JP2004167328A

JP2004167328A - Waste water treatment method

Info

Publication number: JP2004167328A
Application number: JP2002334462A
Authority: JP
Inventors: Seiji Fujino; 清治藤野
Original assignee: NIPPON ARUSHII KK
Current assignee: NIPPON ARUSHII KK
Priority date: 2002-11-19
Filing date: 2002-11-19
Publication date: 2004-06-17
Anticipated expiration: 2022-11-19
Also published as: JP4142410B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste water treatment method which improves waste water treatment capability since activated sludge microbial cells are stabilized even when a concentrated waste water and dilute drain are treated and which makes the microbial cells easily acclimatizable even for the concentrated waste liquid containing much hardly decomposable pollutant. <P>SOLUTION: The waste water treatment method for treating the concentrated waste liquid and the dilute drain is provided with an activated sludge treatment apparatus (AR) for treating the concentrated waste liquid (A) and an activated sludge treatment apparatus (BR) for treating the dilute drain (B). The drain treatment method comprises a step of subjecting the concentrated waste liquid to an anaerobic/aerobic treatment in the apparatus (AR) and a step of subjecting the concentrated waste liquid after the anaerobic/aerobic treatment to the anaerobic/aerobic treatment together with the dilute drain in the apparatus (BR) without subjecting the concentrated waste liquid to solid-liquid separation treatment. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は排水処理方法に関し、特に濃厚廃液と希薄排水とを処理する排水処理方法に関する。
【０００２】
【従来の技術】
生産現場、公共施設等で排出される排水の中には特定の汚濁物質の濃度が高い濃厚廃液と、雑排水と称する比較的汚濁物質の濃度が低い希薄排水とが混在している場合が多い。
従来、活性汚泥法による排水処理設備を用いてこれらの排水を処理する場合、濃厚廃液と希薄排水とを直接、あるいは濃厚廃液に対して嫌気性処理などを実施し、その後活性汚泥に対して汚濁物質が一定の負荷になるように濃厚廃液と希薄排水とを混合して処理している。
また、活性汚泥槽に流入する排水の水質変動により活性汚泥の排水処理能力が低下したとき、水質変動によって菌数が激減した汚泥中細菌を、活性汚泥槽の外で完全栄養培地を用いる個別培養により速やかに増殖させ、それを活性汚泥槽に投入することにより馴養に要する日数を短縮するために、あらかじめ、良好な排水処理能力を示している活性汚泥槽から活性汚泥を採取し、採取された活性汚泥から有機物分解に関与している細菌多数を分離し、それらの細菌の特性を確認して保存しておく排水処理方法が知られている（特許文献１参照）。
【０００３】
【特許文献１】
特開平６−２７７６８６号公報（特許請求の範囲）
【０００４】
【発明が解決しようとする課題】
しかしながら、濃厚廃液と希薄排水とを直接混合すると、水質変動が大きくなり、活性汚泥処理の能力が低下するという問題がある。
また、濃厚廃液を嫌気性処理すると、硫化水素ガスやアンモニアガスが多量に生成しやすくなり、このため、嫌気処理後の濃厚廃液を希薄排水に混合すると、バルキング現象や活性汚泥の解体等が発生する頻度が多くなり、排水処理が不安定になるという問題がある。
また、活性汚泥槽の外で完全栄養培地を用いる個別培養により速やかに増殖させた菌体を用いても、濃厚廃液、あるいは希薄排水の種類が多くなると馴養に要する日数を短縮することが困難になるという問題がある。
【０００５】
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、濃厚廃液と希薄排水とを処理する場合であっても活性汚泥菌体が安定化されるため排水処理能力が向上し、また難分解性の汚濁物質が多い濃厚廃液であっても活性汚泥菌体が馴養されやすい排水処理方法の提供を目的とする。
【０００６】
【課題を解決するための手段】
請求項１に係る発明は、濃厚廃液と希薄排水とを処理する排水処理方法において、濃厚廃液を処理する活性汚泥処理装置（ＡＲ）と、希薄排水を処理する活性汚泥処理装置（ＢＲ）とをそれぞれ設け、濃厚廃液を前記活性汚泥処理装置（ＡＲ）において嫌気・好気処理をする工程と、該嫌気・好気処理後の濃厚廃液を固液分離することなく活性汚泥処理装置（ＢＲ）において希薄排水とともに嫌気・好気処理をする工程とを含むことを特徴とする。
請求項２に係る発明は、請求項１に係る排水処理方法において、活性汚泥処理装置（ＢＲ）における嫌気・好気処理後、活性汚泥を分離して、活性汚泥処理装置（ＡＲ）に戻すか、または活性汚泥処理装置（ＡＲ）と活性汚泥処理装置（ＢＲ）との両方の活性汚泥処理装置に戻す工程を有することを特徴とする。
【０００７】
請求項３に係る発明は、濃厚廃液と希薄排水とを処理する排水処理方法において、濃厚廃液を処理する活性汚泥処理装置（ＡＲ）と、希薄排水を処理する活性汚泥処理装置（ＢＲ）とをそれぞれ設け、濃厚廃液を活性汚泥処理装置（ＡＲ）において嫌気・好気処理をする工程と、該嫌気・好気処理後、活性汚泥を分離して、活性汚泥処理装置（ＡＲ）に戻すか、活性汚泥処理装置（ＢＲ）に戻すか、または活性汚泥処理装置（ＡＲ）と活性汚泥処理装置（ＢＲ）との両方の活性汚泥処理装置に戻すとともに、活性汚泥を分離した液を活性汚泥処理装置（ＢＲ）に戻す工程とを含むことを特徴とする。
【０００８】
請求項４に係る発明は、請求項１または請求項３に係る排水処理方法において、活性汚泥処理装置（ＡＲ）における嫌気・好気処理条件が、嫌気処理時間を０．５〜６時間、好気処理時間を１〜１０時間の範囲で、嫌気・好気処理を１回または複数回行なうことを特徴とする。
請求項５に係る発明は、請求項１または請求項３に係る排水処理方法において、活性汚泥処理装置（ＢＲ）における嫌気・好気処理条件は、嫌気処理時間が０．５〜６時間、好気処理時間が１〜１０時間の範囲で、嫌気・好気処理の循環率を希薄排水の２〜２０倍で行なうことを特徴とする。
【０００９】
濃厚廃液を活性汚泥処理装置（ＡＲ）において嫌気・好気処理をする工程と、該嫌気・好気処理後の濃厚廃液を固液分離することなく活性汚泥処理装置（ＢＲ）において希薄希薄排水とともに嫌気・好気処理をする工程とを組み合わせることにより、嫌気性活性汚泥菌体および好気性活性汚泥菌体のそれぞれの増殖過程と栄養代謝過程とが組み合わされて、嫌気性活性汚泥菌体および好気性活性汚泥菌体の増殖が最大となる。
すなわち、嫌気処理工程では、好気性活性汚泥菌体が分泌した高分子多糖類を分解し、好気処理工程では、嫌気性活性汚泥菌体を消化して汚泥減容化と好気性活性汚泥菌体の増殖を促し、固液分離が良くなる沈降性の良好な汚泥が得られ、全体として汚泥が減少し、かつ安定な活性汚泥処理ができる。
【００１０】
本発明において、濃厚廃液と希薄排水とは、少なくとも生物学的酸素要求量の値（以下ＢＯＤと略称）または化学的酸素要求量の値（以下ＣＯＤと略称）の差が５００ｐｐｍ以上、好ましくは１０００ｐｐｍ以上あることをいう。すなわち希薄排水よりも濃厚廃液のＢＯＤまたはＣＯＤが５００ｐｐｍ以上大きいことをいう。
また、嫌気処理とは溶存酸素量（以下ＤＯと略称）が０．０５ｐｐｍ未満の状態での処理をいい、好気処理とはＤＯが０．０５ｐｐｍ以上、好ましくは０．１ｐｐｍ以上、より好ましくは０．２ｐｐｍ以上の状態での処理をいう。さらに嫌気処理においては酸化還元電位（以下ＯＲＰと略称）が−８０ｍＶ未満、好気処理においてはＯＲＰが−８０ｍＶ以上、好ましくは正の状態で処理する操作をいう。
【００１１】
【発明の実施の形態】
本発明に係る排水処理方法のフローシートの一例を図１に示す。
排水処理設備は、相互にパイプなどで連絡された活性汚泥処理装置（ＡＲ）と、活性汚泥処理装置（ＢＲ）と、沈殿槽３と、液循環ポンプ４と、液切り替え弁５とを含んで構成されている。
活性汚泥処理装置（ＡＲ）は、嫌気・好気処理を行なえる装置であればよい。例えば、嫌気処理部１ａと好気処理部２ａとがポンプなどを介して相互に連結され、嫌気・好気処理を一つの反応槽内で行なえる活性汚泥反応槽が挙げられる。
【００１２】
本発明に係る排水処理方法のフローシートの他の一例を図２に示す。
排水処理設備は、相互にパイプなどで連絡された活性汚泥処理装置（ＡＲ）と、活性汚泥処理装置（ＢＲ）とを含んで構成され、少なくとも活性汚泥処理装置（ＡＲ）に沈殿槽７と、液循環ポンプ８と、液切り替え弁９とを含んで構成されている。この排水処理設備は、特に活性汚泥処理装置（ＢＲ）容量を大きくできない場合に有効である。
【００１３】
活性汚泥処理装置（ＡＲ）に供給される濃厚廃液（Ａ）は図中矢印の方向に循環される。なお、活性汚泥処理装置（ＡＲ）としては、それぞれ独立した嫌気処理槽および好気処理槽が連結されている活性汚泥処理装置であっても使用できる。
また、活性汚泥処理装置（ＢＲ）は上記活性汚泥処理装置（ＡＲ）と同一方式の装置を使用することができる。濃厚廃液に比較して、希薄排水は処理量が多量となる場合が多いため、それぞれ独立した嫌気処理槽および好気処理槽が連結されている活性汚泥処理装置が好ましい。活性汚泥処理装置（ＢＲ）に供給される希薄排水（Ｂ）は図中矢印の方向に循環される。
【００１４】
活性汚泥処理装置（ＡＲまたはＢＲ）における嫌気・好気処理後、活性汚泥を分離するための沈殿槽３、９としては、加圧浮上分離、常圧浮上分離などの公知の沈殿分離手段が利用できる。
【００１５】
嫌気処理および好気処理を連続して行なうのに適した活性汚泥処理装置（ＡＲまたはＢＲ）として、バイオアルシーシステムがある（日本アルシー株式会社商品名）。バイオアルシーシステムの一例を図３に示す。図３は嫌気・好気処理を連続して行なう微生物反応槽の断面図である。
微生物反応槽１１は、内槽１２と、この内槽１２の上部に設けられた循環率制御装置１３と、外側に設けられた円筒状制御板１４と、外側および内側に設けられた処理水質測定装置１５とから構成されている。
内槽１２は、連結部１２ｃで連結され、その横断面構造が円状をしている好気処理部１２ａと嫌気処理部１２ｂとより構成されている。好気処理部１２ａの容積は嫌気処理部１２ｂの容積の１〜１０倍であることが好ましい。この範囲であると濃厚廃液の好気処理および嫌気処理を効率よく行なうことができる。また、嫌気処理部１２ｂの下部には廃液供給口１６および活性汚泥菌栄養物供給口１７が、好気処理部１２ａの下部より空気取入れ口１８およびアルカリ供給口１９が設けられている。
【００１６】
廃液供給口１７およびアルカリ供給口１９は、ＢＯＤ負荷が小さいにもかかわらず、窒素分濃度が高い濃厚廃液の処理などに好適である。一方、処理される廃液、排水の種類および汚濁の程度等によっては、栄養物供給口１７およびアルカリ供給口１９を省略することができる。
【００１７】
内槽１２内には、攪拌機２０が内設されタービン羽２０ａ、２０ｂおよび２０ｃが設けられている。タービン羽２０ｃは連結部１２ｃの位置に配置されている。タービン羽２０ｃの配置により、好気処理部１２ａから嫌気処理部１２ｂへの処理水の逆流を防ぐことができる。
【００１８】
この内槽１２の外側に円筒状制御板１４ａ、１４ｂ、１４ｃが配置されている。円筒状制御板１４ｂおよび１４ｃ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１５ａ、１５ｂ、１５ｃは、内槽１２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（以下ｐＨと略称）、ＯＲＰ、ＤＯを測定する装置である。なお、２１は浄化された処理水の放流口であり、２２は余剰汚泥引抜き口である。図３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、浮上汚泥を嫌気処理部１２ｂへ戻すポンプ２３を設けることが好ましい。
【００１９】
微生物反応槽１１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、ＯＲＰおよびＤＯ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１３の制御量および空気取入れ口１８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１３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、好気処理部１２ａから内槽１２の外側に配置された円筒状制御板を経て嫌気状態の嫌気処理部１２ｂへ、さらに嫌気処理部１２ｂから好気状態の好気処理部１２ａへと循環することにより、嫌気・好気処理が行なわれる。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、最適な嫌気・好気処理を行なうことができる。
【００２０】
内槽を構成する好気処理部の容積は嫌気処理部の容積より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、濃厚汚泥を含有する廃水の最適な嫌気・好気処理を行なうことができる。特に濃厚汚泥を含有する原水における嫌気処理と好気処理とのバランスを保ことができる。
【００２１】
上記微生物反応槽内での処理水循環率は２〜２０、好ましくは５〜２０である。処理水循環率が２未満であると、好気処理がより起こりやすくなり、また、２０をこえると好気処理と嫌気処理とのバランスが崩れる。すなわち、処理水循環率をこの範囲とすることにより、好気処理および嫌気処理が十分に行なわれ、活性汚泥菌体が馴養されやすくなる。なお、このような条件下において好気処理部でのｐＨは４．５〜８．５、好ましくは５．５〜７．５の範囲となる。
【００２２】
活性汚泥処理装置（ＢＲ）は上記活性汚泥処理装置（ＡＲ）と同一方式の装置を使用することができる。濃厚廃液（Ａ）に比較して、希薄排水（Ｂ）は処理量が多量となる場合が多いため、それぞれ独立した嫌気処理槽および好気処理槽が連結されている活性汚泥処理装置が好ましい。
また、嫌気処理槽と好気処理槽とをポンプで循環する方法で循環量を調整する方法も処理槽容積を少なくする方法として有効である。
【００２３】
活性汚泥処理装置（ＢＲ）における嫌気・好気処理後、活性汚泥を分離するための沈殿槽３としては、加圧浮上分離、常圧浮上分離などの公知の沈殿分離手段が利用できる。
特に、ばっ気空気で嫌気処理槽と好気処理槽と沈殿槽の間を自然循環させ、沈殿部に強制沈降を導入した設備で自然循環量を調整できる構造の処理設備が処理槽容積が少なくてすむので好ましい。
【００２４】
活性汚泥処理装置（ＡＲ）に供給された濃厚廃液は嫌気処理部１ａおよび好気処理部２ａにおける処理を連続して少なくとも１回以上繰り返すことが好ましい。より好ましくは２〜４回である。
【００２５】
図１において、濃厚廃液は活性汚泥処理装置（ＡＲ）の嫌気処理部１ａに供給されて嫌気処理される。また必要に応じて濃厚廃液が供給される嫌気処理部１ａには後述する返送汚泥が供給され、同時に嫌気・好気処理される。嫌気処理時間は０．５〜６時間が好ましく、１〜２時間がより好ましい。嫌気処理時間が０．５時間未満では嫌気菌体の増殖が不十分であり、６時間をこえると好気菌体の活性が低下し、好気菌体の増殖が好気条件下でも不十分となり好気処理に悪影響が現れる。
また、上記嫌気処理後引き続いてなされる好気処理部２ａにおける好気処理の時間は１〜１０時間が好ましく、２〜６時間がより好ましい。好気処理時間が１時間未満では好気菌体の増殖が不十分であり、１０時間をこえると嫌気菌体の数が減少して嫌気処理部での嫌気菌体の増殖に悪影響が現れ処理の安定性が損なわれる。
本発明においては、活性汚泥処理装置（ＡＲ）内の嫌気処理部１ａおよび好気処理部２ａにおいて濃厚廃液は嫌気・好気処理を繰り返すことにより、濃厚廃液が難分解性有機物を含む高濃度の廃液であっても活性汚泥処理菌体が馴養されやすくなる。
【００２６】
活性汚泥処理装置（ＡＲ）内にて循環処理された濃厚廃液は、固液分離されることなく好気処理部２ａから活性汚泥処理装置（ＢＲ）の嫌気処理部１ｂに供給される。この活性汚泥処理装置（ＢＲ）の嫌気処理部１ｂには、同時に希薄排水（Ｂ）が供給される。
活性汚泥処理装置（ＢＲ）に供給された、希薄排水および嫌気・好気処理された後の濃厚廃液は、嫌気処理部１ｂおよび好気処理部２ｂにおける処理を連続して少なくとも１回以上繰り返すことが好ましい。より好ましくは２〜４回である。嫌気処理および好気処理条件は活性汚泥処理装置（ＡＲ）と同様に行なうことができる。
【００２７】
図２に示す活性汚泥処理装置（ＡＲ）に沈殿槽を設けた場合には、活性汚泥処理装置（ＡＲ）内にて循環処理された濃厚廃液を沈殿槽７に集め固液分離を行ない、分離された汚泥を液循環ポンプ８と液切り替え弁９とを介して、活性汚泥処理装置（ＡＲ）の嫌気処理部１ａに返送汚泥１０ａとして戻すことができる。また、活性汚泥処理装置（ＡＲ）と活性汚泥処理装置（ＢＲ）との両方の活性汚泥処理装置に返送汚泥１０ｂとして戻すことができる。なお、活性汚泥を分離した上澄みは活性汚泥処理装置（ＢＲ）に戻すことができる。
【００２８】
活性汚泥処理装置（ＢＲ）における嫌気・好気処理後、好気処理部２ｂより処理液を沈殿槽３に集め、公知の方法で固液分離を行なう。分離された汚泥は液循環ポンプ４と液切り替え弁５とを介して、活性汚泥処理装置（ＡＲ）の嫌気処理部１ａに返送汚泥６として戻す。または嫌気処理部１ａと同時に活性汚泥処理装置（ＢＲ）の嫌気処理部１ｂに戻すことができる。返送汚泥６は濃厚廃液および希薄排水に馴養されているので、難分解性の高分子の汚濁物質を多く含有している廃液を処理する場合でも処理効率が向上し処理水中の汚濁物質濃度の低減が著しく向上するのみならず、バルキングが発生し難くなり、汚泥発生量が大幅に減少するので脱水ケーキの処分費用が著しく削減されるのと、汚泥の自己溶菌で微生物の良好な栄養分が供給されるので、その後の活性汚泥処理がより効率よく行なえる。
【００２９】
また、本発明においては、活性汚泥処理装置（ＡＲ）と活性汚泥処理装置（ＢＲ）とに分離して排水処理を行なうことで、最適条件での嫌気・好気処理ができるため活性汚泥処理装置の微生物反応処理槽の容積を小さくできるので、既設の設備の処理能力向上ならびに排水処理設備建設費用の削減が図れる。また、汚泥の発生量が少ないので脱水設備も従来の能力の半分以下の設備で対応でき、設備投資額ならびにランニングコストを大幅に削減できる。
【００３０】
さらに、活性汚泥処理装置（ＡＲ）と活性汚泥処理装置（ＢＲ）とを組み合わせることで、濃厚廃液を前処理することなく有機物の消化が十分になされ、微生物硝化脱窒が十分になされるので、余剰汚泥を少なくできる。余剰汚泥が完熟汚泥となり臭気が少なくなる。凝集剤の添加がすくなくなるので余剰汚泥の含水率が下がる等の効果である。
なお、活性汚泥処理装置（ＡＲ）と活性汚泥処理装置（ＢＲ）とはそれぞれ複数段組み合わせることができる。
【００３１】
本発明の排水処理方法は、例えば、食品産業、塗装産業、機械産業、製紙産業、化学薬品産業等おいて、特に濃厚廃液と希薄排水とが発生する分野の排水を処理するに適している。
【００３２】
【実施例】
実施例１
食鳥処理排水処理場から排出される排水を処理した。
排水は通常放血された血液（ＣＯＤ；２００００ｐｐｍ以上）や砂肝の周囲に付着している脂肪分を剥離した固形分や油分含有廃液（ノルマルヘキサン抽出量（以下ｎ−Ｈｅｘと略称）；５００ｐｐｍ以上、ＣＯＤ；１５００ｐｐｍ以上）は分別回収して場外処分するのが通常であるが、近年産業廃棄物の処分費の高騰により排水処理装置での処理が要望されている。
これらの血液や油分を含有する廃液は濃厚廃液と称し、ＣＯＤが６５００ｐｐｍ、ＢＯＤが１３５００ｐｐｍ、ｎ−Ｈｅｘが１５００ｐｐｍ、全窒素（以下、Ｔ−Ｎと略称する）が５５０ｐｐｍ含まれる濃厚廃液が１５トン／日排出し、その他、希薄排水として、食鳥の中貫洗浄排水（ＣＯＤが４５０ｐｐｍ、ＢＯＤが１１００ｐｐｍ）が３６０トン／日排出している。
濃厚廃液処理用装置（ＡＲ）は、容積５０ｍ^３の嫌気処理部１ａと、容積１２０ｍ^３の好気処理部２ａとを有している。また、希薄排水処理用装置（ＢＲ）は、嫌気処理部１ｂが容積８０ｍ^３で、好気処理部２ｂが容積１８０ｍ^３で強制沈殿部３が容積１６０ｍ^３の循環式嫌気・好気処理槽（バイオアルシーシステム：日本アルシー株式会社商品名）を用いた。
【００３３】
循環式嫌気・好気処理槽（バイオアルシーシステム）に循環率４倍で希薄排水１５トン／Ｈと濃厚廃液処理用装置（ＡＲ）からで処理した好気部の汚泥を６３０Ｌ／Ｈをそれぞれ連続的に供給して混合し排水処理した。なお、循環式嫌気・好気処理槽の沈殿部から汚泥を濃厚廃液処理用装置（ＡＲ）の嫌気部に５００Ｌ／Ｈ、連続的に移送した。
希薄排水処理用装置（ＢＲ）からの放流水の水質は、ＢＯＤが１１ｐｐｍ、ＣＯＤが１８ｐｐｍ、ｎ−Ｈｅｘが０．１ｐｐｍ、Ｔ−Ｎが１２ｐｐｍであった。また、希薄排水処理用装置（ＢＲ）の沈殿部から余剰汚泥を引き抜き脱水した。余剰汚泥の脱水ケーキ処分量は年間１３トンであった。
【００３４】
比較例１
食鳥処理排水処理場から排出される排水を２段ばっ気法にて処理した。２段ばっ気法は容積１８０ｍ^３のばっ気槽とその後に４５ｍ^３の沈殿槽があり、次いで容積１２０ｍ^３のばっ気槽とその後に６０ｍ^３の沈殿槽を備えた設備で活性汚泥処理をした。
食鳥の放血は全量回収して産業廃棄物処理業者に委託処分をしていた。油まじりの原水は硫酸バンドと苛性ソーダならびにアニオン系の高分子凝集剤で前処理を実施し加圧浮上スカムをスクリュープレスで脱水し脱水ケーキを委託処分していた。脱水ケーキを委託処分量は年間９６０トンであった。また、排水処理後の水質は、ＢＯＤが１２ｐｐｍ、ＣＯＤが２０ｐｐｍ、ｎ−Ｈｅｘが０．１ｐｐｍ、Ｔ−Ｎが４０ｐｐｍであった。
【００３５】
実施例２
化学薬品製造工場から排出される排水を処理した。
排水は、ＢＯＤが８４００ｐｐｍ、ＣＯＤが４５００ｐｐｍ、Ｔ−Ｎが６８２ｐｐｍの濃厚廃液が平均２．４トン／Ｈ、ＢＯＤが２６０ｐｐｍ、ＣＯＤが１３０ｐｐｍ、全窒素量が３４ｐｐｍの希薄排水が平均１９トン／Ｈそれぞれ排出している。
濃厚廃液処理用装置（ＡＲ）は、容積１００ｍ^３と容積７０ｍ^３との嫌気処理部１ａと、容積１００ｍ^３と容積７０ｍ^３との好気処理部２ａとを有している。
また、希薄排水処理用装置（ＢＲ）は、容積２００ｍ^３の嫌気処理部１ｂが２つと、容積２００ｍ^３の好気処理部２ｂが２つとを有している。
【００３６】
濃厚廃液を濃厚廃液処理用装置（ＡＲ）に返送汚泥０．２トン／Ｈとともに嫌気処理部１ａに投入して嫌気処理を行ない、次いで好気処理部２ａに移し好気処理を行ない、嫌気・好気処理を２回繰り返した。嫌気処理時間はそれぞれ１．２時間、好気処理時間はそれぞれ４時間の割合で行なった。
その後、希薄排水処理用装置（ＢＲ）の嫌気処理部１ｂに希薄排水とともに投入して嫌気処理を行ない、次いで好気処理部２ｂに移し好気処理を行ない、嫌気・好気処理を２回繰り返した。嫌気処理時間はそれぞれ１．１時間、好気処理時間はそれぞれ３．５時間の割合で行なった。
【００３７】
沈殿槽３を使用して活性汚泥から処理水を分離して放流水を取り出し、沈降濃縮された活性汚泥は返送汚泥として循環使用し、一部は余剰汚泥として抜き出して凝集脱水し脱水ケーキとした。
放流水の水質はＢＯＤが１３ｐｐｍ、ＣＯＤが９ｐｐｍ、Ｔ−Ｎが５ｐｐｍであった。また脱水ケーキは０．１トン／Ｈであった。
【００３８】
比較例２
実施例で処理すべき水質および処理量の排水を好気処理のみで排水処理した。
排水処理装置は容積２００ｍ^３と容積３７０ｍ^３の好気処理槽とを連結した。
濃厚廃液と希薄排水とを排出量に応じて混合して上記好気処理槽で処理した。処理された放流水の水質はＢＯＤが１３ｐｐｍ、ＣＯＤが１０ｐｐｍ、Ｔ−Ｎが４１ｐｐｍであった。また脱水ケーキは０．４トン／Ｈであった。
【００３９】
実施例３
味噌醸造工場から排出される排水を処理した。
排水は、濃厚廃液として大豆煮汁廃液が１トン／日および米とぎ汁廃液が５０トン／日排出している。この濃厚廃液はＢＯＤが３５００ｐｐｍ、ＣＯＤが１８００ｐｐｍ、Ｔ−Ｎが３００ｐｐｍである。
また、ＢＯＤが４００ｐｐｍ、ＣＯＤが２５０ｐｐｍ、Ｔ−Ｎが１５ｐｐｍの希薄排水が１０００トン／日排出している。
濃厚廃液処理用装置（ＡＲ）は、容積２０ｍ^３の嫌気処理部１ａと、容積６０ｍ^３の好気処理部２ａとを有している。
また、希薄排水処理用装置（ＢＲ）は、容積１００ｍ^３の嫌気処理部１ｂと、容積４００ｍ^３の好気処理部２ｂとを有している。
【００４０】
濃厚廃液を濃厚廃液処理用装置（ＡＲ）に返送汚泥８トン／Ｈとともに嫌気処理部１ａに投入して、嫌気処理時間を２時間、好気処理時間を６時間の割合で嫌気・好気処理を２回繰り返して行なった。
その後、希薄排水処理用装置（ＢＲ）の嫌気処理部１ｂに希薄排水とともに投入して嫌気処理を行ない、次いで好気処理部２ｂに移し好気処理を行ない、嫌気・好気処理を２回繰り返した。嫌気処理時間はそれぞれ２時間、好気処理時間はそれぞれ５時間の割合で行なった。
【００４１】
沈殿槽３を使用して活性汚泥から処理水を分離して放流水を取り出し、沈降濃縮された活性汚泥は返送汚泥として循環使用し、一部は余剰汚泥として抜き出して凝集脱水し脱水ケーキとした。
放流水の水質はＢＯＤが８ｐｐｍ、ＣＯＤが１９ｐｐｍ、Ｔ−Ｎが１ｐｐｍ以下であった。また脱水ケーキは１トン／日であった。
【００４２】
比較例３
実施例３での味噌醸造工場から排出される排水を容積１０００ｍ^３のばっ気槽で処理した。この場合、処理された放流水の水質はＢＯＤが８ｐｐｍ、ＣＯＤが２０ｐｐｍ、Ｔ−Ｎが５ｐｐｍであった。また脱水ケーキは４トン／日であった。
【００４３】
【発明の効果】
本発明の排水処理方法は、濃厚廃液と希薄排水とをそれぞれ処理する活性汚泥処理装置を設け、濃厚廃液を活性汚泥処理した後に希薄排水と混合して活性汚泥処理するので、活性汚泥菌体が馴養し易くなり、バルキングが起こり難くなり排水処理能力が向上する。また、汚泥の発生量を削減することができる。
【００４４】
また、上記排水処理方法において、希薄排水処理より発生した汚泥を返送汚泥とするので、活性汚泥菌体がより容易に馴養される。
【００４５】
また、上記排水処理方法において、活性汚泥処理装置（ＡＲ）における嫌気・好気処理条件は、嫌気処理時間が０．５〜６時間、好気処理時間が１〜１０時間の範囲で、嫌気・好気処理を１回または複数回行なうので、排水処理装置全体の装置容積を少なくできる。
【図面の簡単な説明】
【図１】排水処理方法のフローシートである。
【図２】排水処理方法の他のフローシートである。
【図３】微生物反応槽の断面図である。
【符号の説明】
１嫌気処理部
２好気処理部
３沈殿槽
４液循環ポンプ
５液切り替え弁
６返送汚泥[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wastewater treatment method, and particularly to a wastewater treatment method for treating a concentrated waste liquid and a lean wastewater.
[0002]
[Prior art]
The wastewater discharged from production sites and public facilities often contains concentrated wastewater with a high concentration of specific pollutants and dilute wastewater with a relatively low concentration of pollutants called miscellaneous wastewater. .
Conventionally, when these wastewaters are treated using wastewater treatment equipment by the activated sludge method, the concentrated waste liquid and the diluted wastewater are directly subjected to anaerobic treatment or the like, and then the activated sludge is polluted. The concentrated waste liquid and the dilute wastewater are mixed and treated so that the substance has a constant load.
In addition, when the wastewater treatment capacity of activated sludge is reduced due to fluctuations in the water quality of the wastewater flowing into the activated sludge tank, bacteria in the sludge whose bacterial count has been dramatically reduced due to water quality fluctuations are individually cultured using a complete nutrient medium outside the activated sludge tank. In order to reduce the number of days required for acclimation by introducing the activated sludge into the activated sludge tank, the activated sludge was previously collected from the activated sludge tank showing a good wastewater treatment capacity, and collected. There is known a wastewater treatment method in which a large number of bacteria involved in organic matter decomposition are separated from activated sludge, and the characteristics of those bacteria are confirmed and stored (see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-6-277686 (claims)
[0004]
[Problems to be solved by the invention]
However, when the concentrated waste liquid and the dilute wastewater are directly mixed, there is a problem that the water quality fluctuates greatly and the ability of activated sludge treatment is reduced.
In addition, when the concentrated waste liquid is subjected to anaerobic treatment, a large amount of hydrogen sulfide gas and ammonia gas are likely to be generated. For this reason, when the concentrated waste liquid after anaerobic treatment is mixed with the diluted waste water, a bulking phenomenon and demolition of activated sludge occur. There is a problem that wastewater treatment becomes more frequent and the wastewater treatment becomes unstable.
In addition, even if bacterial cells rapidly grown by individual culture using a complete nutrient medium outside the activated sludge tank are used, it becomes difficult to reduce the number of days required for acclimatization when the type of concentrated waste liquid or diluted wastewater increases. Problem.
[0005]
The present invention has been made in order to address such a problem, and even when treating a concentrated waste liquid and a dilute wastewater, the activated sludge cells are stabilized so that the wastewater treatment capacity is improved, and It is an object of the present invention to provide a wastewater treatment method in which activated sludge cells are easily acclimated even in the case of a concentrated waste liquid containing many persistent pollutants.
[0006]
[Means for Solving the Problems]
An invention according to claim 1 is a wastewater treatment method for treating a concentrated waste liquid and a lean wastewater, wherein the activated sludge treatment apparatus (AR) for treating the concentrated waste liquid and the activated sludge treatment apparatus (BR) for treating the lean wastewater are provided. A step of subjecting the concentrated waste liquid to anaerobic / aerobic treatment in the activated sludge treatment apparatus (AR); and a step of performing an activated sludge treatment apparatus (BR) without solid-liquid separation of the concentrated waste liquid after the anaerobic / aerobic treatment. And performing a anaerobic / aerobic treatment together with the dilute drainage.
According to a second aspect of the present invention, in the wastewater treatment method according to the first aspect, after the anaerobic / aerobic treatment in the activated sludge treatment apparatus (BR), the activated sludge is separated and returned to the activated sludge treatment apparatus (AR). Or a step of returning to both the activated sludge treatment device (AR) and the activated sludge treatment device (BR).
[0007]
According to a third aspect of the present invention, there is provided a wastewater treatment method for treating a concentrated waste liquid and a lean wastewater, wherein the activated sludge treatment apparatus (AR) for treating the concentrated waste liquid and the activated sludge treatment apparatus (BR) for treating the lean wastewater are provided. A step of performing anaerobic / aerobic treatment of the concentrated waste liquid in an activated sludge treatment apparatus (AR), and separating the activated sludge after the anaerobic / aerobic treatment and returning the activated sludge to the activated sludge treatment apparatus (AR); Return to the activated sludge treatment device (BR), or return to both the activated sludge treatment device (AR) and the activated sludge treatment device (BR), and separate the activated sludge into the activated sludge treatment device (BR).
[0008]
According to a fourth aspect of the present invention, in the wastewater treatment method according to the first or third aspect, the anaerobic / aerobic treatment conditions in the activated sludge treatment apparatus (AR) are set such that the anaerobic treatment time is 0.5 to 6 hours. The anaerobic / aerobic treatment is performed once or plural times within a range of 1 to 10 hours.
According to a fifth aspect of the present invention, in the wastewater treatment method according to the first or third aspect, the anaerobic / aerobic treatment conditions in the activated sludge treatment apparatus (BR) are such that the anaerobic treatment time is 0.5 to 6 hours. The anaerobic / aerobic treatment is performed at a circulation rate of 2 to 20 times that of the dilute wastewater in a range of 1 to 10 hours.
[0009]
An anaerobic / aerobic treatment of the concentrated waste liquid in an activated sludge treatment device (AR) and a dilute wastewater in an activated sludge treatment device (BR) without solid-liquid separation of the concentrated waste liquid after the anaerobic / aerobic treatment By combining the anaerobic and aerobic treatment steps, the respective growth processes and nutrient metabolism processes of the anaerobic activated sludge cells and the aerobic activated sludge cells are combined, and the anaerobic activated sludge cells and the anaerobic activated sludge cells are combined. The growth of aerobic activated sludge cells is maximized.
That is, in the anaerobic treatment step, the high molecular weight polysaccharides secreted by the aerobic activated sludge cells are decomposed, and in the aerobic treatment step, the anaerobic activated sludge cells are digested to reduce sludge volume and aerobic activated sludge bacteria. Sludge with good sedimentation, which promotes body growth and improves solid-liquid separation, is obtained, and sludge is reduced as a whole, and stable activated sludge treatment can be performed.
[0010]
In the present invention, the difference between the value of the biological oxygen demand (hereinafter abbreviated as BOD) or the value of the chemical oxygen demand (hereinafter abbreviated as COD) is at least 500 ppm, preferably 1000 ppm, between the concentrated waste liquid and the lean wastewater. It means that there is. That is, it means that the BOD or COD of the concentrated waste liquid is 500 ppm or more larger than that of the diluted waste water.
Anaerobic treatment refers to treatment in a state in which the amount of dissolved oxygen (hereinafter abbreviated as DO) is less than 0.05 ppm, and aerobic treatment refers to DO having 0.05 ppm or more, preferably 0.1 ppm or more, more preferably It means the treatment in the state of 0.2 ppm or more. Further, in anaerobic treatment, the oxidation-reduction potential (hereinafter, abbreviated as ORP) is less than -80 mV, and in aerobic treatment, the ORP is -80 mV or more, preferably in a positive state.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an example of a flow sheet of the wastewater treatment method according to the present invention.
The wastewater treatment equipment includes an activated sludge treatment device (AR), an activated sludge treatment device (BR), a sedimentation tank 3, a liquid circulation pump 4, and a liquid switching valve 5 mutually connected by a pipe or the like. It is configured.
The activated sludge treatment device (AR) may be any device that can perform anaerobic / aerobic treatment. For example, there is an activated sludge reaction tank in which the anaerobic treatment section 1a and the aerobic treatment section 2a are connected to each other via a pump or the like so that anaerobic / aerobic treatment can be performed in one reaction tank.
[0012]
FIG. 2 shows another example of the flow sheet of the wastewater treatment method according to the present invention.
The wastewater treatment equipment includes an activated sludge treatment device (AR) and an activated sludge treatment device (BR) that are connected to each other by a pipe or the like. At least the activated sludge treatment device (AR) includes a sedimentation tank 7; It is configured to include a liquid circulation pump 8 and a liquid switching valve 9. This wastewater treatment equipment is particularly effective when the capacity of the activated sludge treatment equipment (BR) cannot be increased.
[0013]
The concentrated waste liquid (A) supplied to the activated sludge treatment device (AR) is circulated in the direction of the arrow in the figure. As the activated sludge treatment device (AR), an activated sludge treatment device in which independent anaerobic treatment tanks and aerobic treatment tanks are connected can be used.
As the activated sludge treatment device (BR), a device of the same type as the activated sludge treatment device (AR) can be used. Activated sludge treatment equipment in which independent anaerobic treatment tanks and aerobic treatment tanks are connected to each other is preferred since the amount of treated wastewater is often larger than that of concentrated wastewater. The lean wastewater (B) supplied to the activated sludge treatment device (BR) is circulated in the direction of the arrow in the figure.
[0014]
As the sedimentation tanks 3 and 9 for separating the activated sludge after the anaerobic / aerobic treatment in the activated sludge treatment device (AR or BR), known sedimentation separation means such as pressurized flotation and normal pressure flotation are used. it can.
[0015]
As an activated sludge treatment apparatus (AR or BR) suitable for continuously performing anaerobic treatment and aerobic treatment, there is a bio-alcy system (trade name of Nippon Alcy Corporation). FIG. 3 shows an example of the bio-alcy system. FIG. 3 is a sectional view of a microorganism reaction tank that continuously performs anaerobic / aerobic treatment.
The microorganism reaction tank 11 includes an inner tank 12, a circulation rate control device 13 provided on the upper part of the inner tank 12, a cylindrical control plate 14 provided on the outside, and a treatment water quality measurement provided on the outside and the inside. And an apparatus 15.
The inner tank 12 is connected by a connecting portion 12c, and includes an aerobic processing portion 12a and an anaerobic processing portion 12b having a circular cross-sectional structure. The volume of the aerobic treatment section 12a is preferably 1 to 10 times the volume of the anaerobic treatment section 12b. Within this range, aerobic treatment and anaerobic treatment of the concentrated waste liquid can be performed efficiently. Further, a waste liquid supply port 16 and an activated sludge nutrient supply port 17 are provided below the anaerobic treatment section 12b, and an air intake port 18 and an alkali supply port 19 are provided below the aerobic treatment section 12a.
[0016]
The waste liquid supply port 17 and the alkali supply port 19 are suitable for processing a concentrated waste liquid having a high nitrogen content despite a small BOD load. On the other hand, the nutrient supply port 17 and the alkali supply port 19 can be omitted depending on the type of waste liquid to be treated, the type of wastewater, and the degree of contamination.
[0017]
In the inner tank 12, a stirrer 20 is provided and turbine blades 20a, 20b, and 20c are provided. The turbine blade 20c is arranged at the position of the connecting portion 12c. The arrangement of the turbine blades 20c can prevent backflow of the treated water from the aerobic treatment section 12a to the anaerobic treatment section 12b.
[0018]
Outside the inner tank 12, cylindrical control plates 14a, 14b, 14c are arranged. The cylindrical control plates 14b and 14c have a predetermined inclination. This inclination is set at an angle that allows rapid forced settling. Further, the treated water quality measuring devices 15a, 15b, 15c are provided inside and outside the inner tank 12. This treatment water quality measuring device is a device for measuring the hydrogen ion concentration (hereinafter abbreviated as pH), ORP and DO of treated water. In addition, 21 is a discharge port of the purified treated water, and 22 is an excess sludge extraction port. In FIG. 3, the hatched portion at the bottom of the reaction tank indicates a settled layer of activated sludge. Further, it is preferable to provide a pump 23 for returning the floating sludge to the anaerobic treatment section 12b.
[0019]
The microbial reaction tank 11 further has means for detecting at least one measurement value selected from pH, ORP, and DO of the treated water measured by the treated water quality measuring device. According to the detection value detected by this means, the control amount is selected from the control amount of the circulation rate control device 13 and the amount of air blown from the air intake 18 by a control program electronically stored in a memory of the control device in advance. Control at least one quantity. Specifically, the control amount of the circulation rate control device 13 is determined by opening / closing a 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 aerobic treatment section 12a to the anaerobic treatment section 12b in the anaerobic state through a cylindrical control plate disposed outside the inner tank 12, and further from the anaerobic treatment section 12b. By circulating to the air processing unit 12a, anaerobic / aerobic processing is performed. Therefore, optimal anaerobic / aerobic treatment can be performed by controlling the circulation rate of the treated water based on the predetermined control program according to the detected value.
[0020]
The volume of the aerobic treatment section constituting the inner tank is set to 1 to 10 times, more preferably 4 to 10 times the volume of the anaerobic treatment section. By setting it in this range, it is possible to perform optimal anaerobic / aerobic treatment of wastewater containing concentrated sludge. In particular, the balance between the anaerobic treatment and the aerobic treatment in the raw water containing the thick sludge can be maintained.
[0021]
The circulating rate of the treated water in the microorganism reaction tank is 2 to 20, preferably 5 to 20. When the treated water circulation rate is less than 2, aerobic treatment is more likely to occur, and when it exceeds 20, the balance between aerobic treatment and anaerobic treatment is lost. That is, by setting the treated water circulation rate within this range, aerobic treatment and anaerobic treatment are sufficiently performed, and the activated sludge cells are easily acclimated. In addition, under such conditions, the pH in the aerobic treatment section is in the range of 4.5 to 8.5, preferably 5.5 to 7.5.
[0022]
The activated sludge treatment device (BR) can use the same type of device as the activated sludge treatment device (AR). Since the amount of the treated wastewater (B) often becomes larger than that of the concentrated waste liquid (A), an activated sludge treatment apparatus in which independent anaerobic treatment tanks and aerobic treatment tanks are connected is preferable.
Further, a method of adjusting the circulation amount by circulating the anaerobic treatment tank and the aerobic treatment tank with a pump is also effective as a method of reducing the treatment tank volume.
[0023]
As the sedimentation tank 3 for separating the activated sludge after the anaerobic / aerobic treatment in the activated sludge treatment apparatus (BR), known sedimentation separation means such as pressurized flotation and normal pressure flotation can be used.
In particular, processing equipment with a structure that allows natural circulation between the anaerobic treatment tank, aerobic treatment tank, and sedimentation tank with aerated air and that can adjust the natural circulation amount with equipment that introduced forced sedimentation in the sedimentation section has a small processing tank volume. It is preferable because it can be used.
[0024]
It is preferable that the concentrated waste liquid supplied to the activated sludge treatment apparatus (AR) is subjected to the treatment in the anaerobic treatment section 1a and the aerobic treatment section 2a continuously at least once or more. More preferably, it is 2 to 4 times.
[0025]
In FIG. 1, the concentrated waste liquid is supplied to an anaerobic treatment section 1a of an activated sludge treatment apparatus (AR) and subjected to anaerobic treatment. Further, returned sludge, which will be described later, is supplied to the anaerobic treatment section 1a to which the concentrated waste liquid is supplied as necessary, and at the same time, is subjected to anaerobic / aerobic treatment. The anaerobic treatment time is preferably 0.5 to 6 hours, more preferably 1 to 2 hours. When the anaerobic treatment time is less than 0.5 hours, the growth of the anaerobic cells is insufficient, and when it exceeds 6 hours, the activity of the aerobic cells decreases, and the growth of the aerobic cells is insufficient even under the aerobic condition. This has an adverse effect on aerobic treatment.
The time of the aerobic treatment in the aerobic treatment section 2a which is performed after the anaerobic treatment is preferably 1 to 10 hours, more preferably 2 to 6 hours. If the aerobic treatment time is less than 1 hour, the growth of the aerobic cells is insufficient, and if it exceeds 10 hours, the number of the anaerobic cells decreases and the growth of the anaerobic cells in the anaerobic treatment section is adversely affected. Stability is impaired.
In the present invention, the concentrated waste liquid is repeatedly subjected to anaerobic / aerobic treatment in the anaerobic treatment section 1a and the aerobic treatment section 2a in the activated sludge treatment apparatus (AR), so that the concentrated waste liquid has a high concentration containing a hardly decomposable organic substance. Activated sludge treated cells can be easily acclimated even with waste liquid.
[0026]
The concentrated waste liquid circulated in the activated sludge treatment device (AR) is supplied from the aerobic treatment portion 2a to the anaerobic treatment portion 1b of the activated sludge treatment device (BR) without solid-liquid separation. At the same time, the lean effluent (B) is supplied to the anaerobic treatment section 1b of the activated sludge treatment apparatus (BR).
The diluted wastewater supplied to the activated sludge treatment apparatus (BR) and the concentrated waste liquid after the anaerobic / aerobic treatment are continuously and repeatedly subjected to the treatment in the anaerobic treatment section 1b and the aerobic treatment section 2b at least once. Is preferred. More preferably, it is 2 to 4 times. The anaerobic treatment and the aerobic treatment can be performed in the same manner as in the activated sludge treatment apparatus (AR).
[0027]
When the activated sludge treatment apparatus (AR) shown in FIG. 2 is provided with a sedimentation tank, the concentrated waste liquid circulated in the activated sludge treatment apparatus (AR) is collected in the sedimentation tank 7 and solid-liquid separation is performed. The sludge thus collected can be returned to the anaerobic treatment section 1a of the activated sludge treatment device (AR) as the return sludge 10a via the liquid circulation pump 8 and the liquid switching valve 9. Further, the sludge can be returned to both the activated sludge treatment device (AR) and the activated sludge treatment device (BR) as the returned sludge 10b. The supernatant from which the activated sludge has been separated can be returned to the activated sludge treatment device (BR).
[0028]
After the anaerobic / aerobic treatment in the activated sludge treatment device (BR), the treatment liquid is collected in the sedimentation tank 3 from the aerobic treatment section 2b, and solid-liquid separation is performed by a known method. The separated sludge is returned to the anaerobic treatment section 1a of the activated sludge treatment device (AR) as returned sludge 6 via the liquid circulation pump 4 and the liquid switching valve 5. Alternatively, it can be returned to the anaerobic treatment section 1b of the activated sludge treatment apparatus (BR) simultaneously with the anaerobic treatment section 1a. Since the returned sludge 6 is acclimated to the concentrated waste liquid and the diluted wastewater, the processing efficiency is improved and the concentration of the pollutants in the treated water is reduced even when treating the waste liquid containing a large amount of the insoluble polymer pollutants. In addition to the significant improvement in sludge generation, bulking is less likely to occur, and the amount of sludge generated is significantly reduced, which significantly reduces the cost of disposing of dewatered cakes. Therefore, the subsequent activated sludge treatment can be performed more efficiently.
[0029]
In the present invention, the activated sludge treatment apparatus is separated into an activated sludge treatment apparatus (AR) and an activated sludge treatment apparatus (BR) to perform anaerobic / aerobic treatment under optimum conditions. Since the volume of the microbial reaction treatment tank can be reduced, the treatment capacity of the existing equipment can be improved and the cost of constructing the wastewater treatment equipment can be reduced. In addition, since the amount of generated sludge is small, the dewatering equipment can be used with equipment having less than half of the conventional capacity, and the capital investment and running cost can be greatly reduced.
[0030]
Further, by combining the activated sludge treatment device (AR) and the activated sludge treatment device (BR), the digestion of organic substances can be sufficiently performed without pretreating the concentrated waste liquid, and the nitrification and denitrification of microorganisms can be sufficiently performed. Excess sludge can be reduced. Excess sludge turns into fully matured sludge, which reduces odor. Since the addition of the coagulant is reduced, the water content of the excess sludge is reduced.
The activated sludge treatment device (AR) and the activated sludge treatment device (BR) can be combined in multiple stages.
[0031]
The wastewater treatment method of the present invention is suitable, for example, for treating wastewater in fields in which concentrated waste liquid and dilute wastewater are generated in the food industry, the coating industry, the machine industry, the paper industry, the chemical industry, and the like.
[0032]
【Example】
Example 1
Wastewater discharged from the poultry processing wastewater treatment plant was treated.
The drainage is usually blood exsanguinated (COD; 20,000 ppm or more) or solids or oil-containing waste liquid (oil-extracted normal hexane (hereinafter abbreviated as n-Hex); , COD; 1500 ppm or more) is usually separated and collected and disposed of off-site. However, in recent years, the cost of disposing of industrial waste has risen, and there is a demand for treatment with a wastewater treatment device.
These waste liquids containing blood and oil are referred to as concentrated waste liquid, and 15 tons of concentrated waste liquid containing 6500 ppm of COD, 13500 ppm of BOD, 1500 ppm of n-Hex, and 550 ppm of total nitrogen (hereinafter abbreviated as TN). / Day, and 360 tons / day of poultry poultry washing wastewater (COD: 450 ppm, BOD: 1100 ppm) as a dilute wastewater.
The equipment for concentrated waste liquid treatment (AR) has a capacity of 50m ³ Anaerobic treatment part 1a, volume 120m ³ Aerobic processing unit 2a. In addition, in the apparatus (BR) for lean wastewater treatment, the anaerobic treatment part 1b has a capacity of 80 m. ³ The aerobic processing unit 2b has a capacity of 180 m ³ The forced sedimentation section 3 has a capacity of 160m ³ A circulating anaerobic / aerobic treatment tank (Bio-Arcy System: Nippon Arcy Co., Ltd.) was used.
[0033]
Continuous circulation anaerobic / aerobic treatment tank (bio-alcy system) with a circulation rate of 4 times and dilute wastewater of 15 tons / H and aerobic part sludge treated with concentrated waste liquid treatment equipment (AR) at 630 L / H continuously The mixture was supplied, mixed and drained. The sludge was continuously transferred at 500 L / H from the sedimentation section of the circulation type anaerobic / aerobic treatment tank to the anaerobic section of the concentrated waste liquid treatment apparatus (AR).
The water quality of the effluent from the lean wastewater treatment apparatus (BR) was 11 ppm for BOD, 18 ppm for COD, 0.1 ppm for n-Hex, and 12 ppm for TN. In addition, excess sludge was pulled out from the sedimentation section of the lean wastewater treatment apparatus (BR) and dewatered. The disposal amount of dewatered cake of excess sludge was 13 tons per year.
[0034]
Comparative Example 1
Wastewater discharged from the poultry processing wastewater treatment plant was treated by a two-stage aeration method. 180m capacity for two-stage aeration method ³ No aeration tank and then 45m ³ There is a sedimentation tank of 120m ³ No aeration tank and then 60m ³ Activated sludge treatment was carried out in a facility equipped with a sedimentation tank.
All poultry exsanguinations were collected and disposed of by an industrial waste disposal contractor. The oily raw water was pretreated with a sulfate band, caustic soda, and an anionic polymer flocculant, and the pressurized flotation scum was dewatered with a screw press, and the dewatered cake was entrusted to disposal. The commissioned amount of dewatered cake was 960 tons per year. Further, the water quality after the wastewater treatment was 12 ppm for BOD, 20 ppm for COD, 0.1 ppm for n-Hex, and 40 ppm for TN.
[0035]
Example 2
Treated wastewater from chemical manufacturing plants.
The wastewater is a concentrated wastewater with a BOD of 8400 ppm, a COD of 4500 ppm and a TN of 682 ppm of 2.4 tons / H on average, a lean wastewater with a BOD of 260 ppm, COD of 130 ppm and a total nitrogen content of 34 ppm on average of 19 tons / H. Each is discharged.
The concentrated waste liquid treatment equipment (AR) has a capacity of 100 m. ³ And volume 70m ³ Anaerobic treatment part 1a with a capacity of 100 m ³ And volume 70m ³ And an aerobic processing unit 2a.
In addition, the device (BR) for lean wastewater treatment has a capacity of 200 m. ³ Two anaerobic treatment parts 1b and a capacity of 200m ³ Has two aerobic processing units 2b.
[0036]
The concentrated waste liquid is returned to the concentrated waste liquid treatment apparatus (AR) and fed into the anaerobic treatment section 1a together with 0.2 ton / H of sludge, and then subjected to anaerobic treatment. The aerobic treatment was repeated twice. The anaerobic treatment time was 1.2 hours, and the aerobic treatment time was 4 hours.
Thereafter, the wastewater is fed into the anaerobic treatment section 1b of the lean wastewater treatment apparatus (BR) together with the diluted wastewater to perform anaerobic treatment, and then transferred to the aerobic treatment section 2b for aerobic treatment, and anaerobic / aerobic treatment is repeated twice. Was. The anaerobic treatment time was 1.1 hours, and the aerobic treatment time was 3.5 hours.
[0037]
The treated water is separated from the activated sludge using the sedimentation tank 3, and the discharged water is taken out. .
The water quality of the effluent was 13 ppm for BOD, 9 ppm for COD, and 5 ppm for TN. The dehydrated cake was 0.1 ton / H.
[0038]
Comparative Example 2
The wastewater having the water quality and the amount to be treated in the examples was subjected to wastewater treatment only by aerobic treatment.
Wastewater treatment equipment has a capacity of 200m ³ And volume 370m ³ And an aerobic treatment tank.
The concentrated waste liquid and the dilute wastewater were mixed according to the discharge amount and treated in the aerobic treatment tank. The quality of the treated effluent was 13 ppm BOD, 10 ppm COD, and 41 ppm TN. The weight of the dehydrated cake was 0.4 tons / H.
[0039]
Example 3
The wastewater discharged from the miso brewery was treated.
In the wastewater, 1 ton / day of soybean broth waste liquid and 50 ton / day of rice and soup broth are discharged as concentrated waste liquid. This concentrated waste liquid has a BOD of 3500 ppm, a COD of 1800 ppm, and a TN of 300 ppm.
Also, 1000 tons / day of diluted wastewater with a BOD of 400 ppm, a COD of 250 ppm, and a TN of 15 ppm are emitted.
The concentrated waste liquid treatment equipment (AR) has a capacity of 20m. ³ Anaerobic treatment part 1a, volume 60m ³ Aerobic processing unit 2a.
In addition, the device (BR) for lean wastewater treatment has a capacity of 100 m. ³ Anaerobic treatment part 1b and capacity 400m ³ Aerobic processing unit 2b.
[0040]
The concentrated waste liquid is returned to the concentrated waste liquid treatment device (AR) and put into the anaerobic treatment section 1a together with the sludge at 8 tons / H. The anaerobic treatment time is 2 hours, and the aerobic treatment time is 6 hours. Was repeated twice.
Thereafter, the wastewater is fed into the anaerobic treatment section 1b of the lean wastewater treatment apparatus (BR) together with the diluted wastewater to perform anaerobic treatment, and then transferred to the aerobic treatment section 2b for aerobic treatment, and anaerobic / aerobic treatment is repeated twice. Was. The anaerobic treatment time was 2 hours, and the aerobic treatment time was 5 hours.
[0041]
The treated water is separated from the activated sludge using the sedimentation tank 3, and the discharged water is taken out. .
The water quality of the effluent was 8 ppm for BOD, 19 ppm for COD, and 1 ppm or less for TN. The weight of the dehydrated cake was 1 ton / day.
[0042]
Comparative Example 3
The volume of wastewater discharged from the miso brewery in Example 3 was 1000 m ³ Treated in aeration tank. In this case, the quality of the treated effluent was 8 ppm BOD, 20 ppm COD, and 5 ppm TN. The weight of the dehydrated cake was 4 tons / day.
[0043]
【The invention's effect】
The wastewater treatment method of the present invention is provided with an activated sludge treatment apparatus for treating the concentrated waste liquid and the diluted wastewater, respectively, and after the concentrated waste liquid is treated with the activated sludge, is mixed with the diluted wastewater to perform the activated sludge treatment. It becomes easier to acclimatize, less likely to cause bulking, and improves wastewater treatment capacity. Further, the amount of generated sludge can be reduced.
[0044]
Further, in the above wastewater treatment method, the sludge generated from the lean wastewater treatment is used as return sludge, so that the activated sludge cells are more easily acclimated.
[0045]
In the wastewater treatment method, the anaerobic / aerobic treatment conditions in the activated sludge treatment apparatus (AR) are such that the anaerobic treatment time ranges from 0.5 to 6 hours and the aerobic treatment time ranges from 1 to 10 hours. Since the aerobic treatment is performed once or a plurality of times, the volume of the entire wastewater treatment apparatus can be reduced.
[Brief description of the drawings]
FIG. 1 is a flow sheet of a wastewater treatment method.
FIG. 2 is another flow sheet of the wastewater treatment method.
FIG. 3 is a sectional view of a microorganism reaction tank.
[Explanation of symbols]
1 Anaerobic treatment section
2 Aerobic processing unit
3 Sedimentation tank
4 liquid circulation pump
5 liquid switching valve
6 Return sludge

Claims

In a wastewater treatment method for treating a concentrated wastewater and a diluted wastewater,
An activated sludge treatment device (AR) for treating the concentrated waste liquid and an activated sludge treatment device (BR) for treating the dilute wastewater are provided, respectively.
Performing an anaerobic / aerobic treatment on the concentrated waste liquid in the activated sludge treatment device (AR); A process for performing anaerobic / aerobic treatment together with lean wastewater.

After the anaerobic / aerobic treatment in the activated sludge treatment device (BR), the activated sludge is separated and returned to the activated sludge treatment device (AR), or the activated sludge treatment device (AR) and the activated sludge treatment device 2. The wastewater treatment method according to claim 1, further comprising a step of returning to both the activated sludge treatment apparatus and the activated sludge treatment apparatus (BR).

In a wastewater treatment method for treating a concentrated wastewater and a diluted wastewater,
An activated sludge treatment device (AR) for treating the concentrated waste liquid, and an activated sludge treatment device (BR) for treating the dilute wastewater,
A step of subjecting the concentrated waste liquid to anaerobic / aerobic treatment in the activated sludge treatment apparatus (AR), and separating the activated sludge after the anaerobic / aerobic treatment and returning the activated sludge to the activated sludge treatment apparatus (AR); Return to the activated sludge treatment device (BR), or return to both the activated sludge treatment device (AR) and the activated sludge treatment device (BR), and separate the liquid from which activated sludge was separated. Returning to an activated sludge treatment apparatus (BR).

The anaerobic / aerobic treatment conditions in the activated sludge treatment apparatus (AR) are such that the anaerobic treatment time is 0.5 to 6 hours, the aerobic treatment time is 1 to 10 hours, and the anaerobic / aerobic treatment is performed once or The wastewater treatment method according to claim 1 or 3, wherein the method is performed a plurality of times.

The anaerobic / aerobic treatment conditions in the activated sludge treatment apparatus (BR) are such that the anaerobic treatment time is 0.5 to 6 hours, and the aerobic treatment time is 1 to 10 hours. The wastewater treatment method according to claim 1 or 3, wherein the treatment is performed at 2 to 20 times the amount of the diluted wastewater.