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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:
Not reported
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:
not specified
Remarks:
(Toxicity control)
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Details on inoculum:
- Source of inoculum: Sewage treatment plant, Hochdahl
- Concentration of sludge: 1 mL/L
- Initial cell/biomass concentration: 1,000-100,000 cells/mL
- Type and size of filter used: Effluent was filtered through coarse paper filter, first 200 mL being discarded
Duration of test (contact time):
30 d
Initial conc.:
2 mg/L
Based on:
act. ingr.
Initial conc.:
5 mg/L
Based on:
act. ingr.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Solubilising agent (type and concentration if used): Emulsifier NP 9, 5EO 5PO (2 & 5 mg/L)
- Test temperature: 19.4-20.4 °C
- Aeration of dilution water: Prior to treatment, water was aerated with compressed air by means of a sintered glass tube until O2 saturation (8-9 mg O2/L) was reached


TEST SYSTEM
- Culturing apparatus:
- Number of culture flasks/concentration: 4 (inoculum blank); 2 (treatment)
- Measuring equipment: O2 levels measured by Winkler titration
- Test performed in closed vessels: Yes


SAMPLING
- Sampling frequency: 0, 5, 15 & 30 d after treatment


CONTROL AND BLANK SYSTEM
- Inoculum blank: Containing inoculated test medium
- Procedure control: Containing reference substance
- Vehicle control: Containing inoculated test medium and emulsifier (2 & 5 mg/L)
Reference substance:
other: Dodecylsulfate, 1.89 mg/L
Parameter:
% degradation (O2 consumption)
Value:
>= 56 - <= 60
Sampling time:
5 d
Parameter:
% degradation (O2 consumption)
Value:
>= 71 - <= 82
Sampling time:
15 d
Parameter:
% degradation (O2 consumption)
Value:
>= 74 - <= 82
Sampling time:
30 d
Details on results:
% degradation:
- 2 mg/L test material + 2 mg/L emulsifier: 56, 82 & 82 after 5, 15 & 30 d, respectively
- 5 mg/L test material + 5 mg/L emulsifier: 60, 71 & 74 after 5, 15 & 30 d, respectively
- 2 mg/L emulsifier: 1, 2 & 0 after 5, 15 & 30 d, respectively
- 5 mg/L emulsifier: 1, 1 & 2 after 5, 15 & 30 d, respectively

Chemical Oxygen Demand (COD) of the test substance determined by DIN-method 38409 part H41-1 was 2.23 mg O2/mg test substance.
Theoretical Oxygen Demand (THOD) of the emulsifier, based on structural formula was 2210 mg O2/g NP 10EO+5PO.
Parameter:
COD
Value:
2 230 mg O2/g test mat.
Results with reference substance:
- % degradation: 51, 77 & > 100 after 5, 15 & 30 d, respectively
- Theoretical Oxygen Demand (THOD), based on structural formula: 2.02 mg O2/mg dodecylsufate

None

Validity criteria fulfilled:
not specified
Remarks:
(Toxicity control not reported)
Interpretation of results:
readily biodegradable
Conclusions:
Under the test conditions, the test substance underwent 74-82% degradation within a 30 day period. Since the pass level (i.e., 60% ThOD) was reached, the substance can be considered as readily biodegradable.
Executive summary:

An OECD Guideline 301 D (Closed Bottle) test was conducted to determine the biodegradability of the test substance in an aerobic aqueous medium. The test (2 and 5 mg/L with 2 and 5 mg/L emulsifier, respectively) and reference (dodecylsulfate, 1.89 mg/L) substances were inoculated with the effluent of domestic sewage, kept in completely filled closed bottles and observed for degradation by measurement of the dissolved oxygen concentration over a 30 day period. Degradation of the test substance was determined to be 56-60%, 71 -82% and 74 -82% after 5, 15 and 30 days, respectively. Chemical Oxygen Demand (COD) of the test substance determined by DIN-method 38409 part H41-1 was 2.23 mg O2/mg test substance. The degradation of the reference substance was determined to be 51, 77 and >100% after 5, 15 and 30 days, respectively. The Theoretical Oxygen Demand (ThOD) of the reference substance was calculated on the basis of its structural formula to be 2.02 mg O2/mg dodecylsufate. In conclusion, the test substance underwent 74-82% degradation within a 30 day period. Since the pass level (i.e., 60% ThOD) was reached, the substance can be considered as readily biodegradable (Richterich, 2001).

Description of key information

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

An OECD Guideline 301 D (Closed Bottle) test was conducted to determine the biodegradability of the test substance in an aerobic aqueous medium. The test (2 and 5 mg/L with 2 and 5 mg/L emulsifier, respectively) and reference (dodecylsulfate, 1.89 mg/L) substances were inoculated with the effluent of domestic sewage, kept in completely filled closed bottles and observed for degradation by measurement of the dissolved oxygen concentration over a 30 day period. Degradation of the test substance was determined to be 56-60%, 71 -82% and 74 -82% after 5, 15 and 30 days, respectively. Chemical Oxygen Demand (COD) of the test substance determined by DIN-method 38409 part H41-1 was 2.23 mg O2/mg test substance. The degradation of the reference substance was determined to be 51, 77 and >100% after 5, 15 and 30 days, respectively. The Theoretical Oxygen Demand (ThOD) of the reference substance was calculated on the basis of its structural formula to be 2.02 mg O2/mg dodecylsufate. In conclusion, the test substance underwent 74-82% degradation within a 30 day period. Since the pass level (i.e., 60% ThOD) was reached, the substance can be considered as readily biodegradable (Richterich, 2001).