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Valentine A. Nzengung, Professor
University of Georgia
Department of Geology
Room 132, GGS Building
Athens, GA 30602
Phone: 706-542-2699
Fax: 706-542-2425
e-mail: vnzengun@uga.edu
Education:
Georgia Institute of Technology,
Atlanta, GA
Ph.D. Environmental
Geochemistry, 1993
MS. Environmental Engineering, 1993
Georgia State University, Atlanta, GA
B.Sc. Geology, Cum Laude, 1988
Research
Interest
My research focuses
on the development and evaluation of innovative technologies for the
cleanup of water, sediment, and soils. Particular emphasis is placed
on sorption and degradation of contaminants and immobilization of
metals. Specifically, my ongoing research focuses on the following
five technologies:
·
Phytoremediation
Technologies: Cleanup of soils, sediment, water and
air using green plants and root zone associated mechanisms.
·
Microbial Mats
Treatment System: Treatment of contaminated waters using green
photosynthesizing microbial mats dominated by cyanobacteria.
·
Abiotic
transformation of organic contaminants: Chemical
treatment of contaminated soils and water. Emphasis is placed on the
applications of activated bulk reductants in remediation of oxidized
compounds, including the immobilization of metals.
·
Preparation and
characterization of surfactant modified (organo-modified clays or
Clay nanocomposites) as cost-effective sorbents/filtration media for
perchlorate and organic contaminants.
·
In-situ
bioremediation of soils and groundwater: Biostimulation and enhancement of
contaminants degradation in soil and groundwater using innovative
techniques to deliver carbon and electron donors to the subsurface.
This approach avoids expensive dig-and-treat of contaminated source
area soils in the vadose zone.
Phytoremediation Technologies
Phytoremediation is the use of green plants (both aquatic and terrestrial) and the
root zone associated microorganisms to cleanup hazardous waste sites.
Phytoremediation involves a multitude of processes, thus the name
phytoremediation technologies. A rigorous design of phytoremediation
identifies and enhances the most applicable processes for the field
site of interest. Phytoremediation is effective in treating livestock
and poultry wastes, munitions constituents (e.g., perchlorates and
nitroaromatics), organic contaminants, and metal contaminated
hazardous waste sites. Compared to other remediation approaches,
phytoremediation is more acceptable to the public and regulatory
agencies because the ecosystem health is significantly improved
during cleanup of the contaminants of concern. The trees also remove
greenhouse gases from the atmosphere to produce biomass, which could
be utilized as raw material for biofuels production.
My
research group has screened many species of terrestrial and aquatic
plants for the purpose of identifying the most effective species for
phytoremediation of the different groups of contaminants. The data
generated from our laboratory studies, so far, has been valuable in
the development of better environmental fate models by regulatory
agencies, design, and field application of phytoremediation
technologies. We have coupled laboratory and field data from our
analysis of plants used in a demonstration project at the Carswell
Air Force base in Fort Worth, Texas, to provide a better
understanding of phytoremediation processes and pathways for
chlorinated organic solvents. Also, at a Naval Facility in Florida,
we have successfully coupled phyto-processes and natural attenuation
to accelerate the cleanup of a shallow chlorinated solvent plume
upwelling into a wetland and recreational lake. Our research also
involves engineered phytoremediation; an innovative approach for
biostimulation and enhancement of rapid rhizodegradation of
degradable contaminants such as nitrate, perchlorate, explosives
constituents, chlorinated solvents, pesticides, and petrochemicals.
Rhizodegradation enhancement significantly reduces the cleanup time
and minimizes uptake and accumulation of degradable contaminants in
plant tissues. Thus, if rhizodegradation can be successfully
achieved, there is no need to dispose of the plant matter as
hazardous waste when the soils and water cleanup goals have been
achieved.
Microbial Mats Treatment System
Microbial mats are
naturally occurring stratified microbial communities, composed of a
complex consortia of bacteria dominated by photoautrophic
cyanobacteria (also referred to blue-green algae). Mats generally
include anoxygenic photoautrotrophs (purple bacteria) as well as
sulfur-reducing microorganisms. They are tightly annealed together
within a negatively charged polymeric matrix of gel. The 3.5
billion-year survival of mats testifies to their successful capacity
in altering hostile environments through cellular and
community-mediated activities.
“Constructed”
microbial mats grown using a standard technique that is very
inexpensive and can be accomplished with minimal training is used at
the bench and field scale to treat complex waste streams and produce
biomass. The mats are very effective for sequestering or
precipitating metals/radionuclides by surface absorption or by
altering the surrounding chemical environment, thus they
bioconcentrate the metals/radionuclides in a small volume (<5% of
wet mass). The microbial mats are used to mineralize organic and
inorganic contaminants, including pesticides, munitions constituents
(i.e., perchlorate and explosive compounds), petrochemicals, and
chlorinated solvents. Because microbial mats use greenhouse gases to
produce biomass and are among the fastest growing photoautotrophs,
they show great promise in the production of biomass for bioenergy.
My research group continues to develop new applications for microbial
mats in bioenergy, bioremediation, and sequestration of greenhouse
gases.
Contaminated
soils are often the long-term sources of contaminants leached into
surface and ground waters. Most soils will normally contain natural
bacteria capable of degrading the contaminants of concern. As a
result, the persistence of degradable contaminants in soils and
groundwater is commonly caused by the limited supply of nutrients and
suitable environmental conditions to support the growth of
microorganisms capable of degrading the contaminants of concern.
Building on results of multiple bench scale tests, we have
demonstrated at field sites the efficacy of in-situ bioremediation by
applying suitable carbon and electron donors at the soil surface and
progressively mobilizing into the groundwater below. The amendments
mixed in with the surface soils create suitable conditions for growth
of significantly high numbers of indigenous microorganisms capable of
degrading the contaminants of concern. The successful infiltration of
selected suitable carbon and electron donors through the vadose zone
into the site groundwater apparently creates favorable environmental
conditions for the growth of very high numbers of the microorganism
capable of degrading the contaminants. Even more important, the
latter approach achieves a larger foot print of bioremediation than
injection systems. This Surface Application and Mobilization of
Nutrient Amendments process has been successfully applied at the
field scale to cleanup perchlorate, munitions, pesticides, and
petrochemicals in vadose zone soils and groundwater. Since there is
no dig-and-treat involved, the technology costs are an order of
magnitude less than for competing technologies, such as windrow
composting, soil vapor extraction system, soil washing,
pump-and-treat, thermal treatment.
My
research group has been studying the application of
oxidation-reduction reactions of iron and other redox sensitive
metals in soils and sediments in remediation of contaminated soils,
sediment and waters. Our research has focused on the role of ferric
(Fe(III)) and ferrous (Fe(II) iron because Fe(III) is the fourth most
abundant element in earth materials and the most important electron
acceptor following the onset of anoxic conditions in groundwater,
soils and sediment. Completed and ongoing research involves the
enhanced degradation of oxidized organic contaminants (e.g.,
chlorinated aliphatics and aromatics, explosives, PCBs, DDT, etc.)
using the free radicals generated during the decomposition of bulk
reductants under suitable environmental conditions. Aquifer material
and soils are chemically treated with bulk reductants (e.g.,
dithionite) to create reducing conditions. Specific interest is
placed on the reaction kinetics, identification of degradation
products and determination of mass balance. The advantages offered by
this innovative approach are: (1) in-situ redox manipulation using
dithionite enhances reductive dechlorination of chlorinated organics
and immobilization of metals, (2) rapid degradation of explosive
compounds in soils and groundwater at Military Ranges and other
Defense facilities, (3) the system can be easily optimized and
regenerated, (4) no toxic end-products are generated, and (5)
remediation costs are less than those of most conventional abiotic
and biotic techniques.
Preparation and
characterization of surfactant modified clays (clay nanocomposites)
Building
on my previous research on sorption and degradation of organic
pollutants, we are developing unique formulations of surfactant
modified clay (SMC) for sorption and treatment of waste water. The
SMC (also called organo-modified clays or organoclays) are effective
sorbents for filtration of nitrate, perchlorate, metals and organic
contaminants from water. My research also involves studying the
effects of organic cosolvents, solute properties and organoclay
structure on the mechanism of sorption of hydrophobic organic
chemicals and development of nonselective organoclays. Since the raw
clays are widely available and cheap, SMC can be utilized
commercially as low cost use-and-toss sorbents.
Invited Book Chapters
·
Nzengung,
V. A., Hans F. Stroo,
Tony M. Lieberman. 2007. Emerging Technologies for Perchlorate
Bioremediation. Publisher: Environmental Security
and Technology Certification Program (ESTCP ) 2007 (In Press). · Nzengung,
V. A.
2006. “Using Hydroponic Bioreactors to Assess Phytoremediation
Potential of Perchlorate,” Phytoremediation:
Methods and Reviews, Neil
Willey Eds. (In Press)
· Nzengung,
V. A.,
O’Niell, W., McCutcheon, S.C., and Wolfe, N.L. 2003. “Chapter
16: Sequestration and Transformation of Water Soluble Halogenated
Organic Compounds Using Aquatic Plants, Algae, and Microbial Mats” Phytoremediation:
Transformation and Control of Contaminants , Steven C. McCutcheon and Jerald L. Schnoor Eds. John Wiley &
Sons, Hoboken, NJ. p.499-528.
· Nzengung, V. A.,
and McCutcheon, S.C. 2003. “Chapter 29: Phytoremediation of
Perchlorate,” Phytoremediation: Transformation and Control of
Contaminants, Steven C. McCutcheon and Jerald L. Schnoor Eds.
John Wiley & Sons, Hoboken, NJ. p.863-885.
· Nzengung, V. A.,
Wang C. 2000. “Chapter 21: Influences on Phytoremediation of
Perchlorate Contaminated Water,” American Chemical Society
(ACS) Special Symposium Series: Perchlorate in the Environment,
Editor: Urbansky. Kluwer Academic/Plenum Publishers, New York. p.219
- 229.
Journal Publications
·
Dawit D. Yifru and Nzengung, V. A. 2006. Uptake of Perchlorate by Vegetation
Growing at Field Sites in Arid and Subhumid Climates. Remediation Autumn 2007. p. 53-68. · Dawit D. Yifru and Valentine A. Nzengung. “Uptake of N-Nitrosodimethylamine
(NDMA) from Water by Phreatophytes in the Absence and Presence of
Perchlorate as a Co-contaminant.” Environmental Science &
Technology, Vol. 40, p.7374-7380.
· Dawit D. Yifru and Valentine A. Nzengung. “Use of Dissolved Organic Carbon to
Enhance Rhizodegradation and Minimize Uptake of Perchlorate (ClO 4-)
(Submitted 2006).
· Dawit D. Yifru and Valentine A. Nzengung. “Use of Dissolved Organic Carbon to
Biostimulate Rapid Rhizodegradation of Perchlorate in Soil
(Submitted 2006)
· Nzengung, V.A., Penning, H., and O’Niell, W. “Mechanistic Changes During
Phytoremediation of Perchlorate Under Different Root Zone
Conditions,” International Journal of Phytoremediation:
Vol. 6, No. 1, pp. 63-83. 2004.
· Nzengung, V. A.
and Jeffers, P.M. ‘Sequestration, Phytoreduction, and
Phytooxidation of Halogenated Organic Chemicals by Aquatic and
Terrestrial Plants,” International Journal of Phytoremediation:
Vol. 3, No. 1, pp. 13-40. 2001.
· Nzengung, V. A.,
Castillo, R.M., Gates, W.P., Mills, G.L. “Abiotic Transformation
of Perchloroethylene in Homogeneous Dithionite Solution and In
Suspensions of Dithionite-Treated Clay Minerals,” Environmental Science & Technology, Vol. 35, No. 11, p.2244-2251. 2001.
· Garrison, A. W., Nzengung, V. A., Avants, J. K., Ellington, J. J., Wolfe, N.
Lee. “Phytodegradation of p,p’-DDT and Enantiomers of
o,p’-DDT,” Environmental Science & Technology, Vol.
34, p.1663–1670. 2000.
· O’Niell, W., Nzengung, V. A., Noakes, J., Bender, J., Phillips, P.
“Biosorption and Biodegradation of Tetrachloroethylene and
Trichloroethylene Using Mixed-Species Microbial Mats,” Journal
of Hazardous Substance Research. Vol. 2. 2000. p. 2-1 to 2-16. (PDF)
· Nzengung, V. A.,
Wang, C., Harvey, G. “Plant-Mediated Transformation of
Perchlorate into Chloride,” Environmental Science &
Technology, Vol. 33, p.1470-1478. 1999.
· Nzengung, V. A.,
Wolfe, L.N., Rennels, D., McCutcheon, S.C. “Use of Aquatic Plants
and Algae for Decontamination of Waters Polluted with Chlorinated
Alkanes,” International Journal of Phytoremediation, Vol.
1, No. 3, p.203-226. 1999.
· Jeffers, P.M.,
Wolfe, N.L., Nzengung, V. A. “Green Plants: A Terrestrial
Sink for Atmospheric CH 3Br,” Geophysical Research
Letters, Vol. 25, No. 1, p.43-46. 1998.
· Nzengung, V. A., Nkedi-Kizza, P., Voudrias, E. A. “Organic Cosolvent Effects
on Sorption Kinetics of Hydrophobic Organic Chemicals by
Organoclays,” Environmental Science & Technology, Vol. 31, No. 5, p.1470-1475. 1997.
· Nzengung, V. A.,
Voudrias, E.A., Nkedi-Kizza, P., Wampler, J.M., Weaver, C.E.
“Organic Cosolvent Effects on Sorption Equilibrium of Hydrophobic
Organic Chemicals by Organoclays,” Environmental Science &
Technology, Vol. 30, No. 1, p.89-96. 1996.
· Voudrias, E.A, Nzengung, V. A., and Li, C. “Removal of Light Nonaqueous
Phase Liquids (LNAPLs) by Flushing,” Journal of Waste
Management, Vol. 14, No.2, p.115-126. 1994.
Other Publications
Conference Proceedings and Other Invited Papers
·
EPA
542-R-05-001.
January 2005. www.rtdf.org: “Evaluation of Phytoremediation for
Management of Chlorinated Solvents in Soil and Groundwater”
prepared by the USEPA's Remediation Technologies Development Forum:
Phytoremediation of Organics Action Team, Chlorinated Solvents
Workgroup. Authored by USEPA Remediation Technologies Development
Forum (RTDF): Phytoremediation of Chlorinated Solvents Subgroup
Members. · Nzengung, V.A
and O'Niell, W. “In-Situ Bioremediation of Explosives and
Perchlorate in Vadose Zone Source Areas” 2005
NGWA Conference on MTBE and Perchlorate: Assessment, Remediation,
and Public Policy. May 26 – 27, 2005. Proceedings
of the 2005 National Ground Water Association Press. Copyright 2005.
ISBN #1-56034-120-3. p. 307-319 Learn More
· *Dawit
D. Yifru and Nzengung, V.A. “Enhancement of Microbial
Degradation of Perchlorate (ClO 4-) in the
Rhizosphere,” Paper A-23, in: B.C. Alleman and M.E.
Kelley (Conference Chairs), In Situ and On-Site
Bioremediation—2005. Proceedings of the Eighth International
In Situ and On-Site Bioremediation Symposium (Baltimore, Maryland;
June 6–9, 2005). ISBN 1-57477-152-3, published by Battelle Press,
Columbus, OH, www.battelle.org/bookstore.
· *Dawit D. Yifru and Nzengung, V.A. “Biostimulation and Enhancement of
Rhizodegradation of Perchlorate during Phytoremediation,” 2005
NGWA Conference on MTBE and Perchlorate: Assessment, Remediation,
and Public Policy. May 26 – 27, 2005. Proceedings
of the 2005 National Ground Water Association Press. Copyright 2005.
ISBN #1-56034-120-3. p. 249-258. Learn More
· *Lina Wayo and Nzengung, V.A. “Biodegradation of Polycyclic Aromatic
Hydrocarbons in Compost Extract Treated Soils,” Paper
F-27, in: B.C. Alleman and M.E.
Kelley (Conference Chairs), In Situ
and On-Site Bioremediation—2005.
Proceedings of the Eighth International In Situ and On-Site
Bioremediation Symposium (Baltimore, Maryland; June 6–9, 2005).
ISBN 1-57477-152-3, published by Battelle Press, Columbus, OH, www.battelle.org/bookstore.
· *O'Niell, W.L. and Nzengung, V.A. “In-Situ Bioremediation and
Phytoremediation of Contaminated Soils and Water: Three Case
Studies,” US Baltic International Symposium - Advances in Marine
Environmental Research, Monitoring and Technologies, June 15-17,
2004, Klaipeda, Lithuania. 6p.
· Sparling, D.W.,
Harvey, G., and Nzengung, V.A. “Interaction Between
Perchlorate and Iodine in the Metamorphosis of Hyla versicolor”
Multiple Stressor Effects in Relation to Declining Amphibian
Populations. ASTM STP 1443. Editors: G. Linder,
S. Krest, E. Little, and D.W. Sparling, American Society for Testing
and materials, West Conshohocken, PA, 2002.
· *O'Niell, W. and Nzengung, V.A. “Feasibility of In Situ Bioremediation of
Perchlorate Contaminated Soils,” Paper C-09, in:
V.S. Magar and M.E. Kelley (Eds.), In Situ and On-Site
Bioremediation—2003. Proceedings of the Seventh International
In Situ and On-Site Bioremediation Symposium (Orlando, FL; June
2003). ISBN 1-57477-139-6, published by Battelle Press, Columbus,
OH, www.battelle.org/bookstore.
·
Spriggs T,
Tsangaris S, Nzengung VA, Nwokike B. 2004. Phytoremediation
of a chlorinated solvent plume in Orlando, Florida. Paper
F-13, in: V.S. Magar and M.E. Kelley (Eds.), In Situ and
On-SiteBioremediation—2003. Proceedings of the Seventh
International In Situ and On-Site Bioremediation Symposium (Orlando,
FL; June 2003). ISBN 1-57477-139-6, published by Battelle Press,
Columbus, OH, www.battelle.org/bookstore.
· *O'Niell,
W. and Nzengung,
V.A. “Field Demonstration of In-situ Bioremediation of
Perchlorate-Contaminated Soils and Groundwater,” A&WMA 96th
Annual Conference & Exhibition Proceedings. San
Diego, CA. June
22 - 26, 2003.
http://secure.awma.org/OnlineLibrary/ProductDetails.aspx?productID=2889
· *Kastner, J.R.,
Das, K.C., Nzengung, V.A., Dowd, J., Fields, J. “In-situ
Bioremediation of Perchlorate-Contaminated Soils,” Editor:
Leeson et al. 6th International. In Situ and On-Site
Bioremediation Symposium, San Diego, CA. p.289-295. 2001.
· *Nzengung, V.
A., Wang C. and Stacey B. “Phytotransformation Pathways and
Mass Balances for Chlorinated Alkanes and Alkenes,” EPA’s
Phytoremediation State of the Science Conference. Boston, MA. May
1-2, 2000. EPA Technical Publication No. EPA/625/R-01/011a November 2001.
· *Nzengung, V.
A., O’Niell, W., Adesida A. “Treatment of Perchlorate
Contaminated Water in Microbial Mat, Algae, and Ebb-and-Flow
Hydroponic Bioreactors,” Symposium Series: Case Studies in the
Remediation of Chlorinated and Recalcitrant Compounds. Editors:
Godage B. Wickramanayake, Arun R. Gavaskar, James T. Gibbs, and
Jeffrey L. Means. Battelle Press, Columbus, OH. 2(7), p.101-106.
2000.
· *O’Niell, W. and Nzengung, V. A. “Treatment of Organic Contaminated water in
Microbial Mat Bioreactors,” Symposium Series: Bioremediation and
Phytoremediation of Chlorinated and Recalcitrant Organics. Editors:
Godage B. Wickramanayake, Arun R. Gavaskar, Bruce C. Alleman, and
Victor S. Magar. Battelle Press, Columbus, OH. 2(4), p.347-252.
2000.
· Nzengung, V. A.,
Wang, C., Harvey, G., McCutcheon, S.C., and Wolfe, N.L.
“Phytoremediation of Perchlorate Contaminated Water: Laboratory
Studies,” Symposium Series: Fifth International Symposium on In
Situ and On-Site Bioremediation: Phytoremediation.
Editors; Leeson Andrea and B. C. Alleman. Battelle Press, p.239-244.
1999.
· Dhankher, O. P.,
Tucker, J., Nzengung, V. A., Wolfe, N.L. “Isolation,
Purification and Partial Characterization of Plant Dehalogenase-Like
Activity from Waterweed (Elodea Canadensis),” Symposium Series:
Fifth International Symposium on In Situ and On-Site Bioremediation: Phytoremediation. Editors; Leeson Andrea and B. C.
Alleman, Battelle Press, p.145-150. 1999.
· O’Niell, W.*, Nzengung, V. A., Noakes, J., Bender, J. and Phillips, P.
“Biodegradation of PCE and TCE Using Mixed-Species Microbial Mats” Bioremediation and Phytoremediation. Editors: G.B.
Wickramanayake and Hinchee. Battelle Press, p.233 - 237. 1998.
· Arthur W. Garrison, Nzengung, V. A., Avants, J.K., Ellington, J., and Wolfe, N.L.
“Determining the Environmental Enantioselectivity of o,p’-DDT
and o,p’-DDD,” Proceedings of the 17th International Symposium
on Chlorinated Dioxins and Related Compounds (Edited by Ronal
Hites). Vol. 31, p.256 - 261. 1997.
· Nzengung, V. A.,
Voudrias, E.A., Wampler, J.M. “A Modified Clay as Adsorbent of an
Organic Contaminant in Aqueous and Mixed-Solvent Systems” Proceedings of the 48th Industrial Waste Conference, Purdue
University, West Lafayette, Indiana, Ed. Ronald F. Wukasch,
Lewis Publishers, Chelsea, Michigan, p.387 - 391. 1993.
· Nkedi-Kizza, P. and Nzengung, V. A. “Use of the Cosolvency Model to Predict
Sorption Kinetics and Equilibria of Diuron and Naphthalene on
Organoclays,” Kearney Foundation of Soil Science International
Conference Proceedings, Vadose Zone Hydrology: Cutting Across
Disciplines. p.107 - 108. 1995.
Reports
· Mbuya, O.S. and Nzengung, V. A. 2006. Phytoremediation
of Perchlorate and N-nitrosodimethylamine as single and
co-contaminants. EPA Project Report # RD831090.
· Nzengung, V.A. 2002. “Phytoremediation of Perchlorate and Trichloroethylene
Contaminated Water.” Grant/Contract #
F6615-00-C-6060-2/10-21-RR176-261.
·
Nzengung, V.A.,
Das, K.C. and Kastner, J.R. 2001. “Pilot-Scale
In-Situ Bioremediation of Perchlorate-Contaminated Soils at the
Longhorn Army Ammunition Plant in Karnack, Texas.” Contract #
DAAA09-00-C-0060.
· Nzengung, V.A.
2001. “Phytoremediation of Perchlorate-Contaminated Soils and
Water.” Agreement #: F33615-00-2-6001.
· Nzengung, V.A. 1999. “Data on Phytotransformation Process for the Degradation of
Perchloroethene (PCE). Data Specific for the Orlando Naval Training
Center (NTC), Orlando, Florida.” USEPA/NERL, Athens-GA and US
Navy, Southern Division, Charleston-SC.
· Nzengung, V.A. 1999. “Phytodegradation Kinetics and Pathways of Perchlorate.”
Presented to USEPA-NERL, Athens, GA.
· Nzengung, V.A. 1998. “Laboratory Characterization of Phytotransformation Products
of PCE, TCE and Perchlorate.” For US Airforce, Wright Patterson
AFB, Dayton, OH and USEPA-NERL, Athens, GA.
· Nzengung, V.A.,
Voudrias, E.A., Nkedi-Kizza, P., Wampler, J.M., Weaver, C.E. 1995.
“Modified Clays as Sorbents for Aromatic Hydrocarbons in Aqueous
and Mixed-Solvent Systems.” ERC 06-95, Georgia Water Resources
Research Institute Program, Georgia Institute of Technology,
Atlanta, Georgia, 52 p. (Technical Completion Report for
USDI/Geological Survey Project 14-08-0001-G2013 (07)).
· Nzengung, V.A.,
Voudrias, E.A., Nkedi-Kizza, P., Wampler, J.M., Weaver, C.E. 1993.
“Modified Clays as Sorbents for Aromatic Hydrocarbons in Aqueous
and Mixed-Solvent Systems.” ERC 06-93, Georgia Water Resources
Research Institute Program, Georgia Institute of Technology,
Atlanta, Georgia, 56 p. (Technical Completion Report for
USDI/Geological Survey Project 14-08-0001-G2013 (07)).
International Meetings - Abstracts and Presentations
·
Nzengung, V.A. 2005. Phytoremediation of petrochemicals, perchlorate, and
chlorinated solvents in soil and groundwater. International
Conference on Energy, Environment and Disasters (INCEED 2005). Bridging
the Gaps for Global Sustainable Development (UNESCO – ISEG –
GADR). CHARLOTTE, NORTH CAROLINA, USA. July 24 - 30, 2005. · Nzengung, V.A.,
Holger Penning. 2005. “Mechanisms of Phytoremediation of
Co-contaminants: Perchlorate and Trichloroethylene (TCE).” Third
International Phytoremediation Conference. April 20 – 22, 2005.
Atlanta, Georgia. Hosted by USEPA.
· O'Niell,
W.L. and V.A. Nzengung.
2003. “Feasibility of In Situ Bioremediation of Perchlorate
Contaminated Soils.” In Situ and On-Site Bioremediation. The
Seventh International Symposium, Orlando, Florida. June 2 – 5,
2003.
· Nzengung,
V.A., Holger
Penning, and Lina Wayo. 2003. “Effects of Experimental Conditions
on Phytoremediation of Perchlorate.” In-Situ and On-Site
Bioremediation. The Seventh International Symposium, Orlando,
Florida. June 2 – 5, 2003.
· O'Niell,
W.L. and V.A. Nzengung.
2002. “Remediation of Contaminated Water Using Microbial Mats.”
8th Annual Federation of European Chemists Conference on Chemistry
and the Environment: Chemistry for a Sustaining World, Athens,
Greece, Aug. 31-Sept. 4, 2002. Environmental
Science and Pollution Research-International,
Vol. 9, Special Issue No. 3, p.70.
· Nzengung, V. A.,
Das, K.C., Kastner, J., Browber, A.G. 2001. “Laboratory and Field
Demonstration of In-Situ Bioremediation of Perchlorate-Contaminated
Soil.” The 17th Annual International Conference on Contaminated Soils, Sediment and
Water. University of Massachusetts Amherst. October 22-25, 2001.
· Nzengung, V. A.,
Kastner, J., Das, K.C. 2001. “Pilot Scale In-Situ Bioremediation
of Perchlorate-Contaminated Soil.” In-Situ and On-Site
Bioremediation. The Sixth International Symposium, San Diego,
California. June 4 – 7, 2001.
· Nzengung, V. A.,
Anna Dondero and O’Niell, W. 2001. “Phytodegradation and
Rhizodegradation of Trichloroethylene and Perchlorate.” In-Situ
and On-Site Bioremediation. The Sixth International Symposium, San
Diego, California. June 4 – 7, 2001.
· Nzengung, V. A.,
O’Niell, W., Adesida, A. 2000. “Treatment of Perchlorate
Contaminated Water in Microbial Mat, Algae, and Ebb-and-Flow
Hydroponic Bioreactors.” Symposium Series. 2nd International Conference on Remediation of Chlorinated and
Recalcitrant Compounds. Monterey, California, May 22-25, 2000.
· Nzengung, V. A.,
Wolfe, N. L., Datta, N., Rennels, D. 1998. “Uptake and
Transformation of Organic Compounds by Aquatic Plants.” First
International Conference on Remediation of Chlorinated and
Recalcitrant Compounds. Monterey, California, May 18 - 21, 1998.
· Nkedi-Kizza
P., Nzengung, V. A. 1995. “Use of the Cosolvency Model to Predict Sorption Kinetics
and Equilibria of Diuron and Naphthalene on Organoclays.” Kearney
Foundation of Soil Science International Conference, University
of California - Davis, CA.
National Meetings - Abstracts and Presentations
·
Nzengung, V.A.
Phytoremediation Mechanisms for different Types of Groundwater
Contaminants. Biochemical Engineering Program University of Georgia
Mini-Conference September 9, 2005
· Nzengung, V.A.
and Mary Elizabeth Purvis. “Low-Cost Sustainable Treatment of
Perchlorate-Contaminated Freshwater and Brines Using Surfactant
Modified Clays.” 6th Environmental Technology Symposium
and Workshop. Sustaining the Environment through Technology. March
14 – 16, 2005. Portland, Oregon.
· O’Niell, W.L. and Nzengung V.A. “In-Situ Bioremediation of
Perchlorate-Contaminated Soils and Groundwater.” The Fifteenth
Annual AEHS Meeting and West Coast Conference on Soils, Sediment,
March 2005.
· Nzengung V.A. and Walter O’Niell. “In-Situ Bioremediation of Explosives and
Perchlorate in Vadose Zone Soils and Groundwater.” SERDP/ESTCP
Annual Symposium. Washington DC. November 29 - December 2, 2004.
· Harvey, G.J.,
O’Lear, J., Godfrey, R., Nzengung V. “Perchlorate in
Marine Biota and By-products.” SERDP/ESTCP Annual Symposium.
Washington, DC. December 2-4, 2003.
· Nzengung, V. A.,
Mills, G. L. and Heath, B. “Abiotic Transformation of
Perchloroethylene (PCE) Using Dithionite Treated Clay Minerals, Iron
Oxides and Silica.” 54th Southeast Regional meeting of
the American Chemical Society (SERMACS). Charleston, South Carolina.
November 13-16, 2002.
·
Dumont, J.N.,
Burkhart J., Nzengung, V.A. “The Effects of
Ammonium Perchlorate on Reproduction of Xenopus Females.”
SETAC 23nd Annual Meeting. Baltimore, Maryland. November
11-5, 2002.
· Nzengung, V.A.,
Das, K.C., Kastner, J., and Browder, G.A. “Pilot Scale In-Situ
Bioremediation of Perchlorate Contaminated Soils at the Longhorn
Army Ammunition Plant in Karnack, Texas.” SETAC 22nd Annual Meeting. Baltimore, Maryland. November 11-15, 2001.
· Nzengung, V. A.,
Anna Dondero. “The Role of Green Plants in the Removal of
Perchlorate from Hydroponics and Organic-Rich Soils Systems.”
SETAC 22nd Annual Meeting. Baltimore, Maryland. November
11-15, 2001.
· Nzengung, V. A.,
Kastner, J., Das, K.C. “Pilot Scale In-Situ Bioremediation of
Perchlorate-Contaminated Soils.” The 6th Annual
Pollution Prevention and Hazardous Waste Management Conference. San
Antonio, Texas. August 20-23, 2001.
· Nzengung, V. A.,
and Ramaley, S. “Coupling Natural Attenuation and
Phytoremediation to Cleanup a Shallow Chlorinated Solvent Plume at
the Former Naval Training Center in Orlando, Florida.” 2001
International Containment & Remediation Technology Conference
and Exhibition. Orlando, Florida. June 10-13, 2001.
· Nzengung, V. A.,
Heath, B. and Mills, G. L. “Relative Effectiveness of Chemically
Reduced Clay Minerals and Iron Oxides in Remediation of Groundwater
Contaminated with Perchloroethene.” 37th Annual Meeting of The Clay Minerals Society, Loyola University,
Chicago, Illinois. June 24-29, 2000.
· Nzengung, V. A.,
and Payne, D. “Transformation of Chlorinated Organic Contaminants
at the Surfaces of Dithionite-Treated Glass Beads, Sands and Aquifer
Materials.” 37th Annual Meeting of The Clay Minerals Society, Loyola University,
Chicago, Illinois. June 24-29, 2000.
· Nzengung, V. A. and O’Niell, W. “Marine Algae, Microbial Mats and
Plant-Mediated Transformation of Organic Pollutants.” DOE/BI-OMP
2000. Florida A&M University, Tallahassee, Florida. March 15-16,
2000.
· Nzengung, V. A.,
C. Wang. “Influences on Phytoremediation of Perchlorate
Contaminated Water.” 218th ACS National Meeting. Special Symposium Series: Perchlorate in the
Environment. New Orleans, Louisiana. August 1999.
· Nzengung, V. A.,
Mills, G. L., Heath, B. “Transformation of Trichloroethylene
(TCE) and Perchloroethylene (PCE) at the Surface of Dithionite
Reduced Clay Minerals and Iron Oxides.” 217th American Chemical Society National Meeting, Anaheim, California.
March 21 - 25, 1999.
· Nzengung, V. A., Mills, G. L., Heath, B. “Transformation of Trichloroethylene
(TCE) and Perchloroethylene (PCE) at the Surface of Dithionite
Reduced Clay Minerals and Iron Oxides.” Southeastern Geological
Society of America Annual Meeting. Athens, Georgia. March 25 - 27,
1999.
· Nzengung, V. A. and Oates, M. T. “Sorption of Chlorobenzenes to Single- and
Dual-Cation Organo-Modified Montmorillonites.” 35th Annual Meeting of the Clay Minerals Society. Cleveland, Ohio. June 6
- 10, 1998.
· Nzengung, V. A.,
Wolfe, N. L., Carreira, L. H., McCutcheon, S. C. “Aquatic
Plants-Mediated Transformation of Halogenated Organics.” Gordon
Research Conferences, Environmental Sciences: Water. New Hampton,
New Hampshire. 1996.
· Nzengung, V. A.,
Wolfe, N. L., Carreira, L. H., McCutcheon, S. C. “Uptake and
Transformation of Halogenated Organic Contaminants by Aquatic
Plants,” Emerging Technologies in Hazardous Waste Management VIII:
1996 Book of Abstracts for the Special Symposium, Birmingham, AL,
American Chemical Society (D.W. Tedder, Editor), p 36.
· Nzengung, V. A., Voudrias, E. A., Nkedi-Kizza, P. “Changes in Shape of
Isotherms of Neutral Organics Measured in Mixed-Solvent Organoclay
System.” 33rd Annual Meeting of the Clay Minerals
Society. Gatlinburg, Tennessee. 1996.
· Nzengung, V. A.,
Nkedi-Kizza, P. “Organic Cosolvent Effects on Sorption Kinetics
of Hydrophobic Organic Chemicals by Organoclays.” 87th Annual
Meeting of ASA, CSSA and SSSA, St. Louis, Missouri. October
29 - Nov. 3, 1995.
· Nzengung, V. A.,
Voudrias, E. A., Nkedi-Kizza, P., Wampler, J.M. “Organic
Cosolvent Effects on Sorption of Hydrophobic Organic Chemicals by
Organoclays.” Gordon Research Conferences, Environmental Sciences:
Water. New Hampton, New Hampshire. 1994.
· Nzengung, V. A.,
Voudrias, E. A., Nkedi-Kizza, P., Wampler, J. M., Weaver, C.E.
“Modified Clays for the Adsorption of Aromatic Hydrocarbons from
Aqueous and Mixed-Solvent Systems.” Industrial Pollution Control
Conference, Georgia Water Pollution Control Association. Atlanta,
Georgia. February 20 - 23, 1993.
· Nzengung, V. A.,
Voudrias, E. A., Nkedi-Kizza, P., Wampler, J. M. “Organic
Cosolvent Effects on Sorption of Organic Pollutants by Four
Alkylammonium Exchanged Clays.” Emerging Technologies in Hazardous
Waste Management V: 1993. Book of Abstracts for the Special
Symposium, Atlanta, GA, Industrial and Engineering Chemistry
Division, American Chemical Society (D. W. Tedder, Editor) American
Chemical Society, Washington, DC, 1080p. 1993.
Invited Presentations of Research Papers
·
Nzengung,
V. A.
2005. Advances in Rhizodegradation of Perchlorate during
Phytoremediation. Strategic Environmental Research and Development
Program (SERDP) conference, Washington DC. November-December, 2005.· Walter O’Niell
and Nzengung, V. A. Phytoremediation of Perchlorate: Research
Presented to Scholars Committee on Perchlorate Review at the Urban
Water Research Center at the University of California, Irvine,
California. November 18 – 19, 2003.
· Nzengung, V. A.,
Wang, C. and Stacey Box. “Phytotransformation Pathways and Mass
Balances for Chlorinated Alkanes and Alkenes.” EPA’s
Phytoremediation State of the Science Conference. Boston,
Massachusetts. May 1-2, 2000
· Nzengung, V. A.,
Heath, B., Mills, G. “Enhanced Degradation of Perchloroethylene
(PCE) and Trichloroethylene (TCE) at the Surfaces of
Dithionite-Treated Clay Minerals and Aquifer Materials.”
USEPA-NERL, Athens, Georgia. March 18, 1999
· Nzengung, V. A. “How Clean Is Clean In Hazardous Waste Sites Remediation?”
Perimeter Adult Learning and Services (PALS), Dunwoody, Georgia.
June 1, 1999.
· Nzengung, V. A.
“Do Plants Have a Role In the Clean-up of Contaminated Waste
Sites?” 20 Master Gardener Volunteers. Conyers, Georgia. August
10, 1998
· Nzengung, V. A. “Phytoremediation of Perchlorate Contaminated Water.” Briefing
to Perchlorate Working Group at Wright Patterson Air Force Base,
Dayton, Ohio. August 19, 1998.
· Nzengung, V. A. “Phytoremediation of Perchlorate Contaminated Water.” Briefing
to Perchlorate Working Group at Brooks Air Force Base, San Antonio,
Texas. December 16 -17, 1998.
· Nzengung, V. A.,
C. Wang, Harvey, G., McCutcheon, S.C., and Wolfe, N. L.
“Phytoremediation of Perchlorate Contaminated Water.” 4th Annual Strategic Environmental Research and Development Program
(SERDP) Symposium, Washington, DC. December 1 - 3, 1998.
· Harvey, G.J.,
Eberts, S., Vose, J., Nzengung, V. A., Lee, R., Jones, S.
“Phytoremediation of TCE in an Alluvial Aquifer: A Field
Demonstration.” 4th Annual Strategic Environmental
Research and Development Program (SERDP) Symposium, Washington DC.
December 1 - 3, 1998.
· Nzengung V. A.,
Gates, W., Mills, G., Reyna, C. “Enhanced Degradation of
Tetrachloroethylene by Redox-Manipulated Iron-Bearing Clays and
Aquifer Material.” 3rd Annual Strategic Environmental
Research and Development Program (SERDP) Symposium, Washington DC.
December 3 - 5, 1997.
· Nzengung, V. A.,
McCutcheon, S.C., Wolfe, N. L. “Remediation of a Shallow
Groundwater Plume of PCE. TCE, DCE and VC at the Orlando Naval
Training College, Orlando, FL.” Annual USGS/DOD
Environmental Conservation Hydrology Meeting in Charleston, South
Carolina. 1997.
· Garrison, A. W, Nzengung, V.A., Avants, J. K., Ellington, J. J., and Wolfe,
N. L. “Determining the Environmental Enantioselectivity of
o,p’-DDT and Other Pesticides.” Environmental and Analytical
Chemistry of Chiral Pollutants. Invited by Dr. Renee L. Falconer.
SETAC 1997.
· Nzengung, V. A.,
Wolfe, N. L., and Carreira, L. H. “Plant-Enzyme Dechlorination of
Chlorinated Organic Compounds.” EPA Symposium on Bioremediation of
Hazardous Wastes: Research, Development, and Field Evaluations, The
Rye Town Hilton, Rye Brook, New York. August 8 - 10, 1995.
Graduate Students' Abstracts and Presentations
·
Schroer,
Katherine L., R.C. Thomas, D.M. Endale, J.W. Washington, V.
Nzengung (2006). Use of tracer injection experiments to quantify nitrate loss
in two adjacent wetland streams draining an agricultural field in
the Georgia Piedmont. Proceedings of the 2006 USDA/CSREES
National Water Conference, San Antonio, TX.
http://www.extension.iastate.edu/WaterConf2006/·
Yifru,
Dawit D., Nzengung,
Valentine,
2005. Use of dissolved organic carbon to reduce plant perchlorate
uptake during phytoremediation. Submitted to the 23rd American Chemical Society meeting (Geochemistry division),
Washington DC. August-September, 2005.
·
Yifru,
Dawit D., Nzengung,
Valentine,
2005. Removal of N-Nitrosodimethylamine from waters using sorption
and phytoremediation approaches. Submitted to the Strategic
Environmental Research and Development Program (SERDP) conference,
Washington DC. November-December, 2005.
·
Yifru,
Dawit D., Nzengung,
Valentine,
2005. Biostimulation and enhancement of rapid rhizodegradation of
perchlorate. Submitted to the Strategic Environmental Research and
Development Program (SERDP) conference, Washington DC.
November-December, 2005.
·
Schroer,
Katherine and Valentine
A. Nzengung.
2005. Distribution of N and other redox-sensitive species in two
adjacent wetland streams draining an agricultural field in the
Georgia Piedmont. 2005 Geological Society of America Annual
Conference. Salt Lake City, Utah.
· Lina
Wayo and Valentine
A. Nzengung.
2005. Bioremediation of heavy end petrochemicals with compost
amendments. International Conference on Energy, Environment and
Disasters (INCEED 2005). Bridging
the Gaps for Global Sustainable Development (UNESCO – ISEG –
GADR). Charlotte, NC, USA. July 24 - 30, 2005.
·
Dawit
D. Yifru and Valentine
A. Nzengung.
2005. Use
of dissolved organic carbon to minimize plant uptake of perchlorate.
230th ACS National Meeting in Washington, DC, Aug 28-Sept 1, 2005.
· Dawit
D. Yifru and Valentine
A. Nzengung.
2005. “Enhancement of Microbial Degradation of Perchlorate (ClO4-)
in the Rhizosphere.” In-Situ and On Site International
Bioremediation. The Eighth International Symposium. Baltimore,
Maryland. June 6 – 9, 2005.
· Dawit
D. Yifru and Valentine
A. Nzengung.
2005. “Biostimulation and Enhancement of Rhizodegradation of
Perchlorate During Phytoremediation.” 2005
NGWA Conference on MTBE and Perchlorate: Assessment, Remediation,
and Public Policy. May 26 – 27, 2005.
· Lina
Wayo and Valentine
A. Nzengung.
2005. “Biodegradation of Polycyclic Aromatic Hydrocarbons in
Compost Extract Treated Soils.” In-Situ and On Site International
Bioremediation. The Eighth International Symposium. Baltimore,
Maryland. June 6 – 9, 2005.
· Dawit
D. Yifru and Valentine
A. Nzengung.
2005. “Biostimulation and Enhancement of Rhizodegradation During
Phytoremediation of Perchlorate.” Third International
Phytoremediation Conference. Atlanta, Georgia. April 20 – 23,
2005
· Dawit
D. Yifru and Valentine
A. Nzengung.
2004. “Biostimulation of Rhizodegradation of Perchlorate (ClO4-).”
Geological Society of America. Denver, Colorado. November 2004.
· Uddin,
M.M.K., G.L. Mills, J.C. Seaman, V.A.
Nzengung.
2001. “Laboratory Studies of In-situ Redox Manipulation for
Remediation of PCE, TCE and Cr (VI) Contaminated Groundwater in
Atlantic Coastal Plain Sediments.” In: M.L. Trehy (Ed.), Preprints of paper presented at the 221st ACS National Meeting, April 1-5, 2001, San Diego, CA: American
Chemical Society: Washington, DC, 2001; vol. 41(1), p.301-306.
· O’Niell,
W. and Nzengung, V. A.
“Treatment of Organic Contaminated Water in Microbial Mat
Bioreactors.” Symposium Series. 2nd International Conference on Remediation of Chlorinated and
Recalcitrant Compounds. Monterey, California. May 22-25, 2000.
· Payne,
D. and Nzengung,
V.A. 1999. “Chemically Induced Remediation of Sediments Contaminated
with Chlorinated Aliphatics.” 217th American Chemical Society National Meeting, Anaheim, California.
March 21 - 25, 1999.
· O’Niell,
W., Nzengung,
V.A.,
Noakes, J., Bender, J., Phillips, P. 1999. “Sorption and
Transformation of Tetrachloroethylene and Trichloroethylene Using
Mixed Species Microbial Mats.” Southeastern Geological Society of
America Annual Meeting. Athens, Georgia. March 25 - 27, 1999.
· Heath,
B., Nzengung, V.A., Mills,
G. 1998. “Transformation of Perchloroethylene at the Surface of
Dithionite-Reduced Clay Minerals and Iron Oxides.” 35th Annual Meeting of the Clay Minerals Society. Cleveland, Ohio. June 6
- 10, 1998.
· O’Niell,
W., Nzengung,
V.A., Noakes, J., Bender, J., Phillips, P. 1998. “Biodegradation of PCE
and TCE Using Mixed-Species Microbial Mats.” First International
Conference on Remediation of Chlorinated and Recalcitrant Compounds.
Monterey, California. May 18 - 21, 1998.
· O’Niell,
W., Nzengung,
V.A.,
Noakes, J., Bender, J., Phillips, P. 1997. “Bioremediation of PCE
and TCE Using Mixed-Species Microbial Mats.” In Emerging
Technologies in Hazardous Waste Management VIII Special Symposium,
Pittsburgh, PA, American Chemical Society (D.W. Tedder, Editor).
· Castillo,
R., Nzengung,
V.A.,
Gates, W., Mills, G. 1997. “Enhanced Degradation of
Tetrachloroethylene by Redox-Manipulated Iron-Bearing Clays and
Aquifer Material.” 213th American Chemical Society National
Meeting. San Francisco, California. April 13-17, 1997. Vol. 37,
No. 1, p.180.
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