The Effect of Microbial Growth on Feed Stability and Delivery in a Denitrifying Fixed Bed Reactor Designed for Space Flight to Recycle Graywater 2002-01-2354

Ground studies at Kennedy Space Center were done to define and optimize performance of the Immobilized Microbe Microgravity Water Processing System (IMMWPS), a denitrifying, fixed-bed reactor designed for Shuttle flight-testing. The purpose of the current studies was to evaluate additional flight protocol issues, including microbial backgrowth in the influent tubing and concomitant reduction of influent Igepon levels prior to bioreactor treatment, and the effects of bioreactor shutdown for loading and launch. Experiments were done to evaluate sterilization procedures and the effect of delivery tubing diameter on microbial backgrowth. Analytical methods employed included ion-pairing reversed phase chromatography coupled with suppressed conductivity detection for monitoring Igepon concentrations in the influent and effluent, and acridine orange direct count (AODC) technique for quantifying microbial growth in influent lines.