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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Administrative data

Endpoint:
biodegradation in water: sewage treatment simulation testing
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2009-04-17 to 2009-06-11
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: according OECD 303A Guideline and GLP
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 303 A (Simulation Test - Aerobic Sewage Treatment. A: Activated Sludge Units)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: compact
Radiolabelling:
no

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge from the sewage plant at Hildesheim is well suited as it comprises mostly municipal sewage and hardly industrial chemical waste (industrial chemical waste: 30 - 33 %, referring to BOD).- Preparation of inoculum for exposure: The activated sludge was maintained in an aerobic condition by aeration at room temperature until it was used. Calculated starting concentration of dry matter was about 3 g/L.
Duration of test (contact time):
52 d
Initial test substance concentration
Initial conc.:
300 µg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
TEST CONDITIONS- Volume of test solution/treatment: Cstock = 3 g/L in methanol, freshly prepared at least every 7 days. Dosed at a constant rate of 0.05 L/h, corresponding to 41 µg C20-fraction of C20/22-ATQ trocken/L and 243 µg C22-fraction of C20/22-ATQ trocken/L- Composition of medium: Organic medium: Mixture of domestic sewage and synthetic sewage with 100 mg C/L- Additional substrate: Synthetic sewage was prepared according to OECD 303 A and used for DOC adjustment of domestic sewage if necessary. - Test temperature: 20 - 25 °C- pH: 7.5 +/- 0.5 (no adjustments were made)- pH adjusted: no - Suspended solids concentration: Initial dry weight content: 3.0 +/- 0.5 g/L- Continuous darkness: Low light conditions TEST SYSTEM- Apparatus: Activated sludge units consisting of an aeration vessel (3L) and a separator (2.5 L)- Number of culture flasks/concentration: 1- Method used to create aerobic conditions: continuous aeration- Measuring equipment:Oxygen, pH-value, Multi 340 (WTW) TemperaturePumpsMembrane piston pumps ProMinent® gamma/ 4-W(PROMINENT DOSIERTECHNIK GMBH, Heidelberg)Precision syringe pumps, KD SCIENTIFIC and HARVARDAPPARATUSAerationMembrane pump MP500 (BEHR LABOR-TECHNIK)DOCMulti N/C 3000 ANALYTIK JENA AG- Test performed in closed vessels due to significant volatility of test substance: No- Test performed in open system: YesSAMPLING- Sampling frequency: Type and Frequency of Measurements (exclusive test item analysis) Parameter FrequencyInfluent volumes 3x per week Removed sludge volume Daily DOC of the effluents Weekdays during acclimatisation, daily during steady state phase DOC of the influent Every new batchOxygen concentration, temperature, pH value in the aeration vessel At least twice per weekSuspended solids Daily- Sample storage before analysis: Samples were stored at -20 +/- 2 °C before preparation and at room temperature after sample preparation, if necessary. CONTROL AND BLANK SYSTEM- Inoculum blank: An activated sludge unit with methanol treatment (without test item) was used as control.- Abiotic sterile control: No- Toxicity control: No

Results and discussion

Test performance:
The system was started with the conditions described above.•Set-up of the test units•Inoculation with activated sludge•Dosage of sewage (organic medium)•Sludge adhering to the walls of the activated sludge units was resuspended•After the system had stabilized and the removal of DOC of the sewage was efficient (> 80 %) the test item solution (control: methanol) was applied.•Sampling and measurements as given above•Calculation of ultimate biodegradation of the organic medium, elimination/adsorption and primary biodegradion of the test item•Completion of the study after a sufficient degree of elimination and the plateau was reached (> 90 %).
% Degradationopen allclose all
% Degr.:
92.2
Parameter:
other: weighted average based on content of the constituents C20 and C22 ATQ
Sampling time:
52 d
% Degr.:
96
Parameter:
other: (C20 fraction) primary biodegradation
Sampling time:
52 d
Remarks on result:
other: median of all samples
% Degr.:
91
Parameter:
other: (C22 fraction) primary biodegradation
Sampling time:
52 d
Remarks on result:
other: median of all samples
Transformation products:
not measured
Remarks:
No information available.
Evaporation of parent compound:
no
Volatile metabolites:
no
Residues:
no

Any other information on results incl. tables

Influent and Effluent Concentration and Elimination of C20-fraction
                   of C20/22-ATQ trocken (exemplarily)

Study
day

Day of
test item application

Date

Influent concentration

Effluent concentration

Elimination

[µg/L]

 [µg/L]

[%]

3

0

20.04.09

42.19

 

4

1

21.04.09

42.19

0.228

99.46

5

2

22.04.09

41.00

0.228

99.46

6

3

23.04.09

41.00

0.685

98.33

7

4

24.04.09

41.57

0.228

99.44

9

6

26.04.09

42.19

0.228

99.45

10

7

27.04.09

42.19

0.228

99.46

11

8

28.04.09

42.50

0.228

99.46

12

9

29.04.09

42.50

0.685

98.39

13

10

30.04.09

42.00

0.228

99.46

14

11

01.05.09

42.00

0.228

99.46

15

12

02.05.09

41.91

0.685

98.37

16

13

03.05.09

41.91

0.685

98.37

17

14

04.05.09

41.99

0.685

98.37

18

15

05.05.09

41.99

0.685

98.37

19

16

06.05.09

42.01

0.228

99.46

20

17

07.05.09

42.01

0.228

99.46

21

18

08.05.09

42.94

0.685

98.37

22

19

09.05.09

42.94

0.228

99.47

23

20

10.05.09

41.90

0.228

99.47

24

21

11.05.09

41.90

0.228

99.46

25

22

12.05.09

42.61

0.228

99.46

26

23

13.05.09

42.61

0.228

99.46

27

24

14.05.09

42.13

0.228

99.46

28

25

15.05.09

42.13

0.228

99.46

29

26

16.05.09

41.57

0.228

99.46

30

27

17.05.09

41.57

0.685

98.35

31

28

18.05.09

42.54

0.228

99.45

32

29

19.05.09

42.54

0.685

98.39

33

30

20.05.09

41.21

0.228

99.46

34

31

21.05.09

41.21

0.685

98.34

35

32

22.05.09

42.24

0.228

99.45

36

33

23.05.09

42.24

0.685

98.38

37

34

24.05.09

42.40

0.228

99.46

continued

Study
day

Day of
test item application

Date

Influent concentration

Effluent concentration

Elimination

[µg/L]

 [µg/L]

[%]

38

35

25.05.09

42.40

0.228

99.46

39

36

26.05.09

42.64

0.228

99.46

40

37

27.05.09

42.64

0.228

99.47

41

38

28.05.09

42.09

0.685

98.39

42

39

29.05.09

42.09

0.228

99.46

43

40

30.05.09

42.14

0.228

99.46

44

41

31.05.09

42.14

0.228

99.46

45

42

01.06.09

42.26

0.685

98.37

46

43

02.06.09

43.27

0.685

98.38

47

44

03.06.09

43.27

0.228

99.47

48

45

04.06.09

43.02

0.228

99.47

49

46

05.06.09

43.02

0.228

99.47

50

47

06.06.09

42.44

0.228

99.47

51

48

07.06.09

42.44

0.228

99.46

52

49

08.06.09

41.65

0.228

99.46

53

50

09.06.09

41.65

0.228

99.45

54

51

10.06.09

43.70

1.39#

96.66

55

52

11.06.09

0.228

99.48

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The elimination was 98.83 % for the C22 fraction and 99.11 % for the C20 fraction of the test substance C20/22 ATQ. The maximum primary biodegradation was 96 % for C20-fraction of C20/22-ATQ trocken and 91 % for C22-fraction of C20/22-ATQ trocken based on the median of all samples.
Executive summary:

The elimination and biodegradation of the test item C20/22 ATQ trocken (batch no. DEG4047322) in an activated sludge unit was determined over a test period (plateau phase) of 25 days according to OECD guideline 303 A. The study was conducted from 2009-04-17 to 2009-06-19 at the Dr.U.Noack-Laboratorien, 31157 Sarstedt, Germany . The definite exposure phase was from 2009-04-20 to 2009-06-11.

During acclimatisation the activated sludge units were inoculated with activated sludge. The DOC elimination of the organic medium reached a degradation rate > 80 % already after 2 days. The dosage of the test item was started after an acclimatisation period of 3 days.

The nominal concentration of the test item stock solution was 3 g/L. The stock solution was dosed at a constant rate of 0.05 mL/h into the activated sludge unit, resulting in a nominal influent concentration of 300 µg/L corresponding to 41 µg C20-fraction of C20/22-ATQ trocken/L and 243 µg C22-fraction of C20/22-ATQ trocken/L. The influent concentration was corrected by the C20-fraction of C20/22-ATQ trocken and C22-fraction of C20/22-ATQ trocken concentration of the organic medium.

Specific analysis of C20/22 ATQ trocken was carried out via LC-MS/MS. The concentrations of C20-fraction of C20/22-ATQ trocken and C22-fraction of C20/22-ATQ trocken in the influent (organic medium and stock solution), effluent and activated sludge were determined. The LOQ for the organic medium was 30 µg/L C20/22 ATQ trocken corresponding to 4.11 µg/L C20-fraction of C20/22-ATQ trocken and 24.3 µg/L C22-fraction of C20/22-ATQ trocken. For activated sludge the LOQ was 55.6 µg C20/22 ATQ trocken/g DW corresponding to 7.62 µg/g for the C20-fraction of C20/22-ATQ trocken and 45.0 µg/g for  the C22-fraction of C20/22-ATQ trocken.

The LOQ for the effluent was 15 µg/L C20/22 ATQ trocken corresponding to 2.06 µg/L C20-fraction of C20/22-ATQ trocken and 12.1 µg/L C22-fraction of C20/22-ATQ trocken. The effluent concentration was below the LOD or LOQS. The elimination was therefore calculated based on the LOD of 0.228 µg/L for C20-fraction of C20/22-ATQ trocken and 2.03 µg/L for C22-fraction of C20/22-ATQ trocken and on the LOQS of 0.685 µg/L for C20-fraction of C20/22-ATQ trocken and 4.05 µg/L for C22-fraction of C20/22-ATQ trocken.

One day after starting the application of C20/22 ATQ trocken the elimination was already > 99 % for C20-fraction of C20/22-ATQ trocken and C22-fraction of C20/22-ATQ trocken. C20/22 ATQ trocken adsorbed completely onto the activated sludge. Furthermore, primary biodegradation started directly after starting the application of C20/22 ATQ trocken. For C20-fraction of C20/22-ATQ trocken the biodegradation was > 80 % already after 6 days. The biodegradation increased consistently and during the plateau phase, a primary biodegradation of 96 % was reached (median of all samples). For C22-fraction of C20/22-ATQ trocken the primary biodegradation reached 82 % on day 15 and during the plateau phase a primary biodegradation of 91 % was reached (median of all samples). The maximum primary biodegradation was 98 % for C20-fraction of C20/22-ATQ trocken and 93 % for C22-fraction of C20/22-ATQ trocken (Table 2).

Table 1:    Statistical Evaluation of Influent Concentration and Elimination

C20-fraction of C20/22-ATQ trocken

C22-fraction of C20/22-ATQ trocken

Influent

Elimination

Influent

Elimination

[µg/L]

[%]

[µg/L]

[%]

Range measured

41.0 - 43.7

96.66 - 99.48

243.0 - 255.2

95.14 - 99.20

Median

42.2

99.46

249.2

99.18

Mean

42.2

99.11

249.2

98.83

95 % CI

42.0 - 42.4

98.94 - 99.28

248.4 - 250.0

98.65- 99.01

Number of case n

52

52

52

52

CI = Confidence Interval

Table 2:     Statistical Evaluation on the Biodegradation for C20-fraction of C20/22-ATQ
                   trocken and C22-fraction of C20/22-ATQ trocken during the Plateau Phase

Biodegradation

C20-fraction of
C20/22-ATQ trocken

C22-fraction of
C20/22-ATQ trocken

[%]

[%]

Range measured

94 - 98

87 - 93

Median

96

91

Mean

96.4

90.5

95 % CI

96.1 - 96.7

89.8 - 91.2

Number of case n

25

25

             CI = Confidence Interval

For exposure calculations a weighted biodegradation in the STP Simulation test for the C20/22 ATQ of 92.2% was assumed.

The validity criteria of the test are fulfilled according to the guideline.