Western water utilities are looking to water re-use as a sustainable solution to meet future needs. In California, municipal wastewater is treated to a high enough degree that it can be returned to the water supply for a variety of beneficial uses (1) including landscape irrigation (2-4), agriculture (5,6), ecosystem enhancement (7), industrial cooling and processing (3, 8), ground water recharge, and indirect potable reuse (8-10). However, despite meeting national and state water quality standards set for water re-use, unregulated trace contaminants that persist in recycled water are cause for significant concern.
Among contaminants of emerging concern (CECs), a broad spectrum of chemicals suspected to cause detrimental effects on the environment at trace levels, N-nitrosodimethylamine (NDMA) is particularly noxious. It is widespread, toxic, and difficult to contain and remediate. Unlike many other CECs, the source of NDMA is often the water treatment process itself methods such as chlorine-based disinfection often lead to the accumulation of this carcinogen.
There is no effective and feasible way to completely remove NDMA from contaminated reclaimed wastewater. This is a major unsolved challenge that specifically plagues efforts to find safe uses for reclaimed treated wastewater.
This project will look at how plants cope with NDMA in contact-water, including plant uptake, accumulation, and potential bioconversion of this trace contaminant. Findings will help predict and model how food crops irrigated with contaminated reclaimed water might serve as a vehicle for human exposure to NDMA. This will aid in predicting the impact of contaminated reclaimed water on food safety and in designing remediation systems in the context of managed natural systems.
Richard Luthy Silas H. Palmer Professor of Civil Engineering