JP3672158B2

JP3672158B2 - Turbidity measuring method and apparatus

Info

Publication number: JP3672158B2
Application number: JP05850198A
Authority: JP
Inventors: 太秀山口; 時喜雄大戸; 健治原田; 明徳佐々木
Original assignee: Fuji Electric Systems Co Ltd
Current assignee: Fuji Electric Co Ltd
Priority date: 1997-03-10
Filing date: 1998-03-10
Publication date: 2005-07-13
Anticipated expiration: 2018-03-10
Also published as: JPH10311784A

Description

【０００１】
【発明の属する技術分野】
本発明は濁度の測定方法および装置に関する。
【０００２】
【従来の技術】
水処理プロセスでは、原水や浄水の濁りの度合いを測定するために、濁度計が用いられており、透過光方式、散乱光方式、表面散乱光方式、透過−散乱光方式が採用されている。
【０００３】
透過光方式とは、光源から光ビームをフローセル内を通る試料水に照射したとき、被測定流体中を透過した光を光電変換器で受光し、変換された電圧を濁度に換算する方法であり、高濁度の試料水を測定するのに適している。
【０００４】
散乱光方式は、光源から光ビームをフローセル内を通る試料水に照射したとき、被測定流体中の微粒子によって散乱される光を光電変換器で受光し、変換された電圧を濁度に換算する方法であり、低濁度の試料水を測定するのに適している。
【０００５】
表面散乱光方式は、光源から光ビームを試料水の表面にフローセルを介さず、直接照射したとき、試料水の表面付近の微粒子によって散乱される光を光電変換器で受光し、変換された電圧を濁度に換算する方法であり、光ビーム照射域におけるフローセルと試料水の接触がない構造なので、フローセルの汚れの影響がないという特徴がある。
【０００６】
透過−散乱光方式は、散乱光強度を透過光強度で除算した量を濁度に換算する方法であり、低濁度から高濁度まで測定可能である。
【０００７】
【発明が解決しようとする課題】
最近の浄水の水質管理はクリプトスポリジウム等の対策のため厳しくなっており、現在のところ「クリプトスポリジウムによって水道原水が汚染されるおそれのある浄水場ではろ過池出口の濁度を０．１度以下に維持すること。」という暫定対策指針が厚生省から発表されている。そこで、必要となるのが濁度０．１度以下を安定して測定できるオンラインの濁度計であるのだが、このような低濁度になると観測領域中の微粒子の数はかなり少なくなるので、微粒子による光ビームの散乱や透過率を群として捕らえる従来の濁度計による測定は困難である。前記測定を実現するためには従来の濁度計のうち透過光方式では光路長を長くする、散乱光方式では光ビーム照射領域を大きくする等の改良により、観測領域中にある微粒子の存在確率を上げなければならない。しかし、前記改良は濁度計の光学系を大きくすることになるので、濁度測定の２桁以上の高感度化を行うことは大きさの制限上難しい。
【０００８】
また、膜処理の技術が水処理プロセスにおいても用いられ始めており、膜処理によって得られる処理水の安定性確保のために、濁度計や微粒子カウンタを用いて処理水をモニターしている。しかしながら従来の濁度計で検知できるのは膜の破断によって、原水が処理水側に著しく流出した場合であって、一部の膜の亀裂によるわずかな原水の流出は検知できず、このときの濁度の指示値は正常な膜処理水と同様ほぼゼロである。したがって、濁度測定では処理水の異常を早期に発見することは難しい。一方、微粒子カウンタは、処理水における膜の公称孔径以上の粒径をもった微粒子の個数濃度を測定し、膜の破断や亀裂があったときの微粒子の増加をモニターする。微粒子の個数濃度は、各々の微粒子によって散乱される光パルス、あるいは遮断される光パルスを一個ずつ数えるため、観測領域中の微粒子の存在確率が低い領域において、濁度と比較して感度がよく、膜異常の検知には微粒子カウンタが適している。ただし、観測領域中の微粒子の存在確率が高くなると、数え落とし誤差が生じるので注意を要する。
【０００９】
上述したように濁度０．１度以下の処理水や膜処理水などの極低濁域の測定では、従来の濁度計の感度は不十分であり、微粒子カウンタによる処理水中の微粒子個数濃度の測定が好ましい。一方、これまで水処理の分野では濁度を長年使用してきた歴史があり、浄水場等で測定された微粒子個数濃度の値をもとに水質を判断することに関して経験がない。
【００１０】
そこで、本発明の目的は、濁度測定が不可能な低濁域の領域にあっても測定可能な微粒子の個数濃度を濁度に変換して出力する有効な方法と装置を提供することにある。
【００１１】
【課題を解決するための手段】
上記目的を達成するため、請求項１の発明は、試料水に光ビームを照射し、試料水中の個々の微粒子によって散乱される光を光電変換手段で光電変換し、前記光ビーム中を前記個々の微粒子が通過する度に前記光電変換によって得られるパルス信号に基づいて、粒径区分ごとの試料水中の微粒子の個数濃度を求め、該各個数濃度に対して粒径区分ごとに個別の係数を乗じ、当該乗算結果の総和を試料水の濁度とすることを特徴とする。
【００１２】
また、請求項２の発明は、試料水に光ビームを照射し、試料水を透過する光を光電変換手段で光電変換し、前記光ビームを試料水中の個々の微粒子が遮断する度に前記光電変換によって得られるパルス信号に基づいて、粒径区分ごとの試料水中の微粒子の個数濃度を求め、該各個数濃度に対して粒径区分ごとに個別の係数を乗じ、当該乗算結果の総和を試料水の濁度とすることを特徴とする。
【００１３】
さらに、請求項３の発明は、請求項１または２において、前記個別の係数は、各粒径区分の平均粒径と、光ビームの波長と、試料水および微粒子の屈折率とに基づいて求める光散乱断面積であることを特徴とする。
【００１４】
さらに、請求項４の発明は、試料水に光ビームを照射し、試料水中の微粒子によって散乱される光を光電変換手段で光電変換し、前記光ビーム中を前記微粒子が通過する度に前記光電変換によって得られる単位時間内の各パルス信号の波高値を加算し、当該加算値に係数を乗じて試料水の濁度を求めることを特徴とする。
【００１５】
さらに、請求項５の発明は、試料水に光ビームを照射し、試料水を透過する光を光電変換手段で光電変換し、前記光ビームを前記微粒子が遮断する度に前記光電変換によって得られる単位時間内の各パルス信号の波高値を加算し、当該加算値に係数を乗じて試料水の濁度を求めることを特徴とする。
【００１６】
さらに、請求項６の発明は、請求項４または５において、前記係数は、前記光ビームの断面積を前記加算時の試料水の流量および前記光ビームの強度で除算した値に基づいて求めることを特徴とする。
【００１７】
さらに、請求項７の発明は、試料水に光ビームを照射する光源と、前記光ビーム照射領域内を通過する試料水中の個々の微粒子によって散乱される光を光電変換する光電変換手段と、前記光ビーム中を前記個々の微粒子が通過する度に前記光電変換手段から得られるパルス信号に基づいて、粒径区分ごとの試料水中の微粒子の個数濃度を求め、該各個数濃度に対して粒径区分ごとに個別の係数を乗じ、当該乗算結果の総和を試料水の濁度とする演算手段とを具えたことを特徴とする。
【００１８】
さらに、請求項８の発明は、試料水に光ビームを照射する光源と、前記光ビーム照射領域内を通過する試料水を透過する光を光電変換する光電変換手段と、前記光ビームを試料水中の個々の微粒子が遮断する度に前記光電変換手段から得られるパルス信号に基づいて、粒径区分ごとの試料水中の微粒子の個数濃度を求め、該各個数濃度に対して粒径区分ごとに個別の係数を乗じ、当該乗算結果の総和を試料水の濁度とする演算手段とを具えたことを特徴とする。
【００１９】
さらに、請求項９の発明は、請求項７または８において、前記個別の係数は、各粒径区分の平均粒径と、光ビームの波長と、試料水および微粒子の屈折率とに基づいて求める光散乱断面積であることを特徴とする。
【００２０】
さらに、請求項１０の発明は、試料水に光ビームを照射する光源と、前記光ビーム照射領域内を通過する試料水中の微粒子によって散乱される光を光電変換する光電変換手段と、前記光ビーム中を前記微粒子が通過する度に前記光電変換手段から得られる単位時間内の各パルス信号の波高値を加算し、当該加算値に係数を乗じて試料水の濁度を求める演算手段とを具えたことを特徴とする。
【００２１】
さらに、請求項１１の発明は、試料水に光ビームを照射する光源と、前記光ビーム照射領域内を通過する試料水を透過する光を光電変換する光電変換手段と、前記光ビームを前記微粒子が遮断する度に前記光電変換手段から得られる単位時間内の各パルス信号の波高値を加算し、当該加算値に係数を乗じて試料水の濁度を求める演算手段とを具えたことを特徴とする。
【００２２】
さらに、請求項１２の発明は、請求項１０または１１において、前記係数は、前記光ビームの断面積を前記加算時の試料水の流量および前記光ビームの強度で除算した値に基づいて求めることを特徴とする。
【００２３】
さらに、請求項１３の発明は、請求項７〜１２のいずれかにおいて、前記演算手段は、前記光電変換手段からのパルス信号の波高値を測定するピークホールド回路からの測定値に基づいて前記濁度を求めることを特徴とする。
【００２４】
さらに、請求項１４の発明は、請求項７，８，１０，１１のいずれかにおいて、前記演算手段は、前記光電変換手段からのパルス信号の波高値を各々異なったしきい値と比較する複数のコンパレータからの各比較出力に基づいて前記濁度を求めることを特徴とする。
さらに、請求項１５の発明は、請求項１または２において、前記個別の係数は、予め定めた粒径区分ごとの微粒子１個の濃度への寄与量であることを特徴とする。
【００２５】
【発明の実施の形態】
以下、図面を参照して本発明の実施形態を詳細に説明する。
【００２６】
（実施形態１）
光学系に前方散乱光方式を採用して濁度を測定する本発明の各実施形態に共通の装置の光学系を図１に示す。図１において光源１から照射された光ビーム１Ａは、フローセル２の光ビーム照射領域を通過する試料水中に存在する微粒子によって散乱される。試料水とフローセル２を通過する光源１からの直接光は、光源１から見てフローセル２の後ろ側に設置されたビームストップ３によって遮断され、ビームストップ３に設けた孔を通過した前記微粒子による散乱光の一部は光ビームの光軸４Ａと同一軸上に設置された集光レンズ４によって集められ、迷光を遮るために設けたピンホール５を通過した後、前記光ビームの光軸４Ａと同一軸上に設置された光電変換素子６によって電気信号に変換される。前記電気信号は図２のように光ビーム照射領域を微粒子が通過する度に、微粒子の大きさに応じた波高値を持つパルスとして検出される。前記検出された電気信号は、入力信号７として図３の電子回路に入力され、プリアンプ８、メインアンプ９で増幅された後、ローパスフィルタ（以後ＬＰＦ）１１にてノイズが除去される。一方、メインアンプ９から出力された電気信号をＬＰＦ１１よりカットオフ周波数が十分に低いＬＰＦ１０によって平滑することによって当該電気信号の平均値、すなわち迷光などによる直流成分が得られる。
【００２７】
次に、ＬＰＦ１０によって得られる当該電気信号の平均値を差動増幅部１２にて前記ＬＰＦ１１を通った電気信号から減算することにより、迷光などによる直流成分を差し引かれた電気信号が得られ、ピークホールド回路１３にて当該電気信号に発生したパルス信号の波高値が測定される。なお、例えば、フローセル内の試料水の流量が１０〜１００ｍｌ／分のとき、ＬＰＦ１０のカットオフ周波数は３０Ｈｚ以下、同様にＬＰＦ１１のそれは１００ｋＨｚ以上が好ましい。光ビーム照射領域を微粒子が通過してパルス信号が発生する度にピークホールド回路１３によって測定される前記波高値は、演算回路１４にてあらかじめ定めておいた粒径区分に相当するしきい値区分と比較し、粒径区分ごとにカウントしていく。サンプリング時間経過後、前記各区分毎のカウント数を単位時間当たりのカウント数に変換した値に係数を乗算し、サンプリング流量で除算すれば、各粒径区分ごとの微粒子の個数濃度を求められ、さらにその粒径区分ごとに異なる光散乱断面積を乗算すれば濁度を求めることができ、表示・出力回路１５にて濁度あるいは各粒径区分ごとの微粒子の個数濃度を表示・出力することができる。
【００２８】
上記の濁度測定の内容を数式で表すと以下のようになる。
【００２９】
まず、試料水中の微粒子の粒径ｄが一定、つまり単分散の場合、濁度Ｄ₁ は単位体積当たりの前記微粒子の個数ｎ₁ と前記微粒子の光散乱断面積Ｃ₁ を用いて、
【００３０】
【数１】
Ｄ₁ ＝ｎ₁ Ｃ₁ （１）
と表される。したがってこの場合、本発明の装置で観測され、微粒子の個数に比例するパルス信号の数に光散乱断面積を乗ずれば濁度となる。しかし、光散乱断面積は粒径によって変動する量であり、単分散の試料水を測定するならばよいが、実際の試料水が単分散であることは無いので、式（１）は通常の試料水に関しては成立しない。したがって、式（２）のように粒径区分ごとに個別の散乱断面積を各粒径区分ごとの微粒子個数濃度に乗算し、その和をとって濁度Ｄとしなければならない。
【００３１】
【数２】

【００３２】
Ｃ_d は微粒子の粒径区分ｄにおける光散乱断面積で、Ｍｉｅの光散乱論理によるシミュレーションで求めることができる。Ｍｉｅの光散乱理論は、波長よりも小さい微粒子で生じるレーリー散乱、波長と同程度の大きさの微粒子で生じるＭｉｅ散乱、波長よりも大きい微粒子で生じるフラウンホーファーの回折の全ての球状粒子に関する散乱光強度を、Ｍａｘｗｅｌｌの電磁方程式から完全解を得る理論である。具体的には、照射光の波長、試料水の屈折率、微粒子の屈折率、微粒子の半径に基づき、所定の受光領域で積分された散乱光強度に比例する光散乱断面積を計算するものである。図４は、以上の計算により、波長７８０ｎｍでの水中（屈折率１．３３）における屈折率１．５９５の材質からなる微粒子について、粒径と光散乱断面積の関係を示したものである。ｎ_d は単位体積当たりの粒径区分ｄにおける微粒子の個数であるが、本装置で測定される単位時間当たりの微粒子の個数Ｎ_d とサンプリング流量Ｆを用いれば式（２）は、
【００３３】
【数３】

【００３４】
と表すことができる。ここで例えば、粒径区分を▲１▼０．５〜１μｍ、▲２▼１〜２μｍ、▲３▼２μｍ以上というようにとると、式（３）は、
【００３５】
【数４】

【００３６】
と表される。ここで、Ｎ₁ 〜Ｎ₃ は粒径区分▲１▼〜▲３▼における単位時間当たりの微粒子の個数、Ｃ₁ 〜Ｃ₃ は光散乱シミュレーションから求められる各々の粒径区分内の光散乱断面積の平均値であり、Ｃ₁ ＝５．３２×１０^-13 、Ｃ₂ ＝５．３６×１０^-12 、Ｃ₃ ＝５．１８×１０^-11 である。
【００３７】
図５は実際に本発明装置に試料水を流量５０ｍＬ／分で流した結果の濁度演算値を示したものであり、比較のために、同試料水に適用した透過−散乱光方式の濁度計による測定値が０である低濁度においても本発明装置では、濁度測定が可能であり、従来の１０００倍の感度を持っていることが示された。
【００３８】
なお、試料水に含まれる微粒子のうち光を吸収する粒子が多く存在する場合には、光散乱シミュレーションから求められる光散乱断面積を粒径区分ごとの微粒子個数濃度に対して乗じるよりも、光散乱断面積と吸収断面積を足しあわせた減衰断面積を粒径区分ごとの微粒子個数濃度に対して乗じることにより濁度を求める方がより正確である。
【００３９】
また、本実施形態では光散乱断面積を粒径区分ごとの微粒子個数濃度に対して乗じることにより濁度を求めたが、あらかじめ実験により粒径区分ごとの微粒子１個の濁度への寄与量（濁度変換係数）を求めておき、その値を粒径区分ごとの微粒子個数濃度に対して乗算した後、各々を加算することで濁度を求めた方がよい場合もある。
【００４０】
なお、演算回路１４において、ＬＰＦ１０からの出力を観測し、当該出力が所定の上限値を越えた場合はフローセル２の汚れが測定に支障を与える状態になったことを検出し、当該出力が所定の下限値を下回った場合は光源１から光ビームが照射されなくなったこと、すなわち、光源１が異常状態になったことを検出しているので、各々の検出出力を表示・出力回路１５に供給し、その旨を表示する。
【００４１】
（実施形態２）
実施形態１ではピークホールド回路を用いて、パルス波高値を検出し、粒径区分ごとの微粒子個数濃度を測定したが、粒径区分が少なければ、図６のようにピークホールド回路の代りに粒径区分の数だけコンパレータを用意し、各粒径区分に対応するしきい値を設けて粒径区分ごとの微粒子個数濃度を測定してもよい。粒径区分を実施形態１と同様▲１▼０．５〜１μｍ、▲２▼１〜２μｍ、▲３▼２μｍ以上の三つにしたときの濁度測定について以下に記述する。
【００４２】
光ビーム照射領域を微粒子が通過する度に検出される微粒子の大きさに応じた波高値を持つ光電変換素子６からのパルス信号は実施形態１と同様に、入力信号１６として図６の電子回路に入力され、プリアンプ１７、メインアンプ１８で増幅された後、ローパスフィルタ（以後ＬＰＦ）２０にてノイズが除去される。次に前記ＬＰＦ２０を通った電気信号からＬＰＦ１９にて前記電気信号を平滑して得られる前記電気信号の平均値を差動増幅部２１にて減算することで、迷光などによる直流成分を差し引かれた電気信号は、コンパレータ２２〜２４に入力される。前記コンパレータのしきい値２２Ａ〜２４Ａを図７のように各粒径区分に対応した電圧に設定し、パルス信号を２値化して、各粒径区分に対応するしきい値以上の波高値を持つパルスを演算回路２５にてカウントすれば、実施形態１と同様に粒径区分ごとの微粒子個数濃度が測定され、その値に対して実施形態１と同様な演算を行うことにより、濁度を求めることができ、表示・出力回路２６にて濁度あるいは各粒径区分ごとの微粒子の個数濃度を表示・出力することができる。
【００４３】
（実施形態３）
実施形態１および２では粒径区分ごとに微粒子個数濃度を測定し濁度を求めたが、以下の方法により濁度を求めてもよい。
【００４４】
実施形態１と同様に微粒子によるパルス信号をピークホールドし、単位時間内の各パルスの波高値を演算回路にて加算し、前記波高値の加算値に係数を乗算する。ただし、粒径区分ごとの微粒子の個数濃度も合わせて測定する場合には、前記ピークホールドされた波高値を単位時間内で、そのまま記憶しておき、前記記憶された波高値の加算値に係数を乗算する。その結果得られた値が濁度であり、粒度分布の異なる試料水であっても従来の濁度との相関がある。なお、微粒子の個数濃度を測定する場合には、あらかじめ定めておいた粒径区分に相当するしきい値区分と前記記憶された波高値を比較し、粒径区分ごとにカウントする。
【００４５】
上記の濁度測定の内容を数式で表すと以下のようになる。
【００４６】
本装置で観測される粒径ｄを持った微粒子によるパルス波高値Ｖ_d は式（５）のようにＣ_d に比例した値である。
【００４７】
【数５】

【００４８】
ここで、Ｉ₀ は光ビームの強度、Ｗは光源の波長域における光電変換素子の受光感度、Ｒは光電変換された信号を電圧信号に変換するための負荷抵抗値、Ａ_v はプリアンプ、メインアンプを含めた回路の増幅率、Ｓは観測領域の光ビームの断面積である。したがって、実施形態１の式（３）では粒径区分ごとに観測された微粒子の個数濃度に対して一括して、前記粒径区分に対応する光散乱断面積を乗算して濁度としたが、本実施形態のように単位時間内で測定されるパルスの波高値を各々加算しても濁度を求めることができる。すなわち、単位時間内でＮ個のパルスが観測されたとすると、式（３）と（５）より濁度は、
【００４９】
【数６】

【００５０】
のように表すことができる。本式においては、粒径区分毎の総和を時系列的な総和におきかえるために、式（３）におけるｄはｉに、また式（３）に式（５）を代入することによって生ずる（Ｎ_d Ｖ_d ）はＶ_i におきかえて考えている。なお、Ｗ，ＲおよびＡ_V は回路定数であるので、前述の波高値の加算値に乗算する係数は、Ｓ／（ＦＩ₀ ）である。
【００５１】
本実施形態による方法は、実施形態１および２で記述した粒径区分を多数設けたことに相当するので、より精度の高い濁度測定を実現するという特徴がある。ただし、濁度と粒径区分ごとの微粒子の個数濃度を同時に測定する場合には、各パルス個別に波高値を記憶する必要があり、メモリの容量を余分に必要とするので、実施形態１あるいは２の方法を採用した方がよい場合もある。
【００５２】
なお、本実施形態では各微粒子のパルス波高値に光ビームの断面積を乗算し、サンプリング流量と光ビームの強度で除算することにより濁度を求めたが、あらかじめ濁度標準液を測定し、各微粒子のパルス波高値に乗じる係数を定めておく方がよい場合もある。
【００５３】
以上、実施形態１〜３では光学系に前方散乱光方式を採用したが、その他に側方散乱光方式や両者を組み合わせた光学系、あるいは光遮断方式などを用いてもよく、微粒子の個数濃度を粒径区分ごとに出力する機能があれば、容易に濁度に変換することが可能である。例えば、光遮断方式であれば、図１において、ビームストップ３の代りに、光ビーム１Ａのみを通過させる（すなわち、散乱光を遮断する）孔を有するストップを設け、このストップの孔を通過した光をピンホール５を介して光電変換素子６で光電変換すればよく、その出力は図３、図６の構成によって同様に処理することができる。
【００５４】
また、本発明はビーム内強度分布が均一な条件での測定が必要であるが、これを実現する方法として、例えば、特開平２−６２４６号に開示されているような偏平ビームを光源に用いる、または、特開昭６１−２８８１３９号に開示されているようなビームを走査する方法などが知られている。
【００５５】
【発明の効果】
本発明によれば、一つの微粒子が持っている濁度への寄与量を観測された微粒子毎に加算することで、従来の濁度計では困難であった低濁度における濁度測定を実現し、さらに粒度分布の異なる試料水を測定しても従来の濁度との相関のある濁度測定を可能とし、本発明は、ろ過池出口における水質の維持管理や、膜処理システムにおける膜モジュールの異常検知センサに使用することができる。
【図面の簡単な説明】
【図１】本発明装置の光学系の構成を示す図である。
【図２】微粒子によるパルス信号とパルス波高値との関係を示す図である。
【図３】本発明装置の電子回路系（ピークホールド回路使用）を示す図である。
【図４】粒径と光散乱断面積の関係を示す図である。
【図５】カオリン濃度と濁度演算値の関係を示す図である。
【図６】本装置の電子回路系（コンパレータ使用）を示す図である。
【図７】微粒子によるパルス信号とコンパレータのしきい値との関係を示す図である。
【符号の説明】
８プリアンプ
９メインアンプ
１０，１１ＬＰＦ
１２差動増幅部
１３ピークホールド回路
１４演算回路
１５表示・出力回路[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for measuring turbidity.
[0002]
[Prior art]
In the water treatment process, a turbidimeter is used to measure the turbidity of raw water or purified water, and a transmitted light method, a scattered light method, a surface scattered light method, and a transmitted-scattered light method are adopted. .
[0003]
The transmitted light method is a method in which when a sample beam passing through the flow cell is irradiated with a light beam from a light source, the light transmitted through the fluid to be measured is received by a photoelectric converter, and the converted voltage is converted to turbidity. Yes, suitable for measuring highly turbid sample water.
[0004]
In the scattered light method, when a sample beam passing through the flow cell is irradiated with a light beam from a light source, light scattered by fine particles in the fluid to be measured is received by a photoelectric converter, and the converted voltage is converted to turbidity. This method is suitable for measuring low turbidity sample water.
[0005]
In the surface scattered light method, when a light beam from a light source is directly applied to the surface of the sample water without passing through the flow cell, the light scattered by the fine particles near the surface of the sample water is received by the photoelectric converter, and the converted voltage is applied. Is a method for converting the turbidity into turbidity, and since there is no contact between the flow cell and the sample water in the light beam irradiation region, there is a feature that there is no influence of contamination of the flow cell.
[0006]
The transmitted-scattered light method is a method of converting an amount obtained by dividing the scattered light intensity by the transmitted light intensity into turbidity, and can measure from low turbidity to high turbidity.
[0007]
[Problems to be solved by the invention]
Recent water quality control for purified water has become strict due to countermeasures such as Cryptosporidium. Currently, "In water purification plants where raw water is likely to be contaminated by Cryptosporidium, the turbidity at the outlet of the filtration basin is 0.1 degrees or less. The Ministry of Health and Welfare has issued a provisional countermeasure guideline that “Keep it in the middle”. Therefore, what is needed is an on-line turbidimeter that can stably measure turbidity of 0.1 degrees or less, but when such a low turbidity is reached, the number of fine particles in the observation area is considerably reduced. Therefore, it is difficult to measure with a conventional turbidimeter that captures the scattering and transmittance of a light beam as a group. In order to realize the above measurement, the existence probability of fine particles in the observation region is improved by increasing the optical path length in the transmitted light method among the conventional turbidimeters and increasing the light beam irradiation region in the scattered light method. Must be raised. However, since the improvement increases the optical system of the turbidimeter, it is difficult to increase the sensitivity of two or more orders of turbidity measurement due to size limitations.
[0008]
Also, membrane treatment technology has begun to be used in water treatment processes, and in order to ensure the stability of treated water obtained by membrane treatment, the treated water is monitored using a turbidimeter and a fine particle counter. However, the conventional turbidimeter can detect when raw water has flowed out to the treated water side due to membrane breakage, and a slight outflow of raw water due to cracks in some membranes cannot be detected. The indication value of turbidity is almost zero as with normal membrane treated water. Therefore, it is difficult to detect abnormalities in treated water at an early stage by turbidity measurement. On the other hand, the fine particle counter measures the number concentration of fine particles having a particle diameter equal to or larger than the nominal pore size of the membrane in the treated water, and monitors the increase of the fine particles when the membrane is broken or cracked. The number concentration of fine particles counts the light pulses scattered or blocked by each fine particle one by one, so the sensitivity is better than the turbidity in the region where the existence probability of fine particles in the observation region is low. A fine particle counter is suitable for detecting a film abnormality. However, it should be noted that if the existence probability of the fine particles in the observation region is high, a counting error occurs.
[0009]
As described above, in the measurement of extremely low turbidity areas such as treated water having a turbidity of 0.1 degrees or less and membrane treated water, the sensitivity of the conventional turbidimeter is insufficient, and the fine particle number concentration in the treated water by the fine particle counter Is preferable. On the other hand, there is a history of using turbidity for many years in the field of water treatment so far, and there is no experience in judging water quality based on the value of the number concentration of fine particles measured at a water purification plant or the like.
[0010]
Accordingly, an object of the present invention is to provide an effective method and apparatus for converting the number concentration of fine particles that can be measured even in a low turbidity region where turbidity measurement is impossible, into turbidity and outputting it. is there.
[0011]
[Means for Solving the Problems]
To achieve the above object, the invention of claim 1, a light beam is irradiated to the sample water, and photoelectrically converted by the photoelectric conversion means light scattered by the individual particles of the water sample, wherein the light beam in the individual The number concentration of the fine particles in the sample water for each particle size category is obtained based on the pulse signal obtained by the photoelectric conversion every time the fine particles pass, and an individual coefficient for each particle size category is obtained for each number concentration. multiplied by the sum of the multiplication results, wherein the turbidity and to Rukoto of sample water.
[0012]
Further, the invention of claim 2 irradiates the sample water with a light beam, photoelectrically converts light transmitted through the sample water by a photoelectric conversion means, and the photoelectric beam is intercepted by each fine particle in the sample water. Based on the pulse signal obtained by the conversion, obtain the number concentration of fine particles in the sample water for each particle size category, multiply each number concentration by an individual coefficient for each particle size category, and add the sum of the multiplication results to the sample. and wherein the turbidity and be Rukoto of water.
[0013]
Furthermore, the invention of claim 3 is the invention according to claim 1 or 2, wherein the individual coefficient is obtained based on an average particle size of each particle size section, a wavelength of a light beam, and a refractive index of sample water and fine particles. It is a light scattering cross section.
[0014]
Further, the invention of claim 4 irradiates the sample water with a light beam, photoelectrically converts light scattered by the fine particles in the sample water by a photoelectric conversion means, and the photoelectric particles are passed through the light beam every time the fine particles pass through the light beam. The crest value of each pulse signal within a unit time obtained by the conversion is added, and the turbidity of the sample water is obtained by multiplying the added value by a coefficient.
[0015]
Furthermore, the invention of claim 5 is obtained by irradiating a sample water with a light beam, photoelectrically converting light transmitted through the sample water by a photoelectric conversion means, and obtaining the photoelectric conversion every time the light particles are blocked by the fine particles. The crest value of each pulse signal within a unit time is added, and the turbidity of the sample water is obtained by multiplying the added value by a coefficient.
[0016]
Further, the invention of claim 6 provides the method according to claim 4 or 5, wherein the coefficient is obtained based on a value obtained by dividing the cross-sectional area of the light beam by the flow rate of the sample water at the time of addition and the intensity of the light beam. It is characterized by.
[0017]
Furthermore, the invention of claim 7 is directed to a light source for irradiating a sample water with a light beam, a photoelectric conversion means for photoelectrically converting light scattered by individual fine particles in the sample water passing through the light beam irradiation region, and Based on the pulse signal obtained from the photoelectric conversion means each time the individual fine particles pass through the light beam, the number concentration of the fine particles in the sample water for each particle size category is obtained, and the particle size for each number concentration multiplied by the individual coefficients for each segment, characterized in that the sum of the multiplication results equipped with calculation means shall be the turbidity of the sample water.
[0018]
Furthermore, the invention of claim 8 is directed to a light source for irradiating a sample water with a light beam, a photoelectric conversion means for photoelectrically converting light passing through the sample water passing through the light beam irradiation area, and the light beam to the sample water. The number concentration of fine particles in the sample water for each particle size category is determined on the basis of the pulse signal obtained from the photoelectric conversion means each time the individual particles are blocked, and each particle size is individually determined for each particle size category. multiplied by a factor, characterized in that the sum of the multiplication results equipped with calculation means shall be the turbidity of the sample water.
[0019]
Further, the invention of claim 9 is the invention according to

claim

7 or 8, wherein the individual coefficient is obtained based on an average particle size of each particle size section, a wavelength of a light beam, and a refractive index of sample water and fine particles. It is a light scattering cross section.
[0020]
Furthermore, the invention of claim 10 is directed to a light source for irradiating a sample water with a light beam, a photoelectric conversion means for photoelectrically converting light scattered by fine particles in the sample water passing through the light beam irradiation region, and the light beam. Computation means for obtaining the turbidity of the sample water by adding the peak value of each pulse signal within a unit time obtained from the photoelectric conversion means each time the fine particles pass through and multiplying the added value by a coefficient. It is characterized by that.
[0021]
Furthermore, the invention of claim 11 is directed to a light source for irradiating a sample water with a light beam, a photoelectric conversion means for photoelectrically converting light passing through the sample water passing through the light beam irradiation region, and the light beam to the fine particles. And calculating means for adding the peak value of each pulse signal within a unit time obtained from the photoelectric conversion means each time the signal is cut off and multiplying the added value by a coefficient to obtain the turbidity of the sample water. And
[0022]
Further, the invention of claim 12 is the invention according to claim 10 or 11, wherein the coefficient is obtained based on a value obtained by dividing the cross-sectional area of the light beam by the flow rate of the sample water at the time of addition and the intensity of the light beam. It is characterized by.
[0023]
Furthermore, the invention of claim 13 provides the method according to any one of claims 7 to 12, wherein the computing means is based on a measured value from a peak hold circuit that measures a peak value of a pulse signal from the photoelectric converting means. It is characterized by determining the degree.
[0024]
Furthermore, in the invention of claim 14, in any of

claims

7, 8, 10, and 11, the arithmetic means compares a plurality of peak values of the pulse signal from the photoelectric conversion means with different threshold values. The turbidity is obtained based on each comparison output from the comparator.
Further, the invention of claim 15 is characterized in that, in claim 1 or 2, the individual coefficient is a contribution amount to the concentration of one fine particle for each predetermined particle size category.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0026]
(Embodiment 1)
FIG. 1 shows an optical system of an apparatus common to each embodiment of the present invention in which turbidity is measured by adopting a forward scattered light system in an optical system. In FIG. 1, the light beam 1 </ b> A emitted from the light source 1 is scattered by fine particles present in the sample water passing through the light beam irradiation region of the flow cell 2. Direct light from the light source 1 that passes through the sample water and the flow cell 2 is blocked by the beam stop 3 installed behind the flow cell 2 when viewed from the light source 1, and is caused by the fine particles that have passed through the holes provided in the beam stop 3. Part of the scattered light is collected by the condenser lens 4 installed on the same axis as the optical axis 4A of the light beam, passes through the pinhole 5 provided to block stray light, and then the optical axis 4A of the light beam. Is converted into an electrical signal by the photoelectric conversion element 6 installed on the same axis. The electric signal is detected as a pulse having a peak value corresponding to the size of the fine particle every time the fine particle passes through the light beam irradiation region as shown in FIG. The detected electrical signal is input as an input signal 7 to the electronic circuit of FIG. 3, amplified by a preamplifier 8 and a main amplifier 9, and then noise is removed by a low-pass filter (hereinafter LPF) 11. On the other hand, the electric signal output from the main amplifier 9 is smoothed by the LPF 10 having a cut-off frequency sufficiently lower than that of the LPF 11 to obtain an average value of the electric signal, that is, a direct current component due to stray light or the like.
[0027]
Next, by subtracting the average value of the electric signal obtained by the LPF 10 from the electric signal that has passed through the LPF 11 in the differential amplifying unit 12, an electric signal from which a direct current component due to stray light or the like is subtracted is obtained. The hold circuit 13 measures the peak value of the pulse signal generated in the electric signal. For example, when the flow rate of the sample water in the flow cell is 10 to 100 ml / min, the cutoff frequency of the LPF 10 is preferably 30 Hz or less, and similarly that of the LPF 11 is preferably 100 kHz or more. The peak value measured by the peak hold circuit 13 each time a fine particle passes through the light beam irradiation region and a pulse signal is generated is a threshold value segment corresponding to a particle size segment predetermined by the arithmetic circuit 14. And counting for each particle size category. After the sampling time has elapsed, multiply the value obtained by converting the count number for each section into the count number per unit time by a coefficient, and divide by the sampling flow rate, the number concentration of fine particles for each particle size section can be obtained, Furthermore, the turbidity can be obtained by multiplying the different light scattering cross sections for each particle size category, and the turbidity or the number concentration of fine particles for each particle size category can be displayed and output by the display / output circuit 15. Can do.
[0028]
The content of the above turbidity measurement is expressed as follows.
[0029]
First, when the particle diameter d of the fine particles in the sample water is constant, that is, monodisperse, the turbidity D ₁ is obtained by using the number n _{1 of the} fine particles per unit volume and the light scattering cross section C ₁ of the fine particles.
[0030]
[Expression 1]
D ₁ = n ₁ C ₁ (1)
It is expressed. Therefore, in this case, turbidity is obtained by multiplying the number of pulse signals observed by the apparatus of the present invention and proportional to the number of fine particles by the light scattering cross section. However, the light scattering cross section is an amount that varies depending on the particle size, and it is sufficient to measure monodispersed sample water. However, since actual sample water is not monodispersed, equation (1) It does not hold for sample water. Therefore, the turbidity D must be obtained by multiplying the individual scattering cross-sectional area for each particle size category by the fine particle number concentration for each particle size category and taking the sum as shown in Equation (2).
[0031]
[Expression 2]

[0032]
C _d is a light scattering cross section in the particle size classification _d of the fine particles, and can be obtained by simulation using Mie's light scattering logic. Mie's theory of light scattering is: Rayleigh scattering that occurs with fine particles smaller than the wavelength, Mie scattering that occurs with fine particles of the same size as the wavelength, and scattered light for all spherical particles of Fraunhofer diffraction that occurs with fine particles that are larger than the wavelength. This is a theory for obtaining a complete solution from Maxwell's electromagnetic equation. Specifically, it calculates the light scattering cross section proportional to the scattered light intensity integrated in a given light receiving area based on the wavelength of the irradiation light, the refractive index of the sample water, the refractive index of the fine particles, and the radius of the fine particles. is there. FIG. 4 shows the relationship between the particle size and the light scattering cross section of fine particles made of a material having a refractive index of 1.595 in water (refractive index of 1.33) at a wavelength of 780 nm by the above calculation. n _d is the number of fine particles in the particle size classification d per unit volume, but using the number N _d of fine particles per unit time measured by this apparatus and the sampling flow rate F, Equation (2) is
[0033]
[Equation 3]

[0034]
It can be expressed as. Here, for example, when the particle size classification is taken as (1) 0.5 to 1 μm, (2) 1 to 2 μm, (3) 2 μm or more, the formula (3) becomes
[0035]
[Expression 4]

[0036]
It is expressed. Here, N _{1 to} N ₃ are the number of fine particles per unit time in the particle size categories {circle around (1)} to {circle around (3)}, and C _{1 to} C ₃ are light scattering breaks in the respective particle size categories determined from light scattering simulations. The average values of the areas are C ₁ = 5.32 × 10 ⁻¹³ , C ₂ = 5.36 × 10 ⁻¹² , and C ₃ = 5.18 × 10 ⁻¹¹ .
[0037]
FIG. 5 shows the turbidity calculation value as a result of actually flowing sample water at a flow rate of 50 mL / min to the apparatus of the present invention. For comparison, the turbidity of the transmitted-scattered light method applied to the sample water is shown. It was shown that the device of the present invention can measure turbidity even at low turbidity where the measured value by a spectrophotometer is 0, and has 1000 times the sensitivity.
[0038]
In addition, when there are many particles that absorb light among the fine particles contained in the sample water, the light scattering cross section obtained from the light scattering simulation is multiplied by the fine particle number concentration for each particle size category. It is more accurate to obtain the turbidity by multiplying the attenuation cross-section obtained by adding the scattering cross-section and the absorption cross-section to the fine particle concentration for each particle size category.
[0039]
Further, in this embodiment, the turbidity is obtained by multiplying the light scattering cross-sectional area by the fine particle number concentration for each particle size category. However, the amount of contribution to the turbidity of one fine particle for each particle size category is determined in advance by experiments. In some cases, it is better to obtain (turbidity conversion coefficient), multiply the value by the fine particle number concentration for each particle size category, and then add each of them to obtain the turbidity.
[0040]
In the arithmetic circuit 14, the output from the LPF 10 is observed, and when the output exceeds a predetermined upper limit value, it is detected that the contamination of the flow cell 2 has interfered with the measurement, and the output is predetermined. When the value falls below the lower limit value, it is detected that the light source 1 is no longer irradiated, that is, that the light source 1 is in an abnormal state, so that each detection output is supplied to the display / output circuit 15. And a message to that effect is displayed.
[0041]
(Embodiment 2)
In the first embodiment, the peak value is detected using the peak hold circuit, and the number concentration of fine particles for each particle size category is measured. However, if the particle size category is small, the particle size instead of the peak hold circuit is used as shown in FIG. Comparators may be prepared as many as the number of diameter sections, and a threshold value corresponding to each particle diameter section may be provided to measure the fine particle number concentration for each particle diameter section. The turbidity measurement when the particle size classification is set to three, ie, (1) 0.5 to 1 μm, (2) 1 to 2 μm, and (3) 2 μm or more, as in Embodiment 1, is described below.
[0042]
A pulse signal from the photoelectric conversion element 6 having a peak value corresponding to the size of the fine particle detected each time the fine particle passes through the light beam irradiation region is input as an input signal 16 as in the first embodiment. Is amplified by the preamplifier 17 and the main amplifier 18, and then noise is removed by a low-pass filter (hereinafter LPF) 20. Next, by subtracting the average value of the electrical signal obtained by smoothing the electrical signal with the LPF 19 from the electrical signal that has passed through the LPF 20 with the differential amplifier 21, a direct current component due to stray light or the like is subtracted. The electrical signal is input to the comparators 22-24. The threshold values 22A to 24A of the comparators are set to voltages corresponding to each particle size segment as shown in FIG. 7, the pulse signal is binarized, and a peak value equal to or higher than the threshold value corresponding to each particle size segment is set. When the number of pulses is counted by the arithmetic circuit 25, the fine particle number concentration for each particle size category is measured in the same manner as in the first embodiment, and the turbidity is determined by performing the same calculation as in the first embodiment on the value. The display / output circuit 26 can display / output the turbidity or the number concentration of fine particles for each particle size category.
[0043]
(Embodiment 3)
In Embodiments 1 and 2, the turbidity was determined by measuring the fine particle number concentration for each particle size category, but the turbidity may be determined by the following method.
[0044]
As in the first embodiment, the pulse signal by the fine particles is peak-held, the peak value of each pulse within a unit time is added by an arithmetic circuit, and the added value of the peak values is multiplied by a coefficient. However, when the number concentration of fine particles for each particle size category is also measured, the peak-held peak value is stored as it is within a unit time, and a coefficient is added to the added value of the stored peak values. Multiply The value obtained as a result is turbidity, and even sample water having a different particle size distribution has a correlation with conventional turbidity. When measuring the number concentration of fine particles, the threshold value section corresponding to a predetermined particle diameter section is compared with the stored peak value and counted for each particle diameter section.
[0045]
The content of the above turbidity measurement is expressed as follows.
[0046]
The pulse peak value V _d due to the fine particles having the particle diameter d observed by this apparatus is a value proportional to C _d as shown in Equation (5).
[0047]
[Equation 5]

[0048]
Here, I ₀ is the intensity of the light beam, W is the light receiving sensitivity of the photoelectric conversion element in the wavelength range of the light source, R is a load resistance value for converting the photoelectrically converted signal into a voltage signal, _Av is a preamplifier, main The amplification factor of the circuit including the amplifier, S, is the cross-sectional area of the light beam in the observation region. Therefore, in Formula (3) of Embodiment 1, turbidity is obtained by multiplying the number concentration of fine particles observed for each particle size category by the light scattering cross section corresponding to the particle size category. The turbidity can also be obtained by adding the pulse peak values measured within a unit time as in this embodiment. That is, if N pulses are observed within a unit time, the turbidity is calculated from the equations (3) and (5).
[0049]
[Formula 6]

[0050]
It can be expressed as In this equation, d in equation (3) is generated by substituting i into equation (3) and equation (5) into equation (3) in order to replace the total for each particle size category with time-series summation (N _d V _d ) is replaced with V _i . Since W, R, and A _V are circuit constants, the coefficient that is multiplied by the added value of the peak value is S / (FI ₀ ).
[0051]
The method according to the present embodiment corresponds to providing a large number of particle size classifications described in the first and second embodiments, and thus has a feature of realizing more accurate turbidity measurement. However, in the case of simultaneously measuring the turbidity and the number concentration of fine particles for each particle size category, it is necessary to store the crest value for each pulse individually, and an extra memory capacity is required. In some cases, it is better to adopt the second method.
[0052]
In this embodiment, the pulse peak value of each fine particle is multiplied by the cross-sectional area of the light beam, and the turbidity is obtained by dividing by the sampling flow rate and the intensity of the light beam, but the turbidity standard solution is measured in advance, In some cases, it is better to determine a coefficient by which the pulse peak value of each particle is multiplied.
[0053]
As described above, in the first to third embodiments, the forward scattered light method is used for the optical system. However, a side scattered light method, an optical system that combines both, or a light blocking method may be used. Can be easily converted into turbidity if there is a function of outputting the value for each particle size category. For example, in the case of the light blocking method, in FIG. 1, instead of the beam stop 3, a stop having a hole that allows only the light beam 1A to pass (that is, blocks the scattered light) is provided, and the hole passed through this stop hole. Light may be photoelectrically converted by the photoelectric conversion element 6 through the pinhole 5, and the output can be similarly processed by the configurations of FIGS.
[0054]
Further, the present invention requires measurement under a condition in which the intensity distribution in the beam is uniform. As a method for realizing this, for example, a flat beam as disclosed in JP-A-2-6246 is used as a light source. Alternatively, a method of scanning a beam as disclosed in JP-A-61-288139 is known.
[0055]
【The invention's effect】
According to the present invention, turbidity measurement at low turbidity, which was difficult with conventional turbidimeters, is realized by adding the amount of contribution to turbidity possessed by one fine particle for each observed fine particle. Furthermore, even if sample waters having different particle size distributions are measured, turbidity measurement having a correlation with conventional turbidity can be performed, and the present invention can maintain and maintain water quality at the outlet of a filtration basin, and a membrane module in a membrane treatment system. It can be used as an abnormality detection sensor.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an optical system of an apparatus according to the present invention.
FIG. 2 is a diagram showing a relationship between a pulse signal by a fine particle and a pulse peak value.
FIG. 3 is a diagram showing an electronic circuit system (using a peak hold circuit) of the device of the present invention.
FIG. 4 is a diagram showing the relationship between particle size and light scattering cross section.
FIG. 5 is a diagram showing the relationship between kaolin concentration and turbidity calculation value.
FIG. 6 is a diagram showing an electronic circuit system (using a comparator) of the present apparatus.
FIG. 7 is a diagram showing a relationship between a pulse signal caused by fine particles and a threshold value of a comparator.
[Explanation of symbols]
8 Preamplifier 9

Main amplifier

10, 11 LPF
12 Differential Amplifier 13 Peak Hold Circuit 14 Arithmetic Circuit 15 Display / Output Circuit

Claims

A pulse obtained by irradiating the sample water with a light beam, photoelectrically converting light scattered by the individual fine particles in the sample water by photoelectric conversion means, and by the photoelectric conversion each time the individual fine particles pass through the light beam based on the signal, determine the number concentration of fine particles in water sample per particle size range, multiplied by the individual coefficients for each particle size range with respect to respective number concentration, and the sum of the multiplication results of sample water turbidity method of measuring the turbidity of said to Rukoto.

The sample water is irradiated with a light beam, the light passing through the sample water is photoelectrically converted by the photoelectric conversion means, and the light beam is based on the pulse signal obtained by the photoelectric conversion each time the fine particles in the sample water are blocked. , determine the number concentration of fine particles in water sample per particle size range, multiplied by the individual coefficients for each particle size range with respect to respective number concentration, the sum of the multiplication results of turbidity and to Rukoto water sample A characteristic method for measuring turbidity.

3. The individual coefficient according to claim 1, wherein the individual coefficient is a light scattering cross section obtained based on an average particle diameter of each particle size section, a wavelength of a light beam, and a refractive index of sample water and fine particles. A method for measuring turbidity.

The sample water is irradiated with a light beam, light scattered by the fine particles in the sample water is photoelectrically converted by a photoelectric conversion means, and each time within the unit time obtained by the photoelectric conversion each time the fine particles pass through the light beam. A method for measuring turbidity, comprising adding a peak value of a pulse signal and multiplying the added value by a coefficient to obtain turbidity of sample water.

The sample water is irradiated with a light beam, the light passing through the sample water is photoelectrically converted by a photoelectric conversion means, and each pulse signal wave within a unit time obtained by the photoelectric conversion every time the fine particle blocks the light beam. A method for measuring turbidity, comprising adding a high value and multiplying the added value by a coefficient to obtain the turbidity of sample water.

6. The turbidity measuring method according to claim 4, wherein the coefficient is obtained based on a value obtained by dividing the cross-sectional area of the light beam by the flow rate of the sample water at the time of addition and the intensity of the light beam. .

A light source for irradiating a light beam to the sample water, and photoelectric conversion means for photoelectrically converting the light scattered by the individual particles of sample water passing through the light beam irradiation area, travels in the light beam the individual particles Based on the pulse signal obtained from the photoelectric conversion means each time it passes, the number concentration of the fine particles in the sample water for each particle size category is determined, and each number concentration is multiplied by an individual coefficient for each particle size category , measuring device turbidity, characterized in that the sum of the multiplication results equipped with calculation means shall be the turbidity of the sample water.

A light source that irradiates the sample water with a light beam, photoelectric conversion means that photoelectrically converts light that passes through the sample water passing through the light beam irradiation region, and each fine particle in the sample water blocks the light beam. Based on the pulse signal obtained from the photoelectric conversion means, obtain the number concentration of fine particles in the sample water for each particle size category, multiply the number concentration by an individual coefficient for each particle size category , measuring device turbidity, characterized in that summing equipped with calculation means shall be the turbidity of the sample water.

9. The individual coefficient according to claim 7 or 8, wherein the individual coefficient is a light scattering cross section obtained based on an average particle diameter of each particle size section, a wavelength of a light beam, and a refractive index of sample water and fine particles. A turbidity measuring device.

A light source for irradiating the sample water with a light beam, photoelectric conversion means for photoelectrically converting light scattered by the fine particles in the sample water passing through the light beam irradiation region, and each time the fine particles pass through the light beam The turbidity of the turbidity is characterized by comprising a calculating means for adding the peak value of each pulse signal obtained from the photoelectric conversion means within a unit time and multiplying the added value by a coefficient to obtain the turbidity of the sample water. measuring device.

A light source for irradiating a sample water with a light beam, a photoelectric conversion means for photoelectrically converting light that passes through the sample water passing through the light beam irradiation area, and the photoelectric conversion means each time the light beam is blocked by the fine particles A turbidity measuring device comprising: a calculating means for adding the peak values of each pulse signal obtained in a unit time and multiplying the added value by a coefficient to obtain the turbidity of the sample water.

12. The turbidity measuring device according to claim 10, wherein the coefficient is obtained based on a value obtained by dividing the cross-sectional area of the light beam by the flow rate of the sample water at the time of addition and the intensity of the light beam. .

12. The calculation means according to claim 7, wherein the calculation means obtains the turbidity based on a measurement value from a peak hold circuit that measures a peak value of a pulse signal from the photoelectric conversion means. A characteristic turbidity measuring device.

12. The calculation means according to claim 7, wherein the calculation means is based on each comparison output from a plurality of comparators for comparing the peak value of the pulse signal from the photoelectric conversion means with different threshold values. The turbidity measuring device is characterized by determining the turbidity.

3. The method for measuring turbidity according to claim 1, wherein the individual coefficient is a contribution amount to the concentration of one fine particle for each predetermined particle size category.