Environ. Sci. Technol. 1982, 16, 488-492
effects noted in low biomass laboratory test systems do not occur in natural systems with higher biomass levels. One standard screening test routinely used to assess ultimate biodegradability (C02evolution) has been shown to give misleading results for OTAC (and probably for highly adsorbed cationic materials in general) because toxicity effects interfere with the test. As has been shown by others ( 2 ) )the SCAS test requires careful interpretation to distinguish between removal and biodegradation for highly adsorbed materials. Finally, the results indicate that either radiolabeled materials-or specific analytical methods-are required to make an unequivocal assessment of the ultimate fate of OTAC in waste treatment. Acknowledgments
We acknowledge the assistance of S. L. Schaeffer and A. L. Chapel1 in completing the technical aspects of this work. Literature Cited (1) “Chemical Economics Handbook”; SRI International: Menlo Park, CA. (2) Gerike, P.; Fischer, W. K.; Jasiak, W. Water Res. 1978,12, 1117-1122. (3) Janicke, W.; Hilge, G. Tenside Deterg. 1979,16, 117-122.
(4) Fenger, B. H.; Mandrup, M.; Rohde, G.; Sorensen, J. C. Water Res. 1973, 7, 1195-1208. (5) Swisher, R. D. “Surfactant Biodegradation”, Surfactant Science Series; Marcel Dekker: New York, 1970; Vol. 3. (6) Theng, B. K. G. “The Chemistry of Clay Organic Reactions”; Wiley: New York, 1974. (7) Jugerman, E. “Cationic Surfactants”; Marcel Dekker: New York, 1970. (8) Larson, R. J.; Payne, A. G. Appl. Environ. Microbiol. 1981, ‘41, 621-627. (9) Kupfer, W.; Waters, J. Anal. Chim. Acta 1976,85,241-251. (10) Larson, R. J. Appl. Environ. Microbiol. 1979,38,1153-1161. (11) Mackrell, J. A.; Walker, J. R. L. Int. Biodeterior. Bull. 1978, 14, 77-83. (12) “Wastewater Engineering Treatment Disposal Reuse”; Metcalf and Eddy, Inc., McGraw-Hill: New York, 1979. (13) Krzeminski, S. F.; Martin, J. J.; Brackett, C. K. Household Pers. Prod. Ind. 1973, 10, 22-25. (14) “Standard Methods for the Examination of Water and Wastewater”, 13th ed.; American Public Health Association: New York, 1971. (15) Dean-Raymond, D.; Alexander, M. Appl. Enuiron. Microbiol. 1977, 33, 1037-1041. (16) Osburn, Q. W. Packaged Soap and Detergent Division, Proctor & Gamble, unpublished data.
Received for review October 28,1981. Accepted March 30, 1982.
Decomposition of Nitroguanidine David L. Kaplan,” John H. Cornell, gnd Arthur M. Kaplan U.S. Army Natick Research and Development Laboratories, Environmental Protection Group, Natick, Massachusetts 0 1760
Nitroguanidine was not susceptible to aerobic biodegradation in activated sludge, and it was stable under sterile reducing conditions. Nitroguanidine was cometabolized by anaerobic sludge microorganisms to nitrosoguanidine after acclimation. There was no further microbial reduction of nitrosoguanidine (no aminoguanidine, hydrazine or urea was detected in culture extracts). Nitrosoguanidine decomposed nonbiologically and formed cyanamide, cyanoguanidine, melamine, and guanidine. All products were identified by thin-layer chromatography and mass spectroscopy. A pathway for the degradation of nitroguanidine is proposed. No ammeline, ammelide, or cyanuric acid was detected. Nitroguanidine and nitrosoguanidine were sensitive to UV light. Introduction
Nitroguanidine is used as a component of military propellants. It is water soluble, and quantities may enter the environment via discharge streams from handling facilities (1,2). Insufficient information is available in the literature on the biological fate of nitroguanidine to ysess environmental concerns. Nitroguanidine is a nitroimino compound that exists in two tautomeric forms. Form A predominates in acidic, neutral or slightly basic media (3). “2
“e ‘C=N--NO~
/
4 ‘c-NH-NO~
(1)
NH
“ 2
A
B
The purpose of this investigation was to evaluate the susceptibility of nitroguanidine to microbial degradation. 488
Environ. Sci. Technol., Vol. 16, No. 8, 1982
A further object was to gain insight into intermediate products formed during the decomposition process as well as evaluate the potential hazards associated with these compounds. Experimental Methods
Media. Basal salts contained 1.0 g of K2HP04,1.0 g of KH2P04,0.2 g of MgSO4-7H20,0.01 g of CaCl,, and 0.01 g of NaCl per liter of distilled water adjusted to pH 7.0. NH4H2P04(2.0 g/L) and glucose (1.0 g/L) were added as indicated. Nutrient broth concentrations ranged from 0.8 to 8.0 g/L. Culture Conditions. Aerobic batch cultures were incubated in 250-mL Erlenmeyer flasks each containing 100 mL of media at 30 OC on a New Brunswick G24 environmental incubator shaker. Anaerobic (unaerated) batch cultures and sterile controls were incubated at 37 “C in 250-mL Erlenmeyer flasks filled with media. Some anaerobic controls and incubations contained 0.05% DLdithiothreitol as a reducing agent. New Brunswick Bio Flo Model C30 bench-top chemostats for continuous culture were maintained under aerobic a d anaerobic conditions. The media used in aerobic chemostats were either basal salts with nitrogen and glucose or nutrient broth (2 and 4 g/L). Retention time was 7 days; the temperature was maintained at 30 “C, and the influent nitroguanidine concentration ranged from 75 to 100 ppm (pg/mL). Anaerobic chemostats were run with nutrient broth (2, 4, and 8 g/L), basal salts, basal salts with glucose, and basal salts with glucose and nitrogen. Initial retention time was 7 days and later dropped to 4 and 2 days. Nitroguanidine influent concentrations ranged from 50 to 100 ppm.
Not subject to U S . Copyright. Published 1982 by the American Chemical Society
Chemostata were operated continuously for up to 3 months at 37 "C. Aerobic cultures were inoculated with activated sludge from the Marlborough Easterly sewage treatment plant (Marlborough, MA) and anaerobic cultures with digest from the Nut Island sewage treatment plant (Boston, MA). The aerobic and anaerobic sludges contained
