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Soil heterogeneity effects on acid flushing of lead-contaminated soil

Nakagawa, Kei; Wada, Shin-Ichiro; Momii, Kazuro Momii and Berndtsson, Ronny LU (2008) In Environmental Modelling and Assessment 13. p.121-134
Abstract
A compact model for evaluation of acid flushing of heavy-metal-contaminated soil in a small-scale on-site treatment plant is proposed. The model assumes that the soil was re-packed in a container after excavation resulting in a soil structure with heterogeneous and random physical and chemical properties. To evaluate the effects of heterogeneity on the efficiency of contaminant removal by acid flushing, a numerical analysis of lead transport in the heterogeneous soil medium was performed. The model examines cation exchange and surface complexation reactions involving three cations (Ca, Pb, and H) and one anion (Cl) in both dissolved and exchangeable forms, two Pb surface complexes (SOPbCl and SOPbOH), and one Cl surface complex (SOH2Cl).... (More)
A compact model for evaluation of acid flushing of heavy-metal-contaminated soil in a small-scale on-site treatment plant is proposed. The model assumes that the soil was re-packed in a container after excavation resulting in a soil structure with heterogeneous and random physical and chemical properties. To evaluate the effects of heterogeneity on the efficiency of contaminant removal by acid flushing, a numerical analysis of lead transport in the heterogeneous soil medium was performed. The model examines cation exchange and surface complexation reactions involving three cations (Ca, Pb, and H) and one anion (Cl) in both dissolved and exchangeable forms, two Pb surface complexes (SOPbCl and SOPbOH), and one Cl surface complex (SOH2Cl). The transport of these species during flushing with acid in a synthetically generated two-dimensional heterogeneous soil was simulated in the model. Results indicated that the flushing fluid preferentially followed pathways with large permeability. The heterogeneous cation exchange capacity (CEC) distribution and surface complexation sites had a significant effect on the transport of dissolved species. Because the CEC was set to a relatively low value, Pb was adsorbed mainly as surface complexes (SOPbCl and SOPbOH). Simulation results suggest that blocks of low hydraulic conductivity located in the upper part of the model domain greatly impede solute transport. Ponding conditions did not significantly affect the efficiency of decontamination. The model and its results are useful in the design of small-scale treatment plants for acid flushing. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
numerical simulation, lead-contaminated soil, acid flushing, cation exchange, surface complexation
in
Environmental Modelling and Assessment
volume
13
pages
121 - 134
publisher
Springer
external identifiers
  • wos:000252418500009
  • scopus:38349095880
ISSN
1573-2967
DOI
10.1007/s10666-006-9076-0
language
English
LU publication?
yes
id
6d176622-91bc-40fd-8d3d-fd412c681fcd (old id 587390)
date added to LUP
2007-12-01 12:52:57
date last changed
2017-01-01 04:27:50
@article{6d176622-91bc-40fd-8d3d-fd412c681fcd,
  abstract     = {A compact model for evaluation of acid flushing of heavy-metal-contaminated soil in a small-scale on-site treatment plant is proposed. The model assumes that the soil was re-packed in a container after excavation resulting in a soil structure with heterogeneous and random physical and chemical properties. To evaluate the effects of heterogeneity on the efficiency of contaminant removal by acid flushing, a numerical analysis of lead transport in the heterogeneous soil medium was performed. The model examines cation exchange and surface complexation reactions involving three cations (Ca, Pb, and H) and one anion (Cl) in both dissolved and exchangeable forms, two Pb surface complexes (SOPbCl and SOPbOH), and one Cl surface complex (SOH2Cl). The transport of these species during flushing with acid in a synthetically generated two-dimensional heterogeneous soil was simulated in the model. Results indicated that the flushing fluid preferentially followed pathways with large permeability. The heterogeneous cation exchange capacity (CEC) distribution and surface complexation sites had a significant effect on the transport of dissolved species. Because the CEC was set to a relatively low value, Pb was adsorbed mainly as surface complexes (SOPbCl and SOPbOH). Simulation results suggest that blocks of low hydraulic conductivity located in the upper part of the model domain greatly impede solute transport. Ponding conditions did not significantly affect the efficiency of decontamination. The model and its results are useful in the design of small-scale treatment plants for acid flushing.},
  author       = {Nakagawa, Kei and Wada, Shin-Ichiro and Momii, Kazuro Momii and Berndtsson, Ronny},
  issn         = {1573-2967},
  keyword      = {numerical simulation,lead-contaminated soil,acid flushing,cation exchange,surface complexation},
  language     = {eng},
  pages        = {121--134},
  publisher    = {Springer},
  series       = {Environmental Modelling and Assessment},
  title        = {Soil heterogeneity effects on acid flushing of lead-contaminated soil},
  url          = {http://dx.doi.org/10.1007/s10666-006-9076-0},
  volume       = {13},
  year         = {2008},
}