JP4142138B2

JP4142138B2 - Microbial reaction tank and waste water treatment method

Info

Publication number: JP4142138B2
Application number: JP31764597A
Authority: JP
Inventors: 清治藤野
Original assignee: Japan ALSI Co Ltd
Current assignee: Japan ALSI Co Ltd
Priority date: 1997-11-03
Filing date: 1997-11-03
Publication date: 2008-08-27
Anticipated expiration: 2017-11-03
Also published as: KR19990043966A; JPH11128987A; KR100306665B1

Description

【０００１】
【発明の属する技術分野】
本発明は微生物反応槽および排水処理方法に関する。
【０００２】
【従来の技術】
し尿処理場やゴミ処理場より流出する排水は、ＢＯＤやＳＳ値を高める高濃度の窒素成分やリン成分、有機物質などの汚濁物質が含まれ、河川の汚染や赤潮発生等、環境汚染の原因となっている。
従来、このような高濃度の汚濁物質を含む排水の処理方法として、好気嫌気循環法の一つである、いわゆる修正バーナード法が知られている。修正バーナード法の一例を図３に示す。図３は修正バーナード法のフロー図である。この方法は、脱窒反応の際に遊離するアルカリを硝化反応で再利用するために、活性汚泥処理工程において、脱窒工程を第一硝化槽１５ａの前後に位置する第一脱窒槽１４ａと第二脱窒槽１４ｂの２段に分け、さらに第二脱窒槽１４ｂの後に第二硝化槽１５ｂを設け、第一および第二の硝化槽から流出する混合液を第一脱窒槽に循環する方法である。
【０００３】
【発明が解決しようとする課題】
しかしながら、し尿処理場やゴミ処理場から流出する排水は、通常排水の 10 倍から 100倍程度以上の高濃度の窒素成分を含み、またリン成分、有機物質などの汚濁物質も高濃度に含まれているので、その排水処理には次のような問題がある。
【０００４】
第一に、高濃度のアンモニア性窒素は、それ自身殺菌性を有するので、活性汚泥処理工程で活性汚泥の活性を阻害する場合が多い。このため、活性汚泥処理が不十分になるという問題がある。
【０００５】
第二に、いわゆる修正バーナード法などでは、硝化槽において硝化反応が進行するとｐＨが低下するが、硝化反応はｐＨに依存するのでｐＨが低下すると硝化反応が遅くなる。その結果、やはり活性汚泥処理が不十分になるという問題がある。活性汚泥処理が不十分となると、リンの除去なども不十分になるという問題がある。
【０００６】
第三に、活性汚泥処理が不十分で脱窒反応が遅くなると、残存アンモニアや硝酸イオン、亜硝酸イオン濃度等が高くなる結果、これら窒素化合物に依存するＢＯＤが高くなり、排水処理が不十分になるという問題がある。
【０００７】
第四に、高濃度汚濁物質含有排水では、高濃度の活性汚泥が必要となり、必然的に固形分濃度（ＭＬＳＳ）などが高くなる傾向にある。そのため、酸素の供給が困難になると共に、活性汚泥の攪拌が困難になったり、沈澱槽での固液分離が困難になるなどの問題がある。
【０００８】
第五に低い有機汚濁物質濃度にもかかわらず、高い窒素成分を有する排水を活性汚泥処理で脱窒ならびに脱硝を行うに当たり、ｐＨ低下や脱窒による汚泥の浮上などの問題がある。
【０００９】
本発明は、このような問題に対処するためになされたもので、高濃度の窒素成分やリン成分、有機物質などの汚濁物質が含まれている排水の活性汚泥処理を効率的に行うことのできる微生物反応槽およびそれを用いた排水処理方法を提供することを目的とする。
【００１０】
【課題を解決するための手段】
本発明の微生物反応槽は、窒素含有汚濁物質を含有する原水の硝化反応および脱窒反応を行う内槽と、この内槽上部に設けられた循環率制御装置と、上記内槽の外側に設けられた円筒状制御板と、上記内槽の外側および内側に設けられた処理水質測定装置とを具備してなり、
上記内槽は、原水供給口を該内槽下部に有し脱窒反応を行う脱窒反応部と、この脱窒反応部の上部に連結部を介して空気取入れ口を該連結部の上部に有し硝化反応を行う硝化反応部とを備えてなり、処理水質測定装置により測定される処理水のｐＨ、酸化還元電位および溶存酸素量から選ばれた少なくとも一つの測定値を検出する手段と、検出された測定値に応じて循環率制御装置の制御量および空気取入れ口より吹込まれる空気量から選ばれる少なくとも一つの量を制御することにより、反応槽内の処理水循環率を制御する手段とを備えたことを特徴とする。
ここで、反応槽内の処理水循環率とは、次式で定義される量をいう。
【００１１】
処理水循環率＝内槽上部から排出される処理水量／原水供給量
【００１２】
また、硝化反応部の容積が脱窒反応部の容積より 1〜 10 倍あることを特徴とする。
【００１３】
また、処理水循環率が5〜 20 であることを特徴とする。
【００１４】
本発明の排水処理方法は、少なくとも活性汚泥処理工程を含む処理工程により窒素含有汚濁物質を含有する原水を処理する排水処理方法であって、活性汚泥処理工程が、上述の微生物反応槽を用いて処理する工程であることを特徴とする。
【００１５】
また、窒素含有汚濁物質を含有する原水は少なくともＢＯＤが 800ppm 以上、全窒素量が 40 ppm 以上含有することを特徴とする。
【００１６】
本発明は、循環率制御装置の制御量や空気取入れ口より吹込まれる空気量により循環ポンプを用いることなく、処理水の循環量を大幅に変動させることができる。それにより適切な硝化条件および脱窒条件を容易に設定できる。さらに、所定の傾斜を有する円筒状制御板を組合わせた強制沈降原理により汚泥の固液分離が極めて効率よくなされるので、硝化反応と脱窒反応とを同一槽内で効率よく行うことができる。
【００１７】
また、本発明においては、原水の脱窒反応により遊離するアルカリ分を利用するので水酸化ナトリウムなどのアルカリ成分を極力添加しないでｐＨ低下が起こらないように硝化し、その後、原水の高濃度のＢＯＤ成分を利用した内性脱窒反応を利用して硝化反応で生成した硝酸等を窒素ガスとして大気放出することができる。このため、原水のアンモニア性窒素を窒素ガスに変化し無毒化すると同時に原水のＢＯＤも低下させることができる。
【００１８】
本発明の微生物反応槽は、原水のＢＯＤ負荷が小さいにもかかわらず、窒素分濃度が高い場合は、プロトン供与体などの有機物質からなる脱窒菌栄養物を嫌気性脱窒部に添加して処理することができる。また、この場合、処理水のｐＨが低下しやすいので、アルカリ成分を添加する設備を有している。
【００１９】
【発明の実施の形態】
本発明の微生物反応槽を図１および図２により説明する。図１は微生物反応槽の断面図であり、図２は微生物反応槽の斜視図であり、図２（ａ）は反応槽を図２（ｂ）は攪拌装置をそれぞれ示す。
微生物反応槽１は、内槽２と、この内槽２の上部に設けられた循環率制御装置３と、外側に設けられた円筒状制御板４と、外側および内側に設けられた処理水質測定装置５とから構成されている。
【００２０】
内槽２は、連結部２ｃで連結され、その横断面構造が円状をしている硝化反応部２ａと脱窒反応部２ｂとより構成されている。硝化反応部２ａの容積は脱窒反応部２ｂの容積の 1〜 10 倍であることが好ましい。この範囲であると高濃度窒素含有汚濁物質を含有する原水の硝化反応および脱窒反応を効率よく行うことができる。また、脱窒反応部２ｂの下部には原水供給口６および脱窒菌栄養物供給口７が、硝化反応部２ａの下部より空気取入れ口８およびアルカリ供給口９が設けられている。
【００２１】
脱窒菌栄養物供給口７およびアルカリ供給口９は、ＢＯＤ負荷が小さいにもかかわらず、窒素分濃度が高い原水の処理などに好適である。一方、処理される原水の種類および汚濁の程度等によっては、脱窒菌栄養物供給口７およびアルカリ供給口９を省略することができる。
【００２２】
内槽２内には、攪拌機１０が内設されタービン羽１０ａ、１０ｂおよび１０ｃが設けられている。タービン羽１０ｃは連結部２ｃの位置に配置されている。タービン羽１０ｃの配置により、硝化反応部２ａから脱窒反応部２ｂへの処理水の逆流を防ぐことができる。
【００２３】
この内槽２の外側に円筒状制御板４ａ、４ｂ、４ｃが配置されている。円筒状制御板４ｂおよび４ｃは所定の傾斜を有している。この傾斜は急速強制沈降を可能とする角度に設定されている。
また、処理水質測定装置５ａ、５ｂ、５ｃは、内槽２の内外に設けられている。この処理水質測定装置は、処理水の水素イオン濃度（ｐＨ）、酸化還元電位（ＯＲＰ）、溶存酸素（ＤＯ）を測定する装置である。
なお、１１は浄化された処理水の放流口であり、１２は余剰汚泥引抜き口である。図１において、反応槽下部の斜線部は活性汚泥の沈降層を示す。また、浮上汚泥を脱窒反応部２ｂへ戻すポンプ１３を設けることが好ましい。
【００２４】
微生物反応槽１は、さらに処理水質測定装置により測定される処理水のｐＨ、酸化還元電位および溶存酸素量から選ばれた少なくとも一つの測定値を検出する手段を有している。この手段により検出された検出値に応じて、あらかじめ制御装置のメモリ上に電子的に格納された制御プログラムにより循環率制御装置３の制御量および空気取入れ口８より吹込まれる空気量から選ばれる少なくとも一つの量を制御する。循環率制御装置３の制御量は、具体的には液面調節バルブの開閉、あるいは液面調節板の上下動等によりなされる。
空気量あるいは上記制御量を調節することにより、処理水の循環率をポンプを用いることなく変動させることができる。
処理水は、後述するように、硝化反応部２ａから内槽２の外側に配置された円筒状制御板を経て嫌気状態の脱窒反応部２ｂへ、さらに脱窒反応部２ｂから好気状態の硝化反応部２ａへと循環することにより、脱窒、脱リンが行われる。したがって、処理水の循環率を検出値に応じて所定の制御プログラムに基づき制御することにより、最適な脱窒、脱リンを行うことができる。
【００２５】
内槽を構成する硝化反応部の容積は脱窒反応部の容積より 1〜 10 倍、より好ましくは 4〜 10 倍に設定される。この範囲とすることにより、窒素含有汚濁物質を含有する原水の最適な脱窒、脱リンを行うことができる。特に高濃度窒素含有汚濁物質を含有する原水における脱窒反応と硝化反応とのバランスを保ことができる。
【００２６】
本発明の微生物反応槽内での処理水循環率は、好ましくは 5〜 20 である。処理水循環率が5未満であると、硝化反応がより起こりやすくなり、また、 20 を越えると硝化反応と脱窒反応とのバランスが崩れ、原水の脱窒、脱リンを行うことができなくなる。すなわち、処理水循環率をこの範囲とすることにより、処理水質測定装置により測定される処理水の酸化還元電位を、脱窒反応部において−10mV以下、好ましくは−50mV以下、硝化反応部において＋10mV以上、好ましくは＋100mV 以上に維持することができる。その結果、硝化反応および脱窒反応が十分に行われ、脱窒、脱リンが連続的になされる。なお、このような条件下において硝化反応部でのｐＨは 4.5〜8.5 、好ましくは 5.5〜7.5 の範囲となる。
【００２７】
以下、微生物反応槽１を用いて高濃度窒素含有汚濁物質を含む原水の排水処理方法について説明する。
ウェジワイヤースクリーンなどで固形分が分離された高濃度窒素含有汚濁物質を含む原水は、微生物反応槽１の最下部に連続的に供給される。なお、供給される原水のＢＯＤおよびＳＳ値は、あらかじめ測定しておくことが好ましい。
本発明は、高濃度の窒素含有汚濁物質を含有する原水の排水処理に好適であり、そのような原水としては、たとえばＢＯＤが 800ppm 以上、好ましくは 5,000ppm 以上、より好ましくは 10,000ppm以上、さらにより好ましくは 20,000ppm以上、全窒素量が 40ppm以上、好ましくは 100ppm 以上、より好ましくは 1,000ppm 以上、ＳＳ値が 100ppm 以上、好ましくは 500ppm 以上含有する原水である。また、固形分濃度（ＭＬＳＳ）が 6,000〜 15,000ppm、好ましくは 8,000〜 12,000ppmの範囲を含む原水の処理にも好適である。
【００２８】
微生物反応槽１には活性汚泥が固形分換算で 5,000〜10,000ppm 入れられており、原水は、まず下内槽２ｂ内にて嫌気状態で活性汚泥に接触し、脱窒反応が行われる。次いで空気が吹込まれている上内槽２ａに移り好気状態で活性汚泥に接触し、硝化反応が進行する。硝化反応が進行するにつれ処理液のｐＨ等が低下する。処理液のｐＨ値、酸化還元電位、溶存酸素量が処理水質測定装置５で測定され、これらの値に基づき原水の循環量が定められる。具体的には、酸化還元電位を、硝化反応部において＋10 mV 以上、脱窒反応部において−10 mV 以下に維持できるように空気吹き込み量などを調整して処理水を循環する。循環量は、循環ポンプなどを使用することなく、空気量および／または循環率制御装置を制御することにより容易に行うことができる。このため本発明は省エネルギー型の排水処理方法である。また、本設備は、微生物反応の各ユニットをそれぞれ調整できるので、これらの制御を予めプログラム化し、無人で自動運転することが容易であり、省力化プラントとしての特徴を有している。
【００２９】
また、原水のＢＯＤ負荷が小さいにもかかわらず、窒素分濃度が高い場合は、プロトン供与体などの有機物質からなる脱窒菌栄養物、たとえばメタノールを嫌気性脱窒部に添加して処理することが好ましく、この場合、処理水のｐＨが低下しやすいので、水酸化ナトリウムなどのアルカリ成分を添加することが好ましい。
【００３０】
本発明の排水処理方法は、微生物反応槽を１槽用いてもよいが、また複数槽用いることもできる。この場合、第１槽からの放流水を第２槽の原水供給口に導入する。また、たとえば２つの微生物反応槽を直列で連結する場合は、第２槽における硝化反応部の容積と脱窒反応部の容積との比率を第１槽における比率と変えることにより、より効果的に排水処理を行うことができる。具体的には、容積比を第１槽のそれより小さくすることにより、脱窒・脱リンを行うことができる。
【００３１】
また、本発明の排水処理方法を、従来の排水処理方法と組合わせて行うことができる。たとえば、既設の好気硝化槽と嫌気脱窒槽の連結からなる排水処理設備において、それぞれの槽からの流出液を本発明の微生物反応槽に供給することにより、より効果的に脱窒・脱リンを行うことができる。
【００３２】
【実施例】
実施例１
生ゴミ埋め立て処分場の浸出排水処分場における排水処理を１つの微生物反応槽を用いて行った。原水中のＢＯＤは 23,000ppm、全窒素分は 5,200ppm 、全リン分は 210ppm 、ＳＳ値は 2,200ppm であった。微生物反応槽は、全体の容積が 5 m³、内槽硝化部の容積が 2 m³、脱窒部の容積が 0.3 m³である。この微生物反応槽全容積に対して固形分換算で 4,000ppm の活性汚泥を投入して原水の処理をした。
【００３３】
原水を0.5m³／日の割合で微生物反応槽に供給した。また、循環率が 8となるように空気量および循環率制御装置を調節した。その時の嫌気脱窒部でのｐＨは 7.1、酸化還元電位は−250mV 、溶存酸素量は 0、好気硝化部でのｐＨは 6.1、酸化還元電位は＋210mV 、溶存酸素量は 0.8ppm であった。微生物反応槽にて処理された放流水のＢＯＤは 18ppm、全窒素分は 13ppm、ＳＳ値は 2ppm 、全リン分は 1.5 ppmであった。なお、余剰汚泥は、余剰汚泥引抜き口より逐次引き抜いた。また、排水処理は自動運転で行った。
【００３４】
実施例２
ゴミ埋め立て処分場の排水処理を実施例１と同一の 2つの微生物反応槽を連結して行った。ただし第１槽目の好気硝化部の容積は 1.3 m³、嫌気脱窒部の容積は 0.6 m³とした。原水中のＢＯＤは 5,000ppm 、全窒素分は 4,000ppm 、全リン分は 160ppm 、ＳＳ値は 2,000ppm であった。活性汚泥を投入量は実施例１と同一である。
原水を 1.5 m³／日の割合で微生物反応槽に供給した。また、循環率が 6となるように空気量および循環率制御装置を調節した。
【００３５】
第１微生物反応槽からの放流水のＢＯＤは 35ppm、全窒素分は 400ppm 、ＳＳ値は 50ppmであった。次いで、この放流水を第２微生物反応槽の原水供給口に導入して、排水処理を行った。なお、第２微生物反応槽の脱窒反応部において酸化還元電位が−80mV以下となるように、メタノールを添加した。
【００３６】
第２微生物反応槽にて処理された放流水のＢＯＤは 12ppm、全窒素分は 13ppm、ＳＳ値は 10ppm、全リン分は 1ppm であった。
【００３７】
実施例３
し尿処理場からの排水処理を２つの微生物反応槽を連結して行った。原水は、生し尿 60 重量％および浄化槽汚泥 40 重量％からなる排水で、原水中のＢＯＤは 9,000ppm 、全窒素分は 4,500ppm 、ＳＳ値は 4,200ppm であった。
【００３８】
第１微生物反応槽は、全体の容積が 4.5 m³、内槽硝化部の容積が 1.3 m³、脱窒部の容積が 0.6 m³で、第２微生物反応槽は、全体の容積が 2 m³、内槽硝化部の容積が 0.8 m³、脱窒部の容積が 0.3 m³である。この微生物反応槽全容積に対して固形分換算で 3,500ppm 、3,000ppmのそれぞれ予め馴養した活性汚泥をそれぞれ投入して原水の処理をした。
【００３９】
原水を 0.8 m³／日の割合で微生物反応槽に供給した。循環率は第１微生物反応槽で 11 、第２微生物反応槽で 5となるように空気量および循環率制御装置を調節した。また、第２微生物反応槽の脱窒反応部において酸化還元電位が−50mV以下となるように、メタノールを添加した。
第２微生物反応槽にて処理された放流水のＢＯＤは 8ppm 、全窒素分は 2ppm 、ＳＳ値は 7ppm 、全リン分は 1ppm であった。
【００４０】
実施例４
し尿処理場または排水処分場における既設の排水処理設備を本発明の微生物反応槽を用いて改善する場合の例である。
既設の排水処理は、ばっ気槽が 60m³×6 室で、最終沈澱池が直径 6m 、深さ 3.5m の槽が 2池ある排水処理設備で、嫌気好気処理をしている。しかし、汚濁負荷が増加し、硝化脱窒が不十分となり処理水の水質が確保できなくなる場合も生じる、またばっ気を強めるとｐＨが低下し、溶存酸素量を上昇させられないので、最終沈澱池の 1池を本発明の微生物反応槽に代えた。用いた微生物反応槽は、全体の容積が 160 m³、内槽硝化部の容積が 55m³、脱窒部の容積が 20m³である。
既設の処理槽を嫌気、好気、好気、嫌気、好気、好気の順に配列し、その後に沈澱処理池と、最後に本発明の微生物反応槽を配置した排水処理設備とした。
【００４１】
この排水処理設備を用いて、実施例３と同一の原水を処理した。なお、微生物反応槽における好気硝化部での酸化還元電位は＋150mV 、嫌気脱窒部での酸化還元電位は−120mV となるようにメタノールを添加した。また、微生物反応槽から引き抜かれる余剰汚泥は、既設の最初の嫌気脱窒槽に戻した。改善前後の処理水量および水質特性について表１に示す。
【００４２】
【表１】

【００４３】
表１に示すように、本発明の微生物反応槽を用いて既設の排水処理設備を改善することにより、排水処理量も増加させることができ、また水質も向上する。
【００４４】
【発明の効果】
本発明の微生物反応槽は、脱窒反応部と硝化反応部とを備えた内槽と、この内槽の外側に円筒状制御板と、処理水質を検出し、反応槽内の処理水循環率を制御する手段とを備えているので、循環ポンプを用いることなく処理水の循環量を大幅に変動させることができ、適切な硝化条件および脱窒条件を容易に設定できる。また強制沈降原理により汚泥の固液分離が極めて効率よくなされるため、循環率を上げても固液分離が容易である。その結果、単一の反応槽で、かつ少ないエネルギー消費量で高濃度の窒素含有汚濁物質を含有する原水を処理することができる。
【００４５】
また、硝化反応部の容積が脱窒反応部の容積より 1〜 10 倍あるので、脱窒反応および硝化反応をバランスよく行うことができる。
【００４６】
また、処理水循環率が5〜 20 であるので、硝化反応および脱窒反応が十分に行われ、脱窒、脱リンを連続的に行うことができる。
【００４７】
本発明の排水処理方法は、上述の微生物反応槽を用いて処理する工程を有するので、省エネルギーで、かつコンパクトな装置で高濃度の窒素含有汚濁物質を含有する原水を自動運転で処理することができる。
【図面の簡単な説明】
【図１】微生物反応槽の断面図である。
【図２】微生物反応槽の斜視図である。
【図３】修正バーナード法のフロー図である。
【符号の説明】
１微生物反応槽
２内槽
３循環率制御装置
４円筒状制御板
５処理水質測定装置
６原水供給口
７脱窒菌栄養物供給口
８空気取入れ口
９アルカリ供給口
１０攪拌機
１１放流口
１２余剰汚泥引抜き口
１３ポンプ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a microbial reaction tank and a wastewater treatment method.
[0002]
[Prior art]
Wastewater that flows out of human waste treatment plants and garbage treatment plants contains high-concentration nitrogen, phosphorus, and organic pollutants that increase BOD and SS values, causing environmental pollution such as river pollution and red tide. It has become.
Conventionally, a so-called modified Bernard method, which is one of aerobic and anaerobic circulation methods, is known as a method for treating wastewater containing such high-concentration pollutants. An example of the modified Bernard method is shown in FIG. FIG. 3 is a flow chart of the modified Bernard method. This method uses the first denitrification tank 14a located before and after the first nitrification tank 15a and the first denitrification tank 15a in the activated sludge treatment process in order to reuse the alkali liberated during the denitrification reaction in the nitrification reaction. The second denitrification tank 14b is divided into two stages, a second nitrification tank 15b is provided after the second denitrification tank 14b, and the mixed liquid flowing out from the first and second nitrification tanks is circulated to the first denitrification tank. .
[0003]
[Problems to be solved by the invention]
However, wastewater discharged from human waste treatment plants and garbage treatment plants contains high concentrations of nitrogen components that are 10 to 100 times higher than normal wastewater, and pollutants such as phosphorus components and organic substances are also contained in high concentrations. Therefore, the wastewater treatment has the following problems.
[0004]
First, since high concentration ammoniacal nitrogen itself has bactericidal properties, it often inhibits the activity of activated sludge in the activated sludge treatment process. For this reason, there is a problem that the activated sludge treatment becomes insufficient.
[0005]
Secondly, in the so-called modified Bernard method or the like, the pH decreases as the nitrification reaction proceeds in the nitrification tank, but the nitrification reaction depends on the pH, so the nitrification reaction slows down as the pH decreases. As a result, there is still a problem that the activated sludge treatment becomes insufficient. If the activated sludge treatment becomes insufficient, there is a problem that phosphorus removal and the like are also insufficient.
[0006]
Third, if activated sludge treatment is insufficient and the denitrification reaction is slow, the residual ammonia, nitrate ion, nitrite ion concentration, etc. will increase, resulting in high BOD depending on these nitrogen compounds, and insufficient wastewater treatment. There is a problem of becoming.
[0007]
Fourth, high-concentration pollutant-containing wastewater requires high-concentration activated sludge, which inevitably tends to increase the solid content concentration (MLSS) and the like. Therefore, it is difficult to supply oxygen, and it becomes difficult to stir the activated sludge and it is difficult to separate the solid and the liquid in the precipitation tank.
[0008]
Fifth, in spite of low organic pollutant concentration, there are problems such as pH reduction and sludge levitation due to denitrification when denitrifying and denitrating wastewater having a high nitrogen component by activated sludge treatment.
[0009]
The present invention has been made to cope with such a problem, and it is possible to efficiently perform an activated sludge treatment of wastewater containing pollutants such as a high concentration of nitrogen, phosphorus and organic substances. An object of the present invention is to provide a microbial reaction tank that can be used and a wastewater treatment method using the same.
[0010]
[Means for Solving the Problems]
The microorganism reaction tank of the present invention is provided in an inner tank for performing nitrification reaction and denitrification reaction of raw water containing a nitrogen-containing pollutant, a circulation rate control device provided in the upper part of the inner tank, and provided outside the inner tank. And a treated water quality measuring device provided outside and inside the inner tank,
The inner tank has a raw water supply port at the lower part of the inner tank and performs a denitrification reaction part, and an air intake port at the upper part of the connection part at the upper part of the denitrification reaction part. A means for detecting at least one measured value selected from the pH of the treated water, the oxidation-reduction potential, and the amount of dissolved oxygen measured by the treated water quality measuring device. Means for controlling the treatment water circulation rate in the reaction tank by controlling at least one amount selected from the control amount of the circulation rate control device and the amount of air blown from the air intake according to the detected measurement value; It is provided with.
Here, the treated water circulation rate in the reaction tank refers to an amount defined by the following equation.
[0011]
Treatment water circulation rate = amount of treated water discharged from the upper part of the inner tank / raw water supply amount [0012]
Further, the volume of the nitrification reaction part is 1 to 10 times that of the denitrification reaction part.
[0013]
The treated water circulation rate is 5 to 20.
[0014]
The wastewater treatment method of the present invention is a wastewater treatment method for treating raw water containing nitrogen-containing pollutants by a treatment step including at least an activated sludge treatment step, wherein the activated sludge treatment step uses the above-described microorganism reaction tank. It is a process to process.
[0015]
In addition, raw water containing nitrogen-containing pollutants contains at least BOD of 800 ppm or more and total nitrogen content of 40 ppm or more.
[0016]
According to the present invention, the circulation amount of the treated water can be varied greatly without using a circulation pump depending on the control amount of the circulation rate control device and the amount of air blown from the air intake port. Thereby, appropriate nitrification conditions and denitrification conditions can be set easily. Furthermore, since the solid-liquid separation of sludge is performed very efficiently by the forced sedimentation principle combined with a cylindrical control plate having a predetermined inclination, the nitrification reaction and the denitrification reaction can be performed efficiently in the same tank. .
[0017]
Further, in the present invention, since the alkali content liberated by the denitrification reaction of the raw water is used, nitrification is performed so as not to cause a pH drop without adding an alkali component such as sodium hydroxide as much as possible. Nitric acid or the like produced by nitrification using an internal denitrification reaction using a BOD component can be released into the atmosphere as nitrogen gas. For this reason, the ammonia nitrogen of the raw water is changed to nitrogen gas and detoxified, and at the same time the BOD of the raw water can be reduced.
[0018]
In the microbial reaction tank of the present invention, in the case where the BOD load of the raw water is small but the nitrogen concentration is high, denitrifying nutrients made of organic substances such as proton donors are added to the anaerobic denitrifying section. Can be processed. Further, in this case, since the pH of the treated water is likely to be lowered, a facility for adding an alkali component is provided.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The microbial reaction tank of the present invention will be described with reference to FIGS. 1 is a cross-sectional view of a microbial reaction tank, FIG. 2 is a perspective view of the microbial reaction tank, FIG. 2 (a) shows a reaction tank, and FIG. 2 (b) shows a stirring device.
The microbial reaction tank 1 includes an inner tank 2, a circulation rate control device 3 provided on the upper part of the inner tank 2, a cylindrical control plate 4 provided on the outside, and a treatment water quality measurement provided on the outside and inside. The apparatus 5 is comprised.
[0020]
The inner tank 2 is constituted by a nitrification reaction part 2a and a denitrification reaction part 2b which are connected by a connection part 2c and whose cross-sectional structure is circular. The volume of the nitrification reaction part 2a is preferably 1 to 10 times the volume of the denitrification reaction part 2b. Within this range, nitrification and denitrification of raw water containing high-concentration nitrogen-containing pollutants can be efficiently performed. Further, a raw water supply port 6 and a denitrifying nutrient supply port 7 are provided at the lower part of the denitrification reaction unit 2b, and an air intake port 8 and an alkali supply port 9 are provided from the lower part of the nitrification reaction unit 2a.
[0021]
The denitrifying nutrient supply port 7 and the alkali supply port 9 are suitable for the treatment of raw water having a high nitrogen content despite a small BOD load. On the other hand, the denitrifying bacteria nutrient supply port 7 and the alkali supply port 9 can be omitted depending on the type of raw water to be treated and the degree of contamination.
[0022]
In the inner tank 2, a stirrer 10 is installed, and

turbine blades

10a, 10b and 10c are provided. The turbine blade 10c is disposed at the position of the connecting portion 2c. By arranging the turbine blade 10c, it is possible to prevent the backflow of the treated water from the nitrification reaction section 2a to the denitrification reaction section 2b.
[0023]

Cylindrical control plates

4a, 4b, and 4c are disposed outside the inner tank 2.

Cylindrical control plates

4b and 4c have a predetermined inclination. This inclination is set to an angle that enables rapid forced settling.
The treated water

quality measuring devices

5a, 5b, and 5c are provided inside and outside the inner tank 2. This treated water quality measuring device is a device that measures the hydrogen ion concentration (pH), redox potential (ORP), and dissolved oxygen (DO) of treated water.
In addition, 11 is an outlet for purified treated water, and 12 is an excess sludge outlet. In FIG. 1, the hatched portion at the bottom of the reaction tank indicates the sedimentation layer of activated sludge. Moreover, it is preferable to provide a pump 13 for returning the floating sludge to the denitrification reaction section 2b.
[0024]
The microbial reaction tank 1 further has means for detecting at least one measured value selected from the pH of the treated water, the oxidation-reduction potential, and the amount of dissolved oxygen measured by the treated water quality measuring device. In accordance with the detected value detected by this means, the control program stored in advance in the memory of the control device is selected from the control amount of the circulation rate control device 3 and the amount of air blown from the air intake 8. Control at least one amount. Specifically, the control amount of the circulation rate control device 3 is determined by opening / closing the liquid level control valve or moving the liquid level control plate up and down.
By adjusting the air amount or the control amount, the circulation rate of the treated water can be changed without using a pump.
As will be described later, the treated water passes from the nitrification reaction part 2a to the denitrification reaction part 2b in an anaerobic state through a cylindrical control plate disposed outside the inner tank 2, and further from the denitrification reaction part 2b to the aerobic state. By decirculating to the nitrification reaction part 2a, denitrification and dephosphorization are performed. Therefore, optimal denitrification and dephosphorization can be performed by controlling the circulation rate of the treated water based on the detection value based on a predetermined control program.
[0025]
The volume of the nitrification reaction part constituting the inner tank is set to 1 to 10 times, more preferably 4 to 10 times the volume of the denitrification reaction part. By setting it as this range, the optimal denitrification and dephosphorization of the raw water containing a nitrogen-containing pollutant can be performed. In particular, the balance between the denitrification reaction and the nitrification reaction in the raw water containing the high-concentration nitrogen-containing pollutant can be maintained.
[0026]
The treatment water circulation rate in the microbial reaction tank of the present invention is preferably 5 to 20. If the treated water circulation rate is less than 5 , the nitrification reaction is more likely to occur, and if it exceeds 20, the balance between the nitrification reaction and the denitrification reaction is lost, and denitrification and dephosphorization of the raw water cannot be performed. That is, by setting the treatment water circulation rate within this range, the oxidation-reduction potential of the treated water measured by the treated water quality measuring device is −10 mV or less, preferably −50 mV or less in the denitrification reaction unit, and +10 mV or more in the nitrification reaction unit. Preferably, it can be maintained at +100 mV or more. As a result, the nitrification reaction and the denitrification reaction are sufficiently performed, and denitrification and dephosphorization are continuously performed. Under such conditions, the pH in the nitrification reaction zone is 4.5 to 8.5, preferably 5.5 to 7.5.
[0027]
Hereinafter, the wastewater treatment method for raw water containing high-concentration nitrogen-containing pollutant using the microbial reaction tank 1 will be described.
The raw water containing the high-concentration nitrogen-containing pollutant whose solid content has been separated by a wedge wire screen or the like is continuously supplied to the lowermost part of the microorganism reaction tank 1. In addition, it is preferable to measure in advance the BOD and SS value of the supplied raw water.
The present invention is suitable for wastewater treatment of raw water containing a high concentration of nitrogen-containing pollutants, and as such raw water, for example, BOD is 800 ppm or more, preferably 5,000 ppm or more, more preferably 10,000 ppm or more, Raw water containing 20,000 ppm or more, total nitrogen content of 40 ppm or more, preferably 100 ppm or more, more preferably 1,000 ppm or more, and SS value of 100 ppm or more, preferably 500 ppm or more. It is also suitable for treatment of raw water having a solid content concentration (MLSS) in the range of 6,000 to 15,000 ppm, preferably 8,000 to 12,000 ppm.
[0028]
The microbial reaction tank 1 contains 5,000 to 10,000 ppm of activated sludge in terms of solid content, and the raw water first comes into contact with the activated sludge in an anaerobic state in the lower inner tank 2b to perform a denitrification reaction. Next, it moves to the upper inner tank 2a where air is blown, contacts the activated sludge in an aerobic state, and the nitrification reaction proceeds. As the nitrification reaction proceeds, the pH of the treatment solution decreases. The pH value of the treatment liquid, the oxidation-reduction potential, and the dissolved oxygen amount are measured by the treatment water quality measuring device 5, and the circulation amount of the raw water is determined based on these values. Specifically, the treated water is circulated by adjusting the air blowing amount so that the oxidation-reduction potential can be maintained at +10 mV or more in the nitrification reaction section and −10 mV or less in the denitrification reaction section. The circulation amount can be easily achieved by controlling the air amount and / or the circulation rate control device without using a circulation pump or the like. Therefore, the present invention is an energy-saving wastewater treatment method. In addition, since this unit can adjust each unit of the microbial reaction, it is easy to program these controls in advance and automatically operate unattended, and has a feature as a labor-saving plant.
[0029]
In addition, if the nitrogen content is high even though the BOD load of raw water is low, denitrifying bacteria nutrients made of organic substances such as proton donors, such as methanol, should be added to the anaerobic denitrification section. In this case, since the pH of the treated water tends to decrease, it is preferable to add an alkali component such as sodium hydroxide.
[0030]
In the wastewater treatment method of the present invention, one microbial reaction tank may be used, or a plurality of tanks may be used. In this case, the discharged water from the first tank is introduced into the raw water supply port of the second tank. For example, when two microbial reaction tanks are connected in series, the ratio of the volume of the nitrification reaction part and the volume of the denitrification reaction part in the second tank can be changed more effectively by changing the ratio in the first tank. Waste water treatment can be performed. Specifically, denitrification and dephosphorization can be performed by making the volume ratio smaller than that of the first tank.
[0031]
Moreover, the waste water treatment method of the present invention can be performed in combination with a conventional waste water treatment method. For example, in a wastewater treatment facility consisting of an existing aerobic nitrification tank and an anaerobic denitrification tank, by supplying the effluent from each tank to the microbial reaction tank of the present invention, denitrification / dephosphorization can be carried out more effectively. It can be performed.
[0032]
【Example】
Example 1
Wastewater treatment at the leachate wastewater disposal site of the garbage landfill disposal site was performed using one microbial reaction tank. The BOD in the raw water was 23,000 ppm, the total nitrogen content was 5,200 ppm, the total phosphorus content was 210 ppm, and the SS value was 2,200 ppm. The total volume of the microbial reactor is 5 m ³ , the volume of the inner tank nitrification part is 2 m ³ , and the volume of the denitrification part is 0.3 m ³ . Raw water was treated by adding 4,000 ppm of activated sludge in terms of solid content to the total volume of the microbial reactor.
[0033]
Raw water was supplied to the microbial reactor at a rate of 0.5 m ³ / day. In addition, the air volume and the circulation rate control device were adjusted so that the circulation rate was 8. At that time, the pH in the anaerobic denitrification part was 7.1, the oxidation-reduction potential was −250 mV, the dissolved oxygen amount was 0, the pH in the aerobic nitrification part was 6.1, the oxidation-reduction potential was +210 mV, and the dissolved oxygen amount was 0.8 ppm. . The BOD of the effluent treated in the microbial reactor was 18 ppm, the total nitrogen content was 13 ppm, the SS value was 2 ppm, and the total phosphorus content was 1.5 ppm. Excess sludge was sequentially extracted from the excess sludge extraction port. In addition, wastewater treatment was performed automatically.
[0034]
Example 2
Wastewater treatment at the landfill site was performed by connecting the same two microbial reaction tanks as in Example 1. However, the volume of the aerobic nitrification section in the first tank was 1.3 m ³ and the volume of the anaerobic denitrification section was 0.6 m ³ . The BOD in the raw water was 5,000 ppm, the total nitrogen content was 4,000 ppm, the total phosphorus content was 160 ppm, and the SS value was 2,000 ppm. The amount of activated sludge charged is the same as in Example 1.
Raw water was supplied to the microbial reactor at a rate of 1.5 m ³ / day. In addition, the air volume and the circulation rate control device were adjusted so that the circulation rate was 6.
[0035]
The BOD of the effluent from the first microbial reactor was 35 ppm, the total nitrogen content was 400 ppm, and the SS value was 50 ppm. Subsequently, the discharged water was introduced into the raw water supply port of the second microbial reaction tank to perform wastewater treatment. In addition, methanol was added so that the oxidation-reduction potential was −80 mV or less in the denitrification reaction part of the second microorganism reaction tank.
[0036]
The BOD of the effluent treated in the second microbial reactor was 12 ppm, the total nitrogen content was 13 ppm, the SS value was 10 ppm, and the total phosphorus content was 1 ppm.
[0037]
Example 3
Waste water treatment from the human waste treatment plant was performed by connecting two microbial reaction tanks. The raw water was a wastewater consisting of 60% by weight of raw urine and 40% by weight of septic tank sludge. The BOD in the raw water was 9,000ppm, the total nitrogen content was 4,500ppm, and the SS value was 4,200ppm.
[0038]
The first microbial reaction tank has an overall volume of 4.5 m ³ , the inner tank nitrification part has a volume of 1.3 m ³ , the denitrification part has a volume of 0.6 m ³ , and the second microbial reaction tank has an overall volume of 2 m ^3. The volume of the inner tank nitrification part is 0.8 m ³ , and the volume of the denitrification part is 0.3 m ³ . The raw water was treated by adding 3,500 ppm and 3,000 ppm of activated sludge conditioned in advance to the total volume of the microbial reactor, respectively.
[0039]
Raw water was supplied to the microbial reactor at a rate of 0.8 m ³ / day. The air amount and the circulation rate control device were adjusted so that the circulation rate was 11 in the first microorganism reaction tank and 5 in the second microorganism reaction tank. Further, methanol was added so that the oxidation-reduction potential was −50 mV or less in the denitrification reaction part of the second microorganism reaction tank.
The BOD of the discharged water treated in the second microbial reactor was 8 ppm, the total nitrogen content was 2 ppm, the SS value was 7 ppm, and the total phosphorus content was 1 ppm.
[0040]
Example 4
It is an example in the case of improving the existing wastewater treatment facility in a human waste treatment plant or a wastewater disposal plant using the microorganism reaction tank of the present invention.
The existing wastewater treatment is anaerobic and aerobic treatment with a wastewater treatment facility with an aeration tank of 60m ³ × 6 rooms, a final sedimentation tank of 6m in diameter, and two tanks with a depth of 3.5m. However, the pollution load increases and nitrification / denitrification may be insufficient, and the quality of the treated water may not be ensured. In addition, if aeration is strengthened, the pH will decrease and the amount of dissolved oxygen cannot be increased. One of the ponds was replaced with the microbial reactor of the present invention. The total volume of the microbial reaction tank used was 160 m ³ , the volume of the inner tank nitrification section was 55 m ³ , and the volume of the denitrification section was 20 m ³ .
The existing treatment tanks were arranged in the order of anaerobic, aerobic, aerobic, anaerobic, aerobic, and aerobic, followed by a wastewater treatment facility in which the sedimentation pond and finally the microbial reaction tank of the present invention were arranged.
[0041]
The same raw water as in Example 3 was treated using this waste water treatment facility. Methanol was added so that the oxidation-reduction potential in the aerobic nitrification part in the microorganism reaction tank was +150 mV, and the oxidation-reduction potential in the anaerobic denitrification part was -120 mV. Moreover, the excess sludge withdrawn from the microbial reaction tank was returned to the existing first anaerobic denitrification tank. The amount of treated water and water quality characteristics before and after improvement are shown in Table 1.
[0042]
[Table 1]

[0043]
As shown in Table 1, by improving the existing wastewater treatment facility using the microorganism reaction tank of the present invention, the wastewater treatment amount can be increased and the water quality is also improved.
[0044]
【The invention's effect】
The microbial reaction tank of the present invention has an inner tank equipped with a denitrification reaction part and a nitrification reaction part, a cylindrical control plate on the outside of the inner tank, and the quality of the treated water, and the treated water circulation rate in the reaction tank is determined. Therefore, the amount of treated water circulated can be varied greatly without using a circulation pump, and appropriate nitrification conditions and denitrification conditions can be easily set. In addition, solid-liquid separation of sludge is very efficiently performed by the forced sedimentation principle, so that solid-liquid separation is easy even if the circulation rate is increased. As a result, it is possible to treat raw water containing a high concentration of nitrogen-containing pollutant in a single reaction tank and with low energy consumption.
[0045]
Moreover, since the volume of the nitrification reaction part is 1 to 10 times that of the denitrification reaction part, the denitrification reaction and the nitrification reaction can be performed in a well-balanced manner.
[0046]
Further, since the treatment water circulation rate is 5 to 20, the nitrification reaction and the denitrification reaction are sufficiently performed, and the denitrification and dephosphorization can be performed continuously.
[0047]
Since the wastewater treatment method of the present invention has a step of treating using the above-described microbial reaction tank, it is possible to treat raw water containing high-concentration nitrogen-containing pollutants with automatic operation with an energy-saving and compact device. it can.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a microbial reaction tank.
FIG. 2 is a perspective view of a microorganism reaction tank.
FIG. 3 is a flow diagram of the modified Bernard method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Microbial reaction tank 2 Inner tank 3 Circulation rate control apparatus 4 Cylindrical control board 5 Treated water quality measurement apparatus 6 Raw water supply port 7 Denitrification bacteria nutrient supply port 8 Air intake port 9 Alkali supply port 10 Stirrer 11 Outlet port 12 Excess sludge extraction Mouth 13 pump

Claims

At least BOD more than 800 ppm, and the inner tub in which the total amount of nitrogen to perform nitrification and denitrification of the raw water containing more than 40 ppm, a circulation rate control device provided in the inner tank top, along the outer surface of the inner tub A microbial reaction tank comprising a cylindrical control plate for forcibly settling sludge provided and a treated water quality measuring device provided outside and inside the inner tank,
The inner tank has a raw water supply port at the lower part of the inner tank and performs the denitrification reaction, and an upper part of the denitrification reaction part has an air intake port at the upper part of the connection part. And a nitrification reaction section for performing the nitrification reaction, wherein a cross-sectional structure of the denitrification reaction section and the nitrification reaction section is circular, and a volume of the nitrification reaction section is equal to that of the denitrification reaction section. 1 to 10 times the volume, and a turbine blade is installed in the connecting part between the nitrification reaction part and the denitrification reaction part,
Means for detecting at least one measurement value selected from the pH, redox potential and dissolved oxygen content of the treated water measured by the treated water quality measuring device;
The treated water circulation rate in the reaction vessel is controlled by controlling at least one amount selected from the control amount of the circulation rate control device and the amount of air blown from the air intake according to the detected measurement value. And a circulating rate of the treated water is 5 to 20, and circulates through a sedimentation layer of activated sludge settled in the lower part of the reaction tank.

A wastewater treatment method for treating raw water containing nitrogen-containing pollutant containing at least BOD of 800 ppm or more and total nitrogen content of 40 ppm or more by a treatment process including at least an activated sludge treatment process,
The said activated sludge process process is a process processed using the microorganisms reaction tank of Claim 1, The wastewater treatment method characterized by the above-mentioned.

A wastewater treatment method for treating raw water containing nitrogen-containing pollutants by a treatment process including at least an activated sludge treatment process,
The activated sludge treatment step is a step of connecting and treating the microbial reaction tank according to claim 1, introducing raw water into a raw water supply port of the first microbial reaction tank, and discharging water from the first microbial reaction tank. Is introduced into the raw water supply port of the second microorganism reaction tank.

A wastewater treatment method for treating raw water containing nitrogen-containing pollutants by a treatment process including at least an activated sludge treatment process by improving an existing wastewater treatment facility at a human waste treatment plant or a wastewater treatment plant,
A wastewater treatment method, wherein the activated sludge treatment is performed by replacing at least one final sedimentation basin in the existing wastewater treatment facility with the microorganism reaction tank according to claim 1.