Anaerobic Intrinsic Bioremediation of Whole Gasoline

EPA Grant Number: R827015-01-0
Title: Anaerobic Intrinsic Bioremediation of Whole Gasoline
Investigators: Joseph Suflita
Institution: University of Oklahoma
EPA Project Officer: Bala Krishnan
Project Period: February 1, 1999 to January 31, 2000 (N/C Ext. to February 28, 2001)
Project Amount: $130,036
Research Category: Intrinsic bioremediation/natural attenuation

Description:

The major accomplishments of this quarter were:

1. Continued monitoring of the terminal electron-accepting process in laboratory incubations examining whole gasoline
2. Demonstration of limited branched-alkane biodegradation in laboratory studies
3. Successful subculture of the n-alkane biodegradative activities under sulfate-reducing and methanogenic conditions.

   The incubation of the primary experiment of this research, the examination of the susceptibility of whole gasoline to anaerobic decay, ha been extended in order to allow for the fullest extent of biodegradation. Presently, samples that have been sacrificed and preserved over the last year are being analyzed for hydrocarbon depletion.

   In separate laboratory experiments, we have examined the fate of individual components of the gasoline mixture as sole substrates. These experiments have largely confirmed the results from the biodegradation of the gasoline mixture. In secondary enrichments, we have shown stimulation of both methanogenesis and sulfate reduction with n-alkanes as sole substrates. In a separate study, we have examined the fate of a series of methylpentanes as model branched alkanes. Again, the results have confirmed the pattern of biodegradation seen in the whole gasoline experiment. We found some biodegradation of the less substituted pentanes, most notably 3-methylpentane under sulfate-reducing conditions and to a lesser degree 2-methylpentane. We also observed a notable lack of biodegradation of both the dimethylated pentanes tested, 2,2-dimethylpentane, and 2,4-dimethylpentane.