Humic acid enhanced remediation of an emplaced diesel source in groundwater. 2. Numerical model development and application.
A pilot scale experiment for humic acid-enhanced remediation of diesel fuel, described in Part 1 of this series, is numerically simulated in three dimensions. Groundwater flow, enhanced solubilization of the diesel source, and reactive transport of the dissolved contaminants and humic acid carrier are solved with a finite element Galerkin approach. The model (BIONAPL) is calibrated by comparing observed and simulated concentrations of seven diesel fuel components (BTEX and methyl-, dimethyl- and trimethylnaphthalene) over a 1500-day monitoring period. Data from supporting bench scale tests were used to estimate contaminant-carrier binding coefficients and to simulate two-site sorption of the carrier to the aquifer sand. The model accurately reproduced the humic acid-induced 10-fold increase in apparent solubility of trimethylnaphthalene. Solubility increases on the order of 2-5 were simulated for methylnaphthalene and dimethylnaphthalene, respectively. Under the experimental and simulated conditions, the residual 500-ml diesel source was almost completely dissolved and degraded within 5 years. Without humic acid flushing, the simulations show complete source dissolution would take about six times longer.
Molson
J W
JW
Department of Earth Sciences, University of Waterloo, ON, Canada. molson@uwaterloo.ca
Frind
E O
EO
Van Stempvoort
D R
DR
Lesage
S
S
D001673:Biodegradation, Environmental; D005742:Gasoline / Q000032:analysis*; D006812:Humic Substances / Q000737:chemistry*; D008962:Models, Theoretical; D012822:Silicon Dioxide; D012989:Soil Pollutants / Q000378:metabolism*; D012995:Solubility; D014872:Water Movements; D014873:Water Pollutants / Q000378:metabolism*
D005742:Gasoline; D006812:Humic Substances; D012989:Soil Pollutants; D014873:Water Pollutants; D012822:Silicon Dioxide