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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From May 20, 2005 to June 17, 2005
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Cross-reference
Reason / purpose:
read-across source
Reference

A closed bottle ready biodegradation study was performed to assess the ready biodegradability of the read across substance, amides, C16-18, N-(hydroxyethyl), with non-adapted municipal activated sludge according to OECD Guideline 301 D, in compliance with GLP. The test substance concentration was 3.33 mg/L, corresponding to 10.22 mg O2/L in the test vessel. Degradation was analysed by measuring the oxygen concentrations over a period of 28 d. Biodegradation was expressed as the percentage BOD and calculated for each oxygen analysis. Sodium acetate was used as the reference control at 10 mg/L. The test substance reached the 10% level (begin of degradation) after 2 d. The pass level of >60% was reached after 17 d. The degradation reached a maximum of 69% after 28 d. The biodegradation for the reference substance reached 68% after 14 d. All the validity criteria according to the guideline were fulfilled. Under the test conditions, the test substance was considered readily biodegradable (Fiebig, 2005).

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2005
Report Date:
2005

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
yes
Remarks:
; there was slight higher oxygen depletion in the inoculum control; however it has no impact on the quality and integrity of the study.
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic, non-adapted
Details on inoculum:
-Source of inoculum/activated sludge: Municipal sewage treatment plant, D-31137 Hildesheim
-Pretreatment: The activated sludge was filtered with folded filter. The first 200 mL of the filtrate was not used. The second filtrate effluent from the domestic waste water was used to initiate inoculation.
-Colony forming units in the test vessels: 104-106 CFU/L
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
3.33 mg/L
Based on:
other: test concentration (i.e., equivalent to COD of 10.22 mgO2/L; ThOD of 9.03 mgO2/L )
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral nutrient solution according to to OECD 301 D
- Test temperature: 20-24 (constant ± 1°C)
- pH: 7.52
- Continuous darkness: yes, in an incubator
- Dispersion treatment: Agitation

TEST SYSTEM:
- Culturing apparatus: 300 mL BOD bottles with glass stoppers
- Number of culture flasks/concentration: Duplicates
- Method used to create aerobic conditions: Aerated until oxygen saturation

SAMPLING:
- Oxygen consumption was measured on Day 0, 7, 14, 21 and 28.

CONTROL AND BLANK SYSTEM
Inoculum control: Nutrient solution and inoculum
Toxicity control: 100 mL of test substance (1.67 mg/L) + 5 mg/L reference substance + nutrient solution and inoculum

PERFORMACE OF THE TEST: Based on the chemical oxygen demand (COD) the test concentration of 3.33 mg/L corresponding to oxygen demand of 10.22 mg O2 in the vessel was selected. Inoculum (0.2 mL) and test substance in a mineral culture medium were placed in closed flasks and kept at a constant temperature of 20-24 (constant +/- 1°C) in the dark in an incubator. Oxygen consumption of the inoculums control, functional control, test substance and toxicity control was determined.
Reference substance
Reference substance:
acetic acid, sodium salt
Remarks:
at 10 mg/L (ThOD = 0.78 mgO2/mg)

Results and discussion

Preliminary study:
None
Test performance:
No data
% Degradation
Key result
Parameter:
% degradation (O2 consumption)
Value:
69
Sampling time:
28 d
Details on results:
- Inoculum control: The oxygen demand in the inoculum control came to 2.11 mgO2/L after 28 d.
- Toxicity control: The biodegradation rate came to 51% after 14 d and reached 65% after 28 d.

BOD5 / COD results

Results with reference substance:
For the reference substance, the pass level of >60% was reached after 11 days. After 28 days, the biodegradation reached 74%.


Any other information on results incl. tables

None

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
There was slight higher oxygen depletion (>1.5 mg O2/L) in the inoculum control; however it had no impact on the quality and integrity of the study.
Interpretation of results:
readily biodegradable
Conclusions:
Under the test conditions, the test substance was considered to be readily biodegradable with 69% degradation after 28 d.
Executive summary:

A closed bottle ready biodegradation study was performed to assess the ready biodegradability of the test substance with non-adapted municipal activated sludge according to OECD 301D. The test substance concentration was 3.33 mg/L, corresponding to 10.22 mg O2/L in the test vessel. Degradation was analysed by measuring the oxygen concentrations over a period of 28 days. The biodegradation is therefore expressed as the percentage BOD and was calculated for each oxygen analysis. Sodium acetate was used as the reference control at 10 mg/L. The test substance reached the 10% level (begin of degradation) after 2 days. The pass level of >60% was reached after 17 days. The degradation reached a maximum of 69% after 28 days. The biodegradation for the reference substance reached 68% after 14 days. All the validity criteria according to the guideline were fulfilled. Under the test conditions, the test substance was considered readily biodegradable (Fiebig, 2005).