Introduction

THE DOE MISSION

Environmental management and cleanup of the DOE facilities is one of the five primary missions of the Department of Energy (Fig. 1). To accomplish this mission, DOE must find new and more cost-effective remedies for protecting human health and the environment, particularly because of the unique composition and large quantities of hazardous and radioactive wastes that are broadly dispersed in the environment at DOE's facilities. DOE's Office of Energy Research (OER) is committed to developing fundamental scientific knowledge in support of this mission.

THE OFFICE OF HEALTH AND ENVIRONMENTAL RESEARCH

To support the environmental management mission, OER's Office of Health and Environmental Research (OHER) will initiate a new program in Natural and Accelerated Bioremediation Research (NABIR). The program plan was prepared with assistance and cooperation from DOE's Office of Environmental Management (EM) and is intended to complement EM's ongoing technology development programs by improving scientific understanding of the biogeochemical processes that provide the foundations for bioremediation.

OHER has a long tradition of sponsoring fundamental research in the life and environmental sciences. OHER investigates problems of complexity and scale that are expected to significantly change the way we think about a field of scientific inquiry. Such problems require the long-term commitment of interdisciplinary teams to develop breakthroughs in scientific understanding and new scientific methods and instruments. Examples of such programs include the Human Genome Project, the Atmospheric Radiation Measurement Program, and the Subsurface Science Program (see Table 1).

NABIR builds on this tradition and is motivated by the belief that bioremediation is an important part of the solution to DOE's environmental problems.

Figure 1. "The strategic plan of the DOE identifies five primary mission areas. (From the Performance Agreement between The President of the United States and The Secretary of Energy, Fiscal Year 1995."

Table 1. "Representative OHER accomplishments."

WHY BIOREMEDIATION

Bioremediation is defined by the American Academy of Microbiology (AAM) as "the use of living organisms to reduce or eliminate environmental hazards resulting from accumulations of toxic chemicals and other hazardous wastes" (Gibson and Sayler, 1992). Other options for remediation of soils, sediments, and groundwater include physical and chemical methods or a combination thereof. The optimal strategy for any given problem will depend on the nature and concentration of the contaminant(s), the characteristics of the hydrogeologic environment, and the extent of contamination. At the present time, bioremediation is often the preferred method for remediation of petroleum hydrocarbons because it is cost effective, and it converts the petroleum hydrocarbons into harmless by-products such as carbon dioxide and water.

Over the past decade, opportunities for applying bioremediation to a much broader set of contaminants have been identified. Indigenous and enhanced organisms have been shown to degrade industrial solvents, polychlorinated biphenyls (PCBs), explosives, and many different agricultural chemicals. Pilot, demonstration, and full-scale applications of bioremediation have been carried out on a limited basis. Equally importantly, microorganisms that transform and sequester heavy metals and radionuclides have been identified and employed, to a limited extent, for in situ bioremediation. However, the full benefits of bioremediation have not been realized because processes and organisms that are effective in controlled laboratory tests are not always equally effective in full-scale applications. The failure to perform optimally in the field setting stems from a lack of predictability due, in part, to inadequacies in the fundamental scientific understanding of how and why these bioremediation processes work.

The advantages of in situ bioremediation compared to or in combination with other remediation technologies include, but are not limited to, the following.

1. In situ bioremediation can be used to completely degrade and detoxify some organic contaminants, thereby permanently removing liability for the contaminants.

2. For deep, widely dispersed plumes of heavy metals and radionuclides, in situ biosequestration and immobilization may be the only viable solution for addressing DOE's remediation needs.

3. For some types of contaminants, physical and chemical methods of remediation may not completely remove the contaminants, leaving residual concentrations that are above regulatory guidelines. Bioremediation can be used as a cost-effective secondary treatment scheme to decrease the concentration of contaminants to acceptable levels. In other cases, bioremediation can be the primary treatment method, and followed by physical or chemical methods for final site closure.

4. In some cases, natural attenuation (including natural bioremediation) of the contaminant plumes may be the only cost effective solution (DOE, 1995). Natural biogeochemical processes that degrade organic contaminants, convert nitrate to nitrogen gas, and sequester heavy metals and radionuclides will play major roles in natural attenuation. These biogeochemical processes must be adequately understood before regulatory agencies and the public accept natural attenuation as an alternative to more aggressive remediation methods.

5. For radionuclides and heavy metals broadly dispersed in surface soils, phytoremediation (bioremediation using plants) may be the only practical way to concentrate and collect the contaminants. Alternatively, plants that do not accumulate radionuclides or heavy metals can be planted to prevent wildlife exposure to contaminated sources of food.

6. In highly heterogeneous geologic environments, physical or chemical methods that rely on advective transport of remediation agents to the contaminants may be ineffective. However, in such environments, in situ remediation schemes that rely on diffusive transport of remediation agents (e.g., nutrients) to indigenous microorganisms for degrading or transforming the contaminants may be more effective.

7. For complex mixtures of contaminants requiring a combination or sequence of physical and chemical remediation methods, bioremediation techniques that use microbial consortia to concurrently address all contaminants may be faster and more cost-effective.

 NABIR will support fundamental research on natural and accelerated bioremediation. Both are expected to significantly reduce the cost and improve the effectiveness of remediation of DOE's contaminated sites. Although this program emphasizes fundamental research on in situ bioremediation of soils and groundwater, knowledge applicable to ex situ waste treatment schemes will be learned and transferred. Similarly, this program will focus on microbial bioremediation, compared to phytoremediation, because the majority of DOE's contaminants are below the rhizosphere. However, when appropriate, phytoremediation research will also be sponsored.

THE NABIR PROGRAM PLAN

The NABIR program plan covers a ten-year period beginning in FY 1996. The plan presented here describes the motivation for and structure of the scientific program, the scientific goals and objectives, and the plans for partnering with EM, regulatory agencies, and the public to facilitate implementation of the scientific knowledge gained. A management structure, implementation plan, schedule, and budget are also provided.

WHO WILL PARTICIPATE IN THE NABIR PROGRAM?

Participants in the NABIR program will include the national research community, the EM problem holders, and federal officials with management and oversight responsibilities. The national research community will be engaged in the broadest sense, including academic, DOE laboratory, other federal agency, and industrial researchers.

Research projects will be carried out by teams of laboratory scientists and engineers, academic researchers, postdoctoral fellows, graduate students, and field technicians. The scientific teams will be selected through a competitive process, and research projects will be formally peer-reviewed biannually. Periodic scientific forums will be held to stimulate the transfer of ideas and information between researchers and to help guide the direction of the scientific program. Programmatic peer reviews will be conducted prior to critical decision points in the program. The scientific direction of the program and its projects will be adjusted in response to these two types of peer review and broader input from the scientific community. In addition, a multi-agency steering committee will be established to provide coordination between complementary research and technology development programs.

Integration of the scientific research among the investigators will be key to the success of the program. Three field research centers will be established for performing long-term, interdisciplinary, multi-investigator research and will be the primary integrating vehicles for the research program. Large-scale, multi-investigator field experiments will be conducted to bring together researchers from a variety of scientific and engineering disciplines. In addition, the field research centers will be available for investigator-initiated research by scientists funded from this and other programs.

The field research centers also will be critical for ensuring that the knowledge gained from NABIR will be used to help solve DOE's environmental management problems. Locating the field research centers at DOE facilities will provide ongoing opportunities for a two-way transfer of information between the EM problem holders and the research community. Researchers will learn more about site-specific needs for fundamental and applied research. Site personnel responsible for the cleanup will keep abreast of the latest scientific developments and new opportunities for applying bioremediation.

Return to Contents

Previous Section

Next Section