Ian Pepper

Ian Pepper

University of Arizona, USA

Title: Real-Time sensing of microbial contaminants in potable water


Ian Pepper obtained his Ph.D. at the Ohio State University. He is currently a professor of environmental microbiology at the University of Arizona where he also serves as co-director of the UA Water and Energy Sustainable Technology (WEST) Center. He has published over 170 peer review publications and 8 textbooks. Dr. Pepper is a Fellow of the American Association for the Advancement of Science (AAAS); the American Society for Microbiology; the Soil Science Society of America; and the American Society of Agronomy.


Potable waters in distribution systems are vulnerable to contamination from accidental or deliberate intrusion events. Contaminants can be chemical and/or microbial, and result in adverse health effects. Therefore the time required for the detection of the contaminant determines the magnitude of the adverse public health effect. We utilized real-time sensors to detect both Escherichia coli (E. coli) and Bacillus spores in a potable water distribution system. Th e study was conducted at the University of Arizona Real-Time Sensor Lab within the UA Water Village. Two diff erent sensors were utilized. One sensor utilized multiangle laser light scattering (MALS) to detect particulates. Th e other sensor used light scattering plus fluorescence emission from nicotinamide adenine dinucleotide phosphate (NADP) and ribofl avin. Th e bacterium E. coli could be detected in distilled water or tap water in real-time over a concentration range of 106 CFU per ml -103 CFU per ml. In contrast, Bacillus thuringiensis, a surrogate for Bacillus anthracis was used as a source of bacterial spores, which would be detected in real time over a concentration range of 105 per ml - 102 per ml. Th e sensors were also utilized to document the absence of viable E. coli cells following advanced oxidation treatment of the water via ultraviolet light and hydrogen peroxide. Thus, these sensors could be utilized in real-time to either detect microbial contaminants, or document the destruction of microbial contaminants. In either case, such sensors could verify the safety of potable water, with respect to potential microbial contaminants.

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