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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:
2000-10-19 - 2001-01-18
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The GLP-Study was performed according to an internationally accepted guideline.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2001
Report date:
2001

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Test material form:
other: solid
Details on test material:
Purity: 100%

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, adapted
Details on inoculum:
The study was performed with aerobic activated sludge from a wastewater treatment plant (ARA Ergolz II, Fullinsdorf, Switzerland) treating predominantly domestic wastewater. The sludge was washed once with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized aliquot of the final sludge suspension was weighed, thereafter dried and the ratio of wet to dry weight was calculated.
Based on this ratio, calculated amounts of wet sludge were suspended in test water to obtain a concentration equivalent to 4 g (±10%) dry material per liter. During holding, the sludge was aerated at room temperature until use. Prior to use, the sludge was diluted with test water to a concentration of 1 g per liter (dry weight basis). This diluted activated sludge was used as inoculum to give a final concentration of 30 mg dry material per liter.
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:
O2 consumption
Details on study design:
The test water was prepared according to the testing guidelines. Analytical grade salts were dissolved in purified water to obtain the following stock solutions:
a) KH2P04 8.50 g/l K2HP04 21.75 g/l Na2HP04 x 2H20 33.40 g/l NH4CI 0.50 g/l
The pH of this solution was 7.4
b) MgS04 x 7H20 22.50 g/l
c) CaCI2 x 2H20 36.40 g/l
d) FeCI3x6H20 0.25 g/l
In order to avoid having to prepare solution d) immediately before use, one drop of concentrated HCI per liter was added.
To obtain the final test water, 10 ml of stock solution a) and 1 ml each of stock solutions b) - d) were combined and made up to 1000 ml with purified water. The pH was adjusted to 7.4 with a diluted hydrochloric acid solution.
Test Concentrations
The amounts of test item were first weighed onto slides which were then transferred into the test flasks. The reference item was added via a concentrated stock solution. No emulsifiers or solvents were used. For the test item, ultrasound dispersion was employed for fifteen minutes to obtain a more or less homogeneous suspension. To each flask (with the exception of the abiotic control) activated sludge was added. Finally, the flasks were made up to a volume of 250 ml with test water.
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Parameter:
% degradation (O2 consumption)
Value:
35
Sampling time:
28 d

Any other information on results incl. tables

Time

Percentage Biodegradation

(days)

Test item

Procedure control

Toxicity

 

 

 

 

 

control

 

Flask No.

Flask No.

Flask No.

Flask No.

Flask No.

 

9

11

1

2

12

0

0

0

0

0

0

1

0

0

9

6

2

2

0

0

52

46

16

3

-

-

4             

5             

7

1

72

67

24

6

8

4

76

70

26

7

9

6

79

73

27

8

11

7

79

75

28

9

13

8

81

77

30

10

11

19

14

83

81

34

13

21

17

83

81

35

14

23

18

84

82

36

15

25

19

84

82

37

16

27

21

84

83

38

17

18

19

30

25

86

84

42

20

31

26

86

84

42

21

32

27

86

85

43

22

33

28

86

85

44

23

34

29

87

85

45

24

25

26

36

31

87

86

46

27

37

32

87

87

46

28

38

33

88

87

48

Mean (Day28)

35

87

 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable
Conclusions:
YOFCO MAS was found to be moderately biodegradable under the test conditions within 28 days. However, the pass level for ready biodegradability, i.e. a biodégradation rate of at least 60% of the ThOD in a 10-day window within the 28-day period of the test, was not reached.
Executive summary:

The test item YOFCO MAS was investigated for its ready biodegradability in a "28-Day Manometric Respirometry Test" based onEUCommission Directive 92/69 EEC, C.4-D, 1992 and OECD Guideline for Testing of Chemicals No. 301 F, 1992.

The percentbiodégradationof the test item was calculated based on the theoretical oxygen demand of 3.13 mg 02/mg test item. The theoretical oxygen demand was additionally confirmed by determination of its chemical oxygen demand which was found to be identical to the theoretical oxygen demand.

The biochemical oxygen demand (BOD) of YOFCO MAS in the test media slowly but steadily increased from Day 1 until test termination on Day 28. At the end of the exposure period, the meanbiodégradationrate of YOFCO MAS amounted to 35%. Consequently, YOFCO MAS was found to be moderately biodegradable under the test conditions within 28 days. However, the pass level for ready biodegradability, i.e.a biodégradationrate of at least 60% of the ThOD in a 10-day window within the 28-day period of the test, was not reached.

In the toxicity control, containing both YOFCO MAS and the reference item sodium benzoate, no inhibitory effect on thebiodégradationof the reference item was determined. Thus, YOFCO MAS had obviously no inhibitory effect on the activity of activated sludge microorganisms.

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