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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:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Quantitative Structure - Biodegradability relationships for alcohols, ketones and alicyclic compounds.
Author:
Vaishnav D.D., Boethling R.S. and Babeu L.
Year:
1987
Bibliographic source:
Chemosphere, Vol.16, No.4, pp 695-703, 1987

Materials and methods

Principles of method if other than guideline:
The 5-day BOD value ahs been determined using acclimated inocula of wastewater origin and using the techique according to APHA 1980 (American Public Health Association (1980) Standard methods for the examination of water and wastewater, 15th ed. American Public Health Association, Washington, D.C., p. 70).
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic, adapted
Details on inoculum:
- Inoculum: acclimated microbial cultures capable of degrading alcohols and ketones as sole carbon and energy sources were obtained by a conventional enrichment technique.
- Source of inoculum: domestic sewage.
- Incubation: mineral salts medium (prepared according to the OECD,1981) containing chemical and sewage was incubated on a rotary shaker (120 rpm) at 21 ± 3 °C.
- Storage: cultures were stored individually at 4 °C in 0.2 M phosphate buffer (pH 6.8), containing 100 µl/l of the enrichment substrate.
- Initial cell/biomass: 1 ml of acclimated seed.
Duration of test (contact time):
5 d
Initial test substance concentration
Initial conc.:
250 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Test temperature: 21 ± 3 °C

TEST SYSTEM
- Culturing apparatus: 300-ml BOD bottles, filled with 20 ml of dilution water. The bottles were then filled to capacity with dilution water, sealed, and incubated.
- Number of culture flasks: 8 replicates.
- Measuring equipment: YSI 54 oxygen meter with a self stirring probe.

SAMPLING
- Sampling frequency: Sampling was performed on the first day (t = 0 days) and on the 5th day (t = 5 days) for the measurement of dissolved oxygen
- DO concentration

EVALUATION
Biodegradation of the alcohols and ketones was determined using the BOD technique (American Public Health Association (1980) Standard methods for the examination of water and wastewater, 15th ed. American Public Health Association, Washington, D.C., p. 70).
The DO concentrations in randomly selected bottles were determined by the azide modification of the iodometric titration method. BOD values showing unadjusted DO depletions of at least 2 mg/l and residual DO of at least 1 mg/l were corrected for the seed BOD, and used to calculate a mean BOD for the chemical.

TEST ITEM CONCENTRATIONS
Initial concentrations of test chemical in the BOD bottles ranged from 0 to 3.2 µl/l, and never exceeded the water solubility of the chemical.

Results and discussion

% Degradation
Remarks on result:
not measured/tested

BOD5 / COD results

BOD5 / COD
Remarks on result:
other: details below

Any other information on results incl. tables

The mean 5-day BOD resulted 5.61 (SD: 0.17) mmol BOD/ mmol test chemical. The percentage of ThOD was estimated to be 59.1 and the log P 1.58.

The most probable degradation pathway for ketons involves insertion of an oxygen atom next to the keto group by a ketone monooxygenase, producing an ester that is subsequently hydrolyzed, presumably to products that are easily degraded. The log (% removal) appears to be linearly correlated with log P.

Applicant's summary and conclusion

Conclusions:
The mean 5-day BOD resulted 5.61 (SD: 0.17) mmol BOD/ mmol test chemical.
Executive summary:

The 5-day BOD value ahs been determined using acclimated inocula of wastewater origin and using the techique according to APHA 1980 (American Public Health Association (1980) Standard methods for the examination of water and wastewater, 15th ed. American Public Health Association, Washington, D.C., p. 70).

The mean 5-day BOD resulted 5.61 (SD: 0.17) mmol BOD/ mmol test chemical. The percentage of ThOD was estimated to be 59.1 and the log P 1.58.

The most probable degradation pathway for ketons involves insertion of an oxygen atom next to the keto group by a ketone monooxygenase, producing an ester that is subsequently hydrolyzed, presumably to products that are easily degraded. The log (% removal) appears to be linearly correlated with log P.

Conclusion

The mean 5-day BOD resulted 5.61 (SD: 0.17) mmol BOD/ mmol test chemical.