A rotating membrane contactor: Application to biologically active systems

Gas transfer through hollow fiber membranes allows for rapid transfer kinetics, high transfer efficiencies, and the ability to precisely control transfer rates. Despite these advantages, membrane gas transfer has not been used extensively in industrial fermentation or wastewater treatment. Module plugging and biofouling are problematic with current contactor designs, making membrane gas transfer unattractive for applications where the growth of microorganisms is encouraged. Recently, a novel rotating contactor configuration was designed to give high transfer rates and simultaneously alleviate these problems. In the rotating contactor configuration, the hollow fiber membranes are pulled through the water, reducing energy requirements. Solids are also able to pass through the fluidized fibers without being filtered. In addition, the entire fiber length experiences a similar flow velocity. This makes the control of biological fouling possible. Pilot plant experiments on a rotating membrane contactor operated in wastewater are presented. The performance of the rotating contactor design in such an environment where the potential for biological fouling exists is evaluated as a function of operating parameters and time in service. Membrane failures are addressed and the transfer performance is compared to other contactor configurations and aeration systems.