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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Data is from experimental study report
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (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.
- Preparation of inoculum for exposure: The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernant and resuspending in mineral medium) and kept aerobic until being used on the same day.
- Cocnentration of inoculum: To obtain a concentration of 30 mg/l (dry weight) in a 250 ml flask, 2.28 ml of sludge is needed (inoculum).

Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Remarks:
BOD
Details on study design:
TEST CONDITIONS
- Composition of medium: 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 litres with deionised water. The pH is measured and if necessary adjusted to 7.4 +/- 0.2 with phosphoric acid or potassium hydroxide.
- Test temperature: 22°C.
- pH: 7.4 +/- 0.2
- pH adjusted: yes, if necessary pH was adjusted to 7.4 +/- 0.2 with phosphoric acid or potassium hydroxide.
- Suspended solids concentration: 3.289 g/l (dry weight).
- Other: The water used during this study is deionised water containing less than 10 mg/l dissolved organic carbon.

TEST SYSTEM
- Measuring equipment: The respirometer used during this study is an SAPROMAT D 12, made by J. M. VOITH GmbH, Heidenheim, Germany.
Reference substance:
benzoic acid, sodium salt
Remarks:
(100 mg/l) (Purity: mn. 99%)
Key result
Parameter:
% degradation (O2 consumption)
Value:
93
Sampling time:
28 d
Remarks on result:
other: Readily biodegradable
Details on results:
Oxygen uptakes, as read on the SAPROMAT meters, are corrected by deducing the basic oxygen uptake of sludge (flask 1/7 and 1/8) and proportionally to account for the small differences between actual and nominal concentrations of test and reference substances. Test chemical undergoes 93% biodegradation after 28 days in the test conditions. Biodegradation starts on day 3 and reached 80% at the end of the 10-day window (day 3 to 13).
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 and the test is considered as valid.

Biodegradability: Respirometric method

Test substance

Study no.:99-E106

1.      Theoretical Demand

Formula: C15H14N0O3

Mol. Wt.: 242.27 g/mol

Theoretical Oxygen Demand (ThOD): 2.25 mg O2/mg

2.      Biodegradability

Biological Oxygen Demand (BOD, mg O2/l, adjusted to nominal concentrations):

 

 

 

Days

3

7

13

14

21

28

BOD sludge

1stflask     B1

2ndflask    B2

Mean        B

6.0

16.0

16.0

17.0

19.0

21.0

6.0

16.0

16.0

18.0

21.0

21.0

6.0

16.0

16.0

17.0

20.0

21.0

BOD Test subs.

1stflask     C1

2ndflask    C2

1stfl. Corr. C1-B

2ndfl. Corr. C2-B

75.0

144.2

189.9

198.6

224.9

229.8

72.2

149.4

203.9

209.8

225.4

229.8

69.0

128.2

173.9

181.1

204.9

208.8

66.2

133.4

187.9

192.3

205.4

208.3

% degr.

1stflask     D1

2ndflask    D2

Mean        D

31

57

77

81

91

93

29

59

84

85

91

93

30

58

80

83

91

93

B = (B1 + B2)/2

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

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

D = (D1 + D2)/2

[S] = initial test substance concentration (mg/l)

Biodegradability: Respirometric method

Reference substance:Sodium benzoate 

Study no.:12-E023

1.      Theoretical Demand

Formula: C7        H5          O2         Na1

Mol. Wt.: 144.1 g/mol

Theoretical Oxygen Demand (ThOD):1.67 mg O2/mg

2.      Biodegradability

Biological Oxygen Demand (BOD, mg O2/l, adjusted to nominal concentrations):

 

 

 

Days

3

7

13

14

21

28

BOD sludge

1stflask     B1

2ndflask    B2

Mean        B

14.0

16.0

16.0

17.0

19.0

21.0

13.0

16.0

16.0

18.0

21.0

21.0

13.5

16.0

16.0

17.5

20.0

21.0

BOD Refer. subs.

1stflask     A1

2ndflask    A2

1stfl. Corr. A1-B

2ndfl. Corr. A2-B

134.0

150.0

162.0

168.0

174.0

176.0

131.0

146.0

160.0

170.0

176.0

179.0

120.5

134.0

146.0

150.5

154.0

155.0

117.5

130.0

144.0

152.5

156.0

158.0

% degr.

1stflask     D1

2ndflask    D2

Mean        D

72

80

88

90

92

93

71

78

86

92

94

95

71

79

87

91

93

94

B = (B1 + B2)/2

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

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

D = (D1 + D2)/2

[S] = initial test substance concentration (mg/l)

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Test chemical undergoes 93% biodegradation after 28 days in the test conditions. Biodegradation starts on day 3 and reached 80% at the end of the 10-day window (day 3 to 13). Thus, test chemical is considered as readily biodegradable. The curves obtained with the reference substance alone and with test chemical plus reference substance shows no toxic effect of test chemical to the micro-organisms at the test concentration.
Executive summary:

The ready biodegradability of test chemical was determined in accordance with the OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test). Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage was used. The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernant and resuspending in mineral medium) and kept aerobic until being used on the same day. Initial test substance concentration used in the study was 100 mg/l. 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 litres with deionised water. The pH is measured and if necessary adjusted to 7.4 +/- 0.2 with phosphoric acid or potassium hydroxide. The water used during this study is deionised water containing less than 10 mg/l dissolved organic carbon. Suspended solids concentration used in the study was 3.289 g/l. To obtain a concentration of inoculum of 30 mg/l (dry weight) in a 250 ml flask, 2.28 ml of sludge is needed (inoculum). Sodium benzoate (100 mg/l) (purity min. 99.0%) was used as a reference substance. Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days, the activity of the inoculum was thus verified and the test is considered as valid. Test chemical undergoes 93% biodegradation after 28 days in the test conditions. Biodegradation starts on day 3 and reached 80% at the end of the 10-day window (day 3 to 13). The curves obtained with the reference substance alone and with test chemical plus reference substance shows no toxic effect of test chemical to the micro-organisms at the test concentration (100 mg/l). Thus, test chemical is considered as readily biodegradable.

Description of key information

The ready biodegradability of test chemical was determined in accordance with the OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test) (Experimental study report, 2000). Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage was used. The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernant and resuspending in mineral medium) and kept aerobic until being used on the same day. Initial test substance concentration used in the study was 100 mg/l. 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 litres with deionised water. The pH is measured and if necessary adjusted to 7.4 +/- 0.2 with phosphoric acid or potassium hydroxide. The water used during this study is deionised water containing less than 10 mg/l dissolved organic carbon. Suspended solids concentration used in the study was 3.289 g/l. To obtain a concentration of inoculum of 30 mg/l (dry weight) in a 250 ml flask, 2.28 ml of sludge is needed (inoculum). Sodium benzoate (100 mg/l) (purity min. 99.0%) was used as a reference substance. Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days, the activity of the inoculum was thus verified and the test is considered as valid. Test chemical undergoes 93% biodegradation after 28 days in the test conditions. Biodegradation starts on day 3 and reached 80% at the end of the 10-day window (day 3 to 13). The curves obtained with the reference substance alone and with test chemical plus reference substance show no toxic effect of test chemical to the micro-organisms at the test concentration (100 mg/l). Thus, test chemical is considered as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

The ready biodegradability of test chemical was determined in accordance with the OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test) (Experimental study report, 2000). Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage was used. The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernant and resuspending in mineral medium) and kept aerobic until being used on the same day. Initial test substance concentration used in the study was 100 mg/l. 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 litres with deionised water. The pH is measured and if necessary adjusted to 7.4 +/- 0.2 with phosphoric acid or potassium hydroxide. The water used during this study is deionised water containing less than 10 mg/l dissolved organic carbon. Suspended solids concentration used in the study was 3.289 g/l. To obtain a concentration of inoculum of 30 mg/l (dry weight) in a 250 ml flask, 2.28 ml of sludge is needed (inoculum). Sodium benzoate (100 mg/l) (purity min. 99.0%) was used as a reference substance. Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days, the activity of the inoculum was thus verified and the test is considered as valid. Test chemical undergoes 93% biodegradation after 28 days in the test conditions. Biodegradation starts on day 3 and reached 80% at the end of the 10-day window (day 3 to 13). The curves obtained with the reference substance alone and with test chemical plus reference substance show no toxic effect of test chemical to the micro-organisms at the test concentration (100 mg/l). Thus, test chemical is considered as readily biodegradable.