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Although bioprocessors have been successfully tested in ground test experiments as primary wastewater processors [1, 2 and 3], the transition required for operation of a bioprocessor in microgravity is complicated by the absence of gravity and buoyancy-driven convection. Gases are present in the wastewater bioprocessor from numerous sources including aeration, metabolic production and operation. This paper presents an innovative approach to the delivery of metabolically-required oxygen to a bioprocessor. A bioprocessor that provides oxygen delivery and bacterial support using membranes has been developed and tested during the past two years. Bench-top laboratory results have demonstrated that Total Organic Carbon (TOC) degradation above 95%, and nitrification above 80% can be maintained, while denitrification typically ranged between 5-25% in a membrane bioprocessor system (MBS).

Ground-based laboratory and closed-chamber human tests have demonstrated the ability of microbial-based biological processors to effectively remove carbon and nitrogen species from regenerable life support wastewater streams. Application of this technology to crewed spacecraft requires the development of gravity-independent bioprocessors due to a lack of buoyancy-driven convection and sedimentation in microgravity. This paper reports on the development and testing of membranebased biological reactors and addresses the processing of planetary and International Space Station (ISS) waste streams. The membranes provide phase separation between the wastewater and metabolically required oxygen, accommodate diffusion-driven oxygen transport, and provide surface area for microbial biofilm attachment. Testing of prototype membrane bioprocessors has been completed.