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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:
2003-09-22 to 2004-02-10
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:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source: predominantly domestic wastewater treatment plant, ARA Ergolz II, Füllinsdorf, Switzerland
- Preparation of inoculum for exposure:
* Washing procedure: The sludge was washed twice with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized
aliquot of the final sludge suspension was weighed, dried, and the ratio wet to dry weight was calculated.
* Based on the wet to dry weight ratio, calculated amounts of sludge were suspended in test water at 4 g dw/L. During holding prior to use (1 day), sludge was aerated at room temperature until use.
* Prior to use, sludge was thoroughly mixed and diluted to 1 g dw/L for use as inoculum.
- Initial biomass concentration in test: 30 mg dw/L test medium
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: test water prepared according to test guidelines.
- Additional substrate: no
- Test temperature: 22°C
- pH: 7.4-8.0, measured prior to testing in each test flask before addition of inoculum, and again in each test flask at the end of the incubation period
- pH adjusted: yes, from 7.8 to 7.4 with a diluted HCL solution
- Suspended solids concentration: intially 30 mg dw/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 500-mL Erlenmeyer flasks , fill-volume 250 mL, SAPROMAT D12 (Voith GmbH, Heidenheim, Germany)
- Number of culture flasks/concentration: 2
- Oxygen consumption was recorded manually by taking a daily reading at least each working day.
- Measuring equipment: by electro-chemical analysis process.
- Test performed in open system: not stated

CONTROL AND BLANK SYSTEM
- Inoculum control: yes, two replicates without test substance with inoculum
- Abiotic sterile control: one replicate poisoned with mercury dichloride at a concentration of 10 mg/L
- Toxicity control: yes, one replicate with test substance, reference substance, and inoculum
- Procedure control: yes, 2 replicates with reference substance and inoculum

Reference substance:
benzoic acid, sodium salt
Parameter:
% degradation (O2 consumption)
Remarks:
BOD/ThOD
Value:
5
Sampling time:
28 d
Results with reference substance:
Average % degradation was 86% by exposure day 14 and 89% by exposure day 28, confirming suitability of the activated sludge.
Points of degradation plot (reference substance):
1 % degradation after 1 d
69.5 % degradation after 4 d
73.5 % degradation after 5 d
77 % degradation after 6 d
78 % degradation after 7 d
80.5 % degradation after 8 d
82 % degradation after 9 d
83.5 % degradation after 10 d
84 % degradation after 11 d
84.5 % degradation after 12 d
86 % degradation after 13 d
86 % degradation after 14 d
87 % degradation after 15 d
87 % degradation after 16 d
88 % degradation after 17 d
87 % degradation after 18 d
87.5 % degradation after 19 d
88.5 % degradation after 20 d
88 % degradation after 21 d
88.5 % degradation after 22 d
89 % degradation after 23 d
89 % degradation after 24 d
89.5 % degradation after 25 d
89 % degradation after 26 d
89.5 % degradation after 27 d
89 % degradation after 28 d
Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
This study determined the ready biodegradability of T002251 in a 28-day manometric respirometry test according to OECD guideline 301F in the presence of activated sludge (30mg SS/L) from a waste water treatment plant treating mainly domestic sewage. The test substance was found to not be biodegradable under the test conditions. The results of the test can be considered reliable without restriction.

Description of key information

One study (Grutzner, 2004) is included in this dossier and regarded as a key study (Klimisch score of 1).  The biodegradability of T002251 was determined according to OECD Guideline 301F and EU Method C.4-D. Under the conditions of the test, T002251 was determined to be not biodegradable within 28 days.

Key value for chemical safety assessment

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

Additional information