A webcast presenting the results of a project to develop tools to evaluate indirect potable water reuse (IPR) is being held by the WateReuse Research Foundation on 12 April 2012.
The project developed information and tools to evaluate the use of reclaimed water for IPR in terms of:
1. Quantitative relative risk assessments
2. Screening level exposure concentrations and risk metrics for constituents of emerging concern (CECs)
3. New pharmaceuticals and their ability to persist after treatment
4. An expert elicitation tool to capture professional judgment.
Speakers Margaret H Nellor of Nellor Environmental Associates Inc and Jeffrey Soller of Soller Environmental LLC will report that the study’s results have practical applications.
The quantitative relative risk assessment (QRRA) tools used by this study can be applied by agencies that wish to pursue groundwater recharge and surface water augmentation projects using available monitoring data. The results can be used to assess risks, focus on specific source control and/or treatment options, and provide information for the regulatory decision resource-intensive and costly health-effects studies.
The results of the QRRA were also presented in the National Research Council report Water Reuse: Potential for Expanding the Nation’s Water Supply Through Reuse of Municipal Wastewater .
The drinking water benchmark and risk metric approach used for CECs allows agencies to focus on possible source control actions or treatment modifications for chemicals where potential risks may be of concern. It also allows agencies potentially to avoid expenditures or strategically to direct resources when dealing with new chemicals by establishing water benchmark thresholds.
The results of this project included a number of important findings, including:
• More than 90% of the new target pharmaceuticals identified were predicted to not be persistent in IPR systems and over 95% are removed by reverse osmosis treatment
• The baseline information collected for the study could be updated to revisit the relevance of key compounds to see if they become high volume production drugs and identify new products that might be of future significance in the marketplace that warrant further investigation
• The modified QSAR model developed for the study can be applied to other compounds that may be of interest in the future to address treatability
• The expert elicitation approach could be applied to verify its promise in seeking expert opinions in lieu of more traditional, but more expensive methods.
The results of the study have been used to demonstrate the safety of two operating groundwater recharge projects that have been used to support changes to regulatory requirements and project expansion.