Cascade Distillation Subsystem Development Testing

Recovery of potable water from wastewater is essential for the success of long-term manned missions to the moon and Mars. Honeywell International and the team consisting of Thermodistillation Company (Kyiv, Ukraine) and NASA Johnson Space Center (JSC) Crew and Thermal Systems Division are developing a wastewater processing subsystem that is based on centrifugal vacuum distillation. The Wastewater Processing Cascade Distillation Subsystem (CDS) utilizes an innovative and efficient multi-stage thermodynamic process to produce purified water. The rotary centrifugal design of the system also provides gas/liquid phase separation and liquid transport under microgravity conditions. A five-stage prototype of the subsystem was built, delivered and integrated into the NASA JSC Advanced Water Recovery Systems Development Facility for development testing. Key performance criteria identified for the subsystem design are the production of recovered water at a rate of 5 kg/hr maximum and specific power consumption less than approximately 290 W-hr/kg. The system, currently in test, is planned to be challenged with a variety of ersatz and human-generated waste streams representative of pretreated urine, early lunar outpost, and transit mission wastewater. This paper provides a description of the CDS technology, a summary of the current CDS test activities, and data on the system's performance to date. In addition, the current plan for continued maturation of the CDS technology is discussed.