Grantee Research Project Results
2016 Progress Report: Early Career Award: Framework for Quantifying Microbial Risk and Sustainability of Potable Reuse Systems in the United States
EPA Grant Number: R835823Title: Early Career Award: Framework for Quantifying Microbial Risk and Sustainability of Potable Reuse Systems in the United States
Investigators: Gerrity, Daniel
Institution: University of Southern California
Current Institution: University of Nevada - Las Vegas
EPA Project Officer: Packard, Benjamin H
Project Period: August 1, 2015 through July 31, 2018
Project Period Covered by this Report: August 1, 2015 through July 31,2016
Project Amount: $329,650
RFA: Human and Ecological Health Impacts Associated with Water Reuse and Conservation Practices (2014) RFA Text | Recipients Lists
Research Category: Water , Human Health
Objective:
This research addresses three critical issues related to the spectrum of potable reuse applications in the United States: (1) quantifying the microbial and chemical risks associated with various treatment trains in de facto, “planned” indirect potable reuse (IPR), and direct potable reuse (DPR) paradigms; (2) developing a framework for comparing the sustainability of IPR versus DPR; and (3) evaluating alternative treatment trains based on the formation and mitigation of conventional and emerging disinfection byproducts (DBPs) and other contaminants of emerging concern (CECs). The research is intended to demonstrate that “planned” potable reuse offers a safe and sustainable alternative to conventional drinking water practices.
Progress Summary:
The first year of the Quantitative Microbial Risk Assessment (QMRA) effort resulted in a nearly complete system dynamics model evaluating the risk of cryptosporidiosis in de facto reuse (i.e., unplanned IPR), planned IPR, and DPR systems. This initial version of the model focuses on ozone-based advanced treatment trains. The planned IPR system includes conventional wastewater treatment, ultrafiltration (UF), pre-ozonation, biological activated carbon (BAC), post-ozonation, discharge and blending in a drinking water reservoir, and conventional drinking water treatment consistent with the U.S. EPA’s Long Term 2 Enhanced Surface Water Treatment Rule (LT2). In the DPR system, the drinking water reservoir is eliminated, and the post-ozonation process is replaced with UV disinfection. The model evaluates the impact of varying operational parameters, including recycled water contribution, reservoir storage time, disinfection dosing, and process failure scenarios, on annual risk of waterborne disease. In May 2016, a project workshop attended by senior research personnel, including Dr. Joseph Eisenberg of the University of Michigan, Dr. Brian Pecson of Trussell Technologies, and Dr. Eric Dickenson of the Southern Nevada Water Authority, was held at UNLV to present the model framework and preliminary results.
A system dynamics model describing the current water system in Southern Nevada has nearly been completed. The model accounts for inflows and outflows from Lake Mead, current and future water demands, pumping requirements to meet those demands, indoor versus outdoor water use, and return flows to Lake Mead, among other “stocks” and “flows.” The model will soon be expanded to include water and wastewater treatment, including the current IPR configuration and a suitable DPR alternative. Once the model is calibrated against recent operational data, several policy alternatives will be evaluated in the context of water supply, economic cost, energy consumption, and greenhouse gas emissions to determine the viability of DPR relative to the “status quo” IPR approach.
With respect to the ozone-biofiltration system, a series of experiments was performed at ozone to total organic carbon (O3/TOC) ratios of ~0.1-2.25 and empty bed contact times (EBCTs) ranging from 5-20 minutes. Process efficacy was characterized based on changes in UV254 absorbance, TOC removal, and reductions in the concentrations of total trihalomethanes (TTHMs) and five haloacetic acids (HAA5). In addition, a general framework was developed for chlorinating secondary wastewater effluents based on TOC and ammonia concentrations to achieve a 1 mg/L free chlorine residual after 24 hours, in accordance with the uniform formation conditions (UFC) approach.
Future Activities:
The project team will extend the current system dynamics QMRA model to bacteria, viruses, and Giardia, and a treatment train employing reverse osmosis will also be incorporated into the model. We expect to submit a peer-reviewed manuscript detailing the current version of the model in the early fall. To supplement the system dynamics model, a MATLAB-based disease transmission model will be developed to evaluate the time dependency of disease transmission. We also expect to finalize the system dynamics model comparing the sustainability of IPR and DPR, and the full comparison is expected to be completed within the next reporting period. Another M.S. student will be trained in August 2016 to continue operating the pilot-scale ozone-biofiltration system to evaluate CEC mitigation.
Dr. Gerrity also will begin working with Brett Levner, who is an Assistant Professor in the UNLV Department of Film. Dr. Gerrity will assist with her Spring 2016 course on documentary filmmaking. Students in the course will be expected to “pitch” their ideas for a documentary focusing on potable reuse, specifically as it relates to the Southern Nevada water system. One or two of the most promising ideas will be approved for production. The expected outcome from the collaboration will be a short film (or films) that can be used to educate the general public about the benefits of potable reuse.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 23 publications | 3 publications in selected types | All 3 journal articles |
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Type | Citation | ||
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Amoueyan E, Ahmad S, Eisenberg JNS, Pecson B, Gerrity D. Quantifying pathogen risks associated with potable reuse: a risk assessment case study for Cryptosporidium. Water Research 2017;119:252–266. |
R835823 (2016) R835823 (2017) R835823 (Final) |
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Supplemental Keywords:
Drinking water, decision making, engineering, potable reuse system, sustainability;Relevant Websites:
EPA STAR Grant | Funded Research | Daniel Gerrity ExitResearch Files 404 | UNLV-TV Productions Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.