Aquifer studies, MTBE

Schirmer M, JF Barker (1998) A study of long-term MTBE attenuation in the Borden aquifer, Ontario, Canada. Ground Water Monitoring and Remediation. 113-122. 

A number of site studies evaluating different methods to clean up aquifers contaminated by MTBE, have been conducted, mainly in the United States (for a review, see [12]). The results demonstrated that bioremediation was a possible option in 57 of the 244 cases studied [ 19,20]. 

Obviously in cases where no biodegradation capacity was detected, the use of MNA would not be appropriate. On the contrary, the use of efficient and well-adapted strains could be suitable for cleaning-up the sites. Bioaugmentation was a valuable option in some cases of aquifers contaminated with MTBE [41,42]. The present study showed that microcosms that efficiently degraded MTBE and/or ETBE could be obtained following enrichment culture of material from contaminated sites, emphasizing the potential for bioaugmentation processes in contaminated sites. 

As shown in several studies, optimal performance of the ENA approach requires not only an optimal timing of the gas injection system but also an optimal arrangement of the injection wells in the aquifer. For this purpose, Salanitro et al. [15] as well as Smith et al. [44] used an array of injection wells arranged in two to four rows. The injection wells were installed at two different depths depending on the geological structure of the aquifer. In addition. Smith et al. [44] optimized the horizontal and vertical positions of the gas injection points according to the MTBE concentrations in the aquifer. 

When the biodegradation of MTBE was investigated in laboratory columns packed with aquifer sediments it was shown to degrade only in the absence of BTEX. In this study, it was concluded that MTBE would not degrade in the presence of significant concentrations of more readily degradable contaminants such as BTEX compounds [84]. 

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