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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
26 january 2000 to 23 Fenruary 2000
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))
Deviations:
yes
Remarks:
The test substance was run in duplicate instead of in triplicate.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
Disperse Red 302

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
other: Mixture of polyvalent bacteria (activated sludge obtained from a communal wastewater treatment plant)
Details on inoculum:
- Source of inoculum/activated sludge: Mixture of polyvalent bacteria (activated sludge) collected on January 25, 2000 from the aeration tank of a
domestic sewage treatment plant, PRO RHENO Basel communal.
- pH value of the activated sludge: 6.6
- Pretreatment: The activated sludge was washed 4 times with tap water and one time with test medium. Subsequently the sludge was aerated until use. A sample of the activated sludge was taken to determine the dry weight of the suspended solids.
- Concentration of sludge: 100 mg/l suspended solids. The bacteria concentration was obtained by adding 10.4 ml of the pre-treated sludge (9.6 g/l SS) per 1000 ml test medium.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
30 mg/L
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
This method was based on the following conditions:
• Test chemicals as sole organic carbon sources
• No pre-adaptation of micro-organisms to the test chemicals
For each test series the following number of test flasks was set up:
• Test substance 2 flasks with inoculum + test medium + test substance
• Inoculum control 1 flask with inoculum + test medium
• Procedure control 2 flasks with inoculum + test medium + reference compound
• Abiotic control 1 flask with distilled water + test substance
Reference substance
Reference substance:
other: Sodium benzoate

Results and discussion

Test performance:
This method was based on the following conditions:
• test chemicals as sole organic carbon sources
• no pre-adaptation of micro-organisms to the test chemicals
For each test series the following number of test flasks was set up:
• Test substance 2 flasks with inoculum + test medium + test substance
• Inoculum control 1 flask with inoculum + test medium
• Procedure control 2 flasks with inoculum + test medium + reference compound
• Abiotic control 1 flask with distilled water + test substance
The test was performed in a Voith Sapromat apparatus.
The chemicals tested were inoculated in the testing vessels with micro-organisms. During
the test period, the Biochemical Oxygen Demand was measured continuously by means
of a BOD-meter. The biodegradation was calculated on the basis of the theoretical
oxygen demand (ThOD).
The oxygen consumption was automatically measured by the test apparatus (Voith
Sapromat). The selected measuring range was x1,(250 ml test medium per flask). The
oxygen consumption was given in milligrams O2 per litre.
The pH value of all incubation flasks was measured at the beginning and at the end of
the test.
% Degradation
Parameter:
% degradation (O2 consumption)
Value:
13
Sampling time:
28 d
Details on results:
Biodegradation of FAT 93503/A:
after 7 days 10 %
after 14 days 13 %
after 28 days 13 %

BOD5 after 5 days is 100 mg/O2/g

In the abiotic control the degradation after 28 days was 0 %.

BOD5 / COD results

BOD5 / COD
Parameter:
BOD5
Value:
100 mg O2/g test mat.
Results with reference substance:
Biodegradation of the reference substance:
The concentration of the test substance was 100 mg/l.
- Biodegradation after 7 days 74 %
- Biodegradation after 14 days 88 %
- Biodegradation after 28 days 100 %

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not inherently biodegradable
Conclusions:
In conclusion, Disperse Red 302 is not inherently biodegradable. The biodegradation of Disperse Red 302 after 28 days is 13 %.
Executive summary:

The aim of this study is to determine if FAT 93503/A is inherently biodegradable or not.

This study was perfomed according to the OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II)).

The test system used for the experiment is a mixture of polyvalent bacteria (activated sludge obtained from a communal wastewater treatment).

The duration of the test was 28 days. The experiment was done in a static condition, at 25 °C, continuously stirred and in the dark.

The test volume was 250 ml and the test concentration of FAT 93503/A was 30 mg/l.

The reference substance (Sodium benzoate), was used at 100 mg/l.

The biodegradation of the reference substance is:

- Biodegradation after 7 days 74 %

- Biodegradation after 14 days 88 %

- Biodegradation after 28 days 100 %

The biodegradation of FAT 93503/A is:

- Biodegradation after 7 days 10 %

- Biodegradation after 14 days 13 %

- Biodegradation after 28 days 13 %

In conclusion, FAT 93503/A is not inherently biodegradable. (Biodegradation is < 20 %).

The BOD5 after 5 days is 100 mg O2/gr.