Abstract
The feasibility and performance of full-scale applications of ERD in clay tills were investigated in a research project including
2 sites in Denmark, which have been undergoing remediation since 2006. At both sites organic substrates and bioaugmentation cultures
have been injected in TCE-contaminated clay till. An integrated investigative approach consisting of water and clay core sample analysis,
including stable isotopes and specific degraders, as well as analysis for chlorinated solvents, degradation products, donor fermentation
products and redox-sensitive parameters combined with modelling has been applied. The results showed that the chlorinated solvent TCE
was converted into its daughter products (cDCE, VC and ethene) but complete conversion of contaminants to ethene (as expected) was not
achieved within a timeframe of 4 years. Large variation in the effect of ERD in the clay matrix between sites, boreholes and even between
cores was observed. Four years post ERD initiation, the mass removal at the 2 sites varied between <5% and 50% within the treated zones.
Low mass removal was associated with degradation being restricted to narrow bioactive zones (few cm) around high permeability features
in some parts of the clay tills. The bioactive zones may expand in zones where both donor and chlorinated compounds are present. In some
cores TCE was depleted (degraded to DCE) in zones up to 1.8 m thick – an extent which could not be explained by diffusive loss to narrow
bioactive zones. Hence, biomass migration in the clay matrix appears to play an important role in terms of contaminant mass reduction.
2 sites in Denmark, which have been undergoing remediation since 2006. At both sites organic substrates and bioaugmentation cultures
have been injected in TCE-contaminated clay till. An integrated investigative approach consisting of water and clay core sample analysis,
including stable isotopes and specific degraders, as well as analysis for chlorinated solvents, degradation products, donor fermentation
products and redox-sensitive parameters combined with modelling has been applied. The results showed that the chlorinated solvent TCE
was converted into its daughter products (cDCE, VC and ethene) but complete conversion of contaminants to ethene (as expected) was not
achieved within a timeframe of 4 years. Large variation in the effect of ERD in the clay matrix between sites, boreholes and even between
cores was observed. Four years post ERD initiation, the mass removal at the 2 sites varied between <5% and 50% within the treated zones.
Low mass removal was associated with degradation being restricted to narrow bioactive zones (few cm) around high permeability features
in some parts of the clay tills. The bioactive zones may expand in zones where both donor and chlorinated compounds are present. In some
cores TCE was depleted (degraded to DCE) in zones up to 1.8 m thick – an extent which could not be explained by diffusive loss to narrow
bioactive zones. Hence, biomass migration in the clay matrix appears to play an important role in terms of contaminant mass reduction.
| Original language | English |
|---|---|
| Publication date | 2012 |
| Number of pages | 4 |
| Publication status | Published - 2012 |
| Event | 8th International Conference on Remediation of Chlorinated and Recalcitrant Compounds - Monterey Conference Center, Monterey, CA, United States Duration: 20 May 2012 → 24 May 2012 Conference number: 8 http://www.battelle.org/chlorcon |
Conference
| Conference | 8th International Conference on Remediation of Chlorinated and Recalcitrant Compounds |
|---|---|
| Number | 8 |
| Location | Monterey Conference Center |
| Country/Territory | United States |
| City | Monterey, CA |
| Period | 20/05/2012 → 24/05/2012 |
| Internet address |