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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
03 September 2015 to 13 November 2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report Date:
2016

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: Liquid
Details on test material:
Name: DAILUBE IS-30
Chemical Name: 1, 3-bis (2, 4, 4-trimethylpentan-2yl) trisulfane
Use: Lubricant Additive
Molecular Formula: CH3-C(CH3)2-CH2-C(CH3)2-SSS-C(CH3)2-CH2-C(CH3)2-CH3
Molecular Weight: 322 g/mol
Appearance Pale yellow
Physical State: Liquid
Batch Number: L002
Purity: 95.4% by weight
Storage: Room temperature, in the dark
Expiry Date: 2016/8/15
Specific details on test material used for the study:
Appearance Pale yellow
Physical State: Liquid
Batch Number: L002
Purity: 95.4% by weight
Storage: Room temperature, in the dark
Expiry Date: 2016/8/15

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, industrial (adaptation not specified)
Details on inoculum:
A sample of activated sludge was obtained from a sewage treatment works, which treats predominantly domestic waste. At the time of collection, the
sludge was sieved (1 mm2) then transported to the laboratory and aerated until required.

The concentration of suspended solids in a blended and homogenous sample was determined before the start of the test. Aliquots (10 mL) of the sludge were filtered through dried and pre-weighed Whatman GF/C filters in triplicate, which were then dried again at approximately 105°C for one hour, allowed to cool in a desiccator and reweighed. The mixed liquor suspended solids (MLSS) content of the sludge was then determined and the volume required to give a solids level of 30 mg/L in test cultures was calculated.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
50 mg/L
Based on:
other: oxygen demand
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
The parameter determined in this test is the cumulative amount of oxygen consumed by mixtures containing DAILUBE IS-30, mineral salts medium, and an inoculum of activated sludge after 28 days of incubation at temperatures nominally in the range 22 ± 2 °C.
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

Test performance:
The blank-corrected oxygen demanded by the culture containing the reference substance had achieved 16.46 mg O2/500 mL or 66% of the ThOD (25 mg O2/500 mL) after 3 days of incubation. In the presence of the test item, degradation of sodium benzoate had achieved 60% by Day 3. Cumulative levels of oxygen consumption by the controls after 28 days (17.38 and 21.13 mg O2/500 mL, equivalent to 34.76 and 42.26 mg O2/L) were within the guideline maximum of 60 mg O2/L. These results confirm that the test item was not inhibitory to the activity of the microbial inoculum and that the test was valid.
% Degradation
Key result
Parameter:
% degradation (O2 consumption)
Value:
9
Sampling time:
28 d
Details on results:
Mean oxygen consumption in mixtures containing the test item was equivalent to 9% of the theoretical value (25 mg O2/500 mL) at the end of the test (Day 28).
The pH of test mixtures ranged between 7.40 and 7.47 at the start of the test and 7.39 and 7.55 at the end.
The temperature of the water bath ranged from 21.4 to 22.7°C.

BOD5 / COD results

Results with reference substance:
Sodium benzoate: C7H5O2Na MW = 144 ThOD: 1.67 mg O2/mg

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
other: Not readily
Conclusions:
Mean oxygen consumption in mixtures containing the test item was equivalent to 9% of the theoretical value (25 mg O2/500 mL) at the end of the test (Day 28).
Substances are considered to be readily biodegradable in this type of test if oxygen consumption is equal to or greater than 60% of the ThOD of the test mixtures within ten days of the consumption achieving 10%. Therefore, test item was not considered to be readily biodegradable under the conditions of this test.