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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:
2016-06-20 to 2016-09-26
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
according to
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:
yes (incl. certificate)

Test material

Test material form:
Specific details on test material used for the study:
Designation: Art. 803057
Synonym: 4-(Dimethylamino)benzaldehyde
Batch: S6886257
CAS-No.: 100-10-7
Assay (GC, area%): 99.6% (a/a)
Appearance: Grey-blue, crystalline powder
Released until: May 31, 2019
Storage: Tightly closed, dark at room temperature (15 to 25°C)
ThOD: 2.24 mg O2/mg
ThOD: 2.67 mg O2/mg (with nitrification)

Study design

Oxygen conditions:
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Municipal sewage treatment plant, D-31137 Hildesheim

- Pretreatment:
The activated sludge was washed twice with autoclaved tap water. After the second washing the settled sludge was filled up with mineral salts medium and was maintained in an aerobic condition by aeration for 2-4 hours. Thereafter the sludge was homogenized with a blender. The supernatant was decanted and maintained in an aerobic condition by aeration with CO2-free air for 6 days. 10 mL/L were used to initiate inoculation.

- Concentration of sludge: 10 mL/L
- Initial cell/biomass concentration: 10^7 - 10^8 CFU/L
- Water: demineralized
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
24 mg/L
Based on:
test mat.
Initial conc.:
53.8 mg/L
Based on:
Initial conc.:
64.1 mg/L
Based on:
other: ThOD with nitrification
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Preparation of Test Flasks:
All test solutions were prepared in measuring flasks in demineralised water with the required amounts of mineral medium stock solutions and 10 mL/L inoculum. The test item was weighed out and demineralised water was added. After ultrasonic treatment it was transferred into the measuring flasks.

The reference item was weighed out and transferred into the measuring flasks with demineralised water.

250 mL measuring flasks were used to place 250 mL of the test solutions in the brown glass bottles.

A rubber sleeve with soda lime was hung into the opening of the bottles to absorb evolved CO2. The bottles were closed with Oxi-Top® measuring heads and the measuring system was activated.

The temperature in the incubator was documented continuously throughout the test by a hygrothermograph.
At test start the pH-values of the test solutions in the measuring flasks (before dividing) and at test end the pH-values of the test solutions in the brown glass bottles were determined.
The oxygen consumption was determined continuously from the pressure in the incubation vessels by OxiTop® measuring system at 360 measuring points (every 112 minutes) during the 28 d incubation period.

Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

Test performance:
Results of the Functional Control
The pass level for ready biodegradation (> 60% degradation) was reached on day 4. The validity criterion that the degradation should be > 60% after 14 d was fulfilled. Stages of Biodegradation: The adaptation phase changed to degradation phase within 1 day (degradation > 10%) and the biodegradation came to a maximum of 93% on day 24

Results of the Toxicity Control
In the toxicity control the biodegradation achieved 58% after 14 days. After 28 days the biodegradation came to 62%. The validity criterion that the test item should not inhibit the biodegradation of the reference item was fulfilled.
% Degradation
Key result
% degradation (O2 consumption)
Sampling time:
28 d
Details on results:
Both test item replicates did not reach the 10% level (beginning of biodegradation) until test end.

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
not readily biodegradable
The test item is classified as not readily biodegradable within the 28 day period of the study.
Executive summary:

The test item is classified as not readily biodegradable within the 28 day period of the study.