Design of Anaerobic Digestion Systems for Closed Loop Space Biomanufacturing



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2020 International Conference on Environmental Systems


Space biomanufacturing has the potential to substantially reduce the launch mass of long-duration manned missions. Active research areas include enhancing methane conversion to polyhydroxybutyrate by methanotrophs to enable 3D-printed mission tools. Because anaerobically digesting mission wastes can recycle essential carbon, this process can provide necessary biomanufacturing feedstocks like methane. Thus, this paper analyzes the costs and benefits of adding anaerobic digestion to aid space biomanufacturing. First, stoichiometry determines theoretical yield from inedible food biomass (e.g., the straw and husk of rice) and human waste. Thereafter, this work examines how digester design and operating conditions, including operating temperature, solid loading density, digestion duration, and pretreatment impact methane yield. This paper also studies numerous combinations of possible wastes. The work assesses impact through a systems engineering analysis that optimizes performance and specifications of this two-step process via the Equivalent System Mass (ESM) metric. ESM augments traditional shipped mass costs with those of pressurized volume, demanded power and thermal control, and needed crew time. This analysis helps quantify the extent of loop closure for space biomanufacturing and its trade-off with ESM, and finds that it is possible to close as much as one third of the loop. This paper also incorporates a parametric sensitivity analysis to highlight the positive impact that mission horizon increase has on anaerobic digestion viability.


Alexander Benvenuti, University of Florida, US
Saige Drecksler, University of Florida, US
Soumyajit Sen Gupta, University of Florida, US
Amor Menezes, University of Florida, US
ICES308: Advanced Technologies for In-Situ Resource Utilization
The proceedings for the 2020 International Conference on Environmental Systems were published from July 31, 2020. The technical papers were not presented in person due to the inability to hold the event as scheduled in Lisbon, Portugal because of the COVID-19 global pandemic.


Space biomanufacturing, Anaerobic digestion, Design optimization