Composting on Mars or the Moon: I. Comparative evaluation of process design alternatives

Area of Science:

• Bioregenerative Life Support Systems
• Waste Management and Resource Recovery
• Environmental Engineering

Background:

• Composting is a promising technology for treating solid wastes and recovering resources in bioregenerative Advanced Life Support (ALS).
• Composting offers advantages such as compactness, low mass, ambient operating conditions, reliability, flexibility, simplicity, and operational forgiveness.
• The physical, chemical, and biological factors governing composting are well understood.

Purpose of the Study:

• To comparatively evaluate five generic composting systems for their suitability in Advanced Life Support.
• To identify the most viable composting system designs for bioregenerative life support on alien worlds.

Main Methods:

• Evaluation of five distinct composting facility designs and control strategies.
• Analysis of system behavior and process performance characteristics for each generic system.
• Comparative assessment of passive aeration, passive aeration with mechanical agitation, and three forced aeration systems (O2 feedback, temperature feedback, integrated O2/temperature feedback).

Main Results:

• Each of the five evaluated systems exhibited unique behavioral patterns and process performance characteristics.
• Passive aeration and passive aeration with mechanical agitation were deemed less suitable for ALS.
• Forced aeration systems, particularly those with temperature feedback control and integrated O2/temperature feedback control, demonstrated higher viability.

Conclusions:

• Only forced aeration systems with temperature feedback control (System 4) and integrated O2 and temperature feedback control (System 5) are considered viable candidates for Advanced Life Support on alien worlds.
• Further research is needed to determine which of the two viable systems is better suited for space applications.