| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Fagerlund, Fritjof, et al.
(author)
-
PCE dissolution and simultaneous dechlorination by nanoscale zero-valent iron particles in a DNAPL source zone
- 2012
-
In: Journal of Contaminant Hydrology. - : Elsevier BV. - 0169-7722 .- 1873-6009. ; 131:1-4, s. 9-28
-
Journal article (peer-reviewed)abstract
- While the capability of nanoscale zero-valent iron (NZVI) to dechlorinate organic compounds in aqueous solutions has been demonstrated, the ability of NZVI to remove dense non-aqueous phase liquid (DNAPL) from source zones under flow-through conditions similar to a field scale application has not yet been thoroughly investigated. To gain insight on simultaneous DNAPL dissolution and NZVI-mediated dechlorination reactions after direct placement of NZVI into a DNAPL source zone, a combined experimental and modeling study was performed. First, a DNAPL tetrachloroethene (PCE) source zone with emplaced NZVI was built inside a small custom-made flow cell and the effluent PCE and dechlorination byproducts were monitored over time. Second, a model for rate-limited DNAPL dissolution and NZVI-mediated dechlorination of PCE to its three main reaction byproducts with a possibility for partitioning of these byproducts back into the DNAPL was formulated. The coupled processes occurring in I he flow cell were simulated and analyzed using a detailed three-dimensional numerical model. It was found that subsurface emplacement of NZVI did not markedly accelerate DNAPL dissolution or the DNAPL mass-depletion rate, when NZVI at a particle concentration of 10 g/L was directly emplaced in the DNAPL source zone. To react with NZVI the DNAPL PCE must first dissolve into the groundwater and the rate of dissolution controls the longevity of the DNAPL source. The modeling study further indicated that faster reacting particles would decrease aqueous contaminant concentrations but there is a limit to how much the mass removal rate can be increased by increasing the dechlorination reaction rate. To ensure reduction of aqueous contaminant concentrations, remediation of DNAPL contaminants with NZVI should include emplacement in a capture zone down-gradient of the DNAPL source.
|
|
| 5. |
|
|
| 6. |
- Yang, Zhibing, et al.
(author)
-
Macro-scale constitutive relationships for CO2 migration in heterogeneous geological formations
- 2012
-
Conference paper (other academic/artistic)abstract
- Numerical models have been developed and applied to migration of geological stored carbon dioxide for site performance and risk assessment studies at the reservoir scale. However, due to the restriction in computational time and resources, reservoir scale models have limitations in accounting for the multi-scale heterogeneities. In order to address the heterogeneity issues, appropriate upscaling methods are needed. In this study, we present macro-scale capillary pressure – relative permeability – saturation relationships for grid-block properties used in the full-scale modeling. We develop a macroscopic percolation model for the upscaling procedures. The macro-scale constitutive relationships are obtained through simulation procedures of CO2 displacing brine in a porous domain with spatially correlated random permeability fields. Sensitivity of the derived constitutive relationships to the statistical parameters representing the local heterogeneity is shown. Comparison of the percolation-based method to other approaches is demonstrated.
|
|
