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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
23 May - 21 Jun 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP - Guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Qualifier:
according to
Guideline:
ISO DIS 9439 (Ultimate Aerobic Biodegradability - Method by Analysis of Released Carbon Dioxide)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Name of test material (as cited in study report): PM-5927
- Physical state: off-white powder
- Lot/batch No.: 07-02
- Expiration date of the lot/batch: 05 Feb 2008
- Storage condition of test material: at room temperature in the dark

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Municipal sewage treatment plant: ‘Waterschap de Maaskant’, ‘s-Hertogenbosch, The Netherlands
- The sludge was kept under continuous aeration until further treatment.
- Preparation of inoculum for exposure: Before use, the sludge was allowed to settle for 73 min and the liquid decanted for use as inoculum at the amount of 20 mL/L of mineral medium.
- The concentration of suspended solids was 2.5 g/L in the concentrated sludge.
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
21 mg/L
Based on:
test mat.
Initial conc.:
12 mg/L
Based on:
other: TOC
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral medium
- Test temperature: 20.6 - 21.7 °C
- pH: 7.5 - 7.7
- Aeration of dilution water: The mixture of mineral components, Milli-RO water (ca. 80% total volume) and inoculum (1% final volume) was aerated with synthetic air overnight to purge the system of CO2.
- Suspended solids concentration: 2.5 g/L
- other: The test media were continuously aerated and stirred during the test. Preparation of the test solutions was as much as possible performed under yellow light.

TEST SYSTEM
- Culturing apparatus: 2 litre all-glass brown coloured bottles
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: CO2-free air was sparged through the scrubbing solutions at a constant rate.
- Details of trap for CO2: A mixture of oxygen (21%) and nitrogen (79%) was passed through a bottle, containing 0.5 – 1 L 0.0125 M Ba(OH)2 solution. The CO2 produced in each test bottle reacted with the barium hydroxide in the gas scrubbing bottle and precipitated out as barium carbonate.

SAMPLING
- Sampling frequency: on day 2, 5, 7, 9, 14, 19, 23, 27, 29
- Sampling method: The amount of CO2 produced was determined by titrating the remaining Ba(OH)2 with 0.05 M standardized HCL. On the 28th day, the pH of the test suspensions was measured and 1 mL of concentrated HCL was added to each bottle. The bottles were aerated overnight to drive off CO2 present in the test suspension. The final titration was made on day 29.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates
- Positive control: 1 replicate
- Toxicity control: 1 replicate
Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

% Degradation
Parameter:
% degradation (CO2 evolution)
Value:
5.5
Sampling time:
29 d

BOD5 / COD results

Results with reference substance:
Degradation: 64% after 14 days, 60% pass level was reached.

Any other information on results incl. tables

Table 1: Percentage biodegradation of test substance, reference substance and toxicity control

Day

Test substance (% degradation)

Reference substance

(% degradation)

Toxicity control

(% degradation)

Replicate 1

Replicate 2

Ø

2

0

1

1

2

0

5

1

2

1

35

13

7

1

2

2

49

20

9

2

3

2

57

24

14

2

3

3

64

28

19

4

3

3

68

31

23

5

3

4

71

33

27

6

3

5

74

34

29

6

3

5

76

34

29

7

3

5

76

35

29

8

3

5*

77

35

 * value as stated in report, actual mean = 5.5

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
CLP: Aquatic chronic 2, H411 (basis for classification: not rapidly biodegradable and a NOEC (growth rate) of 0.22 mg/L for algae)