Excellence in Research: A Novel High Throughput Forward Osmosis Membrane for Produced Water Treatment

Prairie View A & M University, Prairie View TX

Investigators

Abstract

Hydraulic fracturing operations for shale gas and oil production consume high volumes of fresh water eventually generating flowback water and produced water as byproducts. Much of this water is disposed of through deep-well injection which, if handled improperly, can cause environmental hazards. Ideally, produced water would instead be treated and discharged to the environment. Due to high levels of organic contaminants and various salts present in produced water, there is a lack of efficient and mature technologies for this application. Reverse osmosis is ineffective for treating produced water because the osmotic pressure caused by the high salinity repels the hydraulic pressure used in reverse osmosis. Forward osmosis is an emerging technology that is suitable for treating produced water since it is a naturally osmotic process. Forward osmosis membranes have shown promising performance for separating organic pollutants and salt from some wastewater and for treating produced water at high salinity. However, to apply forward osmosis technologies to produced water treatment at the industrial scale, there are technical challenges that must be addressed, including: (1) relatively low flux of commercially available forward osmosis membranes, (2) membrane fouling caused by deposition of organic matter during forward osmosis, and (3) ammonia loss from the water feeding side of the membrane when ammonia-carbon dioxide is used as draw solute in the forward osmosis process. The project will develop a unique dual-skinned forward osmosis membrane designed to overcome these challenges. Computational modeling will be applied to describe the mechanisms by which flux is improved and fouling is mitigated. Research and education will be integrated through educational activities and training of undergraduate and graduate students. These activities will prepare students to become community-engaged scholars as well as future policymakers through a service-learning pedagogy. The goal of this research is to make it possible to efficiently treat shale oil and gas produced water at the industrial level. Toward this goal, the project will investigate a novel high throughput forward osmosis membrane design that is optimized for treating high-salinity produced water. The forward osmosis membrane will consist of an intermediate nanofibrous support layer and double ultrathin skins on both sides of the support layer. The support layer will be a porous nanofiber textile containing polyetherimide and graphene oxide. To reduce membrane fouling and to repel ammonia loss from the feeding produced water side, the membrane skins will be coated with zwitterionic polymers, which are highly hydrophilic. Membrane synthesis, characterization, and performance evaluation is integrated with molecular dynamics simulation to fabricate and optimize a membrane for produced water treatment using the forward osmosis process. The performance and stability of the developed membrane for treating produced water will be examined over the long-term, and the environmental and economic impacts of the new produced water treatment process will be evaluated through a life cycle assessment. 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.