Anaerobic biotransformation of fuel oxygenates under sulfate-reducing conditions

The anaerobic biotransformation of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and methyl tert-amyl ether (TAME) was evaluated under different anoxic electron-accepting conditions. Enrichments were established with a polluted estuarine sediment inoculum under conditions promoting denitrification, sulfate reduction, Fe(III) reduction, or methanogenesis. Complete loss of MTBE and TAME was observed under sulfate-reducing conditions, concomitant with the reduction of sulfate. A stoichiometric amount of tert-butyl alcohol and tert-amyl alcohol accumulated indicating that O-demethylation was the initial step in MTBE and TAME biodegradation under sulfate-reducing conditions. No transformation of MTBE or TAME was observed under the other electron-accepting conditions over 3 years. Under all conditions tested, there was no biotic loss of ETBE observed. MTBE and TAME were depleted upon refeeding the sulfate-reducing cultures. This study definitely demonstrates the anaerobic biodegradability of MTBE and TAME under sulfate-reducing conditions.