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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: well performed OECD study with GLP

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
according to
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:

Test material


Study design

Oxygen conditions:
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Municipal sewage treatment plant, 0-31137 Hildesheim
Activated sludge from the sewage plant at Hildesheim is well suited as it comprises mostly municipal sewage and hardly industrial chemical waste.
The activated sludge is maintained in an aerobic condition by aeration for four hours and then homogenized with a mixer. The sludge is filtered and the filtrate (30 [mL]) is subsequently used to initiate inoculation.
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
15 mg/L
Based on:
test mat.
Initial conc.:
12.1 mg/L
Based on:
other: ThTOC
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
Test vessels: 5000 [mL], brown glass
Volume of the test medium: 3000 [mL]
Test medium: Mineral nutrient solution acc. to OECD 301 Bf CO2 Evolution Test

Colony forming units of the inoculum: 10exp7 - 10exp8 [CFU/L]
Colony forming units in the tests vessels: 10exp5 - 10exp6 [CFU/L]

FUNCTIONAL CONTROL Sodium acetate, puriss single
TEST SUBSTANCE: Hostasol-Rot GG duplicate
CONTROL Nutrient solution and inoculum duplicate
TOXICITY CONTROL (Test substance in test concentration, reference substance in test concentration and inoculum) single
Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

% Degradationopen allclose all
% degradation (CO2 evolution)
Sampling time:
1 d
Remarks on result:
other: replicate 2
% degradation (CO2 evolution)
Sampling time:
14 d
Remarks on result:
other: replicate 2
% degradation (CO2 evolution)
Sampling time:
21 d
Remarks on result:
other: replicate 2
% degradation (CO2 evolution)
Sampling time:
28 d
Remarks on result:
other: replicate 2

BOD5 / COD results

Results with reference substance:
Day CO2-production [mg CO2] mean value
1 1.9
6 23.1
11 46.7
18 77.1
25 94.8
28 102.2

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
other: not readily biodegradable
Based on the test result the substance must be regarded to be not readily biodegradable
Executive summary:

The ready biodegradability of the test substance was determined in the Modified Sturm Test (OECD guideline 301B) with a non adapted activated domestic sludge over a priod of 28 days. The test substance was tested in a concentration of 15 [mg/L] in duplicates, corresponding to a carbon content (ThTOG) of 12.1 [mgC/L]. The biodegradation of the test substance was followed by titrimetric analyses of the quantity of CO2 which was produced by the respiration of bacteria. The degradation was finished on day 28 by acidification, the last titration was made on day 29, after the soluble CO, was turned out over a period of 24 [h]. The CO2- production was calculated as the percentage of total CO2 that the test substance could have theoretically produced based on carbon composition. Biodegradation is therefore expressed as percentage ThCO2 (calculated by the sum formula) and was calculated for each titration of CO2. In order to check the activity of the study system sodium acetate was used as functional control. The percentage degradation of the functional control reached the pass level of> 60 % after 14 days with a degradation rate of 61% at this point of time. The quality criterion of the guideline is fulfilled. In the toxicity control containing both test substance and reference compound a biodegradation of 21 % occured within 14 days. The biodegradation came to a maximum of 33 % after 28 days. After a long lasting adaptation phase of 22 days the 10% level (begin of biodegradation) was reached only in one replicate. In this replicate the biodegradation came to a maximum of about 20 % after 28 days. In the second replicate the biodegradation lasted under the 10 % level. The test substance must be regarded to be not readily biodegradable in the 10 [d]-window and after 28 days.