JPH0954036A - Cr concentration meter - Google Patents
Cr concentration meterInfo
- Publication number
- JPH0954036A JPH0954036A JP20976995A JP20976995A JPH0954036A JP H0954036 A JPH0954036 A JP H0954036A JP 20976995 A JP20976995 A JP 20976995A JP 20976995 A JP20976995 A JP 20976995A JP H0954036 A JPH0954036 A JP H0954036A
- Authority
- JP
- Japan
- Prior art keywords
- light
- concentration
- hexavalent chromium
- signal
- waste liquid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、例えばメッキ工場
における廃液処理設備で処理される廃液などに含まれる
６価クロム濃度を測定するためのCr濃度計に関するもの
である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Cr concentration meter for measuring the concentration of hexavalent chromium contained in a waste liquid treated in a waste liquid treatment facility in a plating factory, for example.
【０００２】[0002]
【従来の技術】鉄鋼、自動車、電子産業等ではクロムメ
ッキが多用される。これらメッキ工場から排出される廃
液中の６価クロムは人体に有害なため、公共水域に放流
する際の濃度が、水質汚濁防止法により環境基準値0.05
mg／リットル（0.05ppm)以下に規制されている。2. Description of the Related Art Chrome plating is frequently used in the steel, automobile, and electronics industries. Since hexavalent chromium in the waste liquid discharged from these plating plants is harmful to humans, its concentration when discharged into public waters has an environmental standard value of 0.05 according to the Water Pollution Control Law.
It is regulated to mg / liter (0.05 ppm) or less.
【０００３】現在、上記の環境基準値近傍での６価クロ
ム濃度を測定するために、測定範囲が０〜１ppm の低濃
度領域の６価クロム濃度計（以下、Cr濃度計と略記す
る）が実用化されている。この濃度計は、図11に示すよ
うな吸光度測定方式に基づく構成を有し、廃液80が注入
されるガラス容器から成る光学セル81が設けられると共
に、この光学セル81を挟んで、例えば水銀ランプから成
る光源82と受光器83とが配置されている。そして、光学
セル81に注入される廃液80にジフェニルカルバジド試薬
を添加して発色反応を生じさせ、これに、中心波長540n
m の光を光源82から照射し、この光を光学セル81に透過
させたときの受光器83での受光強度から、廃液中の６価
クロム濃度を測定するようになっている。At present, a hexavalent chromium concentration meter (hereinafter abbreviated as Cr concentration meter) in a low concentration range of 0 to 1 ppm is used to measure the hexavalent chromium concentration near the above environmental standard value. Has been put to practical use. This densitometer has a configuration based on an absorbance measurement method as shown in FIG. 11, and is provided with an optical cell 81 composed of a glass container into which a waste liquid 80 is injected. A light source 82 and a light receiver 83 are arranged. Then, a diphenylcarbazide reagent is added to the waste liquid 80 injected into the optical cell 81 to cause a color-forming reaction.
The light of m 2 is emitted from the light source 82, and the concentration of hexavalent chromium in the waste liquid is measured from the intensity of light received by the light receiver 83 when this light is transmitted through the optical cell 81.
【０００４】一方、前記のメッキ工場等における廃液処
理設備での処理プロセスについて、本発明の説明図であ
る図２を参照して説明すると、各工場からの通常数百〜
数千ppm の高濃度の６価クロムを含む廃液がメッキ廃水
槽１・２に受け入れられ、その後、一次pH調整槽３に送
られて硫酸が添加されpHが調整される。次いで、還元槽
４に送られ、ここで、還元剤としての重亜硫酸ソーダが
注入されて６価クロムが無害な３価クロムに還元され
る。その後、二次・三次pH調整槽５・６にて注入される
水酸化ナトリウムで中和処理が行われ、３価クロムは水
に不溶性の水酸化クロムとなる。これが、次の沈澱槽７
にて沈降分離される。[0004] On the other hand, the treatment process in the waste liquid treatment equipment in the plating plant and the like will be described with reference to FIG. 2 which is an explanatory diagram of the present invention.
Wastewater containing hexavalent chromium having a high concentration of several thousand ppm is received in the plating wastewater tanks 1 and 2 and then sent to the primary pH adjusting tank 3 where sulfuric acid is added to adjust the pH. Next, the mixture is sent to a reduction tank 4 where sodium bisulfite as a reducing agent is injected to reduce hexavalent chromium to harmless trivalent chromium. After that, neutralization is performed with sodium hydroxide injected in the secondary and tertiary pH adjusting tanks 5 and 6, and trivalent chromium becomes insoluble chromium hydroxide in water. This is the next settling tank 7
Is settled and separated.
【０００５】分離されたクロムは、その他の亜鉛や鉄な
どの金属と共にスラッジ貯槽に回収される一方、沈澱槽
７の上澄水が次段の集合原水槽に送られ、濃度の確認を
行ったうえで放流される。このような廃液処理プロセス
において、前記のCr濃度計は、最終的な放流直前での濃
度測定に使用される。しかしながら、処理途中の廃液に
対しては、その濃度が測定範囲から大きく逸脱するた
め、上記のCr濃度計での直接的な測定は不可能である。
一方、高濃度領域の測定が可能なCr濃度計は現在まで実
用化されておらず、このため、廃液処理の途中のプロセ
スでは、化学分析などによる定期的な濃度測定が行われ
るものの、日常的な条件設定は、上記の濃度測定結果を
目安としながら運転員によって試行錯誤的に行われてい
る。例えば、廃液は６価クロム濃度に応じて黄色の色合
いを呈することから、一次pH調整槽３の廃液の色を目視
により観察して濃度を推定し、また、還元槽４での還元
処理後の液の状態から反応状態を観察して、単位時間当
たりの処理量や、還元槽４への重亜硫酸ソーダなどの薬
剤の注入量が調整されている。[0005] The separated chromium is collected in a sludge storage tank together with other metals such as zinc and iron, and the supernatant water of the precipitation tank 7 is sent to the next collecting raw water tank to check the concentration. It is released at. In such a waste liquid treatment process, the above-mentioned Cr concentration meter is used for concentration measurement immediately before final discharge. However, the concentration of the waste liquid in the middle of treatment greatly deviates from the measurement range, so that direct measurement with the above-mentioned Cr concentration meter is impossible.
On the other hand, a Cr concentration meter capable of measuring a high concentration region has not been put into practical use until now.Thus, in the process of waste liquid treatment, periodic concentration measurement by chemical analysis etc. is performed, The conditions are set by trial and error by the operator using the above-mentioned concentration measurement results as a guide. For example, since the waste liquid has a yellow tint in accordance with the hexavalent chromium concentration, the concentration of the waste liquid in the primary pH adjustment tank 3 is visually observed to estimate the concentration. By observing the reaction state from the state of the liquid, the processing amount per unit time and the injection amount of a chemical such as sodium bisulfite into the reduction tank 4 are adjusted.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、上記の
ように廃液処理のプロセス条件を運転員の目視観察に基
づいて行ったのでは、６価クロム濃度の正確な把握が困
難であるために、薬剤の過剰投入が行われがちになり、
このため、廃液処理コストが高くなるという問題を生じ
ている。However, if the wastewater treatment process conditions are based on the visual observation of the operator as described above, it is difficult to accurately grasp the hexavalent chromium concentration. Tend to be overdosed,
For this reason, there has been a problem that the waste liquid treatment cost is high.
【０００７】また、運転員にとっても、目視による監視
を度々行わなければならず、しかも、例えば強風時に廃
液飛散に対する注意も払いながら廃液槽を上方から覗き
込むという過酷な作業でもあり、その作業性の向上が望
まれている。そこで、例えば一次pH調整槽３での６価ク
ロム濃度を前記したCr濃度計で測定し、その測定結果に
応じてプロセス条件の設定を行うようにすることが考え
られる。しかしながら、この場合、上記のCr濃度計にお
ける０〜１ppm の測定範囲に入るように、予め測定対象
の廃液を希釈する前処理が必要となる。このとき、対象
廃液の濃度は大きく変動するために希釈度合いが不明で
あり、このため、例えば廃液サンプルを種々の希釈度で
希釈し、これらを順次測定するなどの作業が必要になっ
て長時間を要すると共に、作業が極めて煩雑になる。In addition, the operator must frequently perform visual monitoring. In addition, the operator is required to look into the waste liquid tank from above while paying attention to the scattering of the waste liquid in strong winds. There is a demand for improvement. Therefore, for example, it is conceivable to measure the hexavalent chromium concentration in the primary pH adjusting tank 3 with the above-mentioned Cr concentration meter and to set process conditions according to the measurement result. However, in this case, it is necessary to perform a pretreatment for diluting the waste liquid to be measured in advance so as to fall within the measurement range of 0 to 1 ppm in the Cr concentration meter. At this time, since the concentration of the target waste liquid greatly fluctuates, the degree of dilution is unknown. And the operation becomes extremely complicated.
【０００８】また、上記Cr濃度計では、前記したよう
に、試薬を加え発色反応後測定する方式であるため、試
薬の管理費等も必要になって運用コストの高騰を招来す
る。本発明は、上記した従来の問題点に鑑みなされたも
ので、その目的は、前記した廃液処理設備などに容易に
適用し得るように、被測定対象液中の６価クロム濃度の
測定が高濃度領域まで可能であると共に、測定の信頼性
に優れ、また、取扱いが容易でコスト的にも有利なCr濃
度計を提供することにある。Further, as described above, since the above-mentioned Cr concentration meter uses a method in which a reagent is added and measurement is carried out after a color-forming reaction, the management cost of the reagent is also required, resulting in an increase in operating costs. The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to measure the concentration of hexavalent chromium in a liquid to be measured at a high level so that it can be easily applied to the waste liquid treatment facility described above. An object of the present invention is to provide a Cr concentration meter which is capable of controlling the concentration range, has excellent measurement reliability, is easy to handle, and is advantageous in terms of cost.
【０００９】[0009]
【課題を解決するための手段】上記の目的を達成するた
めに、本発明の請求項１のCr濃度計は、６価クロム溶液
における吸光度がピークになる近紫外領域での波長から
青色側に偏倚した波長を中心波長とする光を出射する投
光手段と、投光手段から出射されて溶液を透過した光を
受光する受光手段と、受光手段から受光量に応じて出力
される強度信号に基づき溶液中の６価クロム濃度に応ず
る信号を出力する信号処理手段とを備えていることを特
徴としている。In order to achieve the above object, the Cr densitometer according to claim 1 of the present invention has a wavelength of blue in the near-ultraviolet region where the absorbance in a hexavalent chromium solution peaks. A light projecting unit that emits light having a deviated wavelength as a central wavelength, a light receiving unit that receives light emitted from the light projecting unit and transmitted through the solution, and an intensity signal output from the light receiving unit according to the amount of light received. And a signal processing means for outputting a signal corresponding to the concentration of hexavalent chromium in the solution.
【００１０】このように溶液での吸光度から濃度を求め
る場合、透過光の強度は濃度と吸光度係数との積に対し
て指数関数的に低下する。つまり、吸光度係数が小さい
と、濃度が高くなっても透過光強度の低下の度合いが小
さくなる。そこで上記では、６価クロム溶液における吸
光度係数が適度に小さくなる波長の光、すなわち、吸光
度がピークになる近紫外領域での波長領域から青色側に
偏倚した波長の光を出射する投光手段を設け、この光に
対する６価クロム溶液の吸光度を検出する。これによっ
て、より高濃度域まで、濃度変化に応じた透過光強度の
変化を検出することが可能となる。この結果、例えば０
〜4000ppm の広い測定範囲を有するCr濃度計として構成
することができる。When the concentration is determined from the absorbance in the solution as described above, the intensity of the transmitted light decreases exponentially with respect to the product of the concentration and the absorbance coefficient. In other words, when the absorbance coefficient is small, the degree of decrease in transmitted light intensity decreases even when the concentration increases. Therefore, in the above description, a light projecting unit that emits light having a wavelength at which the absorbance coefficient of the hexavalent chromium solution becomes appropriately small, that is, light having a wavelength deviated toward the blue side from the wavelength region in the near ultraviolet region where the absorbance peaks. The absorbance of the hexavalent chromium solution with respect to this light is detected. This makes it possible to detect a change in transmitted light intensity according to a change in density up to a higher density range. As a result, for example, 0
It can be configured as a Cr concentration meter having a wide measuring range of up to 4000 ppm.
【００１１】請求項２のCr濃度計は、投光手段に設けら
れる光源が、４５０ｎｍを中心波長とする光を出射する
青色発光ダイオードから成ることを特徴としている。こ
のように青色発光ダイオードを光源として用いることに
より、小形化や軽量化、さらに長寿命化が図れ、安価で
取扱いの容易な装置構成とすることができる。請求項３
のCr濃度計は、投光手段に設けられる光源に所定の周波
数の高周波電圧を印加して出射光を点滅させる高周波電
源が設けられると共に、受光手段からの強度信号から上
記周波数成分の信号を抽出するバンドパスフィルタが前
記信号処理手段に設けられていることを特徴としてい
る。The Cr densitometer according to a second aspect is characterized in that the light source provided in the light projecting means is composed of a blue light emitting diode which emits light having a central wavelength of 450 nm. By using a blue light emitting diode as a light source in this manner, a compact, lightweight, and long-life device can be achieved, and a device configuration that is inexpensive and easy to handle can be provided. Claim 3
The Cr densitometer is equipped with a high-frequency power source that applies a high-frequency voltage of a predetermined frequency to the light source provided in the light projecting means to blink the emitted light, and extracts the signal of the frequency component from the intensity signal from the light receiving means. The signal processing means is provided with a bandpass filter for performing the above.
【００１２】このように光源からの出射光を点滅させ、
この点滅光での吸光度に基づいてCr濃度の検出を行うこ
とにより、例えば屋外で使用する場合等における外乱光
の影響が防止され、この結果、より精度の高い検出を行
うことができる。請求項４のCr濃度計は、投光手段を収
納する投光ハウジングと受光手段を収納する受光ハウジ
ングとが所定の間隔で配置されると共に、これら両ハウ
ジングがそれぞれ水密構造で形成されていることを特徴
としている。In this way, the light emitted from the light source is made to blink,
By detecting the Cr concentration based on the absorbance of the blinking light, the influence of disturbance light in, for example, outdoor use is prevented, and as a result, more accurate detection can be performed. According to another aspect of the Cr concentration meter of the present invention, a light projecting housing for housing the light projecting means and a light receiving housing for housing the light receiving means are arranged at a predetermined interval, and both housings are formed in a watertight structure. Is characterized by.
【００１３】このように水密構造であることにより、両
ハウジングを例えば廃液処理槽中の廃液に直接浸漬させ
て連続測定することが可能になる。したがって、廃液処
理槽から廃液を別途測定用の光学セルに導いて測定する
ような構成とする必要はなく、従来の廃液処理槽等にそ
のまま適用できるので、運用コストが低減されると共に
操作性が向上する。特に、光源が発光ダイオードから成
る構成では、この光源を作動させるために高電圧を印加
する必要はないので、安全性も充分に確保される。With such a watertight structure, both housings can be directly immersed in, for example, the waste liquid in the waste liquid treatment tank for continuous measurement. Therefore, it is not necessary to adopt a configuration in which the waste liquid is separately guided from the waste liquid treatment tank to the optical cell for measurement, and the measurement can be applied to the conventional waste liquid treatment tank, etc., so that the operation cost is reduced and the operability is reduced. improves. In particular, in a configuration in which the light source is composed of a light emitting diode, it is not necessary to apply a high voltage to operate the light source, so that sufficient safety is ensured.
【００１４】請求項５のCr濃度計は、前記受光手段から
の強度信号に基づく信号を検量線データと比較して濃度
値に変換し出力するデータ変換手段が前記信号処理手段
に設けられていることを特徴としている。このように、
濃度値に変換されて出力されることにより、溶液中の濃
度が直接的に把握できるので、例えば異常の発生などに
もすぐに対応でき、監視作業が容易になる。In the Cr densitometer of the fifth aspect, the signal processing means is provided with a data converting means for comparing a signal based on the intensity signal from the light receiving means with the calibration curve data and converting the signal to a density value for output. It is characterized by that. in this way,
Since the concentration in the solution can be directly grasped by converting into the concentration value and outputting it, for example, occurrence of abnormality can be dealt with immediately and monitoring work becomes easy.
【００１５】請求項６のCr濃度計は、吸光度が６価クロ
ム濃度に影響されない波長の光を出射する参照光光源
と、この参照光光源から出射されて溶液を透過した後の
光を受光する参照光受光手段とがさらに設けられ、前記
信号処理手段が前記受光手段と参照光受光手段とから各
々出力される強度信号に基づいて溶液中の６価クロム濃
度に応ずる信号を出力することを特徴としている。The Cr densitometer of claim 6 receives a reference light source which emits light having a wavelength whose absorbance is not affected by the concentration of hexavalent chromium, and a light which is emitted from this reference light source and has passed through the solution. Reference light receiving means is further provided, and the signal processing means outputs a signal corresponding to the concentration of hexavalent chromium in the solution based on the intensity signals output from the light receiving means and the reference light receiving means. I am trying.
【００１６】このように参照光を用いれば、溶液中の粉
塵等による光の散乱に基づく受光手段での強度信号の低
下も、上記の参照光との比較で補正でき、これによっ
て、前述の廃液処理設備等においても信頼性の高い測定
を行うことができる。By using the reference light in this way, a decrease in the intensity signal at the light receiving means due to the scattering of light due to dust or the like in the solution can be corrected by comparison with the reference light, whereby the above-mentioned waste liquid is discharged. Highly reliable measurement can be performed even in processing equipment.
【００１７】[0017]
【発明の実施の形態】以下、図面に基づいて本発明の実
施の形態を説明する。初めに、廃液処理設備の一例につ
いて図２を参照して説明する。同図は、各種鋼材を製造
する鉄鋼製造場での廃液処理設備の構成を示している。
この廃液処理設備では、多くの表面処理工場や冷延工場
から排出される廃液を受け入れ、その中に含まれる有害
な６価クロムを無害な３価クロムに還元して沈澱させる
処理が行われる。このために、まず、受け入れ槽とし
て、６価クロム濃度が1000ppm を超える高濃度の廃液を
溜める濃厚メッキ廃水槽１と、６価クロム濃度が100ppm
程度の廃液を溜める一般メッキ廃水槽２とが設けられて
いる。濃厚メッキ廃水槽１中の廃液は、少量ずつ一般メ
ッキ廃水槽２に送られ、この廃水槽２の廃液で希釈され
て、この廃液と共に以降の処理が行われる。BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, an example of a waste liquid treatment facility will be described with reference to FIG. FIG. 1 shows a configuration of a waste liquid treatment facility in a steel plant that manufactures various steel materials.
In this waste liquid treatment facility, waste liquid discharged from many surface treatment plants and cold rolling plants is received, and harmful hexavalent chromium contained therein is reduced to harmless trivalent chromium and precipitated. For this purpose, first, as a receiving tank, a thick plating wastewater tank 1 for storing a high-concentration waste liquid having a hexavalent chromium concentration exceeding 1000 ppm, and a hexavalent chromium concentration of 100 ppm
A general plating wastewater tank 2 for storing a certain amount of waste liquid is provided. The waste liquid in the concentrated plating waste water tank 1 is sent to the general plating waste water tank 2 little by little, diluted with the waste liquid in the waste water tank 2, and further processed together with the waste liquid.
【００１８】一般メッキ廃水槽２からの廃液はまず一次
pH調整槽３に送られ、この槽３にて、後述する還元反応
促進のために硫酸が添加されてpHが２〜３程度に調整さ
れる。次いで、還元槽４に送られ、ここで、還元剤とし
ての重亜硫酸ソーダが注入され、下記の反応式に示す
ように、６価クロムが３価クロムに還元される。 4H2CrO4＋6NaHSO3 ＋3H2SO4→2Cr2(SO4)3＋3Na2SO4
＋10H2O 還元後、二次・三次pH調整槽５・６にて注入される水酸
化ナトリウム等のアルカリ剤で中和処理が行われ、下記
式で示すように、３価クロムは水に不溶性の水酸化ク
ロムとなる。First, the waste liquid from the general plating waste water tank 2 is primary.
The solution is sent to a pH adjusting tank 3 where sulfuric acid is added to promote a reduction reaction described later to adjust the pH to about 2 to 3. Next, it is sent to the reduction tank 4, where sodium bisulfite as a reducing agent is injected, and hexavalent chromium is reduced to trivalent chromium as shown in the following reaction formula. 4H 2 CrO 4 ＋ 6NaHSO 3 ＋ 3H 2 SO 4 → 2Cr 2 (SO 4 ) 3 ＋ 3Na 2 SO 4
After + 10H 2 O reduction, neutralization is performed with an alkaline agent such as sodium hydroxide injected in the secondary and tertiary pH adjusting tanks 5 and 6, and as shown by the following formula, trivalent chromium is insoluble in water. It becomes chromium hydroxide.
【００１９】 Cr2(SO4)3＋6NaOH →2Cr(OH)3＋3Na2SO4 この析出物を除去するために助剤をさらに注入して次の
沈澱槽７に送ることにより、上記の水酸化クロムはこの
沈澱槽７にて沈降分離される。沈降したクロム化合物
は、その他の亜鉛や鉄などの金属と共にスラッジ貯槽に
回収される一方、沈澱槽７の上澄水が次段の集合原水槽
に送られ、最終的な濃度の確認を行ったうえで放流され
る。Cr 2 (SO 4 ) 3 + 6NaOH → 2Cr (OH) 3 + 3Na 2 SO 4 In order to remove this precipitate, an auxiliary agent is further injected and sent to the next settling tank 7 to carry out the above-mentioned hydroxylation. Chromium is settled and separated in this settling tank 7. The sedimented chromium compound is collected in a sludge storage tank together with other metals such as zinc and iron, and the supernatant water of the sedimentation tank 7 is sent to the next collecting raw water tank to confirm the final concentration. It is released at.
【００２０】なお、上記の一次pH調整槽３と、二次・三
次pH調整槽５・６とにはそれぞれpH計８・９・10が設置
され、これらpH計８・９・10での検出値に応じて、一次
pH調整槽３への硫酸供給量、二次・三次pH調整槽５・６
へのアルカリ剤供給量が制御される。なお、還元槽４に
は還元電位計(ORP計）11が設置され、これにより、この
槽４内における還元反応の進行度合いを監視できるよう
になっている。A pH meter 8.9.10 is installed in each of the primary pH adjusting tank 3 and the secondary / tertiary pH adjusting tanks 5/6, and detection by these pH meters 8.9 / 10 is performed. Depending on the value, the primary
Supply amount of sulfuric acid to pH adjustment tank 3, secondary and tertiary pH adjustment tanks 5.6
The supply amount of the alkali agent is controlled. The reduction tank 4 is provided with a reduction potentiometer (ORP meter) 11 so that the degree of progress of the reduction reaction in the tank 4 can be monitored.
【００２１】上記した一次pH調整槽３には、さらに、廃
液中の６価クロム濃度を検出するCr濃度計30が設置され
ている。この濃度計30での検出濃度に応じて、濃厚メッ
キ廃水槽１から一般メッキ廃水槽２への廃液の送り出し
量が流量調整弁12にて行われると共に、一般メッキ廃水
槽２から一次pH調整槽３への廃液の送り出し量、すなわ
ち、単位時間当たりの廃液処理量の調整が流量調節弁13
にて行われる。さらに、上記のCr濃度計30での検出濃度
に応じて、還元剤供給ラインに介設されている流量調節
弁14の開度調整が行われ、これによって、還元槽４への
重亜硫酸ソーダの注入量が制御されるようになってい
る。The primary pH adjusting tank 3 is further provided with a Cr concentration meter 30 for detecting the concentration of hexavalent chromium in the waste liquid. In accordance with the concentration detected by the densitometer 30, the amount of waste liquid sent from the thick plating wastewater tank 1 to the general plating wastewater tank 2 is controlled by the flow control valve 12, and the primary pH adjustment tank is fed from the general plating wastewater tank 2. The adjustment of the amount of waste liquid sent to the fuel cell 3, ie, the amount of waste liquid processed per unit time, is controlled by the flow control valve 13.
Will be held in. Further, the opening degree of the flow control valve 14 provided in the reducing agent supply line is adjusted in accordance with the concentration detected by the Cr concentration meter 30, whereby the sodium bisulfite is supplied to the reducing tank 4. The injection amount is controlled.
【００２２】上記の一次pH調整槽３に流入する廃液の６
価クロム濃度は千ppm を超える広い範囲で変動する。し
たがって、この槽３に設置された前記のCr濃度計30は広
い測定範囲を備えると共に、さらに、メッキ廃液に含ま
れる亜鉛や鉄などの他の金属イオンや錯イオン等に影響
されない検出の信頼性が必要となる。このような性能を
有するべく構成されている上記のCr濃度計30での検出方
式について、以下に説明する。6 of the waste liquid flowing into the above primary pH adjusting tank 3
The chromium (VI) concentration varies over a wide range of over 1,000 ppm. Therefore, the Cr concentration meter 30 installed in the tank 3 has a wide measurement range, and furthermore, the reliability of detection is not affected by other metal ions or complex ions such as zinc and iron contained in the plating waste liquid. Is required. The detection method of the Cr concentration meter 30 configured to have such performance will be described below.
【００２３】図３は、上記した一次pH調整槽３から還元
槽４に送られてくる廃水における光の吸光度の調査結果
を示すものである。これは、図４に示すように、厚さ寸
法（光路長）ｄが例えば５mmの所定形状のガラス製の測
定セル20に廃水21を入れ、この測定セル20に照射する光
の波長を変化させたときの透過光の強度変化を測定した
ものである。また、図３に示すように、還元剤を注入す
る前の受入れ廃水、すなわち、６価クロム濃度“大”の
廃水と、濃度“中”の還元処理中の廃水と、濃度“小”
の還元処理済みの廃水との三種についての測定結果であ
る。FIG. 3 shows the results of investigation of the light absorbance of the wastewater sent from the primary pH adjusting tank 3 to the reducing tank 4 described above. This is because, as shown in FIG. 4, the wastewater 21 is put into a glass measuring cell 20 of a predetermined shape with a thickness dimension (optical path length) d of, for example, 5 mm, and the wavelength of light applied to the measuring cell 20 is changed. This is a measurement of a change in the intensity of the transmitted light when the light is applied. As shown in FIG. 3, the wastewater received before the injection of the reducing agent, that is, the wastewater having a hexavalent chromium concentration of “large”, the wastewater during the reduction treatment having a concentration of “medium”, and the wastewater having a concentration of “small”
3 shows measurement results of three types of wastewater having been subjected to reduction treatment.
【００２４】同図のように、６価クロム濃度大の廃水で
は、波長 260nm近傍と、340 〜350nm の近紫外近傍とに
それぞれ吸光度のピークを有しているが、260nm 近傍の
波長の光では、６価クロム濃度が小さくなっても他の金
属イオン等の影響が大きく、６価クロム濃度に対する吸
光度の変化はあまり認められない。これに対し、340〜3
50nm にピークを有して 500nmまでの広がりをもつ吸収
帯では、この領域に吸収帯をもつ物質が前記した廃液処
理設備での廃液中には含まれないことから、６価クロム
濃度のみに対応した吸光度変化が現れている。As shown in the figure, in the wastewater with a large concentration of hexavalent chromium, there are absorbance peaks near the wavelength of 260 nm and near the ultraviolet region of 340 to 350 nm. Even if the concentration of hexavalent chromium decreases, the influence of other metal ions and the like is large, and changes in the absorbance with respect to the concentration of hexavalent chromium are not so much recognized. In contrast, 340-3
In the absorption band having a peak at 50 nm and extending up to 500 nm, the substance having an absorption band in this region is not contained in the waste liquid in the waste liquid treatment facility described above, and therefore, corresponds only to the hexavalent chromium concentration. The change in absorbance appears.
【００２５】そこで、前記のCr濃度計30では、上記の吸
収帯での吸光度変化を検出してCr濃度を測定することを
前提に、さらに、測定濃度範囲を０から数千ppm まで広
げるために、ピーク波長域340 〜350nm からずらして、
波長450nm の青色光で廃水中の６価クロム濃度を検出す
る方式を採用し、上記波長にピークを有する高輝度の青
色発光ダイオードを第１光源（以下、青LED ともいう）
として用いている。Therefore, in the Cr concentration meter 30 described above, on the premise that the Cr concentration is measured by detecting the change in absorbance in the above absorption band, in order to further widen the concentration range to be measured from 0 to several thousands ppm, , Shifted from the peak wavelength range of 340 to 350 nm,
A method of detecting hexavalent chromium concentration in wastewater with blue light having a wavelength of 450 nm is adopted, and a high-luminance blue light emitting diode having a peak at the above wavelength is used as a first light source (hereinafter also referred to as a blue LED).
Used as.
【００２６】さらに、廃水中には粉塵等も含まれてお
り、これによって廃水中を透過する光が散乱し透過光強
度の低下が生じることから、これによる精度の低下を防
止するために、さらに参照光を別途照射する二色検出方
式を採用している。この参照光は、図３に示されている
ように、500nm 以上の波長の光では、６価クロム濃度の
変化に吸光度が影響されないことから、波長850nm の近
赤外域の光を参照光として採用し、この波長域にピーク
を有する発光ダイオードを第二光源（以下、赤LED とも
いう）として用いている。Further, the wastewater also contains dust and the like, which causes the light transmitted through the wastewater to be scattered and the transmitted light intensity to be lowered. A two-color detection method that separately illuminates the reference light is used. As shown in FIG. 3, since the absorbance of the light having a wavelength of 500 nm or more is not affected by a change in the concentration of hexavalent chromium as shown in FIG. 3, light in the near infrared region having a wavelength of 850 nm is used as the reference light. A light emitting diode having a peak in this wavelength region is used as a second light source (hereinafter, also referred to as a red LED).
【００２７】図５に、上記した青LED と赤LED との各発
光スペクトル分布を示す。さらに、前記の廃水処理設備
ではCr濃度計30が屋外で使用されることが前提であり、
このとき、図６に示すように、さらに外乱光が上記各光
源からの光に混入するおそれがある。そこで、この外乱
光による検出精度の低下を防止するため、赤LED には10
kHz 、青LED には３kHz の高周波電源をそれぞれ印加し
て点滅させ、これら点滅光の透過光強度をそれぞれ検出
する方式を採用している。FIG. 5 shows the emission spectrum distributions of the blue LED and the red LED described above. Furthermore, in the wastewater treatment equipment, it is assumed that the Cr concentration meter 30 is used outdoors,
At this time, as shown in FIG. 6, there is a possibility that disturbance light is further mixed into the light from each of the light sources. Therefore, to prevent the detection accuracy from deteriorating due to the disturbance light, the red LED
A 3 kHz high-frequency power supply is applied to each of the blue and blue LEDs to make them blink, and the transmitted light intensity of these blinking lights is detected.
【００２８】図７に、上記各方式を採用して構成したCr
濃度計30のセンサヘッド部31を示している。このセンサ
ヘッド部31は、投光ハウジング32と受光ハウジング33と
を備え、両ハウジング32・33は、同図(b) に示すよう
に、略水平なベース板34上に所定の間隔を置いて固定さ
れている。直方体ブロック形状の投光ハウジング32に
は、受光ハウジング33側の外壁面から内方に略水平に凹
入する凹入穴32ａが形成されており、この凹入穴32ａの
内方端に、投光手段を構成する前記した第１光源（青LE
D)35と、参照光光源としての第２光源（赤LED)36とが配
設されている。FIG. 7 shows a Cr formed by adopting each of the above methods.
2 shows a sensor head unit 31 of the densitometer 30. The sensor head section 31 includes a light emitting housing 32 and a light receiving housing 33. The two housings 32 and 33 are spaced apart from each other at a predetermined interval on a substantially horizontal base plate 34, as shown in FIG. Fixed. The light projecting housing 32 having a rectangular parallelepiped block shape is formed with a recessed hole 32a which is recessed substantially horizontally from the outer wall surface on the side of the light receiving housing 33, and the inner end of the recessed hole 32a is projected. The aforementioned first light source (blue LE
D) 35 and a second light source (red LED) 36 as a reference light source are provided.
【００２９】これら光源35・36は、各々の光の出射方向
を受光ハウジング33側に水平に向けて、相隣接させて固
定されている。そして、受光ハウジング33側の外壁面に
は、上記凹入穴32ａの開口端を覆うように透明な石英ガ
ラス37が気密に取付けられている。さらに、上記凹入穴
32ａ内には、石英ガラス37の内側に集光レンズ38が配設
され、この集光レンズ38により、両光源35・36から出射
される光がほぼ平行光になって、受光ハウジング33側へ
と出射される。The light sources 35 and 36 are fixed adjacent to each other so that the light emitting directions thereof are oriented horizontally toward the light receiving housing 33. A transparent quartz glass 37 is hermetically attached to the outer wall surface on the light receiving housing 33 side so as to cover the opening end of the concave hole 32a. Furthermore, the recessed hole
A condenser lens 38 is disposed inside the quartz glass 37 in the inside 32a, and the condenser lens 38 transforms the light emitted from both light sources 35 and 36 into substantially parallel light, and moves the light to the light receiving housing 33 side. Is emitted.
【００３０】一方、投光ハウジング32よりも形状を大き
くして形成されている受光ハウジング33は、同図(a) に
示すように、側壁板33ａにシールパッキン33ｂを介して
箱形容器33ｃを組み付けて構成され、全体がほぼ直方体
形状をなすように形成されている。そして、同図(b) に
示すように、投光ハウジング32に対面する壁面には、そ
の底部側に、前記凹入穴32ａと同軸状の貫通穴33ｄが穿
設されており、この貫通穴33ｄの開口端を覆うように上
記の壁面に沿って透明な石英ガラス39が気密に取付けら
れている。また、貫通穴33ｄ内に、順次、散乱板40と集
光レンズ41とが配設されている。On the other hand, the light-receiving housing 33, which is formed to have a shape larger than that of the light-transmitting housing 32, has a box-shaped container 33c mounted on a side wall plate 33a via a seal packing 33b, as shown in FIG. It is assembled and formed so that the whole has a substantially rectangular parallelepiped shape. As shown in FIG. 2B, a through hole 33d coaxial with the recessed hole 32a is formed in the bottom surface of the wall surface facing the light emitting housing 32. A transparent quartz glass 39 is hermetically attached along the wall surface so as to cover the opening end of 33d. Further, a scattering plate 40 and a condenser lens 41 are sequentially disposed in the through hole 33d.
【００３１】受光ハウジング33の内部には、その底部側
に、上記の壁面に内側から接する受光部ブロック42が固
定されている。この受光部ブロック42には、上記貫通穴
33ｄと同軸上を水平に貫通する水平穴42ａと、この水平
穴42ａの中途位置から上方に貫通する垂直穴42ｂとが形
成されている。そして、両穴42ａ・42ｂの交差位置にハ
ーフミラー43が設けられると共に、両穴42ａ・42ｂの各
開口端に、それぞれホトダイオードから成る受光手段と
しての第１受光素子44と、参照光光源としての第２受光
素子45とが取付けられている。これにより、投光ハウジ
ング32側から石英ガラス39を通して受光ハウジング33内
に入射する光は、散乱板40と集光レンズ41とを順次透過
した後、ハーフミラー43を透過してそのまま水平に直進
する光と、ハーフミラー43で反射して上方に向かう光と
に分割され、一方の光は第１受光素子44に、他方の光は
第２受光素子45にそれぞれ入射するようになっている。Inside the light-receiving housing 33, a light-receiving block 42 is fixed on the bottom side thereof so as to come into contact with the wall surface from the inside. This light receiving section block 42 has
A horizontal hole 42a penetrating horizontally on the same axis as 33d, and a vertical hole 42b penetrating upward from an intermediate position of the horizontal hole 42a are formed. A half mirror 43 is provided at the intersection of the two holes 42a and 42b, and at each opening end of the two holes 42a and 42b, a first light receiving element 44 as a light receiving means composed of a photodiode and a reference light source as a light source. The second light receiving element 45 is attached. Accordingly, light that enters the light-receiving housing 33 from the light-emitting housing 32 side through the quartz glass 39 sequentially passes through the scattering plate 40 and the condensing lens 41, then passes through the half mirror 43, and proceeds straight as it is horizontally. The light is split into light and light that is reflected by the half mirror 43 and travels upward. One light is incident on the first light receiving element 44 and the other light is incident on the second light receiving element 45.
【００３２】なお、第１受光素子44の前面には赤外光カ
ットフィルタ46が設けられており、これによって、第１
受光素子44には、前記青色発光ダイオードから成る第１
光源35からの光が入射し、その入射光の強度に応じた信
号を出力する。一方、第２受光素子45の前面には可視光
カットフィルタ47が設けられ、これにより、第２受光素
子45には赤外光発光ダイオードから成る第２光源36から
の光が入射し、その入射光の強度に応じた信号を出力す
る。An infrared light cut filter 46 is provided on the front surface of the first light receiving element 44.
The light receiving element 44 includes a first light emitting diode including the blue light emitting diode.
Light from the light source 35 is incident, and outputs a signal corresponding to the intensity of the incident light. On the other hand, a visible light cut filter 47 is provided on the front surface of the second light receiving element 45, whereby light from the second light source 36 composed of an infrared light emitting diode is incident on the second light receiving element 45, A signal corresponding to the light intensity is output.
【００３３】一方、受光ハウジング33内における上部側
には、後述する高周波電源等を構成する回路素子が組み
付けられた回路基板48が配設されている。なお、この受
光ハウジング33および前記投光ハウジング32の各上端面
にはそれぞれ防水コードコネクタ49・50が取付けられ、
これらコネクタ49・50を通して上方に延びる防水コード
51・52を介して、外部からの電源の供給や検出信号の出
力が行われる。また、受光ハウジング33における前記石
英ガラス39上部の壁面に、このセンサヘッド部31の全体
を、前記した一次pH調整槽３の廃液中に浸漬させ、所定
の高さ位置で保持するための上方に延びる操作パイプ53
が取付板54を介して固定されている。On the other hand, on the upper side inside the light receiving housing 33, a circuit board 48 on which circuit elements constituting a high frequency power source and the like, which will be described later, are assembled is arranged. In addition, waterproof cord connectors 49 and 50 are attached to the upper end surfaces of the light receiving housing 33 and the light emitting housing 32, respectively.
Waterproof cord extending upward through these connectors 49/50
External power supply and detection signal output are performed via 51 and 52. Further, the entire sensor head portion 31 is immersed in the waste liquid of the primary pH adjusting tank 3 on the wall surface above the quartz glass 39 in the light-receiving housing 33, and the sensor head portion 31 is placed above in order to hold it at a predetermined height position. Extended operation pipe 53
Are fixed via a mounting plate 54.
【００３４】このように、上記のセンサヘッド部31は、
その全体を廃液中に浸漬させて６価クロム濃度の測定を
行う浸漬型として構成されている。このため、各ハウジ
ング32・33はそれぞれ水密構造で作製され、さらに、内
蔵する各光学部品に結露を生じないように、シリカゲル
などの乾燥剤を封入して構成されている。なお、上記構
成のセンサヘッド部31の具体的な形状寸法を例示すれ
ば、図中Ｌで示す長さ寸法は 120mm、Ｗで示す幅寸法は
70mm、Ｈで示す高さ寸法は 135mmであり、また、前記し
た両石英ガラス37・39間の距離、すなわち、廃液中の光
路長ｄは５〜15mmに設定されている。As described above, the sensor head portion 31 is
The whole is immersed in a waste liquid to measure the hexavalent chromium concentration and is configured as an immersion type. For this reason, each of the housings 32 and 33 is manufactured in a water-tight structure, and is further configured to enclose a desiccant such as silica gel so as to prevent dew condensation from occurring in each built-in optical component. In addition, if the specific shape and dimensions of the sensor head unit 31 having the above configuration are shown as examples, the length indicated by L in the figure is 120 mm, and the width indicated by W is
The height dimension indicated by 70 mm and H is 135 mm, and the distance between the two quartz glasses 37 and 39, that is, the optical path length d in the waste liquid is set to 5 to 15 mm.
【００３５】受光ハウジング33内の前記回路基板48に
は、図１に示すように、3kHz電源61や10kHz 電源62等を
構成する回路素子が組み付けられている。外部から供給
される商用電源が、これら高周波電源61・62により、各
々、所定の発光ダイオード動作電圧に降圧されると共に
高周波電圧に変換され、第１・第２光源35・36に印加さ
れる。これにより、前述したように、第１光源35からは
3kHzで点滅する青色光が、また、第２光源36からは10kH
z で点滅する赤外光がそれぞれ出射される。As shown in FIG. 1, circuit elements constituting a 3 kHz power supply 61, a 10 kHz power supply 62, etc. are assembled on the circuit board 48 in the light receiving housing 33. Commercial power supplied from the outside is reduced to a predetermined light emitting diode operating voltage and converted to a high frequency voltage by the high frequency power supplies 61 and 62, respectively, and applied to the first and second light sources 35 and 36. Thereby, as described above, the first light source 35
Blue light blinking at 3 kHz, and 10 kHz from the second light source 36
Infrared light blinking at z is emitted.
【００３６】これら出射光は、それぞれ第１受光素子44
・第２受光素子45に入射し、入射光の強度に応じた信号
が各受光素子44・45から出力される。そして、これら出
力信号は信号処理装置（信号処理手段）63に送られる。
この信号処理装置63には、第１・第２バンドパスフィル
タ64・65が設けられている。第１バンドパスフィルタ64
は、第１受光素子44からの出力信号における3kHzの周波
数成分を通過させるものであり、したがって、このフィ
ルタ64通過後の信号Ａは、第１光源35から出射されて廃
液中を透過してきた光の強度に対応した信号となり、外
乱光の影響が除去されたものとなる。同様に、第２バン
ドパスフィルタ65は、第２受光素子45からの出力信号に
おける10kHz の周波数成分を通過させ、したがって、こ
のフィルタ65通過後の信号Ｂは、第２光源36から出射さ
れて廃液中を透過してきた光の強度に対応した信号とな
る。The emitted light is emitted from the first light receiving element 44, respectively.
The light enters the second light receiving element 45, and a signal corresponding to the intensity of the incident light is output from each of the light receiving elements 44 and 45. These output signals are sent to a signal processing device (signal processing means) 63.
The signal processing device 63 includes first and second bandpass filters 64 and 65. First bandpass filter 64
Is for passing the frequency component of 3 kHz in the output signal from the first light receiving element 44. Therefore, the signal A after passing through the filter 64 is the light emitted from the first light source 35 and transmitted through the waste liquid. Is obtained, and the influence of disturbance light is removed. Similarly, the second band-pass filter 65 passes the frequency component of 10 kHz in the output signal from the second light receiving element 45. Therefore, the signal B after passing through the filter 65 is emitted from the second light source 36 to be a waste liquid. The signal corresponds to the intensity of the light transmitted through the inside.
【００３７】これら両信号Ａ・Ｂから、廃液中の６価ク
ロム濃度Ｃが算出される。すなわち、第１光源35から出
射される青色光の強度をＳ、廃液中の光路長をｄとする
と、信号Ａについては、 log(Ａ／Ｓ）＝−εＣｄ ここで、ε：モル吸光係数 の関係が成立する。From these signals A and B, the hexavalent chromium concentration C in the waste liquid is calculated. That is, assuming that the intensity of the blue light emitted from the first light source 35 is S and the optical path length in the waste liquid is d, for the signal A, log (A / S) = − εCd, where ε: molar extinction coefficient The relationship is established.
【００３８】一方、第２光源36から出射される赤外光の
強度Ｒと、これが廃液を通過後に第２受光素子45で検出
されるときの強度Ｂとの間には、廃液中の６価クロム濃
度Ｃには影響されずに、廃液中の光路長ｄに依存して減
衰する関係式が導かれ、これらから、結局、６価クロム
濃度Ｃが、 Ｃ＝k1＋k2・log(Ａ／Ｂ） ……(1) 但し、k1,k2 は定数 で算出される。On the other hand, between the intensity R of the infrared light emitted from the second light source 36 and the intensity B when it is detected by the second light receiving element 45 after passing through the waste liquid, the hexavalent value in the waste liquid is obtained. A relational expression that is dependent on the optical path length d in the waste liquid and is attenuated without being influenced by the chromium concentration C is derived. From these, in the end, the hexavalent chromium concentration C is C = k1 + k2 · log (A / B) (1) However, k1 and k2 are calculated by constants.
【００３９】上記(1) 式に基づく演算を行うように、前
記の信号処理装置63に、各フィルタ64・65を通過した信
号Ａ・Ｂの比Ａ／Ｂを演算する割算器66と、その出力信
号の対数を演算して(1) 式に基づく計算を行う対数変換
器67とが設けられている。この対数変換器67から、廃液
中の６価クロム濃度に対応した電圧信号Voが出力され
る。図８には、この電圧信号（以下、センサ出力とい
う）Voと、６価クロム濃度との関係を測定した結果を示
している。同図のように、センサ出力Voは、０ppmから5
00ppm程度まで急峻な変化を示した後、さらに濃度が上
昇すると変化勾配が徐々に緩やかになるが、4000ppm を
超えるまで、センサ出力Voは６価クロム濃度の上昇に伴
って漸増する。したがって、０〜4000ppm の広い範囲に
わたって、センサ出力Voから６価クロム濃度を一義的に
求めることが可能となっている。In order to perform the calculation based on the above equation (1), the signal processing device 63 is provided with a divider 66 for calculating the ratio A / B of the signals A and B passed through the filters 64 and 65, respectively. A logarithmic converter 67 for calculating the logarithm of the output signal to perform the calculation based on the equation (1) is provided. The logarithmic converter 67 outputs a voltage signal Vo corresponding to the concentration of hexavalent chromium in the waste liquid. FIG. 8 shows the result of measuring the relationship between this voltage signal (hereinafter referred to as sensor output) Vo and the concentration of hexavalent chromium. As shown in the figure, the sensor output Vo changes from 0 ppm to 5
After showing a steep change to about 00 ppm, when the concentration further increases, the change gradient gradually becomes gentler, but the sensor output Vo gradually increases with an increase in the hexavalent chromium concentration until the concentration exceeds 4000 ppm. Therefore, it is possible to uniquely determine the hexavalent chromium concentration from the sensor output Vo over a wide range of 0 to 4000 ppm.
【００４０】そこで、図１に示すように、上記信号処理
装置63には、図８に示したセンサ出力−濃度曲線に対応
する検量線データを０〜4000ppm の範囲にわたって記憶
する記憶装置68と、データ変換手段としての濃度データ
換算器69とがさらに設けられている。この濃度データ換
算器69では、対数変換器67から出力されるセンサ出力Vo
を所定のサンプリング時間毎に上記の検量線データと比
較し、濃度値Ｃとしてデジタル値に変換して出力する。Therefore, as shown in FIG. 1, the signal processing device 63 has a storage device 68 for storing the calibration curve data corresponding to the sensor output-concentration curve shown in FIG. 8 over a range of 0 to 4000 ppm. A concentration data converter 69 as data conversion means is further provided. In this concentration data converter 69, the sensor output Vo output from the logarithmic converter 67
Is compared with the above-mentioned calibration curve data at every predetermined sampling time, converted into a digital value as a density value C and output.
【００４１】なお、図９は、同一廃液、もしくは、各種
濃度で作製した６価クロム溶液について、上記のCr濃度
計30で測定し出力された濃度値Ｃと化学分析値（手分析
値）との関係を調べたもので、図中、■は前記一次pH調
整槽３の廃液中に浸漬して得られたオンラインデータ、
○は、特に高濃度の範囲にわたって作製した６価クロム
溶液について得られたオフラインデータである。図のよ
うに、高範囲にわたって良好な測定精度が得られてい
る。Incidentally, FIG. 9 shows the concentration value C and the chemical analysis value (hand analysis value) measured and outputted by the above Cr concentration meter 30 for the same waste liquid or hexavalent chromium solution prepared at various concentrations. In the figure, ■ indicates online data obtained by immersing in the waste liquid of the primary pH adjusting tank 3,
○ is off-line data obtained particularly for a hexavalent chromium solution prepared over a high concentration range. As shown in the figure, good measurement accuracy is obtained over a high range.
【００４２】一方、図10には、前記の信号処理装置63か
ら出力されるセンサ出力Voおよび濃度値Ｃに基づいて、
運転監視用のＣＲＴに測定結果を表示させた一例を示し
ている。図中矢示するように、上段の表におけるNo.1の
欄に、上記の濃度値Ｃに基づくデジタル表示が行われ、
下段のチャートに、センサ出力Voに基づく測定結果が連
続して表示されている。On the other hand, in FIG. 10, based on the sensor output Vo and the density value C output from the signal processing device 63,
The example which displayed the measurement result on the CRT for operation monitoring is shown. As indicated by an arrow in the figure, a digital display based on the density value C is performed in the No. 1 column in the upper table.
Measurement results based on the sensor output Vo are continuously displayed in the lower chart.
【００４３】以上の説明のように、本実施形態における
Cr濃度計30は、高輝度の青色発光ダイオード（中心波
長：450nm)と、近赤外発光ダイオード（中心波長：850n
m)とを組合せた２波長吸光度測定方式を採用して構成さ
れ、特に、６価クロム溶液の吸光度がピークになる波長
からずらして測定波長を設定することにより、広範囲の
濃度測定が可能となっている。As described above, in the present embodiment
The Cr densitometer 30 includes a high-intensity blue light emitting diode (center wavelength: 450 nm) and a near infrared light emitting diode (center wavelength: 850 n
m) and a two-wavelength absorbance measurement method are adopted. Especially, by setting the measurement wavelength so that it is shifted from the wavelength at which the absorbance of the hexavalent chromium solution peaks, it is possible to measure the concentration in a wide range. ing.
【００４４】また、光源として発光ダイオードを用いる
ことにより、軽量かつコンパクト化が可能であり、さら
に製作費の低減、耐久性の向上したものともなってい
る。すなわち、例えば紫外域近傍の波長を持つ光源とし
て通常用いられる水銀ランプでは、高電圧を必要とする
ために安全性の点から水中での使用が困難、発熱量が大
きくコンパクトにできない、光源の劣化対策が必要など
の問題が生じるが、本実施形態でのCr濃度計30ではこれ
らの問題点が解消され、特に、直接浸漬型として構成し
得ると共に、連続計測が可能となっている。さらに、光
源そのものを点滅させることで変調を行い、透過光を検
波することで外乱光の影響を除去し、精度の高い測定を
行うことが可能となっている。Further, by using a light emitting diode as a light source, it is possible to make the device lightweight and compact, and further to reduce the manufacturing cost and improve the durability. That is, for example, a mercury lamp that is usually used as a light source having a wavelength near the ultraviolet region requires a high voltage, so that it is difficult to use it in water from the viewpoint of safety, generates a large amount of heat, and cannot be compact, Although a problem such as a need for a countermeasure arises, the Cr concentration meter 30 of the present embodiment solves these problems. In particular, the Cr concentration meter 30 can be configured as a direct immersion type and can perform continuous measurement. Furthermore, the modulation is performed by blinking the light source itself, and the effect of disturbance light is removed by detecting the transmitted light, so that highly accurate measurement can be performed.
【００４５】このようなCr濃度計30が、前記の図２に示
した一次pH調整槽３に設置され、そして、Cr濃度計30で
の検出信号に基づいて、前述したように、還元槽４への
重亜硫酸ソーダの注入量が調整され、また、一次pH調整
槽３で検出される６価クロム濃度が低い場合には、例え
ば濃厚メッキ廃水槽１から一般メッキ廃水槽２への廃液
の送り出し量や、一般メッキ廃水槽２から一次pH調整槽
３への廃液の送り出し量を多くする制御、或いは逆に、
検出濃度が過大な場合には一般メッキ廃水槽２からの廃
液量を絞る制御を行う。Such a Cr densitometer 30 is installed in the primary pH adjusting tank 3 shown in FIG. 2, and based on the detection signal of the Cr densitometer 30, as described above, the reducing tank 4 is provided. When the amount of sodium bisulfite to be injected is adjusted and the concentration of hexavalent chromium detected in the primary pH adjusting tank 3 is low, for example, the waste liquid is sent from the concentrated plating waste water tank 1 to the general plating waste water tank 2. Control to increase the amount and amount of waste liquid sent from the general plating waste water tank 2 to the primary pH adjusting tank 3, or vice versa.
If the detected concentration is excessive, control is performed to reduce the amount of waste liquid from the general plating wastewater tank 2.
【００４６】これにより、処理効率が向上し、しかも、
処理能力に見合った稼働状態を維持して運転を継続する
ことが可能になる。また、従来行われていた一次pH調整
槽３の廃液の色合いを目視により高頻度に監視する作業
が不要となり省力化を図ることができる。さらに、薬剤
の過剰投入によるコストアップを抑制することが可能に
なる。As a result, the processing efficiency is improved, and moreover,
The operation can be continued while maintaining the operation state corresponding to the processing capacity. In addition, it is not necessary to frequently monitor the color of the waste liquid in the primary pH adjusting tank 3 by visual observation at a high frequency, so that labor can be saved. Further, it is possible to suppress an increase in cost due to excessive injection of the medicine.
【００４７】なお、上記の実施形態は本発明を限定する
ものではなく、本発明の範囲内で種々の変更が可能であ
る。例えば上記では、青色発光ダイオードから成る第１
光源35で投光手段を構成した例を説明したが、請求項１
記載の範囲では、例えば波長域の広い白色光源に、450n
m 近傍の光を選択的に透過させるフィルターを組み合わ
せて投光手段を構成することも可能である。この場合、
上記の光源に850nm 近傍の光を透過させるフィルターを
さらに組み合わせて、参照光光源としての機能をも兼用
させる構成とすることもできる。The above embodiments do not limit the present invention, and various modifications can be made within the scope of the present invention. For example, in the above, the first
An example in which the light source 35 constitutes the light projecting means has been described.
In the range described, for example, a white light source with a wide wavelength range, 450n
It is also possible to configure the light projecting means by combining filters that selectively transmit light near m. in this case,
It is also possible to further combine the above-mentioned light source with a filter that transmits light in the vicinity of 850 nm to have a configuration that also functions as a reference light source.
【００４８】また、上記実施形態では、信号処理装置63
における濃度データ換算器69での濃度値Ｃへの換算が、
記憶手段68に記憶されている検量線データとの比較によ
り行われるように構成したが、例えば検量線データに対
応する基準電圧が入力されているオペアンプを濃度デー
タ換算器69に設け、濃度値Ｃに対応する信号をオペアン
プを通して出力させるなどのその他の構成とすることも
可能である。In the above embodiment, the signal processing device 63
The conversion into the density value C by the density data converter 69 in
Although it is configured to perform the comparison with the calibration curve data stored in the storage means 68, for example, an operational amplifier to which the reference voltage corresponding to the calibration curve data is input is provided in the concentration data converter 69, and the concentration value C It is also possible to adopt other configurations such as outputting a signal corresponding to the above through an operational amplifier.
【００４９】また、上記のCr濃度計30は、例えば自動車
や家電部品メッキ工場などの廃液処理設備や、その他の
メッキプロセスなどにも利用することが可能であり、こ
のような場合でも、廃液処理の効率向上に大きく寄与す
ることができる。Further, the Cr concentration meter 30 described above can be used for a waste liquid treatment facility such as a plating plant for automobiles and home electric appliances, and other plating processes. Even in such a case, the waste liquid treatment can be performed. Can greatly contribute to the improvement of the efficiency.
【００５０】[0050]
【発明の効果】以上の説明のように、本発明の請求項１
のCr濃度計は、６価クロム溶液における吸光度がピーク
になる近紫外領域での波長から、青色側に偏倚した波長
を中心波長とする光を照射し、溶液中の６価クロム濃度
の変化に応じた透過光強度を検出する。これによって、
より高濃度域までの測定が可能となり、例えば０〜4000
ppm の広い測定範囲を有するCr濃度計として構成するこ
とができる。As described above, according to the first aspect of the present invention,
The Cr densitometer of irradiates the light whose center wavelength is the wavelength deviated to the blue side from the wavelength in the near-ultraviolet region where the absorbance in the hexavalent chromium solution reaches its peak, and changes the concentration of hexavalent chromium in the solution. The corresponding transmitted light intensity is detected. by this,
It is possible to measure up to a higher concentration range, for example 0 to 4000
It can be configured as a Cr densitometer having a wide measurement range of ppm.
【００５１】請求項２のCr濃度計は、青色発光ダイオー
ドから成る光源を設けて上記の光を照射させることか
ら、小形化や軽量化、さらに長寿命化が図れ、安価で取
扱いの容易な装置構成とすることができる。請求項３の
Cr濃度計は、光源からの出射光を点滅させ、この点滅光
での吸光度に基づいてCr濃度の検出を行うので、例えば
屋外で使用する場合等における外乱光の影響が防止さ
れ、この結果、より精度の高い検出を行うことができ
る。The Cr densitometer of claim 2 is provided with a light source composed of a blue light emitting diode and irradiates the above-mentioned light, so that the apparatus can be made compact, lightweight and have a long service life, and it is inexpensive and easy to handle. It can be configured. Claim 3
The Cr densitometer blinks the light emitted from the light source, and detects the Cr concentration based on the absorbance of the blinking light, so that the influence of ambient light when used outdoors, for example, is prevented, and as a result, More accurate detection can be performed.
【００５２】請求項４のCr濃度計は、投光ハウジングと
受光ハウジングとがそれぞれ水密構造で形成されている
ので、両ハウジングを例えば廃液処理槽中の廃液に直接
浸漬させて連続測定することが可能である。したがっ
て、従来の廃液処理槽等にそのまま適用できるので、運
用コストが低減されると共に操作性が向上する。特に、
光源が発光ダイオードから成る構成では、この光源を作
動させるために高電圧を印加する必要はないので、安全
性も確保される。In the Cr concentration meter according to the fourth aspect of the present invention, since the light-transmitting housing and the light-receiving housing are each formed in a watertight structure, both housings can be directly immersed in, for example, the waste liquid in the waste liquid treatment tank for continuous measurement. It is possible. Therefore, it can be applied as it is to the conventional waste liquid treatment tank and the like, so that the operation cost is reduced and the operability is improved. Especially,
In the structure in which the light source is a light emitting diode, it is not necessary to apply a high voltage to operate the light source, and therefore safety is ensured.
【００５３】請求項５のCr濃度計は、受光手段からの強
度信号に基づく信号がさらに濃度値に変換されて出力さ
れるので、溶液中の濃度が直接的に表示されることとな
り、これによって、例えば異常の発生などもすぐに把握
できるので監視作業が容易になる。請求項６のCr濃度計
は、参照光をさらに用いた濃度測定を行うので、例えば
溶液中の粉塵等による光の散乱に基づく受光手段での強
度信号の低下も、上記の参照光との比較で補正でき、こ
れによって、廃液処理設備等においても信頼性の高い測
定を行うことができる。In the Cr densitometer of the fifth aspect, since the signal based on the intensity signal from the light receiving means is further converted into the concentration value and outputted, the concentration in the solution is directly displayed. For example, since the occurrence of an abnormality can be immediately grasped, the monitoring work becomes easy. Since the Cr densitometer of claim 6 performs the concentration measurement further using the reference light, the decrease of the intensity signal in the light receiving means due to the scattering of the light by the dust in the solution is also compared with the reference light. Therefore, it is possible to perform highly reliable measurement even in a waste liquid treatment facility or the like.
【図１】本発明の一実施形態におけるCr濃度計の構成を
示すブロック図である。FIG. 1 is a block diagram showing a configuration of a Cr concentration meter according to an embodiment of the present invention.
【図２】上記Cr濃度計が設置された廃液処理設備の構成
を示す模式図である。FIG. 2 is a schematic diagram showing a configuration of a waste liquid treatment facility provided with the Cr concentration meter.
【図３】上記廃液処理設備での廃液における吸光度の測
定結果を示すグラフである。FIG. 3 is a graph showing a measurement result of absorbance of a waste liquid in the waste liquid treatment facility.
【図４】上記吸光度の測定方法を示す模式図である。FIG. 4 is a schematic diagram showing a method for measuring the absorbance.
【図５】上記Cr濃度計に用いられている光源としての青
LED と赤LED との発光スペクトル分布を示すグラフであ
る。FIG. 5 shows blue as a light source used in the Cr concentration meter.
4 is a graph showing emission spectrum distributions of an LED and a red LED.
【図６】上記Cr濃度計における測定方式を説明するため
の説明図である。FIG. 6 is an explanatory diagram for explaining a measuring method in the Cr concentration meter.
【図７】上記Cr濃度計のセンサヘッド部を示すものであ
って、同図(a) は一部切欠側面図、同図(b) は一部切欠
正面図である。7A and 7B show a sensor head of the Cr concentration meter, wherein FIG. 7A is a partially cutaway side view, and FIG. 7B is a partially cutaway front view.
【図８】上記Cr濃度計におけるセンサ出力と６価クロム
濃度との関係を示すグラフである。FIG. 8 is a graph showing a relationship between a sensor output and a hexavalent chromium concentration in the Cr concentration meter.
【図９】上記Cr濃度計からの出力値と化学分析値（手分
析値）との関係を示すグラフである。FIG. 9 is a graph showing a relationship between an output value from the Cr concentration meter and a chemical analysis value (manual analysis value).
【図１０】上記Cr濃度計からの出力に基づくＣＲＴでの
表示例を示す説明図である。FIG. 10 is an explanatory diagram showing a display example on a CRT based on an output from the Cr concentration meter.
【図１１】従来の６価クロム濃度の測定方法を説明する
ための模式図である。FIG. 11 is a schematic diagram for explaining a conventional method for measuring hexavalent chromium concentration.
30 Cr濃度計 32 投光ハウジング 33 受光ハウジング 35 第１光源（投光手段） 36 第２光源（参照光光源） 44 第１受光素子（受光手段） 45 第２受光素子（参照光受光手段） 61 3kHz電源（高周波電源） 63 信号処理装置（信号処理手段） 64 第１バンドパスフィルタ 69 濃度データ換算器（データ変換手段） 30 Cr concentration meter 32 Light emitting housing 33 Light receiving housing 35 First light source (light emitting means) 36 Second light source (reference light light source) 44 First light receiving element (light receiving means) 45 Second light receiving element (reference light receiving means) 61 3kHz power supply (high frequency power supply) 63 Signal processing device (signal processing means) 64 First bandpass filter 69 Density data converter (data conversion means)
Claims (6)
になる近紫外領域での波長から青色側に偏倚した波長を
中心波長とする光を出射する投光手段と、 投光手段から出射されて溶液を透過した光を受光する受
光手段と、 受光手段から受光量に応じて出力される強度信号に基づ
き溶液中の６価クロム濃度に応ずる信号を出力する信号
処理手段とを備えていることを特徴とするＣｒ濃度計。1. A light projecting means for emitting light having a center wavelength at a wavelength deviated from the wavelength in the near-ultraviolet region where the absorbance in a hexavalent chromium solution reaches a peak to a blue side, and a solution emitted from the light projecting means. And a signal processing unit that outputs a signal corresponding to the concentration of hexavalent chromium in the solution based on the intensity signal output from the light receiving unit according to the amount of received light. Cr concentration meter.
ｍを中心波長とする光を出射する青色発光ダイオードか
ら成ることを特徴とする請求項１記載のＣｒ濃度計。2. The light source provided in the light projecting means is 450 n
The Cr densitometer according to claim 1, comprising a blue light emitting diode that emits light having a center wavelength of m.
数の高周波電圧を印加して出射光を点滅させる高周波電
源が設けられると共に、受光手段からの強度信号から上
記周波数成分の信号を抽出するバンドパスフィルタが前
記信号処理手段に設けられていることを特徴とする請求
項１又は２記載のＣｒ濃度計。3. A light source provided in the light projecting means is provided with a high frequency power source for applying a high frequency voltage of a predetermined frequency to blink the emitted light, and extracts the signal of the frequency component from the intensity signal from the light receiving means. The Cr densitometer according to claim 1 or 2, wherein a bandpass filter is provided in the signal processing means.
光手段を収納する受光ハウジングとが所定の間隔で配置
されると共に、これら両ハウジングがそれぞれ水密構造
で形成されていることを特徴とする請求項１、２又は３
記載のＣｒ濃度計。4. A light projecting housing for housing the light projecting means and a light receiving housing for housing the light receiving means are arranged at a predetermined interval, and both housings are formed in a watertight structure. Claim 1, 2 or 3
The described Cr densitometer.
号を検量線データと比較して濃度値に変換し出力するデ
ータ変換手段が前記信号処理手段に設けられていること
を特徴とする請求項１、２、３又は４記載のＣｒ濃度
計。5. The signal processing means is provided with data conversion means for comparing a signal based on an intensity signal from the light receiving means with calibration curve data and converting the signal to a density value for output. Cr concentration meter according to 1, 2, 3 or 4.
波長の光を出射する参照光光源と、この参照光光源から
出射されて溶液を透過した後の光を受光する参照光受光
手段とがさらに設けられ、前記信号処理手段が前記受光
手段と参照光受光手段とから各々出力される強度信号に
基づいて溶液中の６価クロム濃度に応ずる信号を出力す
ることを特徴とする請求項１、２、３、４又は５記載の
Ｃｒ濃度計。6. A reference light source for emitting light having a wavelength whose absorbance is not affected by the concentration of hexavalent chromium, and a reference light receiving means for receiving the light emitted from this reference light source and after passing through the solution. The signal processing means is provided, and outputs a signal corresponding to the concentration of hexavalent chromium in the solution based on the intensity signals output from the light receiving means and the reference light receiving means, respectively. The Cr concentration meter according to 3, 4, or 5.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7209769A JP3063962B2 (en) | 1995-08-17 | 1995-08-17 | Cr concentration meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7209769A JP3063962B2 (en) | 1995-08-17 | 1995-08-17 | Cr concentration meter |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP35783697A Division JPH10148612A (en) | 1997-12-25 | 1997-12-25 | Sensor head |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0954036A true JPH0954036A (en) | 1997-02-25 |
| JP3063962B2 JP3063962B2 (en) | 2000-07-12 |
Family
ID=16578315
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7209769A Expired - Fee Related JP3063962B2 (en) | 1995-08-17 | 1995-08-17 | Cr concentration meter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3063962B2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000171395A (en) * | 1998-12-02 | 2000-06-23 | Matsushita Electric Ind Co Ltd | Detector for substance dissolved in water and method for measuring substance dissolve in water |
| KR101484521B1 (en) * | 2014-07-02 | 2015-01-20 | 길주형 | Luminescent-Based Dissolved Oxygen Sensor |
| KR101493645B1 (en) * | 2013-03-07 | 2015-02-13 | 이영환 | Optical dissolved oxygen sensor for safeguarding sensor membrane |
| JP2017020903A (en) * | 2015-07-10 | 2017-01-26 | 協和メデックス株式会社 | Detection device and analysis device |
| WO2023204236A1 (en) * | 2022-04-19 | 2023-10-26 | ニプロ株式会社 | Fluid concentration measuring device |
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| JP2000171395A (en) * | 1998-12-02 | 2000-06-23 | Matsushita Electric Ind Co Ltd | Detector for substance dissolved in water and method for measuring substance dissolve in water |
| KR101493645B1 (en) * | 2013-03-07 | 2015-02-13 | 이영환 | Optical dissolved oxygen sensor for safeguarding sensor membrane |
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| JP2023158929A (en) * | 2022-04-19 | 2023-10-31 | ニプロ株式会社 | Liquid concentration measuring device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3063962B2 (en) | 2000-07-12 |
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