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J Contam Hydrol

Title:		Biodegradation of petroleum hydrocarbon vapors: laboratory studies on rates and kinetics in unsaturated alluvial sand
Author(s):		Hohener P; Duwig C; Pasteris G; Kaufmann K; Dakhel N; Harms H;
Address:		"Swiss Federal Institute of Technology (EPFL), ENAC-ISTE-LPE, CH-1015 Lausanne, Switzerland. patrick.hoehener@epfl.ch"
Journal Title:		J Contam Hydrol
Year:		2003
Volume:		66
Issue:		1-Feb
Page Number:		93 - 115
DOI:		10.1016/S0169-7722(03)00005-6
ISSN/ISBN:		0169-7722 (Print) 0169-7722 (Linking)
Abstract:		"Predictions of natural attenuation of volatile organic compounds (VOCs) in the unsaturated zone rely critically on information about microbial biodegradation kinetics. This study aims at determining kinetic rate laws for the aerobic biodegradation of a mixture of 12 volatile petroleum hydrocarbons and methyl tert-butyl ether (MTBE) in unsaturated alluvial sand. Laboratory column and batch experiments were performed at room temperature under aerobic conditions, and a reactive transport model for VOC vapors in soil gas coupled to Monod-type degradation kinetics was used for data interpretation. In the column experiment, an acclimatization of 23 days took place before steady-state diffusive vapor transport through the horizontal column was achieved. Monod kinetic parameters Ks and vmax could be derived from the concentration profiles of toluene, m-xylene, n-octane, and n-hexane, because substrate saturation was approached with these compounds under the experimental conditions. The removal of cyclic alkanes, isooctane, and 1,2,4-trimethylbenzene followed first-order kinetics over the whole concentration range applied. MTBE, n-pentane, and chlorofluorocarbons (CFCs) were not visibly degraded. Batch experiments suggested first-order disappearance rate laws for all VOCs except n-octane, which decreased following zero-order kinetics in live batch experiments. For many compounds including MTBE, disappearance rates in abiotic batch experiments were as high as in live batches indicating sorption. It was concluded that the column approach is preferable for determining biodegradation rate parameters to be used in risk assessment models"
Keywords:		"Biodegradation, Environmental Gases Humans *Hydrocarbons Models, Chemical *Petroleum *Silicon Dioxide *Soil Pollutants *Water Pollutants, Chemical;"
Notes:		"MedlineHohener, Patrick Duwig, Celine Pasteris, Gabriele Kaufmann, Karin Dakhel, Nathalie Harms, Hauke eng Research Support, Non-U.S. Gov't Netherlands 2003/10/01 J Contam Hydrol. 2003 Oct; 66(1-2):93-115. doi: 10.1016/S0169-7722(03)00005-6"