Molson J W, Frind E O, Van Stempvoort D R, Lesage S
Department of Earth Sciences, University of Waterloo, ON, Canada.
J Contam Hydrol. 2002 Feb;54(3-4):277-305. doi: 10.1016/s0169-7722(01)00181-4.
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.
本系列第1部分所述的腐殖酸强化修复柴油的中试规模实验，在三维空间中进行了数值模拟。采用有限元伽辽金方法求解地下水流、柴油源的强化溶解以及溶解污染物和腐殖酸载体的反应输运。通过比较1500天监测期内7种柴油燃料成分（BTEX以及甲基萘、二甲基萘和三甲基萘）的观测浓度和模拟浓度，对模型（BIONAPL）进行了校准。来自辅助小型试验的数据用于估算污染物-载体结合系数，并模拟载体在含水层砂上的双位点吸附。该模型准确再现了腐殖酸导致三甲基萘表观溶解度增加10倍的情况。模拟得出甲基萘和二甲基萘的溶解度分别增加2至5倍。在实验和模拟条件下，残留的500毫升柴油源在5年内几乎完全溶解并降解。模拟结果表明，若无腐殖酸冲洗，柴油源完全溶解所需时间将约为原来的6倍。
