Microbial Degradation of Fuel Oxygenates under Aerobic Conditions

This research determined the rate and extent of aerobic degradation of fuel oxygenates ethyl tert butyl ether (ETBE), tert amyl methyl ether (TAME) and ethyl alcohol (ethanol). Biodegradation was measured using gas chromatography (GC), respirometry, and biochemical oxygen demand (BOD) tests. Additionally, the research determined the effects of toluene on degradation rates. This microcosm study used a microbial consortium obtained from a petroleum refinery wastewater treatment facility. Respirometry data were collected from chambers containing pure oxygenates, or oxygenate/toluene mixtures. Samples were withdrawn periodically for GC analysis. Aerobic conditions were maintained in the chambers at all times. Degradation of oxygenates was compared to degradation of toluene, assuming first order decay. Across all experiments TAME degraded at 8.65 % the rate of toluene, ETBE at 8.17% the rate of toluene and ethanol at 156.79 % the rate of toluene. GC and respirometry data were the most suitable methods for measuring degradation. BOD provided acceptable results for toluene and ethanol but not for the slower degrading oxygenates. Finally, the presence of toluene slowed the degradation of both ETBE and TAME. The original document contains color images.