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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:
02.03. - 27.03.2001
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic (adaptation not specified)
Details on inoculum:
The effluent of a sewage treatment plant treating predominantly municipal wastewater was used as incolum. The effluent came frome the drainage trench of the central sewage treatment plant of the city Neustadt (ESN), in the old stool, NW-Lachen-Speyerdorf. Sampling date: 19.02.2001, Lot number: 19022001.

- Pretreatment
The inoculum was kept aerobic during transport and storage. Before the test the batch was allowed to settle for one hour.
Duration of test (contact time):
28 d
Initial conc.:
40.2 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
The test was performed as a duplicate with calculated 40.2 mg/L carbon as starting concentration. The volume of each batch was 200 mL. Additionally, a reference approach with aniline was used, a control for abiotic degradation (poisoned batch without inoculum (with 10 ml of 1% HgCl2 solution)), a control for adsorption on bacteria (poisoned batch with inoculum) and as toxicity control a test with test substance and aniline.
0.5 mL effluent of sewage treatment plant/ L batch was added. The procedure for the blank control was the same, but without addition of test substance.
The procedure was carried out at 21 ± 2 ° C without direct illumination. The test duration was 28 days. (3 ± 0.5) h after the start of the test, at the end of the test as well at five intervening times (after 2, 5, 9, 14 and 20 days) 3.05 mL sample were taken from the incubation vessels for DOC measurement. The samples were filtered and the DOC content measured.
Reference substance:
aniline
Parameter:
% degradation (DOC removal)
Value:
88
Sampling time:
28 d
Results with reference substance:
After 14 d 85% of the reference substance aniline were degraded. After 28 d a degradation of 95 % was found.
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test item can be considered as readily biodegradable
Executive summary:

The test item was tested for its ready biodegradability in the modified OECD screening test. The study procedure was based on OECD guideline No. 301 E, July 17, 1992.

The test was performed as a duplicate with calculated 40.2 mg/L carbon as starting concentration. The volume of each batch was 200 mL. Additionally, a reference approach with aniline was used, a control for abiotic degradation (poisoned batch without inoculum (with 10 ml of 1% HgCl2 solution)), a control for adsorption on bacteria (poisoned batch with inoculum) and as toxicity control a test with test substance and aniline. 0.5 mL effluent of sewage treatment plant/ L batch was added. The procedure for the blank control was the same, but without addition of test substance.

The procedure was carried out at 21 ± 2 ° C without direct illumination. The test duration was 28 days. (3 ± 0.5) h after the start of the test, at the end of the test as well at five intervening times (after 2, 5, 9, 14 and 20 days) 3.05 mL sample were taken from the incubation vessels for DOC measurement. The samples were filtered and the DOC content measured. The observed biodegradability was 88% after 28 days.

The criterion for ready biodegradability (at least 70% removal of DOC in a 10-day window) was also met in these experiment.

Thus, the substance was found to be readily biodegradable.

Description of key information

The test item was tested for its ready biodegradability in the modified OECD screening test. The study procedure was based on OECD guideline No. 301 E, July 17, 1992.

The test was performed as a duplicate. Additionally, a reference approach with aniline was used, a control for abiotic degradation (poisoned batch without inoculum (with 10 ml of 1% HgCl2 solution)), a control for adsorption on bacteria (poisoned batch with inoculum) and as toxicity control a test with test substance and aniline. 0.5 mL effluent of sewage treatment plant/ L batch was added. The procedure for the blank control was the same, but without addition of test substance.

The procedure was carried out at 21 ± 2 ° C without direct illumination. The test duration was 28 days. (3 ± 0.5) h after the start of the test, at the end of the test as well at five intervening times (after 2, 5, 9, 14 and 20 days) 3.05 mL sample were taken from the incubation vessels for DOC measurement. The observed biodegradability was 88% after 28 days.

The criterion for ready biodegradability (at least 70% removal of DOC in a 10-day window) was also met in these experiment.

Thus, the substance was found to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

A test on inherent biodegradation showed a degradation of 95 % after 23 d. Thus supporting the result of readily biodegradability of the test item.