JP2004041981A - Organic waste water treatment method and its system - Google Patents

Organic waste water treatment method and its system Download PDF

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Publication number
JP2004041981A
JP2004041981A JP2002205364A JP2002205364A JP2004041981A JP 2004041981 A JP2004041981 A JP 2004041981A JP 2002205364 A JP2002205364 A JP 2002205364A JP 2002205364 A JP2002205364 A JP 2002205364A JP 2004041981 A JP2004041981 A JP 2004041981A
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sludge
tank
organic wastewater
stirring
waste water
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Inventor
Katsuji Yoshimi
吉見　勝治
Naoki Ogawa
小川　尚樹
Hirotsugu Nagayasu
長安　弘貢
Masatoshi Tamai
玉井　正俊
Kenichi Katayama
片山　憲一
Ken Matsuo
松尾　　建
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Mitsubishi Heavy Industries Ltd
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Mitsubishi Heavy Industries Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

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  • Activated Sludge Processes (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic waste water treatment method which can increase the concentrations of microorganisms so as to maintain stable treatment performance even at high load. <P>SOLUTION: The organic waste water treatment method is for treating organic waste water by an activated sludge method, and comprises a biological treatment process for agitating the organic waste water together with polyurethane agitation promoting material having an average particle diameter of 4-20 mm and a specific gravity of 1.01-1.10 while aerating, and a sludge separation process where sludge components containing the microorganisms are separated from the treated water after the biological treatment process by sedimentation. An organic waste water treatment system comprises an activated sludge aeration tank containing the polyurethane agitation promoting material and having an agitation means, into which the organic waste water is supplied, a sedimentation tank, and a sludge return line. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、下水や産業排水などの有機性排水の処理方法に関し、さらに詳しくは、排水の種類によらず効果的な生物学的処理を可能にする有機性排水の処理方法に関する。
【０００２】
【従来の技術】
有機性排水の処理において、除去するものとしては有機物（ＢＯＤ，ＣＯＤ）、窒素化合物、リン化合物などが挙げられる。従来、有機性排水については、衛生処理、水質保全を主目的として、先ず、ＢＯＤ成分について微生物による活性汚泥処理（活性汚泥法）が行われ、例えば硝化脱窒素処理では同時に窒素化合物についても処理を行う。次いで、ＢＯＤ成分や窒素化合物が除去された排水は、高度処理等により、ＣＯＤ成分、リン化合物あるいは色度等が除去される。
【０００３】
これまで、生物（活性汚泥）による有機性排水処理では、有機物の負荷が上昇すると、汚泥が膨化（バルキング）あるいは解体することにより、微生物を含む汚泥成分と処理水との固液分離が困難になり処理が破綻するという問題があった。そのため、処理に用いる微生物の処理能力から、有機物の負荷は０．４ｋｇ−ＢＯＤ／ｋｇ−ＭＬＳＳ／ｄ程度で運転するのが一般的であった。多量の排水処理を行う場合には、微生物の絶対量を増加させて、その分処理槽の容量を大きくしなければならないのが生物処理法の欠点となっていた。ここで、０．４ｋｇ−ＢＯＤ／ｋｇ−ＭＬＳＳ／ｄとは、活性汚泥１ｋｇ当たりに処理させるＢＯＤの量を示した数値であり、この場合には、１日に活性汚泥１ｋｇあたり０．４ｋｇのＢＯＤを供給するということである。
【０００４】
汚泥の膨化（バルキング）には、幾つかの種類がある。一般に汚泥が膨化する現象をバルキングというが、処理物が過負荷であることによるバルキングの他、糸状菌が増加して汚泥が浮いてしまう現象もバルキングといい、後者を糸状性バルキングといい、ネット状に汚泥が浮いてしまうような状態になる。
従来、糸状性バルキングの防止方法として、例えば、活性汚泥曝気槽のバルキング防止のために、沈降性の粒状固形担体（比重１．５〜７、径５〜１００μｍ程度のもの）とカチオン系またはノニオン系高分子凝集剤を添加する、粒状固形担体の添加方法が知られている。しかしながら、このような粒径が小さな担体を添加した場合、担体の一部が添加時にＳＳとして処理水に流出するため、処理水の悪化を招いてしまう。また、それを防止するために高分子凝集剤を添加する態様では、ランニングコストの上昇につながり、実用性が乏しい。
【０００５】
また、活性汚泥の改良方法として、活性汚泥曝気槽中に平均粒径１〜４ｍｍの浮上性の合成樹脂製粒状体を曝気槽全量に対し１０〜４０％（体積Ｖｏｌ）添加することによりバルキングを防止する方法が知られている。しかしながら、この方法では、浮上性の合成樹脂を用いているため、表面の撹拌効果しか期待できず、また強度の問題から酸素溶解効率の高い機械式撹拌装置を使用することが難しい。
そして、上記二つの方法は、主に糸状性バルキングを対象にしており、糸状性菌を伴わない過負荷によるバルキングや汚泥解体については、未だ十分な研究がなされていなかった。
【０００６】
一方、排水の生物学的処理方法においては、通常、排水中の微生物はフロック（微生物の固まり、１００ミクロン程度）を作って、ある程度バラバラの状態で存在している。そこで、曝気槽中における微生物の濃度を増大させて処理能力を向上させるべく、曝気槽中に付着担体を添加するという方法が知られている。とこらが、担体を多量に投入しても微生物の付着量には限界があり、排水の処理能力向上には十分でない。また、微生物の付着性に優れた担体を用いるとしても、曝気槽内での攪拌や曝気等の他の条件にも好適な材料を選定することは困難であった。
【０００７】
【発明が解決しようとする課題】
本発明者らは、上記問題点に鑑み、高負荷でも安定した処理性能を維持できるように、微生物濃度を上げることが可能であり、かつ、汚泥の沈降性が向上して後段での汚泥分離が容易な排水処理法を開発すべく、鋭意検討した。
その結果、本発明者らは、活性汚泥曝気槽と沈殿槽との組み合わせからなるシステムにおいて、曝気槽に特定の攪拌促進材を添加することによって、かかる問題点が一気に解決されることを見出した。
本発明は、かかる見地より完成されたものである。
【０００８】
【課題を解決するための手段】
すなわち、本発明は、活性汚泥法による有機性排水の処理方法であって、有機性排水を、平均粒径４〜２０ｍｍ、比重１．０１〜１．１０のポリウレタン製攪拌促進材とともに曝気しながら攪拌処理する、生物学的処理工程と、該生物学的処理工程を経た処理水から、微生物を含む汚泥成分を沈降によって分離する、汚泥分離工程と、を含む有機性排水の処理方法を提供するものである。本発明では、さらに加えて、前記汚泥分離工程にて分離された汚泥成分を、前記生物学的処理工程に返送して、有機性排水とともに供給する、汚泥返送工程、を含む態様が好適である。
前記生物学的処理工程においては、攪拌促進材を通常５〜３０容量％の範囲で添加することが好ましい。前記攪拌促進材としては、例えば、直径５〜１０ｍｍ好ましくは直径６〜８ｍｍ、長さ５〜１２ｍｍ好ましくは長さ７〜９ｍｍの筒状体を用いることができる。これら攪拌促進材は、生物学的処理工程において繰り返し用いられることが好ましく、例えば後段の汚泥分離工程に送られる処理水中に含まれないように、スクリーン等で流下しないようにするのがよい。
【０００９】
また、本発明は、ポリウレタン製攪拌促進材を含む槽内に有機性排水が供給されるとともに、槽内に攪拌手段を備える、活性汚泥曝気槽と、該活性汚泥曝気槽から送られる処理水を貯えて、微生物を含む汚泥成分を沈降によって分離する、沈澱槽と、該沈殿槽において分離された該汚泥成分を、前記活性汚泥曝気槽に返送する、汚泥返送ラインと、を含む有機性排水の処理システムを提供するものである。ここで前記攪拌手段としては、具体的には、槽内の排水に空気を供給する水中エアレーターもしくは散気管などを用いることができる。また攪拌手段としては、攪拌工程のみを行う機械式攪拌器装置を備え、別途、空気供給手段として散気管もしくは水中エアレーターを備える態様も可能である。
また、活性汚泥曝気槽には、後段の沈澱槽に送られる処理水中に攪拌促進材が含まれないように、攪拌促進材を通さない大きさの網目状あるいは格子状等のスクリーンが設置されていることが好ましい。
【００１０】
本発明の処理対象である有機性排水としては、例えば下水や産業排水などが挙げられる。
【００１１】
【発明の実施の形態】
以下、本発明に係る有機性排水の処理方法について、添付図面を参照しながらその具体的な実施形態を詳細に説明する。
図１および図２に、本発明の有機性排水の処理システムの一例を模式的に示す。本実施の形態のシステムでは、活性汚泥曝気槽１、沈澱槽６および汚泥返送ライン１０を備えている。
【００１２】
活性汚泥曝気槽１は、槽内にポリウレタン製攪拌促進材５を含み、原水である有機性排水が供給される。槽内には、図１では攪拌手段として散気管２が曝気ブロア３と接続して備えられており、図２では攪拌手段として水中エアレーター８が曝気ブロア３と接続して備えられている。ここで、当該散気管２および水中エアレーター８は、共に槽内の排水に空気を供給する空気供給手段としての役割も担っている。本発明で用いるポリウレタン製攪拌促進材５は、水中エアレーターなどの機械式攪拌器による回転作用を受けても、剪断したり破壊したりすることがなく、攪拌による作用を直接効果的に有機性排水に伝播することが可能であり、攪拌効果を促進することができる。
【００１３】
なお、本発明では、図１および図２には図示していない機械式攪拌器を槽内に設けてもよい。この場合には、回旋翼等を有する機械式攪拌器が主に攪拌の役割を担い、散気管２および水中エアレーター８は、主に空気供給手段としての役割を担うこととなる。
【００１４】
前記ポリウレタン製攪拌促進材５としては、平均粒径４〜２０ｍｍ、比重１．０１〜１．１０のものが用いられる。具体的には例えば、直径５〜１０ｍｍ好ましくは直径６〜８ｍｍ、長さ５〜１２ｍｍ好ましくは長さ７〜９ｍｍの筒状体を用いることが好適である。この攪拌促進材５は、活性汚泥曝気槽１内において通常５〜３０容量％の範囲で添加されていることが好ましい。
【００１５】
曝気槽１には、後段の沈澱槽６に送られる処理水中に攪拌促進材５が含まれないように、攪拌促進材５を通さない程度の大きさの網目状あるいは格子状のスクリーン４が設置されている。このスクリーンとして具体的には、３ｍｍ以上の粒子が透過しないバースクリーン等が用いられる。
【００１６】
活性汚泥曝気槽１においては、有機性排水をポリウレタン製攪拌促進材とともに曝気しながら攪拌処理する。槽内では、底部付近に設けられた散気管２もしくは水中エアレーター８から空気を供給しながら、好気的な条件下で有機性排水を微生物によって処理する。この生物学的処理工程で排水中の有機物は微生物により資化、分解されて、一部は微生物菌体となり、汚泥を形成する。
【００１７】
次いで、曝気槽１からの汚泥を含んだ処理水は、後段の沈殿槽６に送られる。沈澱槽６では、活性汚泥曝気槽１からの処理水を静置して、微生物を含む汚泥成分を沈降させて、上澄み液と汚泥を分離する。上澄み液は、そのまま放流される場合もあるが、さらなる高度処理を経てから放流される場合もある。
【００１８】
本発明の処理方法では、高負荷の有機性排水処理を行っても、この沈殿槽６における汚泥分離工程では、上澄み液と汚泥成分との分離が良好に行われる。この沈殿槽６で固液分離された汚泥成分は、汚泥返送ポンプ７を経て汚泥返送ライン１０によって活性汚泥曝気槽１に返送される。
【００１９】
図３および図４には、本発明に用いる攪拌促進材５を用いた場合、および、攪拌促進材５を用いなかった場合、それぞれを比較した実験結果を示す。
試験条件は、有機性排水である原水のＢＯＤ値が１６００ｍｇ／リットル、曝気槽容量５０リットルであった。攪拌促進材を１０容量％添加した場合（◆）のＢＯＤ容積負荷は１〜１０ｋｇ／ｍ３／ｄであり、添加しなかった場合（□）のＢＯＤ容積負荷は１〜６ｋｇ／ｍ３／ｄであった。
この結果から明らかなように、３０分静置した後の汚泥沈降性（ＳＶ３０）は、攪拌促進材を添加することによって極めて良好になる（図３参照）。また、ＢＯＤ容積負荷との関係から、本発明の攪拌促進材を添加すれば有機性排水量が多くなってもＳＶＩ（ｍｌ／ｇ−ＭＬＳＳ）が１５０以下であり、運転可能であることがわかる（図４参照）。
【００２０】
本発明の処理方法および処理システムは種々の設備に適宜用いることができ、何ら限定されるものではないが、例えば、一槽式硝化脱窒処理槽（単一槽）に好適に用いることができる。
【００２１】
一般に生物脱窒法では、曝気で作った好気雰囲気下、排水に含まれているアンモニア性窒素を硝化菌の作用により、亜硝酸性窒素または硝酸性窒素に酸化する硝化反応と、かかる亜硝酸性窒素または硝酸性窒素を脱窒菌の作用により、嫌気雰囲気下窒素ガスに還元する脱窒反応によって行われる。この生物脱窒法の重要な役割を担っているのは硝化菌と脱窒菌であるが、二槽式装置ではこれらの菌が機能するために、好気雰囲気下の硝化反応と、嫌気雰囲気下の脱窒反応とは、硝化槽と脱窒槽において別々に行われる。
【００２２】
これに対し、単一槽タイプの装置で処理を行う場合においては、曝気槽１にて、高い活性汚泥濃度・容積負荷に設定した、ＢＯＤ成分を含んだ有機性排水を間欠投入すること、曝気空気量を過不足ないように制御すること等により、アンモニア性窒素の硝化を亜硝酸性窒素までで止めると共に、単一の反応槽で硝化反応と脱窒反応とを同時に行い、反応効率を高める。
【００２３】
本方法では、被処理排水を間欠投入するにより、有機性排水の投入時には、排水の高い酸素消費活性を利用することにより槽内を比較的嫌気状態にして脱窒反応が卓越する時間帯を確保し、投入停止時には、槽内を比較的好気状態に維持し硝化反応が卓越する時間帯を確保する。また、溶存酸素濃度を必要以上に高くしない様にするために、曝気空気量を過不足ないように制御することで、曝気を行いつつ嫌気環境をつくり、高い脱窒機能を維持する。このような単一槽は、プロセスを簡易化でき、かつ、ｐＨ調整用アルカリの薬品の使用量を少なくできるという利点がある。
そして、上記単一槽からの流出液は、単一槽に接続している沈殿槽６に導入され、沈降等の汚泥分離手段により固液分離し、上澄み液を取出し、汚泥成分を単一槽に返送する。単一槽において高負荷で処理を行う場合、活性汚泥濃度を高く維持する必要があり、本発明の処理方法が好適に用いられる。
【００２４】
本発明の処理方法においては、沈殿槽６の後段において、必要に応じて高度処理を実施することができる。
高度処理では、凝集沈殿・活性炭吸着・オゾン処理などにより、生物処理で残留した有機物（ＣＯＤ成分）や色度（着色成分）、リンなどの除去を行う。
【００２５】
【発明の効果】
本発明に係る処理方法によれば、高負荷でも安定した処理性能を維持できるように、微生物濃度を上げることが可能な排水処理法を提供できる。これにより、装置を小型化することやシステムの運転コストを低減することができる。
【図面の簡単な説明】
【図１】本発明に係る有機性排水の処理システムの一例を模式的に示す図である。
【図２】本発明に係る有機性排水の処理システムの他の一例を模式的に示す図である。
【図３】攪拌促進材による、汚泥の沈降性に与える影響を示すグラフである。
【図４】攪拌促進材による、ＢＯＤ容積負荷に与える影響を示すグラフである。
【符号の説明】
１　曝気槽
２　散気管
３　曝気ブロア
４　スクリーン
５　攪拌促進材
６　沈殿槽
７　汚泥返送ポンプ
８　水中エアレーター
１０　汚泥返送ライン[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for treating organic wastewater such as sewage and industrial wastewater, and more particularly, to a method for treating organic wastewater that enables effective biological treatment regardless of the type of wastewater.
[0002]
[Prior art]
In the treatment of organic wastewater, organic substances (BOD, COD), nitrogen compounds, phosphorus compounds and the like can be mentioned as those to be removed. Conventionally, for organic wastewater, BOD components are first subjected to activated sludge treatment by microorganisms (activated sludge method) for the main purpose of sanitary treatment and water quality conservation. For example, in nitrification denitrification treatment, nitrogen compounds are also treated at the same time. Do. Next, the COD component, the phosphorus compound, the chromaticity, and the like are removed from the waste water from which the BOD component and the nitrogen compound have been removed by advanced treatment or the like.
[0003]
Until now, in organic wastewater treatment by living organisms (activated sludge), when the load of organic matter rises, the sludge expands (bulks) or disintegrates, making it difficult to separate solid and liquid from sludge components containing microorganisms and treated water. There was a problem that the processing failed. For this reason, it was common to operate at a load of organic matter of about 0.4 kg-BOD / kg-MLSS / d from the processing ability of the microorganisms used for the treatment. When performing a large amount of wastewater treatment, it is a drawback of the biological treatment method that the absolute amount of microorganisms must be increased and the capacity of the treatment tank must be increased accordingly. Here, 0.4 kg-BOD / kg-MLSS / d is a numerical value indicating the amount of BOD to be treated per kg of activated sludge. In this case, 0.4 kg / kg of activated sludge per day is used. Supplying the BOD.
[0004]
There are several types of bulking of sludge. In general, the phenomenon of sludge swelling is called bulking, but in addition to bulking due to overloading of the processed material, the phenomenon in which filamentous fungi increase and sludge floats is also called bulking, and the latter is called filamentous bulking. It becomes a state where sludge floats in a shape.
Conventionally, as a method for preventing filamentous bulking, for example, in order to prevent bulking in an activated sludge aeration tank, a settling granular solid carrier (specific gravity of 1.5 to 7, having a diameter of about 5 to 100 μm) and a cationic or nonionic solid carrier are used. There is known a method for adding a granular solid carrier in which a system polymer flocculant is added. However, when a carrier having such a small particle size is added, a part of the carrier flows out into the treated water as SS at the time of addition, so that the treated water is deteriorated. In addition, in a mode in which a polymer coagulant is added to prevent this, running costs are increased and practicality is poor.
[0005]
In addition, as a method for improving activated sludge, bulking is performed by adding 10 to 40% (volume Vol) of buoyant synthetic resin granules having an average particle diameter of 1 to 4 mm to the total amount of the aeration tank in the activated sludge aeration tank. Methods to prevent this are known. However, in this method, since a floating synthetic resin is used, only a surface stirring effect can be expected, and it is difficult to use a mechanical stirrer having high oxygen dissolving efficiency due to a problem of strength.
The above two methods are mainly intended for filamentous bulking, and bulking and sludge disintegration due to overload without filamentous bacteria have not yet been sufficiently studied.
[0006]
On the other hand, in a biological treatment method for wastewater, microorganisms in the wastewater usually form flocs (lump of microorganisms, about 100 microns) and exist in a state of being dispersed to some extent. Therefore, there is known a method of adding an adhering carrier to an aeration tank in order to increase the concentration of microorganisms in the aeration tank and improve the treatment capacity. However, even if a large amount of carrier is introduced, the amount of microorganisms attached is limited, and is not sufficient for improving the treatment capacity of wastewater. Further, even if a carrier having excellent adhesion of microorganisms is used, it is difficult to select a material suitable for other conditions such as stirring and aeration in an aeration tank.
[0007]
[Problems to be solved by the invention]
In view of the above problems, the present inventors have found that it is possible to increase the concentration of microorganisms so that stable treatment performance can be maintained even under high load, and that the sedimentation of sludge is improved, and We studied diligently to develop a wastewater treatment method that is easy to use.
As a result, the present inventors have found that in a system composed of a combination of an activated sludge aeration tank and a settling tank, such a problem can be solved at once by adding a specific stirring promoting material to the aeration tank. .
The present invention has been completed from such a viewpoint.
[0008]
[Means for Solving the Problems]
That is, the present invention relates to a method for treating organic wastewater by the activated sludge method, wherein the organic wastewater is aerated with an agitation accelerator made of polyurethane having an average particle size of 4 to 20 mm and a specific gravity of 1.01 to 1.10. Provided is a method for treating organic wastewater, comprising: a biological treatment step of performing a stirring treatment; and a sludge separation step of separating sludge components containing microorganisms from treated water that has passed through the biological treatment step by sedimentation. Things. In the present invention, a mode in which the sludge component separated in the sludge separation step is returned to the biological treatment step and supplied together with the organic wastewater, and a sludge return step is preferable. .
In the biological treatment step, it is preferable to add a stirring promoter in a range of usually 5 to 30% by volume. As the stirring promoting material, for example, a cylindrical body having a diameter of 5 to 10 mm, preferably 6 to 8 mm, and a length of 5 to 12 mm, preferably 7 to 9 mm can be used. These agitation promoting materials are preferably used repeatedly in the biological treatment step. For example, it is preferable not to flow down by a screen or the like so as not to be contained in the treated water sent to the subsequent sludge separation step.
[0009]
Further, the present invention provides an activated sludge aeration tank provided with stirring means in the tank while the organic wastewater is supplied into the tank containing the polyurethane agitation accelerator, and treated water sent from the activated sludge aeration tank. Storing and separating a sludge component containing microorganisms by sedimentation, a settling tank, and returning the sludge component separated in the settling tank to the activated sludge aeration tank; A processing system is provided. Here, as the stirring means, specifically, an underwater aerator or a diffuser pipe for supplying air to the drainage in the tank can be used. Further, a mode in which a mechanical stirrer device for performing only the stirring step is provided as the stirring means and a diffuser or a submersible aerator is separately provided as the air supply means is also possible.
Further, the activated sludge aeration tank is provided with a mesh-like or grid-like screen that is not permeable to the agitation promoting material so that the agitation promoting material is not included in the treated water sent to the subsequent settling tank. Is preferred.
[0010]
Examples of the organic wastewater to be treated in the present invention include sewage and industrial wastewater.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a specific embodiment of the method for treating organic wastewater according to the present invention will be described in detail with reference to the accompanying drawings.
1 and 2 schematically show an example of the organic wastewater treatment system of the present invention. The system of the present embodiment includes an activated sludge aeration tank 1, a settling tank 6, and a sludge return line 10.
[0012]
The activated sludge aeration tank 1 includes a polyurethane agitation promoting material 5 in the tank, and is supplied with organic wastewater as raw water. In the tank, a diffuser tube 2 is provided as a stirring means in FIG. 1 in connection with the aeration blower 3, and in FIG. 2, a submersible aerator 8 is provided as a stirring means in connection with the aeration blower 3. Here, the air diffuser 2 and the underwater aerator 8 also serve as air supply means for supplying air to drainage in the tank. The polyurethane agitation promoting material 5 used in the present invention does not shear or break even when subjected to a rotating action by a mechanical agitator such as a submersible aerator, and the effect of the agitation can be directly and organically effective. It can propagate to drainage and promote the stirring effect.
[0013]
In the present invention, a mechanical stirrer not shown in FIGS. 1 and 2 may be provided in the tank. In this case, a mechanical stirrer having a rotating blade or the like mainly plays a role of stirring, and the diffuser tube 2 and the underwater aerator 8 mainly play a role of air supply means.
[0014]
As the polyurethane agitation accelerator 5, those having an average particle size of 4 to 20 mm and a specific gravity of 1.01 to 1.10. Specifically, for example, it is preferable to use a cylindrical body having a diameter of 5 to 10 mm, preferably 6 to 8 mm, and a length of 5 to 12 mm, preferably 7 to 9 mm. It is preferable that the stirring promoting material 5 is added in the activated sludge aeration tank 1 in a range of usually 5 to 30% by volume.
[0015]
The aeration tank 1 is provided with a mesh-like or grid-like screen 4 large enough to prevent the stirring promoting material 5 from passing through the treated water sent to the subsequent settling tank 6. Have been. Specifically, a bar screen through which particles of 3 mm or more do not pass is used as the screen.
[0016]
In the activated sludge aeration tank 1, the organic wastewater is agitated while being aerated with a polyurethane agitation accelerator. In the tank, the organic wastewater is treated with microorganisms under aerobic conditions while supplying air from the air diffuser 2 or the underwater aerator 8 provided near the bottom. In this biological treatment step, the organic matter in the wastewater is assimilated and decomposed by microorganisms, and part of the organic matter becomes microbial cells to form sludge.
[0017]
Next, the treated water containing the sludge from the aeration tank 1 is sent to the subsequent settling tank 6. In the sedimentation tank 6, the treated water from the activated sludge aeration tank 1 is allowed to stand still to settle sludge components containing microorganisms, thereby separating the supernatant liquid and sludge. The supernatant liquid may be discharged as it is, or may be discharged after further advanced treatment.
[0018]
In the treatment method of the present invention, even when a high-load organic wastewater treatment is performed, in the sludge separation step in the sedimentation tank 6, the supernatant liquid and the sludge component are favorably separated. The sludge component solid-liquid separated in the sedimentation tank 6 is returned to the activated sludge aeration tank 1 by a sludge return line 10 via a sludge return pump 7.
[0019]
FIG. 3 and FIG. 4 show experimental results comparing the case where the stirring promoting material 5 used in the present invention was used and the case where the stirring promoting material 5 was not used.
The test conditions were that the BOD value of raw water as organic wastewater was 1600 mg / liter, and the capacity of the aeration tank was 50 liters. When 10% by volume of the stirring promoter is added (◆), the BOD volume load is 1 to 10 kg / m 3 / d, and when not added (□), the BOD volume load is 1 to 6 kg / m 3 / d. Met.
As is clear from these results, the sludge settling property (SV30) after standing for 30 minutes is extremely improved by adding the stirring promoter (see FIG. 3). In addition, from the relationship with the BOD volume load, it can be seen that the addition of the agitation promoting material of the present invention has an SVI (ml / g-MLSS) of 150 or less and can be operated even when the amount of organic wastewater is large ( (See FIG. 4).
[0020]
The treatment method and treatment system of the present invention can be appropriately used for various facilities and are not limited at all. For example, the treatment method and treatment system can be suitably used for a single-tank nitrification and denitrification treatment tank (single tank). .
[0021]
In general, in the biological denitrification method, under the aerobic atmosphere created by aeration, the nitrification reaction that oxidizes ammonia nitrogen contained in wastewater to nitrite nitrogen or nitrate nitrogen by the action of nitrifying bacteria, It is performed by a denitrification reaction in which nitrogen or nitrate nitrogen is reduced to nitrogen gas under an anaerobic atmosphere by the action of a denitrifying bacterium. Nitrifying bacteria and denitrifying bacteria play an important role in this biological denitrification method.However, these bacteria function in a two-tank type device. The denitrification reaction is performed separately in the nitrification tank and the denitrification tank.
[0022]
On the other hand, when the treatment is performed by a single-tank type apparatus, the organic wastewater containing the BOD component, which is set to a high activated sludge concentration and volume load, is intermittently charged in the aeration tank 1, By controlling the amount of air so that there is no excess or deficiency, nitrification of ammonia nitrogen is stopped at nitrite nitrogen, and nitrification and denitrification reactions are simultaneously performed in a single reaction tank to increase reaction efficiency. .
[0023]
In this method, the wastewater to be treated is intermittently charged, and when the organic wastewater is charged, the inside of the tank is made relatively anaerobic by using the high oxygen consumption activity of the wastewater to secure a time zone in which the denitrification reaction is dominant. However, when the charging is stopped, the inside of the tank is maintained in a relatively aerobic state to secure a time zone in which the nitrification reaction is dominant. In addition, in order to prevent the dissolved oxygen concentration from becoming unnecessarily high, the amount of aerated air is controlled so as not to be excessive or insufficient, thereby creating an anaerobic environment while performing aeration and maintaining a high denitrification function. Such a single tank has an advantage that the process can be simplified and the amount of the alkali chemical for pH adjustment can be reduced.
The effluent from the single tank is introduced into the sedimentation tank 6 connected to the single tank, and is separated into solid and liquid by sludge separation means such as sedimentation, and the supernatant is taken out. Return to. When treating with a high load in a single tank, the activated sludge concentration needs to be kept high, and the treatment method of the present invention is suitably used.
[0024]
In the treatment method of the present invention, an advanced treatment can be performed as necessary in the latter stage of the precipitation tank 6.
In the advanced treatment, organic matter (COD component), chromaticity (coloring component), phosphorus, and the like remaining in the biological treatment are removed by coagulation sedimentation, activated carbon adsorption, ozone treatment, and the like.
[0025]
【The invention's effect】
According to the treatment method of the present invention, a wastewater treatment method capable of increasing the concentration of microorganisms can be provided so that stable treatment performance can be maintained even under a high load. As a result, the size of the apparatus can be reduced and the operating cost of the system can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing an example of an organic wastewater treatment system according to the present invention.
FIG. 2 is a diagram schematically showing another example of the organic wastewater treatment system according to the present invention.
FIG. 3 is a graph showing the effect of the stirring promoter on the sedimentation of sludge.
FIG. 4 is a graph showing the effect of a stirring enhancer on the BOD volume load.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Aeration tank 2 Aeration tube 3 Aeration blower 4 Screen 5 Stirrer 6 Sedimentation tank 7 Sludge return pump 8 Underwater aerator 10 Sludge return line

Claims (7)

活性汚泥法による有機性排水の処理方法であって、
有機性排水を、平均粒径４〜２０ｍｍ、比重１．０１〜１．１０のポリウレタン製攪拌促進材とともに曝気しながら攪拌処理する、生物学的処理工程と、
該生物学的処理工程を経た処理水から、微生物を含む汚泥成分を沈降によって分離する、汚泥分離工程と、
を含む有機性排水の処理方法。A method for treating organic wastewater by an activated sludge method,
A biological treatment step of agitating the organic wastewater while aerating it with a polyurethane stirring accelerator having an average particle size of 4 to 20 mm and a specific gravity of 1.01 to 1.10.
From the treated water that has passed through the biological treatment step, a sludge component containing microorganisms is separated by settling, a sludge separation step,
Of wastewater containing organic wastewater. さらに加えて、前記汚泥分離工程にて分離された汚泥成分を、前記生物学的処理工程に返送して、有機性排水とともに供給する、汚泥返送工程、を含むことを特徴とする請求項１記載の処理方法。The method according to claim 1, further comprising a sludge return step of returning the sludge component separated in the sludge separation step to the biological treatment step and supplying the sludge component together with organic wastewater. Processing method. 前記生物学的処理工程において、攪拌促進材を５〜３０容量％添加することを特徴とする請求項１又は２に記載の処理方法。3. The method according to claim 1, wherein in the biological treatment step, a stirring promoting material is added in an amount of 5 to 30% by volume. 4. 前記攪拌促進材として、直径５〜１０ｍｍ、長さ５〜１２ｍｍの筒状体を用いることを特徴とする請求項１〜３のいずれかに記載の有機性排水の処理方法。The method according to any one of claims 1 to 3, wherein a cylindrical body having a diameter of 5 to 10 mm and a length of 5 to 12 mm is used as the stirring promoting material. ポリウレタン製攪拌促進材を含む槽内に有機性排水が供給されるとともに、槽内に攪拌手段を備える、活性汚泥曝気槽と、
該活性汚泥曝気槽から送られる処理水を貯えて、微生物を含む汚泥成分を沈降によって分離する、沈澱槽と、
該沈殿槽において分離された該汚泥成分を、前記活性汚泥曝気槽に返送する、汚泥返送ラインと、
を含むことを特徴とする有機性排水の処理システム。An organic sludge is supplied into a tank containing a stirring agitation material made of polyurethane, and the tank is provided with a stirring means in the tank.
A sedimentation tank for storing treated water sent from the activated sludge aeration tank and separating sludge components containing microorganisms by sedimentation;
A sludge return line for returning the sludge component separated in the settling tank to the activated sludge aeration tank,
An organic wastewater treatment system comprising: 前記攪拌手段が、槽内の排水に空気を供給する水中エアレーターもしくは散気管であることを特徴とする請求項５記載の有機性排水の処理システム。6. The organic wastewater treatment system according to claim 5, wherein the stirring means is an underwater aerator or a diffuser for supplying air to the wastewater in the tank. 前記攪拌手段が、槽内に設けられる機械式攪拌器であるとともに、空気供給手段として水中エアレーターもしくは散気管を備えることを特徴とする請求項４記載の有機性排水の処理システム。The organic wastewater treatment system according to claim 4, wherein the stirring means is a mechanical stirrer provided in a tank, and further includes a submersible aerator or a diffuser as an air supply means.
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007196105A (en) * 2006-01-25 2007-08-09 Maezawa Kasei Ind Co Ltd Apparatus for treating wastewater such as dye wastewater
EP2039659A1 (en) * 2006-07-06 2009-03-25 Hitachi Plant Technologies, Ltd. Inclusive immobilization support, wastewater disposal apparatus and wastewater disposal method using the inclusive immobilization support
US7816110B2 (en) 2005-12-15 2010-10-19 Hitachi Plant Technologies, Ltd. Process for producing pellets containing entrapped microorganisms
CN105621603A (en) * 2016-01-05 2016-06-01 长沙奥邦环保实业有限公司 Returned sludge elutriation process of biological sewage treatment system
CN108726819A (en) * 2018-08-13 2018-11-02 碧沃丰工程有限公司 A kind of device of purification river black and odorous water
CN113939480A (en) * 2019-08-21 2022-01-14 株式会社杰·菲尔兹 Sludge drainage treatment equipment and treatment method thereof
CN115259337A (en) * 2021-04-30 2022-11-01 辽河石油勘探局有限公司 High-polymer-content heavy oil sewage deep aeration treatment system

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7816110B2 (en) 2005-12-15 2010-10-19 Hitachi Plant Technologies, Ltd. Process for producing pellets containing entrapped microorganisms
JP2007196105A (en) * 2006-01-25 2007-08-09 Maezawa Kasei Ind Co Ltd Apparatus for treating wastewater such as dye wastewater
EP2039659A1 (en) * 2006-07-06 2009-03-25 Hitachi Plant Technologies, Ltd. Inclusive immobilization support, wastewater disposal apparatus and wastewater disposal method using the inclusive immobilization support
EP2039659A4 (en) * 2006-07-06 2012-01-25 Hitachi Plant Technologies Ltd Inclusive immobilization support, wastewater disposal apparatus and wastewater disposal method using the inclusive immobilization support
CN105621603A (en) * 2016-01-05 2016-06-01 长沙奥邦环保实业有限公司 Returned sludge elutriation process of biological sewage treatment system
CN105621603B (en) * 2016-01-05 2018-06-26 长沙奥邦环保实业有限公司 Sewage biological treatment system returned sludge eluriates technique
CN108726819A (en) * 2018-08-13 2018-11-02 碧沃丰工程有限公司 A kind of device of purification river black and odorous water
CN108726819B (en) * 2018-08-13 2024-03-26 碧沃丰工程有限公司 Device for purifying black and odorous water body of river channel
CN113939480A (en) * 2019-08-21 2022-01-14 株式会社杰·菲尔兹 Sludge drainage treatment equipment and treatment method thereof
CN115259337A (en) * 2021-04-30 2022-11-01 辽河石油勘探局有限公司 High-polymer-content heavy oil sewage deep aeration treatment system

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