Title: Biodegradation of petroleum hydrocarbon vapors: laboratory studies on rates and kinetics in unsaturated alluvial sand 
Resource Type: document --> technical publication --> journal article 
Country: EU Projects 
Year: 2003 
Availability: J. Contam. Hydrol. 66, no1-2, pp. 93-115 . (GRACOS Publication P25) 
Author 1/Producer: Höhener, P. 
Other Authors/Producers: Duwig, C., Pasteris, G., Kaufmann, K., Dakhel, N. and Harms, H. 
Author / Producer Type: EC Project 
Article Weblink (=direct link): http://cat.inist.fr/?aModele=afficheN&cpsidt=15167354  
EUGRIS Keyword(s): Contaminated land-->Contaminants-->MTBE
Contaminated land-->Soil and groundwater processes-->Microbiology
Short description: Extract: 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 piace before steady-state diffusive vapor transport through the horizontal column was achieved. Monod kinetic parameters K[s] and í[max] 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. 
Submitted By: Martin Bittens WhoDoesWhat?      Last update: 03/01/2007