Microbial Requirements for Optimal Surfactant Degradation in a Denitrifying, Fixed-Bed Bioreactor

Ground studies at Kennedy Space Center were conducted to determine microbial requirements of the Immobilized Microbe Microgravity Water Processing System (IMMWPS), a denitrifying, fixed-bed reactor designed for Shuttle flight-testing. The reactor was operated with a simulated graywater “waste stream” containing the surfactant Igepon TC-42^TM as the sole carbon source. Experiments were conducted to determine the effect of hydraulic retention time (HRT) and feed nutrient composition on surfactant degradation. The source of inoculum as well as procedure for inoculating the reactor was also examined. A complete nutrient mix in the feed formulation was required for sustained Igepon degradation throughout the reactor runs at the short (1.4 days) and intermediate (1.9 days) hydraulic retention time (HRT), regardless of inoculum source.