Project objectives:
Effective biological remediation of MTBE could be a low cost alterative of the conventional techniques. But the implementation of biodegradation processes
in natural environments such as contaminated aquifers seems to be rather difficult.
IThe joined research project METLEN (Methyl Tert-Butyl Ether – Leuna as a reference test site for the implementation of the Enhanced Natural Attenuation)
has been formed to compare and verify the properties of different technologies for the enhancement of the natural biodegradation at a real contaminated site.
It integrates a consortium of different research groups from Germany (UFZ Leipzig-Halle, Univ. Tübingen, Univ. Kiel, Univ. Dresden), Denmark (DTU) and Canada
(Univ. Waterloo).
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Project
Summary:
In preliminary laboratory experiments by our and other groups three different strategies have been demonstrated to be successful in degrading MTBE. These
strategies are:
1. Aerobic degradation using either autochthonic bacteria or a consortium of specialized bacteria at optimized conditions.
2. Cometabolic degradation (the first reaction step is catalyzed by monooxigenases, which have to be induced by other compounds such as methane, propane
or pentane).
3. Anoxic degradation using alternative electron acceptors.
It is the aim of this project, to determine the optimal conditions for an enhanced natural attenuation of MTBE in the aquifer. For that purpose, a conditioning
unit containing 5 separated channels (2 m high and 10 m long) has been placed into the aquifer.
The naturally occurring processes within the aquifer will be supported and enhanced through the addition of, e.g., electron acceptors, catalysts and microorganisms.
For the addition of the supporting substances, the conditioning unit is used. The pilot-scale conditioning unit allows a controlled flow of contaminated
groundwater. It also acts as a reaction tool for chemical and microbial processes. After passing the conditioning unit, the groundwater is reinfiltrated
into the downstream aquifer. The aquifer itself is used as a reaction area.
In the proposed project, MTBE as a recalcitrant compound is taken as a model substance. The solutions to be developed can be transferred to other sites, where
the ENA approach is applicable.
The microbial subprojects are conceived in two different phases. During the preliminary lab-scale phase microbiological tests will be carried out, in
order to simulate the fundamental degradation conditions. In the following pilot-scale study, the results will be transferred to the field, tested and optimised.
This second phase is accompanied by further lab-scale investigations. One subproject investigates the chemical degradation of MTBE. Since there is only
a small amount of data available on the environmental impact of MTBE within Germany, samples will be collected from surface and groundwater sources in order
to investigate the possible MTBE impact. In addition, models will be developed on MTBE transport in and between the different environmental compartments
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Dr Stefan Gödeke