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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:
April 08 - 30, 2010
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Qualifier:
according to
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
The study was performer using aerobic activated sludge from AMIACQUE (Milano) wastewater treatment plant treating civil wastewater. The sludge was washed by centrifugation and the supernatant liquid phase decanted. A homogenized aliquot of the final sludge suspension was weighted, thereafter dried and the ratio of wet to dry weight was calculated as 4.8%.
Based on this ratio, calculated amounts of wet sludge were suspended in the test water to get a concentration equivalent to 3 g dry material/L. During holding, the sludge was aerated at room temperature in dark conditions. Before using, the sludge inoculums was diluted with test water to obtain a final concentration of 15 mg/L (dry weight).
Duration of test (contact time):
21 d
Initial test substance concentration
Initial conc.:
100 mg/L
Based on:
test mat.
Details on study design:
The assay on test item has been run in parallel with a ready biodegradable reference item, i.e. sodium benzoate, the inoculums control, the abiotic control containing the test item and a sterilizing agent (Hg2Cl2) and the toxicity control, containing test item, reference compound and inoculum.
BOD flasks of 500 mL capacity, equipped with pressure sensors fitted on the bottle mouth, have been used as test units.
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
21 d
Details on results:
The test item is considered to be stable at the test conditions for a time corresponding to the exposure time (21 days). Therefore, all reported results are related to the nominal concentration of the test item.
The ThODNH3 values were calculated to be equal to 1.67 mg O2/mg for reference item and 1.38 mg O2/mg for test item.
The oxygen consumption due to nitrification was measured at the begging and at the end of the test and the absence of nitrification was assessed.

The test complies with the validity criteria since the mean oxygen uptake in the inoculum control at the end of test period was 6.5 mg O2/L and the difference between duplicate values of test item degradation at the end of the test period (21 days) was 1.1%. Moreover, the reference item reached the biodegradation pass level (60%) on the fourth day (62.3%).

The test item did not show any inhibitory effects on the microorganism activity at the tested concentration as demonstrated by the 25% of biodegradation exceeded in the toxicity control already at the third day of test period (27.9%).

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not inherently biodegradable
Conclusions:
The test item has showed to be ready biodegradable under the conditions applied in a Manometric Respirometry test, having reached 98.6 % of biodegradation at the end of the 10 days windows, where the pass level is set at 60%.
Moreover, the test item did not show any inhibitory effects on the microorganism activity at the tested concentration as demonstrated by the 25% of biodegradation exceeded in the toxicity control already at the third day of test period.