2011-02-182005-08http://hdl.handle.net/2346/11751Texas Tech University (TTU) works in conjunction with NASA to develop a wastewater recovery system robust enough for use on long term-space missions. Biological treatment has been the primary focus at TTU, with specific thrusts in developing a biological treatment system that may be operated with minimal crew maintenance and low energy and mass requirements. Hollow fiber membrane bioreactors (HFMBRs) may be used for biological wastewater treatment, and may be integrated with NASA’s current research developments. The goal of this research is to (a) evaluate the effect of mass transfer by the use of microporous membranes and their application for microgravity conditions; (b) compare the effect of membrane type and configuration on treatment efficiency to previous literature values; and (c) determine the amount and distribution of biofilm growth within the reactor. Therefore, the objective of this research was accomplished using a microporous HFMBR. From the experimental studies performed for this thesis it was found that the HFMBR exhibits promising use in space applications. Maximum nitrification efficiency at low loading rates and high HRTs were accomplished using the HFMBR. Therefore, characteristics such as, suitable bioreactor size and the efficiency obtained during its operation, the HFMBR offer a potential for NASA’s needs; nonetheless, developing a system with more favorable system hydrodynamics would aid to improve treatment efficiency in a HFMBRapplication/pdfengMembrane aerated bioreactorsMass transferNitrificationThesisUnrestricted.