Effect of environmental conditions and microbial communities on ETBE biodegradation potential in groundwater

Report no. 19/20: This report describes research carried out to determine: a) the environmental conditions which may support Ethyl tert butyl ether (ETBE) biodegradation in groundwater, b) the prevalence of ETBE biodegradation potential at ETBE-release sites (mainly) within Europe, and c) the organisms and mechanisms involved in aerobic ETBE biodegradation. The research included laboratory biodegradation (microcosm) studies, using samples from an ETBE-impacted site in France, and complementary microbiological studies of groundwater samples collected from several ETBE-impacted sites. The results of this research suggest that biodegradation of ETBE is likely to occur in groundwater in the presence of dissolved oxygen and is not inhibited by the presence of other ether oxygenates, such as MTBE.

Hydrochemical assessments, based on the analysis of dissolved ETBE, TBA and dissolved oxygen, can be used to demonstrate ETBE biodegradation in groundwater at an ETBE-release site. An additional line of evidence that may be relevant at some sites is microbiological assessment of ETBE biodegradation potential. This is site-specific and may be appropriate in cases where the hydrochemical assessment suggests that conditions are favourable for ETBE biodegradation but this is not observed. In this case, the presence of the ethB gene in the aquifer microbial community should be determined using aquifer material (e.g. core samples) or mixed groundwater-aquifer material (e.g. sampled from monitoring wells).