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| Titel |
Reactive transport modeling for Cs retention: from batch to field experiments |
| VerfasserIn |
K. De Pourcq, C. Ayora, J. Carrera, M. García-Gutiérrez, T. Missana, M. Mingarro |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250068952
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| Zusammenfassung |
| A Permeable Reactive Barrier has been designed to treat 137Cs polluted groundwater. In order
to check both reactivity and permeability, laboratory batch and column tests combined with
reactive transport modeling have been performed. The trapping mechanism is based
on the sorption of cesium mainly on illite-containing clays. Batch experiments
were conducted to obtain the partition coefficients (Kd) of different clay samples in
solutions with different potassium concentration. A clear correlation of Kd values with
potassium content was observed. The results were modeled with a cation-exchange
model.
The permeability of the reactive material is provided by the dispersion of the clay on a
matrix of wooden shavings. Constant head tests allowed obtaining permeability values.
Several column experiments with different flow rates were conducted to confirm the 137Cs
retention under different conditions. A blind 1D reactive transport model based on the
cation-exchange model was able to predict reasonably well the results of column
experiments.
The reactive transport model, validated with the column experiments, was used to
investigate the performance and duration of 1m thick barrier under different scenarios (flow,
clay proportion, 137Cs and K concentration). As expected, the sensitivity tests proved that the
retention capacity of dissolved 137Cs in groundwater depends linearly on the amount of clay
used in the filling material. As well, the operation time increases linearly when decreasing the
flow rate. Finally, the concentration of potassium in inflow water has a remarkable and
non-linear influence in the retention of 137Cs. Very high concentrations of potassium are the
greatest threat and can lead to the unfeasibility of a permeable reactive barrier. Due to the
Cs-K competition, the barrier is comparatively more efficient to treat high concentrations of
137Cs.
Up to now, preliminary results from a field scale experiment have confirmed the reactivity
and permeability obtained from the laboratory tests and predicted by the reactive transport
modeling. |
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