tank; and the sludge reforming Means for guiding from the tank to the treatment tank, and means for adjusting the amount of sludge guided to the sludge reforming tank to 2.5 to 5 times the amount of organic waste water introduced into the treatment system, Organic sewage supplied to the tank allows germination of endospore-forming bacteria in the sludge and transforms them into vegetative cells, and the vegetative cells are grown by adding single or complex compounds containing silicon and magnesium. An organic wastewater treatment device characterized by comprising:

It has means for adjusting the dissolved oxygen concentration of the sludge reforming tank to a range of 0.1 to 1.0 ppm, and has means for adjusting the dissolved oxygen concentration of the treatment tank to a range of 0.2 to 2 ppm. The organic wastewater treatment apparatus according to claim 9.

The treatment tank is composed of an aeration tank having air supply means, the aeration tank is composed of two or more stages of tanks, and has means for returning sludge from the subsequent tank to the first tank. The organic wastewater treatment apparatus according to claim 9 or 10.

The apparatus for treating organic wastewater according to claim 9, 10 or 11, further comprising means for adding a spore germination promoting substance of endospore-forming bacteria to the treatment tank.

13. The apparatus for treating organic wastewater according to claim 12, wherein the spore germination promoting substance of the endospore-forming bacterium is at least one of amino acids, polypeptides or carbohydrates.

The organic acid according to claim 13, wherein the amino acid is at least one selected from L-alanine, L-asparagine, L-isoleucine, L-tyrosine, DL-valine, DL-aspartic acid or Casa amino acid. Waste water treatment equipment.

14. The treatment of organic wastewater according to claim 13, wherein the saccharide is at least one selected from D-glucose, galactose, fructose, mannose, maltose, polysaccharides, oligosaccharides or saccharide hydrolysates. apparatus.