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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:
From 06 April, 2016 to 02 June, 2016
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 guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
- Appearance: Colorless liquid
- Purity: 94.9% (An amount of the test substance was corrected for its purity in the biodegradation study.)
- Lot number: 16-1-1

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
On-site sludge sampling was carried out at 10 locations in Japan (samples were from surface water and surface soil of rivers, lakes, and inland sea; return sludge from sewage plants). Activated sludge, which was prepared and controlled in the test laboratory according to the test guideline, was used in this study (sampling period: January, 2016, initiation date of use: February 19, 2016). The activated sludge, which was cultivated for 18 hours after the addition of the synthetic sewage, was used. The synthetic sewage was prepared according to the following method; glucose, peptone, and potassium dihydrogenphosphate were dissolved in purified water, and the pH of the solution was adjusted to 7.0±1.0. The concentration of suspended solid in the activated sludge was 3410 mg/L.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
100 mg/L
Based on:
test mat.
Remarks:
100 mg/L as the test substance, 106 mg/L as the test material.
Parameter followed for biodegradation estimationopen allclose all
Parameter followed for biodegradation estimation:
O2 consumption
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
Test conditions
- Concentration of test substance: 100 mg/L
- Concentration of activated sludge: 30 mg/L (as concentration of suspended solid)
- Volume of test solution: 300 mL
- Incubation temperature: 25±1°C
- Composition of medium: Mineral nutrient solution (pH 7.0) according to the OECD Guideline 301CTest system
- Test solution with purified water + test substance: n=1
- Test solution with medium + test substance + activated sludge: n=3
- Test solution with medium + activated sludge: n=1
- Test solution with medium + aniline + activated sludge: n=1
Reference substance
Reference substance:
aniline
Remarks:
Purity: 99.9%, 100 mg/L in the test solution

Results and discussion

% Degradationopen allclose all
Key result
Parameter:
% degradation (O2 consumption)
Value:
99
Sampling time:
28 d
Key result
Parameter:
% degradation (test mat. analysis)
Value:
100
Sampling time:
28 d
Details on results:
Percentage biodegradation on 28 days
- O2 consumption: 89%, 104% and 105 %
- Test mat. analysis: 100%, 100% and 100 %
Percentage residue of test substance on 28 days
- Test solution with purified water + test substance: 100%
- Test solution with medium + test substance + activated sludge: 0%, 0% and 0%

BOD5 / COD results

Results with reference substance:
Percentages of biodegradation of aniline were 85% on 7 days and 91% on 14 days. These values met the validity criteria of the test (>40% on 7 days and >65% on 14 days).

Any other information on results incl. tables

The validity criteria of the tests and the values in this test are shown in the following table. This test was valid because all the values in this test met the criteria.

Table 1. Validity of test conditions

 Value in test

Value of criterion

Difference between extremes of replicate values of percentage biodegradation

Percentage biodegradation by BOD

16%

<20%

Percentage biodegradation by GC

0%

<20%

Percentage biodegradation of aniline by BOD

On 7 days

85%

>40%

On 14 days  91% >65%
BOD value of control blank

On 28 days

54 mg/L

≤60 mg/L

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test item was completely biodegraded under the test conditions of this study.
Executive summary:

The average percentage biodegradation by BOD and that of the test substance by GC were 99% and 100%, respectively. In addition, no peaks corresponding to converted products were detected on the GC chromatograms, and growth of the sludge was observed in the test solutions at the end of the incubation.

From the above-mentioned results, it was concluded that the test item was completely biodegraded under the test conditions of this study.