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Environmental fate & pathways

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:
06.02.-10.03.2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Details on inoculum:
INOCULUMThe inoculum contained a mixed population of microorganisms obtained from the secondary effluent of the waste water treatment plant of Pardubice processing predominantly municipal sewage.PREPARATION OF INOCULUMThe fresh collected waste water was filtered through paper filter. COD was determined and waste water was aerated till using.Justification of the test systemThe inoculum preparation is in conformity with the recommendations of the test guideline.
Duration of test (contact time):
28 d
Initial conc.:
141 mg/L
Based on:
COD
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS- Inoculated medium: The volume of waste water for the inoculation of mineral medium was chosen 2.2 mL per 1 L of medium (COD of waste water: 47 mg·L-1). 30 L aerated mineral medium was prepared for the test and before the beginning of the test it was inoculated with 66 mL of modified waste water. The pH value of medium: 7.4.- Test temperature: 20+/-1 °C- pH of medium: 7.4- pH adjusted: no- Illummination: in the darkTEST SYSTEMTest substance series: 2 x 9 bottles with test substance and inoculumReference substance series: 2 x 9 bottles with reference substance and inoculum Blank series:2 x 9 bottles with inoculated medium onlyToxicity test series: 2 x 5 bottles with test substance, reference substance and inoculum Series for nitrification determination:1 x 9 bottles with test substance and inoculumCONTROL AND BLANK SYSTEM- Inoculum blank: yes, the inoculated mineral medium- Toxicity control: yes, the test and reference substance mixtureMeasurementThe first two bottles from each series were immediately submitted to analysis for dissolved oxygen (zero-time) and other bottles were placed in the thermostat. On the 3rd, 7th, 10th, 14th, 17th, 21st, 24th and 28th day of the test, two bottles (parallel replicate) from the test substance series, from the reference substance series and from the blank series were taken off and the same determinations were performed.On the 3rd, 7th, 10th, 14th day of the test, two bottles from the toxicity test series were taken off and the same determination was performed.The analysis of dissolved oxygen was performed electrochemically using oximeter device (oximeter WTW OXI 730).On the 3rd, 7th, 10th, 14th, 17th, 21st, 24th and 28th day of the test, one bottle from the seriesfor nitrification determination was taken off and the determinations of nitrite-N concentration was carried out of spectrometric methods.
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
28 d
Key result
Parameter:
COD
Value:
1.399 other: mg/mg
Key result
Parameter:
BOD5
Value:
0.129 other: mg/mg
Results with reference substance:
COD of reference substance 1.643 mg.mg-1 and 73.9 %
Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
In this 28-day study of ready biodegradability a degradation of 0.0 % of the test substance Acid Yellow 25 was attained in the end of study.
Executive summary:

The test substance, Acid Yellow 25,was tested forthe ready biological degradability in Closed Bottle Test.

Test performance

The test was performed according to:

Method C.4E - Closed Bottle Test, Council Regulation (EC) No. 440/2008, published in O.J.L 142, 2008.

 

The results of biological degradation are related to experimentally determined COD values of the test and reference substance at the beginning of the test.

The test substance was sufficiently soluble in used mineral medium so the dosage from the stock solution was carried out.

Sodium benzoate was used as the reference substance. The dosage was carried out from the stock solution.

Specific COD of the test substance in medium:                   1.399 mg·mg-1

Specific COD of the reference substance in medium:         1.643 mg·mg-1

In parallel to the main test the toxicity test was performed.

Based on the test substance contains nitrogen in the chemical composition, the oxidized nitrogen forms were determined and the correction for nitrification was carried out.

The test was performed at temperature of 20 ± 1 °C with the pH values of solutions 7 – 8 at the beginning of the test.

 

Validity of the test

The prescribed validity criteria in the test were fulfilled.

The test substance was not inhibiting for the used inoculum.

Since all criteria of acceptability were met, this study is considered to be valid.

 

Test results

In this28-day study of ready biological degradabilitythe degradation of 0 % of the test substance,Acid Yellow 25,was attained in the end of study.

Description of key information

The test was performed according to: Method C.4E - Closed Bottle Test, Council Regulation (EC) No. 440/2008, published in O.J.L 142, 2008.

Only one study is available.

GLP study.

Klimish score 1.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information