3
\
o
/A newsletter about soil, sediment, and ground-water characterization and remediation technologies
Issue 11
March 2004
AOP Treats Dioxane-Contaminated Ground Water
Contents
The San Gabriel Basin Water Quality
Authority is working with private industry
to examine options for removing 1,4-dioxane
in ground water undergoing chlorinated
solvent removal at two former industrial sites
in Southern California. Apump and treatment
system employing liquid-phase granular
activated carbon (LGAC) has operated at one
of the sites, in South El Monte, since 1995
to remove chlorinated solvents. The system
was found ineffective at removing 1,4-
dioxane, which was discovered in 1999 at
concentrations reaching 20 ug/L. Apilot-scale
advanced oxidation process (AOP) using ex-
situ injection of ozone and hydrogen peroxide
was implemented for one month in 2001 to
address the 1,4-dioxane.
The AOP is a continuous, in-line process
operating at feed water pressure with a flow
of 10-1,000 gpm. The 10-gpm AOP mobile
unit used during the pilot contains a solid-
state ozone generator producing ozone at a
pressure of 40-50 psig. The unit also houses
a hydrogen peroxide delivery system that uses
a continuous reactor to inject hydrogen
peroxide initially at a single point, followed
by ozone at multiple points along the flow
path. Earlier testing showed mat multiple
small-scale injections, rather than a single
large-scale event, increased the process
effectiveness and minimized byproduct
formation.
The continuous reactor initially contained 18
individual reactors, each with three separate
sections for injection, mixing, and chemical
reaction (Figure 1), and sampling ports at
the point of effluent. Depending on the rate
of flow, residence time within each of the
individual reactors was 3-10 seconds. Ozone
and hydrogen peroxide initially were applied
at rates of 9.4 ppm and 14.2 ppm,
respectively. Approximately 0.7 moles of
peroxide solution were injected into the
influent for each mole of ozone applied within
the reactor. Subsequent system optimization
reduced the ozone and hydrogen peroxide
application rates to 3.1 ppm and 6.9 ppm,
respectively, and reduced the number of
required reactors to 3.
Treatment resulted in a decrease of the 1,4-
dioxane concentration to a level below the
State of California drinking water standard
(3 ug/L) and a 98% decrease in most other
chlorinated solvents. Based on the pilot's
success, a full-scale AOP was constructed
in 2002 and has operated for the past year as
a continuous pre-treatment step. The system
comprises three ozone injectors with eight
static mixers operating at a capacity of 500
gpm.
Early monitoring results of the full-scale
operation demonstrate the same removal rates
for 1,4-dioxane and chlorinated solvents as
those observed during the pilot project. Data
indicate that addition of the AOP system is
increasing the life of the LGAC, which is
now replaced semi-annually rather than
quarterly. As a result of 1,4-dioxane removal,
effluent from the LGAC system now can be
reinjected into ground water approximately
1-2 miles upgradient of a nearby drinking
water well field to serve as a barrier.
Similar success was demonstrated in a pilot
AOP system operated in the City of Industry.
[continued on page 2]
AOP Treats Dioxane-
Contaminated Ground
Water
page 1
ETV Program Verifies
Performance of Ground-
Water Sampling Devices page 2
ESTCP Evaluates
Bimetallic Nanoscale
Particles in Treating
CVOCs page 3
NRMRL Evaluates
Microbial Responses
to Ground-Water
Remediation
Technologies page 5
On-line Resources
As a new feature of Technology
News and Trends, we will
highlight one of the many on-line
resources available through
CLU-IN, our primary information
network. In this issue we feature
EPA REACH IT (http^//
www.epareachit.org). where
environmental professionals can
search, view, download, and
print information about innovative
remediation and characterization
technologies. REACH IT
currently contains information on
435 technology vendors, 680
technologies, and 2,013
applications at Superfund sites.
Recycled/Recyclable
Printed with Soy/Car»la Ink or paper that
contains at least 50% recycled fiber
-------
continued from page 1]
At this location, 1,4-dioxane was
detected in extraction wells that feed
an air stripper used to remove
chlorinated solvents. Concentrations of
1,4-dioxane were found to decrease
consistently from 610 to 4 ppb during
AOP pre-treatment. Researchers believe that
a further reduction in 1,4-dioxane
concentrations would have been achieved
with higher ozone dosage. A full-scale
system with a 70-gpm capacity has been
installed at this site for use as a pre-
treatment step prior to air stripping.
03/02
I nj ecti on
Manifold
I nf I uent Water
Effluent Water
Due to the recent discovery of 1,4-dioxane
in ground water throughout California, the
Santa Clara Valley Water District
anticipates continued need for 1,4-dioxane
monitoring.
Contributed by Reid Bowman, Ph.D.,
Applied Process Technology, Inc. (805-
649-5796 or rbowman@aptwater.com)
and Tom Mohr, Santa Clara Valley
Water District (408-265-2607 or
tmohr@valley\vater. org)
Figure 1. AOP injections occurred in a
series of individual reactors, each of
which allowed mixing and reaction
with contaminated sround water.
ETV Program Verifies Performance of Ground-Water Sampling Devices
The EPA-sponsored Environmental
Technology Verification (ETV) program
has established several testing centers
over the past 10 years to verify new
technologies for a variety of
environmental applications. One of these
centers—the Advanced Monitoring
Systems Center (AMS)—recently tested
eight ground-water sampling devices:
six devices (including bladder pumps,
grab samplers, passive sampling devices,
and a down-well sampling module)
suitable for deployment in conventional,
2-inch diameter and larger wells and two
devices deployable in 1-inch or smaller
diameter wells installed by direct-push
methods.
As one of several third-party,
independent testing organizations within
AMS, Sandia National Laboratories
designed and conducted the tests in
cooperation with the technology
vendors. Tests were performed under
well-controlled conditions in a test facility
and under less experimental control at
contaminated ground-water sites.
Controlled testing was conducted at a 100-
foot standpipe at the U.S. Geological
Survey's Hydro logical Instrumentation
Facility at the NASA Stennis Space Center,
MS. The standpipe is housed in a former
Saturn V rocket hangar with multiple
access platforms along the length of the
standpipe. Large mixing tanks and a water
supply at the top of the pipe allow
contaminant-spiked solutions to be
prepared and dispersed into the standpipe.
Ground-water sampling devices were
deployed in the pipe from the top in the
same manner they would be deployed in
an onsite monitoring well. The 5-inch
diameter, stainless-steel standpipe was
equipped with multiple external access
ports along its length to allow collection
of co-located reference samples at the same
time that vendors collected samples from
inside the pipe.
Field testing of the conventional larger-scale
devices was conducted in a ground-water
monitoring well field at the NASA Stennis
site. Ground water in this region is
contaminated with a variety of volatile
organic compounds (VOCs)—predominately
chlorinated solvents—resulting from
former machine shop operations and
solvent disposal. VOC concentrations in
ground water at the test area ranged from
single digit parts per billion levels to tens
of parts per million.
Field testing for the smaller direct-push
well devices was conducted at Tyndall Air
Force Base, FL. Several areas of
contaminated ground water exist at the
site as a result of past disposal of solvents
used in aircraft maintenance. With its
existing network of 1 -inch diameter, direct-
push wells, Tyndall AFB is one of several
military installations involved in long-term
comparison of conventionally installed
wells and direct-push wells at
contaminated sites. VOC concentrations
in ground water at the test area ranged
from single digit parts per billion to
hundreds of parts per billion.
Performance of the following ground-
water sampling devices was verified in
cooperation with vendors:
[continued on page 3]
-------
Figure 2. Pooled test results for
conventional-well samplers were
compiled from six target VOCs at low
(20 \lg/L) and high (200 \lg/L)
concentrations and standpipe sampling
depths of 17, 35, 53, and 91 feet. Not
all samplers were deployed at all
sampling depths.
[continued from page 2]
> Multiprobe 100 (Burge Environmen-
tal, Inc.)
> SampleEase SP15T36 (Clean Envi-
ronmental Equipment)
> Micro-Flo 57400 (GeoLog, Inc.)
> Gore-Sorber Water Quality Monitor
(W.L. Gore and Associates)
> Kabis Sampler I/II (Sibak Industries)
> Well Wizard Dedicated Sampling Sys-
tem T120M/T1250 (QED Environ-
mental Systems, Inc.)
> Mechanical Bladder Pump MB470
(Geoprobe Systems, Inc.), and
> Pneumatic Bladder Pump GW1400
(Geoprobe Systems, Inc.).
Sampler Type
Multiprobe 100
SampleEase
Micro-Flo
Gore-Sorber
Kabis Sampler
Well Wizard
Precision
(Percent Relative Standard Deviation)
Median (Range)
Technology
9.4 (3.0-21.1)
11.7 (5.1 -24.2)
8.5 (2.7-26.7)
14 (2-28)
10.7 (2.9-25.8)
7.7 (3.9-19.7)
Reference
8.6 (2.0-17.4)
10.7 (4.1 -15.2)
4.7 (1.6-30.8)
N/A [see report]
8.7 (4.1 -17.6)
8.2 (1.1 -30.7)
Relative Accuracy*
(Percent Difference)
Median (Range)
-5 (-30-15)
-5 (-16-31)
-1 (-21 -27)
N/A [see report]
-3 (-39-18)
1 (-17-20)
* relative to co-located and simultaneous standpipe reference samples
Each device was used to collect 100 or more
standpipe and ground-water samples and all
vendor samples were matched with
reference samples. Performance was
determined for sampler precision,
comparability with a reference, versatility,
and logistical requirements. Typical precision
and relative accuracy performance data for
standpipe VOCs are summarized in Figures
2 and 3.
Sampler Type
Mechanical Bladder Pump
Pneumatic Bladder Pump
Precision
(Percent Relative Standard Deviation)
Median (Range)
Technology
1.2 (0.2-3.4)
1.3 (0.3-2.8)
Reference
1.4 (0.0-2.5)
1.6 (0.4-2.6)
Relative Accuracy*
(Percent Difference)
Median (Range)
-2.5 (-5.0- 0.3)
-2.3 (-5.6 - 0.9)
* relative to co-located and simultaneous standpipe reference samples
In general, test results revealed that all
tested sampling devices are suitable for
use in various ground-water sampling
applications. The published
performance verification data for each
device can be used to optimize the
choice of a sampler in a particular field
application. A complete performance
report on each of these ground-water
sampling devices is available on the
ETV website (http://www.epa.gov/etv).
Contributed by Wayne Einfeld,
Sandia National Laboratories (505-
845-8314 or w ein fel&sandia. sov)
Figure 3. Pooled test results for
narrow-bore well samplers were
compiled from four target VOCs at
intermediate (-80 /Jg/L) concentra-
tions and standpipe sampling at
depths of 17 and 35 feet.
ESTOP Evaluates Bimetallic Nanoscale Particles in Treating CVOCs
Under the Environmental Security
Technology Certification Program
(ESTCP), the U.S. Department of
Defense (DOD) is evaluating the use of
bimetallic nanoscale iron (BNI) particles
in establishing a permeable, in-situ,
reactive zone for treating chlorinated volatile
organic compounds (CVOCs) in ground
water. When compared to conventional
iron-based permeable reactive barriers
employing granularparticles, nanoscale (less
than a micron in size) metallic iron provides
more available surface area per unit of
iron mass. Preliminary results of the
ESTCP study indicate that the increased
surface area allows higher levels of
[continued on page 4]
-------
[continued from page 3] conversion of contaminants into non-toxic
reactivity with
gas.
contaminants, while
generating lower iron mass loadings. DOD Using BNI produced through two types of
anticipates that the use of nanoscale colloid manufacturing techniques,
particles will enable iron to be injected laboratory studies were conducted in soil
beneath ground-surface structures, columns packed with soil and treated with
where surface access is otherwise limited ground-water samples taken from
a site at
by existing land uses, or at depths at which Vandenberg Air Force Base, CA, which
trenching is impractical, with minimal serves as the primary pilot location for this
ground surface disruption. project. Samples were collected several
hundred yards from a missile launch pad
The use of BNI colloids for in-situ , • , , i, . • 1 1 ,1
drainage channel where trichloroethene
remediationbuilds on the use of nanoscale ^^T-,, ,- , • ,
11 -j i u- uu u (TCE) was found in ground water at a
ironcolloidsalone,whichhavebeenused concentration of 2 5 /L The TCE
by others in both bench- and field-scale , , .. . . , ~ ,. ,, .,
degradation product as- 1 .2-dichloroethene
applications. During this project, analytical (DCE) ^ wag identffied but at lower
results showed that the addition of an
concentrations.
incomplete coating (0.03% w/w) of
palladium as a hydrogenation catalyst to The "aqueous precipitation" technique used
the surface of nanoscale iron particles to manufacture nanoscale iron particles
increased the CVOC dechlorination rate involves reduction of a solution of ferric
from a kinetic value of 0.002 L/mVg to chloride using sodium boro hydride. In
values of IL/mVg or more. Data indicated contrast, the "ball milling" technique
that the increased surface area provided involves reduction of larger, typically
by nanoscale iron, combined with the micron-size, iron powder granules to
increased reaction rate caused by the nanoscale size through an attrition process
addition of hydrogenation catalyst, using a suitably sized ball mill. Over three
achieved a 100-150% higher treatment years, this project supported enhancements
rate than those estimated to be achieved to the ball milling process that have lowered
by granular iron filings. The addition of the cost of manufacturing nanoscale iron
palladium also enabled more complete to $5/lb (Figure 4).
10000 -
•4 f)f\r\
_- 1000
§
:^~ -i f\f} —
7/5 100
1
o
Q 10 -
\
x
V
^""•*>>(^
^^^^
^*">v
X
111111
1
1997 1998 1999 2000 2001 2002 2003 2004
Years
— Precipitated — Ball Milled
To date, laboratory testing has resulted in
the creation of a "library" of kinetic
treatment rates indexed by the types of
nanoscale iron being tested. The kinetic
rate constants normalized for the surface
area of iron have ranged from 0.05 L/m2/
g to 0.4 L/m2/g. Colloids ranging in size
from 200 to thousands of nanometers
were tested in the laboratory to determine
the optimal size for field application.
Results demonstrated that colloids in the
range of 200-600 nanometers achieved
optimal mobility and a sufficient reactivity
rate for in-situ CVOC dechlorination.
Colloids of smaller size were subject to
adsorptive interfacial forces in the geologic
matrix, while larger ones were adversely
affected by gravitational settling.
This project has resulted in a cost-effective
BNI production process mat can be up-
scaled to yield nanoscale iron in large
quantities (several tons) for full-scale
remediation. As it continues, this project
will focus on: (1) understanding and
manipulating technical factors that
improve the reactive life of BNI once it is
deployed in-situ; and (2) demonstrating
BNI applicability for remediation of
CVOCs present as dense, nonaqueous
phase liquid (DNAPL) in laboratory soil
columns. Updated information on this
ongoing ESTCP project is available at
http://www.estcp.org.
Contributed by David Liles, ARCADIS
(919-544-4535 or dliles&arcadis-
us.com) and Andrea Leeson DOD/
SERDP (703-696-2118 or
Andrea.Leeson&osd.mil)
Figure 4: Field application of
nanoscale iron particles for
remediation of contaminated ground
water is no longer significantly
limited by colloid manufacturing
costs.
I 1
-------
NRMRL Evaluates Microbial Responses to Ground-Water Remediation Technologies
The U.S. EPA National Risk
Management Research Laboratory
(NRMRL) recently completed
independent evaluation of the microbial
responses to technology demonstrations
that were conducted over the past several
years at Cape Canaveral Air Station, FL.
The Interagency DNAPL Consortium had
conducted side-by-side field
demonstrations of three technologies for
treating trichloroethene existing as
DNAPL: permanganate-based, in-situ,
chemical oxidation (ISCO), six-phase
heating (SPH), and steam injection (SI).
[Performance summaries are available in
the March 2003 Technology News and
Trends and July 2001 Ground Water
Currents at http://www.clu-in.org]. The
recent NRMRL evaluation was
conducted in part to address concerns
that aggressive source control
technologies such as those demonstrated
at Cape Canaveral might sterilize the
subsurface, thus hampering the use of
natural or enhanced bioattenuation
processes as remedial finishing steps.
Aggressive technologies typically
remediate a substantial portion of DNAPL
but do not achieve regulatory clean-up
levels. Results of the study indicate that
sterilization did not occur. Biomass levels
following application of all three
technologies returned to near pre-
treatment levels.
NRMRL's study focused on the analysis
of phospholipid ester-linked fatty acids
(PLFA) profiles, which provide
information on the phy logenic identity and
physiological status of microbes.
Individual fatty acids are known to differ
in chemical composition that depends on
microbial type and environmental
conditions. These differences allow fatty
acids to be used as biomarkers providing
a quantitative insight into three primary
attributes of microbial communities: viable
biomass, community structure, and
metabolic activity.
During the three-year NRMRL evaluation,
PLFA distribution and content were
determined from 266 core samples
extracted aseptically at depths of 6-44 feet.
Samples were collected at a site control
with no DNAPL contamination and in the
areas where each of the three
demonstrations occurred (Figure 5).
Comprehensive spatial and temporal
screening data suggested that the
technology applications did not significantly
alter the site's microbial community
structure. PLFA distribution at the site
control suggested that the microbial
community structures were atypical. In
particular, the biomass gradient did not
decrease with increasing depth. The high
level of biomass variation identified at each
depth, however, was consistent with the
extensive heterogeneity of biota expected
in subsurface environments. Analysis of
fatty acid structural groups indicated that
short saturates constituted the largest
group and that the number of long saturates
was significantly higher than usual. These
findings contrasted with other studies
indicating that monosaturated PLFAusually
are the most abundant in subsurface
conditions, while long saturates constitute
a fewer percent of the total fatty acids.
PLFA distribution for each of the three
demonstration areas also indicated a high
variation in biomass at each sampling event
and depth. ISCO was the only technology
found to stimulate microbial abundance; a
significant initial increase in biomass was
observed following completion of the ISCO
demonstration. This behavior is consistent
with findings from other permanganate-
based chemical oxidation applications.
Biomass and the proportion of
monounsaturates returned to normal levels
shortly after chemical injections ceased.
In general, no significant change in the
microbial community composition was
observed in the SPH or SI treatment areas
at Cape Canaveral. Microbial communities
recovered to near initial conditions by the
second sampling event performed for both
the SPH and SI demonstrations.
Limiting factors for this evaluation may
include the selection of fatty acid
structural groups that may have been
insufficiently sensitive to subtle
differences in microbial populations, or
the use of samples with very low biomass
and corresponding patterns of PFLA.
Although the PLFA tests suggest that the
indigenous microbial population recovered
after treatments, further investigations are
required to demonstrate conclusively that
[continued on page 6]
Contact Us
Technology News and Trends
is on the NET!
View, download, subscribe, and
unsubscribe at:
http://www.epa.gov/tio
http://clu-in.org
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
Ariel Rios Building
1200 Pennsylvania Ave, NW
Washington, DC 20460
Phone:703-603-7199
Fax:703-603-9135
-------
Technology
News and Trends
Solid Waste and
Emergency Response
(5102G)
EPA 542-N-04-002
March 2004
Issue No. 11
United States
Environmental Protection Agency
National Service Center for Environmental Publications
P.O. Box 42419
Cincinnati, OH 45242
First Class Mail
Postage and Fees Paid
EPA
Permit No. G-35
Official Business
Penalty for Private Use $300
[continued from page 5]
the population can be used as a finishing
step. Details on the general approach used
for sampling and analysis during this
study will be available in a 2004
environmental research brief available at
http://www.epa.gov/ORD/NRMRL/Pubs/
index.html.
Contributed by Ann Azadpour-Keeley,
NRMRL (580-436-8890 or
keeley.ann&gpa.gov)
Figure 5. A total of 266
core samples were
analysis in the three
demonstration areas and
from site control locations
at Cape Canaveral Air
Station.
MBC-019
MBf120 ,'
MB-30S
MBC-009i
TB&//vtsti
mto»f ,-'SS§/
f / £LMB-10a l t
MB-30SMB-20S/ •
;v;
,MBC-01Q
A Test Core
Sw-P/iase Heaf/ng (SPHj: MS 01 - MS 05
InStu Chemical Oxidation (/SCO): MB 06 - MB 10
Steam Injection (SI): MB 16-MB 20
Control Core
Plot Controls: MBC-01 - MBC-14 &MB-16- MB-20
Site Controls: A-E. -date
Core Sampling Code:
MB-210
A / l\
Test Cote / Core Location
2"°'Post-demonstration
Monitoring Event
Test Plot Boundaries
0 25 50
I i i
FEET
July 2003
.,
Xchemical^:
Oxidation
°
EPA is publishing this newsletter as a means of disseminating useful information regarding innovative and alternative treatment techniques and
6 technologies. The Agency does not endorse specific technology vendors.
------- |