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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:
27th June 2007 July 25th 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of relevant results.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report date:
2007

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: Japanese MITI guideline
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Lot number: MB-1
Purity: 96.3%
Appearance: Dark blue powder
Stability: Stable
Storage conditions: Dark storage place at room temperature

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):
On-site sampling carried out at 10 locations in Japan. Return sludge was collected from sewage plants and surface water and surface soil in contact with the atmosphere was collected from rivers, lakes and the sea.

- Preparation of activated sludge; The filtrate (5 l) of the supernatent of the activated sludge cultivated for abut 3 months was mixed with the mixed filtrate ( 5 l) of the supernatent of a sludge collected newly at each location. The mixed filtrate (10 l) was aerated after the pH value of the mixture was adjusted to 7.0 +/- 1.0.

- Cultivation: Approximately 30 minutes after ceasing aeration of the sludge mixture, supernatent corresponding to about 1/3 of the whole volume was removed. Dechlorinated water was added to te remaining portion so that the total volume reached 10 litres. This mixture was aerated for 30 minutes or more, then a pre-determined amount of synthetic sewage was added to the mixture so that the concentration of the synthetic sludge was 0.1% in the volume of dechlorinated water added. This procedure was repeated once every day. cultivation was carried out at 25 +/- 2°C.

- Synthetic sludge: Glucose, peptone and potassium dihydrogenphosphate were dissolved in purified water to obtain 50 g/l of the solution for each component. The pH of the solution was adjusted to 7.0 +/- 1.0 woth sodium hydroxide.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
other: Biochemical oxygen demand - BOD
Details on study design:
TEST CONDITIONS
- Composition of medium: Each 3 ml of solutions of A, B C and D were made up to 1000 ml with purified water.
- Additional substrate: not applicable
- Solubilising agent (type and concentration if used): not applicable
- Test temperature: 25 +/- 1°C
- pH: 7
- pH adjusted: yes
- CEC (meq/100 g): not stated in report
- Suspended solids concentration: 3600 mg/l in the activated sludge
- Continuous darkness: not stated in report

TEST SYSTEM
- Culturing apparatus: closed system oxygen consumption measuring apparatus
- Number of culture flasks/concentration: three
- Method used to create aerobic conditions: not stated in report
- Method used to create anaerobic conditions: not applicable
- Measuring equipment: closed system oxygen consumption measuring apparatus
- Test performed in closed vessels: yes
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: not appicable

SAMPLING
- Sampling frequency: Day 7, 14, 21 and 28
- Sampling method: not stated in report
- Sterility check if applicable: not applicable
- Sample storage before analysis: not applicable

CONTROL AND BLANK SYSTEM
Control blank: In one test vessel, nothing was added to the basal culture medium (the volume was less than 300 ml by the volume (2.50 ml) of activated sludge inoculated.

Reference substance
Reference substance:
aniline

Results and discussion

Preliminary study:
No preliminary study described in report.
Test performance:
The biodegradability test was judged valid since the measurement results fulfilled all the validity criteria of the guideline.
% Degradation
Parameter:
other: biochemical oxygen demand - BOD
Value:
0
Sampling time:
28 d
Details on results:
Points of degradation plot (test substance):
0 % degradation after 7 d
0 % degradation after 14 d
0 % degradation after 21 d
0 % degradation after 28 d

BOD5 / COD results

BOD5 / COD
Parameter:
BOD5
Value:
1 other: mg C/L
Results with reference substance:
Points of degradation plot (reference substance - aniline):
56 % degradation after 7 d
73 % degradation after 14 d
77 % degradation after 21 d
79 % degradation after 28 d

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
other: not readily biodegradable
Conclusions:
The average percentage biodegradation was regarded as 0% over 28 days because the calculated average value was negative.
Executive summary:

The average percentage biodegradation was regarded as 0% because the calculated average value was negative.