A new treatment plant in Orange County, Calif., is one of about 15 in the country to recycle wastewater back into the groundwater drinking water supply -- a plan called indirect potable reuse. Two experts answer your questions on water recycling.
Does this system remove pharmaceuticals from wastewater?
Michael Snider of Napa, Calif. asks
Napa is discussing distributing treated water back to the town, and the topic of excreted pharmaceuticals has become of concern. My question is, if one wishes to remove most (or all) drug-like compounds, what additional steps would be required?
Shivaji Deshmukh responds:
More sensitive analytical measurements have allowed water agencies recently to find the presence of pharmaceuticals in water at very low trace levels. Orange County Water District began testing for pharmaceuticals in anticipation of the Groundwater Replenishment System beginning operation in 2008.
Water purified by the Groundwater Replenishment System contains no detectable pharmaceuticals. Reverse osmosis has been proven to remove pharmaceuticals.
It is important to note that detection methods are still being developed and as they are, water will be tested to ensure that safe levels remain. Currently, researchers do not believe that there is any human health risk from the extremely low trace levels of pharmaceuticals in water, but research into this question is continuing.
Cheryl McGovern responds:
The Orange County Groundwater Replenishment System project uses advanced wastewater purification processes, including microfiltration, reverse osmosis, ultraviolet light and hydrogen peroxide to treat wastewater. The resulting product meets state and federal drinking water standards before returning to the groundwater basin via infiltration through soil that has been demonstrated to effectively remove such compounds.
EPA has been funding research on the effects and treatment of chemicals related to excreted pharmaceuticals. One study released last summer by the American Water Works Association Research Foundation confirms that these chemicals can be removed through currently available treatment methods. The report is titled "Removal of EDCs and Pharmaceuticals in Drinking and Reuse Treatment Processes," by Snyder, Wert, and Lei (Southern Nevada Water Authority) and Westerhoff and Yooz (Arizona State University).
The conclusion of their study is that endocrine disrupting chemicals (EDCs) and pharmaceuticals and personal care products as pollutants (PPCPs) occur in U.S. drinking water only at minute concentrations so it is highly unlikely that most of these chemicals will pose any credible threat to human health via drinking water exposure. They further recommend regulatory agencies consider human health protection, and not simply trace occurrences, in establishing subsequent monitoring requirements and regulatory limits. They suggest future research should focus on determining the toxicological significance of trace occurrence of various contaminants to establish sensible analytical detection limits and treatment goals.