Distillation Brine Purification for Resource Recovery Applications

Wastewater processing systems for space generate residual brine that contains water and salts that could be recovered to reduce life support consumables. The project assessed the use of ion-exchange resins to selectively remove salts from wastewater treatment brines. The resins were then regenerated for additional use. The intention would be to generate a Na/K and Cl rich or purified brine that would then be processed into high value chemicals, such as acids, bases, and/or bleach.

Water comprises the majority of the daily mass requirements for crewed space missions. Used for drinking, food prep, or hygiene, water is one of the most critical life support elements. Reliable water recovery is paramount for long term space exploration either on the International Space Station (ISS) or beyond Earth's gravity well. Advances in water recovery have allowed longer mission durations and decreased launch costs. In order to visit or even habituate extraterrestrial bodies (Mars, Europa) further advances in water recovery are needed. Current environmental control and life support systems on the ISS are focused on air and water recovery. Wastewater is pretreated with chromic acid and then distilled. The pretreatment turns about 10% to 30% of the wastewater into unusable brine and makes further water recovery difficult. In addition, no chemicals are retrieved for reuse from the brine. If the wastewater were treated in bioreactors and then distilled or filtered, chemical pretreatment would not be needed and the remaining brine could serve as a resource for chemical and further water recovery. Development and application of brine tolerant ion-exchange resins could provide more efficient methods for retrieving elements and pure water from salt water, and provide feed stocks for commercial processes that generate bleach, HCl, and Na/KOH (e.g., Chlor-alkalai Process). If proven feasible, the combined benefits would reduce consumables and further close the water loop for future space exploration. and generate consumable chemicals, such as HCl, NaOH , KOH and sodium hypochlorite (bleach).