In some situations, the residual contamination in the plume can be broken down (degraded) in a biological manner after the core has been removed. Depending on the nature and seriousness of the residual contamination, the degradation is stimulated by injecting oxygen and/or a carbon source together with nutrients.
We stimulate both aerobic and anaerobic degradation processes. Biological techniques can be a suitable and affordable alternative, especially in plume areas or as a biological barrier.
We carry out the design and monitoring of the degradation processes ourselves. In some cases, only monitoring of the biological degradation process is sufficient as an approach. But often stimulation of the degradation process is needed. In those situations we use the following techniques for decontamination:
- Bioventing the unsaturated zone
- Air-sparging the saturated zone
- Shock load injections (one-off injections of nutrients)
- Continuous injections via extraction and infiltration of groundwater with nutrients
Depending on the location-specific situation, we select our nutrients, compressed air, oxygen-releasing salts or nutrients. Very frequently, we also inject a a slow-release, soy-based, electron donor developed by our R&D department. We call this product ‘ENNA’.
We can also combine ENNA with the injection of zero-valent iron nanoparticles. The contamination is then tackled using chemical reduction in parallel to biological degradation. This product is called FENNA.