Water reuse: innovative monitoring technologies for risk reduction

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As global change influences the availability and quality of drinking water sources, greater numbers of communities around the world are turning to wastewater reuse to satisfy their water supply needs. Although water reuse is an important potential drinking water source for arid or semi-arid regions where the demand can exceed available supplies, the sprawl of large urban metropolitan areas in humid climates has frequently led to de facto or unplanned indirect wastewater reuse. Although wastewaters contain a wide suite of environmental contaminants, human pathogens remain a priority. Traditionally, routine monitoring of culturable fecal indicator bacteria such as Escherichia coli have been the standard approach for assessing water quality. However, assays require a minimum of 18-24 hours before results are available for drinking water treatment plant operators or water resources managers. Thus, E. coli culture-based methods do not allow for rapid and cost-effective decision making. For water reuse, it is important to identify periods of higher risk, particularly as events leading to incomplete wastewater treatment are common (e.g. treatment bypasses, combined sewer overflows, equipment failures, planned discharges during repairs, etc.). New rapid, automated online technologies are being developed to facilitate E. coli detection in water. Samples are autonomously collected for direct measurements of ß-D-glucoronidase activity, an enzyme specific to E. coli, without a lengthy cultivation step. The time from sample collection to result is shortened from 18-24 hours to 30 minutes. This research program aims to improve the safety of source waters by ensuring greater availability of supplies while reducing the impact of unplanned water reuse on human health. The research objectives are to: 1) evaluate the current state of water reuse in Canada, 2) develop a novel toolset for rapid assessment of water quality to improve safety, 3) create a new approach for monitoring planned and unplanned water reuse during normal operation and during events, and 4) propose a new risk-based strategy for managing water reuse in drinking water sources while considering the impact of global change. The novel and innovative technologies will be installed at field sites that are good examples of unplanned water reuse. Devices will measure E. coli dynamics at a fine temporal resolution to identify, characterize and predict peak E. coli concentrations in the source water and through drinking water treatment. As more communities turn to water reuse for water supply, there is a need to understand and mitigate human health risks and to propose regulatory or monitoring frameworks to set water quality criteria and ensure that they are met. Seven graduate students and 5 undergraduate students will be trained in state of the art technologies applicable to urban water management in support of new policies for healthier communities.