Collaborative Research: Elucidating the Coupling of Inorganic Scaling and Organic Fouling in Reverse Osmosis Desalination: An Integrated Experimental and Computational Approach

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Climate change and anthropogenic pollution are contributing to the increasing scarcity of freshwater resources in many regions around the globe. In the United States, water stress in arid and semi-arid regions poses a threat to food production, energy generation, and ecological and human health. Desalination technologies can harvest purified water from seawater, saline groundwater, and wastewater and are an important tool to combat water scarcity. Reverse osmosis (RO) is a commercial desalination technology that relies on the permeation of freshwater through a dense membrane under an applied pressure. Despite its widespread application, the RO process is vulnerable to performance decay caused by fouling, or the unwanted deposition of substances on the membrane surface. This research aims to understand the interplay between two common types of RO fouling: organic fouling caused by the adsorption of organic matter and inorganic scaling caused by the precipitation of minerals. The investigators will integrate experimental measurements with computational simulations to reveal how organic foulants and inorganic scale-forming substances interact with each other during RO desalination. The investigators will lead research-related public engagement and outreach activities at both George Washington University and Colorado State University. Water sustainability-themed workshops will be hosted for students from local communities in Washington, D.C., and Colorado. Reverse osmosis (RO) is currently the state-of-the-art desalination technology due to its exceptional energy efficiency. Although the existence of inorganic scalants and organic foulants is known to greatly constrain the performance of RO, the combined effects of inorganic scaling and organic fouling are not well understood. The overarching goal of this research project is to elucidate the interactions of inorganic scalants with organic foulants at the membrane-water interface. The investigators will study the performance of thin-film composite polyamide membranes under combined inorganic scaling and organic fouling in RO and unravel the mechanisms by which organic foulants impact mineral scaling. Advanced modeling approaches will be employed to simulate nucleation kinetics of mineral scales in the presence of organic foulants, elucidating the role of organic foulants in controlling mineral nucleation at the molecular level. The performance of anti-fouling membranes under combined scaling and fouling will also be examined to inform membrane design. The project will close a fundamental knowledge gap by (i) elucidating the effects of combined scaling and fouling on RO membrane performance, which cannot be predicted by existing knowledge of individual scaling or fouling, (ii) advancing mechanistic understanding of how organic foulants regulate mineral nucleation and growth at engineered membrane surfaces, and (iii) demonstrating how functional membrane surfaces that are intended to mitigate organic fouling will respond to combined scaling and fouling. Educational and outreach aspects of the project will incorporate research findings into undergraduate and graduate course materials, introduce water sustainability-themed workshops in local communities, and promote the participation of underrepresented students in research.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.