A short abstract of the doctoral research

In future space missions to the Moon or Mars, current resupply and waste management strategies will not be feasible. To address this limitation, the MELiSSA (Micro-Ecological Life Support System Alternative) project aims to develop a bioregenerative, closed-loop life support system that converts the waste generated by the crew into food, potable water, and a breathable atmosphere. At present, closing the carbon cycle by oxidizing the carbon in the organic waste to CO2 remains one of the main challenges in the loop. Similarly, on Earth, growing environmental pressures resulting from increased resource extraction and waste accumulation highlight the urgency of transitioning toward a more circular bioeconomy.

Thermophilic mixed-culture fermentation and microbial electrolysis cells have emerged as promising technologies for recovering resources from organic waste streams. This thesis explored the influence of several operational parameters (pH, feeding regime, substrate concentration) on microbial community dynamics and process performance in thermophilic mixed-culture fermentation. The biodegradability of protein- and polysaccharide-based bioplastics via thermophilic mixed-culture fermentation was also assessed to identify new valorisation routes for these materials. Furthermore, this thesis investigated the capacity of a microbial electrolysis cell to oxidize complex fermentation effluents to CO2, providing insights into the effect of various operational parameters on microbial community composition and process performance. Together, the findings of this thesis contribute to optimizing microbial processes for efficient carbon recovery, supporting the development of sustainable resource management strategies for applications on both Earth and in space.