Biochemical Methane Potential of Wastes Generated During Long Term Lunar Mission

The National Aeronautical and Space Administration (NASA) is considering manned long term exploratory missions to moon in the near future. Waste treatment and removal for missions to moon will be a challenge due to the longer mission duration. The present studies highlights the importance of a technology called ‘Anaerobic Digestion’ which not only reduces the wastes on the Lunar surface, but may provide significant fuel out of it during a year of exploration. Anaerobic digestion is a biochemical process that converts organic matter to biogas (which is mixture of 50-70% methane and rest carbon dioxide) through the concerted action of a syntrophic group of microorganisms under anaerobic (oxygen free) condition. Biochemical methane potential is a measure of sample biodegradability and measures methane generation potential under anaerobic digestion conditions. This study aimed to evaluate biochemical methane potentials of the individual components in lunar waste stream at thermophilic conditions, to determine extent and rate of bioconversion. Human waste and food waste demonstrated highest methane potential of 0.856 and 0.481 l/g at STP and complete biodegradability. Paper, cotton and clothing also showed good methane potentials and biodegradability. Other components such as packaging materials, wipes, grey tapes etc did not degrade. Methane from anaerobic digestion of waste generated from a years mission of a 4-person crew could provide 23% of the fuel required for LOX/methane engines in lunar ascent vehicle.