4 | LEHIGH ALUMNI BULLETIN | FROM THE NEST A new approach developed by Arup SenGupta, P.C. Rossin Professor of Civil and Environmental Engineering, Emeritus, and visiting researcher Hao Chen represents a leap forward in cleaning up and even potentially unlocking valuable resources lurking in the byproduct of industrial processes known as “brine”— wastewater containing levels of salt many times higher than seawater and often contaminated with pollutants. The current methods of dealing with this byproduct often compound environmental damage inherent in industrial processes. Developing methods for concentrating brine to levels conducive to the collection of crystallized solids has been made a priority of the U.S. Department of the Interior and other global water agencies. Crystallized solids can more easily be disposed of, reused for industrial processes and even “mined” for precious metals including lithium. A New Solution SenGupta and Chen have developed a new process, evaporative ion exchange (EIX), to concentrate brine at room temperature using air humidity and ion exchange. It uses a polymeric ion exchange resin bead, a type of gel with a high concentration of charged functional groups, or atoms whose electrical charge binds with ions of opposite charge. When the bead comes into contact with water, the resin’s internal pressure causes it to absorb water quickly while rejecting salts and other compounds. When then exposed to dry air, the resin releases water into the air through evaporation at room temperature without the need for external heat input. “This cycle can be repeated, allowing the resin to continuously concentrate solutions at ambient temperature,” SenGupta said. The Experiment To test the process, researchers conducted experiments using both laboratory-created synthetic hypersaline brine and hypersaline water collected from gas well sites in the Pennsylvania and New Jersey Marcellus Shale region. In addition to salt, the Marcellus sample contained high concentrations of barium cations, strontium cations and calcium ions. The EIX beads were placed in a bed, which was then filled with brine until the resin reached saturation. The bed was drained of brine, and then resin was exposed to blown, unheated air for evaporation, and the total volume and the total dissolved solids (TDS) of the remaining brine were measured. This cycle was then repeated using the remaining brine. After four cycles carried out with the Marcellus sample, the concentrations of barium, sodium and chlorine were concentrated beyond the solubility limit, resulting in direct crystallization of barium chloride and sodium chloride salts. “The most remarkable finding of this study is the precipitation/crystallization of salts from the hypersaline water from a Marcellus gas well after four EIX cycles at ambient temperature,” SenGupta said. “According to the literature, no other brine concentration process attains incipient crystallization at ambient temperature.” The study was completed with grant funding from the U.S. Bureau of Reclamation, the Pennsylvania Infrastructure Technology Alliance and a Lehigh faculty innovation grant. Looking Ahead SenGupta said the process’s advantages make him optimistic about the potential for the process to be scaled up for widespread use. The next steps would be to run a pilot system and record its process parameters and energy advantages compared to other elevated temperature processes.—Dan Armstrong RESEARCH New Process May Offer a Solution to Fracking Wastewater The approach represents a leap forward in dealing with “brine,” a super-salty industrial byproduct. CRISTIAN MARTIN / ISTOCK
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