Fluoren-9-one

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

14 Dec 2018 - 28 Dec 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)

Deviations:

yes

Remarks:

The duration of the test was 14 days instead of 28 days, as stated in the OECD guideline. The validity criteria were met, thus the test is considered valid.

Test guideline 2

Qualifier:

according to guideline

Guideline:

ISO 9888 Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium - Static test (Zahn-Wellens method)

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Fluoren-9-one

EC Number:

207-630-7

EC Name:

Fluoren-9-one

Cas Number:

486-25-9

Molecular formula:

C13H8O

IUPAC Name:

9H-fluoren-9-one

Test material form:

not specified

Details on test material:

Tested samples were water samples containing several contaminants. No further details on the test substance were reported for this sample.

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of inoculum: taken from the Sponsor's wastewater treatment plant (no further details provided)
- Concentration of sludge: 2.0 g suspended substance/L
- Initial cell/biomass concentration (of suspended substance): 29 g suspended solids/L

Duration of test (contact time):

14 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

0.06 mg/L

Based on:

test mat.

Remarks:

spike concentraion of 9-fluorenone

Initial test substance concentration 2

Initial conc.:

ca. 514 - ca. 525 mg/L

Based on:

DOC

Remarks:

non-spiked samples [flasks F(TI) and F(TII)]

Initial test substance concentration 3

Initial conc.:

ca. 514 - ca. 532 mg/L

Based on:

DOC

Remarks:

spiked samples [flasks F(TIII) and F(TIV)]

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation 1

Parameter followed for biodegradation estimation:

DOC removal

Parameter followed for biodegradation estimation 2

Parameter followed for biodegradation estimation:

other: Chemical Oxygen Demand (COD)

Details on study design:

TEST CONDITIONS
- Test temperature: 20-25°C
- pH: adjusted to 7.0 +/- 0.5
- Suspended solids concentration: 29 g/L
- Continuous darkness: diffused light

TEST SYSTEM
- Culturing apparatus: flasks (2 L and 250 mL)
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aerobic conditions were maintained by bubbling air from an air pump through a long glass tube attached to the bottom of the flask
- Measuring equipment: not specified
- Other: before taking samples from the flasks, water loss due to evaporation was made up with deionized water. After sampling, a new mark was made at the new medium level.

SAMPLING
- Sampling frequency: on t=0h, 3h, 3d, 7d and 14d. Except for flasks containing sterile medium, which were only samples on t=0 and 14d.
- Sampling method: not specified

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, consisting of 138 mL inoculum, added up to 2000 mL with deionized water
- Abiotic sterile control: yes, consisting of the sample spiked with the test substance and deionized water. The sterile medium was filtered through a membrane filter and kept under sterile conditions to prevent bacterial growth.
- Toxicity control: yes, containing the sample spiked with the test substance, the reference compound (ethylene glycol) and inoculum.

STATISTICAL METHODS: no statistical analysis was performed.

CALCULATION OF RESULTS:
The percentage degradation of DOC (or COD) was calculated with the following equation:
DT=(1-(ct-cBt)/(c0-cB0))*100
where
c0 is the concentration of DOC (or COD) at time 0 in each test flask.
cB0 is the concentration of DOC (or COD) at time 0 in the blank flask.
ct is the concentration of DOC (or COD) at time t in each test flask.
cBt is the concentration of DOC (or COD) at time t in the blank flask.

Reference substance

Reference substance:

ethylene glycol

Results and discussion

% Degradation

% Degradation 1

Key result

Parameter:

% degradation (DOC removal)

Value:

85

Sampling time:

14 d

Remarks on result:

other: non-spiked sample Flask TI

% Degradation 2

Key result

Parameter:

% degradation (DOC removal)

Value:

86

Sampling time:

14 d

Remarks on result:

other: non-spiked sample Flask TII

% Degradation 3

Key result

Parameter:

% degradation (DOC removal)

Value:

86

Sampling time:

14 d

Remarks on result:

other: spiked sample Flask TIII

% Degradation 4

Key result

Parameter:

% degradation (DOC removal)

Value:

85

Sampling time:

14 d

Remarks on result:

other: spiked sample Flask TIV

Details on results:

- Based on <20% reduction of DOC after 3 h, it was shown that no physicochemical adsorption of the test substance to the inoculum had taken place.
- Toxicity to microorganisms could not be assessed as the experiment was interrupted before degradation has reached a plateau. However, the reduction of DOC in test vessels containing the test substance, showed that the sample did not inhibit microorganisms.
- The test substance was shown to be not inhibitory to the inoculum as degradation in the inhibition control corresponded to the degradation of the reference compound.
- DOC reduction in the abiotic sterile controls was <20%, showing that no significant abiotic elimination had taken place.

BOD5 / COD results

BOD5 / COD

BOD5 / COD 1

Parameter:

COD

Value:

ca. 86 - ca. 87 other: % reduction

Remarks on result:

other: spiked samples Flask TIII and Flask TIV

BOD5 / COD 2

Parameter:

COD

Value:

ca. 85 - ca. 86 other: % reduction

Remarks on result:

other: non-spiked samples Flask TI and Flask TII

Results with reference substance:

After 14 days, DOC content in the test sample containing the reference substance was 83 mg/L, indicating a DOC removal of 82%.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

Degradation of the reference compound was >70% on day 14.

Interpretation of results:

inherently biodegradable

Conclusions:

In the OECD 302B test, water samples spiked with Fluoren-9-one were biodegraded for 86% and 87% in duplicate samples tested, after 14 days of inoculation. Non-spiked samples were biodegraded for 85% and 86%. Based on these results, the samples can be considered inherently biodegradable.