The Impact of the Water Recovery & Management (WRM) Subsystem Wastewater Recovery Efficiency Upon the Space Station Freedom ECLSS Water Balance

A parametric study of the impact of the ECLSS Water Recovery Subsystem wastewater processing efficiency upon the overall Space Station Freedom water balance was performed. In this study, a representative range of recovery efficiencies was used for each of the three different water recovery processes. The types of processes corresponded to the baseline equipment considered for potable (Multifiltration), hygiene (Reverse Osmosis), and urine/flush (Thermoelectric Integrated Membrane Evaporation Subsystem) waste water recovery. Recovery efficiencies ranging from 80 percent to 99 percent were examined, corresponding to published efficiency values available in current technical literature. The recovery efficiency associated with the hygiene wastewater reclamation process proved to be particularly significant in determining the overall Space Station Freedom ECLSS water balance because of the relatively large volume of fluid treated within this loop. The analysis also indicated that a positive ECLSS water balance depended upon the ability to double process the concentrated brine discharged from the Reverse Osmosis waste-hygiene-water processor. Implications of the Water Recovery and Management (WRM) subsystem sensitivity analysis results upon the Space Station Freedom ECLSS, as well as the effects upon the propulsion and fluid management systems, are discussed.