Hydrocarbons, C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%)

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Not available

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

yes

Remarks:

test was run for 31 days

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Somerset-Raritan Valley Sewage Authority, Bridgewater, New Jersey
- Storage length: sludge was obtained one day before the test
- Preparation of inoculum for exposure: sludge was homogenized by mixing in a blender at medium speed for 2 min. It was then allowed to settle for 30 min. The supernatent was decanted, and the filtered supernatent used to determine microbial activity
- Pretreatment: 24 L of distilled water was placed in a 50 L carboy. The following solutions were added: 24 mL of magnesium sulfate, 24 mL of calcium chloride, 240 mL phosphate buffer, 24 mL ferric chloride, and 240 mL of sludge supernatent. The carboy was then aerated for 24 h with CO free air.
- Initial cell/biomass concentration: 10^6 colony forming units/mL
- Water filtered: yes
- Type and size of filter used, if any: glass

Duration of test (contact time):

31 d

Initial conc.:

32.5 mg/L

Based on:

test mat.

Initial conc.:

38.5 mg/L

Based on:

test mat.

Initial conc.:

36.1 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: 24 mL of magnesium sulfate, 24 mL of calcium chloride, 240 mL phosphate buffer, 24 mL ferric chloride, and 240 mL of sludge supernatent in distilled water
- Test temperature: 22±1 °C
- Aeration of dilution water: aerated for 24 h prior to test

TEST SYSTEM
- Number of culture flasks/concentration: 3
- Measuring equipment: electrolytic respirometer from Co-ordinated Environmental Service, Kent, England
- Test performed in closed vessels due to significant volatility of test substance: yes
- Details of trap for CO2 and volatile organics if used: manometric cell/CO2 trap

SAMPLING
- Sampling frequency: hourly
- Sampling method: aerobic respirometer

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes

STATISTICAL METHODS: Results were analysed using Lotus v2.2

Reference substance:

benzoic acid, sodium salt

Remarks:

5.0 mL of a 6,115 mg C/L solution

Parameter:

% degradation (O2 consumption)

Value:

13.8

Sampling time:

4 d

Parameter:

% degradation (O2 consumption)

Value:

60

Sampling time:

11 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

74.7

Sampling time:

28 d

Parameter:

% degradation (O2 consumption)

Value:

75.9

Sampling time:

31 d

Results with reference substance:

The reference substance was degraded > 60%, therefore the test is valid.

Table: Daily Percent Biodegradation

Day	Average % Degradation of Sodium Benzoate	Average % Degradation of Test Material
1	21.5	0
2	55.4	1.52
3	64.3	7.81
4	72.7	13.8
5	77.5	21.9
6	80.4	28.8
7	83.3	34.2
8	87.4	39.8
9	94.1	45.8
10	99.0	52.9
11	101.2	60.0
12	102.0	64.3
13	101.4	67.1
14	99.0	68.0
15	96.0	67.7
16	92.9	67.2
17	91.5	67.6
18	90.7	68.1
19	90.2	68.8
20	89.8	69.4
21	89.7	70.2
22	89.5	70.9
23	89.4	71.6
24	89.2	72.3
25	89.1	73.0
26	88.9	73.6
27	88.8	74.1
28	88.7	74.7
29	88.6	75.2
30	88.5	75.6
31	88.5	75.9

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test substance biodegraded to an extent of 74.7% after 28 days with an unacclimated sewage sludge inoculum. The test substance was determined to be readily biodegradable.

Executive summary:

The purpose of this study was to determine the ready biodegradability of Hydrocarbons, C10-C13, n-alkanes, isoalkanes, cyclics, 2-25% aromatics. 35 mg/L of test substance was added to test vessels inoculated with activated sludge. The oxygen consumption of the sludge was then monitored for 31 days. Sodium benzoate was used as a reference substance. The reference substance was 88.7% degraded in 28 days, therefore the test is valid. The test substance was 74.7% degraded by day 28 and met the 10 -day window requirement for >60% degradation. The test substance is readily biodegradable.

Description of key information

There is no data available for Hydrocarbons, C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%). However, data is available for structural analogue Hydrocarbons, C10-C13, n-alkanes, isoalkanes, cyclics, aromatics (2-25%). This data is read across to based on analogue read across and a discussion and report on the read across strategy is provided as an attachment in IUCLID Section 13.

Hydrocarbons, C10-C13, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), biodegraded 75% after 28 days under the conditions of the study and is readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable