Design of a Post-Processor for a Water Recovery System

An advanced water recovery system requires the development of a minimum-consumable post-processor system to produce potable water that meets NASA requirements. Residual organic impurities and ammonium, nitrite, and nitrate ions are the principal challenges to the system. Ion exchange resins and organic removal materials that elute minimum organics were investigated. UP604 (Rohm & Haas) and NRW36/36SC (Purolite) ion exchange resins were shown to have comparable removal capacities of 1.29-1.78 meq/mL of bed volume. The organic removal materials exhibited poor removal capacities of less than 0.5 mg/mL of bed volume. Two ultraviolet photo-oxidative processes were investigated to reduce the need for expendable organic removal materials. A photolytic and a photocatalytic process both demonstrated the ability to reduce organic impurities to less than 500 μg/L. A description of these tests and results are discussed and presented in detail in this paper.