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Carbon dioxide (CO2) management is critical for all life forms and certainly for all human space-flight missions. CO2 must be extracted and removed or recycled safely, reliably, and rapidly while maintaining CO2 levels within allowable limits independent of crew activity. In view of ESM considerations the system should minimize mass, volume, energy and crew maintenance. Such considerations favor regenerable systems. Our efforts in this direction are focused on a contained liquid membrane design enzyme catalyzed by carbonic anhydrase that exhibits high permeance, ca. 5*10−7 molesCO2/m2 s Pa, very high selectivity vs. nitrogen and is non-responsive to a wide variety of VOCs. Over the last year we have addressed five issues: scale-up, integrated water management, enzyme immobilization, system modeling, and process engineering design. We have developed a membrane element (10 cm × 10 cm × 0.67 cm) capable of removing 0.09 kg/d CO2 from a 0.5% feed stream.

The technologies for processing respiratory gases to support humans and plants and to provide material for regeneration of oxygen in Advanced Life Support applications remain far from optimal. Here we report on our ongoing efforts to develop an enzyme-based, hybrid, facilitated transport bioreactor for the efficient capture of CO2 from dilute respiratory gas streams. In this paper, we examine four different cases with respect to maintaining a driving force for removal of CO2 from respiratory gas.