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PILOT-SCALE SUBCRITICAL WATER REMEDIATION OF POLYCYCLIC AROMATIC HYDROCARBON- AND PESTICIDE-CONTAMINATED SOIL. (R825394)
Citation:
Lagadec, A. J., D. J. Miller, A. V. Lilke, AND S. B. Hawthorne. PILOT-SCALE SUBCRITICAL WATER REMEDIATION OF POLYCYCLIC AROMATIC HYDROCARBON- AND PESTICIDE-CONTAMINATED SOIL. (R825394). ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 34:1542-1548, (2000).
Description:
Subcritical water (hot water under enough pressure to maintain the liquid
state) was used to remove polycyclic aromatic hydrocarbons (PAHs) and pesticides
from highly contaminated soils. Laboratory-scale (8 g of soil) experiments were
used to determine conditions for the pilot-scale (8 kg of soil) extractions.
Pilot-scale remediations of a PAH-contaminated manufactured gas plant soil (2200
ppm total PAHs ranging from naphthalene to benzo[ghi]perylene) with 275 
C water reduced all low and high molecular
weight PAHs to below detectable levels (<0.5 ppm) in as little as 35 min. In
contrast, removals of higher molecular weight (mutagenic) PAHs were much poorer
with either bioremediation for 1 year or supercritical carbon dioxide
extraction. Subcritical water extraction at 250 src="/ncer/pubs/images/deg.gif">C of 8 kg of soil contaminated with 70-400
mg/kg levels each of trifluralin, atrazine, cyanazine, pendimethalin, alachlor,
and metolachlor also removed all pesticides to below detection limits. While
neither the PAH- or pesticide-contaminated soils could support plant growth
before extraction, both soils were fertile without additional treatment after
extraction (based on germination of lettuce, radishes, and corn); and earthworm
toxicity was reduced from 100% to 0%.