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Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2021

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2-fluoro-4-methyl-1,3,2-dioxaphospholane

Cas Number:

16415-09-1

Molecular formula:

C3H6FO2P

IUPAC Name:

2-fluoro-4-methyl-1,3,2-dioxaphospholane

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

Inoculum used in this study was collected from 11 sites in Korea including 5 rivers(Gangjeongnaru, Mulgeum, Gwangju, Daejeon, Paldang), 2 industrial wastewater treatment plants(Dalseo, Yeosu) and 4 domestic sewage treatment plants(Dalseo, Gumi, Busan, Jungrang). Fresh samples collected from these sites at Setemper 2020 were incubated for over one month.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

10 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

BOD(Biochemical Oxygen Demand)

Details on study design:

The test was performed in the incubator to maintain a 25±1 ºC and reading of the BOD meter was recorded once a day. And the inoculum was treated at a concentration of about 10e+7~10e+8 cells/L.
After putting a sample in a BOD test bottle and treating activated sludge with a concentration of about 10e+7~10e+8 cells/L, the test was performed in an incubator to maintain a temperature of 25±1 ºC, and the reading of the BOD meter was recorded once a day.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

18.6

Sampling time:

28 d

Remarks on result:

other: not readily biodegradable

Details on results:

There was no environmental condition which might have affected the reliability of the test results and the test temperature was maintained at 24.4~25.8 ºC during the test by monitoring of datalogger.
BOD concentrations of the inoculum blank(bottle 6) for 28 days were 0.0~15.8 mg O2/L(Appendix 1).
These values were within the acceptable range(less than 60 mg O2/L for inoculums blank) specified by the OECD guideline.
The change of BOD concentrations for the test bottles was measured by BOD meter for 28 days. The difference of replicate value for the treatments(bottle 2, 3 and 4) at the end of the test was 3.9 % which was less than 20 % specified by the OECD guideline(Appendix 1).
The pH values at the end of BOD measurement were 7.41, 7.45 and 7.42 for test bottle 2, 3 and 4, respectively. These values were within the acceptable range(6.0~8.5 for pH) specified by the OECD guideline.
The percentage biodegradations of test substance, FCCA-04, based on BOD measurement were a range of 12.5~23.3 % and the average percentage biodegradation was calculated to be 18.6 % after 28 days.
This value was less than pass level of biodegradability specified by the guideline(Table 3).
After 28 days of the test, the residual amount of the test substance through analysis could not be calculated from the average concentration of the test substance group(test bottles 2, 3, 4) based on the concentration of the abiotic control(test bottle 1) because the test substance was not detected in all test bottles including the abiotic control.

BOD5 / COD results

Results with reference substance:

The percentage biodegradations of the reference compound(Sodium benzoate) were 68.8 % after 7 days and 65.3 % after 14 days and were within the acceptable range(greater than 40 % after 7 days and 65 % after 14 days) specified by the OECD guideline(Table 2).

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test substance could not be concluded as readily degradable by microorganisms in the aquatic environment. The average percentage biodegradation of the test substance by BOD measurement after 28 days was calculated to be 18.6 % which was less than pass level of biodegradability(60%) specified by the OECD guideline.