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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:
4.2.-5.3.2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study was carried out in accordance with internationally valid GLP principles.

Data source

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

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): 3,4-Ethylenedioxythiophene
- Comercial name. EDOT
- Substance type: pure organic substance
- Physical state: liquid near colourless to pale yellow
- Analytical purity: > 99%
- Lot/batch No.: 091201
- Expiration date of the lot/batch: 21.1.2011
- Storage condition of test material: Keep in dark at room temperature. Stored in amber glass bottles under the argon atmosphere. Minimalize time for handling with substance without protective argon atmosphere as possible. Maximal time without protective atmosphere is 30 min.

Study design

Oxygen conditions:
anaerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: a mixed population of microorganisms obtained from the secondary effluent of the wastewater treatment plant of Pardubice processing predominantly municipal sewage.
- Preparation of inoculum for exposure: The fresh collected wastewater was filtered through paper filter. COD was determined and wastewater was aerated till using.

Duration of test (contact time):
0 - 28 d
Initial test substance concentrationopen allclose all
Initial conc.:
2.1 mg/L
Based on:
test mat.
Initial conc.:
3.4 mg/L
Based on:
COD
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: preparation of mineral medium in accordance to Method C.4E - Closed Bottle Test, Council Regulation (EC) No. 440/2008, published in O. J. L 142, 2008.
- Test temperature: 20 +/- 1°C
- pH: 7.4
- pH adjusted: no
- Illumination: no illumination, in the darkness


TEST SYSTEM
- Series of bottles for the test:
- 2 x 9 bottles with test substance and inoculated medium
- 2 x 9 bottles with reference substance and inoculated medium for the check of inoculum activity
- 2 x 5 bottles with test and reference substance mixture and inoculated medium for the toxicity test
- 2 x 9 bottles with inoculated medium only for the blank determination

- Method used to create anaerobic conditions: completely full closed bottles
- Measuring equipment: equipment for the determination of dissolved oxygen


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, the inoculated mineral medium
- Toxicity control: yes, the test and reference substance mixture

MEASUREMENT:
- analysis for dissolved oxygen by the Winkler method at the zero-time, 3rd, 7th, 10th, 14th, 17th, 21st, 24th and 28th day.
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

Test performance:
The results of biological degradation are related to experimentally determined COD values of test and reference substance at the beginning of the test.
The test substance had sufficient solubility in used mineral medium. The dosage from the stock solution was carried out.
In parallel to the main test the toxicity test was performed. The test substance was not inhibiting for the used inoculum.
% Degradation
Parameter:
% degradation (O2 consumption)
Value:
7.6
Sampling time:
28 d

BOD5 / COD results

BOD5 / CODopen allclose all
Parameter:
BOD5
Value:
0.02 other: mg/mg
Parameter:
COD
Value:
1.62 other: mg/mg
Results with reference substance:
COD of reference substance: 1.642 mg/mg, biodegradation 71.6% after 28 days.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
In this 28-day study of ready biodegradability the degradation of 7.6 % of the test substance, 3,4-Ethylenedioxythiophene, was attained in the end of study.