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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:
21 May 1999 - 21 July 1999
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
Qualifier:
according to
Guideline:
ISO DIS 9408 (Ultimate Aerobic Biodegradability - Method by Determining the Oxygen Demand in a Closed Respirometer)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Municipal activated sludge from laboratory wastewater treatment plants fed with municipal sewage- Concentration of sludge: 30 mg/L
Duration of test (contact time):
45 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Reference substance:
aniline
Remarks:
100 mg/L
Preliminary study:
Inhibition of bacteria: Activated Sludge Respiration Inhibition Test- EC20 > 1,000 mg/L (nominal)- Incubation time: 30 min
Key result
Parameter:
% degradation (O2 consumption)
Value:
>= 30 - <= 40
Sampling time:
28 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
>= 80 - <= 90
Sampling time:
61 d
Details on results:
Degradation (%) of test substance after 28 d: 30-40Degradation (%) of test substance after 61 d (end of test): 80-90Degradation (%) of test substance in abiotic control after 45 d (end of test): 0-10Degradation (%) of reference substance after 14 d: 70-80Degradation (%) of inhibition control after 14 d: 40-50ThOC of test material: 615 mg/gThOD of test material: 2,148 mg/g
Results with reference substance:
% Degradation after 14 d (%BOD/ThOD): 70-80
Validity criteria fulfilled:
yes
Remarks:
% degradation after 14 d of reference substance and inhibition control was > 60 % and > 25 %, respectively; Oxygen demand in blank control < 60 mg/L at end of test; pH values ranged from pH 6-8.5
Interpretation of results:
inherently biodegradable, not fulfilling specific criteria
Conclusions:
Under the test conditions, the test substance was considered biodegradable but not readily biodegradable according to OECD criteria.
Executive summary:

A study was performed to assess the biodegradability of the test substance in an aerobic aqueous medium according to OECD Guideline 301 F, ISO DIS 9408 and EU Method C.4-D.

At a concentration of 100 mg/L (ThOC: 615 mg/g; ThOD: 2,148 mg/g), the test substance was exposed to activated sludge in a closed flask for 61 days (adaptation phase: 10 days and degradation phase: 45 days). The degradation of the test substance was assessed by the determination of the amount of oxygen consumed. Control solutions containing the reference material, aniline, together with abiotic control and inhibition control were used for validation purposes.

The test substance attained 30-40% degradation after 28 days and 80-90 % degradation by the end of test. Degradation % in abiotic control, inhibition control and reference control were 0-10 (at end of test), 40-50 and 70-80 (after 14 days).

Under the test conditions, the test substance was considered biodegradable but not readily biodegradable as it did not meet the OECD criteria.

Description of key information

A study was performed to assess the biodegradability of amine synergist in an aerobic aqueous medium according to OECD Guideline 301F, ISO DIS 9408 and EU Method C.4-D. Within 28 d, the substance only degraded up to 30-40% and is therefore not readily biodegradable. However, with a prolonged test period of two months (61 days), the substance was shown to degrade to > 80% (Beimborn, 1999) and can be considered inherently biodegradable (not fulfilling specific criteria).

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable, not fulfilling specific criteria

Additional information