Search Results

Catalytic oxidation has proven to be an effective addition to the baseline multifiltration (MF) water reclamation technology which will be used on Space Station Freedom (SSF). Low molecular weight, polar organics such as alcohols, aldehydes, ketones, amides, and thiocarbamides which are poorly removed by the baseline MF technology can be oxidized to carbon dioxide at low temperature (121 C). The catalytic oxidation process by itself can reduce the Total Organic Carbon (TOC) to below 500 ppb for solutions designed to model these waste waters. Individual challenges by selected contaminants have shown only moderate selectivity towards particular organic species. The combined technology is applicable to more complex waste water generated in the Environmental Control and Life Support System (ECLSS) aboard SSF.

Life Sciences research on Space Station will utilize rats to study the effects of the microgravity environment on mammalian physiology and to develop countermeasures to those effects for the health and safety of the crew. The animals will produce metabolic water which must be reclaimed to minimize logistics support. The condensate from the Research Animal Holding Facility (RAHF) flown on Spacelab Life Sciences-2 (SLS-2) in October 1993 was used as an analog to determine the type and quantity of constituents which the Space Station (SS) water reclamation system will have to process. The most significant organics present in the condensate were 2-propanol, glycerol, ethylene glycol, 1,2-propanediol, acetic acid, acetone, total proteins, urea and caprolactam while the most significant inorganic was ammonia. Microbial isolates included Xanthomonas, Sphingobacterium, Pseudomonas, Penicillium, Aspergillus and Chrysosporium.

Development testing of the Space Station Freedom (SSF) Water Recovery and Management Subsystem is being conducted by the Marshall Space Flight Center Environmental Control and Life Support (ECLS) Branch and the Boeing Missiles and Space Division. The testing program is designed to define integrated subsystem performance, one aspect of which is assessing the quality of the waste and product waters. Recent efforts have focused on maximizing the characterization of water contaminants to more fully account for the total organic carbon and ionic conductivity of the various waste and product waters. Total organic carbon accountability improved with the application of new analytical methods for certain classes of water soluble compounds. Methods developed for the detection of aldehydes, glycols, and low-level total organic carbon are discussed.

Due to modifications to the ISS waste water composition, the concentration of volatile organic contaminants in the original baseline has significantly increased in the feed to the Water Processor Assembly (WPA). In parallel, the specified ISS oxygen supply pressure to the WPA increased, resulting in a higher flow rate of oxygen to the WPA catalytic oxidation reactor. Preliminary testing at Hamilton Sundstrand indicated that the higher oxygen flow rate would increase the WPA capacity for volatile organics. Following an analysis of the expected waste water composition, personnel at NASA MSFC and Hamilton Sundstrand conducted a test of a flight-like reactor to assess its capacity for the higher organic loads. The results of this test verify the WPA can accommodate the expected organic load in the ISS waste water with margin.

A series of tests has been conducted at the NASA Marshall Space Flight Center (MSFC) to evaluate the performance of the Space Station Freedom (SSF) water recovery system. Potable and urine reclamation processors were integrated with waste water generation equipment and successfully operated for a total of 144 days. This testing marked the first occasion in which the waste feed sources for previous potable and hygiene loops were combined into a single loop and processed to potable water quality. Reclaimed potable water from the combined waste waters routinely met the SSF water quality specifications. In the last stage of this testing, data was obtained that indicated that the Water Processor (WP) presterilizer may not be required to meet the potable water quality specification.