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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Municipal activated sludge from the wastewater treatment plant of Mannheim, Germany
- Storage conditions: The inoculum was collected on 16 January 2017 from the aeration tank of the plant. A suitable aliquot of the activated sludge suspension was sieved by a finely woven mesh with a mesh size about 1 mm. To reduce the content of inorganic carbon in the blank controls the activated sludge was aerated with carbon dioxide free air for about 48 hours at 22 ± 2° C.
- Preparation of inoculum for exposure: At the day of exposure the suspension was washed one time with drinking water. Therefore the aeration was stopped and the sludge was allowed to settle. After settling the supernatant was discarded and the remaining sludge suspension was filled up with drinking water and the concentration oft the sludge was adjusted to 6.0 g/L dry weight.
- Pretreatment: none
- Concentration of sludge: Aliquots of 7.5 mL were added to the test vessels to obtain an activated sludge concentration of 30 mg/L dry weight.
Duration of test (contact time):
28 d
Initial conc.:
20 mg/L
Based on:
TOC
Remarks:
approx. 26 mg/L test substance
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: according to guideline
- Test temperature: 22 ± 2° C
- pH: 7.4 ± 0.2
- pH adjusted: yes
- Suspended solids concentration: 30 mg/L dry weight

TEST SYSTEM
- Culturing apparatus: 2 L incubation bottles
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: with carbon dioxide free air for about 48 hours
- Measuring equipment: The TIC- and DOC-analyses were performed as repeat determination, using a TOCanalyzer equipped with an auto sampler (Shimadzu TOC-5000A and/or TOC-L, or TOCCSN).
- Details of trap for CO2 and volatile organics if used: The bottles were connected to two serial scrubbing bottles (total volume 250 mL) filled with 100 mL 0.05 mol sodium hydroxide solution for the adsorption of carbon dioxide from biodegradation processes. Usually twice a week the Total Inorganic Carbon (TIC) values of the adsorption solutions of the first trap were determined and used for the calculation of the produced carbon dioxide. After each sampling the second trap was moved forward and the new trap with fresh sodium hydroxide solution was placed into the second position. Each trap was analyzed separately.

SAMPLING
- Sampling frequency: twice a week

Reference substance:
aniline
Parameter:
% degradation (CO2 evolution)
Value:
80 - 90
Sampling time:
28 d
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
80-90 %CO2/ThCO2 after an exposure period of 28 days. C9-11 Methacrylate was readily biodegradable under the conditions of this test.

Description of key information

C9 -11 Methacrylate was tested for ready biodegradability in the Carbon Dioxide Evolution Test (OECD 301B). The test concentration was 20 mg/L TOC nominal, equiv. to approx. 26 mg/L test substance. Activated sludge from a municipal sewage plant were used (municipal waste water treatment plant Mannheim, Germany). Based on the rate of biodegradation of 80-90 % CO2/ThCO2 at the end of exposure the test substance can be evaluated as readily biodegradable in this test.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information