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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:
06.02.2013 to 06.03.2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:
yes (incl. certificate)
Remarks:
Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Auf dem Aberg 1, 57392 Schmallenberg (Germany)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): diethyl carbonate
- Substance type: ester
- Physical state: colourless liquid
- Analytical purity: 99.94%
- Impurities (identity and concentrations): ethanol/methanol, water
- Composition of test material, percentage of components: ethanol/methanol: 0.03%, water: 0.01%
- Purity test date: 14.01.2013
- Lot/batch No.: F2012070405
- Expiration date of the lot/batch: 31.07.2014
- Storage condition of test material: test material stored dry at room temperature, well ventilated, container closed

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Fresh samples of activated sludge were collected from the sewage treatment plant Ruhrverband Kläranlage, Schmallenberg (Germany) which is mainly fed with municipal wastewater
- Laboratory culture: no
- Preparation of inoculum for exposure: The samples were not washed with mineral medium, since it was not necessary, but kept aerobic until use
- Pretreatment: no
- Concentration of sludge: 29,5 mg dry mass/L
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
100 mg/L
Based on:
test mat.
Initial conc.:
32 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: according to guideline
- Additional substrate: no
- Solubilising agent (type and concentration if used): no
- Test temperature: 22 +/- 1°C
- pH: 7.4 +/- 0.2
- pH adjusted: yes
- Aeration of dilution water: not reported
- Suspended solids concentration: 29.5 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: respirometer
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: The activated sludge was kept in aerobic conditions until use. The test suspension was aerated during the whole test
- Measuring equipment: SAPROMAT respirometer (Voith Inc.)
- Test performed in closed vessels: yes
- Details of trap for CO2: no details reported

SAMPLING: The measurement and recording of the oxygen demand was carried out continuously throughout the test.

CONTROL AND BLANK SYSTEM
- Inoculum blank: performed
- Abiotic sterile control: performed
- Toxicity control: performed
- Other: procedural/functional control with the reference substance sodium benzoate performed
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
100
St. dev.:
1.4
Sampling time:
28 d
Remarks on result:
other: test substance concentration: 32 mg/L
Parameter:
% degradation (O2 consumption)
Value:
81
St. dev.:
0.4
Sampling time:
28 d
Remarks on result:
other: test substance concentration: 100 mg/L

BOD5 / COD results

Results with reference substance:
The reference substance sodium benzoate was biodegraded by 88% after 14 d and the requirement of the guideline (>60% biodegradation after 14 d of incubation) is fulfilled.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The ready biodegradation of the diethyl carbonate was investigated in a study conducted according to OECD Guideline 301 F. The test item proved to be readily biodegradable and fulfilling the 10-d-window criterion (100% and 81% biodegradation after 28 d of incubation at test substance concentrations of 32 and 100 mg/L, respectively).
Executive summary:

The ready biodegradation of the diethyl carbonate was investigated in a study conducted according to OECD Guideline 301 F over a period of 28 days and using activated sludge as inoculum collected from a sewage treatment which is mainly fed with municipal wastewater. The biodegradation rate was determined by measurement of oxygen consumption. Inoculum blank, procedural/functional control with the reference substance sodium benzoate, and toxicity control using 100 mg/L test item and 100 mg/L reference compound were performed.

 

This study is regarded as reliable without restriction and satisfies the guideline requirements for ready biodegradation.

The test item proved to be readily biodegradable and fulfilling the 10-d-window criterion (100% and 81% biodegradation after 28 d of incubation at test substance concentrations of 32 and 100 mg/L, respectively). The functional control reached the pass level > 60% after 14 d. In the toxicity control containing both test and reference item 72% biodegradation based on oxygen consumption occurred within 14 d thus indicating that the test item was not inhibitory at the concentration tested.