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/A newsletter about soil, sediment, and ground-water characterization and remediation technologies
September 2005
Issue 20
member of the interagency National Nanotechnology Initiative, the U.S. Environmental
Protection Agency (EPA) is helping to coordinate research and development of nanoscale
science, engineering, and technology. In this role, EPA also is studying the potential risks posed
by manufactured nanomaterials due to their composition, reactivity, and unique size. This issue
o/Technology News and Trends focuses on emerging nanotechnologies applicable to hazard-
ous waste characterization and remediation.
Monitoring Shows Enhanced Abiotic Degradation of TOE DNAPL
Resulting from Emulsified ZVI Injection
The National Aeronautics and Space
Administration (NASA) has compiled nearly
three years of monitoring data from the first
field-scale demonstrationto evaluate nanoscale
emulsified zero-valent iron (EZVT) injections
used for enhancing in-situ dehalogenation of
dense, nonaqueous-phase liquid (DNAPL).
Collaborating with researchers from the
University of Central Florida and EPA, NASA
initiated the project as part of a multi-prong
effort to treat extensive areas of subsurface
trichloroethene (TCE) contamination at Cape
Canaveral Air Force Station, FL. The
demonstration results show that this emerging
technology has the potential to effectively
treat DNAPL source zones and suggests
capability for treating dissolved-phase
contaminants in the vicinity of DNAPL.
EZVT technology capitalizes on the ability of
food-grade surfactant, biodegradable
vegetable oil, water, and ZVI to form
hydrophobic emulsiondroplets tot ate miscible
withDNAPL (Figure 1). Chlorinated volatile
organic compounds (VOCs) in DNAPL
diffuse through the oil membrane and undergo
reductive dechlorination in the presence of
ZVI inthe interioraqueous phase. Encapsulating
ZVT in a hydrophobic membrane protects the
nanoscale iron from other ground-water
constituents such as inorganics that might
otherwise use some of the iron's reducing
capacity, and thereby reduces the mass of
EZ VI available to treat target contaminants
and overall project costs. Additionally, EZVTs
vegetable oil and surfactant components enable
the material to serve as a long-term electron
donor and promote anaerobic biodegradation.
The demonstration was conducted in a 15- by
9.5-foot area below a building at Launch
Complex 34. Pre-demonstration soil cores
showed the presence of TCE in concentrations
exceeding 250 mg/kg. EZVI was injected
throughout a 10-foot-thick zone within the upper
sand unit of the site's surficial aquifer system.
The upper sand unit comprises medium- to
coarse-grained sand and crushed shells and
extends from the ground surface to
approximately 18-25 feet below ground
surface (bgs). The water table fluctuates from
3 to 7 feet bgs, withhydraulic gradients ranging
from 0.09'3 ft/ft to 0.072 ft/ft.
Primary objectives of the demonstration test
were to estimate changes in total TCE mass
and TCE DNAPL mass in the target unit as well
as changes in TCE flux to ground water. Atotal
of 21 ground-water monitoring points were
established within a system composed of a fully
screened well and four monitoring wells with
five sample intervals. Two additional monitoring
wells were installed to obtain measurements at
three depth intervals outside the treatment zone.
A ground-water control system with activated
carbon was installed to create a closed-loop
recirculation cell and forced gradient conditions
[continued on page 2]
Contents
Monitoring Shows
Enhanced Abiotic
Degradation of TCE
DNAPL Resulting from
Emulsified ZVI Injection
EPA Targets Key Areas
of Nanotechnology
Research
page 1
page 3
High Specificity of Metal
Detection Achieved by
Nanocontact and Polymer
Nanojunction Sensors page 3
Bimetallic ZVI Technology
Implementation Expands
to Remediate VOC Hot
Spots in Ground Water page 4
Microscale Metal
Sorbents Approach
Commercial Use page 5
Federal Agencies
Partner in Upcoming
Nanotechnology
Workshop page 6
Nanotechnology
Resources
Within the framework of the
National Science and Technol-
ogy Council, the National
Nanotechnology Initiative (NNI)
oversees nanoscale research
and development among 23
federal agencies. The NNI aims
to maximize the potential of
nanotechnology, facilitate
nanotechnology transfer,
develop education resources
and an infrastructure for
nanotechnology advancement,
and oversee responsible
development of nanotechnology.
More information is available at
http://www.nano.gov.
Recycled/Recyclable
Printed with Soy/Canola Ink on paper thai
contains at least 50% recycled fiber
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[continued from page 1]
across the treatment zone. The system
operatedforthree weeks priorto the injection
to allow for post-injection evaluation of flux
caused by the treatment process. Along with
baseline ground-water and soil quality
parameters, pre-demonstration sample sets
were measured for interfacial surface tension
between EZVI and water, TCE and water,
and EZVI, TCE, and water
EZVT was introduced to the aquifer during a
single injection occurring over five days in
October 2002. Based on earlier laboratory
evaluations, the selected injectant contained
44.3% water, 37.2% oil, 1.5% surfactant,
and 17% (100 to 200 nm-sized particle) iron
by weight. The mixture was injected into eight
3 inch-diameterwellsatinjectionintervalsof
16-20 and 20-24 feet bgs using pressure pulse
technology. Atotal of 670 gallons of the EZVI
mixture was injected. To enhance distribution
ofEZVT into the formation, additional ground
water from a treatment zone monitoring well
was added at the injection points.
Visual observation of four interim soil cores
obtained two months after the injection, as
well as laboratory analysis of six soil cores
collected three months after injection,
confirmed that EZVI reached some target
areas but missed others and migrated upward
from the treatment zone. The ground-water
recirculation system operated for a three-
week period five months after the injection
in order to evaluate changes in contaminant
concentrations and mass flux. To evaluate
longer-term impacts of treatment, additional
ground-water analytical samples were
collected 19and22 months afterthe injection
As anticipated, the demonstration results
indicated that EZVI was miscible with the
DNAPL and caused little downward
movement of DNAPL. Analysis of soil
samples showed an 80% average reduction
of TCE concentration within 90 days at all
but two boring locations, apparently due to
upward migration of EZVI. The maximum
individual reduction was noted in a soil
boring taken at a depth of 16-18 feet, where
the TCE concentration decreased from 6,067
to 1 mg/kg following treatment.
Geostatistical analysis indicated 58-85%
reductions intotal TCE andTCEDNAPL mass
from initial pre-treatment estimates of 17.8 kg
and 3.8 kg, respectively, in the upper sand unit.
Analysis of TCE in ground-water samples
collected from wells located in the center and
downgradient portions of the treatment area
indicated 57-100% reductions of TCE at all
targeted depths and significant reductions in
TCE degradation products. A maximum
individual reduction was noted in ground water
collected from a single well at a depth of
23.5 feet, where the TCE concentration
decreased from 700 mg/L to less than
1.0 mg/L following treatment.
Analysis of TCE and bio degradation
products suggested that TCE reductions in
the demonstration area were caused by
contaminant destruction rather than
mobilization Mass flux for a downgradient
transect decreased approximately 56%, from
19.2 to 8.5 mmol/day/ft2 over a period of 6
months. Slug tests within the treatment zone
indicated only a minor change in hydraulic
conductivity following treatment, from 43 ft/
day to 38 ft/day, likely due to iron oxide
buildup orbiofouling.
The relatively wide range in post-treatment
TCE concentrations suggested that EZVI was
distributed unevenly during the initial field-
scale injection. To address this problem, a
second field test was conducted in early 2004
to evaluate improved techniques for injectant
delivery: pneumatic fracturing, hydraulic
fracturing, pressure pulsing, and direct
injection Each of these technologies was
used to deliver 100 gallons of EZVI
containing nanoscale iron to depths of 16-
19-ft in an open field near the original
injection location. Results showed that
pneumatic injection and direct push
technology allowed for more controlled
injections without loss of EZVI above or
below the target region. Overall findings of
these tests recommend that full-scale
applications include preliminary testing to
confirm that planned injection methods do
not damage emulsion droplets during the
injection process.
Nearly three years of monitoring following
the demonstration suggests that
biodegradation enhanced by the presence of
oil and surfactant in the EZVI emulsion has
contributed to TCE reductions. Follow-on
EZVI tests under the U.S. Department of
Defense's Environmental Security
Technology CertificationProgram(ESTCP)
will evaluate the proportion of chlorinated
solvent mass destruction that occurs due to
abiotic degradation versus enhanced
biodegradation stimulated by the addition of
EZVI electron donors. The ESTCP project
also will continue to evaluate unresolved
issues associated with injection methods and
DNAPL mobilization potential.
Contributed by Jacqueline Quinn,
NASA (321-867-8410 or
Jacqueline, w. quinn&nasa. gov) and
Thomas Krug, GeoSyntec Consultants,
Inc. (519-822-2230 or
tkrus&seosvntec. com)
Water
Oil
Surfactant ooc>
Iron ^^~
Figure 1. EZVI technology
demonstrated at the NASA test site
employed emulsion droplets containing
nanoscale iron particles in water
surrounded by an oil-liquid membrane.
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EPA Targets Key Areas of Nanotechnology Research
Through its Office of Research and Development (ORD), the EPA's National Center for Environmental Research (NCER) has
funded 32 Science to Achieve Results (STAR) research grants for more than $11 million in the applications of nanotechnology to
protect the environment. The program focuses on developing low-cost, rapid, and simplified methods of removing contaminants
from surface water; new sensors that are more sensitive for measuring pollutants; green manufacturing of nanomaterials; and more
efficient and selective catalysts. An additional 12 STAR research projects are underway to study potentially harmful effects of
manufactured nanomaterials.
ORD also has awarded contracts to more than 20 small companies through its Small Business Innovation Research Program to
develop and commercialize nanomaterials and clean technologies. Current research projects in ORD laboratories are examining
topics such as the use of nanostructured photocatalysts as "green" alternatives to hydrocarbon oxygenation; nanomaterials as
adsorbents, membranes, and catalysts for air emission control; and ultrafine paniculate matter data for assessing impacts of
nanomaterial manufacturing. More information is available from the NCER at http://es.epa.gov/ncer.
High Specificity of Metal Detection Achieved by Nanocontact Sensors and Polymer Nanojunction
Researchers at Arizona State University
(ASU) are working under a STAR grant to
develop high-performance, low-cost
sensors for initial onsite screening of heavy
metals in ground and surface water. To
enhance field portability, the fully developed
sensors will be miniaturized and wireless
and employ a printed wire board capable of
integrating data collected from several
probes. Field testing of the prototype sensors
is anticipated in 2007.
Each sensor consists of an array of
nanoelectrode pairs on a silicon chip. Within
each pair, the nanoelectrodes are separated
by an atomic-scale gap created by quantum
tunneling (Figure 2). Electrochemical
deposition of only a few metal ions into the
gap forms abridge and provides nanocontact
between the electrodes, thus triggering a
quantum jump in electrical conductance.
Different metals have different anodic
deposition and stripping potentials. This
allows the sensorto achieve high specificity
by combining measurements such as redox
potentials, point-contact spectroscopy, and
electrochemical potential-modulated
conductance changes.
Results of preliminary tests on samples
containing elevated copper concentrations
showed that the deposition time needed to
bridge the nanoelectrode gap decreased
across samples as copper concentrations
increased. Detectionof copper at the EPAlimit
of 10"5 mol/L was achieved within 7 seconds,
while 1-nanomolar concentrations were
detected in 16 seconds. Similar results were
observed in lead detection tests.
This approach can be enhanced through use
of peptide-modified polymers that change
conductance between the nanoelectrodes in
the presence of heavy metal ions. When
integrated, these polymer nanojunction
sensors obtain more sensitive and real-time
measurement of heavy metals in ground or
surface water with higher accuracy.
Performance testing of laboratory-based
models of the nanocontact sensors involved
measurement of copper in drinking water
samples collected from different surface
water sources. Sensor data were compared
to information measured by conventional
laboratory techniques such as atomic
absorption spectrometry with a 90%
correlationbetweenthe data sets. Integrated
results from the nanocontact and polymer
nanojunction sensors were obtained in
approximately 96 and 97% less time,
respectively, than those gathered from
multiple laboratory procedures.
ASU researchers are developing a similar
field-portable sensor for use in monitoring
air quality and arsenic in ground water, as
well as other molecular- and nanojunction-
based chemical and biological sensors based
on carbon nanotube and polymer
technologies. Under a second STAR grant,
the group is investigating the fate, transport,
transformationandtoxicity of manufactured
nanomaterials of drinking water.
Contributed by Erica Forzani, Ph.D.,
Nongjian Tao, Ph.D., and Paul
Westerhoff, Ph.D., ASU (480-965-9058
or erica.forzani(a).asu.edu)
metal ions
Si3N4
nanoelectrode gap
Si3N4
Figure 2. Electronic beam
lithography provides the
nanoscale sensor with an
approximate 50-nm
nanoelectrode gap in which
stripping can be quantified.
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Bimetallic ZVI Technology Implementation Expands to Remediate VOC Hot Spots in Ground Water
The Naval Air Engineering Station
(NAES) in Lakehurst, NJ, is conducting
a series of bimetallic nanoparticle (BNP)
applications to treat ground water
containing chlorinated solvents. Initial
efforts to remediate the site involved a
pilot system for injection of oxygen and
propane to promote microbial degradation
of the contaminants. Unsuccessful pilot
results led to a 2001 treatability study and
2002 pilot test to evaluate BNP technology
as an alternative remedy. Based on
successful results, a full-scale application
was completed in 2003 to treat two
contaminant source areas at the facility. Six
rounds of post-injection ground-water
sampling demonstrated the technology's
effectiveness, and NAES now is planning
additional BNP work to be implemented
next year. The follow-on work will expand
the area of treatment while applying lessons
learned during earlier applications.
Full-scale BNP injections were conducted
in an area with two distinct contaminant
hotspots of a plume spanning approximately
two miles. The area contains unconsolidated
sediment extending approximately 75 feet
bgs and consisting of 86-94% sand mixed
with gravel and clay. Total organic carbon
levels range from 40 to 800 mg/kg.
Hydrologic evaluation of the area estimates
a ground-water velocity of 0.59 ft/day with
a hydraulic gradient of 0.002 ft/ft.
The plumes consist primarily of
tetrachloroethene (PCE), TCE, and 1,1,1-
trichloroethane (TCA) and degradation
products such as c/s-dichloroethene (cis-
DCE) and vinyl chloride. Contamination
extends 70 feet below the ground water
table, whichis located approximately 10 feet
Figure 3. Analysis of ground-water
samples collected from 11 monitoring
wells at the NAES indicated that total
VOC concentrations significantly
decreased over the five months following
BNP injections.
bgs, with greatest concentrations at a depth
of 45-60 feet below the watertable. The highest
total VOC concentrationin ground water prior
to treatment was approximately 900 ug/L.
The selected BNP slurry contained iron
particles averaging 50 nm in diameter and
coated with trace (0. l%by weight) palladium
that served as a catalyst for redox reactions.
The slurry was injected directly into the aquifer
across the treatment area over a period of 13
days using direct-push technology at 15
injection points. The injections were
conducted in a grid pattern for one portion of
theplume and inalinearpatternforthe second
portion in order to form a treatment wall
along the facility boundary. At each injection
point, twenty pounds of BNP were mixed
with 1,200 gallons of water and injected at a
rate yielding a BNP concentration of
approximately 2 g/L. A Geoprobe® distributed
the mixture over a 20-foot depth interval to
reach a total treatment depth of 70 feet bgs.
The first round of post-treatment sampling
of ground-water monitoring wells took
place the following week, and the final
round occurred nearly five months later.
Eleven monitoring wells were used to
monitor BNP effectiveness in the grid-
injected portion of the treatment area.
Additional wells located upgradient and
downgradient of the treatment area were
used to monitor effectiveness of the linear
injections and local conditions.
Contaminant concentrations decreased
throughout the monitoring period with
the exception of brief VOC elevations in
approximately 50% of the monitoring
wells one week after the injections were
completed. The temporary increases
likely were caused by BNP-induced VOC
desorption from soil particles to the
aqueous phase. Overall, TCE and DCE
concentrations decreased an average of
[continued on page 5]
250
200-
o 100 4
50 -
D Baseline (Pre Injection) - Oct 29 and 31, 2003
• Post Injection 1 - December 1 and 2, 2003
DPost Injection 2 - December 9 and 10, 2003
DPost Injection 3 - December 22 and 23, 2003
DPost Injection 4 - January 20 and 21, 2004
• Post Injection 5 - February 17 and 18, 2004
• Post Injection 6 - May 11 and 12, 2004
\
I
I
flta.
LK MW-1 MW-2 MW-3 MW-4 MW-5 MW-6 MW-7 MW-8 OW-2 RWI-1
Monitoring Well
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[continued from page 4]
79% and 83%, respectively, and the
average total VOC concentration decreased
74% (Figure 3).
All samples were analyzed in the laboratory
to determine VOC, chloride, iron, and
dissolved iron concentrations as well as
ground-water parameters such as
oxidation/reduction potential (ORP) and
pH. During the pilot test, ORP levels
reduced fromarange of+170 to+311 mV
prior to treatment to a range of -100 to
-400 mV after the injection process.
Significant reducing conditions were
observed for up to three months following
the injections.
Post-injection testing indicated a BNP
distribution of approximately 20-30 feetfrom
each injection point. BNP reactivity was
exhausted approximately nine months after
the injections, at which point an approximate
50% rebound in contaminant concentrations
was observed. The next round of injections
will employ a higher concentration of BNP
in order to expand the area of treatment and
more completely reduce contamination.
Remaining plume contamination will be
addressed through natural attenuation.
For the BNP work already completed,
NAES estimates a cost of $20,000 for
bench-scale testing, $60,000 for pilot
testing, and $250,000 for full-scale testing.
Costs forfull-scale implementation will vary
significantly, however, based on the size
and conditions of the treatment area and
the concentrations of VOCs to be treated.
Contributed by Mike Figura, NAES
Lakehurst (732-323-4857 or
michael.figura&navy.mil) andHarch
Gill, PARS Environmental, Inc. (609-
890-7277 or heill(a).narsenviro. com)
Microscale Metal Sorbents Approach Commercial Use
The U.S. Department of Energy (DOE)
Pacific Northwest National Laboratory
(PNNL) is working with private industry
to expand field application of sorbents for
removal and stabilization of specified
metals from contaminated liquid and
nonaqueous media. Known as "SAMMS"
(self-assembled monolayers on
mesoporous supports), the technology
employs mesoporous (20-200 A) materials
with a large enough pore size to allow
attachment of a monolayer and increased
access to pore binding sites. The material's
high surface area (approximately 1000m2/
g) also allows high densities of binding
sites. Five grams of SAMMS powder, for
instance, can provide a surface area
equivalent to a football field on which
binding molecules react. Bench- and field-
scale tests on mercury samples indicate
that the technology provides high metal
loadings, high metal affinities, and rapid
kinetics.
Both the monolayer and the mesoporous
support can be tailored for a specific
application. For example, the functional
group at the free end of the monolayer
can be designed to selectively bind targeted
ions or molecules while the pore size,
monolayer length, and density can be
adjusted to give the material specific
physical properties such as wettability and
diffusion. Based on the completed
laboratory and field testing of "Thiol-
SAMMS," which was designed specifically
for mercury removal, PNNL researchers
have compiled aqueous performance data
on key criteria such as maximum metal
loadings (Figure 4).
The initial large-scale field demonstration
of SAMMS was conducted during 2000 at
DOE's Mound Site to treat mercury-
contaminated oil in storage drums.
Analysis of the stabilized sludge solids and
oil following 24-hour contact with SAMMS
indicated that treatment successfully
reduced concentrations of mercury in the
oil from 4 mg/kg to below the RCRA
teachability limit of 0.2 mg/L.
Application lessons learned from the Mound
demonstration were employed the following
year to test the technology in stabilization of
more concentrated and co-contaminated
mercury in containerized vacuum pump oil
from Sandia National Laboratory. Testing
at Oak Ridge National Laboratory showed
that exposure to stabilized SAMMS fortwo
months allowed for successful absorption
of mercury in concentrations of 540 mg/kg
and stabilization of waste oil meeting RCRA
land disposal restrictions.
More recently, PNNL conducted bench-
scale treatability tests of Thiol-SAMMS
using metals-contaminated aqueous waste
from a pilot-scale waste glass melter
operation. Waste selected for this test
included soluble mercury concentrations
[continued on page 6]
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Technology News and Trends
welcomes readers' comments
and contributions. Address
correspondence to:
Ann Eleanor
Office of Superfund Remediation and
Technology Innovation
(5102G)
U.S. Environmental Protection Agency
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1200PennsylvaniaAve,NW
Washington, DC 20460
Phone:703-603-7199
Fax:703-603-9135
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Solid Waste and
Emergency Response
(5102G)
EPA 542-N-05-005
September 2005
Issue No. 20
United States
Environmental Protection Agency
National Service Center for Environmental Publications
P.O. Box 42419
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Permit No. G-35
[continued from page 5]
of 4.6 mg/L and high concentrations of
iodide ion, which strongly complexes
mercury. Test results indicated that
waste discharge limitof 0.15 mg/L.
Metal
Ag
Cd
Cu
Hg
Pb
Loading (mg/g)
440
97
40
635
122
Loading (mmol/g) I
4.08
0.86
0.63
3.17
0.59 I
SAMMS contact with pre-filtered waste PNNL anticipates that SAMMS soon will
solution removed approximately 99% of the be available in other engineered forms
mercury and achieved the RCRA mercury SUch as beads, membranes, and
membrane cartridges. More information
is available from PNNL at http://
samms.pnl.gov.
Contributed by Glen Fryxell, PNNL
(glen.fryxell&pnl. gov)
Figure 4. The
microscale structure
shows high rates of
maximum loading
for metals commonly
encountered at waste
Federal Agencies Partner in Upcoming Nanotechnology Workshop
On October 20-21,2005, nine federal agencies will convene a Nanotechnology for Hazardous Waste Site Remediation Technical
Workshop at the U.S. Department of Commerce in Washington, DC. The open workshop will serve as a:
> communication and scientific reporting forum on remediation research and technologies;
> stimulus for increased collaborations among researchers and government scientists; and
> forum for discussing research needs, barriers, and incentives for using new technologies to reduce environmental pollutants.
To register or obtain more information about the agenda, visit http://www.scgcorp.com/nanositeremed/index.asp.
EPA is publishing this newsletter as a means of disseminating useful information regarding innovative and alternative treatment techniques and
technologies. The Agency does not endorse specific technology vendors.
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