Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2018-06-18 to 2018-10-16
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
1992
Deviations:
no
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Municipal sewage treatment plant, 31137 Hildesheim, Germany
- Pretreatment: The activated sludge was washed twice with chlorine free tap water. After the second washing the settled sludge was resuspended in mineral salts medium and was maintained in an aerobic condition by aeration with CO2 free air until test start (2 days).
- Concentration of sludge: The amount of lnoculum used to initiate inoculation was 4.0 mL/L (25.0 mg/L dw).
- Initial cell/biomass concentration: 1E+07 to 1E+08 CFU/L; 1.36E+09/L at start
Duration of test (contact time):
28 d
Initial conc.:
38 mg/L
Based on:
test mat.
Remarks:
Corresponding to an oxygen demand of 50.2 mg O2/L (69.2 mg O2/L with nitrification)
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral salts medium according to OECD 301 F
- Test temperature: Nominal: 20 - 24 ± 1 °C; Actual: 21.0 - 21.2 °C
- pH: 7.68 to 7.53
- pH adjusted: no
- Suspended solids concentration: 25 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Number of culture flasks/concentration:
two for the lnoculum control (C1, C2)
one for the functional control (R1)
two for the test item (P1, P2)
one for the toxicity control (T1)
- Measuring equipment:
OxiTop® OC110 controller with software Achat OC, WTW
OxiTop® measuring heads, WTW
Stirring platform, WTW
Climatic exposure test cabinet, RUMED RUBARTH APPARATE GMBH
pH-Meter, Multi 350i, WTW
Datalogger 174 T, TESTO
Analytical balance, SARTORlUS
Balance, KERN
Magnetic stirrer, M83000, lab 4 you
Spectralphotometer NANOCOLORP UV/VlS, MACHEREY-NAGEL
Test Kits: Nitrat 50, Nitrit 2, all by MACHEREY-NAGEL
Multipette X-Stream, EPPENDORF
Various pipettes
- Test performed in open system: yes
- Details of trap for CO2 and volatile organics if used: A rubber sleeve with soda lime was hung into the opening of the bottles to absorb evolved CO2. The bottles were closed with OxiTop® measuring heads and the measuring system was activated.


SAMPLING
- Sampling frequency: 360 measuring points (every 112 minutes) during the 28 d incubation period.


CONTROL AND BLANK SYSTEM
- Inoculum blank: The inoculated test medium, consisting of the required volumes of mineral medium stock solutions, ultrapure water and lnoculum, was prepared in a measuring flask. 250 mL of this solution were filled in the brown glass bottles of the lnoculum control, using a
250 mL measuring flask.
- Functional control: The reference item was weighed out and transferred into a measuring flask, the required volumes of mineral medium stock solutions, ultrapure water and lnoculum, were added. 250 mL of this solution were filled in the brown glass bottle of the functional control, using a 250 mL measuring flask.
- Toxicity control: The reference item was weighed out and directly transferred into the test vessel with 250 mL test item medium (see above), using a 250 mL measuring flask.


STATISTICAL METHODS:
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
Functional control
Value:
10
Sampling time:
1 d
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
Functional control
Value:
93
Sampling time:
10 d
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
Functional control
Value:
100
Sampling time:
28 d
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
Test item P1
Value:
14
Sampling time:
28 d
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
Test item P2
Value:
17
Sampling time:
28 d
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
Toxicity control
Value:
40
Sampling time:
28 d
Details on results:
Results of the Toxicity Control
ln the toxicity control the biodegradation achieved 38% after 14 days (Table 3, Figure 1), with 40% after 28 days. The validity criterion that the test item should not inhibit the biodegradation of the reference item was fulfilled.
Course and Stages of Biodegradation of Functional Control and Test item: Both test item replicates did not reach the 60% pass level within the 28-day-period of the study. The mean biodegradation on day 28 was 16%. ThOD NO3 of 69.2 mg O2/L (i.e. with nitrification) was considered, since the concentration of nitrate increased during the test.
Results with reference substance:
Results of the Functional Control
The pass level for ready biodegradation (> 60% degradation) was reached within 3 days. The validity criterion that the degradation should be > 60% after 14 d was fulfilled. Stages of Biodegradation: The adaptation phase changed to the degradation phase within 1 day (degradation > 10%), with a maximum of 100% on day 15.

Nitrite and Nitrate Concentrations at Test End

 

Nitrite-N [mg/L]

Nitrate-N [mg/L]

corresponding oxygen consumption [mg/L]

Biodegradation calculated without nitrification [%]

Biodegradation calculated with nitrification [%]

Test item P1

0

2.30

10.51

19

14

Test item P2

0

2.19

10.00

23

17

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
In the present study conducted according to OECD guideline 301F (1992) the biodegradability of the test item was measured in a Manometric Respirometry Test for 28 days. Biodegradation reached the 10% level on day 26 and a final biodegradation of 16% on day 28, thus the test item is not readily biodegradable under the conditions of the present test.

Description of key information

According to a OECD 301F (1992) test the test item reached the 10% level on day 26 and a final biodegradation of 16% on day 28, thus the test item is not readily biodegradable under the conditions of the present test.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information