United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(510ZW)
EPA 542-N-94-001
February 1994
&EPA
The Applied Technologies Journal for Superfund Removals and Remedial Actions and RCRA Corrective Actions
Constructed wetlands as a treatment
technology for toxic metal contaminated
waters was effective in treating dis-
charge of acid mine drainage from the
Big Five Tunnel site near Idaho Springs,
Colorado. The technology was evalu-
ated under EPA s SITE (Superfund In-
novative Technology Evaluation)
Emerging Technology Program. An at-
tractive feature of this technology is that,
as a passive treatment system, the cost
of operation and maintenance is signifi-
cantly lower than that for active treat-
ment processes.
Constructed wetlands use natural
geochemical and biological processes
inherent in a wetland ecosystem to ac-
cumulate and remove metals from in-
fluent waters. The treatment system
incorporates organic substrates
Constructed Wetlands Remove Toxic Metals
from Acid Mine Drainage
by Edward R. Bates, Risk Reduction Engineering Laboratory
Metals
| Wetlands
Mine
Drainage
(synthetic soils), microbial fauna and
sometimes algae and vascular plants.
The removal methods try to utilize,
rather than overcome, natural processes.
From studies at Big Five Tunnel, it was
determined that the important processes
for raising the pH and removing metals
were microbial sulfate reduction fol-
lowed by precipitation of metal sulfides.
Once it was found that microbial
(see Wetlands, page 2)
Conference Alert
EPA's 5th, Forum on Innovative Haz-
ardous Waste Treatment Technolo-
gies; Domestic & International will t>e
at the Congress Hotel/ Chicago, Illi-
nois, on May 3-5,1994, Using techni-
cal paper and paster presentations/
this 3-day conference will introduce
and highlight innovative treatment
technologies having actual perfor-
mance f e$-i4t$. It wfll showcase results
of selected international technologies,
the y£. EPA Superfvtnd innovative
Technology Evaluation ($ITB) Pro-
gram technologies and case studies
irom &ose using innovative technolo-
gies. The overall objective is to in-
crease the awareness of the user
community of technologies ready for
application at clean-up sites.
For more information contact:
SAIC, Technology Transfer Depart*
atent, 501 Office Center Drive, Suite
420, Ft. Washington, PA 19034 The
numbers &te: 800-783-3870 (toll fr«e);
215-628-9317 (in PA); 215-628-8916
(FAX). •
Superfund Remedial Actions
Project Status of Innovative Treatment Technologies
as of June 1993
Technology
Predesign/
In Design
Design Complete/
Being Installed/
Operational
Project
Completed
Total
Soil Vapor Extraction 69 32 6 107
Ex situ Bioremediation 22 11 1 34
Thermal Desorption 20 8 4 32
In situ Bioremediation* 16 9 1 26
Soil Washing 17 3 0 20
In situ Flushing 16 4 0 20
Dechlorination 3 1 1 5
Solvent Extraction 5005
In situ Vitrification 3003
Chemical Treatment 7103
Other Innovative Treatment 2018
TOTAL 180 (69%) 69 (26%) 14 (5%) 263
Note: Data are derived from 1982-1992 Records of Decision (RODs) and antici-
pated design and construction activities as of June 1993.
* Also includes in situ groundwater treatment.
Printed with Soy/Canola ink on paper that contains
at least 50% post-consumer recycled fiber
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New
X-Ray Fluorescence Lead Survey
The report, An X-ray Fluorescence Sur-
vey of Lead Contaminated Residential
Soils in Leadville, Colorado: A Case
Study, presents information on the use
of field-portable X-ray fluorescence
(FPXRF) to determine the spatial distri-
bution of lead concentrations in residen-
tial soils contaminated from the
California Gulch Superfund site in
Leadville, Colorado. The report details
the FPXRF program sample collection,
preparation and analysis procedures,
database management and program
quality assurance efforts at Leadville.
The program clearly demonstrates that
small field portable X-ray fluorescence
instrumentation can produce large
quantities of acceptable quality data in a
timely and cost-efficient manner. When
combined with the results of blood lead
level and bioavailability studies, these
data can help to develop a true assess-
ment of the risks
The report can be ordered from
EPA s CERI at 513-569-7562. When or-
dering, please refer to the Document
Number: EPA/600/R-93/073.
Wetlands, from page /
processes were primarily responsible
for contaminant removal, it was realized
that establishing and maintaining the
proper environment in the substrate is
the key to success for removal. Labora-
tory studies determined the best sub-
strate combination for removal of the
contaminants. Bench scale studies deter-
mined the optimum loading capacity
and treatment system configuration.
A staged design process comparable
to the design process used for other
wastewater treatment technologies was
conceived.
First, it was decided that a trickling
filter type of configuration achieved the
best contact of the water with the sub-
strate. Influent waters flowed through
the aerobic and anaerobic zones of the
wetland ecosystem. Metals were re-
moved by filtration, ion exchange and
chemical and microbial oxidation and
reduction. In filtration, metal flocculates
and metals that were adsorbed onto fine
sediment particles settled in quiescent
ponds or were filtered out as the water
percolated through the soil or the plant
canopy. Ion exchange occurred as met-
als in the water came into contact with
humic or other organic substances in the
soil medium. Oxidation and reduction
reactions that occurred in the aerobic
and anaerobic zones, respectively,
played a major role in removing metals
as hydroxides and sulfides.
Removal efficiency depended
strongly on permeability and loading
factors. Permeability of the substrate
was found to be a critical design
variable for successful operation in or-
der to avoid hydraulic short-circuiting
of the substrate and incomplete treat-
ment. For the Big Five Tunnel studies, it
was found that the loading factor of the
influent should not exceed the 300
nanomoles/cm3/day of sulfide gener-
ated by the microbes in the substrate.
By optimizing the process and deter-
mining how to properly load the wet-
land with contaminated drainage, the
following results were achieved at Big
Five Tunnel. The pH was raised from
2.9 to 6.5. Dissolved Cu, Zn, Cd, Ni and
Pb concentrations were reduced by 98%
or more. Iron removal was seasonal
with 99% reduction in the summer. Mn
reduction was relatively poor unless the
pH of the effluent was raised above 7.0.
Biotoxicity to fathead minnows and
Ceriodaphnia was reduced by factors of 4
to 20 times. The initial concentration of
metal contaminants had been high with
Mn, 31 milligrams per liter (mg/L); Fe,
38 mg/L; Co, 0.10 mg/L; Ni, 0.15 mg/
L; Cu 0.73 mg/L; Zn, 9.4 mg/L; Cd, 0.03
mg/L; and Pb, 0.03 mg/L.
As with any other wastewater re-
moval technology, design of a con-
structed wetland or passive bioreactor is
specific to the site and the water to be
treated. For each site a staged design
and development sequence similar to
Big Five Tunnel should be planned
which would include: laboratory stud-
ies to determine the best conditions and
substrate; bench scale experiments to
determine loading factors and substrate
properties, including permeability; and
pilot modules to test the performance of
a typical field module.
In addition to treatment of acid mine
drainage from metal or coal mining ac-
tivities, the wetlands process is also suit-
able for leachates or wastewater that are
mildly acidic or mildly alkaline and
contain toxic metals. The technology has
been applied with some success to
wastewater in the eastern regions of the
United States. The process may have to
be adjusted to account for differences in
geology. Constructed wetlands have
been selected in Records of Decision for
portions of the Clear Creek Site in Colo-
rado and the Buckeye Landfill Site in
eastern Ohio. Also, the SITE program is
doing large-scale demonstration at the
Burleigh Mine Tunnel on the Clear
Creek site.
A complete report on the constructed
wetlands technology entitled, A Hand-
book for Constructed Wetlands Receiving
Add Mine Drainages (Order No. PB93-
233914AS), is available at a cost of
$36.50 (paper) and $17.50 (microfiche)
from: National Technical Information
Service, 5285 Port Royal Road, Spring-
field, VA 22161 (phone: 7034874650).
A shorter summary report, Emerging
Technology Summary: Handbook for Con-
structed Wetlands Receiving Acid Mine
Drainage (Document No. EPA/540/SR-
93/523), is available at no cost and can
be ordered by calling EPA s Center for
Research Information (CERI) at
513-569-7562.
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SITI?
Jm 11»
Mobile Soil Washing Unit Rids Soils of VOCs
by Teri Richardson, Risk Reduction Engineering Laboratory
VOCs
Soil
| Washing
Soil
The mobile Volume Reduction Unit
(VRU) is a cost effective soil washing
technology that rids soils of organic
contaminants by suspending them in a
wash solution and by reducing the vol-
ume of contaminated material through
particle size separation. The VRU was
developed by EPA s Risk Reduction En-
gineering Laboratory (RREL) and evalu-
ated in a SITE (Superfund Innovative
Technology Evaluation) Program dem-
onstration at the Escambia Wood Treat-
ing Company Superfund Site in
Pensacola, Florida. The 26-acre facility,
now closed, used pentachlorophenol
(PCP) and creosote-fraction polynuclear
aromatic hydrocarbons (PAHs) to treat
wood products from 1943 to 1982.
Initial feed soil concentrations, after
homogenization and screening, ranged
from 43 to 200 parts per million (ppm)
for PCP and 480 to 1,500 ppm for PAHs.
The demonstration found that removal
efficiency was clearly enhanced by sur-
factant addition and pH and tempera-
ture adjustment, yielding an average of
97% PCP removal and 96% removal for
PAHs. Treatment costs appear to be
competitive with other available tech-
nologies. The cost to remediate 20,000
tons of contaminated soil using a 10
tons per hour VRU is estimated at $130
per ton if the system is on-line 90% of
the time. Treatment costs increase as the
percent on-line factor decreases. Pro-
jected unit costs for a smaller site
(10,000 tons of contaminated soil) are
$163 per ton; projected unit costs for a
larger site (200,000 tons) are $101 per
ton.
For this demonstration, the VRU was
composed of two segments: soil wash-
ing and water treatment. The soil wash-
ing segment produced fines slurry and
washed soil streams. The water treat-
ment segment treated the fines slurry by
separating the fines and removing pol-
lutants from the wash water through a
series of steps including sedimentation,
flocculation, filtration and carbon ad-
sorption. An additional series of unit
operations, such as a trommel washer
and dispersing agent (e.g., sodium
hexametaphosphate) employed after
vibrascreens, may help reduce the level
of fines in washed soil even
further.
The VRU system consistently and
successfully segregated the contami-
nated soil into two unique streams:
washed soil and fines slurry. The
washed soil was safely retuned to the
site with no further treatment. The tar-
get cleanup levels were 30 ppm PCP, 50
ppm carcinogenic creosote and 100 ppm
total creosote. Under conditions where
surfactants were added and pH and
temperature were adjusted, the washed
soil contaminated concentrations
dropped to 3 ppm PCP, 2.8 ppm carci-
nogenic creosote and 38 ppm total creo-
sote.
The VRU system appeared not to be
adversely affected by fluctuations in
feed rate, wash water-to-feed ratio,
wash water additives or other operating
parameters. One of the primary objec-
tives of the SITE demonstration was to
determine whether or not the VRU
could recover 80% of the volume of con-
taminated feed soil as clean washed soil.
Greater than 80% soil recovery was
achieved.
The VRU s effectiveness is based on
its ability to separate soil fines (less than
100 mesh) from the coarser gravel and
sand fraction of the soil (greater than
100 mesh). Significant contaminant con-
centration reductions can be realized by
the VRU, provided the majority of the
contaminants present in the feed soil
concentrate in the fines. The data indi-
cate the majority of the small particles
were partitioned to the fines slurry.
Only 1% to 2% of the large (greater than
100 mesh) particles were detected in the
fines slurry. For the SITE demonstra-
tion, 10 mesh [2 millimeter (mm)] and
100 mesh (0.15 mm) separating screens
were used.
Treated water from the VRU is po-
tentially suitable for recycling as wash
water, but it would likely require fur-
ther treatment before being recycled. If
the treated water cannot be reused as
wash water, then it must be disposed of
in accordance with applicable discharge
requirements.
For more information, call Teri
Richardson at EPA s RREL at 513-569-
7949. Also, a six-page Technology
Demonstration Summary (Document
No. EPA/540/SR-93/508, and two de-
tailed reports Applications Analysis Re-
port (Document No. EPA/540/AR-93/
508) and Technology Evaluation Report
(Document No. EPA/540/R-93/508)
can be ordered from the Center for En-
vironmental Research Information
(CERI) by calling 513-569-7562.
Public Meetings on Technology Innovation Strategy
EPA is hosting two public meetings in April to discuss the draft Technology Innovation Strategy (see p. 4). The April 6,1994,
meeting is from 9:00 a.m. to 4:00 p.m. at Sheraton Gateway Suites, 6501 N. Manheim Road, Chicago, Illinois 60018 (phone:
708-699-4300). The April 12,1994, meeting is from 9:00 a.m. to 4:00 p.m. at the Ramada Renaissance Hotel, 13869 Park Cen-
ter Road, Hemdon, Virginia 22017 (phone: 703-478-2900). For more information, call Brendan Doyle at 202-260-3354.
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EPA Administrator Browner launches
Innovative Technology Initiative
EPA Administrator Carol M. Browner
announced a major new initiative to
back up her stated goals to establish
procedures that allow EPA labs to be
used to test and evaluate innovative
technologies developed outside EPA
and to expand the Agency s coopera-
tive programs for developing, testing
and evaluating specific categories of in-
novative technologies. The goal of the
Environmental Technology Initiative
(ETI) is to spur the development and
use of more advanced environmental
systems and treatment techniques that
can be used in the United States and
abroad. The ETI is funded at $36 million
in FY 1994 and, in the Presidents plan,
is to be funded at $80 million in FY
1995, with overall funding to be 1.8 bil-
lion over nine years.
In 1994, EPA has selected 73 projects
that will be implemented with other
partners including: Federal agencies,
States, nonprofit groups and the private
sector. Two of the projects that are being
funded in 1994 are the Consortium for
Site Characterization Technology
(CSCT) and the LASAGNA Cooperative
Research and Development Agreement
(CRADA).
CSCT. The CSCT will provide and
implement a performance validation
process for innovative characterization
technologies. The CSCT will be a multi-
agency effort which will triage environ-
mental monitoring needs so that
technology developers will have guid-
ance in meeting regulatory needs. It will
also provide the users with credible per-
formance information and methods.
This program differs from the SITE pro-
gram in the inclusion of other Federal
agencies, such as the U.S. Department of
Defense, U.S. Department of Energy
and State regulators. The CSCT will pro-
vide different review and evaluation
mechanisms from those currently used
by SITE. The goal of the CSCT is the
streamlining of the development, evalu-
ation, acceptance and use of innovative
site characterization technologies that
meet performance-based criteria. EPA s
Environmental Monitoring Systems
Laboratory at Las Vegas (EMSL-LV) is
active in the formation and coordination
of the CSCT, with support from EPA?
Office of Solid Waste and Emergency
Response, Office of Federal Facilities
Enforcement and Regions. For further
information on the CSCT, contact Eric
Koglin, Technology Transfer Officer at
EMSL-LV (702-798-2432).
CRADA. On January 27, EPA Adminis-
trator Browner signed a CRADA with
Monsanto, DuPont and General Electric
companies to kick off a pilot project to
develop and field test a new technology
to treat contaminated dense (clay-like)
soil. Dubbed the lasagna process, it
involves the use of an electrical field to
draw contaminants into layered areas
called treatment zones, created by soil
fracturing. This method is designed to
treat soil and ground water contami-
nants completely in place and be more
effective than traditional waste
remediation methods. This process
could have widespread use in cleaning
up hazardous waste sites and thus in re-
ducing human exposure to hazardous
waste. For further information contact
Larry Fradkin at 513-569-7960.
Periodically, we will update you on
the activities and products of these and
other remediation-related projects
funded under the ETI.
To order additional copies of this or previous issues of Tech Trends, or to be included on the permanent mailing list, send a fax
request to the National Center for Environmental Publications and information (NCEPI) at 513-891-6685, or send a mail request to NCEPI,
11029 Kenwood Road, Building 5, Cincinnati, OH 45242-0419. Please refer to the document number on the cover of the issue if available.
Tech Trends welcomes readers' comments and contributions. Address correspondence to: Managing Editor, Tech Trends (5102W),
U.S. Environmental Protection Agency, 401 M Street, S.W., Washington, DC 20460.
United States
Environmental Protection Agency
National Center for Environmental
Publications and Information
P.O. Box 42419
Cincinnati, OH 45242-0419
Official Business
Penalty for Private Use $300
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