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Environmental fate & pathways

Biodegradation in water: screening tests

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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:
guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 311 (Anaerobic Biodegradability of Organic Compounds in Digested Sludge: Measurement of Gas Production)
GLP compliance:
this test was not carried out initially to meet the REACH registration requirement, hence the fact that it is not carried out under GLP.

Test material

Constituent 1
Reference substance name:
Test material form:

Study design

Oxygen conditions:
Inoculum or test system:
anaerobic sludge
Details on inoculum:
Digested anaerobic digester sludge was collected on April 11, 2018 at the Reventin-vaugris treatment plant. The sludge was transported to the laboratory in tightly closed containers.
The sludge was washed twice with mineral medium as follows:
The sludge is centrifuged at 3000 g for 5 minutes then the supernatant is removed. The sludge is then resuspended in deoxygenated mineral medium.
Duration of test (contact time):
60 d
Initial test substance concentration
Initial conc.:
ca. 101.7 mg/L
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CH4 evolution
Details on study design:
974 / 5000
Résultats de traduction
The test solutions are carried out in triplicates for each condition. The bottles were then closed with the measuring heads.
The vials were incubated in an enclosure at 35 ° C ± 2 ° C for one hour and then the excess gas was removed. After this equilibration time, the test begins with the recording of data by the measuring heads.
The test was performed in an enclosure at 35 ° C ± 2 ° C, with continuous orbital shaking and in the dark.
After 24 hours of incubation, agitation was stopped to check the anaerobic conditions of the test.
The test medium containing an oxygen indicator (resazurin), the absence of pink coloration in the test vials demonstrated strict compliance with anaerobic conditions.
At the end of the test period (60 days), the vials were allowed to stand and then a fraction of the supernatant liquid was analyzed with the carbon analyzer to determine the amount of dissolved inorganic carbon.
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Key result
% degradation (CH4 evolution)
ca. 87.2
Sampling time:
60 d

BOD5 / COD results

Results with reference substance:
The reference control shows a biodegradability greater than 60% in 60 days (87.2%)
The pH at the end of the test is well within the range 7 ± 1

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
readily biodegradable
Executive summary:

The objective of this study was to evaluate the potential anaerobic biodegradability of the test element in an anaerobic digester over a period of 60 days according to OECD Test Guideline 311 (23 March 2006).
The test element at approximately 50 mg / L carbon per liter was incubated in mineral dilution medium and inoculated with anaerobic digester slurry approximately 10 times diluted and pre-washed. The test was performed in hermetically sealed vials.
The increase in pressure in the headspace (located above the liquid in the vessels) caused by the production of carbon dioxide and methane was measured.
Under the conditions of the test, an appreciable proportion of the CO2 produced is dissolved in the liquid phase or transformed into carbonate or hydrogen carbonate. This inorganic carbon was measured at the end of the test.
The amount of carbon (inorganic and methane) released by the biodegradation of the test substance is calculated from the net gas production and the net formation of inorganic carbon in the liquid phase in excess of that found in the control vessels. The extent of biodegradation is calculated from the production of total inorganic carbon and methane carbon and expressed as a percentage of the measured or calculated amount of carbon added by the test element.
Test solutions were prepared by diluting a stock solution.
The study is valid:
- The percentage of biodegradation of the reference element is greater than 60% in 60 days (87.2%)
- The pH at the end of the test is well within the range 7 ± 1


the results are the following:

% biodegradation at d 6095%
ConclusionBiodegradable in anaerobiosis