Design and Preliminary Evaluation of a Novel Gravity Independent Rotating Biological Membrane Reactor

The integration of membrane-aeration technology with biological water processors has direct application to wastewater treatment in microgravity because of the ability to diffuse gases across the membrane without two-phase interactions (gas-liquid). Membrane-aeration bioreactors have demonstrated the ability to deliver a terminal electron acceptor (O₂) and substrates (CH₄ and H₂) to biofilms attached to the membrane surface. However, the process performance of these systems has been limited by mass transfer constraints. A novel bubbleless membrane-aeration bioreactor was design and tested at Kennedy Space Center. The Aerobic Rotational Membrane System (ARMS) consists of a rotational membrane module inside of a pressurized reactor vessel. Rotation of the membrane module enables a reduction in the mass transfer resistance coefficients associated with both the membrane/liquid boundary layer (k_La) and constituents in the bulk liquid, and it equalizes the concentration gradient across the bioreactor allowing for uniform biofilm formation and decreased bulk liquid O₂ transfer. Preliminary engineering tests have been conducted to determine the effect of key operational parameters (i.e. rotational speed, superficial velocity) on O₂ flux rates and hydrodynamic characteristics within the ARMS. This paper presents the ARMS design and results of the preliminary engineering tests.