Registration Dossier

Diss Factsheets

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Link to relevant study record(s)

biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Au 08, 2018 - Jan 15, 2019
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to guideline
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Principles of method if other than guideline:
GLP compliance:
Oxygen conditions:
Inoculum or test system:
activated sludge, domestic, adapted
Details on inoculum:
Sludge collection: a fresh sample of activated sludge was collected on Oct. 11th, 2018 from the aeration tank of the Long Hua Wastewater Treatment Plant in Shanghai which treats predominantly domestic sewage with Anacrobic-Oxic process(A/O). The activated sludge was kept by aeration until used(non-aeration during transport from the wastewater treatment plant to the laboratory was kept to a minimum).

Sludge treatment: When back to the laboratory, the sludge was washed with mineral medium. After centrifugation, the supernatant was decanted. This procedure was repeated three times(4000 rpm, 4 °C, centrifuge 20 minutes). Then, 0.416 g of the concentrated sludge was weighed, dried at 105°C for 1h and then measured by moisture meter for 1h to determine the dry weight. The dry weight of concentrated sludge was 6.73%. .

Sludge suspension: According to the dry weight, 44.58 g of concentrated sludge was calculated and suspended in 1 L mineral medium to yeild a concentration of 3 g suspended solids/L. The final concentration of the activated sludge in the test medium was 30 mg/L.
Duration of test (contact time):
28 d
Initial conc.:
50.8 mg/L
Based on:
final concentration was clearly above water solubility
Parameter followed for biodegradation estimation:
O2 consumption
Reference substance:
benzoic acid, sodium salt
Key result
% degradation (O2 consumption)
Sampling time:
28 d
Details on results:
During the 28-day test period, the biochemical oxygen demand (BOD) of test substance didn't increase from test start until test termination after 28d in comparison with that of the blank control group and didn't reach the 10-days window.
Therefore, the test substance cannot be considered to be readily biodegradable under the experimental conditions according to this test method.
Results with reference substance:
The reference Item sodium sodium benzoate was sufficiently degraded to 72 % after 14 days, respectively. The percentage degradation of the reference item confirms the suitability of the used activated sludge inoculum.
Validity criteria fulfilled:
Interpretation of results:
under test conditions no biodegradation observed
Under the test conditions no biodegradation of test item could be observed. The percentage degradation did not exceed 60 % within the 10-day window and after 28 days of incubation. The test item is considered not readily biodegradable.

Description of key information

OECD 301F: not readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:

Additional information