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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Mar 17 - May 14, 2004
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study was performed according to GLP and the methods applied are fully compliant with OECD TG 301C.
Qualifier:
according to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):activated sludge, micro organisms from a domestic waste water treatment plant- OriginMunicipal sewage treatment plant-Conditioning:The activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in tap water and centrifuged again. This procedure was repeated twice. 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.
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
According to guideline
Reference substance:
aniline
Preliminary study:
The biodegradation in % was calculated based on the ThOD of the test item.
Test performance:
The reference item (Aniline) was sufficiently degraded to 73 % after 14 days and to 77 % after 28 days of incubation.The validity criterion that the degradation should be > 60 % after 14 d was fulfilled.
Parameter:
% degradation (O2 consumption)
Value:
-1
Sampling time:
28 d
Validity criteria fulfilled:
yes
Interpretation of results:
other: not readily biodegradable
Conclusions:
The degradation rate of the test material did not reach 60 % within the 10-day window and after 28 days of incubation. Thus the test item is not readily biodegradable.
Executive summary:

Purpose

The test item was investigated for its ready biodegradability in a Manometric Respirometry Test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the micro organisms during exposure. As a reference item aniline was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. The GLP study was performed according to OECD TG 301C.

Result

Biodegradation of test item

After correction of the mean biochemical oxygen demand of the inoculum controls at the end of the 28 -day exposure period a degradation of -1% as found.

Biodegradation of aniline

The reference item was sufficiently degraded to 73 % after 14 days and to 77 % after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum.

Conclusion

The degradation rate of the test material 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

This study was performed according to GLP and the methods applied are fully compliant with OECD TG 301C.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

This study was performed according to GLP and the methods applied are fully compliant with OECD TG 301C. For the test material, no biodegradation was observed while the reference material was readily biodegradable confirming the validity of the assay.