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Biodegradation in water: screening tests

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biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Aug 01 - Sep 18, 2018
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to guideline
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
July 17, 1992
according to guideline
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Version / remarks:
EEC Publication No. L 383 A, December 1992
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Aerobic activated sludge, microorganisms from a domestic waste water treatment plant was supplied by the sewage treatment plant Rossdorf, Germany.

The aerobic activated sludge used for this study was deposited for 15 min, washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in test water and centrifuged again. This procedure was done three times. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 3.5 g dry material per litre were mixed with test water and aerated overnight. This suspension was used for the experiment.
Duration of test (contact time):
28 d
Initial conc.:
101.2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Reference substance:
benzoic acid, sodium salt
Key result
% degradation (O2 consumption)
Sampling time:
28 d
Details on results:
The mean biodegradation at test end after 28 days was 0% (ThODNH4).
Results with reference substance:
The reference item sodium benzoate was sufficiently degraded to 84% after 14 days after 28 days of incubation.
Validity criteria fulfilled:
Interpretation of results:
not readily biodegradable
The degradation rate of the test item did not reach 60 % within the 10-day window and after 28 days of incubation. Thus, the test item is not readily biodegradable.

Description of key information

OECD 301F: not readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:

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