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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report

Materials and methods

Test guideline
according to
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
GLP compliance:
yes (incl. certificate)

Test material

Specific details on test material used for the study:
Sponsor number : Lot No. of test item : 5005108
Hydrotox number : 06/2501
Appearance : white crystalline powder
Storage conditions : keep tightly closed in a dry and cool place
Durability : 08/2008
Solubility in water : soluble

Study design

Oxygen conditions:
Inoculum or test system:
sewage, predominantly domestic (adaptation not specified)
Details on inoculum:
Secondary effluent from the municipal wastewater treatment plant Breisgauer Bucht was used as inoculum (0.1 ml per litre). The treatment plant clarifies predominantly domestic wastewater of the region of Freiburg and has a capacity of 600.000 inhabitant equivalents. The inoculum was aerated and incubated in darkness for 24 h (temperature 20.0°C). The pH of the inoculum was 8.4.
0.7 mL were added to the mineral medium for the experimentation. This corresponds to a test concentration of 2 mg/I.
Duration of test (contact time):
ca. 28 d
Initial test substance concentration
Initial conc.:
ca. 2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
- Composition of medium:
- Test temperature: 20-22°C
- pH: 7.1
- Continuous darkness: yes for 28d
- initial O2 concentration was 8.9 mg/L

- Culturing apparatus:
- Number of culture flasks/concentration: 6 bottles were filled (6 for the erythritol, 6 for the substance reference experiment, 6 for the blank)
- Method used to create aerobic conditions:
- Method used to create anaerobic conditions:
- Measuring equipment:
- Details of trap for CO2 and volatile organics if used:
- Other:

The zero-time botties were analysed immediately after filling using the electrode method. On days 4, 7, 11, 14, 21 and 28 at Ieast duplicate botties were removed for determination of dissolved oxygen and pH. If the oxygen concentrations in duplicate botties differed more than 0.3 mg/I, a third bottie was measured to confirm data. At the end of the test dissolved oxygen concentration in ail remaining botties was measured.

- Inoculum blank: An aquarium was filled with 6 I minerai medium and 0.7 ml of inoculum was added. Then the volume was made up to 7 litres. The oxygen concentration, the temperature and the pH was measured. 21 bottles were filled
- Abiotic sterile control:
- Other:
Reference substance
Reference substance:
benzoic acid, sodium salt
Sodium acetate

Results and discussion

Preliminary study:
Not specified
Test performance:
Not specified
% Degradationopen allclose all
Key result
other: % degradation is calculated : % deg BODx *100/ThOD
> 72
Sampling time:
21 d
Key result
other: % degradation is calculated : % deg BODx *100/ThOD
> 63
Sampling time:
28 d
Details on results:
On day 28 the degradation extent slightly decreased to 63 %, which is caused by increase of oxygen depletion in the blank bottles.

BOD5 / COD results

Results with reference substance:
The reference compound sodium benzoate reached the pass level for ready biodegradability within 4 days. The pH was 7.1 at the beginning of the test.

Any other information on results incl. tables

 Criteria met for the validity of the study
>    The maximal deviations for the parallel oxygen measurements at the plateau were < 20%.
>    The percentage degradation of the reference item met the criterion for biological degradation after 4 days.
>    The oxygen concentration in the test bottles never fell below 0.5 mg/1.
>    Oxygen depletion in the blanks never exceed 1.5 mg 02/1
>    The temperature in the incubator during the test remained between 20.0°C and 22°C (inside ± 1°C constant)

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
readily biodegradable
Erythritol is readily biodegradable in the closed bottle test (OECD 301D).