Related theme: Sustainable remediation
Client: IRIS Industry Solutions
TAUW contact person:
The contamination was located on an industrial site fairly close to the workshop and on a busy private company road. To remediate the groundwater contamination, a field test was initially conducted in which a solution of oxygen-releasing components was injected into the groundwater. After that injection, oxygen is released which stimulates the natural degradation of the aromatic contamination in the aquifer. However, the results of this field test were disappointing because of the specific mineralogical composition of the soil, which prevented the oxygen reaching the bacteria that bring about the final degradation of aromatics.
TAUW opted for a resolutely different remediation approach based on compressed air injection and soil vapour extraction. Compressed air is injected into the soil and transfers groundwater contamination from the water phase to the gas phase. The injected compressed air laden with contamination is then captured by a soil vapour extraction system where the soil air is purified on an air activated carbon filter.
The aromatics volatise exponentially so that the contaminants can be removed rapidly (air sparging). Once the highest contaminant concentrations have been removed from the groundwater, compressed air is injected at a lower flow rate (bio sparging), allowing the introduced oxygen to slowly diffuse into the aquifer and become available to the bacteria.
Oxygen transfer via bio sparging is more efficient than with direct injection of oxygen-releasing components from the field test.
The air sparging/bio sparging remediation method enabled the work to be completed very quickly - within a period of 5 months. The remediation was carried out in a budget-friendly and ecologically responsible manner with minimal energy cost, minimal waste production and minimal consumption of consumables (activated carbon).
TAUW Belgium was sympathetic to the client’s concerns over business continuity and therefore planned the most disruptive work, such as breaking up the paving and installing the system, during the Christmas holiday period to minimise the impact on the business operations.
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