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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Comparing the various biodegradation tests with N-methylanaline, the extent and rate of degradation differs significantly from readily to inherently biodegradable. Considering the increased degradation observed after acclimation, degradation of N-methylanaline in a STP depends on the extent of adaptation of the micro-organisms in the active sludge to this substance.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information

Evaluation of the results of the various studies:

In a 21-day biodegradation using an acclimated activated sludge inoculum, 82% mineralization and 99.9% primary degradation was obtained. It was found that degradation was faster when acclimation was performed in a single flask, rather than by an enrichment procedure.

Results of standard aerobic biodegradability tests for N-methylanilineinclude:

92% Dissolved organic carbon (DOC) in 8 days in the Zahn-Wellens test;

29 and 67% DOC removal after 28 and 42 days, in the French AFNOR test;

46% CO2 produced and 92% DOC removed in 28 days after 14 days acclimation (Sturm test);

17% DOC removal after 19 days in the OECD Screening test;

38% of the ThOD was obtained in a 5-day BOD test;

18-20% of the ThOD was expended after 5-8 days in a respiratory test using 500 ppm of the test substance;

0% of the ThOD in 30 days with a drop of sewage as an inoculum;

3% of the ThOD in 14 days in the MITI test;

8% mineralization to CO2 occurred in a 21-day test using an activated sludge as an inoculum.

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