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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:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well conducted report carried out to GLP with analysis certificate and chemical analysis. Lacking information on analytical method calibration, standard curve etc. Further reliable.

Data source

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

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 302 A (Inherent Biodegradability: Modified SCAS Test)
Deviations:
yes
Remarks:
See field below (principles of method of other)
Principles of method if other than guideline:
A few minor deviations from the protocol of the SCAS test were introduced:
- the fill and draw procedure was performed only six times per week instead of daily;
- to maintain a constant pH in the SCAS unit, 1 ml of a concentrated phosphate buffer (1.6 M, pH = 7) was added six times a week;
- effluent samples were filtered using Schleicher and Schiill membranes (cellulose nitrate) with pores of 8 µm so that the test substance suspension passed through while the sludge was filtered.
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: liquid
Details on test material:
A sample of tetraethylenepentamine was received from Delamine BV on 1992.02.05. The following test substance data were submitted by the sponsor, who accepted full responsibility for the validity thereof.
- chemical name tetraethylenepentamine (TEPA)
- formula C8H23N5
- CAS-reg. no. 112-57-2
- purity 98.1%
- impurities triethylenetetramine 0.7%
- batch/lot no. 920224
- appearance liquid
- chemical stability stable under test conditions
- water solubility soluble at test concentrations
- storage at room temperature in the dark

The concentrations cited in this report are expressed in terms of the as-received technical product.

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
other: Secondary activated sludge and primary settled sewage
Details on inoculum:
Secondary activated sludge (1992.03.27) and primary settled sewage were collected from the WWTP Nieuwgraaf in Duiven. The WWTP Nieuwgraaf is an activated sludge plant treating predominantly domestic sewage. The primary settled sewage was collected weekly and stored at -20°C until required \
(minor deviation from the Guidelines). 150 ml of secondary activated sludge containing approximately 2 g suspended solids (DW) per litre was used
as an inoculum for each unit.
Duration of test (contact time):
84 d
Initial test substance concentration
Initial conc.:
33.3 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
DOC removal
Remarks:
(NPOC analysis)
Details on study design:
The SCAS test was performed according to the EEC, OECD and ISO Test Guidelines. The test was performed in diffused light at 20-25°C.
Each SCAS unit was filled with 150 ml of activated sludge and the aeration was started. After 23 hours the aeration was stopped and the sludge was allowed to settle for 45 minutes. Before settling it was necessary to clean the walls of the units to prevent the accumulation of solids above the level of the liquid. A separate brush was used for each unit to prevent crosscontamination. The tap was opened and 100 ml of the supernatant liquor withdrawn. Subsequently, a sample of primary settled sewage (99 ml) and concentrated phosphate buffer (1 ml) were added to the sludge remaining in each SCAS unit. Aeration was started anew. At this stage no test material was added and the units were fed daily with primary settled sewage.
At day 0 the individual settled sludges were mixed and 50 ml of the resulting composite sludge was added to each unit. 94 ml of primary settled sewage, 5 ml deionized water and 1 ml of concentrated phosphate buffer were added to the control unit and 94 ml of primary settled sewage, 1 ml of concentrated phosphate buffer and 5 ml of the test compound stock solution to the test unit. Aeration was started again and continued for 23 hours. The above fill and draw procedure was repeated 6 times per week throughout the test. Supernatant drawn off was analysed for non-purgeable organic carbon (NPOC). The NPOC values were used to follow the removal of the test substance for a few months. Only at the start (two weeks) of the test the NPOC in the supernatant liquor was daily determined. The next period a less frequent analysis was performed.
Reference substance
Reference substance:
other: No reference used.

Results and discussion

Preliminary study:
A Ready biodegredability test was performed prior to the SCAS test. As no biodegredation was observed the SCAS test was chosen to follow up the initial closed bottle test result.
Test performance:
No specific quality criteria reported. However Temperature and pH were sufficiently monitored and control SCAS test was run in parallel.
% Degradation
Parameter:
% degradation (DOC removal)
Value:
17
Sampling time:
84 d
Remarks on result:
other: Removal by adsorpton to sludge only
Details on results:
Test substance was not biodegraded.

BOD5 / COD results

Results with reference substance:
No reference substance reported. Control used for comparison/ calculation of removal.

Any other information on results incl. tables

% Removal

        

Time (Days)

NPOC CONTROL

NPOC TEST

REMOVAL %

-8

19.8

26.2

0

-7

21.2

21.4

0

-6

19.0

20.2

0

-5

19.5

11.2

0

4

18.8

17.4

0

2

16.8

16.5

0

1

14.0

15.1

0

0

15.0

16.4

0

1

15.5

21.9

81

2

14.2

29.7

53

3

14.1

34.5

39

4

13.2

37.9

26

6

17.8

44.8

19

7

14.1

40.3

21

8

13.5

43.6

10

9

12.6

42.6

10

10

12.7

43.1

9

11

13.5

40.5

19

13

16.4

46.9

8

14

15.1

44.9

11

15

14.0

45.4

6

17

13.4

40.8

18

20

14.1

38.4

27

22

15.5

39.1

29

24

15.3

38.1

32

27

15.5

35.5

40

29

15.0

41.9

19

31

14.1

37.3

30

34

13.8

38.6

26

36

13.8

43.8

10

38

12.3

41.8

11

41

12.7

41.1

15

43

12.5

39.6

19

45

14.9

40.3

24

48

13.9

41.6

17

50

14.1

41.2

19

52

14.4

39.8

24

55

14.6

44.4

11

57

12.4

38.3

22

59

11.3

40.3

13

63

12.4

40.5

16

64

11.8

38.5

20

66

10.6

36.5

22

69

11.3

40.9

11

71

10.8

39.9

13

73

11.2

39.4

15

76

10.5

39.5

13

78

10.1

38.0

16

80

11.0

39.5

14

83

11.5

38.6

19

84

11.9

39.0

19

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
other: Not inherently biodegradable in SCAS Test.
Conclusions:
The test was conducted with only minor modifications to the guideline. Although the study lacked some detail regarding the chemical analysis for a GLP report, this study can be considered reliable with this restriction. An analysis certificate and sufficient purity information were present. Test substance was not degraded in the SCAS Test. Some of the substance was removed by absorbtion onto sludge.
Executive summary:

Well conducted report carried out to GLP with analysis certificate and chemical analysis to the appropriate guideline. Lacking information on analytical method calibration, standard curve etc. Further reliable.