Low Temperature Dehydration and Sterilization of Wet Wastes

Water recovery from wastes is an important feature of resource recovery in advanced life support systems. Stabilization and disinfection is also necessary for safe storage of bio-hazardous waste on extended human missions. From waste material, such as human feces, toilet paper, wet plant biomass, trash, packaging material and tissues, generated on a six-man mission it is possible to extract approximately 7 kg water per day. The proposed microgravity compatible technology will simultaneously recover water and sterilize wet wastes using no consumables. The technology utilizes carbon dioxide, which is extracted from the cabin air. The dehydration and sterilization are performed at low temperatures (31?C) and moderate pressures (74-200 bar). At such conditions carbon dioxide exists in a supercritical state and has been demonstrated as an effective sterilant. In contrast to alternative drying technologies, pre-processing of the waste materials is not required because of the superior mass transport properties of supercritical fluids. For the Phase 1 project the feasibility of simultaneous dehydration and sterilization will be investigated using supercritical carbon dioxide. The focus of the Phase II effort will be to build a breadboard system for delivery to NASA for testing and evaluation in the BioPlex.