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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:
From 18 January 2016 to 11 March 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
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
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 1000100003
- Expiration date of the lot/batch: 13.10.2017
- Purity: 92%
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Sewage Treatment Plant ”Czajka” , Warsaw receiving predominantly domestic sewage.
- Storage conditions: No storage
- Preparation of inoculum for exposure: Preconditioned, the inoculum was aerated, at the test temperature of 22 °C, until application next day.
- Pretreatment: The coarse particles were removed by settling and the supernatant was discarded. The sludge was washed in the mineral medium. The concentrated sludge was suspended in mineral medium to yield a concentration of 3-5 g suspended solids/l.
- Water filtered: no



Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: inoculum 30 mg/l suspended solids, 50-100mg ThOD/l, concentration of elements in mineral medium:
P =116 mg/l, N = 1.3 mg/l, Na=86 mg/l, K = 122 mg/l, Mg = 2.2 mg/l, Ca 9.9 mg/l, Fe = 0.05-0.1 mg/l.
- Solubilising agent (type and concentration if used): Mineral medium was performed mixing 10 ml of solution containing:
Monopotassium dihydrogen orthophosphate, KH2PO4 8.50 g/l
Dipotassium monohydrogen orthophosphate, K2HPO4 21.75 g/l
Disodium monohydrogen orthophosphate dihydrate Na2HPO4 · 2 H2O 33.40 g/l
Ammonium chloride, NH4Cl 0.50 g/l
with 800 ml of dilution water. Then it was added 1 ml of calcium chloride, anhydrous, CaCl2 27.50 g/l, 1ml of magnesium sulphate heptahydrate, MgSO4 · 7 H2O 22.50 g/l and 1 ml of Iron(III) chloride hexahydrate, FeC13 · 6H2O 0.25 g/l and it was made up to 11 with dilution water.
- Test temperature: 22 ± 2°C
- pH: 7.4 ± 0.2
- pH adjusted: yes
- Suspended solids concentration: 30 mg/l SS
- Organic carbon of dilution water: 3 mg/l of organic carbon

TEST SYSTEM
- Culturing apparatus: thermo-cabinet WTW TS 606 CZ-G/3-VAR
- Number of culture flasks/concentration:
Flasks# 1, 2, 3: Test suspension containing test item (100 mg/l) and inoculum 30 mg/l SS.
Flasks# 7, 8 and 9: Inoculum blank containing only inoculum 30 mg/l SS.
Flask# 10, 11 and 12: Procedure control containing reference item (sodium acetate 100 mg/l) and inoculum 30 mg/SS.
Flask# 4, 5 and 6: Toxicity control: containing test item, reference item at the same concentrations as in the individual solutions and inoculum 30 mg/l SS.
- Method used to create aerobic conditions: stirrers were used and it was checked for air-tightness.
- Measuring equipment: closed WTW OxiTop OC 110 respirometer for BOD determination and spectrophotometer Hach DR 3900 and 45600 reactor COD concentration measurements.
- Test performed in closed vessels due to significant volatility of test substance: yes
- Details of trap for CO2 and volatile organics if used: The carbon dioxide, evolved during test item degradation, was absorbed in a solution of potassium hydroxide.

SAMPLING
- Sampling frequency: The data were read out every 112 min
- Sampling method: a controller was used

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, three inoculum blanks
- Abiotic sterile control: yes, only mineral medium was used.
- Toxicity control: yes, containing test item, reference item at the same concentrations as in the individual solutions and inoculum 30 mg/l SS

STATISTICAL METHODS: The calculations and the graphs were performed using SigmaP lot 9.0 software of SYSTAT Software, Inc., USA.
Reference substance:
acetic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
BOD/ThOD
Value:
82.5
St. dev.:
0.3
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Remarks:
BOD/ThOD
Value:
60
Sampling time:
7 d
Details on results:
At the 28th day of the test the aerobic biodegradation of the testing:
- In the toxicity test the biodegradation was equal to 67.4% in 14 days.As more than 25% of biodegradation (based on ThOD NH4) occurred in 14 days, the test item can not be assumed to be inhibitory.
- The oxygen uptake of the inoculum blank was equal to 54.8 mg/l in 28 days.
- The pH values of all flasks were inside the range 7.19-8.60.
Results with reference substance:
The reference item reached 78.4% of biodegradation and the level for ready biodegradability by 5 days.

Sample oxygen uptake: biodegradability

 

time, days

3

5

7

9

12

14

16

18

21

23

25

28

Test item O2uptake, mg/l

a1

52.4

83.6

102.0

115.0

128.9

138.9

164.0

165.0

168.0

169.9

172.0

173.6

a2

53.9

86.2

105.5

117.5

129.4

141.2

160.9

165.8

169.2

169.7

172.2

174.5

a3

48.4

78.3

98.2

112.2

125.3

137.9

160.7

162.6

167.0

169.3

172.3

174.0

am. avg

51.5

82.7

101.9

114.9

127.9

139.4

161.9

164.5

168.1

169.6

172.2

174.0

Blank test O2uptake. mg/l

b1

6.7

13.8

17.7

22.9

25.6

33.3

51.6

53.5

56.2

56.3

56.3

59.7

b2

3.3

8.8

13.3

17.4

19.7

27.8

45.0

46.2

48.1

48.2

50.6

50.6

b3

9.0

13.6

17.5

19.7

25.6

30.3

46.8

47.8

50.8

50.6

51.0

54.1

bm. avg

6.3

12.1

16.2

20.0

23.6

30.5

47.8

49.2

51.7

51.7

52.6

54.8

Reference item O2uptake. mg/l

w1

52.0

64.0

73.6

79.3

87.9

95.3

113.2

113.5

115.0

115.7

118.2

118.8

w2

44.6

57.2

67.9

73.5

79.9

90.7

107.2

107.0

110.8

113.0

113.0

115.4

w3

48.6

61.7

71.1

76.7

82.1

90.3

107.2

107.5

109.8

110.0

110.0

113.6

wm. avg

48.4

61.0

70.9

76.5

83.3

92.1

109.2

109.3

111.9

112.9

113.7

115.9

Toxicity control O2uptake. mg/l

tox1

63.2

91.5

118.7

141.5

163.7

177.2

200.0

205.0

211.3

217.8

221.4

227.6

tox2

70.1

101.7

128.2

149.3

171.9

184.6

208.1

213.0

217.1

219.0

222.0

225.8

tox3

74.8

102.9

128.1

146.5

167.4

179.5

203.3

208.3

214.4

217.7

220.6

225.3

toxm. avg

69.4

98.7

125.0

145.8

167.6

180.4

203.8

208.8

214.3

218.2

221.3

226.2

Corrected

test item O2uptake, mg/l

(a1-bm)

46.1

71.5

85.8

95.0

105.3

108.5

116.2

115.9

116.3

118.2

119.4

118.8

(a2-bm)

47.6

74.1

89.4

97.5

105.8

110.7

113.1

116.6

117.5

118.0

119.6

119.7

(a3-bm)

42.0

66.2

82.0

92.2

101.7

107.5

112.9

113.4

115.3

117.6

119.7

119.2

Reference item

% degradation

ThOD = 0.78

mgO2/mg

C = 100 mg/l

R1(w1)

58.5

66.5

73.7

76.1

82.3

83.1

83.9

82.5

81.2

82.0

84.1

82.0

R1(w2)

49.1

57.8

66.3

68.6

72.2

77.3

76.2

74.1

75.8

78.6

77.4

77.7

R3(w3)

54.2

63.7

70.4

72.7

75.0

76.8

76.2

74.8

74.5

74.7

73.5

75.4

Rwavg

54.0

62.7

70.2

72.4

76.5

79.1

78.8

77.2

77.2

78.5

78.3

78.4

Test item

% degradation

ThOD = 1.57

mgO2/mg

C = 92 mg/l

R1(a1)

31.9

49.5

59.4

65.8

72.9

75.1

80.4

80.2

80.5

81.8

82.6

82.2

R1(a2)

32.9

51.3

61.9

67.5

73.2

76.7

78.3

80.7

81.3

81.7

82.8

82.8

R3(a3)

29.1

45.8

56.8

63.8

70.4

74.4

78.2

78.5

79.8

81.4

82.8

82.5

Raavg

31.3

48.9

59.4

65.7

72.2

75.4

79.0

79.8

80.6

81.6

82.8

82.5

Toxicity control

% degradation

 

 

R1(tox1)

25.6

35.7

46.1

54.6

63.0

66.0

68.4

70.0

71.8

74.7

75.9

77.7

R2(tox2)

28.7

40.3

50.4

58.1

66.6

69.3

72.1

73.6

74.3

75.2

76.1

76.9

R3(tox3)

30.8

40.8

50.3

56.9

64.6

67.0

69.9

71.5

73.1

74.6

75.5

76.6

Rtoxavg

28.3

38.9

48.9

56.5

64.7

67.4

70.1

71.7

73.1

74.8

75.8

77.1

The pH values of test flasks

flask #

1

2

3

7

8

9

10

11

12

4

5

6

Test item

Control

Reference item

Toxicity test

initial

7.12

7.22

7.42

7.48

7.50

7.54

7.57

7.47

7.46

7.45

7.45

7.46

final

7.22

7.23

7.26

7.27

7.19

7.20

8.37

8.43

8.60

8.13

8.53

8.35

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test substance can be considered readily biodegradable within 28 days based on the oxygen demand (BOD and ThOD).
Executive summary:

A 28-day ready aerobic biodegradability test through the manometric respirometry method was performed with the test substance according to OECD 301F / EC C.4 – D under GLP conditions. A 100 mg/L of test item was inoculated with non-adapted activated sludge (30 mg/L SS) and incubated under aerobic conditions in a closed respirometer flask at constant temperature 22ºC(± 2) for 28 days. A blank test, a procedure test with reference substance (sodium acetate) and a toxicity test were run in parallel. The validity criteria was considered fulfilled. The substance was mostly degraded (82.5%) within the 28-day period based on BOD (based on measurements of oxygen uptake) and ThOD. Thus the test substance can be deemed to be readily biodegradable.

Description of key information

Key study: Test method according to OECD 301F. GLP study. The substance was mostly degraded (82.5%) within a 28-day period. The test substance is regarded as ready biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information