title: Aerobic biodegradation of iso-butanol and ethanol and their relative effects on BTEX biodegradation in aquifer materials.
abstract: The aerobic biodegradability of iso-butanol, a new biofuel, and its impact on benzene, toluene, ethylbenzene and xylenes (BTEX) degradation was investigated in aerobic microcosms consisting of groundwater and sediment from a California site with a history of gasoline contamination. To the best of our knowledge this is the first study directly examining the effects of iso-butanol on BTEX degradation. Microcosms that received either low (68 μM) or high (3400 μM) concentrations of iso-butanol showed complete biodegradation of iso-butanol within 7 and 23 d, respectively, of incubation at 15°C under aerobic conditions. A maximum utilization rate coefficient of 2.3±0.1×10⁻⁷ μmol cell⁻¹ h⁻¹ and a half saturation constant of 610±54 μM were regressed from the iso-butanol data. Iso-butanol biodegradation resulted in transient formation of the degradation intermediate products iso-butylaldehyde and iso-butyric acid, and both compounds were subsequently degraded within the timeframe of the experiments. Ethanol was biodegraded more slowly than iso-butanol. Ethanol also exhibited greater adverse impacts on BTEX biodegradation than iso-butanol. Results of the study suggest that iso-butanol added to fuels will be readily biodegraded in the environment under aerobic conditions without the accumulation of major intermediate products (iso-butylaldehyde and iso-butyric acid), and that it will pose less impacts on BTEX biodegradation than ethanol.
authors.affiliation: Shaw Environmental Inc., Lawrenceville, NJ 08648, USA.
authors.forename: Charles E
authors.initials: CE
authors.lastname: Schaefer
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Yang
authors.forename: Oliver
authors.initials: O
authors.lastname: Pelz
authors.forename: David T
authors.initials: DT
authors.lastname: Tsao
authors.forename: Sheryl H
authors.initials: SH
authors.lastname: Streger
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Steffan
mesh_terms: D000332:Aerobiosis; D001420:Bacteria, Aerobic / Q000378:metabolism; D001554:Benzene / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D001555:Benzene Derivatives / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D001673:Biodegradation, Environmental; D000440:Butanols / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D000431:Ethanol / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D005618:Fresh Water / Q000737:chemistry; D019015:Geologic Sediments / Q000737:chemistry; D014050:Toluene / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D014992:Xylenes / Q000032:analysis / Q000737:chemistry / Q000378:metabolism
chemical_list: D001555:Benzene Derivatives; D000440:Butanols; D014874:Water Pollutants, Chemical; D014992:Xylenes; D014050:Toluene; D000431:Ethanol; C040507:isobutyl alcohol; D001554:Benzene; C004912:ethylbenzene