This research deals with one of the fundamental problems in implementing bioremediation, the variability in microbial populations and environmental conditions in the subsurface. At arid Western sites and at humid Eastern sites, field-oriented research is being directed toward characterization of microbial heterogeneity and the relationship of microbial heterogeneity to geochemical and physical heterogeneity. A second stage is examining how this underlying heterogeneity affects stimulation of the microbial populations in bioremediation.
Subsurface Science Program: Bacterial Transport
This research focuses on basic research applicable to the bioaugmentation approach to bioremediation. Basic processes controlling bacterial transport are being investigated in the laboratory and in ongoing field experiments at an uncontaminated field site where natural physical and chemical heterogeneity are reasonably well understood. The coarse-grained, sandy sediments at the site have stringers of high iron content, and the hypothesis for the field experiment deals with the effect of the iron on bacterial transport. Microbial characteristics and microbial interactions controlling transport are key questions being addressed.
Subsurface Science Program: Co-Contaminant Chemistry
This research deals most directly with bioremediation-related issues by addressing the increased mobility of radionuclides in the subsurface due to chelation with organic matter. This mobility may be reduced to prevent movement of the radionuclides by degradation of the organic chelator or displacement of the radionuclides from the chelator. Issues such as sorption of the radionuclides, chelators, and the complex are being addressed.
Subsurface Science Program: Deep Microbiology
This research focuses on the deep biosphere, including deep aquifers, sediments and lithologies, where in situ bioremediation may be the only feasible remediation option. Emphasis is being given to deep microbial ecology and to the origins of microbiota found at depths of hundreds of meters or more. For origins research, the two main hypotheses are the in situ hypothesis that the origin of the microorganism is associated with the original depositional environment and the transport hypothesis that microorganisms have been transported into the current geological environment from elsewhere. Aspects related to bioremediation include survival characteristics of bacteria in the subsurface, long-term and long-distance transport of bacteria, acquisition of microorganisms with new degradative and survival capabilities, and enhanced understanding of the unusual environmental factors that control the presence and distribution of deep microbial populations.
Basic Energy Sciences: Geosciences Program
The BES Geosciences Program supports a wide variety of fundamental research in geophysics, geochemistry, geomechanics, and subsurface flow and transport. Many of the projects are developing knowledge relevant to bioremediation, including subsurface imaging, thermodynamic and kinetic behavior of complex mixtures of chemicals, and transport of reactive chemicals in heterogeneous environments.
Basic Energy Sciences: Chemical Sciences Program
The BES Chemical Sciences Program supports a wide variety of fundamental research in combustion, solar photoconversion, catalysis, separation and analysis, and fundamental research to support environmental restoration and waste management. Many of these projects may be indirectly related to bioremediation, especially those investigating radiochemistry, advanced analytical and spectroscopic methods, and major R&D facilities.
Basic Energy Sciences: Material Sciences
The BES Material Sciences Program supports a wide variety of fundamental research in the chemistry of materials, including the chemical and crystalline structure of liquids and solids; polymers and organic materials, including superconductors, magnetic materials, semiconductors, and conductors; and surfaces, interfaces, and surface chemistry. They also support research in solid-state physics, including the mechanical and acoustic properties of liquids and solids, phase transition and thermodynamics, and thin films. Many of these projects are indirectly related to bioremediation, especially those involving interfaces and surface chemistry and new methods for characterizing materials.
Basic Energy Sciences: Energy Biosciences
The BES Energy Biosciences Program supports research in energy-related microbiology, metabolic diversity, photosynthesis, and plant cell walls. Many of these programs are indirectly related to bioremediation, especially those applicable to phytoremediation.
Adsorption/Desorption Processes and Bioavailability
Research in this area focuses on developing the technology necessary to accelerate rates of in situ biological remediation of sorbed contaminants. Two approaches are to use surfactants/biosurfactants to enhance the bioavailability of contaminants, and to isolate adhesion-deficient bacteria as a biocatalyst for trichloroethylene (TCE) degradation.
Biomass Remediation
The goal of this research project is to demonstrate the feasibility of using terrestrial and aquatic plants to remediate soils, sediments, and surface waters contaminated by heavy metals and radionuclides. Feasibility is evaluated by investigating the accumulation of contaminants in plants grown on contaminated soils relative to the concentration of the contaminant in the soil, and by using the Ukrainian fractionation separation technology (FST) to establish the distribution of the contaminants in the plant biomass.
PCB Bioremediation
This research deals with developing and demonstrating a bioremediation technology for polychlorinated biphenyl (PCB) contaminated soil and sludge. General Electric Company (GE) has provided a microbial culture that is known to degrade PCBs. The development of new ways to stimulate PCB degradation by this microbial culture will ultimately result in complete mineralization of the PCBs.
Biosorption of Uranium
The focus of this research is to develop a biosorbent technology (sorptive biomass) that selectively removes uranium or other selected metals present at low concentrations in surface or groundwater. Biosorbents immobilized in permeable beads are used in flow-through bioreactors to achieve waste fixation and volume reduction (ppm levels reduced to ppb levels).
Co-Metabolic Techniques for Biodegradation of TCE
The co-metabolic bioremediation of mixed organics at DOE sites is the focus of this research. Field-scale bioreactors are used to demonstrate degradation of compounds not used as a carbon or energy source by microorganisms. Microorganisms used include methanotrophs and pseudomonads which degrade toluene.
In Situ Microbial Filters
The goal of this research is to develop and evaluate an in situ microbial filter of methanotrophic bacteria to remediate contaminated plumes at their expanding boundaries. Contaminated groundwater that flows through the microbial filter will be decontaminated to regulatory limits by the microorganisms, and clean water will be produced.
Vadose Zone Bioremediation of Chlorinated Solvents
The objective of this research is to develop and evaluate the effectiveness of various classes of microorganisms to degrade chlorinated solvents in groundwater and to test methods to control the metabolic activity of multiple populations of microorganisms in the subsurface.
The goal of this work is to recommend effective designs of chemical delivery, mixing schemes, and strategies for improving in situ bioremediation. This will be accomplished by conducting laboratory work, evaluating field data, and investigating processes of solute transport and fate.
Field Demonstration of In Situ Biodegradation of TCE and PCE Using Methane
This project has three approaches to the degradation of TCE and PCE using methane. One approach is to use horizontal wells to inject air or an air/methane mixture into soil, which stimulates indigenous microorganisms to degrade the TCE and PCE. Another approach is to pump contaminated groundwater through a fermenter containing methane. The indigenous methanotrophic bacteria in the groundwater are thus stimulated to degrade the contaminants. The third approach is to use microorganisms already present in the roots of trees and plants (rhizospheres containing methanotrophs) to degrade TCE and PCE.
Biodegradation of Carbon Tetrachloride at Hanford
Studies are being conducted to identify optimal strategies for co-metabolic degradation of carbon tetrachloride, including evaluation of acetate, glycerol, methanol, and ethanol as agents for biostimulation.
Bioremoval of Metals with Algae
Studies are being conducted on the ability of algae to remove metals from water while embedded in polyurethane foam. This bioremoval technology could be used to remediate groundwater and surface water impoundments contaminated with heavy metals.
Bioremediation of Petroleum-Contaminated Soil in a Prepared Bed
This full-scale bioremediation system for petroleum-contaminated soil consists of a cement trough 400 ft long by 40 ft wide with four cells. Each cell is being used to test different nutrient amendments for stimulating indigenous microbes to degrade petroleum contaminants.
In Situ Bioremediation of Groundwater at a Sanitary Landfill
Air and gaseous nutrient injection to accelerate bioremediation are being demonstrated at two sites in a large sanitary landfill. The groundwater is contaminated with chlorobenzenes, vinyl chloride, and trichloroethylene.
Passive Bioventing of Petroleum-Contaminated Vadose Zones
Demonstrations of barometric pumping (passive gas flow) are being done for vadose zones contaminated with petroleum hydrocarbons or chlorinated solvents.
Active Bioventing/Biosparging of Petroleum-Contaminated Vadose Zones
Air is being extracted and injected at several sites to demonstrate bioremediation of petroleum hydrocarbons in vadose zones.
Other indirectly related programs include research in bioconversion of coal, bioprocess engineering to develop new technologies for alcohol fuels and pollution prevention technology for waste streams, methods of microbially enhancing recovery from oil reservoirs, and microbial and enzymatic methods to remove sulfur from petroleum.