JP3606449B2 - Filter body washing method and apparatus - Google Patents
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- JP3606449B2 JP3606449B2 JP2000336285A JP2000336285A JP3606449B2 JP 3606449 B2 JP3606449 B2 JP 3606449B2 JP 2000336285 A JP2000336285 A JP 2000336285A JP 2000336285 A JP2000336285 A JP 2000336285A JP 3606449 B2 JP3606449 B2 JP 3606449B2
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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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- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Description
【０００１】
【発明の属する技術分野】
本発明は、汚水処理に関するもので、特に活性汚泥の固液分離や余剰汚泥の濃縮等に使用する通水性ろ過体の洗浄に関するものであり、有機性工業廃水や生活排水等の処理に用いることができる通水性ろ過体の洗浄方法及び装置に関する。
【０００２】
【従来の技術】
従来、活性汚泥による水処理では、処理水を得るためには活性汚泥の固液分離を行わなければならない。通常では、活性汚泥を沈澱池に導入させ、重力沈降によって、汚泥を沈降させ、上澄液を処理水として沈澱池から流出させる方法が用いられる。この場合、活性汚泥を沈降させるため十分な沈降ができるような大きな沈降面積及び長い滞留時間を有する沈澱池が必要であり、処理装置の大型化と設置容積の増大要因となっている。また、活性汚泥がバルキング等、沈降性の悪化した場合、沈澱池より汚泥が流出し、処理水の悪化を招く。
【０００３】
近年、沈澱池に代わって膜分離による活性汚泥の固液分離を行う手法も用いられている。この場合、固液分離用膜として、一般的に精密ろ過膜や限外ろ過膜が用いられる。
その際、ろ過分離手段としてポンプによる吸引や加圧が必要であり、通常数十ｋＰａ〜数百ｋＰａの圧力で行うため、ポンプによる動力が大きく、ランニングコストの増大となっている。また、膜分離でＳＳの全くない清澄な処理水が得られる一方、透過Ｆｌｕｘが低く、膜汚染を防止するため、定期的に薬洗する必要がある。
【０００４】
最近、沈澱池に代わる活性汚泥の固液分離法として、曝気槽に不織布等の通気性シートからなるろ過体を浸漬させ、低い水頭圧でろ過水を得る方法が知られている（特開平５−１８５０７８）。この場合、ろ過体表面に形成された汚泥のダイナミックろ過による分離で清澄なろ過水が得られる。また、ろ過Ｆｌｕｘ低下時のろ過体の洗浄方法としては、ろ過体より下に設置した散気管より曝気すれば、ろ過体表面に形成された汚泥のダイナミックろ過層を容易に剥離し、安定したろ過Ｆｌｕｘが得られるとしている。
【０００５】
【発明が解決しようとする課題】
しかし、ろ過体を曝気槽に浸漬したまま、空洗のみによる洗浄では、ろ過Ｆｌｕｘが徐々に低下することが認められた。処理日数の増加にともない、空洗直後のろ過Ｆｌｕｘが初期値に比べ徐々に低下した。また、初期値に対する割合を示す回復率も同様に低下し、空洗回数の増加にともない、その低下が大きくなる。ろ過体を曝気槽に浸漬した場合、ろ過体表面に形成された汚泥のダイナミックろ過層が空洗によって完全に剥離されなかった時、微細な汚泥フロックがろ過体表面に付着し、長期ろ過にともない、付着汚泥の微細化でろ過体表面の閉塞を引き起こす。また、付着汚泥に有機物の吸着や分解等により汚泥性状が悪化し、ろ過体表面に生物膜の形成でろ過Ｆｌｕｘの低下を招くことがある。この結果、空洗のみの洗浄効果が得られず、経過時間とともにろ過Ｆｌｕｘの低下が大きくなり、安定した処理を得ることが困難となる。
【０００６】
本発明は、このような従来の課題に鑑みてなされたものであり、通水性ろ過体の表面に対し水洗を行い、初期値とほぼ同様なろ過Ｆｌｕｘを、長期間にわたって安定して得られ、しかも、安定した処理水量、水質も得ることができる生物処理汚水の固液分離装置のろ過体の洗浄方法及び装置を得ることを課題とする。
【０００７】
【課題を解決するための手段】
本発明者等は、前記の課題により、処理時間の経過と関係なく、常にろ過体の表面に均一なダイナミックろ過層を形成する方法について種々研究した。
そして、ろ過体表面に対し水洗ノズルからろ過水を噴射すれば、通常の空洗では完全に剥離できなかったろ過体表面の微細なフロックを容易に洗い落とすことが可能になることが確認できた。
また、洗浄用の水洗ノズルがろ過体表面に対し、投射角３０〜１２０度で洗浄水を噴射することにより、ろ過体表面に付着した微細な汚泥を瞬時に洗い落とすことができることも確認できた。
さらに、洗浄後のろ過体に再び混合汚泥を供給し、ダイナミックろ過層によるろ過を行えば、初期値とほぼ同様なろ過Ｆｌｕｘが得られることを見出した。
【０００８】
本発明は、このような知見に基づいてなされたものであり、次の手段により前記の課題を解決した。
（１）原水を生物反応槽に流入し、好気的に活性汚泥による処理を行った後、生物反応槽から活性汚泥混合液を通水性ろ過体を設置したろ過分離槽に供給し、該ろ過分離槽でろ過体表面に汚泥のダイナミックろ過層を形成させてろ過を行ってろ過水を得、ろ過後の活性汚泥混合液を生物反応槽に返送する固液分離法において、ろ過体洗浄時に、ろ過分離槽内の活性汚泥混合液を生物反応槽に完全に返送した時点で、ろ過体より上に設置された水洗ユニットをろ過体に面する液の流路に降下させて、ろ過体表面に対し水洗することを特徴とするろ過体の洗浄方法。
（２）水洗ユニットが噴水ノズルより構成され、ろ過分離槽に降下し、ろ過体に面する液の流路を上下移動させながら、或いは停止して、ろ過体表面に対し、投射角３０〜１２０度でノズルからろ過水を噴射することを特徴とする前記（１）記載のろ過体の洗浄方法。
【０００９】
（３）通水性ろ過体を用い、ろ過体表面に汚泥のダイナミックろ過層を形成してろ過水を得る生物処理汚水の固液分離装置において、汚水が流入する生物反応槽と別個に設けられたろ過分離槽内に浸漬されたダイナミックろ過層を形成した通水性ろ過体と、このろ過体より下に配置されたろ過体浸漬中の空洗用の空洗散気管と、ろ過分離槽内の活性汚泥混合液の生物反応槽への完全返送時に、ろ過体に面する液の流路に下降させてろ過体表面の水洗を行うためのろ過体より上に設置された水洗ユニットを有することを特徴とするろ過体の洗浄装置。
（４）水洗ユニットが噴水ノズルより構成され、かつろ過分離槽内に降下し、ろ過体に面する液の流路を上下移動中に、或いは停止中に、ろ過体表面に対し、投射角３０〜１２０度のノズルからろ過水を噴射するように構成されることを特徴とする前記（３）記載のろ過体の洗浄装置。
【００１０】
【発明の実施の形態】
本発明によれば、通水性ろ過体を用い、ろ過体表面に汚泥のダイナミックろ過層を形成してろ過水を得る汚泥混合液の固液分離方法において、ろ過体を浸漬するろ過分離槽の上部に噴水ノズルを有する水洗ユニットを設置し、定期的にろ過分離槽内の汚泥混合液を一旦全部生物反応槽へ返送した後、水洗ユニットをろ過分離槽内に降下させ、ろ過体に面する液の流路を移動させながら、或いは停止中に水洗ユニットの噴水ノズルから洗浄水をろ過体表面に噴射すれば、ろ過体表面に付着した微細な汚泥粒子を容易に落とすことができる。通常の空洗ではろ過体表面に微細な汚泥粒子が付着し、ろ過Ｆｌｕｘの回復が得られなかった場合、上記のような洗浄方法を行えば、ろ過Ｆｌｕｘが初期値に回復する。洗浄後にろ過分離槽に再び汚泥混合液を供給し、汚泥のダイナミックろ過層によるろ過を行えば、初期値とほぼ同様なろ過Ｆｌｕｘが得られる。その結果、長期間にわたって、安定したろ過Ｆｌｕｘが得られ、処理水量、水質とも安定して得られる。
【００１１】
水洗ユニットが水洗浄を行わない場合は、常時ろ過分離槽の上部に設置されており、水洗時はろ過分離槽内に降下させればよいことから、容易に自動化することができる。その際、処理状況や汚泥の性状に応じて水洗量や時間、頻度を変えることも可能である。
さらに、水洗ユニットに洗浄用のノズルが設置されており、ろ過体表面に対し、投射角３０〜１２０度で洗浄水を噴射することにより、ろ過体表面に付着した微細な汚泥粒子を瞬時に洗い落とすことができ、少ない洗浄水量で良好な洗浄効果が得られる。ここで、洗浄水としてはろ過水を用いることから、ろ過分離槽に新たな水を供給することなく、安定した洗浄を行うことができる。
【００１２】
通水性ろ過体としては、多孔性耐圧性支持体であれば、不織布、織布、金属網等のいずれを用いても同様な効果が得られる。また、ろ過体の形状としては、平面型、円筒型、中空型のいずれを用いることも可能であり、複数個を束ねてモジュールろ過体として用いることが可能である。
通水性ろ過体によりろ過分離できる対象汚泥としては、活性汚泥、凝集汚泥、初沈汚泥等の何れも可能である。また、ＳＳの高い排水、河川水等の固液分離手段として用いることも可能である。
水洗ユニットの形状は、ろ過体に面する液の流路に応じて、線形、円筒形等のいずれを用いても同様な効果が得られる。平面型のろ過体を用いた場合、ろ過体とろ過体間の液の流路を通過でき、ノズルを横一直線に接続した線形水洗ユニットを用いればよい。円筒状のろ過体を用いた場合、ろ過体間に侵入できる円筒状または球状の水洗ユニットを用いれば、水洗時での自動化及び簡易化が容易となる。
【００１３】
ろ過体へのろ過水による噴射洗浄は、水洗ユニットをろ過槽内で垂直降下及び上昇中に行えば、ろ過体表面のどの部分に対してもほぼ均一に洗浄することができ、付着した微細汚泥を効果的に除去することができる。また、場所によっては水洗ユニットを停止させ、そこで噴射洗浄を行わせるようにすることもでき、汚泥の付着量が多い場所に有効である。
水洗ユニットを、ろ過槽に設置されたろ過体間に垂直上昇または降下させる場合、噴射ノズルとろ過体との距離を一定とするのが好ましい。その方法としては、ろ過槽内部の両側に、水洗ユニットが垂直通過できる固定レールを予め設置しておけばよい。
水洗ユニットのノズルの噴射水量は、ろ過体表面積に対し、１〜５ｍ３ ／ｍ２ ／ｈ程度で、水洗圧力を１００〜２００ｋＰａとすれば、効果的な洗浄が得られる。洗浄時間は数分程度で十分である。
【００１４】
【実施例】
以下実施例により本発明を具体的に説明する。ただし本発明はこの実施例のみに限定されるものではない。
【００１５】
実施例１
図１は、団地下水に対する本発明による処理法の一例をフローシートで示すものである。
図１に示す如く、流入原水１が生物処理槽２に流入し、生物処理槽２において曝気ブロワ４より散気管３へ空気を供給することにより活性汚泥による好気処理を行う。活性汚泥混合液が、汚泥供給ポンプ５よりろ過分離槽６に供給される。ろ過分離槽６に流入した活性汚泥混合液は、通水性ろ過体９より水頭圧△Ｈでろ過され、ろ過水取水管１３を通じて流出し、処理水として処理水槽１６に流入する。なお、ろ過後の汚泥混合液は、循環汚泥１０として生物処理槽２に返送される。また、この実施例では、「生物反応槽」を「生物処理槽」という。
【００１６】
ろ過体９の洗浄法として、ろ過体浸漬中では、空洗によるろ過Ｆｌｕｘの安定化を行う。この時、空洗ブロワ７から一定時間毎に、ろ過体９下部の空洗散気管８に送気して行われる。水洗は定期的に行う。水洗時は、ろ過槽６内の混合液汚泥を、汚泥混合液供給バルブ５ａと移送バルブ５ｂの切換えで、汚泥混合液ポンプ５より一旦曝気槽へ返送した後、図２に示すように、水洗ユニット１７を移動リフト１９よりろ過分離槽６に降下しながら、ろ過体９の表面に水洗ノズル１５が達した時点で水洗ポンプ１１が起動し、処理水槽１６から処理水を圧送し、流量計１４で水量を制御して、水洗配管１２を通じて水洗ノズル１５よりろ過体９表面に噴射される。このように、水洗ノズル１５がろ過体９表面に対し、降下及び上昇を繰り返しながらろ過水が噴射される。
第１表に実施例１でのろ過分離槽の処理条件を示す。また、第２表にろ過体の空洗及び水洗条件を示す。
【００１７】
【表１】
【表２】
第２表にろ過分離槽６の処理条件を示す。本実施例では、有効面積０．３ｍ２ 、有効容積０．６ｍ３ の固液分離槽を用いた。ろ過分離槽６内部に有効面積１ｍ２ ／枚の平面形不織布ろ過体５枚をろ過体モジュール９として浸漬設置した。不織布の素材としては、ポリエステル製で、目付６０ｇ／ｍ２ 、厚み０．４ｍｍ、孔径約５０〜１００μｍのものを用いた。なお、ろ過時の平均水頭圧を約１０ｃｍとした。
図３に実施例１におけるろ過Ｆｌｕｘの経過を示す。
処理開始から約３ヵ月経過しても、ろ過Ｆｌｕｘが４．２〜４．５ｍ／ｄでほぼ一定であり、週１回の水洗を加えたことにより、安定したろ過Ｆｌｕｘが得られた。なお、ろ過水の濁度が処理期間中ほぼ５度前後であり、清澄であった。
【００２０】
比較例１
図４に実施例と同様な操作条件で、ろ過体表面に対する水洗を行わなかった場合の平均ろ過Ｆｌｕｘの経過を示す。
平均ろ過Ｆｌｕｘは、処理開始時に実施例１とほぼ同様の４．５ｍ／ｄであった。しかし、処理経過とともにろ過Ｆｌｕｘが低下した。特に処理開始から１０日後にＦｌｕｘの低下が速く、２０日後に初期値の半分の２ｍ／ｄに低下した。その後も徐々に低下し、９０日後にろ過Ｆｌｕｘが約１ｍ／ｄ以下となった。
なお、ろ過水濁度は常時１０度以下で実施例１と大きな差異は認められなかった。
【００２１】
【発明の効果】
本発明によれば、通水性ろ過体を用い、ろ過体表面に汚泥のダイナミックろ過層を形成してろ過水を得る汚泥混合液の固液分離方法において、ろ過体を浸漬するろ過分離槽の上部に設置された水洗ユニットをろ過体に面する液の流路に降下させながら、ろ過体表面に対し水洗ノズルからの水噴射を行えば、通常の空洗では完全に剥離できなかったろ過体表面の微細なフロックを容易に洗い落とすことが可能となる。洗浄後のろ過体に再び混合汚泥を供給し、ダイナミックろ過層によるろ過を行えば、初期値とほぼ同様なろ過Ｆｌｕｘが得られる。その結果、長期間にわたって、安定したろ過Ｆｌｕｘが得られ、処理水量、水質とも安定して得られる。
【００２２】
また、洗浄用の水洗ノズルがろ過体表面に対し、投射角３０〜１２０度で水を噴射することにより、ろ過体表面に付着した微細な汚泥を瞬時に洗い落とすことができ、少ない洗浄水量で良好な洗浄効果が得られる。さらに洗浄水としてはろ過水を用いれば、ろ過分離槽に新たな水を供給することなく安定した洗浄を行うことができる。
【図面の簡単な説明】
【図１】本発明の通水性ろ過体の洗浄装置を含む生物処理汚水の固液分離装置の概略説明図である。
【図２】本発明のろ過体の洗浄装置の作動状況の説明図である。
【図３】本発明の実施例１の経過日数と平均ろ過Ｆｌｕｘの関係を表すグラフを示す。
【図４】比較例１の経過日数と平均ろ過Ｆｌｕｘの関係を表すグラフを示す。
【符号の説明】
１ 流入原水
２ 生物処理槽
３ 散気管
４ 曝気ブロワ
５ 汚泥混合液ポンプ
５ａ 汚泥混合液供給バルブ
５ｂ 汚泥混合液移送バルブ
６ ろ過分離槽
７ 空洗ブロワ
８ 空洗散気管
９ 通水性ろ過体
１０ 汚泥循環液
１１ 水洗ポンプ
１２ 水洗配管
１３ ろ過水取水管
１４ 流量計
１５ 水洗ノズル（噴射ノズル）
１６ 処理水槽
１７ 水洗ユニット
１８ 排泥ライン
１９ 移動リフト[0001]
BACKGROUND OF THE INVENTION
The present invention relates to sewage treatment, and particularly relates to washing of water-permeable filter used for solid-liquid separation of activated sludge and concentration of excess sludge, and is used for treatment of organic industrial wastewater and domestic wastewater. The present invention relates to a method and apparatus for cleaning a water-permeable filter.
[0002]
[Prior art]
Conventionally, in water treatment with activated sludge, solid sludge separation of activated sludge has to be performed in order to obtain treated water. Normally, a method is used in which activated sludge is introduced into a sedimentation basin, the sludge is sedimented by gravity sedimentation, and the supernatant is discharged from the sedimentation basin as treated water. In this case, a sedimentation basin having a large sedimentation area and a long residence time that allow sufficient sedimentation to settle the activated sludge is necessary, which is a factor for increasing the size of the processing apparatus and increasing the installation volume. Moreover, when activated sludge deteriorates sedimentation property, such as a bulking, sludge flows out from a sedimentation basin and causes deterioration of treated water.
[0003]
In recent years, a method of performing solid-liquid separation of activated sludge by membrane separation instead of a sedimentation basin has been used. In this case, a microfiltration membrane or an ultrafiltration membrane is generally used as the solid-liquid separation membrane.
At that time, suction or pressurization by a pump is required as a filtration separation means, and since it is usually performed at a pressure of several tens of kPa to several hundred kPa, the power of the pump is large and the running cost is increased. In addition, clear treated water having no SS is obtained by membrane separation, while permeation flux is low, and it is necessary to periodically wash the medicine in order to prevent membrane contamination.
[0004]
Recently, as a solid-liquid separation method of activated sludge that replaces a settling pond, a method is known in which a filter body made of a breathable sheet such as a nonwoven fabric is immersed in an aeration tank to obtain filtered water with a low head pressure (Japanese Patent Laid-Open No. 5) -185078). In this case, clear filtered water can be obtained by separating the sludge formed on the filter body surface by dynamic filtration. Moreover, as a washing method of the filter body when the filtration flux is lowered, if aeration is performed from an air diffuser installed below the filter body, the sludge dynamic filtration layer formed on the surface of the filter body is easily peeled off, and stable filtration is performed. It is said that Flux is obtained.
[0005]
[Problems to be solved by the invention]
However, it was observed that the filtration flux gradually decreased when the filter body was immersed in the aeration tank and was washed only with air washing. As the number of treatment days increased, the filtration flux immediately after the flushing gradually decreased compared to the initial value. Moreover, the recovery rate which shows the ratio with respect to an initial value falls similarly, and the fall becomes large with the increase in the number of times of emptying. When the filter is immersed in an aeration tank, when the sludge dynamic filtration layer formed on the filter surface is not completely removed by air washing, fine sludge flocs adhere to the filter surface, resulting in long-term filtration. The surface of the filter body is clogged by the refinement of the attached sludge. In addition, sludge properties may be deteriorated due to adsorption or decomposition of organic substances on the attached sludge, and the formation of a biofilm on the surface of the filter body may cause a decrease in filtration flux. As a result, the cleaning effect of only air washing cannot be obtained, and the decrease in filtration flux increases with the elapsed time, making it difficult to obtain a stable treatment.
[0006]
The present invention has been made in view of such a conventional problem, and the surface of the water-permeable filter body is washed with water, and a filtration flux almost similar to the initial value can be stably obtained over a long period of time. In addition, it is an object to obtain a method and an apparatus for cleaning a filter body of a solid-liquid separation apparatus for biologically treated sewage capable of obtaining a stable amount of treated water and water quality.
[0007]
[Means for Solving the Problems]
The present inventors have made various studies on methods for always forming a uniform dynamic filtration layer on the surface of the filter body regardless of the lapse of processing time due to the above-mentioned problems.
It was confirmed that if the filtered water was sprayed from the water washing nozzle onto the surface of the filter body, it was possible to easily wash off fine flocs on the surface of the filter body that could not be completely removed by ordinary air washing.
Moreover, it has also confirmed that the fine sludge adhering to the filter body surface can be washed off instantly when the washing nozzle for washing injects wash water with respect to the filter body surface at a projection angle of 30 to 120 degrees.
Furthermore, it has been found that if mixed sludge is supplied again to the washed filter body and filtration is performed with a dynamic filtration layer, a filtration flux almost the same as the initial value can be obtained.
[0008]
The present invention has been made on the basis of such findings, and has solved the above-described problems by the following means.
(1) The raw water flows into the biological reaction tank, and after aerobic treatment with activated sludge, the activated sludge mixed solution is supplied from the biological reaction tank to the filtration separation tank in which the aqueous filter is installed, and the filtration is performed. In a solid-liquid separation method in which a sludge dynamic filtration layer is formed on the surface of the filter body in a separation tank and filtration is performed to obtain filtered water, and the activated sludge mixed liquid after filtration is returned to the biological reaction tank. When the activated sludge mixed liquid in the filtration separation tank is completely returned to the biological reaction tank, the water washing unit installed above the filter body is lowered to the liquid flow path facing the filter body, A method for washing a filter body, characterized by washing with water.
(2) The washing unit is composed of a fountain nozzle, descends to the filtration separation tank, and moves or stops the flow path of the liquid facing the filter body, and stops the projection angle 30 to 120 with respect to the filter body surface. The method for washing a filter body according to (1), wherein the filtered water is ejected from the nozzle at a degree.
[0009]
(3) In a solid-liquid separator for biologically treated sewage that uses a water-permeable filter and forms a sludge dynamic filtration layer on the surface of the filter to obtain filtered water, it is provided separately from a biological reaction tank into which sewage flows. A water-permeable filter formed with a dynamic filtration layer immersed in the filtration separation tank, an air-washing air diffuser for rinsing the filter immersed in the filter, and the activity in the filtration separation tank When the sludge mixed liquid is completely returned to the biological reaction tank, it has a water washing unit installed above the filter body for lowering the flow path of the liquid facing the filter body and washing the surface of the filter body with water. Filter body cleaning device.
(4) The washing unit is composed of a fountain nozzle and descends into the filtration separation tank, and the projection angle 30 with respect to the surface of the filter body while moving up and down the flow path of the liquid facing the filter body or when stopped. It is comprised so that filtered water may be injected from a nozzle of -120 degree | times, The washing | cleaning apparatus of the filter body of the said (3) description characterized by the above-mentioned.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, in the solid-liquid separation method of a sludge mixed liquid that uses a water-permeable filter and forms a sludge dynamic filtration layer on the surface of the filter to obtain filtrate, the upper part of the filtration separation tank in which the filter is immersed A water washing unit with a fountain nozzle is installed in the tank, and the sludge mixed liquid in the filtration separation tank is periodically returned to the biological reaction tank. After that, the water washing unit is lowered into the filtration separation tank, and the liquid facing the filter body. If the washing water is sprayed from the fountain nozzle of the water washing unit to the surface of the filter body while moving the flow path of the filter, fine sludge particles adhering to the surface of the filter body can be easily dropped. In normal air washing, when fine sludge particles adhere to the surface of the filter body and recovery of the filtration flux cannot be obtained, the filtration flux is restored to the initial value by performing the above washing method. If the sludge mixed solution is supplied again to the filtration separation tank after washing and the sludge is filtered through the dynamic filtration layer, a filtration flux almost similar to the initial value is obtained. As a result, a stable filtration flux can be obtained over a long period of time, and both the amount of treated water and water quality can be obtained stably.
[0011]
When the water washing unit does not perform water washing, the water washing unit is always installed at the upper part of the filtration separation tank and can be easily automated because it can be lowered into the filtration separation tank at the time of water washing. At that time, it is also possible to change the amount of washing, time, and frequency according to the treatment status and the properties of the sludge.
Furthermore, a washing nozzle is installed in the water washing unit, and fine sludge particles adhering to the filter body surface are instantly washed off by spraying wash water on the filter body surface at a projection angle of 30 to 120 degrees. Therefore, a good cleaning effect can be obtained with a small amount of cleaning water. Here, since filtered water is used as the washing water, stable washing can be performed without supplying new water to the filtration separation tank.
[0012]
As the water-permeable filter, if a porous pressure-resistant support is used, the same effect can be obtained by using any one of a nonwoven fabric, a woven fabric, a metal net and the like. Moreover, as a shape of a filter body, any of a plane type, a cylindrical type, and a hollow type can be used, and a plurality can be bundled and used as a module filter body.
As the target sludge that can be filtered and separated by the water-permeable filter body, any of activated sludge, agglomerated sludge, initial settling sludge, and the like are possible. Moreover, it is also possible to use as solid-liquid separation means, such as drainage with high SS and river water.
The same effect can be obtained regardless of whether the shape of the water washing unit is linear or cylindrical depending on the flow path of the liquid facing the filter. When a flat filter is used, a linear washing unit that can pass through the flow path of the liquid between the filter and the nozzles are connected in a horizontal straight line may be used. When a cylindrical filter body is used, if a cylindrical or spherical water washing unit that can enter between the filter bodies is used, automation and simplification at the time of water washing become easy.
[0013]
If the washing unit is sprayed and washed with filtered water while the water washing unit is vertically lowered and raised in the filtration tank, it can wash almost evenly on any part of the surface of the filter body. Can be effectively removed. Also, depending on the location, the water washing unit can be stopped and spray cleaning can be performed there, which is effective in locations where the amount of sludge attached is large.
When the water washing unit is vertically raised or lowered between the filter bodies installed in the filter tank, it is preferable to make the distance between the spray nozzle and the filter body constant. As the method, fixed rails that allow the water washing unit to pass vertically may be installed in advance on both sides inside the filtration tank.
The amount of water sprayed from the nozzle of the water washing unit is about 1 to 5 m 3 / m 2 / h with respect to the surface area of the filter body, and effective washing can be obtained if the water washing pressure is 100 to 200 kPa. A few minutes is sufficient for the cleaning.
[0014]
【Example】
The present invention will be specifically described below with reference to examples. However, the present invention is not limited to this example.
[0015]
Example 1
FIG. 1 is a flow sheet showing an example of a treatment method according to the present invention for a group groundwater.
As shown in FIG. 1, the inflow
[0016]
As a cleaning method for the
Table 1 shows the processing conditions of the filtration separation tank in Example 1. Table 2 shows the conditions for washing the filter body with water and washing with water.
[0017]
[Table 1]
[Table 2]
Table 2 shows the processing conditions of the
FIG. 3 shows the progress of the filtration flux in Example 1.
Even after about 3 months from the start of the treatment, the filtration flux was 4.2 to 4.5 m / d, which was almost constant. By adding water washing once a week, a stable filtration flux was obtained. In addition, the turbidity of filtered water was around 5 degrees during the treatment period, and it was clear.
[0020]
Comparative Example 1
FIG. 4 shows the course of the average filtration flux when the filter surface is not washed with water under the same operating conditions as in the example.
The average filtration flux was 4.5 m / d, which was almost the same as in Example 1 at the start of the treatment. However, the filtration flux decreased as the treatment progressed. In particular, the decrease in flux was rapid 10 days after the start of the treatment, and decreased to 2 m / d, half of the initial value, after 20 days. After that, it gradually decreased, and after 90 days, the filtration flux became about 1 m / d or less.
In addition, filtration water turbidity was always 10 degrees or less, and the big difference with Example 1 was not recognized.
[0021]
【The invention's effect】
According to the present invention, in the solid-liquid separation method of a sludge mixed liquid that uses a water-permeable filter and forms a sludge dynamic filtration layer on the surface of the filter to obtain filtrate, the upper part of the filtration separation tank in which the filter is immersed Filter unit surface that could not be completely peeled off by normal air washing if water washes from the washing nozzle to the filter surface while the water washing unit installed on the filter was lowered to the liquid flow path facing the filter body It is possible to easily wash off the fine flocs. If mixed sludge is again supplied to the filter after washing and filtration is performed by a dynamic filtration layer, a filtration flux almost the same as the initial value can be obtained. As a result, a stable filtration flux can be obtained over a long period of time, and both the amount of treated water and water quality can be obtained stably.
[0022]
In addition, the washing nozzle for washing sprays water at a projection angle of 30 to 120 degrees on the surface of the filter body, so that fine sludge adhering to the surface of the filter body can be washed off instantly, and the amount of washing water is good. Cleansing effect can be obtained. Furthermore, if filtered water is used as the washing water, stable washing can be performed without supplying new water to the filtration separation tank.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of a solid-liquid separation device for biologically treated wastewater including a washing device for a water-permeable filter according to the present invention.
FIG. 2 is an explanatory diagram of an operating state of the filter cleaning device of the present invention.
FIG. 3 is a graph showing the relationship between the number of days elapsed and the average filtration flux in Example 1 of the present invention.
4 is a graph showing the relationship between the number of days elapsed and the average filtration flux in Comparative Example 1. FIG.
[Explanation of symbols]
DESCRIPTION OF
16
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000336285A JP3606449B2 (en) | 2000-11-02 | 2000-11-02 | Filter body washing method and apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000336285A JP3606449B2 (en) | 2000-11-02 | 2000-11-02 | Filter body washing method and apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2002136845A JP2002136845A (en) | 2002-05-14 |
| JP3606449B2 true JP3606449B2 (en) | 2005-01-05 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000336285A Expired - Fee Related JP3606449B2 (en) | 2000-11-02 | 2000-11-02 | Filter body washing method and apparatus |
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| Country | Link |
|---|---|
| JP (1) | JP3606449B2 (en) |
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| JP2002136845A (en) | 2002-05-14 |
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