Fundamental study of the delivery of nanoiron to DNAPL source zones in naturally heterogeneous
field systems
Funding
Agency
Department of Defense Strategic Environmental Research and Development Program
(SERDP)
April
2006-March 2009
Collaborators
Tissa Illangasekare (
Publications
Navid Saleh,
Hye-Jin Kim, Krzysztof Matyjaszewski,
Robert D. Tilton, and Gregory V. Lowry. Ionic Strength and
Composition affect the mobility of surface-modified NZVI in water-saturated
sand columns. Environ. Sci. Technol.
(submitted).
Phenrat, T., Saleh, N., Sirk, K., Kim, H., Matyjaszewski, K., Titlton, R.,
Lowry, G.V. Stabilization of Aqueous Nanoscale
Zerovalent Iron Dispersions by Anionic Polyelectrolytes: Adsorbed anionic polyelectrolyte layer
properties and their effect on aggregation and sedimentation. J Nanoparticle Res.
(submitted).
Liu, Y., Phenrat, T., Lowry, G. V. Effect of TCE concentration and dissolved groundwater solutes on
NZVI-promoted TCE dechlorination and H2
evolution. Environ. Sci. Technol. (in press).
Phenrat, T., Saleh, N.,
Sirk, K., Tilton, R., Lowry, G. V. (2007) Aggregation and Sedimentation of
Aqueous Nanoiron Dispersions. Environ. Sci. Technol.,
41 (1) 284-290.
Saleh, N., Sirk, K., Liu,
Y., Phenrat, T., Dufour,
B., Matyjaszewski, K., Tilton, R., Lowry, G. V. (2007) “Surface Modifications Enhance Nanoiron Transport and DNAPL Targeting in Saturated Porous
Media.” Environ.
Liu, Y., Lowry, G.V. (2006) “Effect of Particle Age (Fe0 content) and
Solution pH on NZVI Reactivity: H2 Evolution and TCE Dechlorination”. Environ. Sci. Technol.,
40 (19) 6085-6090.
Abstract
Chlorinated
solvent DNAPL is a consistent long-term source of groundwater
contamination. Remediation is costly and
poses significant technical challenges.
Lifecycle treatment costs are estimated to exceed $2 billion for ~3000
contaminated DoD sites (Stroo et al., 2003).
Nanoiron is a promising in situ remedial agent
that has been evaluated at 5 DoD
sites to remediate chlorinated solvent plumes, and may also be effective for
treating chlorinated solvent DNAPL sources.
The effectiveness of nanoiron treatment relies
on the ability to place and retain the nanoiron near
the DNAPL source area without negatively affecting the DNAPL architecture. The dominant physical and chemical processes
controlling the migration and distribution of nanoiron
in the subsurface are poorly understood, however, making it difficult to ensure
that nanoiron will be delivered where it is needed
and to minimize the potential to worsen the problem through unfavorable changes
in DNAPL architecture.
The
research objective is to obtain a fundamental understanding of the physical and
geochemical processes governing the migration and distribution of nanoiron in DNAPL contaminated zones of a naturally
heterogeneous subsurface where the free phase is entrapped in a complex
architecture. The physicochemical principles controlling colloid transport will
be exploited to develop nanoiron with surface
properties that enables transport, provides DNAPL targeting, and mitigates the
technical risks of using nanoiron for DNAPL source
treatment.
Delivering nanoiron to subsurface
DNAPL requires that the nanoiron be transported
through water saturated porous media without being filtered out by aquifer
media, and that the nanoiron properties change in the
vicinity of the DNAPL such that the nanoiron remains
there. Subsurface heterogeneity and
geochemistry will impact nanoiron delivery. Controlled investigations in small 1-D and
2-D laboratory test systems and large intermediate scale test tanks will be
used to 1) determine the nanoiron and aquifer
geophysical-chemical properties controlling nanoiron
migration, 2) identify the nanoiron surface properties
and hydrodynamic conditions needed for DNAPL targeting, 3) evaluate coatings
that impart these surface properties while retaining high nanoiron
reactivity, 4) determine how physical heterogeneity affects the ability to
contact the iron and the DNAPL, and 5) explore up-scaling methods that may be
used with available colloid transport and advection-dispersion models to
predict the migration and targeting of nanoiron
particles in heterogeneous field systems.
The proposed study will determine conditions where nanoiron may provide a rapid cost-effective method to
diminish the mass and strength of a DNAPL source, and provide significant cost
savings compared to other technologies.
Specific benefits include 1) effective control of nanoiron
delivery to the DNAPL source and the ability to retain it there, 2) the ability
to select an injection method and rate, and nanoiron
surface properties that can be optimized for site-specific physical
characteristics and geochemistry, and 3) a rapid assessment tool to predict the
effectiveness of nanoiron for DNAPL source reduction
based on site specific parameters. The
fundamental understanding of these processes will allow for optimizing the
targeted delivery of nanoiron or other nanoparticulate remediation agents.
Greg Lowry Home | Dept. Civil & Env.