JP3697938B2 - Wastewater treatment equipment - Google Patents

Wastewater treatment equipment Download PDF

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JP3697938B2
JP3697938B2 JP12018799A JP12018799A JP3697938B2 JP 3697938 B2 JP3697938 B2 JP 3697938B2 JP 12018799 A JP12018799 A JP 12018799A JP 12018799 A JP12018799 A JP 12018799A JP 3697938 B2 JP3697938 B2 JP 3697938B2
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membrane
ozone
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water
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JP2000308812A (en
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繁樹 澤田
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栗田工業株式会社
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【0001】
【発明の属する技術分野】
本発明は、膜汚染の防止のために原水をオゾン酸化処理した後、膜分離処理することで、長期に亘り安定かつ効率的な運転を継続することができる用排水処理装置に係り、特に、高濁度の原水や有機コロイド成分濃度の高い原水を対象とする場合においても、オゾン使用量を抑えて効率的な処理を行うことができる用排水処理装置に関する。
【0002】
【従来の技術】
従来、用水ないし排水処理における逆浸透(RO)膜分離装置等の浄化設備の前処理システムとしては、一般的に、凝集・沈殿・砂濾過からなるシステムが採用されていたが、この前処理システムでは、原水の有機物濃度が高まると、塩化第二鉄、ポリ塩化アルミニウム、硫酸アルミニウム等の凝集剤を多量に添加する必要があるという欠点がある。また、原水の水質変動に対応した凝集剤添加量の調整が必要であり、適正な添加量制御が行われない場合には、処理水の水質が悪化するという問題もあった。
【0003】
このため、このような旧来の前処理プロセスに替わって、精密濾過(MF)膜や限外濾過(UF)膜等を用いた膜分離処理が採用されるようになってきている。MF膜やUF膜によれば、凝集剤を添加することなく、又は微量の凝集剤の添加だけで、後段のRO膜を汚染させるコロイド状成分を除去することができ、RO膜の汚染を抑止してその薬品洗浄間隔を延ばし、RO膜分離装置の運転を高効率化させることができる。
【0004】
しかし、近年、工業用水や下水道の取水水源等の有機物汚染により、用水処理における原水中には微生物代謝産物である高分子状のフミン酸やフルボ酸からなるTOC成分が増加している。このため、このような膜分離処理による前処理を行うシステムでは、前処理用のMF膜やUF膜の膜面に、原水中のTOC成分である高分子状のフミン酸やフルボ酸が吸着ないし沈着して膜を汚染させ、膜の濾過抵抗を高める傾向が増々強くなってきている。このような高分子状のフミン酸やフルボ酸による膜汚染が生じた場合には、MF膜やUF膜の洗浄法として一般的な水逆洗では除去できず、薬品洗浄を行う必要がある。
【0005】
また、排水処理設備において、下水や産業排水の生物処理水を処理して再利用する場合においても、その生物処理水中には微生物代謝産物であるフミン酸やフルボ酸からなるTOC成分が存在するため、上記と同様な問題があった。
【0006】
従来、原水中の懸濁成分を除去するために、膜濾過の前処理として凝集沈澱処理を設けることは知られているが、この場合、凝集剤として有機高分子凝集剤を用いると、その残留有機高分子凝集剤が後段の膜濾過における膜汚染を引き起こす。このため、このように有機高分子凝集剤を用いる場合には、活性炭吸着処理を設けるなどの過剰な前処理が必要とされている。
【0007】
本発明者は、このような原水中のTOC成分である高分子状のフミン酸やフルボ酸によるMF膜やUF膜の膜汚染の問題を解決すべく研究を重ねた結果、これらの膜の前段でオゾン処理を実施することにより、膜汚染を防止することができることを見出した。即ち、オゾン処理によりこれら高分子状のフミン酸やフルボ酸を分解することにより、原水中の高分子成分を減少させてMF膜やUF膜の有機物汚染を抑制させることができる。また、オゾン共存下でMF膜やUF膜に通水することにより、膜面に沈着したこれらの汚染物を酸化分解させることもでき、常に清浄な膜面を保つことで、膜の透過流束を高く維持することができる。
【0008】
しかして、本発明者はこのようなオゾン共存下でMF膜やUF膜に通水する装置において、より一層安定かつ効率的な処理を行うべく、膜の透過水の残留オゾン濃度を検出し、その値に基いてオゾン注入量を制御する方式を先に提案した(特願平10−86100号)。この特願平10−86100号公報の装置によれば、次のような作用効果が奏される。
【0009】
即ち、膜濾過の前段でオゾン酸化処理を行うことにより、膜閉塞の原因物質の一つである有機物を酸化・低分子化して膜閉塞を抑制することができる。また、オゾン処理水、即ち膜供給水にオゾンが残留している場合、オゾンによる膜面の洗浄効果が期待できる。しかし、降雨などによる急激な水質の悪化が起こった場合、この洗浄効果がなくなり、膜差圧上昇の原因となる。しかし、特願平10−86100号の装置であれば、膜透過水に常時オゾンが残留するようにするために、透過水中の残留オゾン濃度を検出するオゾン濃度検出手段を設け、このオゾン濃度検出手段により常時オゾンが検出されるように、前段のオゾン酸化処理装置のオゾン供給量を制御することにより、残留オゾンによる膜の洗浄効果を確保して、安定かつ効率的な膜分離装置の運転を長期に亘り継続して行うことが可能となる。このため、このような水質の変動が起こった際にも、膜透過水側の残留オゾンを常時確保することにより、継続的に膜面の洗浄効果を促すことができる。
【0010】
また、特開平6−328069号公報には、浄水用原水を膜分離処理し、透過水を浄水として取り出す浄水処理装置において、膜の濃縮水を原水と共に固液分離し、分離水をオゾン酸化処理した後、活性炭吸着処理して膜分離の原水として循環処理することが記載されている。この浄水処理装置では、膜濃縮水及び原水中の懸濁成分を固液分離して得られる分離水中に含まれる高分子溶存有機成分をオゾン酸化分解して低分子化すると共に、生物易分解性に変換し、この低分子化され生物易分解性となった溶存有機成分を活性炭に吸着させると共に、活性炭表面に付着した微生物により生物分解することで、膜分離原水中の高分子溶存有機成分濃度を低減し、膜の透過流束の低下を防止する。
【0011】
【発明が解決しようとする課題】
特願平10−86100号に記載されるように、膜の透過水にオゾンが残留するように、原水にオゾンを注入することにより、膜の透過流束を高く維持することができるが、高濁度の原水や有機コロイド成分濃度の高い原水を対象とする場合には、これらのコロイド懸濁成分にオゾンが消費され、過剰のオゾン供給が必要となることから、オゾン酸化処理コストが嵩むという欠点があった。
【0012】
また、特開平6−328069号公報に記載の装置では、膜濾過の前処理手段として活性炭吸着処理を必要とし、装置コスト、処理コストが高騰する。
【0013】
本発明は、このような問題点を解決し、膜汚染の防止のために原水をオゾン酸化処理した後、膜分離処理する用排水処理装置において、高濁度の原水や有機コロイド成分濃度の高い原水を対象とする場合においても、オゾン使用量を抑えて効率的なオゾン酸化処理及び膜分離処理を行うことができる用排水処理装置を提供することを目的とする。
【0014】
【課題を解決するための手段】
本発明の用排水処理装置は、用排水に有機高分子凝集剤を添加して凝集処理した後固液分離する除濁手段と、該除濁手段の処理水にオゾンを注入して酸化処理するオゾン処理手段と、該オゾン処理手段の処理水が導入される精密濾過又は限外濾過膜分離手段とを備えてなる用排水処理装置であって、前記オゾン処理手段は、該膜分離手段の透過水中にオゾンが残留するようにオゾンを注入することを特徴とする。
【0015】
本発明では、前処理手段として有機高分子凝集剤を用いた除濁手段を設けることにより、過剰のオゾンを消費する原水中のコロイド懸濁成分を予め除去した後、オゾン酸化処理し、残留オゾン共存下で膜分離手段に通水することにより、効率的な処理を行うことができる。
【0016】
【発明の実施の形態】
以下に図面を参照して本発明の実施の形態を詳細に説明する。
【0017】
図1は本発明の用排水処理装置の実施の形態を示す系統図である。
【0018】
原水はポリ塩化アルミニウム、塩化第二鉄、硫酸アルミニウム等の無機凝集剤と、ポリアクリルアミド、ポリメタクリルアミド、それらの部分加水分解物、アクリルアミド及び/又はメタクリルアミドとアクリル酸及び/又はメタクリル酸との共重合物、アクリルアミド及び/又はメタクリルアミドと2−アクリルアミド−2−ヒドロキシプロパンスルホン酸との共重合体等の有機高分子凝集剤が添加された後、沈殿槽1で固液分離される。ここで、凝集剤としては、有機高分子凝集剤のみでも良いが、無機凝集剤を併用することにより、より効率的な凝集処理を行うことができる。このように無機凝集剤を併用する場合、無機凝集剤は有機高分子凝集剤の注入点或いはそれよりも前段側に注入するのが好ましく、これにより、より一層コロイド懸濁成分の除去効率を高めることができる。なお、無機凝集剤及び有機高分子凝集剤の添加量は、原水の水質に応じて適宜決定され、特に制限はないが、通常の場合、無機凝集剤の添加量を0.1〜1000mg/L、有機高分子凝集剤の添加量を0.01〜10mg/Lとするのが好ましい。
【0019】
沈殿槽1としては、凝集沈殿槽又は凝集加圧浮上槽を用いることができ、本発明では特に凝集剤として、有機高分子凝集剤を用いることで、沈殿槽1の水面積負荷の増大による沈殿・加圧浮上の効率化を図ることができる。この有機高分子凝集剤による固液分離速度の向上効果は、加圧浮上槽で特に有効であり、従来の分離速度である5〜8m/hrという値を20m/hr程度まで高めることができる。このため、加圧浮上槽に要する設置面積を1/3程度に削減できる。
【0020】
沈殿槽1の分離汚泥は系外へ排出され、分離液は濾過槽2に送給される。この濾過槽2は必ずしも必要とされないが、これを設けることにより、コロイド懸濁成分の除去効率をより一層高め、後段の膜分離装置4の懸濁成分負荷を減少させて、膜の逆洗頻度の低下と膜に対する物理的ストレスを削減させ、運転効率の向上と膜の長寿命化を図ることができる。
【0021】
濾過槽2の濾過水は、次いでオゾン反応塔3に送給され、オゾン発生器5から供給されるオゾンにより有機成分が酸化分解処理される。
【0022】
このオゾン発生器5には、後段の膜分離装置4の透過水の取り出し配管に設けられた残留オゾン濃度計6で検出された、透過水中のオゾン濃度の検出結果が入力され、この検出結果に基いて、透過水中に残留オゾンが検出されるように、オゾン発生器5からオゾン反応塔3に注入されるオゾンの注入量が制御される。
【0023】
本発明において、このオゾン反応塔3へのオゾン注入量の制御基準となる、残留オゾン濃度計6で検出される透過水中の残留オゾン濃度は、原水の水質によっても異なるが、膜面へのファウリング物質の蓄積速度を上回る洗浄効果が発揮されるオゾン濃度、具体的には0.2〜1mg−O3/Lとするのが好ましい。残留オゾン濃度計6で検出される透過水中の残留オゾン濃度がこのような範囲となるように、オゾン反応塔3へのオゾン注入量を制御することにより、オゾンによる膜面の洗浄効果を確保して、安定した膜濾過を継続することができる。
【0024】
オゾン反応塔3では、このようなオゾン注入制御を行なって、滞留時間10〜20分程度で処理するのが好ましい。
【0025】
オゾン処理水は、次いで、膜分離装置4へ送給し、不溶物を固液分離する。
【0026】
この膜分離装置4の膜種としては、精密濾過(MF)膜、限外濾過(UF)膜を用いることができ、濃縮水の循環経路を有するクロスフロー方式のものが好適である。
【0027】
この膜分離装置4には、残留オゾンを含むオゾン処理水が流入するため、膜分離装置4の膜の材質としては、ガラスやアルミナ系のセラミック素材、金属製素材から構成される無機膜や、有機膜にあっては、四フッ化ポリエチレンや二フッ化ポリビニリデン等のフッ素系素材やポリエーテルエーテルケトン等のオゾン耐食性の強いものを用いるのが好ましい。
【0028】
膜分離装置4の濃縮水は膜分離装置の供給側へ循環され、透過水は系外へ取り出される。なお、膜透過水は、残留オゾンの除去、その他、膜分離装置4で除去し得なかった残留不純物の除去を目的として、更に活性炭吸着塔に通水して処理しても良い。
【0029】
なお、膜分離装置4では、膜分離処理を継続して行うことにより膜面に汚染物が付着して膜の透過流束が低下してくる。この場合には、膜面の逆流洗浄を行うが、本発明ではこの逆洗排水を前段の沈殿槽1に返送して原水と共に処理することにより、水回収率を高めることができる。
【0030】
【実施例】
以下に実施例及び比較例を挙げて本発明をより具体的に説明する。
【0031】
実施例1
図1に示す用排水処理装置により原水(研究所総合排水の生物処理水)の処理を行った。
【0032】
原水は50m3/dayで処理し、無機凝集剤としてポリ塩化アルミニウムを30mg/L、有機高分子凝集剤としてポリアクリルアミド系アニオンポリマーのクリフロックPA331(栗田工業(株)製)を1.0mg/L添加した後、凝集加圧浮上槽(ポンプ気泡混合方式)で20m/hrの分離速度で固液分離した。分離水を濾過槽(アンスラサイトと砂の二層濾過方式)で濾過した後、濾過水をオゾン反応塔に送給した。オゾン反応塔では、残留オゾン濃度計の検出結果に基き、オゾン発生器より、オゾン注入率10〜15mg−O3/Lの範囲で、残留オゾン濃度計で検出される透過水中のオゾン濃度が0.5〜1.0mg−O3/Lとなるように注入制御した。このオゾン反応塔の滞留時間は15分とした。
【0033】
膜分離装置の濾過膜(MF膜)としては、四フッ化ポリエチレン(PTFE)膜で公称孔径0.2μmの平膜からなるスパイラル形状の膜モジュールを用い、膜の透過流束(flux)を14m3/m2/dayとしてオゾン処理水を通水した。
【0034】
この膜分離装置では、7.5分間隔で処理水側に空気を押し込み逆洗すると共に、原水側にも空気を導入してエアスクラビングを行い、膜面の汚れを系外に排出した。
【0035】
このような処理を14日継続した後の膜の透過流束(flux)を調べ、結果を表1に示した。
【0036】
比較例1
実施例1において有機高分子凝集剤を用いなかったこと以外は同様にして処理を行い、14日処理を継続した後の膜の透過流束を調べ、結果を表1に示した。
【0037】
比較例2
実施例1において、オゾン反応塔へのオゾン注入率の制御を行わず、オゾン注入率を10mg−O3/Lで一定としたこと以外は同時に処理を行い(この比較例2では、透過水のオゾン濃度は0〜0.5mg/Lで変化した。)、14日処理を継続した後の膜の透過流束を調べ、結果を表1に示した。
【0038】
【表1】
【0039】
表1より、有機高分子凝集剤を使用すると共に、膜の透過水中にオゾンが残留するような条件下でオゾン酸化処理することで、膜分離装置の安定運転が可能であることがわかる。
【0040】
【発明の効果】
以上詳述した通り、本発明の用排水処理装置によれば、膜汚染の防止のために原水をオゾン酸化処理した後、膜分離処理する用排水処理装置において、高濁度の原水や有機コロイド成分濃度の高い原水を対象とする場合においても、オゾン使用量を抑えて効率的なオゾン酸化処理を行うことができ、オゾン酸化処理コストを押えて安定かつ効率的な膜分離装置の運転を長期に亘り継続して行うことができる。
【図面の簡単な説明】
【図1】本発明の用排水処理装置の実施の形態を示す系統図である。
【符号の説明】
1 沈殿槽
2 濾過槽
3 反応塔
4 膜分離装置
5 オゾン発生器
6 残留オゾン濃度計
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wastewater treatment apparatus for use that can continue stable and efficient operation over a long period of time by subjecting raw water to ozone oxidation treatment to prevent membrane contamination, followed by membrane separation treatment. The present invention relates to a wastewater treatment apparatus for wastewater treatment that can perform efficient treatment while suppressing the amount of ozone used, even when raw water with high turbidity or raw water with high organic colloid component concentration is targeted.
[0002]
[Prior art]
Conventionally, as a pretreatment system for purification equipment such as reverse osmosis (RO) membrane separators in water or wastewater treatment, a system comprising agglomeration, sedimentation and sand filtration has been generally adopted. Then, when the organic matter concentration of raw | natural water increases, there exists a fault that it is necessary to add a coagulant | flocculant, such as ferric chloride, polyaluminum chloride, and aluminum sulfate, in large quantities. In addition, it is necessary to adjust the addition amount of the flocculant corresponding to the water quality fluctuation of the raw water, and there is also a problem that the quality of the treated water is deteriorated when appropriate addition amount control is not performed.
[0003]
For this reason, membrane separation processing using a microfiltration (MF) membrane, an ultrafiltration (UF) membrane, or the like has been adopted instead of such a conventional pretreatment process. According to the MF membrane and UF membrane, colloidal components that contaminate the subsequent RO membrane can be removed without adding a flocculant or only by adding a small amount of flocculant, thereby suppressing contamination of the RO membrane. Thus, the chemical cleaning interval can be extended and the operation of the RO membrane separator can be made highly efficient.
[0004]
However, in recent years, due to organic contamination such as industrial water and sewer intake water sources, TOC components consisting of polymeric humic acids and fulvic acids, which are microbial metabolites, are increasing in raw water in the water treatment. For this reason, in such a system for pretreatment by membrane separation treatment, polymer humic acid or fulvic acid, which is a TOC component in raw water, is not adsorbed on the membrane surface of the MF membrane or UF membrane for pretreatment. There is an increasing tendency to deposit and contaminate the membrane and increase the filtration resistance of the membrane. When membrane contamination due to such a polymeric humic acid or fulvic acid occurs, it cannot be removed by a general water backwashing method for cleaning the MF membrane or UF membrane, and it is necessary to perform chemical cleaning.
[0005]
In addition, even when wastewater treatment facilities treat and reuse biological treated water such as sewage and industrial wastewater, the biologically treated water contains TOC components composed of humic acid and fulvic acid that are microbial metabolites. There was a problem similar to the above.
[0006]
Conventionally, in order to remove suspended components in raw water, it is known to provide a coagulation precipitation treatment as a pretreatment of membrane filtration. In this case, if an organic polymer flocculant is used as the flocculant, the residual Organic polymer flocculants cause membrane contamination in subsequent membrane filtration. For this reason, when using an organic polymer flocculant in this way, an excessive pretreatment such as providing an activated carbon adsorption treatment is required.
[0007]
The present inventor conducted research to solve the problem of membrane contamination of the MF membrane and UF membrane due to the polymer humic acid and fulvic acid that are TOC components in the raw water. The present inventors have found that film contamination can be prevented by performing ozone treatment. That is, by decomposing these polymeric humic acids and fulvic acids by ozone treatment, the polymer components in the raw water can be reduced, and organic matter contamination of the MF film and UF film can be suppressed. In addition, by passing water through the MF membrane and UF membrane in the presence of ozone, these contaminants deposited on the membrane surface can be oxidatively decomposed. By always maintaining a clean membrane surface, the permeation flux of the membrane Can be kept high.
[0008]
Therefore, the present inventor detects the residual ozone concentration of the permeated water of the membrane in order to perform more stable and efficient treatment in the apparatus that allows water to pass through the MF membrane and UF membrane in the presence of ozone, A method for controlling the ozone injection amount based on the value was previously proposed (Japanese Patent Application No. 10-86100). According to the device disclosed in Japanese Patent Application No. 10-86100, the following operational effects can be obtained.
[0009]
That is, by performing the ozone oxidation treatment before the membrane filtration, it is possible to oxidize and reduce the molecular weight of the organic substance that is one of the causative substances of the membrane clogging, thereby suppressing the membrane clogging. Further, when ozone remains in the ozone-treated water, that is, the membrane supply water, the effect of cleaning the membrane surface by ozone can be expected. However, when the water quality is suddenly deteriorated due to rain or the like, this cleaning effect is lost, causing an increase in the membrane differential pressure. However, in the case of the device of Japanese Patent Application No. 10-86100, an ozone concentration detecting means for detecting the residual ozone concentration in the permeated water is provided in order to always keep ozone in the membrane permeated water. By controlling the ozone supply amount of the preceding ozone oxidation treatment device so that ozone is always detected by the means, the membrane cleaning effect by residual ozone is secured, and stable and efficient operation of the membrane separation device is achieved. It becomes possible to carry out continuously for a long time. For this reason, even when such a change in water quality occurs, it is possible to continuously promote the effect of cleaning the membrane surface by always securing the residual ozone on the membrane permeate side.
[0010]
Japanese Patent Laid-Open No. 6-328069 discloses a water purification apparatus that performs membrane separation treatment of raw water for water purification and extracts permeated water as purified water. After that, it is described that activated carbon is adsorbed and circulated as raw water for membrane separation. In this water purification system, the polymer-dissolved organic components contained in the separated water obtained by solid-liquid separation of the suspended components in the membrane concentrated water and in the raw water are reduced by ozone oxidation and biodegradable. The dissolved organic components that have been reduced in molecular weight and become biodegradable are adsorbed on activated carbon and biodegraded by microorganisms adhering to the surface of the activated carbon. And prevents a decrease in the permeation flux of the membrane.
[0011]
[Problems to be solved by the invention]
As described in Japanese Patent Application No. 10-86100, the permeation flux of the membrane can be kept high by injecting ozone into the raw water so that ozone remains in the permeate of the membrane. When targeting raw water with high turbidity or organic colloid component concentration, ozone is consumed in these colloidal suspension components, and excessive ozone supply is required, which increases the cost of ozone oxidation treatment. There were drawbacks.
[0012]
Further, the apparatus described in JP-A-6-328069 requires an activated carbon adsorption process as a pretreatment means for membrane filtration, and the apparatus cost and the process cost are increased.
[0013]
The present invention solves such problems, and in a wastewater treatment apparatus for membrane separation treatment after raw water is subjected to ozone oxidation treatment to prevent membrane contamination, high turbidity raw water or organic colloid component concentration is high. An object of the present invention is to provide a wastewater treatment apparatus that can perform efficient ozone oxidation treatment and membrane separation treatment while suppressing the amount of ozone used even when raw water is targeted.
[0014]
[Means for Solving the Problems]
The effluent treatment apparatus of the present invention is a turbidity means for adding an organic polymer flocculant to the effluent and aggregating it, followed by solid-liquid separation, and oxidizing by injecting ozone into the treated water of the turbidity means A waste water treatment apparatus comprising ozone treatment means and microfiltration or ultrafiltration membrane separation means into which treated water of the ozone treatment means is introduced, wherein the ozone treatment means is permeated by the membrane separation means. It is characterized by injecting ozone so that ozone remains in water.
[0015]
In the present invention, by providing a turbidity removing means using an organic polymer flocculant as a pretreatment means, after removing colloidal suspended components in raw water consuming excessive ozone in advance, an ozone oxidation treatment is performed to obtain residual ozone. By passing water through the membrane separation means in the presence of coexistence, efficient treatment can be performed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0017]
FIG. 1 is a system diagram showing an embodiment of the waste water treatment apparatus of the present invention.
[0018]
The raw water is composed of inorganic flocculants such as polyaluminum chloride, ferric chloride, aluminum sulfate, polyacrylamide, polymethacrylamide, partial hydrolysates thereof, acrylamide and / or methacrylamide and acrylic acid and / or methacrylic acid. After an organic polymer flocculant such as a copolymer, a copolymer of acrylamide and / or methacrylamide and 2-acrylamido-2-hydroxypropanesulfonic acid is added, solid-liquid separation is performed in the precipitation tank 1. Here, only the organic polymer flocculant may be used as the flocculant, but more efficient flocculation treatment can be performed by using an inorganic flocculant in combination. Thus, when using an inorganic flocculant together, it is preferable to inject the inorganic flocculant at the injection point of the organic polymer flocculant or upstream of the organic polymer flocculant, thereby further improving the removal efficiency of the colloidal suspension component. be able to. The addition amount of the inorganic flocculant and the organic polymer flocculant is appropriately determined according to the quality of the raw water, and is not particularly limited. In normal cases, the addition amount of the inorganic flocculant is 0.1 to 1000 mg / L. The addition amount of the organic polymer flocculant is preferably 0.01 to 10 mg / L.
[0019]
As the sedimentation tank 1, a coagulation sedimentation tank or a coagulation pressurization flotation tank can be used. In the present invention, by using an organic polymer flocculant as the coagulant, precipitation due to an increase in water area load of the sedimentation tank 1・ It is possible to increase the efficiency of pressurized levitation. The effect of improving the solid-liquid separation speed by the organic polymer flocculant is particularly effective in the pressurized flotation tank, and the conventional separation speed of 5 to 8 m / hr can be increased to about 20 m / hr. For this reason, the installation area required for a pressure levitation tank can be reduced to about 1/3.
[0020]
The separated sludge in the settling tank 1 is discharged out of the system, and the separated liquid is fed to the filtration tank 2. Although this filtration tank 2 is not necessarily required, by providing this, the removal efficiency of the colloidal suspended component is further increased, the suspended component load of the membrane separation device 4 in the subsequent stage is reduced, and the frequency of backwashing of the membrane is increased. And physical stress on the membrane can be reduced, and the operating efficiency can be improved and the life of the membrane can be extended.
[0021]
The filtered water in the filtration tank 2 is then fed to the ozone reaction tower 3, and the organic components are oxidatively decomposed by the ozone supplied from the ozone generator 5.
[0022]
The ozone generator 5 receives the detection result of the ozone concentration in the permeated water detected by the residual ozone concentration meter 6 provided in the permeated water discharge pipe of the membrane separation device 4 at the subsequent stage. Therefore, the amount of ozone injected from the ozone generator 5 into the ozone reaction tower 3 is controlled so that residual ozone is detected in the permeated water.
[0023]
In the present invention, the residual ozone concentration in the permeated water detected by the residual ozone concentration meter 6, which is a control standard for the amount of ozone injected into the ozone reaction tower 3, varies depending on the quality of the raw water. It is preferable to set the ozone concentration at which a cleaning effect exceeding the accumulation rate of the ring substance is exhibited, specifically 0.2 to 1 mg-O 3 / L. By controlling the amount of ozone injected into the ozone reaction tower 3 so that the residual ozone concentration in the permeated water detected by the residual ozone concentration meter 6 is in such a range, the effect of cleaning the membrane surface by ozone is ensured. Thus, stable membrane filtration can be continued.
[0024]
In the ozone reaction tower 3, it is preferable to perform such ozone injection control so that the residence time is about 10 to 20 minutes.
[0025]
The ozone-treated water is then fed to the membrane separation device 4 to separate the insoluble matter into solid and liquid.
[0026]
As the membrane type of the membrane separation device 4, a microfiltration (MF) membrane or an ultrafiltration (UF) membrane can be used, and a cross flow type having a circulation path of concentrated water is preferable.
[0027]
Since ozone treated water containing residual ozone flows into the membrane separation device 4, the material of the membrane of the membrane separation device 4 is an inorganic membrane made of glass, an alumina-based ceramic material, a metal material, As the organic film, it is preferable to use a fluorine-based material such as polyethylene tetrafluoride or polyvinylidene difluoride or a material having strong ozone corrosion resistance such as polyetheretherketone.
[0028]
The concentrated water of the membrane separation device 4 is circulated to the supply side of the membrane separation device, and the permeated water is taken out of the system. The membrane permeated water may be further treated by passing it through an activated carbon adsorption tower for the purpose of removing residual ozone or other residual impurities that could not be removed by the membrane separator 4.
[0029]
In the membrane separator 4, the membrane separation process is continuously performed, so that contaminants adhere to the membrane surface and the permeation flux of the membrane decreases. In this case, backwashing of the membrane surface is performed, but in the present invention, the water recovery rate can be increased by returning the backwash wastewater to the preceding settling tank 1 and treating it with raw water.
[0030]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0031]
Example 1
The raw water (biologically treated water of the laboratory general wastewater) was treated by the wastewater treatment apparatus shown in FIG.
[0032]
The raw water was treated at 50 m 3 / day, 30 mg / L of polyaluminum chloride as an inorganic flocculant, and 1.0 mg / L of polyacrylamide anion polymer Cliff Rock PA331 (manufactured by Kurita Kogyo Co., Ltd.) as an organic polymer flocculant. After the addition of L, solid-liquid separation was carried out at a separation speed of 20 m / hr in a coagulating pressure floating tank (pump bubble mixing method). The separated water was filtered through a filtration tank (two-layer filtration method of anthracite and sand), and then the filtered water was fed to an ozone reaction tower. In the ozone reaction tower, based on the detection result of the residual ozone concentration meter, the ozone concentration in the permeated water detected by the residual ozone concentration meter is 0 within the range of the ozone injection rate of 10-15 mg-O 3 / L from the ozone generator. The injection was controlled to be 5 to 1.0 mg-O 3 / L. The residence time of this ozone reaction tower was 15 minutes.
[0033]
As a filtration membrane (MF membrane) of the membrane separation device, a spiral-shaped membrane module made of a flat membrane having a nominal pore diameter of 0.2 μm with a tetrafluoropolyethylene (PTFE) membrane is used, and the membrane permeation flux (flux) is 14 m. Ozonated water was passed as 3 / m 2 / day.
[0034]
In this membrane separator, air was pushed back into the treated water side at 7.5 minute intervals and backwashed, and air was also introduced into the raw water side to perform air scrubbing, and the dirt on the membrane surface was discharged out of the system.
[0035]
The membrane permeation flux after such treatment was continued for 14 days, and the results are shown in Table 1.
[0036]
Comparative Example 1
The treatment was performed in the same manner as in Example 1 except that the organic polymer flocculant was not used, and the permeation flux of the membrane after the 14-day treatment was examined. The results are shown in Table 1.
[0037]
Comparative Example 2
In Example 1, the ozone injection rate into the ozone reaction tower was not controlled, and treatment was performed at the same time except that the ozone injection rate was kept constant at 10 mg-O 3 / L. The ozone concentration varied from 0 to 0.5 mg / L.), The permeation flux of the membrane after 14 days of treatment was continued, and the results are shown in Table 1.
[0038]
[Table 1]
[0039]
From Table 1, it can be seen that stable operation of the membrane separation apparatus is possible by using an organic polymer flocculant and performing ozone oxidation under conditions such that ozone remains in the permeated water of the membrane.
[0040]
【The invention's effect】
As described above in detail, according to the wastewater treatment apparatus of the present invention, in order to prevent membrane contamination, the raw water is subjected to ozone oxidation treatment and then subjected to membrane separation treatment. Even when raw water with a high concentration of components is targeted, efficient ozone oxidation treatment can be performed by reducing the amount of ozone used, and stable and efficient operation of membrane separation equipment can be performed for a long time with the cost of ozone oxidation treatment suppressed. Can be continuously performed.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a waste water treatment apparatus of the present invention.
[Explanation of symbols]
1 Precipitation tank 2 Filtration tank 3 Reaction tower 4 Membrane separator 5 Ozone generator 6 Residual ozone concentration meter

Claims (3)

  1. 用排水に有機高分子凝集剤を添加して凝集処理した後固液分離する除濁手段と、
    該除濁手段の処理水にオゾンを注入して酸化処理するオゾン処理手段と、
    該オゾン処理手段の処理水が導入される精密濾過又は限外濾過膜分離手段とを備えてなる用排水処理装置であって、
    前記オゾン処理手段は、該膜分離手段の透過水中にオゾンが残留するようにオゾンを注入することを特徴とする用排水処理装置。
    Turbidity means for solid-liquid separation after adding an organic polymer flocculant to the wastewater for flocculation,
    Ozone treatment means for injecting ozone into the treated water of the turbidity removal means for oxidation treatment;
    A wastewater treatment apparatus for use comprising microfiltration or ultrafiltration membrane separation means into which treated water of the ozone treatment means is introduced,
    The waste water treatment apparatus according to claim 1, wherein the ozone treatment means injects ozone so that ozone remains in the permeated water of the membrane separation means.
  2. 請求項1において、有機高分子凝集剤と共に無機凝集剤を併用して前記凝集処理を行うことを特徴とする用排水処理装置。The wastewater treatment apparatus according to claim 1, wherein the coagulation treatment is performed using an organic coagulant and an inorganic coagulant together.
  3. 請求項1又は2において、該膜分離手段の膜材質がオゾン耐食性の強いものであることを特徴とする用排水処理装置。The wastewater treatment apparatus according to claim 1 or 2, wherein the membrane material of the membrane separation means has a strong ozone corrosion resistance.
JP12018799A 1999-04-27 1999-04-27 Wastewater treatment equipment Expired - Fee Related JP3697938B2 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102964010A (en) * 2012-12-12 2013-03-13 北京碧水源科技股份有限公司 Method for deeply treating nonbiodegradable sewage

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JP2007152272A (en) * 2005-12-07 2007-06-21 Tsukishima Kikai Co Ltd Immersed membrane filtration method and immersed membrane filtration apparatus
WO2010110065A1 (en) * 2009-03-27 2010-09-30 メタウォーター株式会社 Process for producing regenerated water and system for producing regenerated water
JP6102406B2 (en) * 2013-03-27 2017-03-29 栗田工業株式会社 Membrane separation method and membrane separation apparatus

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102964010A (en) * 2012-12-12 2013-03-13 北京碧水源科技股份有限公司 Method for deeply treating nonbiodegradable sewage

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