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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: screening test, other
Remarks:
Inherent biodegradation test
Type of information:
experimental study
Adequacy of study:
key study
Study period:
26 January 2000 to 23 February 2000.
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
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
Oxygen conditions:
aerobic
Inoculum or test system:
other: Mixture of polyvalent bacteria (Activated sludge obtained from a communal waste-water treatment plant).
Details on inoculum:
Test organism:
Strain / Inoculation: 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. The pH value of the activated sludge was 6.6.

Sludge pre-treatment: 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.

Bacteria concentration: 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 conc.:
30 mg/L
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Experimental conditions:
-Temperature: 25 °C
-Test duration: 28 days
-Lighting: darkness

Stock solution and test concentrations:
-Stock solution 2.5 g/500 ml reference substance in distilled water
-Test concentrations 100 mg/l of the reference substance (20 ml stock solution in 1000 ml test medium).

-30 mg/l of the test substance
-Because the test substance was not completely soluble in the test medium it was given directly into the test system without preparation of a stock
solution.

Directly weighing:
-7.4 mg test substance/ 250 ml test medium in flask 7
-7.4 mg test substance/ 250 ml test medium in flask 8
-7.6 mg test substance/ 250 ml test medium in flask 9

Test medium:
The mineral salts for each of the following stock solutions were dissolved in 1 litre of distilled water.

Stock solution A:
-8.5 g of potassium acid phosphate, 21.75 g of di-potassium hydrogen phosphate, 22.18 g of di-sodium hydrogenphosphate dihydrate and 1.7 g of ammonium chloride. The pH value of this solution was 7.2.

Stock solution B:
36.4 g of calcium chloride dihydrate

Stock solution C
22.5 g of magnesium sulfate heptahydrate

Stock solution D
0.25 g of ferric chloride hexahydrate

3 ml of each of the following stock solutions were added per 1 litre distilled water to form the test medium.
Reference substance:
other: Sodium benzoate
Key result
Parameter:
% degradation (O2 consumption)
Value:
21
Sampling time:
28 d
Key result
Parameter:
BOD5
Value:
0 mg O2/g test mat.
Results with reference substance:
Biodegradation of the reference substance after 7 days 74 %.
-after 14 days 88 %
-after 28 days 100 %

-Degradation in the abiotic control after 28 days 0 %

Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable
Conclusions:
In conclusion, on the basis of this present study, FAT 93504/A was found to be biodegradable at 21 % (primary biodegradation) after an incubation time of 28 days.
Executive summary:

The aims of this study are to determine the inherent biodegradability and the BOD5 of FAT 93504/According to the OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II)).

A reference substance was used during this experiment in same condition as the test substance.

The duration of the test was 28 days.

The experiment was done at 25 °C in a static condition.

The test volume was 250 ml and it was continuously stirred in the darkness.

Test concentration of the test substance was 30 mg/l and the concentration of the reference substance was 100 mg/l.

The biodegradation of the test substance after 28 days is 21 % (primary biodegradation) and the BOD5 after 5 days is 0 mg O2/g.

The biodegradation of sodium benzoate, (reference substance), after 14 days is 88 %.

Description of key information

The test substance can be considered to be inherently biodegradable.

The biodegradation od the test substance after 28 days is 21 %.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information

A study was performed to determine the inherent biodegradability and the BOD5 of FAT 93504/A according to the OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II)).

The biodegradation of the test substance after 28 days is 21 % and the BOD5 after 5 days is 0 mg O2/g.