Application of a First Generation Biotrickling Filter Model for Design of BREATHe I Experiments--EAC Presentation 2004
Document Type Presentation
Poster presentation focusing on Bio-Regenerative Environmental Treatment for Health (BREATHe) I. Part of Project 6 - Bio-Regenerative Environmental Treatment for Health (BREATHe) BREATHe. One presentation in "EAC Presentation 2004" entry.
A first generation model has been developed to predict process performance and identify important design parameters for the operation of the Bioregenerative Air Treatment for Health I (BREATHe I). BREATHe I is a biotrickling filter intended for advanced life support and has been designed to simultaneously treat graywater and waste gas from a solids treatment system, high in ammonia (NH3), hydrogen sulfide (H2S), and carbon dioxide (CO2). Surfactant removal was tracked in the liquid phase and hydrogen sulfide and ammonia removal were tracked in the gas phase. Because significant controversy exists regarding operation of biotrickling filters with cocurrent versus countercurrent flow, the expected performance for removal of hydrogen sulfide and ammonia was evaluated for both flow schemes using the model. Results indicated that under BREATHe I operating conditions, a countercurrent flow scheme would result in significant contamination of water immediately before the outlet, resulting in unacceptable performance for liquid contaminant removal. Future experiments will focus only on cocurrent operation. A sensitivity analysis was performed and the most sensitive parameters were surface area and liquid velocity. Experiments have been designed that address optimization in terms of these important design parameters. The model was also used to track expected oxygen consumption and carbon dioxide production through the BREATHe I system. Because the composition of waste gas to be treated by BREATHe I is not well characterized, reactor performance was predicted for various contaminant loading rates. High increases in ammonia gas input may result in undesirable levels of ammonia in liquid and gas outputs whereas increases in surfactant and hydrogen sulfide do not appear to result in unacceptable effluent quality. Many model input parameters were estimated because the values are not available in the literature. Of special importance are surfactant biodegradation parameters. Model results showed that changes in the maximum specific growth rate (q) and half saturation constant (Ks) resulted in very different surfactant removal efficiencies. Experiments are underway to determine realistic estimates for these parameters.
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