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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
24 AUG - 21 SEP 1993
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): sewage treatment plant Marl-Ost, predominantely domestic
- Water filtered: yes
- Type and size of filter used, if any: white-band paper filter
Duration of test (contact time):
28 d
Initial conc.:
2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral salt medium
- Test temperature: 19.0 - 21.5 °C
- Continuous darkness: yes/no


TEST SYSTEM
- Culturing apparatus: 300 mL BSB-glas flasks


SAMPLING
- Sampling frequency: 0, 7, 14, 21 and 28 days



CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
Reference substance:
benzoic acid, sodium salt
Parameter:
% degradation (O2 consumption)
Value:
-3
Sampling time:
28 d
Parameter:
BOD5
Value:
1.49 mg O2/g test mat.
Results with reference substance:
70% after 28 days

 

% O2-consumption

Day

7

14

21

28

Test substance

-3

-9

-7

-3

Interpretation of results:
under test conditions no biodegradation observed

Description of key information

The substance is not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
not biodegradable
Type of water:
freshwater

Additional information

The ready biodegradability of chloroethane (CAS 75-00-3) was investigated in a Closed Bottle Test according to the EU Method C4. –E (Schöberl, 1993). In the test domestic activated sludge was used as inoculum. The oxygen consumption of the inoculum was followed over an incubation period of 28 days. The oxygen demand of -3% was determined after 28 days.Thus, biodegradation of the test substance could not be demonstrated.

Literature data predict a half-life of the substance of 1-4 weeks in surface water under aerobic conditions (Printup, 1991). Whereas a degradation rate of 13% after 107 days was reported for the degradation under anaerobic conditions (Vogel and McCarty, 1987). Comparable results were predicted by Printup (1991) for the aqueous biodegradation (not acclimated) under anaerobic conditions (half-life 28 days - 16 weeks).