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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2019 - 01 - 09 - 2019 - 03 - 20
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report date:
2019

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
Principles of method if other than guideline:
Commission Regulation 440/2008/EC, Method C.4-D of May 30, 2008: Manometric Respirometry Test (EEC Publication No. L 142/496, May 2008)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Test material form:
liquid

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic, non-adapted
Details on inoculum:
Species/Origin:
Aerobic activated sludge, microorganisms from a domestic waste water treatment plant was supplied by the sewage treatment plant Rossdorf, Germany.

Conditioning:
The aerobic activated sludge used for this study was deposited for 30 min, washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in test water and centrifuged again. This procedure was done three times. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 3.5 g dry material per litre were mixed with test water (see 6.5) and aerated overnight. This suspension was used for the experiment.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Manometric Test System with test flasks containing a volume of approximately 500 mL.
BSB/BOD-Sensor-System

The test flasks were incubated at 22°C * 1°C. The pressure decrease in the reaction vessels was measured over complete experimental phase of 28 days using the BSB/BOD-Sensor-System. The test flasks were closed gas-tight by a measuring head. Potassium hydroxide solution (45%) was used for trapping the produced carbon dioxide. The amount of O2 consumed by the activated sludge was calculated from the decrease of pressure in the reaction vessel.

Surrounding Type: Climatised chamber
Temperature: 22°C ± 1°C
Light conditions: Darkness
pH-Value of Test Solutions: 7.6 (measured at the start of the test)
7.4 to 8.2 (measured at the end of the test)


Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Key result
Parameter:
% degradation (CO2 evolution)
Value:
39
St. dev.:
4
Sampling time:
28 d
Details on results:
Biodegradation of the test item methyl-bis(2-arylpropyl)dihydro-heteropolycycle:
Nitrogen is part of the molecular structure of the test item; therefore the evaluation of biodegradation has to be based on ThODNH4 and ThODNO3. The criterion for ready biodegradability under the conditions of a manometric respirometry test is the degradation of the test item of at least 60%, reached within a 10-day window; the 10-day window starts when the degradation of the test item reaches at least 10% degradation.

The mean biodegradation of 10% of methyl-bis(2-arylpropyl)dihydro-heteropolycycle was reached at day 22 (ThODNH4, ThODNO3). The mean biodegradation at test end after 28 days was 39% (ThODNH4) and 37% (ThODNO3).
Therefore, the test substance methyl-bis(2-arylpropyl)dihydro-heteropolycycle is considered to be not readily biodegradable based on ThODNH4 and ThODNO3.

BOD5 / COD results

Results with reference substance:
Biodegradation of Sodium Benzoate:

The reference item sodium benzoate was sufficiently degraded to 84% after 14 days and to 90% after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used.

Any other information on results incl. tables

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
Biodegradation of Test Item:

The degradation rate of methyl-bis(2-arylpropyl)dihydro-heteropolycycle did not reach 60% after 28 days.
Therefore, the test item methyl-bis(2-arylpropyl)dihydro-heteropolycycle is considered to be not readily biodegradable.

Biodegradation of Reference Item Sodium Benzoate
The percentage biodegradation of the reference item confirms the suitability of the used aerobic activated sludge inoculum.
Executive summary:

Biodegradation of Test Item:

The degradation rate of methyl-bis(2-arylpropyl)dihydro-heteropolycycle did not reach 60% after 28 days.

Therefore, the test item methyl-bis(2-arylpropyl)dihydro-heteropolycycle is considered to be not readily biodegradable.

Biodegradation of Reference Item Sodium Benzoate

The percentage biodegradation of the reference item confirms the suitability of the used aerobic activated sludge inoculum.

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