reaction products of 1 mole of Benzenesulfonic acid, 4-C10-13-sec-alkyl derivs and 1 mole of cyclohexylamine

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

On December 5th, 2017 activated sludge was sampled at Valence’s Waste treatment Plant (France). The sludge was settled and the liquid supernatant discarded. The concentrated sludge was then suspended in the mineral solution. These two steps were repeated twice.

Duration of test (contact time):

28 d

Initial conc.:

484.9 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Test containers
The test was performed in white glass bottles of 610 mL.

Apparatus
Thermostatic chamber.
pHmeter
Common laboratory equipment

Measuring system (heads and oxitop controller)
The respirometric measurement is based on pressure measurement. If oxygen is consumed in a closed vessel at a constant temperature and the produced CO2 is trapped, a decrease of pressure happens and can be measured. If a gas is released, an overpressure develops. The measuring head stores these pressure variations for the whole duration of a test once started. These heads allow the measurement at a programmed time interval of the pressure in the bottle. The different parameters (volume of the bottle and volume of filling) are also parameterized allowing a direct measurement of the Biological Oxygen Demand in the bottles. The data are then recovered by infra-red transmission using the Oxitop® controller and transferred to computer.

Method
After rinsing the sludge, the concentration of suspended solids was then determined. An activated sludge volume was filtered on a 1.2 µm filter with a vacuum pump. Then, the filter was dried in drying oven at 105 °C and weighted. Final suspended solid concentration was 30 mg/L.
The ThOD of the test item was calculated from an elemental composition analysis. ThOD was 0.3204 mg O2 / mg test item.
Eight bottles were prepared according to table 1. The flasks were closed with the measuring heads and stirred with a magnetic stirrer.
The test was performed in an enclosure at 21 ° C ± 1 in the dark. The CO2 released was trapped by soda pellets and the oxygen consumption was derived from the measurement of pressure decrease. The BOD (Biological Oxygen Demand) values were extracted from the measurement heads using an "Oxitop® controller".
Nitrites and nitrates were measured at the beginning and the end of the test in order to apply corrections to biodegradation values with regards to the theoretical formation of these compounds when nitrogenous compounds are tested.

Reference substance:

benzoic acid, sodium salt

Preliminary study:

None.

Key result

Parameter:

% degradation (O2 consumption)

Value:

68.7

Sampling time:

28 d

Details on results:

Based on a biodegradation rate higher than 60% in 14 days (experimental value: 80.0 and 77.9 % in 9 days) in the reference control, the test was carried out under good conditions. At the end of the test, measurements of Biological Oxygen Demand (BOD) in two replicates of the test item solution did not show a difference of more than 20% (experimental value:3.7%). The oxygen uptake of the control was not greater than 60 mg/l in 28 days (experimental value: 27.1 mg O2/L)
Based on a biodegradation rate higher than 25% in 14 days (experimental value: 70.1% in 13 days) in the toxicity control, the test item was not toxic to micro-organisms. No significant Biological Oxygen Demand was observed in the abiotic control over the test period.
With a biodegradation of 68.7% after 28 days, the test item is considered readily biodegradable.

Key result

Parameter:

ThOD

Value:

0.305 g O2/g test mat.

Results with reference substance:

Based on a biodegradation rate higher than 60% in 14 days (experimental value: 80.0 and 77.9 % in 9 days) in the reference control, the test was carried out under good conditions.

Biological Oxygen Demand(mg O₂.L^-1)

	BOD mg O2/L
Time (Days)	Control A	Control B	Reference control A	Reference control B	Test item solution A	Test item solution B	Toxicity control	Abiotic control
0.0	0	0	0	0	0	0	0	0
0.5	0	0	1.9	0	0	0	1.9	9.7
1.0	0	1.9	52.2	48.4	1.9	1.9	65.8	7.7
2.0	5.8	7.7	77.4	77.4	5.8	23.2	137	9.7
3.0	9.7	9.7	101	98.6	25.1	25.1	149	11.6
4.0	11.6	11.6	133	130	34.8	32.9	172	9.7
6.0	15.5	13.5	149	147	77.4	77.4	188	9.7
9.0	17.4	17.4	162	161	92.8	87	236	11.6
13.0	21.3	21.3	172	168	103	98.6	250	9.7
20.0	27.1	25.1	178	180	124	114	267	9.7
28.0	27.1	27.1	184	186	137	130	286	11.6
Nitrification correction	24.4	24.3	181.7	183.5	133.4	127.5	284.5	0.0

 

Biodegradation percentage

	Biodegradation (%)
Time (Days)	Reference control A	Reference control B	Test item solution A	Test item solution B	Toxicity control	Abiotic control
0.0	0	0	0	0	0	0
0.5	1.1	0.0	0.0	0.0	0.6	6.2
1.0	30.5	27.9	0.6	0.6	19.5	4.3
2.0	42.0	41.5	-0.6	10.7	39.2	1.9
3.0	54.3	52.3	10.0	10.0	41.9	1.2
4.0	72.2	69.6	15.0	13.8	48.2	-1.2
6.0	80.0	77.9	40.7	40.7	52.2	-3.1
9.0	86.0	84.4	48.8	45.1	65.8	-3.7
13.0	89.0	85.6	52.3	50.7	68.5	-5.6
20.0	90.3	91.6	64.7	56.9	73.1	-10.6
28.0	93.3	93.4	71.2	66.7	77.9	-10.0
28.0 with nitrification correction	93.6	93.6	70.6	66.8	78.2	-15.7

 

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Dodecylbenzene sulfonate stoechiometrically compounded with cyclohexylamine is readily biodegradable.

Executive summary:

The objective of this study was to assess the aerobic ready biodegradability of dodecylbenzene sulfonate stoechiometrically compounded with cyclohexylamine by measurement of manometric respirometry over a 28-day period according to the OECD 301F guideline (July 1992). The test item, at 500 mg/L, as the sole source of carbon and energy, was incubated in a buffer-mineral salts medium which was inoculated with a mixed population of micro-organisms. The consumption of oxygen was determined from the change in pressure in the apparatus. Evolved carbon dioxide was absorbed in a solution of sodium hydroxide. The amount of oxygen taken up by the microbial population during biodegradation of the test substance (corrected for uptake by blank inoculum, run in parallel) was expressed as a percentage of ThOD.

The test solutions were prepared by direct dilution of the test item.

The study is valid since:

Based on a biodegradation rate higher than 60% in 14 days (experimental value: 80.0 and 77.9 % in 9 days) in the reference control, the test was carried out under good conditions.

At the end of the test, measurements of Biological Oxygen Demand (BOD) in two replicates of the test item solution did not show a difference of more than 20% (experimental value:3.7%).

The oxygen uptake of the control was not greater than 60 mg/l in 28 days (experimental value: 27.1 mg O2/L)

Based on a biodegradation rate higher than 25% in 14 days (experimental value: 70.1% in 13 days) in the toxicity control, the test item was not toxic to micro-organisms.

Any significant Biological Oxygen Demand of the abiotic control over the test period was highlighted. The degradation of test item was not abiotic.

Since the test element is a multiconstituent (DDBS and CHA), the 10 -day window does not apply to the "readily biodegradable" character. 68.7% biodegradation were observed at the end of the test. The test item is considered readily biodegradable.

Description of key information

The objective of this study was to assess the aerobic ready biodegradability of dodecylbenzene sulfonate stoechiometrically compounded with cyclohexylamine by measurement of manometric respirometry over a 28-day period according to the OECD 301F guideline (July 1992). The test item, as the sole source of carbon and energy, was incubated in a buffer-mineral salts medium which was inoculated with a mixed population of micro-organisms. The consumption of oxygen was determined from the change in pressure in the apparatus. Evolved carbon dioxide was absorbed in a solution of sodium hydroxide. The amount of oxygen taken up by the microbial population during biodegradation of the test substance (corrected for uptake by blank inoculum, run in parallel) was expressed as a percentage of ThOD.

The test solutions were prepared by direct dilution of the test item.

The study is valid since:

Based on a biodegradation rate higher than 60% in 14 days (experimental value: 80.0 and 77.9 % in 9 days) in the reference control, the test was carried out under good conditions.

At the end of the test, measurements of Biological Oxygen Demand (BOD) in two replicates of the test item solution did not show a difference of more than 20% (experimental value:3.7%).

The oxygen uptake of the control was not greater than 60 mg/l in 28 days (experimental value: 27.1 mg O2/L)

Based on a biodegradation rate higher than 25% in 14 days (experimental value: 70.1% in 13 days) in the toxicity control, the test item was not toxic to micro-organisms.

Any significant Biological Oxygen Demand of the abiotic control over the test period was highlighted. The degradation of test item was not abiotic.

Since the test element is a multiconstituent, the 10 -day window does not apply to the "readily biodegradable" character. 72% biodegradation were observed at the end of the test. The test item is considered readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable