The use of on-line sensors requires extensive attention to the selection and maintenance of the instruments along with thoughtful processing and analysis of the resulting data for the on-line measurements to lead to responsible decisions. The usefulness of the data and the efforts required to increase the accuracy and precision are directly related to the intended uses of the data. The range of effective uses and challenges will be presented supported by specific case study results from a variety of US utilities.  Specific examples of data accuracy and precision will be presented along with demonstration of the improvements that can be achieved through the development of appropriate standard operating procedures for instrument maintenance and data processing. Based on the distributions observed for on-line data and the calculated accuracy and precision, power analysis were performed to determine the difference which are statistically detectable for on-line sensor data. Strategies for data aggregation that reduce variability and improve both the accuracy and the precision will be presented. Results will be presented for Chlorine Residual, Conductivity, ORP and pH.  Examples of appropriate uses of on-line data will be presented including the efficacy of on-line data for event detection based on near-real time water quality monitoring data.

On-line water quality monitors challenges and progress in producing useful data

247th National Meeting (2014)

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