JP3841394B2

JP3841394B2 - High concentration organic wastewater treatment method and equipment

Info

Publication number: JP3841394B2
Application number: JP2001070470A
Authority: JP
Inventors: 光宏徳野; 厚史小林; 雄一村中; 和雄藤田; 彰川上; 裕一府中
Original assignee: Ebara Corp
Current assignee: Ebara Corp
Priority date: 2001-03-13
Filing date: 2001-03-13
Publication date: 2006-11-01
Anticipated expiration: 2021-03-13
Also published as: JP2002263672A

Description

【０００１】
【発明の属する技術分野】
本発明は、高濃度有機性排水の処理方法に係り、流動床式生物処理法と活性汚泥法を組み合わせることにより、処理スペースの縮小と省エネルギー化を伴う、高能率で処理し得る処理方法に関するものである。
【０００２】
【従来の技術】
有機性排水を生物処理する方法としては、活性汚泥処理法が広く用いられており、特に高濃度有機性排水の処理方法としては、第１段目を高負荷に設定して処理する２段活性汚泥処理法（吸着−活性汚泥法：ＡＢ法）が広く知られている。この２段活性汚泥処理法においては、前段と後段との負荷が異なるため、各段それぞれ別々の生物相の働きにより処理が行われている。
さらに、２段活性汚泥処理法について詳述すると、有機性排水を、第１段目で主に細菌類を主体とした微生物処理により、排水中の有機物を酸化分解すると共に、非凝集性の細菌に変換させた後、第２段目で当該非凝集性細菌を、原生動物を主体とした微生物処理により捕食除去させることによって、生物処理効率を向上させる処理方法である。これにより、第１段目で高負荷運転が可能になり、活性汚泥処理法による処理効率が向上すると同時に、余剰汚泥の生成量を少なくすることができる。
【０００３】
また、近年では２段活性汚泥処理の第１段目を流動床式生物処理法とする処理が注目されている。具体的には、廃水をまず微生物担体を懸濁させた系で生物学的に処理し、第一沈殿槽で汚泥を沈殿分離し、そこで得られた一次処理水を第２工程の活性汚泥を入れた曝気槽に送って生物学的に処理し、曝気槽からの流出水を第二沈殿槽で汚泥を沈殿分離することにより処理水を得る方法が知られている。
【０００４】
さらに、この方法では第二沈殿槽で沈殿分離した汚泥を微生物担体を懸濁させた系からの流出水に添加することにより、第一沈殿槽での汚泥の沈殿分離を促進させる作用を行わせるようにしている。
この方法は、高能率ではあるが、処理槽及び沈殿槽の組合せが各２段ずつ必要であり、比較的広い表面積を要する沈殿槽を２つも要するため、装置の容積は２段活性汚泥処理法とほとんど違わない大きさを必要としている。
【０００５】
さらに、前記の流動床式生物処理法を用いた２段活性汚泥処理法では、ＢＯＤ等の除去に加えて窒素を同時に除去するために、流動床曝気槽の流出水を嫌気性ろ床槽へ導入し、次いで接触式曝気槽、沈殿槽の順に通すことにより、流動床曝気槽から流出する汚泥の混入した流出水を嫌気性ろ床槽へ導入して、汚泥の嫌気分解消化を進行させるとともに、嫌気性ろ床槽内に充填したろ材に汚泥を捕捉させ、汚泥の流出を止めるとともに、汚泥を捕捉したろ材に排水を接触させることにより排水中の残留有機物をさらに除去し、かつ排水中の窒素分やアンモニア性窒素を亜硝酸や硝酸性窒素に硝化された排水を、嫌気性環境下において有機物の存在下で窒素ガスに還元し、脱窒を行う方法が提案されている。
しかし、この方法では、嫌気性処理槽として嫌気性ろ床槽を用いる関係で、同槽が目詰りしやすく、悪臭の発生が激しいなどの種々の欠点を有する。
【０００６】
【発明が解決しようとする課題】
前述の従来の２段活性汚泥処理法においては、各段の活性汚泥処理において、沈殿槽の設置と汚泥の返送、引き抜きが必要であった。このため、処理プラントが大きくなり、建設費用が高くなる上に、運転管理が煩雑になるという難点があった。また、流動床式生物処理法を先に行う方法では、装置の床面積が大きく、あるいは嫌気性ろ床槽を用いる場合には同槽が目詰りしやすく、操業がむつかしいなどの種々の欠点を有すことは前述したとおりである。
本発明は、上記の従来の２段活性汚泥処理法の問題点に鑑みて成されたものであり、高濃度有機性排水の処理において、２段活性汚泥処理法の第１段目の高負荷槽１段目と２段目の間に必要であった沈殿槽に設置と汚泥の返送、引き抜きによる負担をなくし、運転経費や設備費などが低廉で、容易な運転操作で従来の２段活性汚泥処理法と同等以上の性能を有する処理システムを提供することを目的とするものである。
【０００７】
【課題を解決するための手段】
本発明は、以下の手段により前記課題を解決することができた。
（１）高濃度有機性排水を流動床式生物処理法により処理する第１工程と、第１工程流出水を直接活性汚泥処理法により処理し、その処理水を固液分離により汚泥を分離する第２工程とを組み合せてなり、第１工程である流動床式生物処理法の処理水槽を多槽に区切り、各槽の区切り方を一定の比率で後段側を小さくすることにより、各槽におけるＢＯＤ負荷をほぼ一定に設定して、処理効率を向上させることを特徴とする高濃度有機性排水の処理方法。
（２）高濃度有機性排水を流動床式生物処理法により処理する流動床式生物処理槽と、該生物処理槽から得られる流出水を導入する活性汚泥処理槽と、該活性汚泥処理槽で得られる処理水を固液分離する固液分離装置からなる高濃度有機性排水の処理装置であって、前記生物処理槽は、多槽に区切られており、各槽の区切り方が一定の比率で後段側を小さくした槽からなり、各槽におけるＢＯＤ負荷をほぼ一定に設定することを特徴とする高濃度有機性排水の処理装置。
【０００８】
前記構成のシステムにおいて、高濃度有機性排水を処理する作用について述べると、原水導入手段から流動床式生物処理槽（流動床接触槽ともいう）に供給された原水中の有機物は、処理槽内に入れられた流動可能な担体の表面に付着している微生物の生物学的酸化作用で酸化分解処理される。さらに、流動床式生物処理槽で処理された処理水は、そのまま直接後段処理として活性汚泥処理を実施することによって、残留している有機物が分解され、また曝気液のＳＳは粒径が均一となり、沈殿池では沈降性に優れた汚泥と清澄度の高い上澄水とに分離して、良好な処理水水質が得られる。
なお、本発明における流動床式生物処理槽は、生物処理をする有機性排水中に微生物を担持する粒状等の担体が多数分散していて、前記排水中で流動化している状態にあるものを言い、通常の塔内の上昇気流中に多数の固体粒子が分散流動していて一定の界面以下に固体粒子の流動床を形成しているものとは作用が異なるが、分かり易くするため「流動床式」という。
【０００９】
このように、流動式生物処理槽の処理水を、そのまま直接活性汚泥処理法の曝気法で処理することにより、第１工程の流動床式槽と第２工程の曝気槽の間に第１沈殿槽を設ける廃水処理法や、流動床式曝気槽と接触曝気槽の間に嫌気ろ床槽を設ける含有機排水の処理方法に比べても、全処理工程の処理スペースの大幅なコンパクト化と省エネルギー化が実現できる。
【００１０】
【発明の実施の形態】
以下に、本発明の実施の形態について図面に基づいて説明する。
第１表及び図５は、従来の２段活性汚泥処理法に関するものであり、第３表〜第４表、図２〜４は、本発明の諸実施の形態であり、第２表及び図１は参考例であり、流動床式生物処理法と活性汚泥処理法の組み合わせによる２段生物学的処理法に関するものである。
【００１１】
以下に、本発明の諸実施の形態である２段生物学的処理法について述べる。
なお、実施例、参考例及び比較例を説明するための全図において、同一機能を有するものは同一符号を付け、その繰り返しの説明は省略する。
図１は、参考例に用いられる処理装置の概略構成図である。この処理装置は、流動床式生物処理槽（流動床接触槽）２からなる第１工程に、曝気槽６と沈殿槽８とからなる第２工程が連設されてなるものである。この処理装置においては、第１工程で微生物を担持した担体３を液中に懸濁した懸濁（流動接触）処理法による廃水処理が行われ、第２工程で活性汚泥法による廃水処理が行われる。
なお図１中で、原水１は、流動床式生物処理槽２に入り、その中に分散した担体３と、空気４の導入により流動状態で生物処理され、高い負荷量で処理が行われ、その活性汚泥混合液５は第２工程の曝気槽６に入り、好気性生物処理され、活性汚泥混合液７は沈殿槽８に入り、汚泥が沈殿し、上澄水は処理水９として得られ、沈殿した汚泥の大部分は返送汚泥１０として曝気槽６に戻される。
【００１２】
図２は、実施例１に用いられる２槽式流動床式生物処理と活性汚泥処理を組み合わせた処理装置の概略構成図である。図２中で、２Ａは第１槽であり、２Ｂは第２槽であり、第１槽流出水が第２槽に入るように直列に接続されている。
図３は、実施例２に用いられる４槽式流動床式生物処理と活性汚泥処理を組み合わせた処理装置の概略構成図である。図３中で、２Ａは第１槽、２Ｂは第２槽、２Ｃは第３槽、２Ｄは第４槽であり、第１槽から第４槽まで直列に接続されている。
【００１３】
図４は、図３の４槽式流動床式生物処理槽１の変形例を示す概略説明図である。図４においては、第１槽２Ａは、３つの槽に分割され、第２槽２Ｂは、２つの槽に分割されて、それぞれ処理中の原水が並列に流れるようになっており、第３槽２Ｃと第４槽２Ｄは直列に流れるように直列に接続されている。
この流動接触槽２においては、原水１は、図３の第１槽２Ａを構成する３つの槽のそれぞれに分割して供給され、各槽でそれぞれ並列に懸濁処理法による廃水処理が行われた処理水は、次いで各槽から集められ、その処理水は第２槽２Ｂを構成する２つの槽のそれぞれに分割して供給され、各槽でそれぞれ並列に懸濁処理法による排水処理が行われた処理水は、次いで各槽から集められ、その処理水は第３槽２Ｃに流入し、ここでも同様に排水処理を受けた後、第４槽２Ｄへ流入し、ここでも同様に排水処理を受けた後、第２工程へ供給される。
【００１４】
図５は、従来の２段活性汚泥処理装置の概略構成図である。図５の排水処理装置は、図１の第２工程の活性汚泥処理法を、２段直列に連結したものと見做しうるものである。
原水１は、曝気槽２１に入り、生物学的処理を受け、活性汚泥混合液２２は沈殿槽２３に入り、上澄水２４は第２工程の曝気槽２６に送られ、沈殿槽２３で沈殿した汚泥は返送汚泥２５として曝気槽２１に戻り、第２工程においては、前記の上澄水２４は曝気槽２６でさらに処理され、活性汚泥混合液２７は沈殿槽２８に入り、上澄水は処理水２９として取り出され、沈殿槽２８で沈殿した汚泥は返送汚泥３０として曝気槽２６に戻る。
図１〜４においては、第１工程に流入する原水濃度は、酸素供給に必要な通気攪拌動力が極端に高くならない範囲内において、高い方が省スペースの点から有利であり、ＢＯＤ濃度にして１０００ｍｇ／リットル以上が望ましい。
【００１５】
第１工程である流動床式生物処理槽に入れられる担体は、微生物の付着増殖性、保持性や流動性が得られれば特に限定されない。ただし、容積負荷をできるだけ高く維持できて、しかも有機物の除去性能が高い担体を用いる方が、省スペースの点から有利であることは言うまでもない。使用される担体として、例えば、砂粒、又はプラスチック、ポリウレタン、樹脂、ゴム等の粒状体が挙げられる。微生物の付着性から言って多孔性であることが好ましく、流動性が良くするには比重が１に近いものが好ましい。担体の大きさとしては、微生物の保持性や流動性からいって直径が０．３〜３０ｍｍの範囲程度が好ましい。
【００１６】
本発明の排水処理システムにおいては、第１工程と第２工程の曝気槽の間に沈殿池（槽）を設ける必要がなく、また第１工程流出水を第１工程上流部へ返送させる必要もない。さらに、第２工程で発生した余剰汚泥を第１工程へ戻す必要もない。
第１工程の空気供給手段においては、散気式や機械攪拌式のエアレーション装置が挙げられるが、担体に付着した微生物の保持性や流動性が得られれば特に限定されない。
【００１７】
【実施例】
以下に、従来の２段活性汚泥処理法による処理装置（比較例）、参考例および本発明の流動床式生物処理法と活性汚泥処理法の組み合わせによる２段生物学的処理装置（実施例）を用いて、高濃度有機性排水を処理した実施例について更に詳述する。ただし、本発明はこれらの実施例のみに限定されるものではない。
【００１８】
比較例１
図５の装置を用いて、第１工程である活性汚泥処理装置（曝気槽１０リットル、沈殿槽１５リットル）に対して、食品系有機排水（ＢＯＤ＝１０００ｍｇ／リットル）を、ＢＯＤ容積負荷１０ｋｇ／ｍ³・日で運転して処理した。その結果、ＢＯＤ＝４００ｍｇ／リットルの第１工程流出水が得られた。さらに、第１工程流出水を、第２工程である活性汚泥処理装置（曝気槽４０リットル、沈殿槽１５リットル）に対して、ＢＯＤ容積負荷１ｋｇ／ｍ³・日で運転して処理した結果、ＢＯＤ＝４０ｍｇ／リットルの第２工程流出水が得られた。
処理結果を第１表に示す。
【００１９】
【表１】

【００２０】
参考例
図１の装置を用いて、第１工程である１槽式流動床式生物処理装置（槽容積１０リットル）に対して、食品系有機排水（ＢＯＤ＝１０００ｍｇ／リットル）を、ＢＯＤ容積負荷１０ｋｇ／ｍ³・日で運転して処理した。なお、生物担体としては、ポリウレタン製の担体を、処理水槽の槽容積に対して３０％入れた。その結果、ＢＯＤ＝４００ｍｇ／リットルの第１工程流出水が得られた。さらに、第１工程流出水を第２工程である活性汚泥処理装置（曝気槽４０リットル、沈殿槽１５リットル）に対して、ＢＯＤ容積負荷１ｋｇ／ｍ³・日で運転して処理した結果、ＢＯＤ＝４０ｍｇ／リットルの第２工程流出水が得られた。処理結果を第２表に示す。以上の処理を実施した結果、従来の２段活性汚泥処理法（比較例１）に比べて、槽容積が１９％小さい槽で同等以上の処理能力が得られた。
【００２１】
【表２】

【００２２】
実施例１
図２の装置を用いて、各処理水槽を同一容積（第１槽１０リットル）となるように区切った、２槽式流動床式生物処理装置（第１工程）の第１槽目に対して、食品系有機排水（ＢＯＤ＝１０００ｍｇ／リットル）を、ＢＯＤ容積負荷１０ｋｇ／ｍ³・日で運転し、第２槽目に対して第１槽目流出水（ＢＯＤ＝１００ｍｇ／リットル）を、ＢＯＤ容積負荷４ｋｇ／ｍ³・日で運転して処理した。なお、生物担体としては、ポリウレタン製の担体を、各処理水槽の槽容積に対して３０％充填した。その結果、ＢＯＤ＝４０ｍｇ／リットルの第１工程流出水が得られた。
さらに、同第１工程流出水を第２工程である活性汚泥処理装置（曝気槽４リットル、沈殿槽１５リットル）に対して、ＢＯＤ容積負荷１ｋｇ／ｍ³・日で運転して処理した結果、ＢＯＤ＝４ｍｇ／リットルの第２工程流出水が得られた。結果を第３表に示す。
【００２３】
【表３】

【００２４】
以上の処理を実施した結果、槽容積を従来の２段活性汚泥処理法（比較例１）に比べて５１％、１槽式流動床式生物処理法と活性汚泥処理法の組み合わせによる２段生物学的処理装置（参考例）に比べて、４０％小さい槽で同等以上の処理能力が得られた。
【００２５】
実施例２
図３の装置を用いて、各処理水槽の容積を第１槽目１０リットル、第２槽目４リットル、第３槽目１．６リットル、第４槽目０．６４リットルとなるように区切った、４槽式流動床生物処理装置（第１工程）に対して、食品系有機排水（ＢＯＤ＝１０００ｍｇ／リットル）を第１槽より流入させて、各処理水槽の容積負荷を１０ｋｇ／ｍ³・日で運転して処理した。なお、生物担体としては、ポリウレタン製の担体を、各処理水槽の槽容積に対して３０％入れた。その結果、ＢＯＤ＝２６ｍｇ／リットルの第１工程流出水が得られた。さらに、同第１工程流出水を第２工程である活性汚泥処理装置（曝気槽２．５６リットル、沈殿槽１５リットル）に対して、ＢＯＤ容積負荷１ｋｇ／ｍ³・日で運転して処理した結果、ＢＯＤ＝２．６ｍｇ／リットルの第２工程流出水が得られた。処理結果を第４表に示す。
【００２６】
【表４】

【００２７】
以上の処理を実施した結果、槽容積を従来の２段活性汚泥処理法（比較例１）に比べて５８％、１槽式流動床式生物処理法と活性汚泥処理法の組み合わせによる２段生物学的処理装置（参考例）に比べて４８％、さらに２槽式流動床式生物処理法と活性汚泥処理法の組み合わせによる２段生物学的処理装置（実施例１）に比べて、１３％小さい槽で同等以上の処理能力が得られた。
【００２８】
【発明の効果】
本発明によれば、高濃度有機性排水を流動床式生物処理法により処理する第１工程と、第１工程流出水を活性汚泥処理法により処理する第２工程とを組み合わせた２相生物学的処理法により、全処理工程の処理スペースの大幅なコンパクト化と省エネルギー化が実現できる。
【図面の簡単な説明】
【図１】参考例に用いられる処理装置の概略構成図である。
【図２】本発明の実施例１に用いられる処理装置の概略構成図である。
【図３】本発明の実施例２に用いられる処理装置の概略構成図である。
【図４】図３の４槽式流動床式生物処理槽の一変形列の概略説明図である。
【図５】従来の２段活性汚泥処理装置の概略構成図である。
【符号の説明】
１原水
２流動床式生物処理槽
２Ａ第１槽
２Ｂ第２槽
２Ｃ第３槽
２Ｄ第４槽
３担体
４空気
５活性汚泥混合液
６曝気槽
７活性汚泥混合液
８沈殿槽
９処理水
１０返送汚泥
２１、２６曝気槽
２２、２７活性汚泥混合液
２３、２８沈殿槽
２４上澄水
２５、３０返送汚泥
２９処理水[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a treatment method for high-concentration organic wastewater, and relates to a treatment method that can be treated with high efficiency by reducing the treatment space and saving energy by combining a fluidized bed biological treatment method and an activated sludge method. It is.
[0002]
[Prior art]
The activated sludge treatment method is widely used as a method for biologically treating organic wastewater. In particular, as a treatment method for high-concentration organic wastewater, the first stage is set at a high load and treated. A sludge treatment method (adsorption-activated sludge method: AB method) is widely known. In this two-stage activated sludge treatment method, since the load at the front stage and the rear stage is different, the treatment is performed by the action of the biota different from each stage.
Further, the two-stage activated sludge treatment method will be described in detail. The organic wastewater is oxidized and decomposed in the first stage by microbial treatment mainly consisting of bacteria, and non-aggregating bacteria. This is a treatment method for improving the biological treatment efficiency by precipitating and removing the non-aggregating bacteria in the second stage by microbial treatment mainly consisting of protozoa. Thereby, high-load operation can be performed in the first stage, and the processing efficiency by the activated sludge treatment method can be improved, and at the same time, the amount of surplus sludge generated can be reduced.
[0003]
In recent years, attention has been paid to a treatment using a fluidized bed biological treatment method as the first stage of the two-stage activated sludge treatment. Specifically, the wastewater is first biologically treated in a system in which a microbial carrier is suspended, and sludge is separated and separated in a first sedimentation tank. The primary treated water obtained there is used as activated sludge in the second step. A method of obtaining treated water by sending it to an aerated tank and biologically treating it and precipitating and separating sludge from the effluent from the aerated tank in a second settling tank is known.
[0004]
Further, in this method, the sludge precipitated and separated in the second settling tank is added to the effluent water from the system in which the microorganism carrier is suspended, thereby causing the action of promoting the sludge settling in the first settling tank. I am doing so.
Although this method is highly efficient, it requires two stages each of a combination of a treatment tank and a sedimentation tank, and requires two sedimentation tanks that require a relatively large surface area, so the volume of the apparatus is a two-stage activated sludge treatment method. It needs a size that is almost the same.
[0005]
Furthermore, in the two-stage activated sludge treatment method using the fluidized bed biological treatment method described above, the effluent from the fluidized bed aeration tank is transferred to an anaerobic filter bed tank in order to simultaneously remove nitrogen in addition to removal of BOD and the like. Introduced and then passed through the contact-type aeration tank and then the sedimentation tank in order to introduce the effluent mixed with the sludge flowing out from the fluidized bed aeration tank into the anaerobic filter bed tank to advance the anaerobic digestion of the sludge. In addition, the sludge is trapped by the filter medium filled in the anaerobic filter bed tank, and the outflow of the sludge is stopped, and the wastewater is further removed by bringing the wastewater into contact with the filter medium that has captured the sludge. There has been proposed a method of denitrification by reducing wastewater obtained by nitrifying nitrogen or ammonia nitrogen to nitrous acid or nitrate nitrogen to nitrogen gas in the presence of organic substances in an anaerobic environment.
However, since this method uses an anaerobic filter bed tank as the anaerobic treatment tank, it has various drawbacks such as the tank being easily clogged and generating bad odor.
[0006]
[Problems to be solved by the invention]
In the above-described conventional two-stage activated sludge treatment method, it is necessary to install a sedimentation tank and return and extract the sludge in each stage of activated sludge treatment. For this reason, there existed a difficulty that a processing plant will become large, construction cost will become high, and operation management will become complicated. In addition, the fluidized bed biological treatment method previously has various disadvantages such as a large floor area of the apparatus, or when an anaerobic filter bed tank is used, the tank is easily clogged and operation is difficult. It is as described above.
The present invention has been made in view of the problems of the above-described conventional two-stage activated sludge treatment method, and in the treatment of high-concentration organic wastewater, the first-stage high load of the two-stage activated sludge treatment method. Installation in the sedimentation tank required between the 1st and 2nd stage of the tank, eliminating the burden of returning sludge and pulling out, operating costs and equipment costs are low, and the conventional two-stage activation with easy operation It aims at providing the processing system which has the performance equivalent to or better than the sludge treatment method.
[0007]
[Means for Solving the Problems]
The present invention has solved the above-described problems by the following means.
(1) The first step of treating high-concentration organic wastewater by a fluidized bed biological treatment method, the first step effluent is treated directly by an activated sludge treatment method, and sludge is separated from the treated water by solid-liquid separation. Combined with the second step, the treatment water tank of the fluidized bed biological treatment method that is the first step is divided into multiple tanks, and the separation of each tank is made smaller at a fixed ratio at a fixed ratio, so that in each tank A method for treating high-concentration organic wastewater, characterized in that the treatment efficiency is improved by setting the BOD load substantially constant .
(2) A fluidized bed biological treatment tank for treating high-concentration organic wastewater by a fluidized bed biological treatment method, an activated sludge treatment tank for introducing effluent obtained from the biological treatment tank, and the activated sludge treatment tank. A high-concentration organic wastewater treatment device comprising a solid-liquid separation device that separates the resulting treated water into solid and liquid, wherein the biological treatment tank is divided into multiple tanks, and each tank is divided at a certain ratio. A high-concentration organic wastewater treatment apparatus, characterized in that the rear-stage side is made smaller and the BOD load in each tank is set to be substantially constant.
[0008]
In the system configured as described above, the action of treating high-concentration organic wastewater will be described. The organic matter in the raw water supplied from the raw water introduction means to the fluidized bed biological treatment tank (also referred to as a fluidized bed contact tank) It is oxidatively decomposed by the biological oxidative action of microorganisms adhering to the surface of the flowable carrier placed in the container. Furthermore, the treated water treated in the fluidized bed biological treatment tank is directly subjected to activated sludge treatment as a subsequent treatment, so that the remaining organic matter is decomposed, and the SS of the aeration liquid has a uniform particle size. In the sedimentation basin, it is separated into sludge having excellent sedimentation and supernatant water with high clarity, and a good quality of treated water is obtained.
In the fluidized bed biological treatment tank in the present invention, a large number of particulate carriers carrying microorganisms are dispersed in organic wastewater for biological treatment, and the fluidized in the wastewater. In other words, the action is different from that of a normal tower where a large number of solid particles are dispersed and flowing in an updraft and a fluidized bed of solid particles is formed below a certain interface. It is called “floor type”.
[0009]
Thus, the 1st sedimentation is carried out between the fluid bed type tank of the 1st process, and the aeration tank of the 2nd process by processing the treated water of a fluid type biological treatment tank as it is by the aeration method of an activated sludge processing method as it is. Compared to the wastewater treatment method that provides a tank, and the wastewater treatment method that includes an anaerobic filter bed tank between a fluidized bed aeration tank and a contact aeration tank, the treatment space of all treatment processes is greatly reduced in size and energy is saved. Can be realized.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Table 1 and FIG. 5 relate to a conventional two-stage activated sludge treatment method, and Tables 3 to 4 and FIGS. 2 to 4 are embodiments of the present invention . Reference numeral 1 is a reference example and relates to a two-stage biological treatment method using a combination of a fluidized bed biological treatment method and an activated sludge treatment method.
[0011]
Hereinafter, the two-stage biological treatment method according to embodiments of the present invention will be described.
In all the drawings for explaining the examples , the reference examples, and the comparative examples, those having the same functions are given the same reference numerals, and the repeated explanation thereof is omitted.
FIG. 1 is a schematic configuration diagram of a processing apparatus used in a reference example . In this processing apparatus, a first step consisting of a fluidized bed biological treatment tank (fluidized bed contact tank) 2 is connected to a second step consisting of an aeration tank 6 and a sedimentation tank 8. In this treatment apparatus, waste water treatment is performed by the suspension (fluid contact) treatment method in which the carrier 3 supporting microorganisms is suspended in the liquid in the first step, and waste water treatment is carried out by the activated sludge method in the second step. Is called.
In FIG. 1, raw water 1 enters a fluidized bed biological treatment tank 2, is biologically treated in a fluidized state by introducing a carrier 3 dispersed therein, and air 4, and is processed with a high load. The activated sludge mixed solution 5 enters the aeration tank 6 of the second step and is subjected to the aerobic biological treatment, the activated sludge mixed solution 7 enters the settling tank 8, the sludge is precipitated, and the supernatant water is obtained as the treated water 9, Most of the precipitated sludge is returned to the aeration tank 6 as return sludge 10.
[0012]
FIG. 2 is a schematic configuration diagram of a treatment apparatus that combines the two-tank fluidized bed biological treatment and the activated sludge treatment used in the first embodiment . In FIG. 2, 2A is a 1st tank, 2B is a 2nd tank, and it is connected in series so that a 1st tank effluent may enter a 2nd tank.
FIG. 3 is a schematic configuration diagram of a treatment apparatus that combines the 4-tank fluidized bed biological treatment and the activated sludge treatment used in the second embodiment . In FIG. 3, 2A is a 1st tank, 2B is a 2nd tank, 2C is a 3rd tank, 2D is a 4th tank, and is connected in series from the 1st tank to the 4th tank.
[0013]
FIG. 4 is a schematic explanatory view showing a modification of the 4-tank fluidized bed biological treatment tank 1 of FIG. In FIG. 4, the first tank 2 </ b> A is divided into three tanks, the second tank 2 </ b> B is divided into two tanks, and the raw water being processed flows in parallel, respectively. 2C and 4th tank 2D are connected in series so that it may flow in series.
In this fluid contact tank 2, the raw water 1 is divided and supplied to each of the three tanks constituting the first tank 2A in FIG. 3, and wastewater treatment is performed in parallel in each tank by the suspension treatment method. Then, the treated water is collected from each tank, and the treated water is divided and supplied to each of the two tanks constituting the second tank 2B, and wastewater treatment by the suspension treatment method is performed in parallel in each tank. The treated water is then collected from each tank, and the treated water flows into the third tank 2C, and again receives the waste water treatment, and then flows into the fourth tank 2D. Is supplied to the second step.
[0014]
FIG. 5 is a schematic configuration diagram of a conventional two-stage activated sludge treatment apparatus. The waste water treatment apparatus in FIG. 5 can be regarded as a two-stage serial connection of the activated sludge treatment method in the second step in FIG.
The raw water 1 enters the aeration tank 21, undergoes biological treatment, the activated sludge mixed liquid 22 enters the precipitation tank 23, and the supernatant water 24 is sent to the aeration tank 26 in the second step and settles in the precipitation tank 23. The sludge returns to the aeration tank 21 as return sludge 25. In the second step, the supernatant water 24 is further processed in the aeration tank 26, the activated sludge mixed liquid 27 enters the precipitation tank 28, and the supernatant water is treated water 29. The sludge that has been taken out and settled in the sedimentation tank 28 returns to the aeration tank 26 as a return sludge 30.
In FIGS. 1 to 4, the raw water concentration flowing into the first step is advantageous from the viewpoint of space saving within the range where the aeration stirring power required for supplying oxygen is not extremely high. 1000 mg / liter or more is desirable.
[0015]
The carrier put in the fluidized bed biological treatment tank which is the first step is not particularly limited as long as the microorganisms can be attached and proliferated, retained and fluidized. However, it goes without saying that it is more advantageous from the viewpoint of space saving to use a carrier that can maintain the volumetric load as high as possible and has high organic substance removal performance. Examples of the carrier to be used include sand particles or granular materials such as plastic, polyurethane, resin, and rubber. It is preferably porous in terms of the adhesion of microorganisms, and a specific gravity close to 1 is preferable for improving fluidity. The size of the carrier is preferably in the range of 0.3 to 30 mm in diameter from the viewpoint of microorganism retention and fluidity.
[0016]
In the wastewater treatment system of the present invention, there is no need to provide a settling basin (tank) between the aeration tanks of the first process and the second process, and it is also necessary to return the first process effluent to the upstream part of the first process. Absent. Furthermore, it is not necessary to return the excess sludge generated in the second step to the first step.
Examples of the air supply means in the first step include aeration type and mechanical stirring type aeration apparatuses, but there is no particular limitation as long as the retention and fluidity of microorganisms attached to the carrier can be obtained.
[0017]
【Example】
Hereinafter, a conventional treatment apparatus using a two-stage activated sludge treatment method (comparative example), a reference example, and a two-stage biological treatment apparatus using a combination of the fluidized bed biological treatment method and the activated sludge treatment method of the present invention (Example) The example which processed high concentration organic wastewater using is described in full detail. However, the present invention is not limited to only these examples.
[0018]
Comparative Example 1
5 using the activated sludge treatment apparatus (aeration tank 10 liters, precipitation tank 15 liters), which is the first step, with food-based organic wastewater (BOD = 1000 mg / liter), BOD volumetric load 10 kg / liter. It was processed by driving at m ³ · day. As a result, the first step effluent with BOD = 400 mg / liter was obtained. Furthermore, the first step effluent was processed by treating the activated sludge treatment device (aeration tank 40 liters, settling tank 15 liters) as the second step with a BOD volumetric load of 1 kg / m ³ · day, The second step effluent of BOD = 40 mg / liter was obtained.
The processing results are shown in Table 1.
[0019]
[Table 1]

[0020]
Reference Example Using the apparatus shown in FIG. 1, food-based organic wastewater (BOD = 1000 mg / liter) is applied to the 1-stage fluidized bed biological treatment apparatus (tank volume: 10 liters), which is the first step. Operation was performed at 10 kg / m ³ · day. In addition, as a biological carrier, 30% of polyurethane carrier was added to the tank volume of the treated water tank. As a result, the first step effluent with BOD = 400 mg / liter was obtained. Furthermore, as a result of operating the effluent in the first step on the activated sludge treatment device (aeration tank 40 liters, settling tank 15 liters), which is the second step, at a BOD volumetric load of 1 kg / m ³ · day, = 40 mg / liter of second step effluent was obtained. The processing results are shown in Table 2. As a result of the above treatment, a treatment capacity equal to or higher than that of a conventional two-stage activated sludge treatment method (Comparative Example 1) was obtained in a tank having a tank volume of 19% smaller.
[0021]
[Table 2]

[0022]
Example 1
With respect to the first tank of the two-tank fluidized-bed biological treatment apparatus (first process) in which each treatment water tank is divided to have the same volume (first tank 10 liters) using the apparatus of FIG. The food system organic waste water (BOD = 1000 mg / liter) is operated at a BOD volumetric load of 10 kg / m ³ · day, and the first tank effluent (BOD = 100 mg / liter) is BOD to the second tank. The operation was performed with a volume load of 4 kg / m ³ · day. In addition, as a biological carrier, a carrier made of polyurethane was filled 30% with respect to the tank volume of each treated water tank. As a result, the first step effluent with BOD = 40 mg / liter was obtained.
Furthermore, as a result of operating and treating the first stage effluent with the activated sludge treatment device (aeration tank 4 liters, settling tank 15 liters) as the second process at a BOD volumetric load of 1 kg / m ³ · day, The second step effluent of BOD = 4 mg / liter was obtained. The results are shown in Table 3.
[0023]
[Table 3]

[0024]
As a result of the above treatment, the tank volume is 51% compared with the conventional two-stage activated sludge treatment method (Comparative Example 1), and the two-stage organism is a combination of the one-tank fluidized bed biological treatment method and the activated sludge treatment method. Compared with a biological treatment apparatus ( reference example ), a treatment capacity equal to or higher than that in a 40% smaller tank was obtained.
[0025]
Example 2
Using the apparatus shown in FIG. 3, the volume of each treated water tank is divided so that the first tank is 10 liters, the second tank is 4 liters, the third tank is 1.6 liters, and the fourth tank is 0.64 liters. In addition, food-based organic wastewater (BOD = 1000 mg / liter) is allowed to flow from the first tank into the 4-tank fluidized bed biological treatment apparatus (first step), and the volume load of each treated water tank is 10 kg / m ^3.・ I drove it by day. In addition, as a biological carrier, 30% of a polyurethane carrier was added to the tank volume of each treated water tank. As a result, first step effluent with BOD = 26 mg / liter was obtained. Furthermore, the effluent from the first step was treated with the activated sludge treatment device (aeration tank 2.56 liters, settling tank 15 liters), which was the second step, at a BOD volumetric load of 1 kg / m ³ · day. As a result, second step effluent with BOD = 2.6 mg / liter was obtained. The processing results are shown in Table 4.
[0026]
[Table 4]

[0027]
As a result of the above treatment, the tank volume is 58% compared to the conventional two-stage activated sludge treatment method (Comparative Example 1), and the two-stage organism by combining the one-tank fluidized bed biological treatment method and the activated sludge treatment method. 48% compared to a biological treatment apparatus ( reference example ), and 13% compared to a two-stage biological treatment apparatus ( Example 1 ) using a combination of a two-tank fluidized bed biological treatment method and an activated sludge treatment method. A processing capacity equal to or higher than that in a small tank was obtained.
[0028]
【The invention's effect】
According to the present invention, two-phase biology in which a first step for treating high-concentration organic wastewater by a fluidized bed biological treatment method and a second step for treating first step effluent by an activated sludge treatment method are combined. By using the automatic processing method, the processing space of all processing steps can be greatly reduced in size and energy can be saved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a processing apparatus used in a reference example .
FIG. 2 is a schematic configuration diagram of a processing apparatus used in Embodiment 1 of the present invention.
FIG. 3 is a schematic configuration diagram of a processing apparatus used in Embodiment 2 of the present invention.
4 is a schematic explanatory diagram of a modified row of the 4-tank fluidized bed biological treatment tank of FIG. 3. FIG.
FIG. 5 is a schematic configuration diagram of a conventional two-stage activated sludge treatment apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Raw water 2 Fluidized bed biological treatment tank 2A 1st tank 2B 2nd tank 2C 3rd tank 2D 4th tank 3 Carrier 4 Air 5 Activated sludge mixed liquid 6 Aeration tank 7 Activated sludge mixed liquid 8 Settling tank 9 Treated water 10

Return Sludge

21, 26 Aeration tank 22, 27 Activated sludge mixed

solution

23, 28 Sedimentation tank 24

Supernatant water

25, 30 Return sludge 29 Treated water

Claims

A first step of treating high-concentration organic wastewater by a fluidized bed biological treatment method, and a second step of treating the first step effluent directly by the activated sludge treatment method and separating the sludge by solid-liquid separation of the treated water. The BOD load in each tank is reduced by dividing the treatment water tank of the fluidized bed biological treatment method, which is the first step, into multiple tanks, and reducing the subsequent stage by a fixed ratio in the separation method of each tank. A method for treating high-concentration organic wastewater, characterized in that the treatment efficiency is improved by setting it to be substantially constant .

Fluidized bed biological treatment tank for treating high concentration organic wastewater by fluidized bed biological treatment method, activated sludge treatment tank for introducing effluent water obtained from the biological treatment tank, and treatment obtained in the activated sludge treatment tank A high-concentration organic waste water treatment device comprising a solid-liquid separation device for separating water into solid and liquid, wherein the biological treatment tank is divided into multiple tanks, and the separation of each tank is performed at a fixed ratio at the rear stage side. A processing apparatus for high-concentration organic wastewater, characterized in that the BOD load in each tank is set to be substantially constant.