Successful use of technologies to accelerate bioremediation rates has been limited due to a lack of understanding of both scientific and engineering factors. For example, although a good deal is known about biodegradation pathways for organic compounds, little is known about the overall interactions of the organisms carrying out these transformations within complex communities, within geological media, or under field conditions at contaminated sites. Moreover, in many natural and engineered systems, biological processes are limited by mass transfer processes, such as molecular diffusion, that are independent of the organisms, and by an incomplete understanding of how geologic properties of the subsurface influence bioremediation. Deficiencies of engineered systems for delivering nutrients and microorganisms to various geological media have also restricted the use of bioremediation.
These research activities will build upon and synthesize information gained from all of the program elements and focus on transferring this information from the bench to the field.
Research efforts will initially focus on identifying critical processes and microorganisms necessary for promoting acceleration of bioremediation in laboratory experiments that mimic in situ conditions. Coordinated field and laboratory experiments will also be initiated. Subsequent development will include obtaining a sufficient scientific understanding of microbial and delivery processes to design meaningful field-scale experiments on accelerating the bioremediation of contaminant mixtures. It will also be necessary to develop a sufficient understanding of biostimulation and bioaugmentation processes relevant to the field research centers so that methods for accelerating bioremediation (and phytoremediation) can be tested at the field research centers. The ultimate goal of this program element is completion of the development and testing of promising strategies for accelerating bioremediation processes for contaminant mixtures at DOE sites.
Fundamental research in hydrogeology, geochemistry, and microbiology focused on understanding bioremediation rate-limiting factors associated with subsurface flow and transport of microorganisms, chemical amendments, and contaminants.
Explore and identify key bioremediation rate-limiting factors associated with chemical diffusion, advection, dispersion, dissolution/precipitation reactions, chemical complexation, volatilization of contaminants, and addition of chemical amendments. Design complementary bench and field experiments that will help provide a mechanistic understanding of key processes.
Identify key bioremediation rate-limiting factors associated with microbial transport, attachment and detachment, clogging, filtration, sedimentation, and biofilm formation in natural systems. Design complementary bench and field experiments that will help to resolve the key issues identified above.
Five-Year
Develop strategies for overcoming the bioremediation rate-limiting factors identified by efforts outlined in the three-year goals. Design complementary and iterative laboratory and field experiments to test and evaluate strategies for overcoming these rate-limiting factors.
Ten-Year
Provide a thorough scientific understanding of the factors that influence transport of microorganisms, contaminants, and additives -- and how these factors can be overcome to accelerate bioremediation rates.
Fundamental research in geochemistry, hydrogeology, and microbiology, focused on improving implementation of bioremediation strategies that optimize specific biotransformations of contaminant mixtures by microorganisms and/or plants in field environments.
Identify key limitations associated with carbon, nutrient, electron donor/acceptors, or other amendments for biostimulation and the scientific issues that need to be addressed to resolve them. Design complementary bench and field experiments that will improve understanding of these issues.
Identify key limitations of methods currently used for bioaugmentation in natural systems and the scientific issues that need to be addressed to resolve them. Design complementary bench and field experiments that will improve understanding of these issues.
Develop biostimulation and bioaugmentation strategies for the Phase II experiments (Fig. 6) at the first field research center.
Five-Year
Develop methods for implementing and optimizing newly discovered biotransformation and biodegradation processes for mixtures of metals, organics, and radionuclides.
Develop experiments for field testing new biotransformation or degradation pathways created by the Biomolecular Engineering program element.
Design biostimulation and bioaugmentation strategies for the Phase III experiments at the field research centers.
Develop methods for biostimulation and bioaugmentation to optimize the effectiveness of microbial consortia for biodegradation of contaminant mixtures.
Ten-Year
Develop and test a suite of new or improved methods of biostimulation and bioaugmentation to bioremediate priority contaminant mixtures at DOE sites.
Fundamental research in hydrogeology, geochemistry, and microbiology focused on developing effective methods that can be used in the field to deliver amendments to the subsurface for biostimulation, bioaugmentation, and increasing the bioavailability of contaminants.
Three-Year
Identify alternatives for nutrient and microorganism delivery and select one or more schemes for use in the Phase II experiments (Fig. 6) at the first field research center. Design, engineer, and implement delivery schemes for implementation in the Phase II experiments at the first field research center.
Identify key limitations associated with delivering amendments for the range of geochemical and hydrogeological conditions and priority contaminant mixtures at the DOE sites.
Five-Year
Test and evaluate preliminary delivery processes, identify limiting factors, and iterate design improvements between the laboratory and the field to overcome potential bottlenecks.
Identify remedies to overcome the drawbacks associated with displacement of pollutants from the treatment region when amendments are added.
Identify alternatives and select one or more delivery schemes for use in the Phase III experiments (Fig. 6) at the field research center.
Design delivery schemes for implementation in the Phase III experiments at the first field research center.
Ten-Year
Develop a suite of standardized delivery schemes that address the geologic and chemical diversity anticipated at DOE sites and enable implementation of bioremediation for priority contaminant mixtures.