Characterization of microbial and chemic

Solid-waste treatment in space for Advanced Life Support (ALS) applications requires that the material can be safely processed and stored in a confined environment. Many solid wastes are not stable because they are wet (40–90% moisture) and contain levels of soluble organic compounds that can contribute to the growth of undesirable microorganisms with concomitant production of noxious odors. In the absence of integrated ALS systems on orbit, permanent gas, trace volatile organic, and microbiological analyses were performed on crew refuse returned from the volume F “wet” trash of three consecutive Shuttle missions (STS-105, 109, and 110). These analyses were designed to characterize the short-term biological stability of the material and assess potential crew risks resulting from microbial decay processes during storage. Waste samples were collected post-orbiter landing and sorted into packaging material, food waste, toilet waste, and bulk liquid fractions deposited during flight. Aerobic and anaerobic microbial loads were determined in each fraction. Experiments were performed to determine the aerobic and anaerobic biostability of refuse stored for varying periods by monitoring CO2 and laboratory analysis for hydrogen sulfide and methane production. Volatile organic compounds and permanent gases were analyzed using EPA Method TO15.