LABORATORY AND ON-LINE METHODS FOR OZONE MEASUREMENT

Multiple technologies and methods exist for the measurement of concentration of ozone dissolved in water. The criteria for selection of a technology include desired performance, cost, measurement location, measurement range and a determination of whether laboratory or on-line monitoring is appropriate. This paper will review technologies and methods available for both laboratory and on-line measurement of dissolved oxygen in an effort to facilitate the proper selection of instrumentation.Colorimetric measurements of ozone by the DPD or Indigo methods are the commonly accepted methods for laboratory measurements for periodic monitoring of the process, or for calibration verification of on-line instruments. The Indigo method is preferred. This is an inexpensive method that does need to be performed properly to capture the actual line conditions prior to dissipation of the ozone from solution. It is important to prevent the escape of ozone during the sampling process.On-line instruments rely on amperometric methods for measurement.For either laboratory grab samples or continuous on-line measurement, obtaining a representative sample may be the greatest challenge in ozone measurements.The methods of analysis and the methods of obtaining a representative sample will be explored.