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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
23 November 2010 to 01 March 2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
- Names of test material (as cited in study report): Aldehyde C9 nonylic food grade; nonanal
- Substance type: Colourless to pale yellow liquid
- Physical state: Liquid
- Lot No: VE00120901
- Expiration date of the lot: 2011-10-14
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage was used.
- Storage conditions: Aerobic
- Storage length: The sludge was used on the same day it was collected.
- Preparation of inoculum for exposure: The sludge was collected in the morning, washed three times in the mineral medium (by centrifuging at 1000g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.
- Concentration of sludge: Dry weight of suspended solids: 4.37 g/L
- Water filtered: No data
Duration of test (contact time):
61 d
Initial conc.:
20.2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium:
Solution A:
- KH2PO4: 8.5 g
- K2HPO4: 21.75 g
- Na2HPO4.2H2O: 33.4 g
- NH4Cl: 0.5 g
dissolved in water and made up to 1 L.
Solution B:
- CaCl2: 27.5 g
dissolved in water and made up to 1 L.
Solution C:
- MgSO4.7H2O: 22.5 g
dissolved in water and made up to 1 L.
Solution D:
- FeCl3.6H2O: 0.25 g
- HCl conc.: 1 drop
dissolved in water and made up to 1 L.
The mineral medium was prepared by mixing 50 mL of solution A and 2000 mL deionised water, adding 5 mL of each of the solutions B, C and D and making up to 5 L with deionised water.
- Test temperature: 22.2 - 23.0 °C
- pH: Initial: 7.6; Final: 7.49 - 7.50
- pH adjusted: yes (to 7.4 ± 0.2 with phosphoric acid or potassium hydroxide as appropriate)
- Aeration of dilution water: No data
- Suspended solids concentration: Dry weight: 4.37 g/L, diluted to 1.53 g/L
- Continuous darkness: No data
- Other: The water used during the study was deionised water containing less than 10 mg/L dissolved organic carbon.

TEST SYSTEM
- Culturing apparatus: Test flasks of the Oxitop were used and filled with 250 mL of the mineral medium (flasks containing the reference substance: 100 mL). Samples of test or reference substance were then added, followed by the suspended sludge.
- Number of culture flasks/concentration: 2 flasks
- Method used to create aerobic conditions: The flasks were continually stirred.
- Measuring equipment: The respirometer used during the study was an Oxitop Control System.
- Test performed in closed vessels: yes (the flasks were closed tightly with the measuring heads)
- Details of trap for CO2: Two sodium hydroxide pellets were placed in the quivers on top of each bottle.

SAMPLING
The oxygen consumption of each flask was recorded daily.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Abiotic sterile control: No
- Toxicity control: No

STATISTICAL METHODS: No data
Reference substance:
benzoic acid, sodium salt
Remarks:
99.0 mg/L
Test performance:
The repeatability validity criterion (not more than 20% difference between replicates) was fulfilled.
Parameter:
% degradation (O2 consumption)
Value:
83
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
87
Sampling time:
61 d
Details on results:
Aldehyde C9 Nonylic Food Grade underwent 83% biodegradation after 28 days (87% after 61 days) in the test conditions. The 10 day window was also fulfilled (23% biodegradation on day 1 and 71% on day 11).
Aldehyde C9 Nonylic Food Grade did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.
Results with reference substance:
Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days. The activity of the inoculum was thus verified (validity criterion).

Table 1:O2uptake for Aldehyde C9 Nonylic Food Grade (mg/L O2adjusted to nominal concentrations)

-

Days

1

11

14

21

28

42

61

O2uptake of sludge (inoculum blank)

1a

B1

5.4

26.9

29.6

32.3

36.3

44.4

55.2

2a

B2

5.4

28.3

31.0

35.0

37.7

41.7

48.5

Mean

B

5.4

27.6

30.3

33.7

37.0

43.1

51.9

O2uptake of Test Substance + sludge

3a

C1

20.1

71.0

75.0

81.7

87.1

93.8

100.6

4a

C2

17.4

66.8

72.2

78.9

84.2

95.0

104.4

O2uptake of Test Substance

-

C1-B

14.7

43.4

44.7

48.1

50.1

50.8

48.8

-

C2-B

12.0

39.2

41.9

45.2

47.2

51.9

52.5

% biodegradation of test substance

-

D1

25

74

77

82

86

87

84

-

D2

20

67

72

77

81

89

90

Mean

D

23

71

74

80

83

88

87

Calculations:

B1, B2, C1, C2: experimental O2uptake values

B = (B1+B2)/2

D1 = 100(C1-B)/ThOD*[S]

D2 = 100(C2-B)/ThOD*[S]

D = (D1+D2)/2

ThOD: 2.92 mg O2/mg

[S]: Initial test substance concentration (mg/L)

 

 

Table 2:O2uptake for sodium benzoate (mg/L O2adjusted to nominal concentrations)

-

Days

5

7

14

21

28

O2uptake of sludge (inoculum blank)

1a

B1

18.8

22.9

29.6

32.3

36.3

2a

B2

20.2

22.9

31.0

35.0

37.7

Mean

B

19.5

22.9

30.3

33.7

37.0

O2uptake of Reference Substance + sludge

17a

A1

136.1

152.3

172.4

178.4

188.5

18a

A2

*

*

*

*

*

O2uptake of Reference Substance

-

A1-B

116.6

129.4

142.1

144.8

151.5

-

A2-B

*

*

*

*

*

% biodegradation of reference substance

-

D1

70

78

85

87

91

-

D2

*

*

*

*

*

Mean

D

70

78

85

87

91

Calculations:

B1, B2, A1, A2: experimental O2uptake values

B = (B1+B2)/2

D1 = 100(A1-B)/ThOD*[S]

D2 = 100(A2-B)/ThOD*[S]

D = (D1+D2)/2

ThOD: 1.67 mg O2/mg

[S]: Initial reference substance concentration (mg/L)

*: malfunction of the measuring head, not used for this study

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Aldehyde C9 Nonylic Food Grade is readily biodegradable.

Description of key information

The test substance was assessed for biodegradability according to OECD guideline 301F.  The test substance was readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The test substance was assessed for biodegradability according to OECD guideline 301F and underwent 83% biodegradation after 28 days (87% after 61 days). The 10 day window was also fulfilled (23% biodegradation on day 1 and 71% on day 11). The test substance is regarded as readily biodegradable according to this test. Similar high levels of degradation were observed in an inherent 302C study (84% after 28 days).