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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:
22 Sep - 21 Oct 2016
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:
Jul 1992
GLP compliance:
yes (incl. QA statement)
Landesanstalt für Umwelt, Messungen und Naturschutz Baden-Würtemberg (29 Jun 2016).
Oxygen conditions:
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge: Municipal wastewater treatment plant, Breisgauer Bucht, Forchheim, Germany
- Storage length: The sludge was sampled on 20 Sep 2016 and the test was initiated on 22 Sep 2016.
- Preparation of inoculum for exposure: The activated sludge was washed twice with tap water by settling the sludge, decanting the supernatant and re-suspending the sludge.
- Concentration of sludge: The dry solid content of the sampled activated sludge was 3.6 g/L (mean of triplicate weight measurements after 3 h drying at 105 °C).
- Initial sludge concentration: 30 mg dry solids/L
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Initial conc.:
>= 129.1 - <= 132.1 mg/L
Based on:
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
- Composition of medium: Mineral medium
- Test temperature: 21.9 - 22.4 °C
- pH: 7.6 (initial pH), 7.6 (final pH on Day 28 in test vessels), and 7.5 (in blank vessels)
- pH adjusted: No
- Aeration of dilution water: The mineral medium was aerated for about 1 h before use.
- Suspended solids concentration: 30 mg dry solids/L

- Culturing apparatus: Oxitop-System from WTW, Weilheim consisting of narrow-necked glass bottles with rubber sleeve inserts for the CO2 trap for the absorption of the evolved CO2. Magnetic stirrers are introduced into the bottles, which are placed on a stirrer platform.
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: Aeration of mineral medium before use.
- Measuring equipment: Oxitop measuring heads with a measuring range of 500 - 1350 hPa.
- Details of trap for CO2 and volatile organics if used: Rubber sleeve inserts with NaOH pellets.
- Other: The liquid volume was fixed to 164 mL.

- Inoculum blank: Three reactors containing only inoculum.
- Toxicity control: One reactor containing the test item (232.1 mg/L) and reference compound.
- Procedure control: Three reactors containing the reference compound.
Reference substance:
acetic acid, sodium salt
Key result
% degradation (O2 consumption)
Sampling time:
28 d
Details on results:
Degradation was > 60% on Day 10.

The test item had no toxic effect on the inoculum (42.2% degradation within 4 d) according to the validity criteria of OECD 301 (< 25% on Day 14). The pH in the vessel was 8.6.
Results with reference substance:
The reference substance (sodium acetate) reached the pass level for ready biodegradability (≥ 60% ThOD and fulfilment of the 10-d window) within 8 d.
Validity criteria fulfilled:
Interpretation of results:
readily biodegradable
77.8% was degraded within the 28 days (O2-consumption). The substance is concluded to be readily biodegradable.
Executive summary:

77.8% was degraded within the 28 days (O2-consumption). The substance is concluded to be readily biodegradable.

Description of key information

77.8% was degraded within the 28 days (O2-consumption). The substance is concluded to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:

Additional information