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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:
start: 2008-07-01 end:2008-10-08
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
reference to other study
according to guideline
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No test surrogate or analogue material.
Oxygen conditions:
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The inoculum came from the activated sludge of the biological wastewater treatment plant from Abidos (France, 64). No data on sampling depth, sampling procedure, and contamination history.

- Laboratory culture:
- Method of cultivation: no data
- Storage conditions: no data
- Storage length: 2 days

- Preparation of inoculum for exposure:
- Pretreatment: The inoculum was preconditioned (aeration) until the flasks were inoculated.
- Concentration of sludge: The effluent, obtained 2 days before seeding the flasks, was centrifuged at approximately 20 °C for 20 min at 4000 g; the base was resuspended in dilution water in order to keep the concentration unchanged with respect to the sample.
- Initial cell/biomass concentration: The amount of dry material in the inoculum, determined by desiccation at 105 °C until a constant weight is obtained, was 6.03 g/L.
- Water filtered: no data
- Type and size of filter used, if any:
Duration of test (contact time):
ca. 28 d
Initial conc.:
ca. 50 mg/L
Based on:
test mat.
Initial conc.:
ca. 130 mg/L
Based on:
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
- Composition of medium: The composition of the dilution water is being decribed extensively in the original study report, Annex 1
- Additional substrate: not applicable
- Solubilising agent (type and concentration if used): not applicable
- Test temperature: 22± 2°C
- pH: 7.4
- pH adjusted: not reported
- CEC (meq/100 g): not applicable
- Aeration of dilution water: no data
- Suspended solids concentration: 30 mg/l
- Continuous darkness: not reported
- Other:

- Culturing apparatus: Sapromat, volume of flasks 500 ml volume of test solution 250 ml in each flask
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: strirring
- Method used to create anaerobic conditions: not applicable
- Measuring equipment: The C02 generated by the ultimate biodegradation process is fixed by the soda lime. A drop in pressure ensues, which is detected by the manometer and sent to the control unit. In return, this sends an electrical current into the oxygen generator, which generates electrochemically an amount of oxygen in proportion to the intensity of the electrical current.
- Test performed in closed vessels due to significant volatility of test substance: yes
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: The soda lime placed in the reactor's capsule.
- Other:

- Sampling frequency: not applicable
- Sampling method: not applicable
- Sterility check if applicable: sterile control flask running in parallel with test flasks
- Sample storage before analysis: not applicable
- Other:

- Inoculum blank: inoculum in dilution water only
- Abiotic sterile control: sterile water plus test item
- Toxicity control: test item plus reference item
- Other: mthod control: reference item plus inoculum

STATISTICAL METHODS: no statistics applied
Reference substance:
benzoic acid, sodium salt
Preliminary study:
not applicable
Test performance:
The following performance criteria have been met:
The difference of extremes of replicate values of the removal of test chemical at the plateau, at the end of the test, or at the end of the 10-d window, was less than 20 %;
The percentage degradation of the reference item reached a level of 80 % by 14 days which is above the required level of 60 %;
The oxygen uptake of the inoculum blank was of about 42.4 mg 02/L in 28 days, which is below 60 mg 02/L;
The pH value in the test suspension was 7.8 at day 28, which is in the range of 6-8.5;
In the toxicity control flasks, containing both the reference item and 10-UNDECENOIC ACID, the percentage of biodegradation reached 70 % after 14 days. Since this value is higher than 25%, the test item is not inhibitory for inoculum.
Key result
% degradation (O2 consumption)
ca. 94
St. dev.:
Sampling time:
28 d
% degradation (O2 consumption)
ca. 88
Sampling time:
21 d
% degradation (O2 consumption)
ca. 74
St. dev.:
Sampling time:
10 d
% degradation (O2 consumption)
ca. 70
Sampling time:
7 d
% degradation (O2 consumption)
ca. 56
Sampling time:
4 d
ca. 2.46 g O2/g test mat.
Results with reference substance:
The percentage degradation of the reference item reached a level of 80 % by 14 days which is above the required level of 60 %

No remarks

Validity criteria fulfilled:
see section "test performance"
Interpretation of results:
readily biodegradable
According to OECD guideline 301, 10-UNDECENOIC AClD is readily biodegradable.
Executive summary:

The objective of this study was to determine the "ready" ultimate aerobic biodegradability of the test item 10-UNDECENOIC AClD by applying the procedure described in the OECD Guideline 301 F. According to the OECD guideline 301, the pass level for ready biodegradability is 60 % of Theoretical Oxygen Demand (ThOD). This level has to be reached in a 10-d window within the 28-d period of the test. The 10-d window begins when the degree of biodegradation has reached 10 % of ThOD and must end before day 28 of the test. Under the test conditions, the percentage of biodegradation of 10-UNDECENOIC AClD reached 94 % of the ThOD at the end of the test (28 days). At the end of the 10-d window the percentage of biodegradation is already 74 % of the ThOD. Therefore, according to OECD guideline 301, 10-UNDECENOIC AClD is readily biodegradable.

Description of key information

Two Klimisch-1-rated studies were carried out on ready biodegradability, i.e. a CO2 evolution test (1996) and a manometric respirometry test. Whereas in the CO2 evolution the test substance did not reach the 60% degradability criterion (51% degradation in 28 days), the study with the manometric respirometer revealed a degree of degradability of 94%, thus the substance clearly was readily biodegradable under the conditions of this study. Since the manometric respirometry test was considered to have delivered data of higher validity and reliability, undecylenic acid is considered readily biodegradable. 

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:

Additional information