Anaerobic degradation of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA)

The potential for anaerobic degradation of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) was investigated in laboratory incubations of sediments from a petroleum-contaminated aquifer and in aquatic sediments. The addition of humic substances (HS) stimulated the anaerobic degradation of MTBE in aquifer sediments in which Fe(lll) was available as an electron acceptor. This is attributed to the fact that HS and other extracellular quinones can stimulate the activity of Fel(III)-reducing microorganisms by acting as an electron shuttle between Fe(lll)reducing microorganisms and insoluble Fe(lll) oxides. MTBE was not degraded in aquifer sediments without Fe(III) and HS. [C-14]-MTBE added to aquatic sediments adapted for anaerobic MTBE degradation was converted to (CO2)-C-14 in the presence or absence of HS or the HS analog, anthraquione-2,6-disulfonate, Unamended aquatic sediments produced (CH4)-C-14 as well as (CO2)-C-14 from [14C]-MTBE. The aquatic sediments also rapidly consumed TEA under anaerobic conditions and converted [C-14]-TBA to (CH4)-C-14 and (CO2)-C-14. An adaptation period of ca. 250-300 days was required prior to the most rapid anaerobic MTBE degradation in both sediment types, whereas TEA was metabolized in the aquatic sediments without a lag. These results demonstrate that, under the appropriate conditions, MTBE and TEA can be degraded in the absence of oxygen. This suggests that it may be possible to design strategies for the anaerobic remediation of MTBE in petroleum-contaminated subsurface environments.