WateReuse Arizona Meeting & Webinar
March 15, 2019 – Section Meeting & Webinar, meeting will be held at Marana Water.
10:00 AM – 11:00 AM Webinar Presentation
11:00 AM – 11:30 AM Arizona Section Board Meeting
Kerry Hamilton, Assistant Professor, ASU’s School for Sustainable Engineering and the Built Environment and The Biodesign Institute Center for Environmental Health Engineering
Reclaimed water is a valuable resource, yet limited information is available regarding potential health risks. Legionella bacteria present a potential water quality concern in reclaimed water due to their public health importance and ability to thrive in engineered water systems. Infection is caused from inhaling or aspirating mists containing the bacteria. To inform risk management strategies, a series of stochastic quantitative microbial risk assessment (QMRA) models were developed for spray irrigation and cooling tower exposures. Risks varied depending on meteorological conditions and operational characteristics such as drift eliminator performance.
However, the greatest differences between risk scenarios were due to 1) the dose response model chosen 2) population at risk considered (residential or occupational) and 3) differences in laboratory analysis method (culture, quantitative PCR, or ethidium-monoazide-qPCR). Risks were non-trivial at potentially large setback distances under some conditions. Theoretical setback distances necessary to achieve a 1 in 10,000 annual risk are proposed. The sensitivity analysis indicated that the most influential factors for variability in risks were the concentration of Legionella and aerosol partitioning, highlighting the importance of strategies to manage Legionella occurrence in reclaimed water.