JP4092848B2

JP4092848B2 - Waste water treatment equipment

Info

Publication number: JP4092848B2
Application number: JP2000095071A
Authority: JP
Inventors: 一彦能登
Original assignee: Hitachi Plant Technologies Ltd
Current assignee: Hitachi Ltd
Priority date: 2000-03-30
Filing date: 2000-03-30
Publication date: 2008-05-28
Anticipated expiration: 2020-03-30
Also published as: JP2001276885A

Description

【０００１】
【発明の属する技術分野】
本発明は、廃水処理装置に係り、特に、廃水中の有機物とリンの同時除去、或いは廃水中の有機物とリンと窒素の同時除去を行う廃水処理装置に関する。
【０００２】
【従来の技術】
廃水中からの有機物とリンの除去を、ろ過による固液分離と活性汚泥を用いた生物学的処理の組み合わせにより行う場合、廃水中の濁質成分をろ過装置でろ過した後、ろ過水を生物反応装置の嫌気槽に流入させる。嫌気槽では、ろ過水と活性汚泥が混合してリン蓄積菌がリンを放出する。この際に、リン蓄積菌はろ過水中の有機物をリンを放出のための栄養源として利用する。尚、リン蓄積菌のリン放出にとって有効とされている有機物成分は、主に有機酸（溶存態有機物）であるといわれており、有機物を酸発酵することにより生成される。
【０００３】
続いて、嫌気槽から流出した汚泥混合液は好気槽において、リン蓄積菌は廃水中のリンを前記放出した以上に過剰摂取すると共に、残存する有機物成分の酸化分解が行われる。これにより、廃水中からの有機物とリンとが同時除去される。
【０００４】
ところで、ろ過装置として、廃水をろ材層で強制ろ過させることにより廃水中の濁質成分の除去率を高めた高速ろ過装置を用いた場合には、沈殿池のように濁質成分を自然沈降させて固液分離する場合に比べて、ろ過速度が速く、且つ濁質成分の除去率を著しく高めることができる。これにより、生物反応装置における有機物の酸化分解の負荷を小さくすることができると共に、雨天時に廃水水量が増加して生物反応装置へ受け入れ可能な水量を超えた場合には、廃水の一部を高速ろ過装置でろ過しただけで生物反応装置を経由せずに放流できるという長所がある。更には、ろ過装置の敷地面積を小さくできるので、都会等のように大きな敷地面積を確保できない場所にも設置できるという長所もある。
【０００５】
【発明が解決しようとする課題】
しかしながら、高速ろ過装置は、上記した色々な長所がある反面、雨天時の水量増加等により廃水中の有機物濃度が小さくなる方向に変動した場合には、濁質成分の除去率が高いことにより、嫌気槽でのリン蓄積菌の栄養源として利用される有機物が十分に補給されないという問題がある。更には、高速ろ過装置はろ過速度が早く高速ろ過装置内での滞留時間が短いために、高速ろ過装置内で有機酸が生成されにくいという問題もある。
【０００６】
また、廃水中の有機物とリンと窒素を同時除去するための廃水処理装置の場合にも、脱窒処理において脱窒菌が有機物を栄養源とすることから、高速ろ過装置で廃水中の有機物が減少した場合には同様の問題が生じる。
【０００７】
本発明は、このような事情に鑑みてなされたもので、高速ろ過装置のメリットを生かしながら、廃水中の有機物、リン、或いは廃水中の有機物、リン、窒素を効率良く除去することのできる廃水処理装置を提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明の請求項１は前記目的を達成するために、流入する廃水中の有機物とリンの除去を行う廃水処理装置において、嫌気槽と好気槽を有し生物学的な処理を行う生物反応装置と、前記生物反応装置の前段に設けられ、前記廃水をろ材層で強制ろ過させることにより前記廃水中の濁質成分の除去率を高めた高速ろ過装置と、前記ろ材層を前記流入する廃水で逆洗するろ材逆洗系路と、前記ろ材層を逆洗して発生する逆洗排泥を滞留させる逆洗排泥槽と、前記逆洗排泥槽内の逆洗排泥を攪拌する攪拌手段と、前記逆洗排泥槽で攪拌・滞留を行った逆洗排泥を前記嫌気槽に投入する送液ポンプと、前記嫌気槽に設けられたリン濃度測定手段の測定結果に基づいて前記送液ポンプのＯＮ−ＯＦＦを行う手段と、を備えたことを特徴とする。
【０００９】
本発明の請求項１によれば、高速ろ過装置のろ材層の逆洗により発生する逆洗排泥に含まれる有機物を、生物反応装置の嫌気槽でのリン蓄積菌のリン放出のための栄養源として利用するに際して、高速ろ過装置のろ材層を逆洗する逆洗水として流入廃水を用いると共に、逆洗排泥を逆洗排泥槽で攪拌しながら滞留させて有機酸生成量を高めた逆洗汚泥を嫌気槽に投入するようにした。これにより、高速ろ過装置から生物反応装置に有機物含有量の低いろ過水が供給される場合でも、嫌気槽でのリン蓄積菌のリン放出を安定して行うことができるので、高速ろ過装置のメリットを生かしながら、有機物とリンの除去を効果的に行うことができる。
【００１０】
また、本発明の請求項２は前記目的を達成するために、流入する廃水中の有機物とリンと窒素の除去を行う廃水処理装置において、嫌気槽、無酸素槽及び好気槽を有し生物学的な処理を行う生物反応装置と、前記生物反応装置の前段に設けられ、前記廃水をろ材層で強制ろ過させることにより前記廃水中の濁質成分の除去率を高めた高速ろ過装置と、前記ろ材層を前記流入する廃水で逆洗するろ材逆洗系路と、前記ろ材層を逆洗して発生する逆洗排泥を滞留させる逆洗排泥槽と、前記逆洗排泥槽内の逆洗排泥を攪拌する攪拌手段と、前記逆洗排泥槽で攪拌・滞留を行った逆洗排泥のうちの上澄み液を前記嫌気槽に投入する送液ポンプと、前記逆洗排泥槽で攪拌・滞留を行った逆洗排泥のうちの沈降汚泥を前記無酸素槽に投入する送泥ポンプと、前記嫌気槽に設けられたリン濃度測定手段の測定結果に基づいて前記送液ポンプをＯＮ−ＯＦＦさせる手段と、前記無酸素槽に設けられたＮＯ _３ −Ｎ濃度測定手段の測定結果に基づいて前記送泥ポンプのＯＮ−ＯＦＦを行う手段と、を備えたことを特徴とする。
【００１１】
本発明の請求項２は、廃水中の有機物、リン、窒素を除去するように構成したもので、逆洗排泥槽で滞留・攪拌させた逆洗排泥のうち、生成された有機酸（溶存態有機物）を多く含む上澄み液を嫌気槽に供給し、逆洗排泥のうちの沈殿汚泥（固形有機物）を無酸素槽に供給するようにしたものである。これにより、高速ろ過装置から生物反応装置に有機物含有量の低いろ過水が供給される場合でも、嫌気槽でのリン蓄積菌のリン放出を安定して行うことができるだけでなく、無酸素槽での脱窒反応を促進させることができるので、高速ろ過装置のメリットを生かしながら、有機物とリンと窒素の除去を効果的に行うことができる。
【００１２】
【発明の実施の形態】
以下添付図面に従って、本発明の廃水処理装置の好ましい実施の形態について詳説する。
【００１３】
図１は、本発明の廃水処理装置の構成を示したものであり、廃水中の有機物、リン、窒素を除去する例で説明する。
【００１４】
図１に示すように、廃水処理装置１０は、主として、高速ろ過装置１２と生物反応装置１４と固液分離槽１６と逆洗排泥槽１８とで構成される。
【００１５】
高速ろ過装置１２は、ろ過槽２０内の中段に多数のろ材から成るろ材層２２を設け、原水管２４からろ過槽２０内に流入させた廃水を上向流（図１の例）又は下向流でろ材層２２を通過させることにより強制ろ過し、これにより廃水中の濁質成分を濁質とろ材との間、或いは濁質相互間のふるい分け作用により捕捉するものである。これにより、ろ過速度を向上させることができると共に濁質成分の除去率を著しく高めることができる。
【００１６】
また、ろ過槽２０の底部全体には、エアノズル２１が設けられエア配管２３を介してブロア２５に接続される。そして、高速ろ過装置１２のろ材層２２の逆洗運転を行う場合には、原水の供給を停止し、エアノズル２１から洗浄エアをろ材層２２に向けて噴出してろ材を攪拌しながら、ろ材層２２に付着した濁質成分を逆洗する。また、ろ材層２２を逆洗してろ過槽２０の底部に溜まった逆洗排泥は、送泥管３０を介して逆洗排泥槽１８に送られる。また、原水管２４には、凝集剤添加装置３２のバルブ付き添加管３４が接続される。
【００１７】
生物反応装置１４は、嫌気槽３６、無酸素槽３８、好気槽４０の順に配設された３槽から構成され、廃水中の有機物、リン、窒素を活性汚泥により生物学的に除去する。高速ろ過装置１２でろ過されたろ過水は、ろ過水配管４２を介して嫌気槽３６に送られる。ろ過水配管４２には、ろ過しただけで放流するためのバルブ付き放流管４４が分岐される。また、好気槽４０から排出された処理水の一部は、硝化循環管４６を介して無酸素槽３８の入口に循環されると共に、残りの処理水は固液分離槽１６に送られて固液分離される。固液分離槽１６で固液分離された上澄み液は処理水管４８から系外に排出される。一方、固液分離槽１６の底部に沈降した活性汚泥は返送汚泥管５０を介して嫌気槽３６の入口に戻されると共に、余剰汚泥は引抜管５２を介して系外に引き抜かれる。
【００１８】
逆洗排泥槽１８内には、攪拌機５６が設けられ、逆洗排泥槽１８の上部と嫌気槽３６とが分離水管５８を介して接続されると共に、逆洗排泥槽１８の底部と無酸素槽３８とが沈降排泥管６０を介して接続される。
【００１９】
また、嫌気槽３６には、嫌気槽３６内のリン濃度を測定する自動リン測定計６２が設けられ、測定されたリン濃度に基づいて分離水管５８に設けられた送液ポンプ６４のＯＮ−ＯＦＦが行われる。また、無酸素槽３８には、無酸素槽３８内のＮＯ₃ - Ｎ濃度を測定する自動ＮＯ₃ - Ｎ測定計６６が設けられ、測定されたＮＯ₃ - Ｎに基づいて沈降排泥管６０に設けられた送泥ポンプ６８のＯＮ−ＯＦＦが行われる。尚、自動リン測定計６２及び自動ＮＯ₃ - Ｎ測定計６６は、取水口６２Ａ、６６Ａからろ過器６２Ｂ、６６Ｂを介して取水する。
【００２０】
次に、上記の如く構成された廃水処理装置１０の作用について説明する。
【００２１】
原水管２４から高速ろ過装置１２に流入する廃水は、ろ過槽２０内を上向流となって流れ、ろ材層２２により廃水中の濁質成分が除去される。この場合、ろ過槽２０に流入する廃水中に、凝集剤添加装置３２から必要に応じて凝集剤を添加する。例えば、合流式下水道の場合には、雨天時に雨水が下水管渠に流入し、原水管２４から高速ろ過装置１２に流入する流入量が晴天時の２〜３倍に増加するので、このような場合に凝集剤を添加することにより、濁質成分の除去能力を高め、処理水量を凝集剤を添加しない場合の２〜３倍に高めることができる。但し、生物反応装置１４で処理可能な廃水量には限界があるので、雨天時のように流入水量が大幅に増加する場合には、晴天時の流入水量の１．５倍までの水量を生物反応装置１４に送水し、それを超えるろ過水は放流管４４から簡易放流水としてそのまま系外に放流する。
【００２２】
次に、高速ろ過装置１２でろ過されたろ過水は、生物反応装置１４の嫌気槽３６に流入する。嫌気槽３６では嫌気性状態下において、活性汚泥に含まれるリン蓄積菌が有機物を栄養源として取り込むと共に、菌体内に蓄積したリンを吐き出す。
【００２３】
次に、嫌気槽３６内の廃水と活性汚泥の混合液は、無酸素槽３８、好気槽４０の順に流れると共に、好気槽４０から排出された処理水の一部が硝化循環管４６を介して無酸素槽３８に循環される。無酸素槽３８では無酸素状態（硝酸態窒素のような酸化態窒素は存在する）の下で、活性汚泥に含まれる脱窒菌が有機物を栄養源として廃水中の硝酸態窒素或いは亜硝酸態窒素を脱窒反応により窒素ガス化して除去すると共に、リン蓄積菌は嫌気槽３６で吐き出したリンの一部分を摂取する。一方、好気槽４０では好気状態下において、活性汚泥に含まれる硝化菌が廃水中のアンモニア態窒素を硝酸態窒素或いは亜硝酸態窒素に酸化すると共に、リン蓄積菌が廃水中のリンを前記吐き出した以上に過剰摂取する。この場合、好気槽４０には活性汚泥の他に、硝化菌を包括固定したペレットを投入すると硝化効率を高めることができる。また、好気槽では、残存する有機物成分の酸化分解が行われる。これにより、廃水中の有機物、リン、窒素が除去される。
【００２４】
高速ろ過装置１２は、ろ過を継続していると、ろ材層２２に濁質成分が付着してろ過効率が低下するので、ろ材層２２を定期的に逆洗する必要がある。逆洗の操作は、原水管２４からの原水の供給を停止し、エアノズル２１から洗浄エアをろ材層２２に向けて噴出することでろ材を攪拌してろ材層２２を逆洗する。逆洗により発生する逆洗排泥は、送泥管３０を介して逆洗排泥槽１８に送られる。この場合、生物反応装置１４に対して高速ろ過装置１２を複数台並列に配設して、高速ろ過装置１２のろ過運転と逆洗運転とを切り換えると共に、それぞれの高速ろ過装置１２に逆洗排泥槽１８を設けることにより逆洗排泥槽１８での滞留・攪拌時間を十分にとれるようにするとよい。
【００２５】
ところで、上記した廃水中の有機物、リン、窒素の除去過程において、生物反応装置１４の前段に、廃水中の濁質成分の除去効率の高い高速ろ過装置１２を配設した場合には、除去される濁質成分中に有機物が含有されるので、生物反応装置１４の嫌気槽３６や無酸素槽３８におけるリン蓄積菌や脱窒菌の栄養源として利用される有機物が十分に補給されない場合ある。これにより、嫌気槽３６でのリン放出が安定しなくなったり、無酸素槽３８での脱窒反応が低下したりするという問題がある。即ち、雨天時のように高速ろ過装置１２に流入する廃水に凝集剤を添加した場合には、ろ過による濁質成分の除去率は添加しない場合（晴天時）に比べて良くなることから、生物反応装置１４へ流入するろ過水中の有機物含有量が低下する。このような降雨による流入量の増加時や、嫌気槽３６において一時的にリン放出量の低下がある場合には、逆洗排泥槽１８で攪拌しながら一定時間滞留させた逆洗排泥のうちの上澄み液を嫌気槽３６に供給すると共に、逆洗排泥のうちの沈殿汚泥を無酸素槽３８に供給する。即ち、逆洗排泥槽１８では、流入廃水中の活性度の高い微生物と逆洗排泥とを攪拌により接触させながら一定時間滞留させる。図２は、逆洗排泥槽１８における滞留時間と有機酸（ＶＦＡ）の生成量を、攪拌の有り無しで比較したものであるが、この結果から分かるように、逆洗排泥を逆洗排泥槽１８内で単に滞留させるよりも攪拌をしながら滞留させることにより、有機酸の生成量を顕著に高めることができる。また、逆洗排泥槽１８で生成された有機酸は低分子化して溶存性が大きくなるので、逆洗排泥槽１８の上澄み水側に多く存在する。従って、上澄み水を嫌気槽３６に送ることにより、リン蓄積菌の栄養源としてより適切な有機物を供給することができる。また、ろ過水中の有機物含有量が少ない場合には、通常、流入廃水の有機物・窒素比率（ＢＯＤ／Ｎ）が低く、無酸素槽３８における脱窒反応に必要な有機物量が不足するので、逆洗排泥槽１８の底部に沈降する沈降汚泥を無酸素槽３８に供給する。脱窒反応に必要な有機物は固形有機物も有効であり、有機酸にこだわることはない。これにより、逆洗により発生した逆洗排泥を嫌気槽３６と無酸素槽３８の栄養源としてより適切な形に変えて有効利用することができる。
【００２６】
但し、逆洗排泥槽１８からの有機物の供給量を、嫌気槽３６のリン蓄積菌や無酸素槽３８の脱窒菌が必要とする以上に供給すると、処理水中の有機物残存量が多くなるという弊害がある。従って、嫌気槽３６に槽内のリン濃度を自動測定する自動リン測定計６２を設けると共に、無酸素槽３８に槽内のＮＯ₃ - Ｎを自動測定する自動ＮＯ₃ - Ｎ測定計６６を設け、それぞれの測定計６２、６６の測定値に応じて逆洗排泥槽１８からの分離水や沈降汚泥の供給タイミングを制御すると良い。これにより、嫌気槽３６と無酸素槽３８に適量の有機物を供給することができる。また、別の方法としては、雨天時のように、流入水量が増加することでろ過水中の有機物が低下することを利用して、原水管２４に流入水量を測定する流量計を設け、逆洗排泥槽１８からの分離水や沈降汚泥の供給タイミングを流入水量に応じて制御してもよい。
【００２７】
図３は、廃水中の有機物とリンを除去する場合の構成で、生物反応装置１４から無酸素槽３８を除いた嫌気槽３６と好気槽４０とで構成すると共に、窒素除去に関係するラインを除去したものであり、その他の構成は図２と同様である。
【００２８】
【発明の効果】
以上説明したように、本発明の廃水処理装置によれば、ろ過速度が速く、且つ濁質成分の除去率を著しく高めることができるという高速ろ過装置のメリットを生かしながら、廃水中の有機物とリン、或いは廃水中の有機物とリンと窒素を効率良く且つ安定的に除去することができる。
【図面の簡単な説明】
【図１】本発明の廃水処理装置であり、廃水中の有機物とリンと窒素を除去する場合の構成図
【図２】逆洗排泥滞留槽での攪拌・滞留時間と有機酸の生成量の関係を示した説明図
【図３】本発明の廃水処理装置であり、廃水中の有機物とリンを除去する場合の構成図
【符号の説明】
１０…廃水処理装置、１２…高速ろ過装置、１４…生物反応装置、１６…固液分離槽、１８…逆洗排泥槽、２０…ろ過槽、２１…エアノズル、２２…ろ材層、２４…原水管、３０…送泥管、３２…凝集剤添加装置、３６…嫌気槽、３８…無酸素槽、４０…好気槽、４６…硝化循環管、５０…返送汚泥管、５６…攪拌機、５８…分離水管、６０…沈降排泥管、６２…自動リン測定計、６４…送液ポンプ、６６…自動ＮＯ₃ - Ｎ測定計[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wastewater treatment apparatus, and more particularly, to a wastewater treatment apparatus that performs simultaneous removal of organic substances and phosphorus in wastewater or simultaneous removal of organic substances, phosphorus, and nitrogen in wastewater.
[0002]
[Prior art]
When organic matter and phosphorus are removed from wastewater by a combination of solid-liquid separation by filtration and biological treatment using activated sludge, turbid components in the wastewater are filtered with a filtration device, and then the filtered water is Let it flow into the anaerobic tank of the reactor. In the anaerobic tank, filtered water and activated sludge are mixed and phosphorus accumulating bacteria release phosphorus. At this time, the phosphorus accumulating bacteria use the organic matter in the filtered water as a nutrient source for releasing phosphorus. In addition, it is said that the organic substance component effective for phosphorus release of phosphorus accumulating bacteria is mainly an organic acid (dissolved organic substance), and is produced by acid fermentation of the organic substance.
[0003]
Subsequently, in the aerobic tank, the sludge mixed solution flowing out from the anaerobic tank is excessively consumed by the phosphorus accumulating bacteria more than the release of phosphorus in the wastewater, and the remaining organic components are oxidatively decomposed. Thereby, the organic matter and phosphorus from wastewater are removed simultaneously.
[0004]
By the way, when using a high-speed filtration device that increases the removal rate of turbidity components in wastewater by forcibly filtering wastewater through a filter medium layer, the turbidity components are allowed to settle naturally like a sedimentation basin. Compared with the case of solid-liquid separation, the filtration rate is high and the removal rate of turbid components can be remarkably increased. This can reduce the burden of oxidative decomposition of organic matter in the bioreactor, and if the amount of wastewater increases during rainy weather and exceeds the amount that can be accepted by the bioreactor, a part of the wastewater is There is an advantage that it can be discharged without passing through a biological reaction device just by filtering with a filtration device. Furthermore, since the site area of the filtration device can be reduced, there is also an advantage that it can be installed in a place where a large site area cannot be secured such as in a city.
[0005]
[Problems to be solved by the invention]
However, the high-speed filtration device has various advantages as described above, but when the organic matter concentration in the wastewater decreases due to an increase in the amount of water during rainy weather, the removal rate of turbid components is high. There is a problem that organic matter used as a nutrient source for phosphorus-accumulating bacteria in an anaerobic tank is not sufficiently replenished. Furthermore, since the high-speed filtration device has a high filtration rate and a short residence time in the high-speed filtration device, there is also a problem that an organic acid is hardly generated in the high-speed filtration device.
[0006]
Also, in the case of wastewater treatment equipment for simultaneous removal of organic matter, phosphorus and nitrogen in wastewater, denitrification bacteria use organic matter as a nutrient source in the denitrification treatment, so organic matter in wastewater is reduced with a high-speed filtration device. In this case, the same problem occurs.
[0007]
The present invention has been made in view of such circumstances, and waste water that can efficiently remove organic matter, phosphorus, or organic matter, phosphorus, nitrogen in waste water while taking advantage of the high-speed filtration device. An object is to provide a processing apparatus.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, claim 1 of the present invention is a wastewater treatment apparatus for removing organic matter and phosphorus in inflowing wastewater, and a biological reaction having an anaerobic tank and an aerobic tank for biological treatment. A high-speed filtration device that is provided in a preceding stage of the bioreactor and forcibly filters the wastewater through a filter medium layer to increase the removal rate of turbid components in the wastewater, and the wastewater that flows into the filter medium layer The backwash drainage path in the backwash waste mud tank is agitated, the backwash drainage tank in which the backwash waste mud generated by backwashing the filter material layer is backwashed, and the backwash waste mud in the backwash waste mud tank are stirred. Based on the measurement results of the stirring means, the liquid feed pump that feeds the backwash wastewater that has been stirred and retained in the backwash waste mud tank into the anaerobic tank, and the phosphorus concentration measurement means provided in the anaerobic tank And a means for turning on and off the liquid feed pump .
[0009]
According to claim 1 of the present invention, the organic matter contained in the backwash waste mud generated by backwashing the filter medium layer of the high-speed filter is used for nutrition for phosphorus release of phosphorus accumulating bacteria in the anaerobic tank of the bioreactor. When using as a source, inflow wastewater was used as backwash water to backwash the filter medium layer of the high-speed filtration device, and the backwash waste mud was retained while stirring in the backwash waste mud tank to increase the amount of organic acid produced. Backwash sludge was put into the anaerobic tank. As a result, even when filtered water with a low organic matter content is supplied from the high-speed filtration device to the biological reaction device, phosphorus release of the phosphorus accumulating bacteria in the anaerobic tank can be performed stably, so the merit of the high-speed filtration device It is possible to effectively remove organic substances and phosphorus while taking advantage of the above.
[0010]
According to a second aspect of the present invention, there is provided a wastewater treatment apparatus for removing organic matter, phosphorus and nitrogen in an inflowing wastewater, and an anaerobic tank, an anaerobic tank and an aerobic tank. A biological reaction apparatus that performs a biological treatment, a high-speed filtration apparatus that is provided in the preceding stage of the biological reaction apparatus, and that increases the removal rate of turbid components in the wastewater by forcibly filtering the wastewater through a filter medium layer; A filter medium backwash system for backwashing the filter medium layer with the inflowing waste water, a backwash drainage tank for retaining backwash waste mud generated by backwashing the filter medium layer, and the backwash waste mud tank a stirring means for stirring the backwash waste sludge of a liquid feed pump for introducing the supernatant of the backwash waste sludge which was stirred and residence in the backwash discharge sludge tank to said anaerobic tank, said backwash discharge and Okudoro pump to inject sedimentation sludge of the backwash waste sludge which was stirred and residence with mud tank to the anoxic tank A means for ON-OFF of the liquid feed pump on the basis of the measurement results of the phosphorus concentration measurement means provided in said anaerobic tank, based on the measurement results of the NO 3 _-N concentration measuring means provided in the anoxic tank Means for turning on and off the mud pump .
[0011]
Claim 2 of the present invention is configured to remove organic matter, phosphorus, and nitrogen in wastewater. Among the backwash waste mud retained and stirred in the backwash waste mud tank, the generated organic acid ( The supernatant liquid containing a large amount of dissolved organic matter) is supplied to the anaerobic tank, and the precipitated sludge (solid organic matter) of the backwash waste mud is supplied to the anoxic tank. As a result, even when filtered water with a low organic matter content is supplied from the high-speed filtration device to the biological reaction device, it is possible not only to stably release phosphorus of phosphorus-accumulating bacteria in the anaerobic tank, but also in an anoxic tank. Since the denitrification reaction can be promoted, organic substances, phosphorus and nitrogen can be effectively removed while taking advantage of the high-speed filtration device.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiments of the wastewater treatment apparatus of the present invention will be described in detail below with reference to the accompanying drawings.
[0013]
FIG. 1 shows the configuration of the wastewater treatment apparatus of the present invention, and will be described with an example of removing organic substances, phosphorus, and nitrogen in wastewater.
[0014]
As shown in FIG. 1, the wastewater treatment apparatus 10 is mainly composed of a high-speed filtration device 12, a biological reaction device 14, a solid-liquid separation tank 16, and a backwash waste mud tank 18.
[0015]
The high-speed filtration device 12 is provided with a filter medium layer 22 composed of a large number of filter media in the middle stage in the filter tank 20, and the wastewater that has flowed into the filter tank 20 from the raw water pipe 24 flows upward (example in FIG. 1) or downward. The forced filtration is performed by passing through the filter medium layer 22 in a flow, whereby the turbid component in the wastewater is captured by the sieving action between the turbid substance and the filter medium or between the turbid substances. Thereby, the filtration rate can be improved and the removal rate of turbid components can be remarkably increased.
[0016]
An air nozzle 21 is provided on the entire bottom of the filtration tank 20 and is connected to a blower 25 via an air pipe 23. And when performing the backwash operation of the filter medium layer 22 of the high-speed filter 12, the supply of raw water is stopped, and the filter medium layer is stirred while jetting the cleaning air from the air nozzle 21 toward the filter medium layer 22 and stirring the filter medium. The turbid component adhering to 22 is back-washed. Further, the backwashing mud accumulated in the bottom of the filtration tank 20 by backwashing the filter medium layer 22 is sent to the backwashing mud tank 18 through the mud pipe 30. Further, an addition pipe 34 with a valve of a flocculant addition device 32 is connected to the raw water pipe 24.
[0017]
The biological reaction apparatus 14 is composed of three tanks arranged in the order of an anaerobic tank 36, an oxygen-free tank 38, and an aerobic tank 40, and biologically removes organic matter, phosphorus, and nitrogen in wastewater by activated sludge. The filtered water filtered by the high-speed filtration device 12 is sent to the anaerobic tank 36 through the filtered water pipe 42. The filtered water pipe 42 is branched with a discharge pipe 44 with a valve for discharging it just by filtering. A part of the treated water discharged from the aerobic tank 40 is circulated to the inlet of the anoxic tank 38 via the nitrification circulation pipe 46 and the remaining treated water is sent to the solid-liquid separation tank 16. Solid-liquid separation. The supernatant liquid separated from the solid-liquid separation tank 16 is discharged from the treated water pipe 48 to the outside of the system. On the other hand, the activated sludge that has settled at the bottom of the solid-liquid separation tank 16 is returned to the inlet of the anaerobic tank 36 through the return sludge pipe 50, and the excess sludge is drawn out of the system through the drawing pipe 52.
[0018]
A stirrer 56 is provided in the backwashing mud tank 18, and the upper part of the backwashing mud tank 18 and the anaerobic tank 36 are connected via a separation water pipe 58, and the bottom of the backwashing mud tank 18 The anaerobic tank 38 is connected via a sedimentation mud pipe 60.
[0019]
Further, the anaerobic tank 36 is provided with an automatic phosphorus measuring meter 62 for measuring the phosphorus concentration in the anaerobic tank 36, and ON / OFF of the liquid feed pump 64 provided in the separation water pipe 58 based on the measured phosphorus concentration. Is done. The oxygen-free tank 38 is provided with an automatic NO ₃ -N measuring meter 66 for measuring the NO ₃ -N concentration in the oxygen-free tank 38, and the sedimentation and drainage pipe 60 is based on the measured NO ₃ -N. ON / OFF of the mud feed pump 68 provided in is performed. The automatic phosphorus meter 62 and the automatic NO ₃ −N meter 66 take water from the water intakes 62A and 66A through the filters 62B and 66B.
[0020]
Next, the operation of the wastewater treatment apparatus 10 configured as described above will be described.
[0021]
Waste water flowing into the high-speed filtration device 12 from the raw water pipe 24 flows upward in the filtration tank 20, and turbid components in the waste water are removed by the filter medium layer 22. In this case, a flocculant is added to the waste water flowing into the filtration tank 20 from the flocculant addition device 32 as necessary. For example, in the case of a combined sewer, rainwater flows into the sewer pipe during rainy weather, and the amount of inflow flowing from the raw water pipe 24 into the high-speed filtration device 12 is increased two to three times that during fine weather. In some cases, by adding a flocculant, the ability to remove turbid components can be increased, and the amount of treated water can be increased to 2 to 3 times that when no flocculant is added. However, since there is a limit to the amount of wastewater that can be treated by the biological reaction device 14, when the inflow water amount increases significantly during rainy weather, the amount of water up to 1.5 times the inflow water amount during fine weather can be The water that is fed to the reactor 14 and the filtered water that exceeds it is discharged from the discharge pipe 44 as simple discharged water to the outside of the system.
[0022]
Next, the filtrate water filtered by the high-speed filtration device 12 flows into the anaerobic tank 36 of the biological reaction device 14. In the anaerobic tank 36, in an anaerobic state, the phosphorus accumulating bacteria contained in the activated sludge take in organic matter as a nutrient source, and discharge the phosphorus accumulated in the cells.
[0023]
Next, the mixed solution of waste water and activated sludge in the anaerobic tank 36 flows in the order of the anaerobic tank 38 and the aerobic tank 40, and part of the treated water discharged from the aerobic tank 40 passes through the nitrification circulation pipe 46. It is circulated to the anoxic tank 38 through. In the anaerobic tank 38, denitrifying bacteria contained in the activated sludge are used as an nutrient source for nitrate nitrogen or nitrite nitrogen in wastewater under anaerobic conditions (the presence of oxidized nitrogen such as nitrate nitrogen). Is removed by nitrogen gasification by a denitrification reaction, and the phosphorus accumulating bacteria ingest a part of phosphorus exhaled in the anaerobic tank 36. On the other hand, in the aerobic tank 40, the nitrifying bacteria contained in the activated sludge oxidize ammonia nitrogen in the wastewater to nitrate nitrogen or nitrite nitrogen in the aerobic state, and the phosphorus accumulating bacteria convert phosphorus in the wastewater. Take more than you exhale. In this case, in addition to the activated sludge, the aerobic tank 40 can be improved in nitrification efficiency by introducing pellets in which nitrifying bacteria are comprehensively fixed. In the aerobic tank, the remaining organic components are oxidatively decomposed. Thereby, the organic matter, phosphorus, and nitrogen in the wastewater are removed.
[0024]
When the high-speed filtration device 12 continues the filtration, the turbid component adheres to the filter medium layer 22 and the filtration efficiency is lowered. Therefore, the filter medium layer 22 needs to be regularly backwashed. The operation of backwashing stops the supply of the raw water from the raw water pipe 24 and agitates the filter medium by jetting the cleaning air from the air nozzle 21 toward the filter medium layer 22 to backwash the filter medium layer 22. The backwash mud generated by backwashing is sent to the backwash mud tank 18 through the mud pipe 30. In this case, a plurality of high-speed filtration devices 12 are arranged in parallel with respect to the biological reaction device 14 to switch between the filtration operation and the backwash operation of the high-speed filtration device 12, and each high-speed filtration device 12 is backwashed and discharged. By providing the mud tank 18, it is preferable that the residence / stirring time in the backwashing mud tank 18 can be sufficiently taken.
[0025]
By the way, in the process of removing organic matter, phosphorus, and nitrogen in the waste water described above, when the high-speed filtration device 12 having high removal efficiency of turbid components in the waste water is disposed in the front stage of the biological reaction device 14, it is removed. Since organic matter is contained in the turbid component, organic matter used as a nutrient source for phosphorus accumulating bacteria and denitrifying bacteria in the anaerobic tank 36 and anoxic tank 38 of the biological reaction device 14 may not be sufficiently supplied. As a result, there is a problem that phosphorus release in the anaerobic tank 36 becomes unstable, and denitrification reaction in the anaerobic tank 38 decreases. That is, when a flocculant is added to wastewater flowing into the high-speed filtration device 12 during rainy weather, the removal rate of turbid components by filtration is better than when no turbid component is added (when clear weather). The organic matter content in the filtered water flowing into the reactor 14 decreases. When the amount of inflow due to rain increases or when there is a temporary decrease in the amount of phosphorus released in the anaerobic tank 36, the backwash waste mud retained for a certain period of time while stirring in the backwash mud tank 18. The supernatant liquid is supplied to the anaerobic tank 36, and the precipitated sludge of the backwash waste mud is supplied to the anoxic tank 38. That is, in the backwashing mud tank 18, microorganisms having high activity in the inflow wastewater and the backwashing mud are retained for a certain period of time while being brought into contact with stirring. FIG. 2 compares the residence time in the backwashing mud tank 18 and the amount of organic acid (VFA) produced with and without stirring. As can be seen from this result, the backwashing mud is backwashed. The production amount of the organic acid can be remarkably increased by staying with stirring rather than simply staying in the mud tank 18. Moreover, since the organic acid produced | generated in the backwashing waste mud tank 18 becomes low molecular weight and solubility becomes large, many exist in the supernatant water side of the backwashing waste mud tank 18. FIG. Therefore, by sending the supernatant water to the anaerobic tank 36, more appropriate organic matter can be supplied as a nutrient source for phosphorus-accumulating bacteria. In addition, when the organic matter content in the filtered water is small, the organic matter / nitrogen ratio (BOD / N) of the inflow wastewater is usually low, and the amount of organic matter necessary for the denitrification reaction in the anoxic tank 38 is insufficient. Precipitated sludge that settles at the bottom of the washing and mud tank 18 is supplied to the anoxic tank 38. The organic matter necessary for the denitrification reaction is also effective as a solid organic matter and does not stick to organic acids. Thereby, the backwash waste mud generated by backwashing can be effectively used by changing it to a more appropriate form as a nutrient source for the anaerobic tank 36 and the oxygen-free tank 38.
[0026]
However, if the amount of organic matter supplied from the backwash waste mud tank 18 is more than required by the phosphorus accumulating bacteria in the anaerobic tank 36 or the denitrifying bacteria in the anoxic tank 38, the amount of organic matter remaining in the treated water will increase. There are harmful effects. Accordingly, the anaerobic tank 36 is provided with an automatic phosphorus meter 62 for automatically measuring the phosphorus concentration in the tank, and the oxygen-free tank 38 is provided with an automatic NO ₃ -N meter 66 for automatically measuring NO ₃ -N in the tank. The supply timing of the separated water and the settled sludge from the backwashing mud tank 18 may be controlled according to the measured values of the respective measuring meters 62 and 66. Thereby, an appropriate amount of organic substances can be supplied to the anaerobic tank 36 and the anaerobic tank 38. As another method, a flow meter for measuring the amount of inflow water is provided in the raw water pipe 24 by utilizing the fact that the organic matter in the filtered water decreases as the amount of inflow water increases as in rainy weather, and backwashing is performed. You may control the supply timing of the separation water and sedimentation sludge from the mud tank 18 according to the amount of inflow water.
[0027]
FIG. 3 shows a configuration for removing organic substances and phosphorus in wastewater, which is composed of an anaerobic tank 36 and an aerobic tank 40 excluding the oxygen-free tank 38 from the biological reaction apparatus 14 and a line related to nitrogen removal. The other configurations are the same as in FIG.
[0028]
【The invention's effect】
As described above, according to the wastewater treatment apparatus of the present invention, while taking advantage of the high-speed filtration apparatus that the filtration speed is high and the removal rate of turbid components can be remarkably increased, Alternatively, organic substances, phosphorus, and nitrogen in waste water can be removed efficiently and stably.
[Brief description of the drawings]
FIG. 1 is a block diagram of the wastewater treatment apparatus of the present invention when organic substances, phosphorus and nitrogen are removed from wastewater. FIG. 2 is agitation and residence time in a backwash waste mud retention tank and the amount of organic acid produced. FIG. 3 is a wastewater treatment apparatus according to the present invention, and is a configuration diagram for removing organic matter and phosphorus in wastewater.
DESCRIPTION OF SYMBOLS 10 ... Waste water treatment apparatus, 12 ... High-speed filtration apparatus, 14 ... Biological reaction apparatus, 16 ... Solid-liquid separation tank, 18 ... Backwash waste mud tank, 20 ... Filtration tank, 21 ... Air nozzle, 22 ... Filter material layer, 24 ... Original Water pipe, 30 ... mud pipe, 32 ... flocculant addition device, 36 ... anaerobic tank, 38 ... anoxic tank, 40 ... aerobic tank, 46 ... nitrification circulation pipe, 50 ... return sludge pipe, 56 ... stirrer, 58 ... separating the water pipe, 60 ... sedimentation Haidorokan, 62 ... auto phosphorus meter, 64 ... feeding pump, 66 ... auto NO ₃ - N meter

Claims

In wastewater treatment equipment that removes organic matter and phosphorus in the inflowing wastewater,
A biological reaction apparatus having an anaerobic tank and an aerobic tank for biological treatment;
A high-speed filtration device that is provided in the previous stage of the biological reaction device, and that increases the removal rate of turbid components in the wastewater by forcibly filtering the wastewater through a filter medium layer;
A filter media backwash system for backwashing the filter media layer with the inflowing waste water;
A backwash waste mud tank for retaining backwash waste mud generated by backwashing the filter medium layer;
Agitation means for agitating the backwashing mud in the backwashing mud tank;
The backwash and liquid feed pump for introducing backwash waste sludge which was stirred and retained in the anaerobic tank with waste mud tank, the liquid feed pump on the basis of the measurement results of the phosphorus concentration measurement means provided in said anaerobic tank Means for turning on and off;
A wastewater treatment apparatus characterized by comprising:

In wastewater treatment equipment that removes organic matter, phosphorus and nitrogen in the inflowing wastewater,
A biological reaction apparatus having an anaerobic tank, an anaerobic tank and an aerobic tank for biological treatment;
A high-speed filtration device that is provided in the previous stage of the biological reaction device, and that increases the removal rate of turbid components in the wastewater by forcibly filtering the wastewater through a filter medium layer;
A filter media backwash system for backwashing the filter media layer with the inflowing waste water;
A backwash drainage tank that retains backwash wastewater generated by backwashing the filter medium layer;
Agitation means for agitating the backwashing mud in the backwashing mud tank;
A liquid feed pump for charging the anaerobic tank with the supernatant liquid of the backwashed mud stirred and retained in the backwashed mud tank;
And Okudoro pump to inject sedimentation sludge of the backwash waste sludge which was stirred and residence in the backwash discharge sludge tank to the anoxic tank,
Means for turning on and off the liquid feeding pump based on the measurement result of the phosphorus concentration measuring means provided in the anaerobic tank;
It means for performing ON-OFF of the Okudoro pump based on the measurement result of the provided anoxic tank NO 3 _-N concentration measuring means,
A wastewater treatment apparatus characterized by comprising: