PI: Arup SenGupta

Co-PI(s): Carlos Romero

University: Lehigh University

Increased population and gradual decrease in fresh water supply are propelling societies globally to rethink strategies to sustain potable and industrial water supply to meet the current and future demands. Climate variability has aggravated the crisis further by adversely impacting the reliability of existing fresh water resources. Many water treatment processes, reverse osmosis (RO) included, produce highly saline brine streams, and their in-land disposal poses insurmountable problems. In Pennsylvania, disposal of produced wastewater from Marcellus Gas Shale with total dissolved solids (TDS) greater than 150,000 mg/L is a huge environmental challenge, and deep well injection, although unsafe, is the only option at the present time. Currently, membrane distillation and vacuum distillation are the two processes commonly practiced prior to crystallization. However, scaling and fouling by calcium salts are not resolved. The proposed hybrid two-step desalination process with approximately 60-80 percent recovery takes advantage of a synergy between the unique swelling and shrinking property of high capacity of polymeric ion exchangers and the availability of any inexpensive source of heat, be it waste flue gas or inexpensive solar thermal energy, to further concentrate the brine and recover water. A spherical polymeric ion exchanger bead may be viewed as a cross-linked network of highly concentrated polyelectrolyte gel (≥6 Molar) that behaves like inter-connected elastic springs

capable of expanding or contracting with the uptake or release of water. The team will use commercial ion exchange resins from a PA Company (Purolite Inc.) and carry out laboratory tests using synthetic wastewater and marcellus produced wastewater with TDS greater than 100,000 mg/L. The primary goal of the project is to demonstrate that this novel humidification-dehumidification process aided by ion exchange resins can concentrate brine to over 300,000 mg/L without needing any external chemical addition, and the potential fouling by calcium salts is completely ruled out.