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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:
2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
Adopted: 17 July 1992
Deviations:
no
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge: Activated sludge from aeration tank of a well-operated wastewater treatment plant receiving predominantly domestic sewage (WWTP Spišská Nová Ves).
- Pretreatment: Sludge was collected on the day of analysis. The sludge was used as collected but coarse particles were removed by settling for a short period, ca 15 minutes, and decanting the upper layer of finer solids and it was aerated by air without CO2 (CO2 was catched in the absorption flask with 0.05 mol/L NaOH) (ca 2 L/minutes) at the test temperature until it was used in the test.
- Concentration of sludge: 3.0 g/L susp. solids
- Initial cell/biomass concentration: 30.0 mg/ L suspended solids
Duration of test (contact time):
28 d
Initial conc.:
18 mg/L
Based on:
TOC
Initial conc.:
24 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral medium according to Guideline
- Test temperature: 22.3 - 24.0°C
- pH: 7.64 - 8.18

SAMPLING
- Sampling frequency: Samples were collected for TIC analysis on the 1st day, 3rd, 6th, 8th, 10th, 14th, 21st, 28th, 29th day.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 flasks
- Procedure control: 1 flask
- Abiotic sterile control: 1 flask
- Toxicity control: 1 flask
Reference substance:
other: D+glucose (C6H12O6), 12 mg DOC/L
Key result
Parameter:
% degradation (CO2 evolution)
Value:
34.73
Sampling time:
28 d

Degradation results:

Day

% Degradation

1

0.10

3

0.77

6

2.12

8

3.26

10

5.00

14

7.81

21

13.49

29

34.73

 

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
In a screening test according to OECD 301 B CO2 Evolution (Modified Sturm Test), the test item was degraded to 34.73% after 28 days.
Executive summary:

Ready biodegradability of MC A45A was tested in a screening test according to OECD 301 B. The percentage of biodegradation was determined by measurements of CO2 evolution. Due to the limited water solubility of the test item, Tween 80 was used as emulsifier.

The results of the controls indicate that the validity criteria of the test were met.

Description of key information

In a screening test according to OECD 301 B MC A45A was not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable
Type of water:
freshwater

Additional information