Tosio Moriwake

A process monitoring/controlling system for the treatment of wastewater containing chromium(VI)

An advanced monitoring system for controlling the treatment process of wastewater containing chromium(VI) was developed using a flow method as a chemical sensing probe. In this system, the acquisition of monitoring information and the control of the treatment process is computer-controllable. By application of the system to control the end-point of redox-treatment, an accuracy and precision better than ±0.9% (n = 5) and a relative standard deviation smaller than 0.5% (n = 5) were found; furthermore, safe discharge of wastewater can be ensured without the addition of any coprecipitation reagents.

Determination of chemical oxygen demand by a flow-injection method using cerium(IV) sulphate as oxidizing agent

Abstract A method based on flow injection was developed for the automated determination of chemical oxygen demand (COD) that provided a number of possibilities for improvement of the limitations of the standard manual methods. The strong oxidizing agent used is cerium(IV) sulphate, which resulted in a high degree of sample oxidation under mild operating conditions. The reaction between samples and cerium(IV) ion produced a sensitive and reproducible signal, i.e., a decrease in absorbance. The detection limit and relative standard deviation of the method were 0.5 mg l −1 and 0.6% ( n = 10), respectively, for a standard sample consisting of l -glutamic acid and lactose in a ratio of 5:1. When 50-μl samples were injected at a frequency of 20 h −1 , the determination range was 0.5–130 mg l −1 COD. Chloride was tolerated up to a concentration of 30 g l −1 without any masking agents. COD values for various types of wastewater samples correlated well with those obtained by standard manual methods.

High-sensitivity flow method for the determination of proteins with micro-flow plunger pumps

Abstract In order to determine micoamounts of proteins with low molecular diffusivity, a flow method was developed by both miniaturizing the common flow-injection apparatus and using the dye association method. A very precise double-plunger micropump, which was recently developed for this purpose, was used. The optimum conditions using bovine serum albumin (BSA) as standard and some ion-association dye reagents at very low flow-rates were examined. It was shown that a flow-rate of less than 50 μl min−1 was acceptable when a short, small-bore reaction tube was used. Up to 15 samples H−1 could be analysed with a relatively long residence time; linear calibration graphs were obtained with both 8-μl volume loop valve injection and no-injection methods. The detection limit and relative standard deviation of the injection method were 0.003 μg ml−1 and 0.15%, respectively, for BSA.

WATER QUALITY MONITORING SYSTEM USING A FLOW-THROUGH SENSING DEVICE

ABSTRACT In February 1989, the technique for Flow Injection Analysis (FIA) was established by the Japanese Industrial Standard JIS K0126-1989. This chemical analysis method, which uses a flow-through process, has applications in water monitoring systems. The flow-through method involves continuous flow in a small-bore tube which facilitates the accurate sensing of the target component by using time-controlled reactions. This differs from the well-known chromatography processes which generally separate out the various components. Satisfactory results can be achieved with the application of automation technology to flow-through analysis of unspecific pollutants having a range of molecular weights such as chemical oxygen demand (COD), total phosphorus (TP), total nitrogen (TN) and organic chemicals. In the present research, the authors have developed a flow-through COD sensor using either potassium permanganate, potassium dichromate, or cerium(IV) sulphate as the oxidizing agent, and results were obtained which compared well to the official water analysis method based on a manual procedure. Even though satisfactory correlations have been found, the main problem in using the flow-through COD sensor in water monitoring is due to difficulties caused by suspended solids (SS) components in the water samples. It was found that pretreatment of the water samples was necessary, using a process such as filtration. Based on the results of these investigations, the design of the flow-through sensing device for use in practice was improved. An example of the application of the sensing device in a water quality monitoring system is given, using actual water samples.

Continous measurement of sulfate ion in environmental water samples by FIA.

酸性雨をはじめとする環境水試料の分析で求められている簡易,迅速でかつ精度の高い分析技術の装置化を目的に,流動と混合を最適に行わせるためストローク長は短いが速い往復運動をするダブルプランジャーマイクロポンプで構成された改良FIA装置を用い,微量硫酸イオンの連続計測に良好な結果を得た.水試料は2分ごとに断続的に注入できるので,硫酸イオンを1時間当たり30検体で連続計測でき,自動サンプリング装置を用いれば運転の自動化・システム化も可能であった.本法の検出限界濃度は,S/N=3で電気的に増幅した場合硫酸イオンとして0.02mg/l,精度は硫酸イオン5mg/lを含む試料溶液を10回測定した結果,相対標準偏差0.5%であった.鉛,鉄,アルミニウムなどの金属イオン共存下では,0.01M EDTA添加によりマスキングを行う必要がある.雨水,雪などのような酸性雨関連の環境水試料をはじめ,岡山県下の河川水,水道水などの各種環境水試料に本法を適用し,公定法とほぼ一致した結果を得た。このFIA装置を岡山大学環境管理センターの実験系洗浄排水貯槽に接続し,時間変化に伴う水質データ取得を試み,相関式y=1.06x-8.6,相関係数0.99を得,公定法と良好な相関関係があることを認めた.本FIA方式化学センサーシステムは更に改良を加えれば,水質の連続モニタリングや酸性雨の計測監視装置などとして利用可能な基本特性を有することが分かった.

Continuous determination of total sulfur oxide in exhaust gas by FIA.

流動・分散・混合・反応条件などの精密制御と精度・再現性の良さなどを要素技術とする細管内連続流れ系を用いたFIAは,時間と空間とから成る四次元でサンプリング可能な環境計測・モニタリングに有効である.本研究では各種燃焼排ガス中の全硫黄酸化物の定量にFIAを適用するため,バリウム-スルポナゾIII錯体を用いて実験的に検討を行い従来法を改良し,装置条件及び操作条件を確立した.過酸化水素水(1+9)を吸収液として用い,排ガス中の全硫黄酸化物の簡易測定に応用し,公定法による測定値と比較評価した結果,満足すべき相関が得られ,高感度な連続測定装置の開発が可能であることが分かった.更に,岡山大学環境管理センターの有機系廃液・廃溶媒などの燃焼処理に伴って排出される煙道排ガス中の低濃度全硫黄酸化物監視への応用を試み,連続モニタリングシステムを構築し実験的に検討し,大気観測にも応用可能な実用的装置・システム開発へ発展性を有する基礎的成果を得た.