JP3825496B2

JP3825496B2 - Anaerobic fluidized bed wastewater treatment method and apparatus

Info

Publication number: JP3825496B2
Application number: JP5479396A
Authority: JP
Inventors: 巖水澤; 彰紀佐藤
Original assignee: Maezawa Kasei Kogyo KK
Current assignee: Maezawa Kasei Kogyo KK
Priority date: 1996-03-12
Filing date: 1996-03-12
Publication date: 2006-09-27
Anticipated expiration: 2016-03-12
Also published as: JPH09248591A

Description

【０００１】
【発明の属する技術分野】
本発明は嫌気性菌を保持した担体を循環させて生活排水および産業排水などの排水を嫌気的に処理する嫌気性流動床排水処理方法およびその装置に関する。
【０００２】
【従来の技術】
従来、生活排水および産業排水などの排水を嫌気的に処理する方法としては、汚泥中に含まれる嫌気性菌の嫌気処理により発生するガスを利用して自然循環して処理する排水（以下原水と称する。）との接触をよくする方法、機械的に撹拌を行い処理する原水との接触をよくする方法が採られてきた。近年、嫌気性菌の増殖が遅いことにより処理装置から処理排水とともに嫌気性菌が流出して菌数が減少することを防止するために、固定床に嫌気性菌を付着させる方法、さらには、原水との接触を改善するために、多孔質の担体に嫌気性菌を保持させたいわゆる固定化担体により装置内の菌数を多くして嫌気性処理の性能をさせる流動床が採用されるようになっている。
【０００３】
この流動床の性能向上には装置内の担体の比率（以下充填率と称する。）を高くすること、原水との接触をよくするために装置内の担体がなるべく均一に循環すること、嫌気処理がすすむにしたがって発生するメタン、窒素などのガスを菌体周辺から速やかに除去することが必要となる。
【０００４】
この担体の比率を高くし、担体が均一に循環し、さらに、ガスを菌体周辺から速やかに除去するためには、従来の撹拌翼による機械的撹拌によるか、処理装置から担体を分離した水を循環して水流を起こさせるか、或いは、発生したガスをブローワーなどを通して循環して曝気管から再び装置下部に吹き込み、担体を流動させる方法が採られていた。
【０００５】
【発明が解決しようとする課題】
前記機械的撹拌により担体を流動する方法では、発生したガスにより浮遊した担体を強制的に沈める必要から強い撹拌を必要とし、撹拌翼と担体とが衝突することにより、剪断力に弱い担体、例えば、セルロース、ポリウレタン樹脂などの多孔質担体では時間が経つにしたがって破壊され、担体としての機能が損なわれ、特に担体の充填率が高くなるとこの傾向が大きくなる問題がある。
【０００６】
一方、強度の高い担体、例えば、多孔質セラミックスを使用すれば、撹拌翼と担体との衝突に対する強度は確保されても、担体の比重が大きく、均一な流動を維持するには多大の動力を必要とする。このため、なるべく比重の軽い担体を剪断力が掛からずに循環させる方法として、排水処理槽内の水を担体と分離して排水処理槽の下部から挿入する方法、発生したガスを排水処理槽外に取り出し、ブローワーなどで再び排水処理槽下部に送り、曝気管を通じて排水処理槽内の一端から吹き込み担体を循環させる方法が知られているが、いずれも比重の軽い担体では発生したガスが担体に付着し、担体が水面上に浮き、担体の循環が円滑に行われず、処理性能を高めることができない。
【０００７】
このため、なるべく比重の軽い担体を剪断力が掛からずに循環させる方法としてエジェクターを使用し、排水処理槽上部より処理排水と担体とを吸引し、排水処理槽下部へ放出することにより循環させる方法が考えられるが、この場合、エジェクター導管内の管径がエジェクター部で狭くなることにより担体がこの部分詰まり、処理排水のみが循環する問題があり、担体の詰まりを防止するためには、担体の大きさをエジェクター導管の管径よりかなり小さくし、さらに、担体の充填率を低くする必要があり、担体を小さく充填率を低くすると処理性能の低下は免れない問題がある。
【０００８】
本発明は上記問題点に鑑みなされたもので、嫌気性菌を保持した担体を高充填率で排水処理槽内を循環させ、排水の嫌気処理を高効率にでき、耐剪断力が低く比重の小さい担体でも破壊することなく、嫌気処理が確実にでき、処理装置の小型化を図れる嫌気性流動床排水処理方法およびその装置を提供するものである。
【０００９】
【課題を解決するための手段】
本発明は、発明者により種々検討した結果、嫌気性菌を保持した比重の小さい担体を高充填率で排水処理槽内を循環させるには、上下面を排水処理槽内に開口した導管を排水処理槽内に配設し、この導管の下部に水を吹き付けることにより導管内に下降流を生じさせることが有効であることを知覚し、担体を導管内を上部から下部に向けて通過させ、この導管の下部から排水処理槽に放出された担体を導管の上部に導いて循環させるために、導管の下部に水を吹き付ける手段として、エジェクター方式を考え付いたが、エジェクター方式を採用して、ノズルの先端を導管内に突出させると、導管内に狭隘部が形成され、この部分に担体が引っ掛かり、さらに、この引っ掛かった担体に次の担体が引っ掛かり、順次担体が滞留して詰まり、導管内を閉塞することが判った。
【００１０】
また、導管の下部に水を吹き付ける手段として、排水処理槽の中心位置に配してこの導管の下部に直角にノズルを臨ませると、導管の下部から放出される担体と水は排水処理槽の内壁に直角に衝突し、排水処理槽の内壁に直角に衝突した担体と水は左右に分かれて内壁に沿って排水処理槽の反対側で衝突し、複雑な水流となり、一部の担体は排水処理槽の上部に浮上したままで、導管に再び吸引されず、担体と排水との接触が均等に行われず、効率のよい嫌気反応が行われない問題があることが判明した。
【００１１】
さらに、導管の下部に水を吹き付ける手段として、水を排水処理槽内に接線方向から放出することがエネルギー的にも効率がよいことから、水を接線方向から吹き付けるようにすると、排水処理槽の下部の構造が複雑となる問題があった。
【００１２】
そこで、排水処理槽内に上下方向の導管を配設し、さらに、この導管の下部に導管内面にノズルの先端を突出させずに配置し、このノズルから水を吹き出すことにより導管内に下降流を生じさせることが有効であることに着目して発明したものである。
【００１３】
また、排水処理槽内に配設した上下方向の導管を排水処理槽の中心より偏心した位置に配設することにより導管の下部から内壁に向って吹き付けられた担体と水が内壁に衝突することによって水流の強さに差が生じ、一方向の流れとなって旋回流となって徐々に浮上して排水との接触が確実に行われながら上昇することに着目してなされたものである。
【００１４】
請求項１記載の発明の嫌気性流動床排水処理方法は、導管を上下方向に向けて設置した排水処理槽内に嫌気性菌を保持した担体を高充填し、前記導管の下部に前記排水処理槽の上部から前記担体を分離した水を吹き込んで前記導管内に下降流を生じさせ、前記担体を前記導管内を上部から下部に通過させて、この導管の下部に導いた担体をこの導管の下部から放出させて処理槽内を旋回上昇させることにより、前記担体を前記導管の上部から下部に下降させるとともに前記排水処理槽内を下部から上部に向けて旋回上昇させて前記導管の上部に循環させるものである。
【００１５】
そして、予め嫌気性菌を保持した担体を高充填で分散させた排水処理槽内に排水の原水を連続的に流入させ、排水処理槽上部に循環した担体と排水とを導管内に吸引し、排水処理槽の下部より排水処理槽の内壁に沿って上昇させることを繰り返して嫌気処理を行い、排水処理槽内の排水の一部を排水処理槽外に処理水として排出する。この間に処理する排水と担体との接触が充分に行われ、嫌気性菌による嫌気反応が進行し、嫌気反応で発生したガスは導管内を下降中、または、排水処理槽内を旋回上昇中に担体表面から容易に離脱し、嫌気処理が効率よく行われる。
【００１６】
また、排水処理槽上部にある担体が排水処理槽下部に引き込む導管の内部に狭隘部がなく、担体が導管内に詰まって閉塞することがなく、装置の長時間連続運転が可能となる。
【００１７】
さらに、比重が小さく耐剪断力の低い担体でも破壊されることなく確実に循環し、効率よく嫌気処理ができる。
【００１８】
請求項２記載の発明の嫌気性流動床排水処理方法は、請求項１記載の嫌気性流動床排水処理方法において、導管の下部から放出された担体を排水処理槽内に旋回上昇させるものである。
【００１９】
そして、導管の下部から放出された担体を排水処理槽内に旋回上昇させることにより、処理する排水と担体との接触が充分に行われ、嫌気性菌による嫌気反応が効率よく行われる。
【００２０】
請求項３記載の発明の嫌気性流動床排水処理方法は、請求項１または２記載の嫌気性流動床排水処理方法において、担体は多孔質発泡体である。
【００２１】
そして、担体は多孔質体であるため、比重が小さく、ノズルから吹き出す水流を発生させるエネルギーを小さくできる。
【００２２】
請求項４記載の発明の嫌気性流動床排水処理装置は、排水処理槽と、この排水処理槽内に上下方向に向けて設置し上面および下部側面を前記排水処理槽内に開口した導管と、前記排水処理槽内に高充填され嫌気性菌を保持した担体と、前記導管の下部でこの導管の内面に突出しない位置に先端を臨ませ前記排水処理槽の上部から前記担体を分離した水を吹き込みこの導管内に下降流を生じさせるノズルとを備え、前記担体を前記導管の上部から下部に下降させるとともに前記排水処理槽内を下部から上部に向けて旋回上昇させて前記導管の上部に循環させるものである。
【００２３】
そして、予め嫌気性菌を保持した担体を高充填で分散させた排水処理槽内に排水の原水を連続的に流入させ、導管内に下降流を生じさせるノズルから吹き出す水により導管内に下降流を生じさせ、この下降流により排水処理槽に上昇流を生じさせ、排水処理槽上部に循環した担体と排水とを導管内に吸引し、排水処理槽の下部より排水処理槽の内壁に沿って旋回上昇させることを繰り返して嫌気処理を行い、排水処理槽内の排水の一部を排水処理槽外に処理水として排出する。この間に処理する排水と担体との接触が充分に行われ、嫌気性菌による嫌気反応が進行し、嫌気反応で発生したガスは導管内を下降中、または、排水処理槽内を旋回上昇中に担体表面から容易に離脱し、嫌気処理が効率よく行われる。
【００２４】
また、排水処理槽上部にある担体が排水処理槽下部に引き込む導管の内部にノズルが突出されていないため、導管内に狭隘部がなく、担体が導管内に詰まって閉塞することがなく、担体を比較的大きくでき、高充填が可能で効率のよい嫌気処理ができ、装置の長時間連続運転が可能となる。
【００２５】
さらに、比重が小さく耐剪断力の低い担体でも破壊されることなく確実に循環し、効率よく嫌気処理ができる。
【００２６】
請求項５記載の発明の嫌気性流動床排水処理装置は、請求項４記載の嫌気性流動床排水処理装置において、導管を排水処理槽の中心位置より偏心した位置に設置し、前記導管の下部から放出された担体を排水処理槽内に旋回上昇させるものである。
【００２７】
そして、導管の下部から放出された担体を排水処理槽内に旋回上昇させることにより、処理する排水と担体との接触が充分に行われ、嫌気性菌による嫌気反応が効率よく行われる。しかも、排水処理槽内に配設させる導管を排水処理槽の中心位置より偏心した位置に設置させるのみで、確実に旋回流が生じ、この旋回流を生じさせる動力を必要とせず、経済的に装置を運転でき、排水処理槽の構造も簡単になり、保守管理が容易となる。
【００２８】
請求項６記載の発明の嫌気性流動床排水処理装置は、請求項４または５記載の嫌気性流動床排水処理装置において、担体は多孔質体である。
【００２９】
そして、担体は多孔質体であるため、比重が小さく、ノズルから吹き出す水流を発生させるエネルギーを小さくできる。
【００３０】
【発明の実施の形態】
本発明の一実施の形態を図面に基づいて説明する。
【００３１】
１は略円筒状の排水処理槽で、中心位置より偏心した位置に上下方向に向けて円筒状の導管２が配設され、この導管２の上面前記排水処理槽１内に開口され、この導管２の下部は閉塞されるとともに下部側面に筒状の放出口３が開口されている。
【００３２】
この導管２の下部には前記筒状の放出口３に対向してこの導管２内にノズル４の先端がこの導管２の内面に突出することなくこの導管２と直角方向に接続され、このノズル４の先端開口部がこの導管２の内面と同一面に臨ませられている。このノズル４はポンプ５の吐出側が接続され、このポンプ５の吸水側は前記排水処理槽１の上部に水位位置６より下方に位置して側部に開口した吸い込み管７が接続されている。そして、前記排水処理槽１の上部には吸い込み管７の開口部に臨ませて担体８が吸い込み管７に流入することを阻止するフィルタ網９が張設されている。
【００３３】
また、前記排水処理槽１内の上部に水位位置６より上方に位置して先端を上向きに開口した原水導入管10が設けられ、この原水導入管10の下方に位置して前記排水処理槽１の側部に処理水流出管11が開口接続されている。そして、前記排水処理槽１の上部には処理水流出管11の開口部に臨ませて担体８が処理水流出管11に流出することを阻止するフィルタ網９が張設されている。
【００３４】
また、前記排水処理槽１の上面開口部にはこの開口部を密封する処理槽蓋12が開閉自在に設けられ、この処理槽蓋12には嫌気反応により生成された生成ガスを排水処理槽１の外方に排気するガス抜き取り管13が設けられている。
【００３５】
さらに、前記処理槽蓋12には水素供給体としてのメタノールなどの有機炭素源を前記排水処理槽１内に供給する配管14が設けられている。
【００３６】
また、前記担体８は嫌気性菌を保持するもので、天然セルロース、ポリウレタン樹脂などの高分子発泡体のような多孔質体にて形成されている。
【００３７】
次にこの実施の形態の作用を説明する。
【００３８】
排水処理槽１内に排水に予め嫌気性菌を保持した担体８を高充填で分散させ、この状態で排水処理槽１内に原水導入管10から原水を連続的に流入させると、原水は排水処理槽１内の排水と混合される。そして、ポンプ５の駆動により排水処理槽１の上部の水位位置６より下方に位置して開口した吸い込み管７から排水処理槽１内の排水がノズル４から導管２の下部に直角方向から吹き付けられ、このとき、フィルタ網９により排水処理槽１の担体８が吸い込み管７に流入することが阻止されている。
【００３９】
このノズル４から吹き出す水により導管２内に下降流が生じ、この導管２内の下降流により排水処理槽１には上昇流が生じ、担体８と排水は排水処理槽１の下部より排水処理槽１の内壁に沿って上昇され、排水処理槽１の上部に循環した担体８と排水とが導管２内に吸引され、この循環を繰り返してこの間に処理する排水と担体８との接触が充分に行われて嫌気性菌による嫌気反応が進行して嫌気処理が行われる。
【００４０】
また、排水処理槽１の上部にある担体８が排水処理槽１の下部に引き込む導管２の内部にノズル４が突出されていないため、導管２内に狭隘部がなく、担体８が導管２内に詰まって閉塞することがなく、担体８を大きくしても、高充填が可能で効率のよい長時間連続運転の嫌気処理ができる。
【００４１】
さらに、排水処理槽１内に配設させる導管２は排水処理槽１の中心位置より偏心した位置に設置されているため、導管２の下部放出口３から放出された担体８と水は排水処理槽１の内壁に衝突することによって水流の強さに差が生じることにより一方向の流れとなって旋回流となり、排水処理槽１の内壁に沿って確実に旋回上昇され、担体８は徐々に浮上して排水との接触が確実に行われながら処理する排水と担体８との接触が充分に行われ、嫌気性菌による嫌気反応が効率よく行われる。
【００４２】
また、担体８には機械的撹拌力が作用しないので、天然セルロース、ポリウレタン樹脂発泡体のような多孔質体で耐剪断力の低い担体でも破壊されることなく確実に循環し、効率よく嫌気処理ができる。さらに、担体８は多孔質体で比重が小さく、ノズルから吹き出す水流を発生させるエネルギーを小さくできる。
【００４３】
そして、排水処理槽１内の排水の一部は排水処理槽１の上部に開口部を臨ませた処理水流出管11から排水処理槽１外に処理水として排出する。このとき、担体８は処理水流出管11に流出することをフィルタ網９にて阻止される。
【００４４】
また、嫌気性菌による嫌気反応が進行し、嫌気反応で発生したガスは導管２内を下降中、または、排水処理槽１内を上昇中に担体８の表面から容易に離脱し、排水処理槽１の処理槽蓋12に設けたられたガス抜き取り管13から排水処理槽１の外方に排気される。
【００４５】
さらに、必要に応じて前記処理槽蓋12に設けた配管14からメタノールが供給される。
【００４６】
なお、導管２の放出口３から放出される担体８と水とにて生じる循環水の流速が遅ければ、導管２の上部から吸い込まれることがなく、また、流速が速くなると、循環する担体８の導管２の上面からの吸い込みが良好となるが、動力的には不経済となるので、ノズル４の先端部で、流速は４m ／sec ないし7.5m／sec が好適である。
【００４７】
【実施例】
次に本発明の嫌気性流動床排水処理装置の一実施例を説明する。
【００４８】
排水処理槽１の実容積は2.5 ｌの内部に内径30mmの導管２を設置し、５mm×５mm×５mmの大きさの予め脱窒菌を付着させたセルロース系担体８を充填率20％とし、原水流入量を0.83ｌ／Hr、原水滞留時間を３時間、循環水流速を４m/sec 、有機炭素源としてメタノールを用い、原水流入量に対するメタノールの注入量を135mg ／ｌとする。
【００４９】
この実施例による試験結果は、原水中のNO₃性窒素は67.6mg／ｌで、処理水中のNO₃性窒素は0.3mg ／ｌとなり、NO₃性窒素の除去率は99.6％となった。
【００５０】
また、この装置で、セルロース系担体８を充填率40％とし、原水流入量を2.5 ｌ／Hr、原水滞留時間を１時間、循環水流速を７m/sec 、有機炭素源としてメタノールを用い、原水流入量に対するメタノールの注入量を180mg ／ｌとすると、その試験結果は、原水中のNO₃性窒素は102.6mg ／ｌで、処理水中のNO₃性窒素は2.4mg ／ｌとなり、NO₃性窒素の除去率は97.7％となった。
【００５１】
次に本発明の嫌気性流動床排水処理装置の他の実施例を説明する。
【００５２】
排水処理槽１の実容積は1000ｌの内部に内径150mm の導管２を設置し、10mm×10mm×10mmの大きさの予め脱窒菌を付着させたウレタン樹脂系担体８を充填率20％とし、原水流入量を 330ｌ／Hr、原水滞留時間を３時間、循環水流速を６m/sec 、有機炭素源としてメタノールを用い、原水流入量に対するメタノールの注入量を140mg ／ｌとして４か月試験した。
【００５３】
この実施例による試験結果は、処理水中のNO₃性窒素平均値は0.9mg ／ｌとなり、NO₃性窒素の平均除去率は98.7％となった。この間、導管２の閉塞はなく、担体８の崩れ、破壊はなかった。
【００５４】
なお、この担体８を均一になるように撹拌機で機械撹拌すると、３か月程度で担体８は崩れはじめ実用に供し得なくなった。
【００５５】
【発明の効果】
請求項１記載の発明によれば、処理する排水と担体との接触が充分に行われ、排水の嫌気処理を高効率にでき、耐剪断力が低く比重の小さい担体でも破壊することなく、嫌気処理が確実にでき、処理装置の小型化を図れる。
【００５６】
請求項２記載の発明によれば、担体は排水処理槽内を旋回上昇させることにより、処理する排水と担体との接触が充分に行われ、嫌気性菌による嫌気反応が効率よく行われる。
【００５７】
請求項３記載の発明によれば、担体は多孔質体であるため、比重が小さく、ノズルから吹き出す水流を発生させるエネルギーを小さくできる。
【００５８】
請求項４記載の発明によれば、処理する排水と担体との接触が充分に行われ、嫌気性菌による嫌気反応が活発となり、嫌気処理が効率よく行われる。
【００５９】
また、導管内に狭隘部がなく、担体が導管内に詰まって閉塞することがなく、担体を比較的大きくでき、高充填が可能で効率のよい嫌気処理ができ、装置の長時間連続運転が可能となる。
【００６０】
さらに、比重が小さく耐剪断力の低い担体でも破壊されることなく確実に循環し、効率よく嫌気処理ができる。
【００６１】
請求項５記載の発明によれば、担体を排水処理槽内に旋回上昇でき、処理する排水と担体との接触が充分に行われ、嫌気性菌による嫌気反応が効率よく行われる。しかも、確実に旋回流が生じ、この旋回流を生じさせる動力を必要とせず、経済的に装置を運転でき、排水処理槽の構造も簡単になり、保守管理が容易となる。
【００６２】
請求項６記載の発明によれば、担体は多孔質体であるため、比重が小さく、ノズルから吹き出す水流を発生させるエネルギーを小さくできる。
【図面の簡単な説明】
【図１】本発明の一実施の形態を示す嫌気性流動床排水処理装置の縦断説明正面図である。
【図２】同上嫌気性流動床排水処理装置の横断説明平面図である。
【図３】同上嫌気性流動床排水処理装置の導管に設けたノズル部の縦断拡大説明正面図である。
【符号の説明】
１排水処理槽
２導管
４ノズル
８嫌気性菌を保持した担体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an anaerobic fluidized bed wastewater treatment method and apparatus for anaerobically treating wastewater such as domestic wastewater and industrial wastewater by circulating a carrier holding anaerobic bacteria.
[0002]
[Prior art]
Conventionally, as a method for anaerobically treating wastewater such as domestic wastewater and industrial wastewater, wastewater (hereinafter referred to as raw water) treated by natural circulation using gas generated by anaerobic treatment of anaerobic bacteria contained in sludge. And a method for improving the contact with the raw water to be treated by mechanical stirring. In recent years, in order to prevent anaerobic bacteria from flowing out of the treatment apparatus due to slow growth of anaerobic bacteria and reducing the number of bacteria, the method of attaching anaerobic bacteria to the fixed bed, In order to improve contact with raw water, a fluidized bed that increases the number of bacteria in the apparatus by using a so-called immobilized carrier in which anaerobic bacteria are held in a porous carrier to improve the performance of anaerobic treatment will be adopted. It has become.
[0003]
In order to improve the performance of the fluidized bed, the ratio of the carrier in the apparatus (hereinafter referred to as the filling rate) is increased, the carrier in the apparatus is circulated as uniformly as possible in order to improve contact with the raw water, and anaerobic treatment. It is necessary to quickly remove gases such as methane and nitrogen that are generated as the process progresses from the periphery of the cells.
[0004]
In order to increase the ratio of the carrier, circulate the carrier uniformly, and to quickly remove the gas from the periphery of the cells, water can be removed by mechanical stirring with a conventional stirring blade or by separating the carrier from the treatment device. In this case, a water flow is generated by circulating the gas, or the generated gas is circulated through a blower or the like and blown again from the aeration pipe into the lower part of the apparatus to flow the carrier.
[0005]
[Problems to be solved by the invention]
In the method of flowing the carrier by the mechanical stirring, strong stirring is required because it is necessary to forcibly sink the carrier suspended by the generated gas, and the carrier weak against the shearing force due to collision between the stirring blade and the carrier, for example, In the case of porous carriers such as cellulose and polyurethane resin, the carrier is destroyed over time, and the function as the carrier is impaired. In particular, when the filling rate of the carrier is increased, this tendency is increased.
[0006]
On the other hand, if a high-strength carrier, for example, porous ceramics is used, even if the strength against the collision between the stirring blade and the carrier is ensured, the specific gravity of the carrier is large and a large amount of power is required to maintain a uniform flow. I need. For this reason, as a method for circulating a carrier having a light specific gravity as much as possible without applying a shearing force, water in the waste water treatment tank is separated from the carrier and inserted from the lower part of the waste water treatment tank, and the generated gas is discharged from the waste water treatment tank. It is known that the carrier is circulated from one end of the wastewater treatment tank through the aeration pipe and circulated through the aeration pipe to the lower part of the wastewater treatment tank. The carrier adheres and floats on the water surface, and the carrier is not circulated smoothly, so that the processing performance cannot be improved.
[0007]
For this reason, using an ejector as a method of circulating a carrier with a light specific gravity as much as possible without applying a shearing force, a method of circulating the waste water and carrier by sucking them from the upper part of the waste water treatment tank and discharging them to the lower part of the waste water treatment tank However, in this case, there is a problem that the carrier clogs due to the narrowed diameter of the tube in the ejector conduit, and only the treated wastewater circulates. In order to prevent clogging of the carrier, It is necessary to make the size considerably smaller than the tube diameter of the ejector conduit, and to lower the filling rate of the carrier.
[0008]
The present invention has been made in view of the above-mentioned problems, and a carrier holding anaerobic bacteria is circulated in a wastewater treatment tank at a high filling rate, so that anaerobic treatment of wastewater can be made highly efficient, with low shear resistance and low specific gravity. An anaerobic fluidized bed wastewater treatment method and apparatus capable of reliably performing anaerobic treatment without destroying even a small carrier and reducing the size of the treatment apparatus.
[0009]
[Means for Solving the Problems]
As a result of various studies by the inventor of the present invention, in order to circulate a carrier having a low specific gravity holding anaerobic bacteria at a high filling rate in a wastewater treatment tank, a conduit having an upper and lower surface opened in the wastewater treatment tank is drained. Perceived that it is effective to create a downward flow in the conduit by spraying water on the lower portion of the conduit disposed in the treatment tank, and passing the carrier through the conduit from the top to the bottom, In order to circulate the carrier discharged from the lower part of the conduit into the wastewater treatment tank to the upper part of the conduit and circulate it, the ejector method was devised as a means of spraying water to the lower part of the conduit. When the tip of the tube is protruded into the conduit, a narrow portion is formed in the conduit, and the carrier is caught in this portion. Further, the next carrier is caught in the caught carrier, and the carrier is successively retained and clogged. It was found that closing the.
[0010]
Also, as a means of spraying water to the lower part of the conduit, if the nozzle is placed at a right angle to the lower part of the drainage treatment tank, the carrier and water released from the lower part of the conduit will be removed from the wastewater treatment tank. The carrier and water that collided perpendicularly to the inner wall and collided perpendicularly to the inner wall of the wastewater treatment tank split into left and right, collided along the inner wall on the opposite side of the wastewater treatment tank, creating a complex water flow, and some of the carrier is drained It has been found that there is a problem in that it remains floating at the top of the treatment tank and is not sucked again into the conduit, the contact between the carrier and the waste water is not evenly performed, and an efficient anaerobic reaction is not performed.
[0011]
Furthermore, as a means of spraying water to the lower part of the conduit, it is efficient in terms of energy to discharge water from the tangential direction into the wastewater treatment tank. There was a problem that the structure of the lower part was complicated.
[0012]
Therefore, a vertical conduit is arranged in the waste water treatment tank, and further, a nozzle is arranged on the inner surface of the conduit without projecting the tip of the nozzle at the bottom of the conduit, and water is blown down into the conduit by blowing water from the nozzle. It is invented paying attention to the fact that it is effective to generate.
[0013]
Moreover, the carrier and water sprayed from the lower part of the conduit toward the inner wall collide with the inner wall by arranging the vertical conduit arranged in the waste water treatment tank at a position eccentric from the center of the wastewater treatment tank. The difference in the strength of the water flow is caused by the above, and it has been made by paying attention to the fact that it gradually rises as a swirling flow as a one-way flow and rises while reliably making contact with the drainage.
[0014]
An anaerobic fluidized bed wastewater treatment method according to a first aspect of the present invention is a wastewater treatment tank in which a conduit is installed in a vertical direction with a high amount of a carrier holding anaerobic bacteria, and the wastewater treatment at a lower portion of the conduit. The water separated from the carrier from the upper part of the tank is blown to cause a downward flow in the conduit, the carrier is passed through the conduit from the upper part to the lower part, and the carrier guided to the lower part of the conduit is passed through the conduit. The carrier is lowered from the upper part of the conduit to the lower part by discharging from the lower part and swirling up in the treatment tank, and the carrier is swirled and raised from the lower part to the upper part to circulate in the upper part of the conduit. It is something to be made.
[0015]
And, the raw water of the waste water is continuously flowed into the waste water treatment tank in which the carrier holding the anaerobic bacteria is dispersed with high filling, and the carrier and waste water circulated in the upper part of the waste water treatment tank are sucked into the conduit, Anaerobic treatment is performed by repeatedly raising the wastewater treatment tank along the inner wall of the wastewater treatment tank, and a part of the wastewater in the wastewater treatment tank is discharged out of the wastewater treatment tank as treated water. During this time, the wastewater to be treated and the carrier are sufficiently in contact, the anaerobic reaction by anaerobic bacteria proceeds, and the gas generated by the anaerobic reaction is descending in the conduit or swirling up in the wastewater treatment tank It is easily detached from the surface of the carrier, and anaerobic treatment is performed efficiently.
[0016]
Further, there is no narrow portion in the inside of the conduit where the carrier at the upper part of the waste water treatment tank is drawn into the lower part of the waste water treatment tank, and the carrier is not clogged and clogged in the conduit, and the apparatus can be operated continuously for a long time.
[0017]
Furthermore, even a carrier having a small specific gravity and a low shear strength can be reliably circulated without being broken, and an anaerobic treatment can be performed efficiently.
[0018]
An anaerobic fluidized bed wastewater treatment method according to a second aspect of the present invention is the anaerobic fluidized bed wastewater treatment method according to the first aspect, wherein the carrier released from the lower part of the conduit is swirled and raised into the wastewater treatment tank. .
[0019]
And by making the support | carrier discharge | released from the lower part of the conduit | powder swirl up in a wastewater treatment tank, the waste_water | drain to process and a support | carrier are fully contacted, and the anaerobic reaction by anaerobic bacteria is performed efficiently.
[0020]
An anaerobic fluidized bed wastewater treatment method according to a third aspect of the present invention is the anaerobic fluidized bed wastewater treatment method according to the first or second aspect, wherein the carrier is a porous foam.
[0021]
And since a support | carrier is a porous body, specific gravity is small and the energy which generate | occur | produces the water flow which blows off from a nozzle can be made small.
[0022]
The anaerobic fluidized bed wastewater treatment device of the invention according to claim 4 is a wastewater treatment tank, a conduit that is installed in the wastewater treatment tank in the vertical direction, and has an upper surface and a lower side surface opened in the wastewater treatment tank, A carrier that is highly filled in the wastewater treatment tank and holds anaerobic bacteria, and water that separates the carrier from the upper part of the wastewater treatment tank by facing the tip at a position that does not protrude from the inner surface of the conduit at the bottom of the conduit. And a nozzle for generating a downward flow in the conduit. The carrier is lowered from the upper portion of the conduit to the lower portion, and circulated in the waste water treatment tank from the lower portion to the upper portion to circulate in the upper portion of the conduit. It is something to be made.
[0023]
Then, the raw water of the waste water is continuously flowed into the waste water treatment tank in which the carrier holding the anaerobic bacteria is dispersed in a highly filled state, and the water is blown down into the conduit by the water blown from the nozzle that generates the downward flow in the conduit. This downward flow causes an upward flow in the wastewater treatment tank, and the carrier and wastewater circulated in the upper part of the wastewater treatment tank are sucked into the conduit, and along the inner wall of the wastewater treatment tank from the lower part of the wastewater treatment tank. Anaerobic treatment is performed by repeatedly turning and raising, and part of the wastewater in the wastewater treatment tank is discharged out of the wastewater treatment tank as treated water. During this time, the wastewater to be treated and the carrier are sufficiently in contact, the anaerobic reaction by anaerobic bacteria proceeds, and the gas generated by the anaerobic reaction is descending in the conduit or swirling up in the wastewater treatment tank It is easily detached from the surface of the carrier, and anaerobic treatment is performed efficiently.
[0024]
Also, since the nozzle in the upper part of the waste water treatment tank is drawn into the lower part of the waste water treatment tank, the nozzle does not protrude, so there is no narrow part in the conduit and the carrier is not clogged and clogged. Can be made relatively large, high filling is possible, efficient anaerobic treatment can be performed, and the apparatus can be operated continuously for a long time.
[0025]
Furthermore, even a carrier having a small specific gravity and a low shear strength can be reliably circulated without being broken, and an anaerobic treatment can be performed efficiently.
[0026]
An anaerobic fluidized bed wastewater treatment apparatus according to a fifth aspect of the present invention is the anaerobic fluidized bed wastewater treatment apparatus according to the fourth aspect, wherein the conduit is installed at a position eccentric from the center position of the wastewater treatment tank, The carrier released from the water is swung up into the waste water treatment tank.
[0027]
And by making the support | carrier discharge | released from the lower part of the conduit | powder swirl up in a wastewater treatment tank, the waste_water | drain to process and a support | carrier are fully contacted, and the anaerobic reaction by anaerobic bacteria is performed efficiently. Moreover, it is economically possible to generate a swirling flow reliably without requiring the power to generate the swirling flow by simply installing the conduit disposed in the waste water treatment tank at a position eccentric from the center position of the waste water treatment tank. The apparatus can be operated, the structure of the wastewater treatment tank is simplified, and maintenance management is facilitated.
[0028]
An anaerobic fluidized bed wastewater treatment apparatus according to a sixth aspect of the present invention is the anaerobic fluidized bed wastewater treatment apparatus according to the fourth or fifth aspect, wherein the carrier is a porous body.
[0029]
And since a support | carrier is a porous body, specific gravity is small and the energy which generate | occur | produces the water flow which blows off from a nozzle can be made small.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
[0031]
Reference numeral 1 denotes a substantially cylindrical waste water treatment tank. A cylindrical conduit 2 is arranged in a vertical direction at a position eccentric from the center position, and an upper surface of the conduit 2 is opened in the waste water treatment tank 1. The lower part of 2 is closed and a cylindrical discharge port 3 is opened on the lower side surface.
[0032]
At the lower part of the conduit 2, the tip of the nozzle 4 is connected to the conduit 2 at a right angle without protruding from the inner surface of the conduit 2, facing the cylindrical discharge port 3. 4 is opened to the same plane as the inner surface of the conduit 2. The nozzle 4 is connected to the discharge side of the pump 5, and the water suction side of the pump 5 is connected to the upper part of the waste water treatment tank 1 and a suction pipe 7 which is located below the water level position 6 and is open to the side. A filter net 9 is stretched over the drainage treatment tank 1 so as to face the opening of the suction pipe 7 and prevent the carrier 8 from flowing into the suction pipe 7.
[0033]
In addition, a raw water introduction pipe 10 is provided above the water level tank 6 with the tip opened upward at the upper part in the waste water treatment tank 1, and located below the raw water introduction pipe 10 and located in the waste water treatment tank 1. A treated water outflow pipe 11 is open-connected to the side portion of this. A filter net 9 is stretched over the waste water treatment tank 1 so as to face the opening of the treated water outflow pipe 11 and prevent the carrier 8 from flowing out into the treated water outflow pipe 11.
[0034]
Further, a treatment tank lid 12 that seals the opening is provided in the upper surface opening of the waste water treatment tank 1 so as to be openable and closable. The generated gas generated by the anaerobic reaction is supplied to the treatment tank lid 12 from the waste water treatment tank 1. A gas vent pipe 13 for exhausting outside is provided.
[0035]
Further, the treatment tank lid 12 is provided with a pipe 14 for supplying an organic carbon source such as methanol as a hydrogen supply body into the waste water treatment tank 1.
[0036]
The carrier 8 holds anaerobic bacteria and is formed of a porous material such as a polymer foam such as natural cellulose or polyurethane resin.
[0037]
Next, the operation of this embodiment will be described.
[0038]
If the carrier 8 holding the anaerobic bacteria in the wastewater treatment tank 1 in advance is dispersed with high filling and the raw water is continuously flowed into the wastewater treatment tank 1 from the raw water introduction pipe 10 in this state, the raw water is drained. It is mixed with the waste water in the treatment tank 1. Then, the waste water in the waste water treatment tank 1 is blown from the nozzle 4 to the lower part of the conduit 2 from the right angle from the suction pipe 7 which is opened below the water level position 6 in the upper part of the waste water treatment tank 1 by driving the pump 5. At this time, the filter 8 prevents the carrier 8 of the wastewater treatment tank 1 from flowing into the suction pipe 7.
[0039]
The water blown out from the nozzle 4 causes a downward flow in the conduit 2, and the downward flow in the conduit 2 causes an upward flow in the wastewater treatment tank 1. The carrier 8 and the wastewater are discharged from the lower portion of the wastewater treatment tank 1. The carrier 8 and the drainage which are raised along the inner wall of 1 and circulated in the upper part of the wastewater treatment tank 1 are sucked into the conduit 2, and the circulation and the wastewater to be treated in the meantime are sufficiently contacted with each other. The anaerobic reaction by anaerobic bacteria proceeds and anaerobic treatment is performed.
[0040]
Further, since the nozzle 4 is not projected inside the conduit 2 where the carrier 8 at the upper part of the wastewater treatment tank 1 is drawn into the lower part of the wastewater treatment tank 1, there is no narrow portion in the conduit 2, and the carrier 8 is in the conduit 2. Even if the carrier 8 is enlarged, it is possible to perform anaerobic treatment for a long continuous operation with high efficiency even if the carrier 8 is enlarged.
[0041]
Furthermore, since the conduit 2 disposed in the waste water treatment tank 1 is installed at a position eccentric from the center position of the waste water treatment tank 1, the carrier 8 and water discharged from the lower discharge port 3 of the conduit 2 are treated as waste water. By colliding with the inner wall of the tank 1, a difference in the strength of the water flow is generated, so that the unidirectional flow becomes a swirling flow and is reliably swirled and raised along the inner wall of the wastewater treatment tank 1. The waste water to be treated and the carrier 8 are sufficiently brought into contact with the waste water while ascending and reliably coming into contact with the waste water, and the anaerobic reaction by the anaerobic bacteria is efficiently performed.
[0042]
In addition, since the mechanical stirring force does not act on the carrier 8, the porous material such as natural cellulose and polyurethane resin foam and the carrier having low shear resistance can be reliably circulated without being destroyed and efficiently anaerobically treated. Can do. Furthermore, the carrier 8 is a porous body and has a low specific gravity, so that energy for generating a water flow blown from the nozzle can be reduced.
[0043]
A part of the waste water in the waste water treatment tank 1 is discharged out of the waste water treatment tank 1 from the treated water outflow pipe 11 with the opening facing the upper part of the waste water treatment tank 1 as treated water. At this time, the filter 8 prevents the carrier 8 from flowing out into the treated water outflow pipe 11.
[0044]
Further, anaerobic reaction caused by anaerobic bacteria proceeds, and the gas generated by the anaerobic reaction is easily detached from the surface of the carrier 8 while descending in the conduit 2 or rising in the wastewater treatment tank 1, and the wastewater treatment tank 1 is exhausted to the outside of the waste water treatment tank 1 from a gas vent pipe 13 provided in one treatment tank lid 12.
[0045]
Furthermore, methanol is supplied from a pipe 14 provided in the processing tank lid 12 as necessary.
[0046]
If the flow rate of the circulating water generated by the carrier 8 and water discharged from the discharge port 3 of the conduit 2 is slow, it is not sucked from the upper part of the conduit 2, and if the flow rate becomes fast, the circulating carrier 8 is circulated. Although the suction from the upper surface of the conduit 2 is good, it is uneconomical in terms of power, so that the flow velocity at the tip of the nozzle 4 is preferably 4 m / sec to 7.5 m / sec.
[0047]
【Example】
Next, an embodiment of the anaerobic fluidized bed wastewater treatment apparatus of the present invention will be described.
[0048]
The actual volume of the wastewater treatment tank 1 is 2.5 liters, a conduit 2 having an inner diameter of 30 mm is installed, and a cellulosic carrier 8 to which denitrifying bacteria of 5 mm × 5 mm × 5 mm is attached in advance is set to a filling rate of 20%, and raw water The inflow rate is 0.83 l / Hr, the raw water residence time is 3 hours, the circulating water flow rate is 4 m / sec, methanol is used as the organic carbon source, and the amount of methanol injected relative to the raw water inflow rate is 135 mg / l.
[0049]
Test results of this example, NO ₃ nitrogen in raw water is 67.6 mg / l, NO ₃ nitrogen in the treated water 0.3 mg / l, and the removal rate of NO ₃ nitrogen was 99.6%.
[0050]
In this apparatus, the cellulose carrier 8 is filled at 40%, the raw water inflow is 2.5 l / Hr, the raw water residence time is 1 hour, the circulating water flow rate is 7 m / sec, and methanol is used as the organic carbon source. When the injection amount of methanol to inflow and 180 mg / l, the test result, NO ₃ nitrogen in raw water is 102.6mg / l, NO ₃ nitrogen in the treated water 2.4 mg / l next, NO ₃ properties The nitrogen removal rate was 97.7%.
[0051]
Next, another embodiment of the anaerobic fluidized bed wastewater treatment apparatus of the present invention will be described.
[0052]
The actual volume of the wastewater treatment tank 1 is 1000 liters, a conduit 2 with an inner diameter of 150 mm is installed, and a urethane resin carrier 8 with a denitrifying bacteria of 10 mm x 10 mm x 10 mm attached in advance with a filling rate of 20%, raw water The test was conducted for 4 months with an inflow rate of 330 l / Hr, a raw water residence time of 3 hours, a circulating water flow rate of 6 m / sec, methanol as the organic carbon source, and an injection amount of methanol with respect to the raw water inflow rate of 140 mg / l.
[0053]
As a result of the test according to this example, the average value of NO ₃ nitrogen in the treated water was 0.9 mg / l, and the average removal rate of NO ₃ nitrogen was 98.7%. During this time, there was no blockage of the conduit 2, and there was no collapse or destruction of the carrier 8.
[0054]
When the carrier 8 was mechanically stirred with a stirrer so as to be uniform, the carrier 8 started to collapse in about three months and became unusable.
[0055]
【The invention's effect】
According to the first aspect of the present invention, the waste water to be treated and the carrier are sufficiently brought into contact with each other, the anaerobic treatment of the waste water can be made highly efficient, and even the carrier having a low shear resistance and a low specific gravity can be anaerobically destroyed. Processing can be ensured and the processing apparatus can be downsized.
[0056]
According to the invention described in claim 2, the carrier is swirled and raised in the waste water treatment tank, so that the waste water to be treated and the carrier are sufficiently brought into contact with each other, and the anaerobic reaction by the anaerobic bacteria is efficiently performed.
[0057]
According to invention of Claim 3, since a support | carrier is a porous body, specific gravity is small and the energy which generate | occur | produces the water flow which blows off from a nozzle can be made small.
[0058]
According to invention of Claim 4, the waste_water | drain to process and a support | carrier are fully performed, the anaerobic reaction by an anaerobic microbe becomes active, and anaerobic processing is performed efficiently.
[0059]
In addition, there is no narrow part in the conduit, the carrier is not clogged and clogged in the conduit, the carrier can be made relatively large, high filling is possible, efficient anaerobic treatment is possible, and the apparatus can be operated continuously for a long time. It becomes possible.
[0060]
Furthermore, even a carrier having a small specific gravity and a low shear strength can be reliably circulated without being broken, and an anaerobic treatment can be performed efficiently.
[0061]
According to invention of Claim 5, a support | carrier can be swirled and raised in a waste water treatment tank, the waste_water | drain to process and a support | carrier are fully performed, and the anaerobic reaction by anaerobic bacteria is performed efficiently. In addition, a swirl flow is surely generated, no power is required to generate this swirl flow, the apparatus can be operated economically, the structure of the waste water treatment tank is simplified, and maintenance management is facilitated.
[0062]
According to invention of Claim 6, since a support | carrier is a porous body, specific gravity is small and the energy which generate | occur | produces the water flow which blows off from a nozzle can be made small.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional front view of an anaerobic fluidized bed wastewater treatment apparatus showing an embodiment of the present invention.
FIG. 2 is a cross-sectional explanatory plan view of the anaerobic fluidized bed wastewater treatment apparatus.
FIG. 3 is a longitudinally enlarged explanatory front view of a nozzle portion provided in a conduit of the anaerobic fluidized bed wastewater treatment apparatus.
[Explanation of symbols]
1 Wastewater treatment tank 2 Conduit 4 Nozzle 8 Carrier holding anaerobic bacteria

Claims

In the wastewater treatment tank in which the conduit is installed in the vertical direction, the carrier holding the anaerobic bacteria is highly filled, and water separated from the carrier from the upper part of the wastewater treatment tank is blown into the lower part of the conduit to blow the inside of the conduit By causing the carrier to pass through the conduit from the top to the bottom and discharging the carrier guided to the bottom of the conduit from the bottom of the conduit to swirl up the treatment tank. An anaerobic fluidized bed wastewater treatment method, wherein the carrier is lowered from the upper part to the lower part of the conduit, and the inside of the wastewater treatment tank is swung upward from the lower part to the upper part and circulated to the upper part of the conduit.

The anaerobic fluidized bed wastewater treatment method according to claim 1, wherein the carrier discharged from the lower part of the conduit is swirled and raised into the wastewater treatment tank.

The anaerobic fluidized bed wastewater treatment method according to claim 1 or 2, wherein the carrier is a porous body.

A wastewater treatment tank, a conduit installed in the wastewater treatment tank in the vertical direction and having an upper surface and a lower side surface opened into the wastewater treatment tank, and a carrier that holds the anaerobic bacteria highly filled in the wastewater treatment tank And a nozzle that blows water from which the carrier is separated from the upper part of the waste water treatment tank and causes a downward flow in the conduit by facing the tip at a position that does not protrude from the inner surface of the conduit at the lower part of the conduit, An anaerobic fluidized bed wastewater treatment apparatus characterized in that the carrier is lowered from the upper part of the conduit to the lower part, and the inside of the wastewater treatment tank is swung upward from the lower part to the upper part and circulated in the upper part of the conduit.

The anaerobic fluidized bed wastewater treatment according to claim 4, wherein the conduit is installed at a position eccentric from the central position of the wastewater treatment tank, and the carrier released from the lower part of the conduit is swirled and raised into the wastewater treatment tank. apparatus.

The anaerobic fluidized bed wastewater treatment apparatus according to claim 4 or 5, wherein the carrier is a porous body.