JP2005017098A

JP2005017098A - Water quality measuring method and water quality measuring system

Info

Publication number: JP2005017098A
Application number: JP2003181982A
Authority: JP
Inventors: Takeshi Takemoto; 剛武本; Naoki Hara; 直樹原; Shoji Watanabe; 昭二渡辺; Hiroto Yokoi; 浩人横井; Misaki Sumikura; みさき隅倉
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2003-06-26
Filing date: 2003-06-26
Publication date: 2005-01-20

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water quality measuring method and a water quality measuring system capable of grasping easily the water qualities at a plurality of spots, and enabling transient determination of a water quality abnormality or water quality maintenance of treated water. <P>SOLUTION: This method is characterized by switching from a water-intake means on an optional spot to a water-intake means on the furthermore upstream side or downstream side than it, when a measured value of a measuring object liquid taken by the water-intake means provided on the optional spot is higher than the set upper limit or lower than the lower limit, and by measuring the water quality of the measuring object liquid taken from the switched water-intake means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、水質計測方法及び水質計測システムに関する。
【０００２】
【従来の技術】
水道水等の前処理にオゾン処理を採用した際に用いられるオゾン処理装置において、オゾン濃度を測るオゾン濃度計に流入させる水を、切替電磁弁によって適宜切替える技術が特許文献１に記載されている。
【０００３】
【特許文献１】
特開平５−１６９０７３号公報
【０００４】
【発明が解決しようとする課題】
しかし、特許文献１記載の技術はオゾン濃度計に流入させる水を一定の時間間隔毎に切替えるだけであり、切替時期の制御方法については開示されていない。
【０００５】
本発明の目的は、複数地点の水質を容易に把握でき、水質異常の一過性判断または処理水の水質維持が可能な水質計測方法及び水質計測システムを提供することにある。
【０００６】
【課題を解決するための手段】
本発明は、任意の地点に設けられた取水手段より取水された計測対象液の計測値が設定された上限値を超えるかまたは下限値を下回る場合に、任意地点の取水手段より上流側または下流側の取水手段に切替え、切替えられた取水手段から取水された計測対象液の水質を計測することを特徴とする。
【０００７】
【発明の実施の形態】
下水処理場では、下水中の有機物に加えて窒素，リンも除去できる高度処理を導入し、環境保全を行っている。そこで、下水処理場の運転管理には、処理対象物質や処理に影響する物質の処理過程の濃度が重要である。
【０００８】
水質計測項目には、生物学的酸素要求量（ＢＯＤ），化学的酸素要求量（ＣＯＤ），全有機炭素（ＴＯＣ）や紫外線式化学的酸素要求量（ＵＶ−ＣＯＤ）などを指標とする有機物，全窒素（ＴＮ），アンモニア態窒素（ＮＨ_４−Ｎ），硝酸態窒素（ＮＯ_３−Ｎ）や亜硝酸態窒素（ＮＯ_２−Ｎ）などの窒素、全リン（ＴＰ）やオルトリン酸態リン（ＰＯ_４−Ｐ）のりんなどがある。そして、これらの物質の計測には、熱分解や紫外線による反応促進を併用した化学的定量法，特定波長の光を照射する吸光度法等を測定原理とした機器が実用化されている。しかし、これらの計測器は、懸濁物や定量試薬を消費する物質が存在すると大きな計測誤差を生じる。そのため、従来技術に示した水道水等の前処理とは異なり、下水処理場の生物反応槽には、懸濁する活性汚泥が混在し、活性汚泥には有機物，窒素，リンなどを含む。また、流入下水は殆ど活性汚泥を含まないが、懸濁物質を多く含む。この懸濁物質も大部分が有機物で構成されている。このため、上述した物質を正確に計測するには活性汚泥や懸濁物質を分離除去した清澄な試料を計測器に供給する必要がある。
【０００９】
また、下水処理場の運転管理の適正化には、処理水や生物反応槽内の水質計測が有効な手段であるため、処理水の異常，流入条件の変化などで運転条件を変更する時には、さらに多くの地点の水質情報が必要となる。しかし、多くの地点にそれぞれ計測器を設置すると、設備導入時のコストが増加してしまい、水質計測システムの増設は困難である。更に、下水処理場の場合は、懸濁物質と液体とを分離する固液分離装置と計測器とを各地点に設置する必要があるため、設備コストが更に増加する恐れがある。
【００１０】
さらに、清澄な試料を計測器に供給するための固液分離に膜ろ過を用いると、懸濁物の多い液体を高圧または低圧で移送する必要があり、供給手段やろ過手段の負荷が高くなる。このため、供給手段やろ過手段の故障も多くなる恐れがある。膜ろ過の前段に粗分離槽を設ける場合は、装置の増加に伴い、故障も増加し維持管理が煩雑になる恐れもある。
【００１１】
（第一の実施例）
本発明の水質計測システムを下水処理場に適用した図が図１である。本実施例では、下水処理場内を上流側から下流側に向かって計測対象液である懸濁液が流れる流路上に、生物反応槽５と沈殿池６とを備えている。そして、生物反応槽５へ流入する液体を流入水，沈殿池６から流出する液体を処理水とする。生物反応槽５には、複数の微生物群が生息する活性汚泥を有し、この生物反応槽５は複数に分割されている。生物反応槽５の前段を嫌気槽５１，嫌気槽５１の下流に無酸素槽５２，無酸素槽５２の下流に好気槽５３を設けた。好気槽５３から無酸素槽５２へ、流入水の流れに逆流する方向に反応液１００が循環する。また、沈殿池６に沈降した活性汚泥の一部は嫌気槽５１に返送汚泥１０１として循環する。この方式は一般に嫌気−無酸素−好気法と呼ばれ、流入下水中の有機物，窒素及びりんを除去できる。生物反応槽５の下流には反応液と活性汚泥とを固液分離する沈殿池６が設置されている。沈殿池６で固液分離された反応液は処理水として放流される。
【００１２】
次に、本実施例の下水処理場に設置する水質計測システムについて説明する。生物反応槽５に流入する流入水が流れる配管、嫌気槽５１，無酸素槽５２，好気槽５３，沈殿池６から放出される処理水が流れる配管には、それぞれ水質計測装置に水を取り入れるための取水手段である取水口が設置されている。計測対象液である懸濁液が流れる流路上の複数地点に設けられた取水口からは、流路１０２，１０３，１０４，１０５，１０６によって切替え装置１と接続されている。そして、懸濁液を取水する取水口を切替える切替え装置１の下流には、切替え装置１より導入された計測対象液である懸濁液を固液分離する固液分離装置２と、その下流に固液分離装置２により固体と分離された分離液を取り込み、水質を計測する計測器３とが設置されている。計測器３は有機物，窒素，りん，アルカリ度，シアン，農薬などから１項目以上計測できることが望ましい。なお、計測項目によって懸濁物質の有無が計測結果に影響を与えない場合は固液分離装置２を省略してもよい。また、処理水を計測する場合、沈殿池６での固液分離が良好であれば、切替え装置１から計測器３に直接導入しても良い。
【００１３】
計測器３の計測値はマイクロコンピュータ等からなる計測制御手段４に送られる（１０９）。計測制御手段４には、計測結果を収集・表示する機能，切替え装置１を制御するための信号を発信する機能１１０，計測対象液毎の上限値と下限値を設定でき、設定された上限値を超えるかまたは下限値を下回る場合に警報を発するまたは予め決められた地点の取水口に切替える機能とがある。切替え装置１は、電磁弁などからなる切替え弁１１，切替え弁１２，切替え弁１３，切替え弁１４及び切替え弁１５を有する。そして、本実施例では、下水処理施設内の取水口から取り入れられた水が流れる流路１０２，１０３，１０４，１０５，１０６が、それぞれ切替え弁１１，１２，１３，１４，１５と接続されている。したがって、計測制御手段４は切替え装置１内の切替え弁１１，１２，１３，１４，
１５を開閉することで計測対象液を変更できる。本実施例は切替え弁が５個あるが、２つ以上ならばいくつでも良い。
【００１４】
本実施例における切替え装置１の運用方法を説明する。計測器３には全窒素と全りんを計測できる計測器を用いている。切替え弁１１，１２，１３，１４を閉じ、切替え弁１５を開け処理水の全窒素と全りんを計測する。処理水の全窒素または全りんの計測値が設定された上限値または下限値を超えた場合に計測制御手段４はアラームを発し、水質異常を運転管理者に伝える。計測制御手段４は切替え装置１に制御信号を発信することで、切替え装置１を起動する。そして、切替え弁１５を閉じ、例えば切替え弁１１を開けることで、計測対象液を取水する取水口を切替えることができる。切替え装置１を経た流入水は、固液分離装置２に流入する。固液分離装置２から排出された流入水は計測器３で分析し、その結果を計測制御手段４に表示する。したがって、運転管理者は流入水の水質を把握できる。
【００１５】
なお、計測器３の計測間隔にもよるが、計測する計測対象液の優先順位と計測対象液の数は、予め設定しておく必要がある。活性汚泥による窒素の除去は、好気条件下での硝化反応と、嫌気条件下での脱窒反応とからなる。硝化反応は好気槽，脱窒反応は無酸素槽で主に反応が進行する。そのため、本実施例では、切替え装置１内の切替え弁１３，１４が活性汚泥による窒素除去を確認する際の制御対象となる。
【００１６】
また、活性汚泥によるりんの除去は、嫌気条件下でのりん放出反応と、好気条件下でのりん摂取反応とからなる。りん放出反応は嫌気槽，りん摂取反応は好気槽で主に反応が進行する。そのため、本実施例では、切替え装置１内の切替え弁１２，１４が活性汚泥によるりん除去を確認する際の制御対象となる。
【００１７】
このように、計測器３で全窒素と全りんを計測する場合、切替え装置１を起動し、切替え弁を切替えることで計測する計測対象液を限定できる。全窒素の代りに硝酸性窒素，有機体窒素，アンモニア性窒素でもよく、全りんの代りにオルトリン酸でも良い。したがって、設定された上限値を超えるかまたは下限値を下回る場合は、流入水や処理水に加え、窒素では無酸素槽５２，好気槽５３の計測値が、りんでは、嫌気槽５１，好気槽５３の計測値が適切な維持管理に有効であり、計測対象液の優先順位と数を予め設定できる。以上のように、運転管理に活用するために処理プロセスや計測項目毎に計測位置を予め決定し、切替え装置を制御することで、複数地点の水質を容易に把握でき、水質の適切な維持管理が可能である。
【００１８】
本実施例では、任意の地点の計測対象液に水質異常が生じた時に、この地点より上流側の水質を計測するように取水口を切替えて、計測対象液の水質を計測する。これにより、水質異常が一時的なものなのか、しばらく続くのかを把握できる。そして、必要に応じて、例えば生物反応槽５内の空気量や各反応槽間の循環流量を変更することで水質の異常に対応できる。また、水質異常の原因を推定でき、水質の適切な維持管理が行える。
【００１９】
一方、任意の地点の計測対象液に水質異常が生じた時に、この地点より下流側の水質を計測するように取水口を切替えて、計測対象液の水質を計測する。この場合、今後悪化する下流側の水質を指標に維持管理でき、処理水の水質を目標値以内に維持できる。例えば、りんは活性汚泥による除去方法以外に、凝集剤を注入することによっても除去できる。好気槽５３と沈殿池６との間に凝集剤を注入する場合には、上流側でりんの異常が検出された時に、下流側の好気槽５３のりん濃度を指標に凝集剤の注入を開始することで、放流水のりん濃度を目標値以内に維持できる。
【００２０】
（第二の実施例）
図２に、計測対象液が流れる流路を複数設置し、この流路が下流側で一つの流路に合流している時の水質計測システムの実施例を示す。一般に下水処理場では複数の反応槽を用いて下水を処理している。流入水が同じため、生物反応槽や処理水の水質は各反応槽が等しいと仮定し、水質は任意の流路における反応槽や処理水の複数地点を代表して測定する。本実施例は図１の実施例に加えて、生物反応槽５ｂと５ｃの合計３系列で下水を並列処理している。切替え弁１５を空けると沈殿池６ａの処理水、切替え弁１６を空けると沈殿池６ｂの処理水、切替え弁１７を空けると沈殿池６ｃの処理水、切替え弁１８を空けると３系列の合流した処理水を計測できる。
【００２１】
ここで、合流した流路に設置された切替え弁１８のみを空け、３系列の処理水を計測している場合について説明する。計測値が設定された上限値を超えるかまたは下限値を下回る場合は、各流路の下流側に設けられた切替え弁１５，切替え弁１６，切替え弁１７を順に開け、各系列の処理水を計測する。これにより、系列ごとの処理状況を把握でき、ある系列の不具合が処理水異常の原因か否かを判定でき、運転管理者は適切な維持管理ができる。処理水が異常と判定されたときには、まず図１に示した切替えによる水質把握を実施後、原因調査として本実施例を実施するとよい。また、切替え弁１８を設置せず、切替え弁１５，切替え弁１６，切替え弁１７のいずれか一つで処理水を計測し、異常時に他の処理水を計測するようにしてもよい。
【００２２】
（第三の実施例）
図３に本発明を用いた水質計測システムにおける他の実施例を示す。下水処理施設内の取水口から取り入れられた水が流入する切替え装置１の下流には、ポンプ等からなる取水手段７０が配置され、その下流に粗分離槽７１が配置されている。取水手段７０によって計測対象の懸濁液は粗分離槽７１に供給される。粗分離槽７１には１ｍｍから５ｍｍ程度の網目状材が設置されており、懸濁液に含まれる食品屑，種子，毛髪，木片，プラスチックやゴム等の粗大な夾雑物を除去する。また、粗分離槽７１には電磁弁，ポンプ等からなる排出手段７２が設置され、開閉またはスイッチによって粗分離槽７１の懸濁液を貯留または排出する。粗分離槽７１の下流にはポンプ等から構成され、粗分離槽を経た懸濁液を膜分離装置に供給する粗分離液供給手段７３が配置され、その下流には粗分離槽を経た懸濁液を導入し固液分離するためにＭＦ膜やＵＦ膜などからなる膜分離装置７４が配置されている。膜分離装置７４には電磁弁，ポンプ等からなる排出手段７５が設置され、開閉またはスイッチによって膜分離装置７４内の懸濁液やろ液を排出する。膜分離装置７４の下流にはポンプ等からなるろ過手段７６が設置され、その下流にろ液槽７７が設置されている。懸濁液は、膜分離装置から分離液を吸引するためのろ過手段７６の起動により膜分離装置７４でろ過され、分離液であるろ液をろ液槽７７に一時貯留する。ろ液槽７７の下流には計測器３が設置され、計測器３は所定の時間にろ液槽７７に貯留されている分離液を取り込み水質を計測する。ろ液槽７７には電磁弁，ポンプ等からなる排出手段７８が設置され、開閉またはスイッチによってろ液槽７７のろ液を貯留または排出する。このように、切替え装置１の下流側には、計測対象液を固液分離しろ過するために粗分離槽７１や膜分離装置７４，ろ液槽７７といった複数の設備と、これらの設備に計測対象液を供給する取水手段７０や粗分離液供給手段７３，ろ過手段７６といった計測対象液供給手段とが交互に配置されている。取水手段７０，粗分離液供給手段
７３，ろ過手段７６，排出手段７２，排出手段７５及び排出手段７８は、計測器の計測値を収集，表示および水質計測システムを制御する計測制御手段４によって制御される。
【００２３】
本実施例における水質計測システムの運用方法を、例えば計測対象液を流入水から嫌気槽５１に変更する場合について、図４のフローチャートを用いて説明する。初期状態は切替え弁１１が開、切替え弁１２，切替え弁１３，切替え弁１４，切替え弁１５，排出手段７２，排出手段７５，排出手段７８が閉，取水手段
７０，粗分離液供給手段７３，ろ過手段７６，計測器３が起動している。
【００２４】
まず、排水工程９０では排出手段７２，排出手段７５，排出手段７８が開き、粗分離槽７１，膜分離装置７４，ろ液槽７７の懸濁液及びろ液が排出される。また、取水手段７０のポンプ等の逆回転により、粗分離槽７１，切替え弁１１，流入水までの配管を空にする。取水手段７０に逆回転する機能が無い場合は、取水手段７０と切替え装置１との間に水道水や圧縮空気の供給口を設け、配管内を洗浄または空にする。この操作により、配管内での懸濁液の変質を防止し、切替え後の水質計測値を安定できる。所定時間経過後、取水工程９１に移行する。取水工程９１では切替え弁１１が閉じ、切替え弁１２が開き、取水手段７０が正転する。嫌気槽５１の懸濁液が切替え弁１２を経て粗分離槽７１に供給される。排出手段７２が開いているため、切替え初期の懸濁液は排出される。所定時間経過後、粗分離槽貯留工程９２に移行する。粗分離槽貯留工程９２では排出手段７２と排出手段７５が閉じる。粗分離槽７１に懸濁液が貯留され、粗分離液供給手段
７３によって粗分離槽７１を経た懸濁液が膜分離装置７４に供給されろ過を開始する。排出手段７８は開いているため、切替え初期のろ液は排出される。所定時間経過後、ろ液槽貯留工程９３に移行する。ろ液槽貯留工程９３では排出手段
７８が閉じ、ろ液槽７７にろ液が貯留される。計測器３は貯留されたろ液を採取し水質を計測する。このように、流入水の懸濁液やろ液を装置内から排出することにより、切替え操作後にろ液槽７７へ貯留されたろ液は流入水の混入がない。このため、嫌気槽５１の懸濁液の正確な計測結果が得られる。このような運用方法により、運転管理者は複数個所の正確な水質を容易に把握でき、適切な維持管理ができる。
【００２５】
上述の運用方法では、ろ液槽７７は停止しないため、膜分離装置７４が空運転となる。膜分離装置７４に使用している膜が空気に触れると疎水性となり、ろ過が困難になる場合がある。このような場合は、排水工程９０と取水工程９１で排出手段７５は開かず、粗分離液供給手段７３とろ過手段７６を停止する。そして、粗分離槽貯留工程９２の所定時間を増加させることが望ましい。なお、増加する時間は、配管内と膜分離装置７４内に残留している懸濁液やろ液が、切替え操作後の懸濁液に置換されるまでの時間を目安にするとよい。
【００２６】
（第四の実施例）
図５に本発明を適用した水質計測システムの他の実施例を示す。本実施例では、第二の実施例における切替え装置１下流側の複数の設備と計測対象液供給手段とに異常検知手段を設けている。取水手段７０の異常を検知するための取水手段異常検知手段８０，粗分離液供給手段７３の異常を検知するための粗分離液供給手段異常検知手段８１，膜分離装置７４の異常を検知するための膜分離装置異常検知手段８２，ろ過手段７６の異常を検知するためのろ過手段異常検知手段８３がそれぞれ設置されている。そして、これらの異常検知手段は漏水，過電流，過加熱などの少なくとも一つ以上を検知する。なお、漏水を検知する場合、異常検知手段同士が近接していると他の装置の漏水を検知し、誤作動になる可能性がある。このような恐れがある場合は、各装置の床を区切り水の移動を防止すると良い。また、粗分離槽７１には水位計などより構成され、粗分離槽７１の水位を検知する粗分離槽水位検知手段８４，ろ液槽７７の水位を検知するためのろ液槽水位検知手段８５が設置されている。以上の取水手段異常検知手段８０，粗分離液供給手段異常検知手段８１，膜分離装置異常検知手段８２，ろ過手段異常検知手段８３，粗分離槽水位検知手段８４，ろ液槽水位検知手段８５から得られる情報は計測制御手段４に伝えられる。図５では計測制御手段４と各装置との信号線は省略する。また、本実施例では、一部の機器が故障した時に正常な機器間で装置を稼動できるように、膜分離装置７４とろ液槽７７から粗分離槽７１へ懸濁液を供給する流路１１４，１１３を設けている。
【００２７】
本実施例における異常検知手段の運用方法について説明する。計測制御手段４は取水手段異常検知手段８０，粗分離液供給手段異常検知手段８１，膜分離装置異常検知手段８２，ろ過手段異常検知手段８３，粗分離槽水位検知手段８４，ろ液槽水位検知手段８５からの情報によって、まず異常の有無を判定する。異常があった場合は警報または異常情報を表示し、運転管理者に伝える。さらに、異常発生個所に応じて対処を施す必要がある。本実施例のように下水や活性汚泥を計測対象とした場合は、液の流れが止まると腐敗や目詰まりが発生しやすい。このため計測結果の精度を維持するためにも、異常が発生していない正常な機器は運転を継続するのが望ましい。そこで、本実施例では、水質計測システムに異常検知手段を備え、膜分離装置７４とろ液槽７７から粗分離槽７１へ懸濁液またはろ液を供給する流路１１４，１１３を設けることで、一部の機器に異常が見つかった場合にも正常な機器のみで循環運転を続けることが可能になり、補修後の運転再開も容易になる。また、計測結果の精度を確保することもできる。
【００２８】
まず、取水手段異常検知手段８０から計測制御手段４に異常を知らせる信号が送信された場合を説明する。この場合、取水手段７０に異常が発生したことになる。計測制御手段４は取水手段７０と計測器３を停止する。しかし、懸濁液とろ液は粗分離槽７１，膜分離装置７４，ろ液槽７７間を流路１１１，１１２，１１３の順に循環するため、粗分離液供給手段７３とろ過手段７６は運転を継続できる。
【００２９】
次に、粗分離液供給手段異常検知手段８１から計測制御手段４に異常を知らせる信号が送信された場合を説明する。この場合、粗分離液供給手段７３に異常が発生したことになる。計測制御手段４は粗分離液供給手段７３，ろ過手段７６及び計測器３を停止する。さらに、計測制御手段４は排出手段７５と排出手段７８を開け、膜分離装置７４とろ液槽７７を空にする。これにより、切替え装置１，取水手段７０及び粗分離槽７１は運転を継続し、膜分離装置７４とろ液槽７７の懸濁液及びろ液の腐敗や変質を防止できる。
【００３０】
次に、膜分離装置異常検知手段８２から計測制御手段４に異常を知らせる信号が送信された場合を説明する。この場合、膜分離装置７４に異常が発生したことになる。計測制御手段４は粗分離液供給手段７３，ろ過手段７６及び計測器３を停止する。さらに、計測制御手段４は排出手段７５と排出手段７８を開け、膜分離装置７４とろ液槽７７を空にする。これにより、切替え装置１，取水手段７０及び粗分離槽７１は運転を継続し、膜分離装置７４とろ液槽７７の懸濁液及びろ液の腐敗や変質を防止できる。
【００３１】
次に、ろ過手段異常検知手段８３から計測制御手段４に異常を知らせる信号が送信された場合を説明する。この場合、ろ過手段７６に異常が発生したことになる。計測制御手段４はろ過手段７６と計測器３を停止し、排出手段７８を開け、ろ液槽７７を空にする。これにより、ろ過手段７６の上流は異常がないため運転を継続でき、粗分離槽７１と膜分離装置７４との流路１１１，１１４を懸濁液が循環運転される。また、ろ液槽７７内は空であるため、ろ液槽７７の腐敗や変質を防止できる。
【００３２】
粗分離槽水位検知手段８４によって粗分離槽７１の水位低下を検出した信号が計測制御手段４に送信された場合を説明する。この場合、取水手段７０の流量が低下したことになる。そのため、計測制御手段４は取水手段７０の流量を所定量だけ増加させる。所定時間後に再度粗分離槽７１の水位を検出する。水位が回復していない場合、計測制御手段４は取水手段７０の流量を所定量だけさらに増加させる。取水手段７０の流量が最大値に達した場合は、取水手段７０が異常とみなし、上述の取水手段７０に異常が発生した場合と同様の対策をとる。
【００３３】
次に、ろ液槽水位検知手段８５によって、ろ液槽７７の水位低下を検出した信号を計測制御手段４に送信した場合を説明する。この場合、膜分離装置７４のろ過流量が低下したことが原因である。計測制御手段４は粗分離液供給手段７３の流量を所定量だけ増加させる。所定時間後に再度ろ液槽７７の水位を検出する。水位が回復していない場合、計測制御手段４は粗分離液供給手段７３の流量を所定量だけ増加する。粗分離液供給手段７３の流量が最大値に達した場合は、ろ過手段７６の流量を所定量だけ増加する。所定時間後に再度ろ液槽７７の水位を検出する。水位が回復していない場合、計測制御手段４はろ過手段７６の流量を所定量だけ増加させる。ろ過手段７６の流量が最大値に達した場合、計測制御手段４は膜分離装置７４の膜が劣化したと判定し、膜の洗浄または交換を運転管理者に知らせる。このように、切替え装置下流側の複数の設備と計測対象液供給手段にそれぞれ異常検知手段を備えることで、故障個所判定機能が付加でき維持管理を容易にできる。
【００３４】
なお、膜分離装置７４を流れるろ過流量を増加させる手段には、膜分離装置
７４への供給圧力を増加させる方法と吸引圧力を増加させる方法とがある。供給圧力を増加させるには、膜分離装置７４上流側に設置された粗分離液供給手段
７３の流量を増加させる。吸引圧力を増加させるには、膜分離装置７４下流側に設置されたろ過手段７６の流量を増加させる。このように、ろ過流量を増加させる手段として、粗分離粗液供給手段７３またはろ過手段７６の流量を増加させる方法があるが、計測制御手段４は粗分離液供給手段７３における流量増加を優先させる。これは粗分離液の流れには、膜分離装置７４内のろ過膜表面を洗浄する効果があるためである。
【００３５】
（第五の実施例）
図６に本発明を適用した水質計測システムにおける他の実施例を示す。第三の実施例との違いは流路１１２ａにおけるろ過手段７６の有無である。膜分離装置７４下流側でろ液が得られるのは、膜分離装置７４内に具備されている膜を挟んで、通過する処理水の供給側（上流側）とろ液側（下流側）に圧力差が発生してろ過が進行するためである。第三の実施例ではろ過手段７６を設置することで、膜分離装置７４のろ液側（下流側）を負圧にしてろ過していた。しかし、本実施例では膜分離装置７４のろ過液側（下流側）を開放して大気圧とし、粗分離液供給手段７３の供給圧を活用して、膜の前後に圧力差を発生させ、ろ過している。粗分離液供給手段７３から懸濁液を供給する時の供給圧は、粗分離液供給手段
７３の流量，膜分離装置７４から粗分離槽７１に戻る配管１１４の径や長さなどによって調節できる。例えば、膜分離装置７４から排出されるろ液量が低下した場合には、膜分離装置７４から粗分離槽７１に戻る配管１１４を延長すれば良い。粗分離液供給手段７３の供給圧が増加するため、膜の圧力差が増加し、必要なろ液量を確保できる。本実施例によりろ過手段７６を省略できることで設備コストの低減が図れ、ろ過手段７６の維持管理をなくすことで設備全体の維持管理を容易にできる。
【００３６】
【発明の効果】
本発明によると、複数地点の水質を容易に把握でき、水質異常の一過性判断または処理水の水質維持が可能な水質計測方法及び水質計測システムを提供することが可能である。
【図面の簡単な説明】
【図１】第一の実施例における水質計測システムの構成図である。
【図２】第二の実施例における水質計測システムの構成図である。
【図３】第三の実施例における水質計測システムの構成図である。
【図４】第三の実施例における水質計測システムの運用方法を示したフローチャートである。
【図５】第四の実施例における水質計測システムの構成図である。
【図６】第五の実施例における水質計測システムの構成図である。
【符号の説明】
１…切替え装置、２…固液分離装置、３…計測器、４…計測制御手段、５…生物反応槽、６…沈殿池、１１，１２，１３，１４，１５…切替え弁、５１…嫌気槽、５２…無酸素槽、５３…好気槽、７０…取水手段、７１…粗分離槽、７２，７５，７８…排出手段、７３…粗分離液供給手段、７４…膜分離装置、７６…ろ過手段、７７…ろ液槽、８０…取水手段異常検知手段、８１…粗分離液供給手段異常検知手段、８２…膜分離装置異常検知手段、８３…ろ過手段異常検知手段、８４…粗分離槽水位検知手段、８５…ろ液槽水位検知手段、９０…排水工程、９１…取水工程、９２…粗分離槽貯留工程、９３…ろ液槽貯留工程。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water quality measurement method and a water quality measurement system.
[0002]
[Prior art]
Patent Document 1 describes a technique for appropriately switching water flowing into an ozone concentration meter that measures ozone concentration by using a switching electromagnetic valve in an ozone treatment apparatus used when ozone treatment is adopted for pretreatment of tap water or the like. .
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 5-169073
[0004]
[Problems to be solved by the invention]
However, the technique described in Patent Document 1 only switches the water flowing into the ozone concentration meter at certain time intervals, and does not disclose a method for controlling the switching timing.
[0005]
An object of the present invention is to provide a water quality measurement method and a water quality measurement system capable of easily grasping the water quality at a plurality of points and making a transient determination of water quality abnormality or maintaining the quality of treated water.
[0006]
[Means for Solving the Problems]
In the present invention, when the measured value of the liquid to be measured taken from the water intake means provided at an arbitrary point exceeds the set upper limit value or falls below the lower limit value, the upstream side or the downstream side from the water intake means at the arbitrary point. It switches to the water intake means of the side, and measures the water quality of the liquid to be measured taken from the switched water intake means.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
At the sewage treatment plant, advanced treatment that can remove nitrogen and phosphorus in addition to organic matter in sewage is introduced to protect the environment. Therefore, in the operation management of the sewage treatment plant, the concentration of the treatment process of the substance to be treated and the substance affecting the treatment is important.
[0008]
The water quality measurement items include organic substances that use biological oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (TOC), ultraviolet chemical oxygen demand (UV-COD), etc. as indicators. , Total nitrogen (TN), ammonia nitrogen (NH ₄ -N), nitrate nitrogen (NO) ₃ -N) and nitrite nitrogen (NO) ₂ -N) nitrogen, total phosphorus (TP) and orthophosphoric phosphorus (PO) ₄ -P) and the like. For measuring these substances, instruments based on the measurement principle such as a chemical quantification method combined with thermal decomposition and reaction acceleration by ultraviolet rays, an absorbance method of irradiating light of a specific wavelength, and the like have been put into practical use. However, these measuring instruments cause a large measurement error if there is a substance that consumes a suspended solid or a quantitative reagent. Therefore, unlike pretreatment such as tap water shown in the prior art, the activated sludge suspended in the biological reaction tank of the sewage treatment plant contains organic matter, nitrogen, phosphorus and the like. Inflow sewage contains almost no activated sludge but contains a lot of suspended solids. Most of this suspended substance is also composed of organic matter. For this reason, in order to accurately measure the above-mentioned substances, it is necessary to supply a clear sample from which activated sludge and suspended substances are separated and removed to the measuring instrument.
[0009]
In addition, measuring water quality in the treated water and biological reaction tank is an effective means for optimizing the operation management of the sewage treatment plant, so when changing operating conditions due to abnormalities in treated water, changes in inflow conditions, etc. More water quality information is needed at many points. However, if measuring instruments are installed at many points, the cost for introducing the equipment increases, and it is difficult to add a water quality measuring system. Furthermore, in the case of a sewage treatment plant, it is necessary to install a solid-liquid separation device and a measuring instrument for separating suspended substances and liquid at each point, which may further increase the equipment cost.
[0010]
Furthermore, when membrane filtration is used for solid-liquid separation to supply a clear sample to a measuring instrument, it is necessary to transport a liquid with a large amount of suspension at high pressure or low pressure, which increases the load on the supply means and the filtration means. . For this reason, there is a possibility that the failure of the supply means and the filtration means will increase. In the case where a rough separation tank is provided at the front stage of membrane filtration, as the number of apparatuses increases, failures may increase and maintenance management may become complicated.
[0011]
(First embodiment)
FIG. 1 is a diagram in which the water quality measurement system of the present invention is applied to a sewage treatment plant. In this embodiment, the biological reaction tank 5 and the sedimentation tank 6 are provided on the flow path through which the suspension as the measurement target liquid flows from the upstream side toward the downstream side in the sewage treatment plant. And let the liquid which flows in into the biological reaction tank 5 be inflow water, and let the liquid which flows out from the sedimentation basin 6 be treated water. The biological reaction tank 5 has activated sludge inhabited by a plurality of microorganism groups, and the biological reaction tank 5 is divided into a plurality of parts. An anaerobic tank 51 is provided downstream of the anaerobic tank 51, and an aerobic tank 53 is provided downstream of the anaerobic tank 52. The reaction solution 100 circulates from the aerobic tank 53 to the oxygen-free tank 52 in the direction of flowing backward to the flow of the inflowing water. A part of the activated sludge that has settled in the settling tank 6 circulates in the anaerobic tank 51 as return sludge 101. This method is generally called an anaerobic-anoxic-aerobic method and can remove organic substances, nitrogen and phosphorus in the inflowing sewage. A sedimentation basin 6 for separating the reaction liquid and activated sludge into solid and liquid is installed downstream of the biological reaction tank 5. The reaction liquid separated into solid and liquid in the sedimentation basin 6 is discharged as treated water.
[0012]
Next, a water quality measurement system installed in the sewage treatment plant of this embodiment will be described. Water is introduced into the water quality measuring device into the pipe through which the inflow water flowing into the biological reaction tank 5 flows, the anaerobic tank 51, the anoxic tank 52, the aerobic tank 53, and the pipe through which the treated water discharged from the sedimentation basin 6 flows. A water intake, which is a water intake means, is installed. From the intake ports provided at a plurality of points on the flow path through which the suspension as the measurement target liquid flows, the switching apparatus 1 is connected by flow paths 102, 103, 104, 105, and 106. Then, downstream of the switching device 1 for switching the water intake port for taking the suspension, the solid-liquid separation device 2 for solid-liquid separation of the suspension, which is the measurement target liquid introduced from the switching device 1, and the downstream thereof A measuring instrument 3 that takes in the separated liquid separated from the solid by the solid-liquid separator 2 and measures the water quality is installed. It is desirable that the measuring device 3 can measure one or more items from organic matter, nitrogen, phosphorus, alkalinity, cyanide, agricultural chemicals and the like. Note that the solid-liquid separation device 2 may be omitted when the presence or absence of suspended solids does not affect the measurement result depending on the measurement item. Moreover, when measuring treated water, if the solid-liquid separation in the sedimentation basin 6 is favorable, you may introduce | transduce directly to the measuring device 3 from the switching apparatus 1. FIG.
[0013]
The measurement value of the measuring instrument 3 is sent to the measurement control means 4 comprising a microcomputer or the like (109). The measurement control means 4 can set a function for collecting and displaying measurement results, a function 110 for transmitting a signal for controlling the switching device 1, and an upper limit value and a lower limit value for each measurement target liquid. There is a function of issuing an alarm when the value exceeds or falls below the lower limit value or switching to a water intake at a predetermined point. The switching device 1 includes a switching valve 11, a switching valve 12, a switching valve 13, a switching valve 14, and a switching valve 15 including electromagnetic valves. In this embodiment, the flow paths 102, 103, 104, 105, and 106 through which the water taken from the water intake in the sewage treatment facility flows are connected to the switching valves 11, 12, 13, 14, and 15, respectively. Yes. Therefore, the measurement control means 4 has the switching valves 11, 12, 13, 14, in the switching device 1.
The liquid to be measured can be changed by opening and closing 15. In this embodiment, there are five switching valves, but any number is possible as long as there are two or more.
[0014]
An operation method of the switching device 1 in the present embodiment will be described. The measuring instrument 3 uses a measuring instrument capable of measuring total nitrogen and total phosphorus. The switching valves 11, 12, 13, and 14 are closed, the switching valve 15 is opened, and the total nitrogen and total phosphorus in the treated water are measured. When the measured value of total nitrogen or total phosphorus of the treated water exceeds the set upper limit value or lower limit value, the measurement control means 4 issues an alarm and informs the operation manager of the water quality abnormality. The measurement control means 4 activates the switching device 1 by transmitting a control signal to the switching device 1. Then, by closing the switching valve 15 and opening the switching valve 11, for example, the water intake port for taking in the liquid to be measured can be switched. Inflow water that has passed through the switching device 1 flows into the solid-liquid separation device 2. The inflow water discharged from the solid-liquid separator 2 is analyzed by the measuring device 3 and the result is displayed on the measurement control means 4. Therefore, the operation manager can grasp the quality of the influent water.
[0015]
Although it depends on the measurement interval of the measuring instrument 3, the priority order of the liquid to be measured and the number of liquids to be measured need to be set in advance. Removal of nitrogen by activated sludge consists of a nitrification reaction under aerobic conditions and a denitrification reaction under anaerobic conditions. The nitrification reaction proceeds mainly in an aerobic tank and the denitrification reaction mainly in an anoxic tank. For this reason, in this embodiment, the switching valves 13 and 14 in the switching device 1 are controlled when confirming nitrogen removal by activated sludge.
[0016]
The removal of phosphorus by activated sludge consists of a phosphorus release reaction under anaerobic conditions and a phosphorus uptake reaction under aerobic conditions. The reaction mainly proceeds in the anaerobic tank for the phosphorus release reaction and in the aerobic tank for the phosphorus intake reaction. For this reason, in this embodiment, the switching valves 12 and 14 in the switching device 1 are controlled when the removal of phosphorus by activated sludge is confirmed.
[0017]
Thus, when measuring the total nitrogen and total phosphorus with the measuring instrument 3, the measuring object liquid to measure can be limited by starting the switching apparatus 1 and switching a switching valve. Instead of total nitrogen, nitrate nitrogen, organic nitrogen and ammonia nitrogen may be used, and orthophosphoric acid may be used instead of total phosphorus. Therefore, when the set upper limit value is exceeded or falls below the lower limit value, in addition to the inflowing water and treated water, the measured values of the anaerobic tank 52 and the aerobic tank 53 for nitrogen, and the anaerobic tank 51 for the phosphorus, The measurement value of the air tank 53 is effective for appropriate maintenance, and the priority order and number of the liquids to be measured can be set in advance. As described above, by determining the measurement position for each processing process and measurement item in advance for use in operation management and controlling the switching device, the water quality at multiple points can be easily grasped, and appropriate maintenance of water quality is maintained. Is possible.
[0018]
In this embodiment, when a water quality abnormality occurs in the measurement target liquid at an arbitrary point, the water intake of the measurement target liquid is switched by switching the intake port so as to measure the water quality upstream of this point. Thereby, it is possible to grasp whether the water quality abnormality is temporary or continues for a while. And if necessary, for example, it is possible to cope with abnormal water quality by changing the amount of air in the biological reaction tank 5 and the circulation flow rate between the reaction tanks. In addition, the cause of water quality abnormality can be estimated, and appropriate water quality maintenance can be performed.
[0019]
On the other hand, when a water quality abnormality occurs in the liquid to be measured at an arbitrary point, the water intake is switched so as to measure the water quality downstream from this point, and the water quality of the liquid to be measured is measured. In this case, the downstream water quality that will deteriorate in the future can be maintained and managed, and the quality of the treated water can be maintained within the target value. For example, phosphorus can be removed by injecting a flocculant in addition to the removal method using activated sludge. When the flocculant is injected between the aerobic tank 53 and the sedimentation basin 6, when an abnormality in phosphorus is detected on the upstream side, the flocculant is injected using the phosphorus concentration in the downstream aerobic tank 53 as an index. By starting the process, the phosphorus concentration of the discharged water can be maintained within the target value.
[0020]
(Second embodiment)
FIG. 2 shows an embodiment of a water quality measurement system in which a plurality of flow paths through which the measurement target liquid flows are installed and the flow paths merge into one flow path on the downstream side. Generally, a sewage treatment plant treats sewage using a plurality of reaction tanks. Since the inflow water is the same, the water quality of the biological reaction tank and the treated water is assumed to be the same in each reaction tank, and the water quality is measured on behalf of a plurality of points in the reaction tank and the treated water in an arbitrary flow path. In this embodiment, in addition to the embodiment of FIG. 1, sewage is processed in parallel in a total of three series of biological reaction tanks 5b and 5c. When the switching valve 15 is opened, the treated water in the settling basin 6a is opened. When the switching valve 16 is opened, the treated water in the settling basin 6b is opened. When the switching valve 17 is opened, the treated water in the settling basin 6c is opened. Treated water can be measured.
[0021]
Here, a case will be described in which only the switching valve 18 installed in the joined flow path is opened and three series of treated water are measured. When the measured value exceeds the set upper limit value or falls below the lower limit value, the switching valve 15, the switching valve 16, and the switching valve 17 provided on the downstream side of each flow path are sequentially opened, and the treated water of each series is discharged. measure. As a result, it is possible to grasp the processing status for each series, determine whether or not a certain series of defects is the cause of the treated water abnormality, and the operation manager can perform appropriate maintenance. When it is determined that the treated water is abnormal, the present embodiment may be implemented as a cause investigation after first grasping the water quality by the switching shown in FIG. Alternatively, the switching water 18 may not be installed, and the treated water may be measured by any one of the switching valve 15, the switching valve 16, and the switching valve 17, and the other treated water may be measured in the event of an abnormality.
[0022]
(Third embodiment)
FIG. 3 shows another embodiment of the water quality measurement system using the present invention. A water intake means 70 such as a pump is disposed downstream of the switching device 1 into which water taken from a water intake in the sewage treatment facility flows, and a coarse separation tank 71 is disposed downstream thereof. The suspension to be measured is supplied to the rough separation tank 71 by the water intake means 70. The coarse separation tank 71 is provided with a net-like material of about 1 mm to 5 mm, and removes coarse impurities such as food waste, seeds, hair, wood chips, plastic and rubber contained in the suspension. The coarse separation tank 71 is provided with a discharge means 72 comprising an electromagnetic valve, a pump, etc., and the suspension in the coarse separation tank 71 is stored or discharged by opening / closing or a switch. A coarse separation liquid supply means 73 is arranged downstream of the coarse separation tank 71 and includes a pump and the like, and supplies the suspension that has passed through the coarse separation tank to the membrane separation device. A membrane separation device 74 made of an MF membrane, a UF membrane, or the like is disposed to introduce a liquid and perform solid-liquid separation. The membrane separator 74 is provided with a discharge means 75 comprising an electromagnetic valve, a pump, etc., and the suspension and filtrate in the membrane separator 74 are discharged by opening and closing or a switch. A filtration means 76 composed of a pump or the like is installed downstream of the membrane separation device 74, and a filtrate tank 77 is installed downstream thereof. The suspension is filtered by the membrane separation device 74 when the filtration means 76 for sucking the separation liquid from the membrane separation device is activated, and the filtrate as the separation liquid is temporarily stored in the filtrate tank 77. The measuring instrument 3 is installed downstream of the filtrate tank 77, and the measuring instrument 3 takes in the separated liquid stored in the filtrate tank 77 at a predetermined time and measures the water quality. The filtrate tank 77 is provided with a discharge means 78 including a solenoid valve, a pump and the like, and the filtrate in the filtrate tank 77 is stored or discharged by opening / closing or a switch. As described above, on the downstream side of the switching device 1, a plurality of facilities such as the coarse separation tank 71, the membrane separation device 74, and the filtrate tank 77 are measured in these facilities in order to separate and filter the liquid to be measured. Measurement target liquid supply means such as water intake means 70 for supplying the target liquid, coarse separated liquid supply means 73 and filtration means 76 are alternately arranged. Water intake means 70, coarse separated liquid supply means
73, the filtration means 76, the discharge means 72, the discharge means 75, and the discharge means 78 are controlled by the measurement control means 4 for collecting, displaying, and controlling the water quality measurement system.
[0023]
The operation method of the water quality measurement system in the present embodiment will be described with reference to the flowchart of FIG. 4, for example, when the measurement target liquid is changed from the inflow water to the anaerobic tank 51. In the initial state, the switching valve 11 is open, the switching valve 12, the switching valve 13, the switching valve 14, the switching valve 15, the discharge means 72, the discharge means 75, and the discharge means 78 are closed, and the water intake means
70, the coarse separation liquid supply means 73, the filtration means 76, and the measuring instrument 3 are activated.
[0024]
First, in the drainage process 90, the discharge means 72, the discharge means 75, and the discharge means 78 are opened, and the suspension and filtrate of the coarse separation tank 71, the membrane separation device 74, and the filtrate tank 77 are discharged. Further, the reverse separation of the pump or the like of the water intake means 70 empties the rough separation tank 71, the switching valve 11, and the piping to the inflow water. When the water intake means 70 does not have a reverse rotation function, a tap water or compressed air supply port is provided between the water intake means 70 and the switching device 1 to clean or empty the piping. By this operation, the suspension is prevented from being altered in the pipe, and the water quality measurement value after switching can be stabilized. After a predetermined time has elapsed, the process proceeds to the water intake step 91. In the water intake step 91, the switching valve 11 is closed, the switching valve 12 is opened, and the water intake means 70 is rotated forward. The suspension in the anaerobic tank 51 is supplied to the coarse separation tank 71 through the switching valve 12. Since the discharging means 72 is open, the suspension at the beginning of switching is discharged. After a predetermined time has elapsed, the process proceeds to the coarse separation tank storage step 92. In the coarse separation tank storage step 92, the discharge means 72 and the discharge means 75 are closed. The suspension is stored in the coarse separation tank 71, and the coarse separation liquid supply means
73, the suspension that has passed through the coarse separation tank 71 is supplied to the membrane separation device 74, and filtration is started. Since the discharging means 78 is open, the filtrate at the beginning of switching is discharged. After a predetermined time has elapsed, the flow proceeds to the filtrate tank storage step 93. In the filtrate tank storage step 93, the discharge means
78 is closed, and the filtrate is stored in the filtrate tank 77. The measuring instrument 3 collects the stored filtrate and measures the water quality. Thus, by discharging the suspension and filtrate of the influent water from the inside of the apparatus, the filtrate stored in the filtrate tank 77 after the switching operation is not mixed with the influent water. For this reason, an accurate measurement result of the suspension in the anaerobic tank 51 is obtained. With such an operation method, the operation manager can easily grasp the accurate water quality at a plurality of locations, and can perform appropriate maintenance.
[0025]
In the above operation method, since the filtrate tank 77 does not stop, the membrane separation device 74 is idle. When the membrane used in the membrane separation device 74 is exposed to air, it becomes hydrophobic and may be difficult to filter. In such a case, the discharge means 75 is not opened in the drainage step 90 and the water intake step 91, and the rough separated liquid supply means 73 and the filtration means 76 are stopped. And it is desirable to increase the predetermined time of the rough separation tank storage process 92. Note that the increasing time may be based on the time until the suspension or filtrate remaining in the pipe and the membrane separation device 74 is replaced with the suspension after the switching operation.
[0026]
(Fourth embodiment)
FIG. 5 shows another embodiment of a water quality measurement system to which the present invention is applied. In the present embodiment, abnormality detection means are provided in the plurality of facilities and the measurement target liquid supply means on the downstream side of the switching device 1 in the second embodiment. In order to detect an abnormality in the water intake means 70 for detecting an abnormality in the water intake means 70, an abnormality detection means 81 in the coarse separation liquid supply means 81 for detecting an abnormality in the coarse liquid supply means 73, and an abnormality in the membrane separation device 74. The membrane separation device abnormality detection means 82 and the filtration means abnormality detection means 83 for detecting the abnormality of the filtration means 76 are respectively installed. These abnormality detection means detect at least one of water leakage, overcurrent, overheating, and the like. In addition, when detecting a water leak, if the abnormality detection means are close to each other, a water leak from another device may be detected and a malfunction may occur. When there is such a fear, it is good to separate the floor of each apparatus and prevent the movement of water. The coarse separation tank 71 is composed of a water level meter or the like, and comprises a coarse separation tank water level detection means 84 for detecting the water level of the coarse separation tank 71, and a filtrate tank water level detection means 85 for detecting the water level of the filtrate tank 77. Is installed. From the water intake means abnormality detection means 80, the coarse separation liquid supply means abnormality detection means 81, the membrane separation apparatus abnormality detection means 82, the filtration means abnormality detection means 83, the coarse separation tank water level detection means 84, and the filtrate tank water level detection means 85. The obtained information is transmitted to the measurement control means 4. In FIG. 5, signal lines between the measurement control means 4 and each device are omitted. Further, in this embodiment, the flow path 114 for supplying the suspension from the membrane separation device 74 and the filtrate tank 77 to the coarse separation tank 71 so that the apparatus can be operated between normal apparatuses when a part of the devices fails. , 113 are provided.
[0027]
An operation method of the abnormality detection means in the present embodiment will be described. The measurement control means 4 includes a water intake means abnormality detection means 80, a coarse separation liquid supply means abnormality detection means 81, a membrane separation device abnormality detection means 82, a filtration means abnormality detection means 83, a coarse separation tank water level detection means 84, and a filtrate tank water level detection. Based on the information from the means 85, the presence or absence of an abnormality is first determined. If there is an abnormality, display an alarm or abnormality information and inform the operation manager. Furthermore, it is necessary to take measures according to the location where the abnormality occurred. In the case where sewage and activated sludge are to be measured as in this embodiment, when the flow of the liquid stops, rot and clogging are likely to occur. For this reason, in order to maintain the accuracy of the measurement result, it is desirable to continue the operation of a normal device in which no abnormality has occurred. Therefore, in this embodiment, the water quality measurement system is provided with abnormality detection means, and by providing the flow path 114, 113 for supplying the suspension or filtrate from the membrane separation device 74 and the filtrate tank 77 to the coarse separation tank 71, Even if an abnormality is found in some devices, it is possible to continue the circulating operation only with normal devices, and it becomes easy to resume operation after repair. It is also possible to ensure the accuracy of measurement results.
[0028]
First, the case where the signal which notifies abnormality to the measurement control means 4 is transmitted from the water intake means abnormality detection means 80 is demonstrated. In this case, an abnormality has occurred in the water intake means 70. The measurement control means 4 stops the water intake means 70 and the measuring instrument 3. However, since the suspension and the filtrate circulate between the coarse separation tank 71, the membrane separation device 74, and the filtrate tank 77 in the order of the flow paths 111, 112, and 113, the coarse separation liquid supply means 73 and the filtration means 76 are operated. Can continue.
[0029]
Next, the case where a signal notifying the abnormality to the measurement control means 4 is transmitted from the rough separation liquid supply means abnormality detection means 81 will be described. In this case, an abnormality has occurred in the coarse separation liquid supply means 73. The measurement control means 4 stops the coarse separation liquid supply means 73, the filtration means 76, and the measuring instrument 3. Further, the measurement control means 4 opens the discharge means 75 and the discharge means 78 and empties the membrane separation device 74 and the filtrate tank 77. Thereby, the switching device 1, the water intake means 70, and the rough separation tank 71 can continue to operate, and the suspension and deterioration of the suspension and filtrate of the membrane separation apparatus 74 and the filtrate tank 77 can be prevented.
[0030]
Next, a case where a signal notifying the abnormality to the measurement control means 4 is transmitted from the membrane separation apparatus abnormality detection means 82 will be described. In this case, an abnormality has occurred in the membrane separation device 74. The measurement control means 4 stops the coarse separation liquid supply means 73, the filtration means 76, and the measuring instrument 3. Further, the measurement control means 4 opens the discharge means 75 and the discharge means 78 and empties the membrane separation device 74 and the filtrate tank 77. Thereby, the switching device 1, the water intake means 70, and the rough separation tank 71 can continue to operate, and the suspension and deterioration of the suspension and filtrate of the membrane separation apparatus 74 and the filtrate tank 77 can be prevented.
[0031]
Next, a case where a signal notifying the abnormality to the measurement control means 4 is transmitted from the filtration means abnormality detection means 83 will be described. In this case, an abnormality has occurred in the filtering means 76. The measurement control means 4 stops the filtration means 76 and the measuring instrument 3, opens the discharge means 78, and empties the filtrate tank 77. Thereby, since there is no abnormality upstream of the filtration means 76, the operation can be continued, and the suspension is circulated through the flow paths 111, 114 between the coarse separation tank 71 and the membrane separation device 74. Further, since the inside of the filtrate tank 77 is empty, the filtrate tank 77 can be prevented from being spoiled or altered.
[0032]
The case where the signal which detected the water level fall of the rough separation tank 71 by the rough separation tank water level detection means 84 was transmitted to the measurement control means 4 is demonstrated. In this case, the flow rate of the water intake means 70 is reduced. Therefore, the measurement control unit 4 increases the flow rate of the water intake unit 70 by a predetermined amount. The water level of the rough separation tank 71 is detected again after a predetermined time. If the water level has not recovered, the measurement control means 4 further increases the flow rate of the water intake means 70 by a predetermined amount. When the flow rate of the water intake means 70 reaches the maximum value, the water intake means 70 is regarded as abnormal, and the same measures are taken as when an abnormality occurs in the water intake means 70 described above.
[0033]
Next, the case where the filtrate tank water level detection means 85 transmits a signal that detects a drop in the water level of the filtrate tank 77 to the measurement control means 4 will be described. In this case, this is because the filtration flow rate of the membrane separation device 74 is reduced. The measurement control means 4 increases the flow rate of the coarse separation liquid supply means 73 by a predetermined amount. After a predetermined time, the water level in the filtrate tank 77 is detected again. If the water level has not recovered, the measurement control means 4 increases the flow rate of the coarse separation liquid supply means 73 by a predetermined amount. When the flow rate of the coarse separation liquid supply unit 73 reaches the maximum value, the flow rate of the filtration unit 76 is increased by a predetermined amount. After a predetermined time, the water level in the filtrate tank 77 is detected again. When the water level has not recovered, the measurement control unit 4 increases the flow rate of the filtering unit 76 by a predetermined amount. When the flow rate of the filtration means 76 reaches the maximum value, the measurement control means 4 determines that the membrane of the membrane separation device 74 has deteriorated, and notifies the operation manager of the membrane cleaning or replacement. As described above, by providing the abnormality detection means to each of the plurality of facilities and the measurement target liquid supply means on the downstream side of the switching device, a failure location determination function can be added and maintenance management can be facilitated.
[0034]
The means for increasing the filtration flow rate flowing through the membrane separation device 74 includes a membrane separation device.
There are a method for increasing the supply pressure to 74 and a method for increasing the suction pressure. In order to increase the supply pressure, the coarse separation liquid supply means installed upstream of the membrane separation device 74
The flow rate of 73 is increased. In order to increase the suction pressure, the flow rate of the filtering means 76 installed on the downstream side of the membrane separation device 74 is increased. As described above, as means for increasing the filtration flow rate, there is a method of increasing the flow rate of the coarse separation crude liquid supply means 73 or the filtration means 76, but the measurement control means 4 gives priority to the flow increase in the coarse separation liquid supply means 73. . This is because the flow of the coarse separation liquid has an effect of cleaning the filtration membrane surface in the membrane separation device 74.
[0035]
(Fifth embodiment)
FIG. 6 shows another embodiment of the water quality measurement system to which the present invention is applied. The difference from the third embodiment is the presence or absence of the filtering means 76 in the flow path 112a. The filtrate is obtained on the downstream side of the membrane separation device 74 because the pressure difference between the supply side (upstream side) of the treated water passing through and the filtrate side (downstream side) across the membrane provided in the membrane separation device 74. This is because the filtration proceeds. In the third embodiment, the filtration means 76 is installed so that the filtrate side (downstream side) of the membrane separation device 74 is filtered under a negative pressure. However, in this embodiment, the filtrate side (downstream side) of the membrane separation device 74 is opened to the atmospheric pressure, and the supply pressure of the coarse separation solution supply means 73 is utilized to generate a pressure difference across the membrane, Filtering. The supply pressure when the suspension is supplied from the coarse separation liquid supply means 73 is the rough separation liquid supply means.
73, and the diameter and length of the pipe 114 returning from the membrane separation device 74 to the rough separation tank 71. For example, when the amount of filtrate discharged from the membrane separation device 74 decreases, the pipe 114 returning from the membrane separation device 74 to the rough separation tank 71 may be extended. Since the supply pressure of the coarse separation liquid supply means 73 is increased, the pressure difference between the membranes is increased, and the necessary filtrate amount can be secured. By omitting the filtering means 76 according to this embodiment, the equipment cost can be reduced, and the maintenance management of the entire equipment can be facilitated by eliminating the maintenance management of the filtering means 76.
[0036]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the water quality measurement method and the water quality measurement system which can grasp | ascertain the water quality of several points easily, can perform transient judgment of water quality abnormality, or can maintain the quality of treated water.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a water quality measurement system in a first embodiment.
FIG. 2 is a configuration diagram of a water quality measurement system in a second embodiment.
FIG. 3 is a configuration diagram of a water quality measurement system in a third embodiment.
FIG. 4 is a flowchart showing an operation method of a water quality measurement system in a third embodiment.
FIG. 5 is a configuration diagram of a water quality measurement system according to a fourth embodiment.
FIG. 6 is a configuration diagram of a water quality measurement system in a fifth embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Switching apparatus, 2 ... Solid-liquid separator, 3 ... Measuring instrument, 4 ... Measurement control means, 5 ... Biological reaction tank, 6 ... Sedimentation basin, 11, 12, 13, 14, 15 ... Switching valve, 51 ... Anaerobic Tank, 52 ... anoxic tank, 53 ... aerobic tank, 70 ... water intake means, 71 ... coarse separation tank, 72, 75, 78 ... discharge means, 73 ... coarse separation liquid supply means, 74 ... membrane separation device, 76 ... Filtration means, 77 ... Filtrate tank, 80 ... Water intake means abnormality detection means, 81 ... Coarse separation liquid supply means abnormality detection means, 82 ... Membrane separation apparatus abnormality detection means, 83 ... Filtration means abnormality detection means, 84 ... Coarse separation tank Water level detection means, 85 ... filtrate tank water level detection means, 90 ... drainage process, 91 ... water intake process, 92 ... coarse separation tank storage process, 93 ... filtrate tank storage process.

Claims

Provide water intake means at multiple points in the flow path through which the liquid to be measured flows from the upstream side to the downstream side in the sewage treatment plant,
Measure the water quality of the measurement target liquid taken by a water intake means provided at an arbitrary point,
A water quality measurement method for switching the water intake means based on the measured water quality results,
Water intake upstream or downstream from the water intake means at the arbitrary point when the measured value of the liquid to be measured taken from the water intake means provided at an arbitrary point exceeds the set upper limit value or falls below the lower limit value A water quality measurement method, characterized in that the water quality of a measurement target liquid taken from the switched water intake means is measured.

Water intake means provided at a plurality of points in the flow path through which the liquid to be measured flows from the upstream side toward the downstream side in the sewage treatment plant,
A switching device for switching the water intake means provided at a plurality of points;
A measuring instrument for measuring the quality of the liquid to be measured taken by the water intake means;
A water quality measurement system comprising measurement control means for controlling the switching device based on the measured water quality result,
Water intake upstream or downstream from the water intake means at the arbitrary point when the measured value of the liquid to be measured taken from the water intake means provided at an arbitrary point exceeds the set upper limit value or falls below the lower limit value A water quality measurement system comprising: means for switching to the means; and means for measuring the water quality of the measurement target liquid taken from the switched water intake means.

Install multiple flow paths in the sewage treatment plant through which the liquid to be measured flows from upstream to downstream,
The flow path joins one flow path on the downstream side,
Provide water intake means at multiple points in any flow path,
Measure the water quality of the measurement target liquid taken by the water intake means,
A water quality measurement method for switching the water intake means based on the measured water quality results,
Installing water intake means on the downstream side of the plurality of flow paths and the merged flow path,
When the measured value of the liquid to be measured taken by the water intake means installed in the joined flow path exceeds the set upper limit value or falls below the lower limit value,
A water quality measurement method characterized by measuring the water quality of a measurement target liquid taken from a water intake means provided on the downstream side of the plurality of flow paths.

The water quality measurement system according to claim 2,
A water quality measurement system comprising a plurality of facilities for filtering the liquid to be measured between the switching device and the measuring instrument, each of which has a discharging means.

The water quality measurement system according to claim 4,
The plurality of facilities and the measurement target liquid supply means are alternately arranged on the flow path through which the measurement target liquid flows from the switching device toward the measuring instrument,
A flow path is provided between the plurality of facilities,
At least one of the plurality of facilities and the measurement target liquid supply unit includes an abnormality detection unit.