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The baseline hygiene water reclamation system for Space Station Freedom has been changed from Reverse Osmosis with Multifiltration post-treatment to stand-alone Multifiltration. The Multifiltration concept offers increased system reliability, a decrease in power consumption, and essentially 100% water recovery. Multifiltration is based on well documented sorption technology for removal of contaminant species. System complexity is minimal. Moving parts are limited to one pump and simple valving. Reliable microbial control is obtained by heat sterilization and by the use of iodine as a bactericide. Iodine addition is accomplished in the Unibeds with an iodinated resin which is also used in the Microbial Check Valve (MCV). Microbial Check Valves have proven reliable and effective on board the Space Shuttle since the beginning of the Shuttle program. Power consumption is primarily attributed to heat sterilization. The energy required for the pump and controls is relatively low.

Waste water pretreatment and recovered water posttreatment techniques are essential for Space Station life support in order to achieve the necessary quality required of recycled water. This paper identifies methods of pre- and post-treatment applicable to spacecraft water recovery by distillation. The results of laboratory investigations show that oxidizers, which typically have been components of urine pretreatment formulas, produce many volatile organic compounds that contaminate the distillate and must later be removed by posttreatment. Two new nonoxidizing urine pretreatment formulas have been tested which minimize the generation of volatile organics and thereby significantly reduce posttreatment requirements. Three posttreatment methods were identified from among the many candidates that look promising (either alone or in combination) for removing organic contaminants in recovered water to nondetectable or barely detectable levels.

The 60-Day and 90-Day closed manned chamber tests conducted by the McDonnell Douglas Corporation in the 1960s have been thoroughly reported in the literature. These tests evaluated, among other things, the leading water recycling systems developed at that time. During both tests, crew members ingested water reclaimed from urine and humidity condensate and performed personal hygiene tasks with water recycled in a separate loop. Since then, to this date (1995), no comparable testing has been carried out in the United States. Now, however, plans are being made to test modern water recycling systems in chamber tests with humans. This paper summarizes the earlier testing and highlights the lessons that were learned.