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lumnar, and Fluidized Bed Bioreactors," Oak Ridge National Laboratory, presented at the AIChE 69th Annual Meeting, Chicago, 111., Nov. 28-Dec. 2, 1976. (7) Holladay, D. W.; Hancher, C. W.; Scott, C. D.; Oak Ridge National Laboratory; Chilcote, D. D.; Hanna Mining Company / . Water Pol lut. Control Fed. 1978, No vember. (8) Krupka, M. J.: Thibault, G. T. "Biological Methods for the Detoxification of Hazardous Organic Materials," presented at the Na tional Conference on Hazardous and Toxic Waste Management, Newark, N.J., June 35, 1980. (9) Lee, D. D.; Scott, C. D., "A Tapered Fluidized-Bed Bioreactor for Treatment of Aqueous Effluents from Coal Conversion Processes," Oak Ridge National Laboratory, 1977. (10) McDowell, C. S. "Biomass Engineering Improves Wastewater Treatment System Performance," presented at the 39th Annual Meeting International Water Conference, Pittsburgh, Pa„ Oct. 31-Nov. 2, 1978. (11) McDowell, C. S.; Zitrides, T. G. "Accel erating the Dynamic Response of Bacterial Populations in Activated Sludge Systems," presented at the 34th Annual Purdue Indus trial Waste Conference, Purdue University, West Lafayette, Ind., May 8-10, 1979. (12) McDowell, C. S.; Zitrides, T. G. "Im proved Biological Wastewater Treatment Through Biomass Engineering," presented at the 1979 Annual Meeting of the California Water Pollution Control Association, San Diego, Calif., April 25-27, 1979. (13) McDowell, C. S.; Zitrides, T. G. "Mutant Bacteria: A New Tool for Wastewater Treatment," presented at the Summer Meeting of the Southern Rubber Group, Nashville, Tenn., June 16, 1978. (14) Nichols, W. E. "The Use of Freeze-Dried Microorganisms for Bulking Control and Operational Improvements," Appleton Pa pers, Inc., presented at the NCASI Central Lake States Regional Meeting, Sept. 19-20, 1978. (15) Nyer, Ε. Κ. "Operational Troubleshooting in Industrial Biological Treatment Systems," presented at the 35th Annual Purdue Indus trial Waste Conference, Purdue University, West Lafayette, Ind., May 13-15, 1980. (16) Reitano, A. J., Jr. "Startup and Opera tions of a Refinery Activated Sludge Plant," presented at the 36th Annual Purdue Indus trial Waste Conference, Purdue University, West Lafayette, Ind., May 12-14, 1981. (17) Scott, C. D.; Hancher, C. W.; Holladay, D. W.; Dinsmore, G. B. "A Tapered Fluid ized-Bed Bioreactor for Treatment of Aque ous Effluents from Coal Conversion Pro cesses," Oak Ridge National Laboratory, presented at the Symposium on Environ mental Aspects of Fuel Conversion Technol ogy, II, Hollywood, Fla., Dec. 15-18, 1975. (18) Thibault, G. T.; Elliott, Ν. W. "Biological Detoxification of Hazardous Organic Chemical Spills," presented at the 1980 Na tional Conference on Control of Hazardous Material Spills, Louisville, Ky., May 13-15, 1980. (19) Thibault, G. T.; Tracy, Κ. D. "Demon stration of a Mutant Bacterial Additive for Enhancement of Operational Stability in Oxygen Activated Sludge," presented at 34th Annual Purdue Industrial Waste Conference, Purdue University, West Lafayette, Ind., May 8-10, 1979. (20) Thibault, G. T.; Zitrides, T. G. "Biomass Engineering of Petrochemical and Refining Wastewaters," presented at the 1979 Annual Mid-Atlantic Industrial Waste Treatment Conference, Penn State University, Univer sity Park, Pa., July 16-20, 1979. (21) Tracy, K. D.; Shah, P. S. "Application of Bacterial Additives to Refinery Activated 432A
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Sludge," Exxon Research and Engineering Company, presented at the 50th Annual Meeting of the California Water Pollution Control Association, Sacramento, Calif., April 21, 1978. (22) Twedell, A. M.; Piskura, J. R.; Zitrides, T. G. "Mutant Bacteria for the Control of an Oil Spill in an Advanced Treatment Facility," presented at the Third Annual Conference on Treatment and Disposal of Industrial Wastewaters and Residues, Houston, Tex., April 18-20, 1978. (23) Wachinski, A. M„ Adams, V. D.; Reyn olds, J. H. "Research Report to U.S. Air Force Biological Treatment of the Phenoxy Herbicides 2,4-D and 2,4,5-T in a Closed System," Utah Water Research Laboratory, Utah State University, Logan, Utah, March, 1974. (24) Water Purification Associates. "Water Conservation and Pollution Control in Coal Conversion Processes," prepared for the U.S. Environmental Protection Agency, June, 1977. (25) Wei, I. W.; Goldstein, D. J. "Biological Treatment of Coal Conversion Condensates," Water Purification Associates, Cambridge, Mass., presented at the Third Symposium on Environmental Aspects of Fuel Conversion Technology, Hollywood, Fla., Sept. 13-16, 1977. (26) Wen, C. S.; Archer, T.; Kwan, J. T.; Tang, J. I. S.; Yen, T. F.; and Poulson, R. E. "Aer obic Treatment of Oil Shale Retort Water with Mutant Species;" University of Southern California and Laramie Energy Research Center. (27) Wilkinson, R. R.; Kelso, G. L.; Hopkins, F. D. "State-of-the-Art Report: Pesticide Disposal Research," Contract No. 68-032527, Midwest Research Institute, Kansas City, Mo., May, 1978. (28) Zitrides, Thomas G., "Mutant Bacteria for the Disposal of Hazardous Organic Waste waters," presented at the Pesticide Disposal Research and Development Symposium, Sponsored by the U.S. Environmental Pro tection Agency, Municipal Environmental Research Laboratory, Solid and Hazardous Waste Research Division, Reston, Va., Sept. . 6-7, 1978.
Authors' response We appreciate the listing of work on mutant microorganisms, but note that only two of the 28 citations are in refereed journals, and most would be obscure for someone trying to find in formation on waste treatment. We are aware of some of the work cited by Mr. Zitrides. For example, the two refereed papers (numbers 1 and 7) mention product names for commer cially marketed mutant bacteria. However, the two papers do not suggest that the mutant bacteria were minimally advantageous, since the treatment processes worked equally well with or without addition of mu tants. The naturally occurring and selected bacteria were able to treat the wastes. Our article promoted the use of en vironmental conditions to select and enrich for microorganisms that can biodegrade hazardous organic com pounds. Enrichment has been used for years in laboratories, the chemical and food industries, and industrial waste water treatment. Our article also
documented that microorganisms able to remove a wide variety of hazardous, anthropogenic organic compounds already exist. We attempted to bring together the necessary information to match compound type, organism type, and environmental conditions. Whether or not mutants or otherwise genetically engineered microorganisms can enhance performance is not proven. Bruce E. Rittmann Assistant Professor of Environmental Engineering University of Illinois at UrbanaChampaign Urbana, 111. 61801 Hester Kobayashi Senior R & D Chemist S O H I O Research Center Cleveland, Ohio
Microorganisms, a caveat Dear Sir: Microbial removal of hazardous organic compounds, as de scribed in the March 1982 issue of ES& T, provides us with a new means of eliminating persistent toxic chemi cals from our environment. While some microorganisms are able to de compose organic waste, however, others of the same species can trans form inorganic compounds into dan gerous organic materials. Estuarine microorganisms, for example, from both Chesapeake and San Francisco Bay areas as well as from Canadian lake sediments, as reported in Science (Vol. 215, No. 19, March 1982), are capable of transforming tin by methylation into toxic organotins that are easily mobilized into the ecosystem. Consequently, further research and carefully controlled bioengineering are essential in developing microbes that will solve pollution problems instead of adding to them. Dan Monroe Research Associate University of Tennessee Memphis, Tenn. 38163
Correction In the article "Conflict over the EPA budget" (ES&T, Vol. 16, No. 4, 1982, p. 215A), it was reported that there are between 14 000 and 20 000 hazardous waste disposal facilities in this country. There are actually this number of hazardous waste treatment, storage, and disposal facilities.
