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Environmental fate & pathways

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:
14 September 2016 - 12 October 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
Batch/Lot Number: 150205
Description: Blue powder
Purity: As a UVCB, purity is considered as 100%
Expiry date: 05 February 2019
Storage condition: Controlled room temperature (15-25°C, below 70 RH%)
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic, adapted
Details on inoculum:
- Source of inoculum/activated sludge: Secondary effluent, microorganisms from a domestic waste water treatment plant
- Preparation of inoculum for exposure: The secondary effluent used for this study was allowed to settle for half an hour, then the decanted effluent was aerated until use (not later than an hour).
- Pretreatment: mechanical stirring and using ultrasonic bath
- Initial cell/biomass concentration: 0.5 mL per litre
- Water filtered: yes
Duration of test (contact time):
28 d
Initial conc.:
6.055 mg/L
Based on:
COD
Initial conc.:
3.5 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Remarks:
chemical oxygen demand
Details on study design:
TEST CONDITIONS
- Composition of medium: Reconstituted Water
- Test temperature: 22 ± 2°C
- pH: 7.22
- Aeration of dilution water: yes
- Other: The secondary effluent was allowed to settle for half an hour, then the decanted effluent was aerated until use

TEST SYSTEM
- Culturing apparatus: BOD bottles (300 ml) with special neck and glass stoppers
- Number of culture flasks/concentration: 10
- Method used to create aerobic conditions: aeration
- Measuring equipment: suitable instruments
- Test performed in closed vessels due to significant volatility of test substance: yes

SAMPLING
The respective amount of the test item was weighed directly to reach the required test item concentration of 3.5 mg/L. During the preparation of the test solutions they were mixed by mechanical stirring and using ultrasonic bath to ensure a good dispersion
CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes
- Other: toxicity control
Reference substance:
benzoic acid, sodium salt
Test performance:
Concentration of Test item: 3.5 mg/L
BOD:
- 7 days: 0.07; 0.04
- 14 days: 0.03; 0.00
- 21 days: 0.06; 0.06
- 28 days: 0.09; 0.03
Key result
Parameter:
% degradation (O2 consumption)
Value:
3.3
Sampling time:
28 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
3.3
Sampling time:
21 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
0.8
Sampling time:
14 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
3.3
Sampling time:
7 d
Details on results:
Biodegradation % = ((BOD (mg O /mg Test item or Reference item))/(COD (mg O /mg Test item) or ThOD (mg O /mg Reference item)) x100
Key result
Parameter:
COD
Value:
ca. 1.73 other: mg O2/mg test item
Results with reference substance:
Concentration: 3.6 mg/L
Mean percent of biodegradation:
- 7 days: 74.2
- 14 days: 80.0
- 21 days: 84.2
- 28 days: 83.3
Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Under the test conditions the percentage biodegradation of the test item reached a mean of 3.3 % after 28 days based on the measured COD of the test item. Therefore the test item is considered not readily biodegradable.
According to the test guidelines the test item can be assumed to be not inhibitory at the applied concentration level of 3.5 mg/L on the secondary effluent microorganisms because degradation was >25 % within 14 days.

The study met the validity criteria.
The test item was not considered to have significant inhibitory effects on the secondary effluent microorganisms.
Based on the results of this study, the test item is considered not readily biodegradable.

Description of key information

Mean percentage of biodegradation based on the the measured COD of the test item after 28 days: 3.3 %

The test item is considered not readily biodegradable.

Degradation within 14 days for 3.5 mg/L applied concentration level on the secondary effluent microorganisms: >25 %

The test item can be assumed to be not inhibitory.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

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