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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:
Jan 04 - May 18, 1994
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
according to
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
GLP compliance:

Test material


Study design

Inoculum or test system:
other: effluent from sewage plant
Details on inoculum:
Secondary effluent from a sewage plant was collected on the day of initiation of the test period. The sample was filtered through a paper filter, the first 200 ml were discarded. The remainder of the fIltrate was diluted 1:100 with physiological salt solution and kept under aerobic conditions at room temperature. The total count of viable cells in the fIltrate was in the order of magnitude of 1()6eFU/ml (colony forming units).
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
1.2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
The test was performed in an air-conditioned test room to maintain a constant temperature of 20 +/- 1°C. However, this range of temperature was exceeded on day 0, the minimum and maximum average (two test bottles) temperatures for all series being 21.2/21.3°C. Since the deviation from the recommended temperature range was slight and all series were affected in a similar manner, the observed discrepancy would seem unlikely to influence the validity of the results.
Test series:
C: control: dilution water, mineral nutrient solutions without inoculum
B: inoculation blank
dilution water, mineral nutrient solutions and 50 uIll of inoculum.
R: reference: dilution water, mineral nutrient solutions, 50 ul/1 of inoculum and 2 ml of the reference solution (sodium benzoate, 1 g/l) => test concentration 2 mg/l
T: sample: 20 ml of the test article stock solution, mineral nutrient solutions as well as 50 ul of inoculum. => test concentration 1.2 mg/l
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Key result
% degradation (O2 consumption)
Sampling time:
28 d
Details on results:
The chemical oxygen demand of the reference substance sodium benzoate and the test article was determined experimentally according to IBR SOP/91/X/04 based on photometric analysis of COD using COD test vials (0-1500 mg COD/mg, HACH).

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
not readily biodegradable
The percentage biodegradation of the test substance was 21.5% at the end of the test under the conditions of the study, so the test substance cannot be considered to be readily biodegradable.