vvEPA
                               United States
                               Environmental Protection
                               Agency
              EPA/540/F-95/509
              August 1995
                               SUPERFUND INNOVATIVE
                               TECHNOLOGY  EVALUATION
                  Emerging Technology  Bulletin

              Process for the Treatment of Volatile Organic Carbon and
                               Heavy-Metal-Contaminated Soil
                               International Technology Corporation
Technological  Description:  The  batch steam distillation and
metal extraction treatment process is a two-stage system that
treats soils contaminated with  organics and inorganics. This sys-
tem uses conventional, readily available  process equipment, and
does  not produce hazardous combustion products. Hazardous
materials are separated  from soils as concentrates, which can
then be disposed of or recycled. The treated soil can be returned
to the site.

During treatment, waste soil is slurried  in water and heated to
100 degrees Celsius. This heat vaporizes volatile  organic com-
pounds (VOC) and produces  an amount of steam  equal to 5 to
10 percent of the slurry volume. Resulting vapors are condensed
and decanted to separate organic contaminants from the aque-
ous phase. Condensed  water from this step can be recycled
through the system after further treatment to remove soluble
                       Recycle water from
                       extraction step
organics. The soil is then transferred as a slurry to the metals
extraction step.

In the metals extraction step, the soil slurry is washed with
hydrochloric acid. Subsequent countercurrent batch washing with
water removes residual acid from the soil. The solids are then
separated from the final1 wash solution by gravimetric sedimen-
tation. Most heavy metals are converted to chloride salts in this
step. The acid extract stream is then routed to a batch distillation
system, where excess hydrochloric acid is recovered (see figure
below).  Bottoms from the still, which contain  heavy metals, are
precipitated as hydroxide  salts and drawn off as a sludge for
offsite disposal or recovery.

As a batch process, this treatment technology is targeted at sites
with less than 5,000 tons of soil requiring treatment. Processing
                                                                          Offsite disposal
                                                                         Soil slurry to
                                                                         metal extraction
                                                                         or dewatering vessel
                                     Batch distillation vessel
 Figure 1. Batch steam distillation step.
                                                                                   Printed on Recycled Paper

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time depends on equipment size and batch cycle times; roughly
one  batch of soil can be treated every four hours.  Estimated
treatment costs per ton, including capital recovery, for the two
treatment steps are as follows:
Batch Steam Distillation
                500-ton site
                2,500-ton site
Metals Extraction
(including add recovery)
                500-ton site
                2,500-ton site
$299-393/ton
$266-350/ton
$447-619/ton
$396-545/ton
Waste Applicability:  This process may be applied to soils and
sludges contaminated with organics, inorganics, and heavy met-
als,

Results: The batch steam distillation and metal extraction  pro-
cess was accepted into the SITE-Emerging Technology-Program
In January 1988. Under the program, three pilot-scale tests have
been completed  on three soils, for a total of nine tests.  The
removal rates for benzene,  toluene, ethylbenzene, and xylene
were greater than 99 percent. The removal rates for chlorinated
solvents ranged from 97 percent to 99 percent.

One acid  extraction and two  water washes  resulted in a 95
percent removal  rate for heavy metals. Toxicity characteristic
leaching procedure tests on the treated soils showed that soils
from eight of the nine tests met leachate criteria. Data were  also
collected on the recovery rate for excess acid and  the removal
rate for precipitation of heavy metals into a concentrate.

For Further Information:

EPA Project Manager:
Ronald Lewis
U.S. EPA
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7856
Rax: 513-569-7620				  =   - -
 United States
 Environmental Protection Agency
 National Risk Management Research Laboratory (G-72)
 Cincinnati, OH 45268

 Official Business
 Penalty for Private Use
 $300
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                                                    POSTAGE & FEES PAID
                                                             EPA
                                                       PERMIT No. G-35
 EPA/S40/F-95/S09

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