ANAEROBIC BIODEGRADATION OF GASOLINE OXYGENATE - EXTRAPOLATION OF INFORMATION TO MULTIPLE SITES AND REDOX CONDITIONS

A series of alcohol, ketone, ester, and ether oxygenates were tested for their susceptibility to anaerobic decay in samples from four chronically contaminated sedimentary environments. The effect of various electron accepters on oxygenate biodegradation was also evaluated with a single inoculum source. In addition, two acetogenic bacteria were tested for their ability to metabolize selected oxygenate compounds. The susceptibility of the test oxygenates to anaerobic decay could be related to their chemical structure. That is, compounds other than the ethers that possessed primary or secondary substituted carbon atoms were readily degraded under all conditions tested while compounds that had tertiary substituted carbon atoms resisted biodegradation. The ether oxygenates were generally not degraded when incubated with various inocula, regardless of the electron acceptor status. The exceptions included methyl butyl ether, which was depleted in both sulfate-reducing and methanogenic incubations, and the partial transformation of methyl tert-butyl ether to tert-butanol after a 152-day acclimation period in a single replicate from a river sediment chronically contaminated with fuel. Heat-inactivated control incubations suggested that the latter transformation was biologically catalyzed. This study provides a basis for assessing the environmental fate characteristics of the frequently used gasoline oxygenates as well as several potential alternate fuel additives.