GOALI: Integrated Oxidation Vapor-gap Reverse Osmosis Systems for Water Reuse

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The American West is experiencing drought conditions worse than those seen in nearly a millennium. Securing reliable water supplies is therefore essential to ensuring the health and prosperity of the nation. Purifying wastewater (treated sewage) so that it can be reused as a water source is a sustainable method to increase water supplies and uses less energy than alternatives, such as making drinking water out of seawater. To be safe for consumption, wastewater must be thoroughly treated to remove all harmful contaminants, a practice that is costly and resource intensive. This research project will develop a new treatment system that combines oxidation and membrane processes to reuse wastewater more efficiently. The work will determine how wastewater contaminants are removed in a new membrane process and how using oxidation combined with membranes can further improve contaminant removal. The project will also test the ability of the new system to remove regulated compounds from actual wastewater in close collaboration with Trussell Technologies, the industrial project partner and a leader in water reuse in California. The project will build a diverse scientific workforce by training students that will work as interns at Trussell Technologies and learn about the societal importance of water reuse. Additional benefits to society will be accomplished through education and training including the mentoring of one graduate student at the University of Colorado at Boulder.Converting wastewater effluent into potable water requires a high degree of pathogen and contaminant removal, which is energy-intensive and costly. This GOALI proposal will advance a new membrane-based reuse treatment train centered on vapor-gap reverse osmosis (VGRO) integrated with strong pre-oxidation for fouling and organic micropollutant control. VGRO is an emerging process that separates constituents by volatility, allowing for near-complete rejection of non-volatile and semi-volatile contaminants poorly removed by reverse osmosis, the conventional system for removal of benchmark contaminants regulated in current reuse operations. Preliminary research on this project also indicates that the membranes used in VGRO resist degradation from strong oxidants (e.g., ozone, free chlorine), potentially overcoming a major weakness of conventional reverse osmosis membranes. The scientific objectives of the research are to (1) explore the oxidative transformation of model wastewater contaminants and how this affects their rejection in VGRO, (2) determine the impact of ozonation and chlorination on membrane properties and fouling behavior, and (3) evaluate the performance of an integrated ozonation and VGRO process against contaminant removal benchmarks while treating actual wastewater reuse influents in close collaboration with the industrial partner, Trussell Technologies. The industrial collaboration is essential for keeping the research within realistic boundaries for reuse practices and they will be co-leading tasks and mentoring students. Overall, the results of this work will advance VGRO with oxidation as a potential alternative to current costly practices in water reuse and improve the fundamental understanding of contaminant removal in oxidation and membrane systems. The project will also improve scientific literacy through an outreach program that teaches elementary school students about water using dance and art.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.