JP2004351326A

JP2004351326A - Water quality monitoring system

Info

Publication number: JP2004351326A
Application number: JP2003152303A
Authority: JP
Inventors: Norimitsu Abe; 法光阿部; Seiichi Murayama; 清一村山; Kyotaro Iyasu; 巨太郎居安; Shojiro Tamaki; 省二郎環
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2003-05-29
Filing date: 2003-05-29
Publication date: 2004-12-16
Anticipated expiration: 2023-05-29
Also published as: JP4145717B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water quality monitoring system which monitors and controls water quality in the water cleaning process so as to properly keep a disinfection by-product concentration and a chlorine concentration at the outlet of a water cleaning plant even when the concentration of dissolved organic substance included in raw water in the water cleaning plant is high, by appropriately controlling the charging of activated carbon which adsorbs and removes the organic substance soluble and included in the raw water in the water cleaning plant, and the charging of chlorine . <P>SOLUTION: Fluorescent intensity of the raw water flowing into a splashdown well 1 in the water cleaning plant is measured by a fluorescent analyzer 22 and the concentration of the organic soluble substance is estimated from the measurement result. Therefore, the charging amount of activated carbon which removes the organic soluble substance can be properly controlled, the production amount of the disinfection by-product is suppressed low and, moreover, the rate of chlorine charging can be properly controlled so as to maintain a predetermined residual chlorine concentration. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、消毒副生成物濃度と塩素濃度の分布予測に基づき浄水場内や水道供給管路網内の消毒副生成物濃度および塩素濃度が目標値を満たすように制御する水質監視制御システムに関する。
【０００２】
【従来の技術】
浄水場では、地下水や表流水を原水として着水井に導入し、凝集沈殿設備において凝集剤を添加してフロックを形成することにより沈殿処理を実施する。その後、上澄み液を砂ろ過装置に通して懸濁物を除去し、最後に消毒用の塩素処理を施して水道水供給管路網により需要家に供給している。このように、水道水供給管網末端の需要家における残留塩素濃度が適正になるように制御を行なっており、これらの技術に関する提案もなされている（例えば、特許文献１参照）。
【０００３】
浄水場では、消毒用塩素処理の効果をより確実にするため、凝集剤注入点以前に塩素を注入する前塩素処理や、沈殿水に塩素を注入する中間塩素処理が行われている。前塩素処理では、原水中のアンモニア性窒素や微生物の除去、あるいは鉄およびマンガンの酸化除去のために有効である。これに対し、消毒副生成物、例えばトリハロメタン、ジクロロ酢酸、ハロ酢酸の前駆物質である溶存性有機物が多い原水に対しては、消毒副生成物低減のため、中間塩素処理を採用することが望ましい。
【０００４】
個々の塩素処理の切り替えは、自動制御ではなく原水水質を監視しながらオペレ−タが勘と経験に頼り操作している。
【０００５】
また、原水水質が悪化し通常処理で処理しきれない時は、着水井などに粉末の活性炭を投入し、溶存性有機物を粉末活性炭に吸着させ、その後の凝集沈殿処理で除去している。粉末活性炭の注入量も自動制御ではなく、原水水質を監視しながらオペレータが勘と経験を頼りに決定しているのが実情である。
【０００６】
ところで、浄水処理においては、上述のように消毒処理や鉄・マンガン除去等のため塩素処理が広く使用されている。しかし、原水に消毒副生成物の前駆物質である溶存性有機物が多く含まれている場合、塩素処理によって消毒副生成物が生成する。消毒副生成物は発ガン性物質であるため、浄水工程において消毒副生成物の生成を抑制する必要がある。
【０００７】
現在、消毒副生成物と溶存性有機物の測定には時間と費用を要するため、オンラインでモニタリングすることは不可能である。溶存性有機物除去に効果のある処理方法としては、オゾン処理と生物活性炭の組み合わせ処理等の高度浄水処理があるが、オゾン処理と生物活性炭の組み合わせ処理装置を有している浄水場は少なく実用的でない。
【０００８】
【特許文献１】
文献名：特開平１０−１３７７６４号公報
【０００９】
【発明が解決しようとする課題】
このように浄水場に流入する原水に溶存性有機物質が多く含まれていると、塩素と反応し消毒副生成物が生じるので、この溶存性遊戯物質を粉末の活性炭に吸着させて減少させる必要がある。
【００１０】
本発明の目的は、浄水場原水に含まれる溶存性有機物を吸着除去する活性炭注入量と、塩素注入制御とを適切に制御することにより、浄水場原水に含まれる溶存性有機物質濃度が高い場合にも、浄水場出口での消毒副生成濃度及び塩素濃度とを適正に保つように、浄水工程の水質を監視し、制御する水質監視制御システムを提供することにある。
【００１１】
【課題を解決するための手段】
本発明による水質監視制御システムは、浄水場に流入する原水の蛍光強度を測定する蛍光強度測定手段、前記原水の流量を測定する原水流量測定手段、前記原水の水温測定手段及び前記原水の水質を測定する原水水質測定手段と、測定された原水の蛍光強度と溶存性有機物質濃度との相関関係を表す演算式により原水内溶存性有機物質濃度を求める原水内溶存性有機物質濃度演算手段と、処理水の溶存性有機物質濃度目標値と原水の水温、原水水質測定手段により測定されたｐＨ及び浄水場内での塩素注入点に基づく塩素処理時間に基づき浄水場内の消毒副生成物濃度予測値を求める演算式により、浄水場内の消毒副生成物濃度予測値が予め設定した値以下となる処理水の溶存性有機物質濃度目標値を求める処理水溶存性有機物質濃度目標値演算手段と、この求められた処理水溶存性有機物質濃度目標値と前記原水内溶存性有機物質濃度との差と前記原水流量により導出される粉末活性炭処理時間とを用いて原水への活性炭注入率を求める活性炭注入率演算手段とを備えたことを特徴とする。
【００１２】
この場合、浄水場内の浄水工程によって減少する溶存性有機物質濃度の総和を、処理水溶存性有機物濃度目標値から差し引いて活性炭注入率を補正演算するとよい。
【００１３】
この浄水工程によって減少する溶存性有機物質濃度は、凝集沈殿池工程及びろ過池工程による溶存性有機物質除去量と、塩素との反応による消毒副生成物への変換量である。
【００１４】
また、本発明の水質監視制御システムは、原水水質測定手段により測定された塩素要求量及びアンモニア濃度から塩素消費量を予測する塩素消費量予測手段と、前記浄水場での消毒による塩素消費量を予測する消毒塩素消費量予測手段と、活性炭注入処理後に残留した溶存性有機物質と塩素との反応による消毒副生成物変換塩素消費量を予測する消毒副生成物変換塩素消費量予測手段と、予め設定された浄水場出口における塩素濃度目標値と、前記塩素消費量、消毒塩素消費量、消毒副生成物変換塩素消費量とから塩素注入率を求める塩素注入率演算手段とを備えていてもよい。
【００１５】
また、本発明の水質監視制御システムは、浄水場が管轄する水道管路網の管径、管路長、材質、管同士の接続関係、水圧、需要パターン予測結果に基づいて、水道管路網上の任意の２点間の水道水流下時間を予測する流下時間予測手段と、この流下時間予測手段により求められる塩素注入点から水道管網上の任意の点までの水道水流下速度予測値と、前記浄水場出口の残留塩素濃度、水道水の水温、水道管の材質情報とを用い、下流に位置する側での残留塩素濃度減少率を演算導出する残留塩素濃度減少率予測手段と、この残留塩素濃度減少率予測手段による予測結果に基づいて、任意の予測点における残留濃度を演算導出する残留塩素濃度予測手段とを備え、この残留塩素濃度予測手段で求められる水道配管網の末端地点での残留塩素濃度が予め設定された最小残留塩素濃度未満にならないように浄水場出口での残留塩素濃度を設定して塩素注入率を求めてもよい。
【００１６】
この場合、残留塩素濃度予測手段で求められる水道配管網の末端地点での残留塩素濃度が予め設定された最小残留塩素濃度未満にならないように浄水場出口での溶存性有機物質濃度を減少させるに必要な活性炭注入量を演算し、原水への活性炭注入量を補正するとよい。
【００１７】
本発明の水質監視制御システムは、原水の蛍光強度と水温の少なくとも一方が予め設定された値より大きい場合は塩素注入点を凝集沈殿後の中間塩素注入点とし、前記両値が前記設定値より小さい場合は、凝集沈殿前の前塩素注入点とする塩素注入点制御手段を設けてもよい。
【００１８】
また、本発明の水質監視制御システムは、浄水場での浄水処理工程で生成される消毒副生成物量と、浄水場出口での溶存性有機物質量により水道管網内の残留塩素と反応して生成される消毒副生成物量との総和が、予め設定された水道供給末端部での消毒副生成物濃度より大きくならないように、浄水場出口の溶存性有機物質濃度を減少させるに必要な活性炭注入量を演算し、この演算結果に従って活性炭注入装置を制御するとよい。
【００１９】
さらに、本発明の水質監視制御システムは、浄水場から送出される浄水の蛍光強度を測定する蛍光分析計を設け、この蛍光分析計の測定値から、浄水内に残留する溶存性有機物質濃度を推定するようにしてもよい。
【００２０】
これらの発明では、浄水場内に流入する原水の蛍光強度を蛍光分析計により測定し、その測定結果から溶存性有機物質濃度を推定しているので、これを除去する活性炭の注入量を適切に制御でき、かつ消毒副生成物の生成量を低く抑え、しかも所定の残留塩素濃度を維持できるように塩素注入率を適切に制御することができる。
【００２１】
【発明の実施の形態】
以下、本発明による水質監視制御システムの一実施の形態を図面を参照して詳細に説明する。
【００２２】
図１は、一実施の形態の全体構成を示している。図において、１は浄水場の着水井で、原水はこの着水井１へ流入する。着水井１には、急速攪拌池２、フロック形成池４及び沈殿池５からなる凝集沈殿設備が接続されている。着水井１を出た処理水は、凝集沈殿設備を構成する急速撹拌池２へ流入する。急速撹拌池２の入口では、図示していない凝集剤注入装置により原水に凝集剤が注入され、フラッシュミキサ３により急速撹拌される。原水と凝集剤とを攪拌した処理水は、次にフロック形成池４に入る。フロック形成池４では処理水にフロックが成長し、次段の沈澱池５にて成長したフロックの多くが沈殿除去される。
【００２３】
沈殿池５の後段にはろ過池６と浄水池７が順次接続されている。沈澱池５で多くのフロックが沈殿除去された処理水は、沈殿池５から流出し、その流出水はろ過池６でろ過され、浄水として浄水池７に貯えられる。
【００２４】
ここで、前記着水井１では、後述するように、原水の溶存性有機物質を吸着除去するために、活性炭注入装置１０により粉末の活性炭が注入される。また、消毒用の塩素として、次亜塩素酸ナトリウム溶液或いは二酸化塩等の塩素剤が、塩素注入装置１１により、塩素注入点制御装置１２を介して浄水工程に注入される。この場合、塩素注入点は、凝集沈殿前の着水井１（前塩素注入点）及びろ過池６の入口（中間塩素注入点）のいずれかと、浄水池７とである。
【００２５】
ここで、着水井１へ注入される塩素剤は前塩素処理として、ろ過池６の入口に注入される塩素剤は中間塩素処理として注入される。前塩素処理と中間塩素処理の切り替えは、塩素注入点制御装置１２によって制御される。また、浄水池７に注入される塩素剤は、後塩素として浄水場出口での残留塩素濃度を調整する為に注入される。なお、前塩素処理と中間塩素処理の切り替え条件は後述する。
【００２６】
浄水池７に貯えられた処理水（浄水）は、送水ポンプ８によって、水道水供給管路網９を通って各需要家へと供給される。
【００２７】
前記着水井１の入口配管には、流量計２０、温度計２１が設置されている。さらに、原水入口配管からは、図示しない検水ポンプによって、原水がそれぞれ蛍光分析計２２と、原水水質測定手段２６へと導かれる。この原水水質測定手段２６は、ｐＨ計、塩素要求量計およびアンモニア濃度計から成る。また、浄水池７出口配管には、図示していない検水ポンプを介して残留塩素濃度計２７が連結されており、検水ポンプによって処理水が残留塩素濃度計２７へと導かれる。
【００２８】
水道供給管路網９の各検水点には、水道水流量計２８、水道水温度計２９、水道水圧計３０および水道水残留塩素濃度計３１が設置されている。
【００２９】
次に、制御部のシステム構成について説明する。４０は運転制御手段で、活性炭注入量演算手段５０、塩素注入量率演算手段５１、処理目標値入力手段５３、および処理状況出力手段５４により構成されている。また、この運転制御手段４０には、浄水場内および水道供給管路網９の測定点における水質計器、水温計、流量計および水圧計による測定結果を蓄積する計測値履歴データベース７０と、粉末活性炭注入装置１０や塩素注入装置１１および塩素注入点制御装置１２の制御履歴を蓄積する制御履歴データベース７１とが接続されている。
【００３０】
４１は残留塩素濃度予測手段で、水道需要予測手段６０、流下時間予測手段６１および残留塩素濃度減衰予測手段６２を有する。この残留塩素濃度予測手段４１には、水道水の需要履歴を蓄積する需要履歴データベース８０と、水道供給管路網の管径、管路長、材質、管同士の接続関係を保存する管路網データベース８１と、水道供給管路網の計測点に設置された水道水流量計２８、水道水温度計２９、水道水圧計３０および水道水残留塩素濃度計３１による測定データを情報を収集する管路網内計器情報収集手段８２が接続されている。
【００３１】
上記構成において、活性炭注入量演算手段５０は、原水流入配管に設けられた各種測定手段からの各種測定値や処理目標値入力手段５３により設定された目標値などを入力し、粉末活性炭の注入率を演算導出し、その演算結果により活性炭注入装置１０を動作させる。この活性炭注入率演算手段５０における演算手順を図２により説明する。
【００３２】
図２において、目標設定行程１００は、粉末活性炭処理後の溶存性有機物質濃度の目標値初期値を設定する行程であり、処理目標値入力手段５３より入力された値に設定される。この設定値は、処理目標値入力手段５３により変更された時だけ更新される。
【００３３】
次に、溶存性有機物質濃度推定行程１０１では、蛍光分析計２２により計測された蛍光強度ＦＬ_ｉと溶存性有機物質濃度の相関特性を表す式（１）により、原水内の溶存性有機物質濃度Ｃ_{（ＮＯＭ）ｉ}を演算する。
【００３４】
【数１】

ここで、
Ｃ_{（ＮＯＭ）ｉ}：原水内の溶存性有機物質濃度
ＦＬ_ｉ：原水の蛍光強度
ｋ_０：定数
ｋ_１：係数
粉末活性炭注入率初期値演算行程１０２では、目標設定行程１００で設定された処理水の溶存性有機物質濃度Ｃ_{（ＮＯＭ）０}と、溶存性有機物質濃度推定行程１０１で演算導出された原水内の溶存性有機物質濃度Ｃ_{（ＮＯＭ）ｉ}と、流量計２０によって計測された原水流量と着水井１の容積の関係から演算導出される粉末活性炭処理時間ｔ_１を用いて、式（２）により、原水内の溶解性有機物質を吸着除去する為に必要な粉末活性炭注入率初期値ＡＣ_０を演算する。
【００３５】
【数２】

ここで、
ＡＣ_０：粉末活性炭注入率初期値
Ｃ_{（ＮＯＭ）ｉ} ：原水内の溶存性有機物質濃度
Ｃ_{（ＮＯＭ）０} ：処理水の溶存性有機物質濃度目標値
ｔ_１：粉末活性炭処理時間
ｍ：処理時間の指数
ｎ：指数
ｋ_ａｃ１〜ｋ_ａｃ４：係数
消毒副生成物生成濃度予測行程１０３では、温度計２１による測定値Ｔ_ｗと、原水水質測定手段２６によって測定されたｐＨ値２３、塩素注入点制御装置１２により決定された塩素注入点の制御情報（前塩素処理か中間塩素処理か）により演算される塩素処理時間ｔ_ｃｌに基づいて浄水場出口での消毒副生成物濃度Ｃ_{（ＤＳＰ）} _ｃｗ _ｉを式（３）により演算する。
【００３６】
【数３】

ここで、
Ｃ_{（ＤＳＰ）} _ｃｗ _ｉ：浄水内の消毒副生成物濃度予測値
Ｃ_{（ＮＯＭ）０} ：処理水の溶存性有機物質濃度目標値
Ｔ_ｗ：水温
ｐＨ：ｐＨ計測定値
ｔ_ｃｌ：塩素処理時間
ａ：ｐＨの指数
ｋ_{ＤＳＰ１，}ｋ_ＤＳＰ２：係数
次に、式（３）の演算結果が、処理目標値入力手段５３により設定された浄水出口での消毒副生成物濃度設定値以下になるような処理水の溶存性有機物質濃度目標値Ｃ_{（ＮＯＭ）０}を、上記式（３）に基づく式（４）により求める。
【００３７】
【数４】

ここで、
Ｃ_{（ＤＳＰ）} _ｃｗ _ｉ：浄水内の消毒副生成物濃度予測値
Ｃ_{（ＮＯＭ）０} ：処理水の溶存性有機物質濃度目標値
Ｔ_ｗ：水温
ｐＨ：ｐＨ計測定値
ｔ_ｃｌ：塩素処理時間
ａ：ｐＨの指数
ｋ_{ＤＳＰ１，}ｋ_ＤＳＰ２：係数
粉末活性炭注入率演算行程１０４では、式（４）で求めた処理水の溶存性有機物質濃度目標値Ｃ_{（ＮＯＭ）Ｏ}を前記式（２）にフィードバックし、式（２）と同じ演算により、溶存性有機物質濃度目標値Ｃ_{（ＮＯＭ）Ｏ}を満足する活性炭注入率ＡＣ_ｍを演算導出する。そして、この演算結果に基づいて粉末活性炭注入装置１０を制御する。
【００３８】
また、この溶存性有機物質濃度は、浄水場内での浄水工程（凝集沈殿工程や、ろ過工程）でも減少するので、この減少分により補正を行なう。すなわち、粉末活性炭注入により吸着されるのは液中の溶存性有機物質であり、濁質中に含まれている溶存性有機物質は、上述した凝集沈殿工程や、ろ過工程により除去される。このため、これらの除去分に相当する溶存性有機物質濃度を原水の溶存性有機物質濃度から差し引いて活性炭注入率を補正する必要がある。さらに、前塩素処理を行なった場合は、塩素処理時間が長くなるため、塩素と反応して消毒副生成物に変換される分が生じる。したがって、消毒副生成物への変換量も溶存性有機物質濃度から差し引いて活性炭注入率を補正する必要がある。
【００３９】
そこで、凝集沈殿池溶存性有機物質除去量演算工程１０５により、凝集沈殿行程で減少する溶存性有機物質濃度を演算し、ろ過池溶存性有機物質除去量演算行程１０６により、ろ過行程で減少する溶存性有機物質濃度を演算する。これらは、別途測定される原水の濁質濃度から容易に演算できる。また、溶存性有機物質の消毒副生成物変換量演算行程１０７で、塩素との反応で消毒副生成物質を生成する過程で減少する溶存性有機物質濃度を演算し（塩素との反応時間から求められる）、それらの総量を差し引くことで活性炭注入量の補正を行なう。
【００４０】
さらに、水道供給管路網９を流れる間に減少する溶存性物質濃度を、溶存性有機物質管路網内減少量演算行程１０８で演算し、この値によっても補正を行なう。すなわち、浄水場出口での溶存性有機物質濃度の高いと、水道供給管路網９を流れる間に水道供給管路網９内の塩素が、溶存性有機物質を消毒副生成物質に変換するために消費されてしまい、予め設定された水道供給管路網末端地点での最小残留塩素濃度を維持できなくなることが考えられる。そこで、溶存性有機物質管路網内減少量演算行程１０８では、残留塩素濃度予測手段４１において、後述するように、水道供給管路網９内の水温と、管路網材質と配管内面接触率と、管路網内流下時間の予測値に基づいて予測される水道供給管路網末端地点での残留塩素濃度が、予め設定された水道供給管路網末端地点での最小残留塩素濃度以下にならないように、浄水場出口での溶存性有機物質濃度を減少させる為に必要な粉末活性炭注入量を演算し、粉末活性炭流入量を補正する。
【００４１】
次に、塩素注入率演算手段５１における演算手順を図３、図４により説明する。図３において目標設定工程２００は、浄水場出口での塩素濃度の目標値の目標値初期値を設定すると共に、水道供給管路網９の末端部での最小残留塩素濃度を設定する行程である。これらの設定は処理目標値入力手段５３より入力され、その設定値は、処理目標値入力手段５３により変更された時だけ更新される。
【００４２】
塩素消費量演算工程２０１では、まず、塩素消費量予測工程２０２において、原水水質測定手段２６による塩素要求量２４およびアンモニア濃度２５の測定値に基づき塩素消費量が予測される。また、原水に対する殺菌により消費される塩素消費量の予測工程２０３が実行される。さらに、消毒副生成物変換による塩素消費量の予測工程２０４が実行される。この消毒副生成物変換による塩素消費量は、蛍光分析計２２により測定された原水の蛍光強度、流量計２９により計測された原水流量、温度計２１により計測された原水水温から原水中の溶存性有機物質濃度が求められ、この溶存性有機物質濃度と塩素処理時間予測工程からの塩素処理時間とから消毒副生物変換塩素消費量が予測演算される。
【００４３】
これらによって求められた塩素消費量と、目標値設定工程２００で設定された浄水場出口での残留塩素濃度との総和に基づいて、塩素剤の注入率を演算され、この演算結果に基づいて、図１で示した塩素注入装置１１が制御される。
【００４４】
ここで、塩素を、凝集剤注入点以前に注入する前塩素処理にするか、沈殿水に対して注入する中間塩素処理にするかは次の条件によって決定する。すなわち、原水の蛍光強度と水温の少なくとも一方が予め設定された値より大きい場合は塩素注入点を凝集沈殿後の沈殿水に対する中間塩素処理とし、前記両値が前記設定値より小さい場合は、凝集沈殿前の前塩素注入処理とするように塩素注入点制御手段１２で切り替える。
【００４５】
すなわち、溶存性有機物質が多い原水に対しては、塩素との反応により生成される消毒副生成物（例えばトリハロメタン、ジクロロ酢酸、ハロ酢酸）低減のため、塩素処理時間が短くなる中間塩素処理を採用する。また、水温が高くなると、消毒副生成物が生成しやすくなるので、やはり塩素処理時間が短くなる中間塩素処理を採用する。これに対し、原水の溶存性有機物が少ない場合や水温が低い場合は、原水中のアンモニア性窒素や微生物の除去、あるいは鉄およびマンガンの酸化除去のために有効である前塩素処理を用いる。
【００４６】
図４は、塩素注入率を補正する手順を示す工程図である。図４の塩素注入量補正工程では、先ず、浄水場出口での溶存性有機物質濃度の予測工程２０７が実行される。次に、残留塩素濃度予測行程２０８によって、水道供給管路網末端地点での残留塩素濃度が予測演算される。この残留塩素濃度の予測は、水道供給管路網９の各計測点に設置された水道水流量計２８、水道水温度計２９、水道水圧計３０および水道水残留塩素濃度計３１による測定値と、管路網データベース８１に保存されている水道供給管路網９の管径、管路長、材質、管同士の接続関係の各データと、水道需要予測手段６０によって予測された水道需要量予測値に基づいて、水道水供給管路網での残留塩素濃度を予測する。
【００４７】
すなわち、浄水場が管轄する水道管路網９の管径、管路長、材質、管同士の接続関係、水圧、需要パターン予測結果に基づいて、流下時間予測手段６１により水道管路網９上の任意の２点間の水道水流下時間を予測する。次に、この流下時間予測手段により求められる、塩素注入点（浄水池７）から水道管網９上の任意の点までの水道水流下速度予測値と、前記塩素注入点近くの浄水場出口の残留塩素濃度、水道水の水温、水道管の材質情報とを用い、残留塩素濃度減少率予測手段６２により下流に位置する側での残留塩素濃度減少率を演算導出する。この残留塩素濃度減少率予測手段６２による予測結果に基づいて、水道供給管路網末端部残念演算工程２０６において、残留塩素濃度予測手段４１により任意の予測点（ここでは水道供給管路網末端地点）における残留塩素濃度を演算導出する。
【００４８】
このようにして求めた水道供給管路網末端地点の残留塩素濃度を予測値とし、目標設定行程２００によって予め設定された水道供給管路網末端部での最小残留塩素濃度を目標値として比較行程２０８で比較する。そして、予測値と目標値の差により、図３で示した塩素注入率演算行程２０１の演算値を補正する。
【００４９】
この結果、水道供給管路網９の末端における残留塩素濃度を、予め設定した最小値を下回ることなく適切に維持することができる。
【００５０】
次に、図５で示す実施の形態を説明する。図５において、図１と同一部分には同一符号を付して詳細な説明を省略する。
【００５１】
この実施の形態では、浄水池７に蛍光分析計３５を設置し、浄水池（浄水場出口でもある）の浄水の溶存性有機物質濃度を演算し、推定している。活性炭注入率演算手段５０及び塩素注入率演算手段では、上述した蛍光分析計３５の計測結果に基づく溶存性有機物質濃度推定値と、図１の実施の形態と同様の手法で予測した浄水場出口での溶存性有機物質濃度予測値とを比較し、これら両者の差に基づいて、粉末活性炭注入率演算式と、塩素注入率演算式を補正する。この結果、粉末活性炭注入制御精度と塩素注入制御を共に向上させることができる。
【００５２】
【発明の効果】
本発明によれば、浄水場原水に含まれる消毒副生成物の前駆物質である溶存性有機物を吸着除去する活性炭注入量制御と、塩素注入と関連つけて行なうことにより、浄水場原水の溶存性有機物質濃度が高い場合にも、浄水場出口での消毒副生成濃度と、塩素濃度と、水道管路網内の残留塩素濃度および消毒副生成物濃度の目標値を満たすように、浄水工程の水質を監視し、制御することができ、安全で、美味しい水道水を供給することができる。
【図面の簡単な説明】
【図１】本発明による水質監視制御システムの一実施の形態を示すシステムブロック図である。
【図２】同上一実施の形態における活性炭注入量演算手段の演算過程を説明するフローチャートである。
【図３】同上一実施の形態における塩素注入率演算手段の演算過程を示すフローチャートである。
【図４】同上一実施の形態における塩素注入率の補正過程を説明するフローチャートである。
【図５】本発明の他の実施の形態を示すシステムブロック図である。
【符号の説明】
１着水井
２，３，４，５凝集沈殿設備
６ろ過池
７浄水池
９水道供給管路網
１０活性炭注入装置
１１塩素注入制御装置
１２塩素注入点制御装置
２０原水流量計
２１原水温度計
２６原水水質測定手段
４１残留塩素濃度予測手段
５０活性炭注入率演算手段
５１塩素注入率演算手段
６０水道需要予測手段
６１流下時間予測手段
６２残留塩素濃度減少率予測手段[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a water quality monitoring and control system that controls a concentration of a disinfection by-product and a concentration of chlorine in a water purification plant and a network of water supply pipes to meet target values based on a distribution prediction of the concentration of the disinfection by-product and the concentration of chlorine.
[0002]
[Prior art]
In the water treatment plant, groundwater or surface water is introduced into the landing well as raw water, and flocculation is performed by adding a flocculant in a flocculation and sedimentation facility to perform flocculation treatment. Thereafter, the supernatant liquid is passed through a sand filtration device to remove suspended matter, and finally subjected to chlorination treatment for disinfection and supplied to consumers through a tap water supply network. As described above, control is performed so that the residual chlorine concentration in the consumer at the end of the tap water supply pipe network becomes appropriate, and proposals regarding these technologies have been made (for example, see Patent Document 1).
[0003]
In the water treatment plant, in order to further ensure the effect of chlorination for disinfection, pre-chlorination before injecting chlorine before the coagulant injection point and intermediate chlorination for injecting chlorine into settling water are performed. Prechlorination is effective for removing ammonia nitrogen and microorganisms in raw water, or for oxidizing and removing iron and manganese. On the other hand, for raw water having a large amount of dissolved organic substances which are precursors of disinfection by-products, for example, trihalomethane, dichloroacetic acid, and haloacetic acid, it is desirable to employ an intermediate chlorination treatment to reduce disinfection by-products. .
[0004]
Switching of individual chlorination is not automatic control, but is performed by the operator depending on intuition and experience while monitoring raw water quality.
[0005]
In addition, when the quality of the raw water deteriorates and cannot be completely treated by the ordinary treatment, powdered activated carbon is put into a landing well or the like, and the dissolved organic matter is adsorbed on the powdered activated carbon, and is removed by the subsequent coagulation sedimentation treatment. The actual situation is that the injection amount of powdered activated carbon is not automatically controlled but is determined by the operator based on intuition and experience while monitoring the quality of raw water.
[0006]
By the way, in water purification treatment, chlorination is widely used for disinfection treatment and iron / manganese removal as described above. However, when the raw water contains a large amount of dissolved organic matter which is a precursor of the disinfection by-product, the disinfection by-product is generated by the chlorination. Since disinfection by-products are carcinogenic substances, it is necessary to suppress the generation of disinfection by-products in the water purification process.
[0007]
Currently, measuring disinfection by-products and dissolved organics is time-consuming and expensive, and cannot be monitored online. As a treatment method effective for removing dissolved organic substances, there is an advanced water purification treatment such as a combination treatment of ozone treatment and biological activated carbon, but few water purification plants have a combined treatment device of ozone treatment and biological activated carbon, which is practical. Not.
[0008]
[Patent Document 1]
Document name: Japanese Patent Application Laid-Open No. Hei 10-137768
[Problems to be solved by the invention]
If the raw water flowing into the water treatment plant contains a large amount of dissolved organic substances, it reacts with chlorine to produce disinfection by-products. There is.
[0010]
An object of the present invention is to control the injection amount of activated carbon for adsorbing and removing dissolved organic substances contained in raw water of a water purification plant and the chlorine injection control appropriately, so that the concentration of dissolved organic substances contained in the raw water of the water purification plant is high. Another object of the present invention is to provide a water quality monitoring and control system for monitoring and controlling the water quality in a water purification process so as to appropriately maintain the concentration of by-product disinfection and the concentration of chlorine at the outlet of the water purification plant.
[0011]
[Means for Solving the Problems]
The water quality monitoring and control system according to the present invention includes: a fluorescence intensity measurement unit that measures a fluorescence intensity of raw water flowing into a water purification plant; a raw water flow measurement unit that measures a flow rate of the raw water; a water temperature measurement unit that measures the raw water temperature; and a water quality of the raw water. Raw water quality measurement means to measure, the dissolved organic substance concentration in raw water to calculate the dissolved organic substance concentration in raw water by an arithmetic expression representing the correlation between the measured fluorescence intensity of the raw water and the dissolved organic substance concentration, Based on the target value of the dissolved organic substance concentration of the treated water, the temperature of the raw water, the pH measured by the raw water quality measuring means, and the estimated concentration of disinfection by-products in the water purification plant based on the chlorination time based on the chlorine injection point in the water purification plant. The target value for the concentration of the dissolved organic substance in the treated water is calculated so that the predicted value of the concentration of the disinfection by-product in the water purification plant is equal to or less than a preset value. Calculating means, and injecting activated carbon into raw water using the difference between the determined target value of the dissolved organic substance concentration of treated water and the concentration of dissolved organic substance in raw water, and the activated carbon powder processing time derived from the flow rate of raw water. Activated carbon injection rate calculating means for determining the rate.
[0012]
In this case, the sum of the dissolved organic substance concentration reduced by the water purification process in the water purification plant may be subtracted from the target value of the treated water soluble organic substance concentration to correct the activated carbon injection rate.
[0013]
The dissolved organic substance concentration reduced by this water purification step is the amount of dissolved organic substance removed by the coagulation sedimentation tank step and the filtration tank step and the amount of conversion to the disinfection by-product due to the reaction with chlorine.
[0014]
Further, the water quality monitoring and control system of the present invention comprises: a chlorine consumption predicting means for predicting a chlorine consumption based on the chlorine demand and the ammonia concentration measured by the raw water quality measuring means; and a chlorine consumption by disinfection at the water purification plant. Disinfection by-product conversion chlorine consumption prediction means for predicting disinfection chlorine consumption prediction means for predicting, and disinfection by-product conversion chlorine consumption prediction means for predicting the disinfection by-product conversion chlorine consumption due to the reaction between the dissolved organic substance remaining after activated carbon injection treatment and chlorine. The apparatus may further include a chlorine injection rate calculating means for calculating a chlorine injection rate from the set chlorine concentration target value at the outlet of the water purification plant and the chlorine consumption, the disinfecting chlorine consumption, and the disinfecting by-product converted chlorine consumption. .
[0015]
Further, the water quality monitoring and control system of the present invention provides a water pipe network based on a pipe diameter, a pipe length, a material, a connection relationship between pipes, a water pressure, and a demand pattern prediction result of a water pipe network controlled by a water purification plant. A falling time predicting means for predicting a flowing time of tap water between any two points above, a predicted value of a flowing speed of tap water from the chlorine injection point to any point on the water pipe network determined by the flowing time predicting means, Using the residual chlorine concentration at the outlet of the water purification plant, the temperature of the tap water, and the material information of the water pipe, and calculating and calculating the residual chlorine concentration decrease rate on the downstream side; A residual chlorine concentration predicting means for calculating and deriving a residual concentration at an arbitrary prediction point based on the prediction result by the residual chlorine concentration decreasing rate predicting means, at a terminal point of the water pipe network determined by the residual chlorine concentration predicting means. Residual chlorine concentration It may be obtained chlorine injection rate by setting the residual chlorine concentration in the water treatment plant outlet so as not fall below predetermined minimum residual chlorine concentration.
[0016]
In this case, the concentration of dissolved organic substances at the outlet of the water treatment plant should be reduced so that the residual chlorine concentration at the terminal point of the water pipe network determined by the residual chlorine concentration prediction means does not fall below the preset minimum residual chlorine concentration. It is advisable to calculate the required activated carbon injection amount and correct the activated carbon injection amount into the raw water.
[0017]
The water quality monitoring and control system of the present invention, when at least one of the fluorescence intensity and the water temperature of the raw water is larger than a preset value, the chlorine injection point is set as the intermediate chlorine injection point after the coagulation and sedimentation, and the two values are more than the set values. If it is smaller, a chlorine injection point control means may be provided as a pre-chlorine injection point before coagulation and sedimentation.
[0018]
In addition, the water quality monitoring and control system of the present invention reacts with residual chlorine in the water pipe network due to the amount of disinfection by-products generated in the water purification treatment process at the water purification plant and the amount of dissolved organic substances at the outlet of the water purification plant. The amount of activated carbon required to reduce the concentration of dissolved organic substances at the outlet of the water treatment plant so that the sum of the amount of disinfection by-products does not exceed the preset concentration of disinfection by-products at the water supply end. Is calculated, and the activated carbon injection device may be controlled according to the calculation result.
[0019]
Further, the water quality monitoring and control system of the present invention is provided with a fluorescence analyzer for measuring the fluorescence intensity of purified water sent from the water purification plant, and from the measured value of the fluorescence analyzer, the concentration of the dissolved organic substance remaining in the purified water is determined. It may be estimated.
[0020]
In these inventions, the fluorescence intensity of the raw water flowing into the water purification plant is measured by a fluorescence spectrometer, and the concentration of the dissolved organic substance is estimated from the measurement result. Therefore, the injection amount of activated carbon for removing the concentration is appropriately controlled. In addition, the chlorine injection rate can be appropriately controlled so that the amount of disinfection by-products can be reduced and the predetermined residual chlorine concentration can be maintained.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a water quality monitoring and control system according to the present invention will be described in detail with reference to the drawings.
[0022]
FIG. 1 shows an entire configuration of an embodiment. In the figure, reference numeral 1 denotes a landing well of a water purification plant, and raw water flows into the landing well 1. To the landing well 1, a coagulation sedimentation facility including a rapid stirring pond 2, a floc formation pond 4, and a sedimentation pond 5 is connected. The treated water that has left the landing well 1 flows into a rapid stirring pond 2 that constitutes a coagulation sedimentation facility. At the inlet of the rapid stirring pond 2, a flocculant is injected into raw water by a flocculant injection device (not shown), and rapidly stirred by the flash mixer 3. The treated water obtained by stirring the raw water and the flocculant then enters the floc formation pond 4. Floc grows in the treated water in the floc formation pond 4, and most of the flocs grown in the next settling tank 5 are settled and removed.
[0023]
At the subsequent stage of the sedimentation basin 5, a filtration basin 6 and a water purification basin 7 are sequentially connected. The treated water from which many flocs have been settled and removed in the sedimentation basin 5 flows out of the sedimentation basin 5, and the effluent is filtered in the filtration basin 6 and stored in the water purification basin 7 as purified water.
[0024]
Here, in the landing well 1, as described later, powdered activated carbon is injected by an activated carbon injection device 10 in order to adsorb and remove dissolved organic substances in raw water. Further, as chlorine for disinfection, a chlorine agent such as sodium hypochlorite solution or salt dioxide is injected into the water purification step by the chlorine injection device 11 through the chlorine injection point control device 12. In this case, the chlorine injection points are any of the landing well 1 (pre-chlorine injection point) before the coagulation and sedimentation, the entrance of the filtration pond 6 (intermediate chlorine injection point), and the water purification tank 7.
[0025]
Here, the chlorinating agent injected into the landing well 1 is injected as pre-chlorination, and the chlorinating agent injected into the inlet of the filtration pond 6 is injected as intermediate chlorination. Switching between the pre-chlorination and the intermediate chlorination is controlled by the chlorine injection point controller 12. Further, the chlorine agent injected into the water purification tank 7 is injected as post-chlorine to adjust the residual chlorine concentration at the outlet of the water purification plant. The conditions for switching between pre-chlorination and intermediate chlorination will be described later.
[0026]
The treated water (purified water) stored in the water purifier 7 is supplied to each customer by a water supply pump 8 through a tap water supply network 9.
[0027]
A flow meter 20 and a thermometer 21 are installed on the inlet pipe of the landing well 1. Further, raw water is guided from the raw water inlet pipe to the fluorescence analyzer 22 and the raw water quality measuring means 26 by a water pump not shown. The raw water quality measuring means 26 comprises a pH meter, a chlorine demand meter and an ammonia concentration meter. In addition, a residual chlorine concentration meter 27 is connected to the outlet pipe of the water purification tank 7 via a water sample pump (not shown), and the treated water is guided to the residual chlorine concentration meter 27 by the water sample pump.
[0028]
A tap water flow meter 28, a tap water thermometer 29, a tap water pressure gauge 30, and a tap water residual chlorine concentration meter 31 are installed at each water detection point of the tap water supply network 9.
[0029]
Next, the system configuration of the control unit will be described. An operation control means 40 is constituted by activated carbon injection amount calculation means 50, chlorine injection rate calculation means 51, processing target value input means 53, and processing status output means 54. In addition, the operation control means 40 includes a measurement value history database 70 for accumulating the measurement results of the water quality meter, the water temperature meter, the flow meter, and the water pressure gauge at the measurement points in the water purification plant and the water supply pipe network 9; A control history database 71 that accumulates control histories of the device 10, the chlorine injection device 11, and the chlorine injection point control device 12 is connected.
[0030]
Reference numeral 41 denotes a residual chlorine concentration predicting unit, which includes a water demand predicting unit 60, a flowing down time predicting unit 61, and a residual chlorine concentration attenuation predicting unit 62. The residual chlorine concentration predicting means 41 includes a demand history database 80 for accumulating demand history of tap water, and a pipe network for storing pipe diameters, pipe lengths, materials, and connection relationships between pipes of a water supply pipe network. A pipeline for collecting information from a database 81 and data measured by a tap water flow meter 28, a tap water thermometer 29, a tap water pressure gauge 30, and a tap water residual chlorine concentration meter 31 installed at measurement points of a tap water supply pipe network. An in-network instrument information collecting means 82 is connected.
[0031]
In the above configuration, the activated carbon injection amount calculating means 50 inputs various measured values from various measuring means provided in the raw water inflow pipe, the target value set by the processing target value input means 53, and the like, and injects the activated carbon powder injection rate. Is calculated, and the activated carbon injection device 10 is operated based on the calculation result. The calculation procedure in the activated carbon injection rate calculation means 50 will be described with reference to FIG.
[0032]
In FIG. 2, a target setting step 100 is a step of setting a target initial value of the dissolved organic substance concentration after the powdered activated carbon treatment, and is set to a value input from the processing target value input means 53. This set value is updated only when it is changed by the processing target value input means 53.
[0033]
Next, the dissolved organic material concentration estimation step 101, by Equation (1) representing the correlation properties of dissolved organic material concentration and the fluorescence intensity FL _i measured by the fluorometer 22, dissolved organic material concentration in the raw water C _{(NOM) i} is calculated.
[0034]
(Equation 1)

here,
C _{(NOM) i} : concentration of dissolved organic substance in raw water FL _i : fluorescence intensity of raw water k ₀ : constant k ₁ : coefficient powdered activated carbon injection rate initial value calculation step 102, treated water set in target setting step 100 , The dissolved organic substance concentration C _{(NOM) 0} in the raw water, the dissolved organic substance concentration C _{(NOM) i} in the raw water calculated and derived in the dissolved organic substance concentration estimation step 101, and the raw water flow rate measured by the flow meter 20 And the activated carbon treatment time t ₁ calculated from the relationship between the volume of the landing well 1 and the activated powder of activated carbon required to adsorb and remove soluble organic substances in the raw water by the equation (2) using the equation (2). to calculate the AC _0.
[0035]
(Equation 2)

here,
AC ₀ : powder activated carbon injection rate initial value C _{(NOM) i} : dissolved organic substance concentration in raw water C _{(NOM) 0} : dissolved organic substance concentration target value of treated water t ₁ : powdered activated carbon treatment time m: treatment time index n: index _k ac1 _{to k ac4:} factor disinfection in by-product formation concentration prediction step 103, the measured value _{T w} by thermometer 21, raw water quality measuring unit 26 pH value 23 measured by the chlorine injection point control control information chlorine injection point determined by the device 12 (pre-chlorination or intermediate chlorination or) concentration disinfection by-products in the water purification plant outlet based on chlorine treatment time t _cl, which is calculated by C _(DSP) _cw _i Is calculated by Expression (3).
[0036]
[Equation 3]

here,
C _{_(DSP) cw} _i: disinfection by-product concentration predicted value in the water purification _{C (NOM) 0:} Dissolved organic substance concentration target value _{T w} of the treated water: water temperature pH: pH measurement value _{t cl} : Chlorine treatment time a: pH index k _DSP1, k _DSP2 : coefficient Next, the calculation result of the equation (3) is equal to or less than the set value of the concentration of the disinfection by-product at the water purification outlet set by the processing target value input means 53. The dissolved organic substance concentration target value C _{(NOM) 0} of the treated water is calculated by the equation (4) based on the equation (3).
[0037]
(Equation 4)

here,
C _{_(DSP) cw} _i: disinfection by-product concentration predicted value in the water purification _{C (NOM) 0:} Dissolved organic substance concentration target value _{T w} of the treated water: water temperature pH: pH measurement value _{t cl} : Chlorination time a: index of pH k _DSP1, k _DSP2 : coefficient In the powdered activated carbon injection rate calculation step 104, the dissolved organic substance concentration target value C _{(NOM) O} of the treated water obtained by the equation (4) is calculated by the above equation. (2) the feedback, the same operation as in formula (2), calculates and derives the activated carbon infusion rate AC _m satisfying the dissolved organic material concentration target value _{C (NOM) O.} Then, the activated carbon powder injection device 10 is controlled based on the calculation result.
[0038]
In addition, since the concentration of the dissolved organic substance also decreases in the water purification step (coagulation sedimentation step or filtration step) in the water purification plant, correction is made based on the decrease. That is, what is adsorbed by the injection of powdered activated carbon is the dissolved organic substance in the liquid, and the dissolved organic substance contained in the suspended matter is removed by the above-described coagulation-sedimentation step and the filtration step. Therefore, it is necessary to correct the activated carbon injection rate by subtracting the dissolved organic substance concentration corresponding to these removals from the dissolved organic substance concentration of the raw water. Furthermore, when pre-chlorination is performed, the chlorine treatment time becomes longer, and there is a portion that is converted into a disinfection by-product by reacting with chlorine. Therefore, it is necessary to correct the activated carbon injection rate by subtracting the conversion amount to the disinfection by-product from the dissolved organic substance concentration.
[0039]
Therefore, in the coagulation sedimentation tank dissolved organic substance removal amount calculation step 105, the dissolved organic substance concentration that is reduced in the coagulation settling step is calculated, and in the filtration tank dissolved organic substance removal amount calculation step 106, the dissolved organic substance concentration reduced in the filtration step is calculated. Calculate the organic matter concentration. These can be easily calculated from the turbidity concentration of the raw water separately measured. Further, in the disinfection by-product conversion amount calculation step 107 of the dissolved organic substance, the concentration of the dissolved organic substance which is reduced in the process of generating the disinfection by-product by the reaction with chlorine is calculated (calculated from the reaction time with chlorine). ), The amount of activated carbon injected is corrected by subtracting the total amount.
[0040]
Further, the concentration of the dissolved substance that decreases while flowing through the water supply pipeline network 9 is calculated in the dissolved organic substance pipeline network reduction amount calculation step 108, and correction is also performed based on this value. That is, when the concentration of the dissolved organic substance at the outlet of the water purification plant is high, chlorine in the water supply pipe network 9 converts the dissolved organic substance into a disinfection by-product while flowing through the water supply pipe network 9. It is considered that the minimum residual chlorine concentration at the end point of the water supply pipeline network set in advance cannot be maintained. Therefore, in the dissolved organic substance pipe network reduction amount calculation step 108, the residual chlorine concentration prediction means 41 uses the water temperature in the water supply pipe network 9, the pipe network material and the pipe inner surface contact ratio as described later. And the residual chlorine concentration at the end of the water supply pipeline network predicted based on the predicted value of the flow time in the pipeline network falls below the minimum residual chlorine concentration at the preset water supply network end point. In order to avoid this, calculate the amount of powdered activated carbon injected necessary to reduce the concentration of dissolved organic substances at the outlet of the water treatment plant, and correct the amount of powdered activated carbon inflow.
[0041]
Next, the calculation procedure in the chlorine injection rate calculation means 51 will be described with reference to FIGS. In FIG. 3, a target setting step 200 is a step of setting a target initial value of the target value of the chlorine concentration at the outlet of the water purification plant and setting a minimum residual chlorine concentration at the end of the water supply pipeline network 9. . These settings are input from the processing target value input means 53, and the set values are updated only when they are changed by the processing target value input means 53.
[0042]
In the chlorine consumption calculating step 201, first, in a chlorine consumption estimating step 202, the chlorine consumption is predicted based on the measured values of the chlorine demand 24 and the ammonia concentration 25 by the raw water quality measuring means 26. Further, a step 203 of estimating the amount of chlorine consumed by sterilization of the raw water is executed. In addition, a step 204 of estimating chlorine consumption by disinfection by-product conversion is performed. The chlorine consumption due to the conversion of the disinfection by-product is determined by the solubility of the raw water based on the fluorescence intensity of the raw water measured by the fluorescence analyzer 22, the raw water flow rate measured by the flow meter 29, and the raw water temperature measured by the thermometer 21. An organic substance concentration is determined, and a disinfection by-product conversion chlorine consumption is predicted and calculated from the dissolved organic substance concentration and the chlorination time from the chlorination time prediction step.
[0043]
Based on the sum of the chlorine consumption determined by these and the residual chlorine concentration at the water purification plant outlet set in the target value setting step 200, the injection rate of the chlorine agent is calculated, and based on the calculation result, The chlorine injection device 11 shown in FIG. 1 is controlled.
[0044]
Here, whether the chlorine is to be pre-chlorinated before the coagulant injection point or the intermediate chlorination to be injected into the sedimentation water is determined by the following conditions. That is, when at least one of the fluorescence intensity and the water temperature of the raw water is larger than a preset value, the chlorine injection point is treated as an intermediate chlorine treatment for the sedimented water after the coagulation and sedimentation. Switching is performed by the chlorine injection point control means 12 so as to perform the pre-chlorine injection treatment before the precipitation.
[0045]
In other words, for raw water containing a large amount of dissolved organic substances, intermediate chlorination, which shortens the chlorination time, is used to reduce disinfection by-products (eg, trihalomethane, dichloroacetic acid, and haloacetic acid) generated by the reaction with chlorine. adopt. In addition, since the disinfection by-product is likely to be generated when the water temperature is high, the intermediate chlorination, which also shortens the chlorination time, is employed. On the other hand, when the amount of dissolved organic matter in the raw water is low or when the water temperature is low, a pre-chlorination treatment that is effective for removing ammonia nitrogen and microorganisms in the raw water or oxidizing and removing iron and manganese is used.
[0046]
FIG. 4 is a process chart showing a procedure for correcting the chlorine injection rate. In the chlorine injection amount correction step of FIG. 4, first, a step 207 of estimating the dissolved organic substance concentration at the outlet of the water purification plant is executed. Next, the residual chlorine concentration prediction process 208 predicts and calculates the residual chlorine concentration at the terminal point of the water supply pipeline network. The prediction of the residual chlorine concentration is based on the values measured by the tap water flow meter 28, the tap water thermometer 29, the tap water pressure gauge 30, and the tap water residual chlorine concentration meter 31 installed at each measurement point of the tap water supply network 9. , Each data of the pipe diameter, the pipe length, the material, and the connection relation between the pipes of the water supply pipe network 9 stored in the pipe network database 81, and the water demand prediction predicted by the water demand prediction means 60 Based on the values, predict the residual chlorine concentration in the tap water supply network.
[0047]
That is, based on the pipe diameter, the pipe length, the material, the connection relationship between the pipes, the water pressure, and the demand pattern prediction result of the water pipe network 9 controlled by the water purification plant, the flowing-down time prediction means 61 performs the operation on the water pipe network 9. The tap water flow time between any two points in is estimated. Next, the predicted value of the tap water flow velocity from the chlorine injection point (water purification pond 7) to an arbitrary point on the water pipe network 9 obtained by the flow time prediction means, and the water purification plant exit near the chlorine injection point. Using the residual chlorine concentration, the water temperature of the tap water, and the material information of the water pipe, the residual chlorine concentration decrease rate predicting means 62 calculates and derives the residual chlorine concentration decrease rate on the downstream side. Based on the result of the prediction by the residual chlorine concentration reduction rate predicting means 62, in the water supply pipe network terminal area disappointment calculation step 206, the residual chlorine concentration predicting means 41 uses the arbitrary prediction point (here, the water supply pipe network terminal point). Calculate and derive the residual chlorine concentration in).
[0048]
The residual chlorine concentration at the end of the water supply pipeline network obtained in this manner is used as a predicted value, and the minimum residual chlorine concentration at the end of the water supply pipeline network set in advance by the target setting process 200 is set as the target value. Compare at 208. Then, the calculated value of the chlorine injection rate calculation process 201 shown in FIG. 3 is corrected based on the difference between the predicted value and the target value.
[0049]
As a result, the residual chlorine concentration at the end of the water supply pipeline network 9 can be appropriately maintained without falling below a preset minimum value.
[0050]
Next, an embodiment shown in FIG. 5 will be described. 5, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description will be omitted.
[0051]
In this embodiment, the fluorescence analyzer 35 is installed in the water purification tank 7, and the dissolved organic substance concentration of the purified water in the water purification tank (also at the outlet of the water purification plant) is calculated and estimated. In the activated carbon injection rate calculating means 50 and the chlorine injection rate calculating means, the dissolved organic substance concentration estimated value based on the measurement result of the fluorescence analyzer 35 described above and the water purification plant outlet predicted by the same method as the embodiment of FIG. Is compared with the predicted value of the dissolved organic substance concentration, and based on the difference between the two, the formula for calculating the activated carbon powder injection ratio and the calculated chlorine injection ratio are corrected. As a result, both the powder activated carbon injection control accuracy and the chlorine injection control can be improved.
[0052]
【The invention's effect】
According to the present invention, by controlling the injection amount of activated carbon for adsorbing and removing dissolved organic substances that are precursors of disinfection by-products contained in raw water of a water purification plant, and by performing it in association with chlorine injection, the solubility of the water purification plant raw water is improved. Even when the concentration of organic substances is high, the water purification process should be performed so as to meet the target values of disinfection by-product concentration at the outlet of the water treatment plant, chlorine concentration, residual chlorine concentration in the water pipe network, and disinfection by-product concentration. Water quality can be monitored and controlled, and safe and delicious tap water can be supplied.
[Brief description of the drawings]
FIG. 1 is a system block diagram showing one embodiment of a water quality monitoring and control system according to the present invention.
FIG. 2 is a flowchart illustrating a calculation process of an activated carbon injection amount calculation unit in the embodiment.
FIG. 3 is a flowchart showing a calculation process of a chlorine injection rate calculation unit in the embodiment.
FIG. 4 is a flowchart illustrating a process of correcting a chlorine injection rate according to the first embodiment.
FIG. 5 is a system block diagram showing another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Landing well 2, 3, 4, 5 Coagulation sedimentation equipment 6 Filtration pond 7 Purification pond 9 Water supply pipeline network 10 Activated carbon injection device 11 Chlorine injection control device 12 Chlorine injection point control device 20 Raw water flow meter 21 Raw water thermometer 26 Raw water Water quality measuring means 41 Residual chlorine concentration predicting means 50 Activated carbon injection rate calculating means 51 Chlorine injection rate calculating means 60 Water demand forecasting means 61 Flowing time predicting means 62 Residual chlorine concentration decreasing rate predicting means

Claims

Fluorescence intensity measurement means for measuring the fluorescence intensity of the raw water flowing into the water purification plant, raw water flow rate measurement means for measuring the flow rate of the raw water, water temperature measurement means for the raw water quality, and raw water quality measurement means for measuring the quality of the raw water,
A raw water soluble organic substance concentration calculating means for calculating the dissolved organic substance concentration in the raw water by an arithmetic expression representing a correlation between the measured fluorescence intensity of the raw water and the dissolved organic substance concentration,
Based on the target value of the dissolved organic substance concentration of the treated water, the temperature of the raw water, the pH measured by the raw water quality measuring means, and the estimated concentration of disinfection by-products in the water purification plant based on the chlorination time based on the chlorine injection point in the water purification plant. A processing water-soluble organic substance concentration target value calculating means for calculating a target value of the dissolved organic substance concentration of the treated water, in which the predicted value of the concentration of the disinfection by-product in the water purification plant is equal to or less than a preset value,
Activated carbon to determine the activated carbon injection rate into raw water using the difference between the obtained target value of the dissolved organic substance concentration and the dissolved organic substance concentration in the raw water and the powder activated carbon processing time derived from the raw water flow rate Injection rate calculating means,
A water quality monitoring control system comprising:

2. The water quality monitoring and control system according to claim 1, wherein the sum of the dissolved organic substance concentrations reduced by the water purification process in the water purification plant is subtracted from the raw water soluble organic substance concentration to correct the activated carbon injection rate.

The dissolved organic substance concentration reduced by the water purification step is a removal amount of the dissolved organic substance in the coagulation sedimentation tank step and the filtration tank step, and a conversion amount to a disinfection by-product by a reaction with chlorine. Item 3. A water quality monitoring and control system according to item 2.

Chlorine consumption prediction means for predicting chlorine consumption from the chlorine demand and the ammonia concentration measured by the raw water quality measurement means,
Disinfection chlorine consumption prediction means for predicting chlorine consumption by disinfection in the water purification plant,
Disinfection by-product conversion chlorine consumption prediction means for predicting disinfection by-product conversion chlorine consumption by the reaction of dissolved organic substances and chlorine remaining after the activated carbon injection treatment,
Chlorine injection rate calculating means for obtaining a chlorine injection rate from a preset chlorine concentration target value at the water purification plant outlet, the chlorine consumption, the disinfecting chlorine consumption, and the disinfecting by-product converted chlorine consumption,
The water quality monitoring and control system according to any one of claims 1 to 3, further comprising:

Based on the pipe diameter, pipe length, material, connection relationship between pipes, water pressure, and demand pattern prediction result of the water pipe network under the jurisdiction of the water purification plant, tap water flow between any two points on the water pipe network Flow time prediction means for predicting time;
Tap water flow velocity predicted value from the chlorine injection point determined by this flow time prediction means to any point on the water pipe network, and residual chlorine concentration at the outlet of the water purification plant, water temperature of tap water, water pipe material information and Using, residual chlorine concentration reduction rate prediction means for calculating and deriving the residual chlorine concentration reduction rate on the side located downstream,
A residual chlorine concentration prediction means for calculating and deriving a residual concentration at an arbitrary prediction point based on a prediction result by the residual chlorine concentration decrease rate prediction means,
Set the residual chlorine concentration at the outlet of the water treatment plant and set the chlorine injection rate so that the residual chlorine concentration at the terminal point of the water pipe network determined by this residual chlorine concentration prediction means does not become less than the preset minimum residual chlorine concentration. The water quality monitoring control system according to claim 4, wherein the water quality monitoring control system is determined.

Activated carbon required to reduce the dissolved organic matter concentration at the outlet of the water treatment plant so that the residual chlorine concentration at the end point of the water pipe network determined by the residual chlorine concentration prediction means does not fall below the preset minimum residual chlorine concentration. The water quality monitoring control system according to claim 5, wherein the injection amount is calculated and the activated carbon injection amount into the raw water is corrected.

If at least one of the fluorescence intensity of the raw water and the water temperature is higher than a preset value, the chlorine injection point is set as the intermediate chlorine injection point after the coagulation and sedimentation. The water quality monitoring control system according to any one of claims 1 to 6, further comprising a chlorine injection point control means serving as a chlorine injection point.

The sum of the amount of disinfection by-products generated in the water purification treatment process at the water purification plant and the amount of disinfection by-products generated by reacting with residual chlorine in the water pipe network due to the amount of dissolved organic substances at the outlet of the water purification plant, Calculate the amount of activated carbon required to reduce the concentration of dissolved organic substances at the outlet of the water treatment plant so that the concentration does not exceed the preset concentration of disinfection by-products at the water supply end. The water quality monitoring control system according to any one of claims 1 to 7, wherein the water quality monitoring control system is controlled.

2. A fluorescence analyzer for measuring the fluorescence intensity of purified water sent from a water purification plant, wherein the concentration of dissolved organic substances remaining in the purified water is estimated from the measured value of the fluorescence analyzer. Water quality monitoring and control system according to any one of claims 8 to 8.