JP3672117B2 - Organic wastewater treatment method and apparatus - Google Patents

Organic wastewater treatment method and apparatus Download PDF

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JP3672117B2
JP3672117B2 JP26025395A JP26025395A JP3672117B2 JP 3672117 B2 JP3672117 B2 JP 3672117B2 JP 26025395 A JP26025395 A JP 26025395A JP 26025395 A JP26025395 A JP 26025395A JP 3672117 B2 JP3672117 B2 JP 3672117B2
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sludge
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biological treatment
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separation
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JPH0999292A (en
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克之 片岡
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Ebara Corp
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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
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Description

【０００１】
【発明の属する技術分野】
本発明は、下水等の有機性汚水を生物処理する新技術に関するものであり、特に汚水の生物処理にともなう余剰汚泥発生量を、処理水の水質を悪化させることなく、著しく削減できる新技術に関するものである。
【０００２】
【従来の技術】
従来から、活性汚泥法などの生物処理にともなって発生する余剰汚泥量の削減法として特開平６−２０６０８８号公報が公知である。この技術は、有機性汚水をオゾン酸化して可溶化した後、汚水処理工程の曝気槽に返送し、好気性微生物により生物学的にＣＯ2 、Ｈ2 Ｏに分解することによって汚泥減量化を行うものである。
【０００３】
しかし、有機性汚水をオゾン酸化して可溶化した後、汚水処理工程の曝気槽に返送する前記従来技術を本発明者が追試した結果、次のような今まで知られていなかった大きな欠点があるこが判明した。すなわち、
▲１▼ オゾン酸化する汚泥量を増加し、汚泥減容化率を高めるほど、無機リン、ＣＯＤ濃度が悪化する。この原因を調べたところ汚泥をオゾン酸化すると汚泥からリンおよび難生物分解性のＣＯＤが溶出するためであることが判明した。
▲２▼ 汚泥減容化率を高めるほど、汚泥から窒素成分の溶出量が増加し、処理水の窒素濃度を悪化させる。
つまり前記従来技術は、汚泥減容化効果はある反面、処理水質の悪化を引き起こし汚水処理の本来の目的である汚水の浄化を満足させることができない技術であることが判明した。
【０００４】
【発明が解決しようとする課題】
本発明は、処理水質の悪化を引き起こすことなく、余剰汚泥の発生量を大幅に削減可能にする新技術を提供することを課題とする。
【０００５】
【課題を解決するための手段】
本発明の上記課題は、下記の手段により解決した。
（１）有機性汚水を生物処理する工程において、生物処理流出液を固液分離し、固液分離からの分離汚泥の一部を生物処理工程に返送し、前記分離汚泥の他部および／または前記生物処理工程からの引抜汚泥からなる移送汚泥をオゾン酸化した後、オゾン酸化した可溶化汚泥を固液分離し、分離された濃縮可溶化汚泥を前記生物処理工程に返送し、分離された分離液に無機凝集剤を添加し、凝集分離してリン、ＣＯＤを除去し、凝集分離で生じた凝集分離液を前記生物処理工程に返送することを特徴とする有機性汚水の処理方法。
（２）前記生物処理工程が活性汚泥法による処理工程であることを特徴とする前記（１）に記載の有機性汚水の処理方法。
【０００６】
（３）前記生物処理する工程が硝化脱窒素法による処理工程であり、前記オゾン酸化後の凝集分離液を前記工程の嫌気的脱窒素槽に返送することを特徴とする前記（１）に記載の有機性汚水の処理方法。
（４）前記生物処理する工程が生物脱リン法による処理工程であり、前記オゾン酸化後の凝集分離液を前記工程の嫌気的リン吐き出し槽に返送することを特徴とする請求項１に記載の有機性汚水の処理方法。
（５）有機性汚水を生物処理する装置において、生物処理装置からの流出液を固液分離する固液分離装置、固液分離装置からの分離汚泥の一部を生物処理装置に返送する配管、前記分離汚泥の他部および／または前記生物処理装置からの引抜汚泥からなる移送汚泥をオゾン酸化するオゾン酸化装置、オゾン酸化装置からの可溶化汚泥を固液分離する固液分離装置、固液分離装置からの濃縮可溶化汚泥を前記生物処理装置に返送する配管、固液分離装置からの分離液に無機凝集剤を添加し、凝集分離してリン、ＣＯＤを除去する凝集分離装置、凝集分離装置からの凝集分離液を前記生物処理装置に返送する配管を有することを特徴とする有機性汚水の処理装置。
【０００７】
【発明の実施の形態】
前記（１）に記載の本発明の有機性汚水の生物処理工程の内標準的な活性汚泥法の工程のフローを図１に示し、以下に図１を用いて本発明を説明する。なお前記生物処理工程としては、活性汚泥法の他に生物学的脱窒素法や生物脱リン法などが採用できる。
【０００８】
図１において、生物処理工程が活性汚泥法による処理工程であり、前記活性汚泥処理が、例えば曝気槽１で行う場合において、曝気槽１に下水など原水２を供給する。曝気槽１において生物処理を行い、曝気槽１から流出するスラリ状汚泥３（以下単にスラリとよぶ。）を沈澱槽５に導き沈澱分離する。
本発明においては、先ず活性汚泥法の常法に従って、沈澱汚泥６の大部分は返送汚泥７として曝気槽１に返送し、沈澱汚泥の残部８および曝気槽１から引き抜いた引抜汚泥９を共に移送汚泥１０としてオゾン酸化槽１１に送り移送汚泥１０をオゾン酸化し、可溶化する。可溶化された汚泥を可溶化汚泥１２という。
この時、曝気槽１内に常に所定濃度のＭＬＳＳが維持されているように返送汚泥７の量を制御することが生物処理を最も効率よいものとする上、次工程のオゾン酸化処理の負荷を最も少なくするのに役立つ。
【０００９】
移送汚泥１０はをオゾン酸化されることにより、汚泥中の生物細胞はコロイド化、可溶化され、生物分解性有機物（ＢＯＤ）、難生物分解性物（ＣＯＤ）、リン、窒素を溶出する。オゾンの添加量は、汚泥ＳＳ重量あたり１０％〜２０％が好適である。オゾン量が少なすぎると汚泥可溶化が充分に進まず、また過剰であるとオゾンが無駄になりコスト高になる。なお、生物細胞のオゾン酸化反応はｐＨ１０〜１１のアルカリ条件下で効果的にすすむことが認められた。
【００１０】
本発明において、オゾン酸化された可溶化汚泥１２は、沈澱や遠心分離などの公知の固液分離手段１３によって固液分離し、分離された分離液１６を凝集槽１５に移送し、凝集槽１５において鉄系凝集剤、アルミニウム系凝集剤、石灰などのリン、ＣＯＤを同時に凝集除去できる凝集剤４を添加してリン、ＣＯＤを凝集剤４と共に凝集沈澱させる。凝集沈澱した凝集汚泥は系外に取り出す。この時可溶性の有機物（ＢＯＤ）は凝集除去されない。凝集分離液１７には生物分解性有機物が含まれているので曝気槽１に返送する。リン、ＣＯＤの凝集反応は早いので、攪拌時間は１０分間程度で良い。また凝集フロックの沈澱時間は１時間程度で良い。
この方法では、固液分離され、濃縮された可溶化汚泥は、生物処理工程に返送して処理することができるので、可溶化汚泥１２を固液分離しない場合より余剰汚泥が少なくなり好ましい。
【００１１】
既に前記したように、オゾン酸化槽１１に供給される移送汚泥１０の量は、曝気槽１内に常に所定濃度範囲のＭＬＳＳが維持されているように返送汚泥７の量を制御された残りの汚泥（残部汚泥８）に引抜汚泥９を加えた量とされる。前記曝気槽１内に維持されるＭＬＳＳの濃度範囲は、有機性汚水１リットルあたり４０００〜５０００ｍｇが適当である。曝気槽内のＭＬＳＳの濃度範囲を前記の値に維持することは曝気槽内にＭＬＳＳ自動測定器を設置することで容易に行うことができる。
曝気槽１内のＭＬＳＳの濃度を常に所定濃度範囲に維持するこによって、余剰汚泥発生量を大きく減少させることができ、条件によってはほぼゼロにすることが可能である。従って、本発明においては系外に排出される固形物は少量の凝集スラッジのみとすることができる。
【００１２】
なお、生物処理工程としては、前記説明した活性汚泥法の他に生物学的硝化脱窒素法が採用できる。この生物学的硝化脱窒素法を用いた本発明の生物処理工程のうち可溶化汚泥を固液分離する好ましい態様について図２に示して説明する。
図２において、原水２は脱窒素槽２０に供給され、硝化槽２１を経てスラリ状汚泥は沈澱槽２２に移送され、沈澱槽２２で固液分離され、分離液２３（処理水）は系外に排出する。
濃縮汚泥の１部は返送汚泥２４として脱窒素槽２０に還流され、他の１部は移送汚泥２５としてオゾン酸化槽１１で可溶化され、可溶化汚泥２６は、沈澱や遠心分離などの公知の固液分離手段１２によって固液分離し、分離液２７は凝集槽１５において前記リン、ＣＯＤを同時に凝集除去できる凝集剤４を添加してリン、ＣＯＤを凝集剤４と共に凝集沈澱させる。分離液２７よりリン、ＣＯＤを凝集除去された凝集分離液１７は脱窒素槽２０に返送する。
この方法では、可溶化汚泥２６を固液分離して、濃縮した可溶化汚泥２８は生物処理工程に返送して処理することができる。
【００１３】
また生物処理工程としていまひとつ生物学的脱リン法が採用できる。この場合のうち可溶化汚泥を固液分離する好ましい態様について図３に示した。
生物脱リン法とは、汚水を嫌気槽、好気槽の順で流下させ、活性汚泥を好気槽の後に設けられた沈殿池にて分離し、分離汚泥を嫌気槽にリサイクルさせるこにより、嫌気槽において活性汚泥からリンを吐き出させた後、好気槽において吐き出した量以上のリンを活性汚泥細胞内に取り込みリンを除去する方法である。
図３では、好気槽３１からの流出スラリは沈澱槽３２で固液分離され、分離液３３（処理水）は系外に排出し、濃縮汚泥の１部は返送汚泥３４として嫌気槽３０に還流され、他の１部は移送汚泥３５としてオゾン酸化槽１１で可溶化され、可溶化汚泥３６は、沈澱や遠心分離などの公知の固液分離手段１２によって固液分離し、分離液３７に前記リン、ＣＯＤを同時に凝集除去できる凝集剤４を添加してリン、ＣＯＤを凝集剤４と共に凝集沈澱させる。分離液３７よりリン、ＣＯＤが除去された凝集分離液１７は嫌気槽３０に返送する。
この方法では、可溶化汚泥３６を固液分離して、濃縮した可溶化汚泥３８は生物処理工程に返送して処理することができる。
【００１４】
【実施例】
図１の工程に基づいて、下水を対象として、曝気槽を用いた有機性汚水の活性汚泥法による浄化処理を行った。
実施例１
処理に使用した下水の水質を第１表に示す。
第１表

Figure 0003672117
曝気槽の容積、下水の処理量、曝気槽のＭＬＳＳ量は第２表の通りである。
第２表
曝気槽容積 ： ６ リットル
曝気槽ＭＬＳＳ ： ３５００ ｍｇ／リットル
下水処理量 ： ２４ リットル／日
【００１５】
曝気槽における沈殿汚泥および沈殿槽において沈殿した汚泥の大部分は曝気槽に返送する。この返送量は、曝気槽に備えたＭＬＳＳ自動測定器により、曝気槽内のＭＬＳＳ量を管理しながら行った。その結果、オゾン酸化処理を行わず、曝気槽に返送する返送汚泥量は２０リットル／日であった。
一方オゾン酸化を行うための移送汚泥量は、本処理の場合１．５〜１．７ｇ・ｓｓ／日である。
オゾン酸化の条件を第３表に示す。
第３表
オゾン酸化槽容積 ： １リットル
オゾン酸化槽ｐＨ ： １０
オゾン添加量 ： １５％（流入ＳＳ当たり）
【００１６】
オゾン酸化した可溶化汚泥は沈澱分離し、沈澱した汚泥は曝気槽に返送し、分離した液は凝集分離槽で凝集剤を添加してリン、およびＣＯＤ成分を凝集沈澱させて系外に排出し、分離液は曝気槽に返送する。
凝集剤の添加条件を第４表に示す。
第４表
凝集剤（塩化第２鉄）添加量： ２０００〜３０００ ｍｇ／リットル
凝集ｐＨ ： ６
【００１７】
以上の条件で１年間処理を行った結果、処理水の水質は第５表の通りである。
第５表
Figure 0003672117
となり、極めて良好な水質の処理水が得られ、リン、ＣＯＤの悪化は認められなかった。また、余剰生物汚泥発生量は下水１ｍ3 あたり２．８〜４．８ｇ・ｓｓと極めてすくなかった。なお、標準活性汚泥法における余剰生物汚泥発生量は下水１ｍ3 あたり４０〜５０ｇ・ｓｓである。
【００１８】
比較例１
図１に示した汚水の処理工程において、オゾン酸化後の固液分離および凝集分離工程を除去した以外は表２〜表３に示した条件と同一条件で比較試験を行った。その結果、処理水の水質は第５表の通りであり、本発明の実施例の処理水の水質と比較してＣＯＤの値が３２ｍｇ／リットルと悪化した。
第５表
Figure 0003672117
【００１９】
【発明の効果】
本発明により下水など有機性汚水を対象とし、活性汚泥法、硝化脱窒素法あるいは生物脱リン法を適用して生物処理するにあたり、好ましくは、
▲１▼活性汚泥法では曝気槽から流出するスラリ状汚泥を固液分離し、濃縮汚泥をオゾン酸化可溶化処理し、可溶化汚泥を固液分離し、濃縮汚泥は曝気槽に返送し、その分離液に凝集剤を添加してリン、ＣＯＤを除去する。
▲２▼硝化脱窒素法では脱窒素槽と硝化槽を通ったスラリ状汚泥を固液分離し、濃縮汚泥をオゾン酸化可溶化処理し、可溶化汚泥を固液分離し、濃縮汚泥は脱窒素槽に返送し、その分離液に凝集剤を添加してリン、ＣＯＤを除去する。
▲３▼生物脱リン法では脱リンするための嫌気槽、つづいて好気槽を通ったスラリ状汚泥を固液分離し、濃縮汚泥をオゾン酸化可溶化処理し、可溶化汚泥を固液分離し、濃縮汚泥は嫌気槽にに返送し、その分離液に凝集剤を添加してリン、ＣＯＤを除去する。
前記▲１▼〜▲３▼の生物処理する方法を行った結果、
（１）処理工程から余剰汚泥が殆ど発生しない。
（２）処理水の水質（特にリン、ＣＯＤ）の悪化がない。
という優れた効果が得られる。
また、前記▲１▼〜▲３▼の生物処理する方法において、可溶化汚泥を固液分離することなく、それに凝集剤を添加して凝集沈殿させて、可溶化汚泥からリン、ＣＯＤを除去し、凝集分離液を処理系に返送する方法によって余剰汚泥を少なくでき、かつ処理水の水質の悪化させずに生物処理することができる。
【図面の簡単な説明】
【図１】活性汚泥法による本発明の有機性汚水の生物処理のフローの１例を示す説明図である。
【図２】硝化脱窒素法による本発明の有機性汚水の生物処理のフローの１例を示す説明図である。
【図３】生物脱リン法による本発明の有機性汚水の生物処理のフローの１例を示す説明図である。
【符号の説明】
１ 曝気槽
２ 原水
３ スラリー
４ 凝集剤
５ 沈殿槽
６ 沈殿汚泥
７ 返送汚泥
８ 汚泥残部
９ 引抜汚泥
１０ 移送汚泥
１１ オゾン酸化槽
１２ 可溶化汚泥
１３ 固液分離手段
１４ 凝集汚泥
１５ 凝集槽
１６ 分離液
１７ 凝集分離液
２０ 脱窒素槽
２１ 硝化槽
２２ 沈澱槽
２３ 分離液（処理水）
２４ 返送汚泥
２５ 移送汚泥
２６ 可溶化汚泥
２７ 分離液
２８ 濃縮可溶化汚泥
３０ 嫌気槽
３１ 好気槽
３２ 沈澱槽
３３ 分離液（処理水）
３４ 返送汚泥
３５ 移送汚泥
３６ 可溶化汚泥
３７ 分離液
３８ 濃縮可溶化汚泥[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a new technology for biologically treating organic sewage such as sewage, and particularly to a new technology that can significantly reduce the amount of excess sludge generated by biological treatment of sewage without deteriorating the quality of the treated water. Is.
[0002]
[Prior art]
Conventionally, Japanese Patent Laid-Open No. 6-206088 is known as a method for reducing the amount of surplus sludge generated with biological treatment such as the activated sludge method. In this technology, organic sewage is solubilized by ozone oxidation, then returned to the aeration tank in the sewage treatment process, and biologically decomposed into CO 2 and H 2 O by aerobic microorganisms to reduce sludge. Is what you do.
[0003]
However, as a result of the inventor's additional trial of the above prior art for returning the organic sewage to the aeration tank in the sewage treatment step after solubilizing the organic sewage with ozone, the following major drawbacks have not been known so far: It turns out that there is. That is,
(1) The concentration of inorganic phosphorus and COD worsens as the amount of sludge to be oxidized by ozone increases and the volume reduction rate of sludge increases. As a result of investigating the cause, it was found that phosphorus and hardly biodegradable COD were eluted from the sludge when the sludge was oxidized with ozone.
(2) As the sludge volume reduction rate increases, the amount of nitrogen components eluted from the sludge increases, and the nitrogen concentration of the treated water deteriorates.
In other words, it has been found that the above-mentioned prior art has a sludge volume reduction effect, but does not satisfy the purification of sewage, which is the original purpose of sewage treatment, because the quality of the treated water is deteriorated.
[0004]
[Problems to be solved by the invention]
This invention makes it a subject to provide the new technique which makes it possible to reduce significantly the generation amount of an excess sludge, without causing the deterioration of treated water quality.
[0005]
[Means for Solving the Problems]
The above-described problems of the present invention have been solved by the following means.
(1) In the step of biologically treating organic sewage, the biological treatment effluent is subjected to solid-liquid separation, a part of the separated sludge from the solid-liquid separation is returned to the biological treatment step, and the other part of the separated sludge and / or After the transfer sludge consisting of the extracted sludge from the biological treatment process is ozone-oxidized, the ozone-oxidized solubilized sludge is separated into solid and liquid, and the separated concentrated solubilized sludge is returned to the biological treatment process and separated. An organic sewage treatment method characterized by adding an inorganic flocculant to a liquid , coagulating and separating to remove phosphorus and COD, and returning the coagulated separation liquid produced by the coagulation separation to the biological treatment step.
(2) The method for treating organic sewage according to (1) above, wherein the biological treatment step is a treatment step by an activated sludge method.
[0006]
(3) In the case of processing steps biological treatment for step by nitrification denitrification method, according to (1), characterized in that to return the coagulation and separation liquid after the ozone oxidation in anaerobic denitrification tank of step Treatment method of organic wastewater.
(4) In the case of processing steps biological treatment to steps by an organism dephosphorization method, according to claim 1, characterized in that to return the coagulation and separation liquid after the ozone oxidation in anaerobic phosphorus discharging vessel of step Organic sewage treatment method.
(5) In a device for biologically treating organic sewage, a solid-liquid separation device for solid-liquid separation of the effluent from the biological treatment device, a pipe for returning a part of the separated sludge from the solid-liquid separation device to the biological treatment device, Ozone oxidizer for ozone-oxidizing the other part of the separated sludge and / or transported sludge composed of drawn sludge from the biological treatment device, solid-liquid separator for solid-liquid separation of solubilized sludge from the ozone oxidizer, solid-liquid separation A pipe for returning the concentrated solubilized sludge from the apparatus to the biological treatment apparatus, an aggregating agent added to the separation liquid from the solid-liquid separation apparatus, and aggregating and separating to remove phosphorus and COD; An apparatus for treating organic sewage, comprising a pipe for returning the flocculated and separated liquid from the biological treatment apparatus.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The flow of the standard activated sludge process in the biological treatment process of organic sewage according to the present invention described in (1) is shown in FIG. 1, and the present invention will be described below with reference to FIG. In addition to the activated sludge method, a biological denitrification method or a biological dephosphorization method can be employed as the biological treatment step.
[0008]
In FIG. 1, when the biological treatment process is a treatment process by an activated sludge method and the activated sludge treatment is performed in, for example, the aeration tank 1, raw water 2 such as sewage is supplied to the aeration tank 1. Biological treatment is performed in the aeration tank 1, and slurry sludge 3 (hereinafter simply referred to as “slurry”) flowing out from the aeration tank 1 is guided to the precipitation tank 5 for precipitation separation.
In the present invention, first, most of the precipitated sludge 6 is returned to the aeration tank 1 as a return sludge 7 in accordance with a conventional method of the activated sludge method, and the remaining portion 8 of the precipitated sludge and the drawn sludge 9 extracted from the aeration tank 1 are transferred together. The sludge 10 is sent to the ozone oxidation tank 11 and the transported sludge 10 is oxidized with ozone and solubilized. The solubilized sludge is referred to as solubilized sludge 12.
At this time, controlling the amount of the returned sludge 7 so that the predetermined concentration of MLSS is always maintained in the aeration tank 1 makes the biological treatment most efficient, and the load of ozone oxidation treatment in the next step is reduced. Helps to minimize.
[0009]
As the transported sludge 10 is oxidized with ozone, the biological cells in the sludge are colloided and solubilized to elute biodegradable organic substances (BOD), hardly biodegradable substances (COD), phosphorus and nitrogen. The amount of ozone added is preferably 10% to 20% per sludge SS weight. If the amount of ozone is too small, solubilization of sludge will not proceed sufficiently, and if it is excessive, ozone will be wasted and cost will increase. In addition, it was recognized that the ozone oxidation reaction of biological cells can proceed effectively under alkaline conditions of pH 10-11.
[0010]
In the present invention, the ozone-oxidized solubilized sludge 12 is subjected to solid-liquid separation by a known solid-liquid separation means 13 such as precipitation or centrifugation, and the separated separation liquid 16 is transferred to a flocculation tank 15. In the above, an iron-based flocculant, an aluminum-based flocculant, phosphorus such as lime, and a flocculant 4 that can coagulate and remove COD are added to coagulate and precipitate phosphorus and COD together with the flocculant 4. The coagulated sludge that has been coagulated and precipitated is taken out of the system. At this time, soluble organic matter (BOD) is not agglomerated and removed. Since the coagulation / separation liquid 17 contains a biodegradable organic substance, it is returned to the aeration tank 1. Since the aggregation reaction of phosphorus and COD is fast, the stirring time may be about 10 minutes. The precipitation time of the floc floc may be about 1 hour.
This method is preferable because the solubilized sludge separated and concentrated by solid-liquid separation can be returned to the biological treatment process for processing, and therefore , excess sludge is reduced as compared with the case where the solubilized sludge 12 is not solid-liquid separated .
[0011]
As described above, the amount of the transfer sludge 10 supplied to the ozone oxidation tank 11 is the remaining amount of the return sludge 7 controlled so that the MLSS in the predetermined concentration range is always maintained in the aeration tank 1. The amount of the extracted sludge 9 is added to the sludge (remaining sludge 8). The concentration range of MLSS maintained in the aeration tank 1 is suitably 4000 to 5000 mg per liter of organic waste water. Maintaining the MLSS concentration range in the aeration tank at the above value can be easily performed by installing an MLSS automatic measuring instrument in the aeration tank.
By always maintaining the concentration of MLSS in the aeration tank 1 within a predetermined concentration range, it is possible to greatly reduce the amount of excess sludge generation, and it is possible to make it almost zero depending on the conditions. Therefore, in the present invention, the solid matter discharged out of the system can be only a small amount of agglomerated sludge.
[0012]
In addition to the activated sludge method described above, a biological nitrification denitrification method can be employed as the biological treatment process. A preferred embodiment of solid-liquid separation of solubilized sludge in the biological treatment process of the present invention using this biological nitrification denitrification method is shown in FIG.
In FIG. 2, raw water 2 is supplied to a denitrification tank 20, slurry sludge is transferred to a precipitation tank 22 through a nitrification tank 21, and solid-liquid separation is performed in the precipitation tank 22, and a separation liquid 23 (treated water) is outside the system. To discharge.
One part of the concentrated sludge is returned to the denitrification tank 20 as a return sludge 24, the other part is solubilized in the ozone oxidation tank 11 as a transfer sludge 25, and the solubilized sludge 26 is a known one such as sedimentation or centrifugation. Solid-liquid separation is performed by the solid-liquid separation means 12, and the separation liquid 27 is coagulated and precipitated with the coagulant 4 by adding the coagulant 4 that can coagulate and remove the phosphorus and COD in the coagulation tank 15. Aggregated and separated liquid 17 from which phosphorus and COD have been aggregated and removed from separated liquid 27 is returned to denitrification tank 20.
In this method, the solubilized sludge 28 is separated into solid and liquid, and the concentrated solubilized sludge 28 can be returned to the biological treatment process for processing.
[0013]
In addition, another biological dephosphorization method can be adopted as a biological treatment process. FIG. 3 shows a preferred embodiment for solid-liquid separation of the solubilized sludge in this case.
The biological dephosphorization method is to drain sewage in the order of an anaerobic tank and an aerobic tank, separate activated sludge in a sedimentation pond provided after the aerobic tank, and recycle the separated sludge to the anaerobic tank. This is a method of removing phosphorus from activated sludge in an anaerobic tank, and then taking in more phosphorus than the amount discharged in the aerobic tank into activated sludge cells.
In FIG. 3, the outflow slurry from the aerobic tank 31 is solid-liquid separated in the precipitation tank 32, the separation liquid 33 (treated water) is discharged out of the system, and a part of the concentrated sludge is returned to the anaerobic tank 30 as return sludge 34. The other part is solubilized in the ozone oxidation tank 11 as a transfer sludge 35, and the solubilized sludge 36 is solid-liquid separated by a well-known solid-liquid separation means 12 such as precipitation or centrifugal separation into a separated liquid 37. The aggregating agent 4 capable of coagulating and removing phosphorus and COD at the same time is added to agglomerate and precipitate phosphorus and COD together with the aggregating agent 4. The agglomerated separation liquid 17 from which phosphorus and COD have been removed from the separation liquid 37 is returned to the anaerobic tank 30.
In this method, the solubilized sludge 36 is separated into solid and liquid, and the concentrated solubilized sludge 38 can be returned to the biological treatment process for processing.
[0014]
【Example】
Based on the process of FIG. 1, the purification process by the activated sludge method of the organic sewage using the aeration tank was performed for sewage.
Example 1
Table 1 shows the quality of sewage used in the treatment.
Table 1
Figure 0003672117
Table 2 shows the volume of the aeration tank, the treatment amount of sewage, and the MLSS amount of the aeration tank.
Table 2 Aeration tank volume: 6 liters Aeration tank MLSS: 3500 mg / liter Sewage treatment amount: 24 liters / day
Most of the sludge settled in the aeration tank and sludge settled in the settling tank is returned to the aeration tank. This return amount was performed while managing the MLSS amount in the aeration tank by an MLSS automatic measuring device provided in the aeration tank. As a result, the amount of sludge returned to the aeration tank without performing the ozone oxidation treatment was 20 liters / day.
On the other hand, the amount of transferred sludge for performing ozone oxidation is 1.5 to 1.7 g · ss / day in the case of this treatment.
The conditions for ozone oxidation are shown in Table 3.
Table 3. Volume of ozone oxidation tank: 1 liter ozone oxidation tank pH: 10
Ozone addition amount: 15% (per inflow SS)
[0016]
Ozone-oxidized solubilized sludge is separated and precipitated, and the precipitated sludge is returned to the aeration tank. The separated liquid is added to the flocculant separation tank, and the phosphorus and COD components are agglomerated and precipitated and discharged out of the system. The separated liquid is returned to the aeration tank.
Table 4 shows the conditions for adding the flocculant.
Table 4: Coagulant (ferric chloride) addition amount: 2000 to 3000 mg / liter aggregation pH: 6
[0017]
As a result of the treatment for one year under the above conditions, the quality of the treated water is as shown in Table 5.
Table 5
Figure 0003672117
Thus, treated water with extremely good water quality was obtained, and no deterioration of phosphorus and COD was observed. Moreover, the surplus biological sludge generation amount was extremely low at 2.8 to 4.8 g · ss per 1 m 3 of sewage. In addition, the surplus biological sludge generation amount in the standard activated sludge method is 40 to 50 g · ss per 1 m 3 of sewage.
[0018]
Comparative Example 1
In the wastewater treatment process shown in FIG. 1, a comparative test was performed under the same conditions as those shown in Tables 2 to 3 except that the solid-liquid separation and the aggregation separation process after ozone oxidation were removed. As a result, the quality of the treated water is as shown in Table 5. Compared with the quality of the treated water of the example of the present invention, the COD value was deteriorated to 32 mg / liter.
Table 5
Figure 0003672117
[0019]
【The invention's effect】
In subjecting organic sewage such as sewage according to the present invention to biological treatment by applying activated sludge method, nitrification denitrogenation method or biological dephosphorization method, preferably,
(1) In the activated sludge method, the sludge sludge flowing out from the aeration tank is solid-liquid separated, the concentrated sludge is solubilized by ozone oxidation, the solubilized sludge is solid-liquid separated, and the concentrated sludge is returned to the aeration tank. A flocculant is added to the separation liquid to remove phosphorus and COD.
(2) In the nitrification and denitrification method, slurry sludge that has passed through the denitrification tank and nitrification tank is solid-liquid separated, the concentrated sludge is solubilized by ozone oxidation, the solubilized sludge is separated into solid and liquid, and the concentrated sludge is denitrogenated. It returns to a tank and a flocculant is added to the separated liquid to remove phosphorus and COD.
(3) In the biological dephosphorization method, the anaerobic tank for dephosphorization, followed by the slurry sludge that passed through the aerobic tank is solid-liquid separated, the concentrated sludge is solubilized by ozone oxidation, and the solubilized sludge is solid-liquid separated. The concentrated sludge is returned to the anaerobic tank, and a flocculant is added to the separated liquid to remove phosphorus and COD.
As a result of performing the biological treatment method of (1) to (3) above,
(1) Surplus sludge is hardly generated from the treatment process.
(2) The quality of treated water (especially phosphorus, COD) is not deteriorated.
An excellent effect is obtained.
In addition, in the above biological treatment methods (1) to (3), the solubilized sludge is not subjected to solid-liquid separation, but a coagulant is added and coagulated to remove phosphorus and COD from the solubilized sludge. By the method of returning the flocculated separation liquid to the treatment system, excess sludge can be reduced, and biological treatment can be performed without deteriorating the quality of the treated water.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an example of a biological treatment flow of organic sewage of the present invention by an activated sludge method.
FIG. 2 is an explanatory diagram showing an example of a biological treatment flow of organic wastewater according to the present invention by a nitrification denitrification method.
FIG. 3 is an explanatory diagram showing an example of a biological treatment flow of the organic wastewater of the present invention by a biological dephosphorization method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Aeration tank 2 Raw water 3 Slurry 4 Coagulant 5 Precipitation tank 6 Precipitation sludge 7 Return sludge 8 Sludge remainder 9 Extraction sludge 10 Transfer sludge 11 Ozone oxidation tank 12 Solubilization sludge 13 Solid-liquid separation means 14 Aggregation sludge 15 Aggregation tank 16 Separation liquid 17 Aggregation separation liquid 20 Denitrification tank 21 Nitrification tank 22 Precipitation tank 23 Separation liquid (treated water)
24 Return sludge 25 Transfer sludge 26 Solubilized sludge 27 Separation liquid 28 Concentrated solubilized sludge 30 Anaerobic tank 31 Aerobic tank 32 Precipitation tank 33 Separation liquid (treated water)
34 Return sludge 35 Transfer sludge 36 Solubilized sludge 37 Separation liquid 38 Concentrated solubilized sludge

Claims (5)

有機性汚水を生物処理する工程において、生物処理流出液を固液分離し、固液分離からの分離汚泥の一部を生物処理工程に返送し、前記分離汚泥の他部および／または前記生物処理工程からの引抜汚泥からなる移送汚泥をオゾン酸化した後、オゾン酸化した可溶化汚泥を固液分離し、分離された濃縮可溶化汚泥を前記生物処理工程に返送し、分離された分離液に無機凝集剤を添加し、凝集分離してリン、ＣＯＤを除去し、凝集分離で生じた凝集分離液を前記生物処理工程に返送することを特徴とする有機性汚水の処理方法。In the process of biological treatment of organic sewage, the biological treatment effluent is subjected to solid-liquid separation, a part of the separated sludge from the solid-liquid separation is returned to the biological treatment process, the other part of the separated sludge and / or the biological treatment. After the transfer sludge consisting of the extracted sludge from the process is ozone-oxidized, the ozone-oxidized solubilized sludge is solid-liquid separated, the separated concentrated solubilized sludge is returned to the biological treatment process, and the separated separated liquid is inorganic. A method for treating organic wastewater, comprising adding a flocculant, separating and removing phosphorus and COD by aggregating, and returning the agglomerated separation liquid produced by the aggregating separation to the biological treatment step. 前記生物処理工程が活性汚泥法による処理工程であることを特徴とする請求項１に記載の有機性汚水の処理方法。 The method for treating organic sewage according to claim 1, wherein the biological treatment step is a treatment step by an activated sludge method. 前記生物処理する工程が硝化脱窒素法による処理工程であり、前記オゾン酸化後の凝集分離液を前記工程の嫌気的脱窒素槽に返送することを特徴とする請求項１に記載の有機性汚水の処理方法。The organic sewage according to claim 1, wherein the biological treatment step is a treatment step by a nitrification denitrification method, and the aggregated separation liquid after the ozone oxidation is returned to the anaerobic denitrification tank of the step. Processing method. 前記生物処理する工程が生物脱リン法による処理工程であり、前記オゾン酸化後の凝集分離液を前記工程の嫌気的リン吐き出し槽に返送することを特徴とする請求項１に記載の有機性汚水の処理方法。The organic sewage according to claim 1, wherein the biological treatment step is a biological dephosphorization treatment step, and the aggregated separation liquid after the ozone oxidation is returned to the anaerobic phosphorus discharge tank of the step. Processing method. 有機性汚水を生物処理する装置において、生物処理装置からの流出液を固液分離する固液分離装置、固液分離装置からの分離汚泥の一部を生物処理装置に返送する配管、前記分離汚泥の他部および／または前記生物処理装置からの引抜汚泥からなる移送汚泥をオゾン酸化するオゾン酸化装置、オゾン酸化装置からの可溶化汚泥を固液分離する固液分離装置、固液分離装置からの濃縮可溶化汚泥を前記生物処理装置に返送する配管、固液分離装置からの分離液に無機凝集剤を添加し、凝集分離してリン、ＣＯＤを除去する凝集分離装置、凝集分離装置からの凝集分離液を前記生物処理装置に返送する配管を有することを特徴とする有機性汚水の処理装置。In an apparatus for biological treatment of organic sewage, a solid-liquid separation apparatus for solid-liquid separation of the effluent from the biological treatment apparatus, a pipe for returning a part of the separated sludge from the solid-liquid separation apparatus to the biological treatment apparatus, and the separated sludge From the other part and / or the ozone oxidizer that oxidizes the transfer sludge composed of the extracted sludge from the biological treatment apparatus, the solid-liquid separator that separates the solubilized sludge from the ozone oxidizer into solid-liquid, and the solid-liquid separator A pipe for returning the concentrated solubilized sludge to the biological treatment apparatus, a flocculant separation apparatus for removing phosphorus and COD by adding an inorganic flocculant to the separated liquid from the solid-liquid separator, and agglomerating from the flocculent separator An apparatus for treating organic sewage, comprising a pipe for returning a separation liquid to the biological treatment apparatus.
JP26025395A 1995-10-06 1995-10-06 Organic wastewater treatment method and apparatus Expired - Fee Related JP3672117B2 (en)

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