Development of a Total Residual Oxidant Sensor

We propose to develop a compact, near real-time in-stream detector capable of continuously detecting and reporting the total residual oxidant (TRO) content in the hypochlorite-enhanced seawater streams that the Navy uses for periodic biofouling control flushes. Our detector is a compact chemical sensor that monitors oxidant analytes in water using laser Raman spectroscopy employing an immersible, nonfouling inert glass fiberoptic probe. Such a sensor will provide the required input for measurement of TRO in concentrated oxidant streams made with a variety of source waters including potable water, natural seawater, and estuarine sources for future advanced desalination systems. Raman is a well known tool for chemical identification in aqueous media that provides some unique advantages for the present topic. These include: • Application to a broad range of aqueous environments • Particularly sensitive to halogen-containing analytes • Detectable through inert silica optical fibers • Water turbidity enhances scattering and detection capability • No sample preparation or extraction required • Single detector capable of monitoring multiple analytes. For these reasons we propose to develop a compact Raman unit in a configuration consistent with the specifications required to allow utilization with Navy shipboard seawater decontamination units.