In February 2004 NASA released “The Vision for Space Exploration.” The goals outlined in this document include extending the human presence in the solar system, culminating in the exploration of Mars. A key requirement for this effort is to identify a safe and effective method to process waste. Methods currently under consideration include incineration, microbial oxidation, pyrolysis, drying, and compaction. Although each has advantages, no single method has yet been developed that is safe, recovers valuable resources including oxygen and water, and has low energy and space requirements. Thus, the objective of this work was to develop a low temperature oxidation process to convert waste cleanly and rapidly to carbon dioxide and water.
TDA and NASA Ames Research Center have developed a pilot scale low temperature ozone oxidation system to convert organic waste to CO2 and H2O. The system not only extracts water from the waste, but it also recovers the water produced from the ozone oxidation of the solid waste that can be utilized by the crew. During treatment the system also disinfects any residue remaining in the reactor. Experiments were conducted with solid wastes to demonstrate the process at large scale, quantify system level performance and identify the parameters that will optimize system design to full scale. The waste loading scales with the reactor size and the oxidation rate primarily scales with the ozone flow and its utilization through the reactor. At present, the average waste oxidation rate of a fecal simulant is 10.5 g/h, which can be increased to 36 g/h by replacing the ozone generator with a higher output unit. These data, along with current waste generation rate models, indicate that all of the waste from a single crew member in one day can be processed in a vessel that is 9.5 liters (2.5 gallons) for long term missions.