The Thermo Scientific™ Orion™ 7070iX TRO Analyzer is designed to provide fast, accurate and reliable online detection of total residual oxidants (TRO) – optimized for applications that require low level detection of TRO. Oxidizing biocides (e.g. chlorine) are commonly used to kill pathogens in water for disinfection in many industrial applications, such as cooling towers, drinking water and tertiary wastewater treatment. The water in these processes is often treated with chlorine, chloramine, bromine or chlorine dioxide to control microbiological fouling and pathogen levels. Strict regulatory discharge permits in many countries (e.g., United States and Canada) require that chlorine levels must be monitored online and reduced below 100 ppb or less before the water can be discharged to the environment. This introduces significant challenges to accurately measuring and controlling TRO, which is a sum of all oxidizing biocides. Process control is achieved by measuring TRO online to ensure accurate dosing to control biological growth at optimal operational cost of biocides and oxygen scavengers. More importantly, the TRO levels must be low enough for discharge to comply with the local regulatory discharge permit. Current online DPD colorimetric measurement for TRO has a few limitations, such as higher detection limit, larger error at low ppb level, drift due to discoloring reagent and poor performance in sea water and other waters with interfering ions. The new Orion 7070iX TRO Analyzer with electrode sensing technology solves these issues with significantly improved detection limit and accuracy using the existing U.S. EPA approved methods.