Evaluation of Four Dissolved Ozone Residual Meters' Performance and Disinfection Credits in Potable Reuse Applications

Measurement of dissolved ozone (O-3) residual is critical for accurately determining O-3 concentration-contact time product (CT) in order to establish pathogen removal credit. Higher concentrations of metals and organics in wastewater present more challenging conditions for on-line meters, requiring more frequent calibration and maintenance. This study evaluated the performance, maintenance, and cost of four commercially available over a 1-year period. Individual meter readings were compared to daily grab samples analyzed with an indigo trisulfonate method to determine O-3 residual. Ease of maintenance and reliability of O-3 residual measurements were key parameters in ranking the meters for monitoring ozone CT in a water reuse application.