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Issue link: http://wateronline.epubxp.com/i/816402
to monitor pathogen reduction in treated water. The Beenyup Wastewater Treatment Plant and Advanced Water Recycling Plant (Perth, Australia) pilot trial identified two key solutions that could improve their process control. First, the implementation of UV254 and fluorescence online sensors may be useful additions to their system. Second, the implementation of a microbial assay like LuminUltra would allow for rapid detection of potential microbial contaminants. The Sacramento Regional Wastewater Treatment Plant (Sacramento, CA) trial found sensors useful in evaluating the treatment performance and incremental failure events during membrane filtration. The addition of a fluorescence online sensor would also potentially provide additional online process control. T h e Tu c s o n Wa t e r S w e e t w a t e r R e c h a r g e Infiltration Systems (Tucson, AZ) pilot found ozonation more effectively reduced total microbial load and MS2 levels over UV-AOP. This implies that total microbial load is an effective surrogate for pathogen reduction in treatment process trains, as it includes a broad spectrum of microorganisms that are more resistant to inactivation than human pathogens typically found in wastewater. Full-Scale Findings The full-scale evaluations occurred at facilities that currently implement potable reuse to determine the effectiveness of online monitoring systems. When combined with the laboratory and pilot-scale evaluations, recommendations for the full-scale facilities were developed to suggest ways to improve their monitoring practices. The facilities that conducted full-scale demonstrations included West Basin Municipal Water District and Orange County Water District. The results of the full-scale evaluations demonstrated that online sensors can be effective strategies for monitoring process control, and real-time monitoring can detect failures in potable reuse treatment schemes quickly and reduce the response time to rectify the problem. Based on the laboratory, pilot-scale, and full-scale evaluations, online sensors were shown to be useful for monitoring process control. Overall data from the pilot- and full-scale utility evaluations show that utilities in the U.S. and abroad do use online sensors successfully to monitor for the presence of chemical contaminants in real time, but not microbial contaminants. Currently, utilities rely heavily on sensors for turbidity, conductivity, and total organic carbon (TOC) to act as real-time triggers to alert operators of treatment failure. These sensors could usefully be augmented by an online fluorescence sensor and a real-time assay for microbial contaminants. Sensor-ability These research findings provide meta-data on a variety of different sensors including parameters such as working range, accuracy, precision, response time, and detection mechanism. In addition, the researchers evaluated the ability of different sensors to detect incremental failure of advanced treatment and the efficacy of various sensors in waters with differing water quality. Finally, the team characterized the current status of the use of online sensors at utilities nationally and internationally by evaluating operational pilot and full-scale treatment trains. Re a l - t i m e m o n i t o r i n g offers the opportunity to engage in potable reuse with the ability to detect failures quickly and greatly reduce the response time needed to rectify upsets in a treatment system. The research indicates that at the same time, the need for engineered storage in direct potable reuse would be reduced due to the faster response time in monitoring. The variety of evaluations also identified some gaps and issues in sensor technology: • Enhanced sensitivity of contaminant detection and removal via surrogates • Further development of an online sensor for bacterial microbial contaminants • Development of an online sensor for human pathogenic viruses, perhaps via aptamers or immunoassays coupled to microfluidics • Enhanced ability to detect minimal incremental failure • Development of superior software for data maintenance and setting of constantly operational alarm thresholds • Development of online courses to train utility personnel with respect to new real-time technologies, including sensor maintenance These topics are among many that may be tackled by the WE&RF; water reuse and desalination issue area team in future research efforts. n wateronline.com n Water Innovations 27 WATERQUALITYANALYSIS Justin Mattingly is a research manager at the Water Environment & Reuse Foundation focusing on treatment systems for potable reuse, industrial reuse, and water economics and finance. Prior to joining WE&RF;, he completed a four-year fellowship at the U.S. EPA in the Clean Water State Revolving Fund program, working with states and communities to develop innovative financing tools and strategies to fund a diverse array of water quality projects. Justin has a bachelor's degree in biological sciences from the University of Delaware and a master's degree in environmental science from American University. About The Author University of Arizona Sensors Lab