Remediation of solvent-contaminated soils by aeration
Kempton, H. | Davis, A. | Olsen, R.
A bench-scale box test was performed to evaluate the feasibility of rototilling to remediate excavated soils contaminated with tetrachloroethylene (PCE), trichloroethylene (TCE), and 1,1,1-trichloroethane (1,1,1-TCA). Two clay-rich soils (A and B) containing 0.15% organic C and different concentrations of the target analytes were placed in 15-cm thick layers under a 10 km/h wind, tilled daily, and samples collected and analyzed periodically. Soil A (25,000 microgram/kg PCE) lost 80% after 24 h and 97% after 407 h. Soil B (8881 microgram/kg PCE) lost 29% after 24 h and 92% after 407 h. Initial TCE and 1,1,1-TCA concentrations ranged from 793 to 1570 microgram/kg. Relative volatilization loss rates were similar to that of PCE. The average volatilization half-lives of the solvents were 1.2 d for PCE, 0.58 d for TCE, and 0.64 d for 1,1,1-TCA. Removal of the analytes slowed considerably after 200 h, with a small (up to 10%) amount of each analyte retained in refractory sites. Residual solvent concentrations in soils A and B after 407 h were 935 and 719 microgram/kg PCE, 38 and 95 microgram/kg TCE, and 21 and 31 microgram/kg 1,1,1-TCA. Simulations of volatilization using the pesticide root zone model (PRZM) accurately predicted the loss or PCE, TCE, and 1,1,1-TCA over the first 24 h when most of the solvent volatilized, but the model overpredicted contaminant losses at longer durations when remnant soil concentrations were less than six times the concentration bound to refractory sites.
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