Anaerobic digestion of space mission wastes

Abstract

The technical feasibility of applying leachbed high-solids anaerobic digestion for reduction and stabilization of the organic fraction of solid wastes generated during space missions was investigated. This process has the advantages of not requiring oxygen or high temperature and pressure while producing methane, carbon dioxide, nutrients, and compost as valuable products. Anaerobic biochemical methane potential assays run on several waste feedstocks expected during space missions resulted in ultimate methane yields ranging from 0.23 to 0.30 L g-1 VS added. Modifications for operation of a leachbed anaerobic digestion process in space environments were incorporated into a new design, which included; (1) flooded operation to force leachate through densified feedstock beds; and (2) separation of biogas from leachate in a gas collection reservoir. This mode of operation resulted in stable performance with 85% conversion of a typical space solid waste blend, and a methane yield of 0.3 Lg per g VS added after a retention time of 15 days. These results were reproduced in a full-scale prototype system. A detailed analysis of this process was conducted to design the system sized for a space mission with a six-person crew. Anaerobic digestion compared favorably with other technologies for solid waste stabilization.

Microbial community composition and dynamics in a semi-industrial-scale facility operating under the MixAlco™ bioconversion platform

“…Members of the class Clostridia were found in greatest abundance as fermentor acid concentrations increased, and they declined in parallel with fermentor productivity. The class Clostridia contains several known cellulose degraders and, not surprisingly, Clostridium ‐like organisms are frequently associated with mammalian gut microbial communities and the decomposition of crop residues, municipal solid waste, and other lignocellulosic materials (Chynoweth and Pullammanappallil 1996; Akasaka et al. 2003; Burrell et al.…”

Dialing Back the Doomsday Clock with Circular Bioeconomy

“…With no infinite mass fraction launch system, onboard and in-situ food production become vital for successful long-time deep space missions, and extraterrestrial body habitations. To achieve this, space farming would need to benefit from circular bioeconomy technologies and concepts such as AD [131][132][133]; IRA [116,134]; circularity [77][78][79][80][81][82]135]; bioregenerative life support system (BLSS) [136,137]; controlled ecological life support system (CELSS) [138][139][140]; and note by note cuisine (NNC) [141,142]. For greater plant utility and optimization, molecular pharming [143,144] could be applied as well.…”