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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:
1992
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992
Report Date:
1992

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
EU Method C.6 (Degradation: Chemical Oxygen Demand)
Deviations:
not specified
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
not specified
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, industrial (adaptation not specified)
Details on inoculum:
Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): effluent of a domestic sewage treatment plant located in Hennef, Germany
- Water filtered: yes
- Type and size of filter used, if any: inoculum was filtered through a coarse folded filter and the first 200 mL discarded
Duration of test (contact time):
27 d
Initial test substance concentrationopen allclose all
Initial conc.:
2.49 mg/L
Based on:
test mat.
Initial conc.:
3.91 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: filtered sewage
- Test temperature: 20 +/- 1 °C
- pH: not stated
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 300 mL flasks
- Number of culture flasks/concentration: 2
- Measuring equipment: dissolved oxygen content was determined using the oxygen measuring apparatus Syland Temp-O2-Mat 4002


SAMPLING
- Sampling frequency: day 5, 15 and 27
- Sampling method: oxygen content was measured within the test flasks


CONTROL AND BLANK SYSTEM
- Inoculum blank: the oxygen content of the mineral nutrient solution without inoculum and without test substance as well as without test substance but with inoculum was tested on day 0, 5, 15 and 27
- other: to test the inhibition effect of the test substance to the inoculum, an additional test run was prepared containing 3.91 mg test substance/L and 5.0 mg sodium acetate/L


STATISTICAL METHODS: no statistics were performed
Reference substance
Reference substance:
acetic acid, sodium salt
Remarks:
5 mg/L and 10 mg/L

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
< 5
Sampling time:
5 d
Remarks on result:
other: mean of 2 test concentrations
Parameter:
% degradation (O2 consumption)
Value:
< 5
Sampling time:
15 d
Remarks on result:
other: mean of 2 test concentrations
Parameter:
% degradation (O2 consumption)
Value:
< 5
Sampling time:
27 d
Remarks on result:
other: mean of two test concentrations
Details on results:
The biological oxygen demand was <5% of the chemical oxygen demand in both test concentrations at all sampling dates.

Sodium acetate in the inhibition test (medium contained test substance as well as reference substance) was degraded by 80% at day 27 which indicates that the test concentration did not have inhibitory effects on the inoculum.

BOD5 / COD results

Results with reference substance:
The biodegradation of sodium acetate was >95% .

Any other information on results incl. tables

TEST SUBSTANCE

Results of oxygen measurements during the test

 

 

Oxygen content [mg O2/L ]

Test duration [d]

0

5

15

27

Medium without test substance, without inoculum

1

2

mean

8.77

8.86

8.82

8.73

8.80

8.77

8.79

8.51

8.65

8.50

8.48

8.49

Medium without test substance, with inoculum

1

2

mean

8.72

8.80

8.76

8.67

8.74

8.71

8.63

8.70

8.67

8.55

8.42

8.49

Medium with 2.49 mg test substance/L and inoculum

1

2

mean

8.91

8.95

8.93

8.72

8.73

8.73

8.68

8.71

8.70

8.43

8.56

8.50

Medium with 3.91 mg test substance/L and inoculum

1

2

mean

8.92

8.91

8.92

8.67

8.70

8.69

8.58

8.63

8.61

8.40

8.27

8.34

Decrease in oxygen content of test medium

Test substance concentration [mg/L]

Biological oxygen demand [mg/L]

Day 5

Day 15

Day 27

2.49

-0.02

-0.03

-0.01

3.91

0.02

0.06

0.15

 

Biodegradation of test substance

Test substance concentration [mg/L]

%BOD of COD [mg/L]

Day 5

Day 15

Day 27

2.49

<5

<5

<5

3.91

<5

<5

<5

Mean

<5

<5

<5

COD: Chemical oxygen demand of test substance (2.26 mg O2/mg)

REFERENCE SUBSTANCE (SODIUM ACETATE)

Results of oxygen measurements during the test

 

 

Oxygen content [mg O2/L ]

Test duration [d]

0

5

15

27

Medium without test substance, without inoculum

1

2

mean

8.77

8.86

8.82

8.73

8.80

8.77

8.79

8.51

8.65

8.50

8.48

8.49

Medium without test substance, with inoculum

1

2

mean

8.72

8.80

8.76

8.67

8.74

8.71

8.63

8.70

8.67

8.55

8.42

8.49

Medium with 5.0 mg reference substance/L and inoculum

1

2

mean

8.83

8.80

8.82

5.87

5.85

5.86

5.48

5.49

5.49

3.90

4.05

3.98

Medium with 10.0 mg reference substance/L and inoculum

1

2

mean

8.84

8.82

8.83

2.90

2.88

2.89

2.41

2.32

2.37

0.95

0.87

0.91

 

Decrease in oxygen content of test medium

Reference substance concentration [mg/L]

Biological oxygen demand [mg/L]

Day 5

Day 15

Day 27

5.0

2.85

3.18

4.51

10.0

5.82

6.30

7.58

 

Biodegradation of reference substance

Reference substance concentration [mg/L]

%BOD of ThOD [mg/L]

Day 5

Day 15

Day 27

5.0

73

81

>95

10.0

75

81

>95

Mean

74

81

>95

ThOD: theoretical oxygen demand (0.78 mg O2/mg for sodium acetate

The test is considered to be valid as validity criteria were fulfilled (more than 60% of the reference substance was degraded after 27 days; the oxygen consumption in the test medium (blank control) did not exceed 0.4 mg/L and was < 0.6 mg/L in the inoculum control after 14 and 27 d).

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Under test conditions no biodegradation observed