Melamine

Endpoint summary

Additional information

Test results of a MITI test for ready biodegradability, 3 Zahn-Wellens assays for inherent biodegradability and 2 studies on Biochemical Oxygen Demand are reported. The individual results of the studies are consistent: Melamine is not readily biodegradable and also not inherently biodegradable.

Addition of glucose, in the absence of NH4+, enables the microorganisms to use melamine as only nitrogen source (Fimberger 1997).

With activated sludge taken from an industrial waste water treatment plant as the inoculum, a degradation of up to 16 % was observed within 20 d (Pagga 1991). A rapid and complete primary degradation of the molecule within 8 h was detected with an activated sludge taken from an industrial waste water treatment plant from a producer of melamine (Fimberger 1997).

Degradation occurs by hydrolytic deamination to ammeline, ammelide and cyanuric acid, and lastly to CO2 and NH4+ (Fimberger 1997).

Nitrification was investigated in soil (Hauck 1964): Nitrification of melamine from powders was slightly greater than from solutions and considerably greater than from granules of these materials. Up to ca. 18 % of the nitrogen in the molecule are converted to nitrate within 24 weeks.

Nitrification was also observed by specific strains of Pseudomonas, Nitrosomonas and Klebsiella (Hockenbury 1977, Tillmann 1990, Jutzi 1982 and Bollag 1991).

Identification of degradation products:

Degradation products were identified by Jutzi 1982 (Chapter 6.5), Bollag 1991 (Chapter 6.5) and Fimberger 1997 (Chapter 5.2.1). A weight of evidence approach is applied. Degradation occurs by hydrolytic deamination to ammeline, ammelide and cyanuric acid, and lastly to CO2 and NH4+.