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A Two Stage Reverse Osmosis System in combination with a Membrane Vacuum Distillation Water Processor have been the focus of research for the water reclamation subsystem within the environmental control and life support system (ECLSS). Purification tests on waste water and urine have been conducted. Reverse osmosis (RO) and membrane distillation (MD) remove a high percentage of inorganic salts, but are ineffective for removal of some organic compounds such as alcohols and organic acids. The addition of a photodegradation subsystem with TiO2 photocatalysts to this water reclamation system has potential advantages of cost performance, energy savings, and the capability to remove alcohols and organic acids. In this research, the removal of alcohols and organic acids using TiO2 photocatalysts was investigated and basic data on efficiency of the photocatalysts were acquired.

The photocatalytic oxidation of trace contaminants such as human metabolite gas and outgas from the component materials over a UV-illuminated film of titanium dioxide (TiO2) has been studied to apply for an environmental purification in manned spacecraft. The trace contaminants studied were as follows: methanol, ethanol, acetal-dehyde, toluene, acetone, methane, ethylene, ammonia, 1,4-pentadiene, hydrogen sulfide, carbonyl sulfide, hydrogen and carbon monoxide. Most of these compounds are the representative human metabolic gas. It was found that these compounds except for methane, ethylene, carbonyl sulfide, hydrogen and carbon monoxide are sufficiently removed in the photocatalytic reactor. This report describes the result of the removal test using the photocatalysts performed in National Space Development Agency of Japan/Tsukuba Space Center (NASDA / TKSC).