Biodegradation of Hazardous Wastes

Biological treatment of hazardous wastes has the potential for effective, practical, and economical remediation of some Superfund sites and other hazardous waste problems. Some biological hazardous waste treatments may also be applicable for preventing the occurrence of future hazardous waste sites. From a public health perspective, this technology may allow for the treatment of environmental hazardous wastes such that potential human health effects are ameliorated, or indeed prevented, specifically by reducing the amount and toxicity of hazardous substances. Considering the importance of the environmental concerns associated with hazardous wastes, specifically from a public health perspective, a conference on the "Biodegradation of Hazardous Wastes" was held April 9-10, 1990, at Utah State University. The main purpose of the meeting, and the focus of this report, was to provide an up-to-date review of some of the biological degradation research currently available and undergoing development and to provide a forum to discuss this technology's impact on human health and the environment. In addition, current and future use of biological treatment technologies were discussed, primarily from the perspective of technology transfer; and research needs and opportunities were identified. The meeting was chaired by S. Aust, Director of the Biotechnology Center at Utah State University, and the conference was organized by a committee consisting of Aust, A. Bourquin (ECOVA), J. Fouts (NIEHS), J. Loper (University of Cincinnati), J. Salanitro (Shell Development Company), W. Suk (NIEHS), and J. Tiedje (Michigan State University). The conference brought together investigators in the fields of enzymology, microbiology, and molecular biology of hazardouswaste-degrading organisms, which included bacterial, fungal, and plant species. In addition, toxicological evaluation of biodegradation processes was discussed, essentially from the viewpoint of the agents under investigation, which consisted of the hydrocarbons, polychlorinated biphenyls (PCB), polycyclic aromatic hydrocarbons (PAH), volatile organics and chloroorganics, and benzene, toluene, ethyl benzene, and xylene (BTEX). Integrated within the context of the conference were presentations on the development of pertinent engineered systems and their applications in the field. The conference documented the potential for biological degradation of hazardous wastes and clearly reflected the many recent advances and discoveries that have been made in this rapidly moving field. Several presentations documented the metabolism of chemicals previously regarded as resistant to biodegradation, for example, bacterial systems that oxidize trichloroethylene (TCE) or dehalogenate PCB. This was perhaps the overall theme of the meeting, for at one point biodegradation of hazardous organic chemicals was described in terms of a continuum in which easily degraded organics, such as BTEX, appeared on the left, and inordinately recalcitrant compounds, such as PCB, appeared on the right. On the left are those chemicals currently thought to be amenable to degradation, and on the right are those chemicals that have not been shown to be degraded. The consensus reached during discussion periods was that continuing discoveries and development of microorganisms, and new investigations into the mechanisms of biodegradation, are combining to reduce the number and type of hard-to-degrade chemicals. This in turn means that we can more easily degrade hazardous wastes. However, it was noted that biological treatability studies will require a complete understanding of the fate and transport of contaminants and the pathway used by the organisms to degrade the chemicals. Nonetheless, there was confidence that basic research would contribute significantly toward the development of this knowledge. A panel discussion at the conclusion of the meeting noted the significant advances in the field and detailed future research needs, the strengths and weaknesses of current knowledge, and 'Biotechnology Center, Utah State University, Logan, UT 84322-4705. 2ECOVA, Corporate Office, 3820 159th Avenue, NE, Redmond, WA 98052. 'Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, 231 Bethesda Avenue, Cincinnati, OH 45267-0524. 4Shell Development Company, Westhollow Research Center, P.O. Box 1380, Houston, TX 77251-1380. 5National Institute of Environmental Health Sciences, PO. Box 12233, Research Triangle Park, NC 27709. 6Crop and Soil Science, 540 E Plant Soil Science Building, Michigan State University, East Lansing, MI 48824. Address reprint requests to W. A. Suk, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709. This paper was presented at the International Biostatistics Conference in the Study of Toxicology that was held May 13-25, 1991, in Tokyo, Japan.