Dodecyltrimethylammonium bromide

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:

2018-01-30 to 2018-03-08

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:

- Source of activated sludge: Sewage treatment plant Rossdorf, Germany
- Preparation of inoculum for exposure: The aerobic activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted after 15 minutes of deposition. The solid material was re-suspended in test water and centrifuged again. This procedure was done three times. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined.
- Concentration of sludge: 3.5 g dry material per litre

Duration of test (contact time):

28 d

Initial conc.:

101.8 mg/L

Based on:

test mat.

Remarks:

corresponding to an oxygen demand of about 240.5 mg/L (ThODNH4) and 261.6 mg/L (ThODN03)

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Reconstituted water according to guideline using pure water and analytical grade salts
- Additional substrate: No
- Test temperature: 22°C ± 1°C
- pH:
6.6 - 6.7 (measured at the start of the test and ad¬justed to 7.4 - 7.5)
7.0 to 7.7 (measured at the end of the test)
- pH adjusted: No
- Aeration of dilution water: No
- Continuous darkness: Yes

TEST SYSTEM
- Culturing apparatus: Manometric Test System with test flasks containing a volume of approximately 500 mL; closed test flasks were incubated in a climatised chamber under continuous stirring
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: Inoculum aerated
- Measuring equipment: BSB/BOD-Sensor-System, Aqualytic Dortmund, Germany
- Test performed in closed vessels due to significant volatility of test substance: Closed gas-tight by a measuring head
- CO2 trap: Potassium hydroxide solution (45%)


SAMPLING
- Sampling method and frequency: The change of pressure in the test flasks was measured by means of a manometric method (BSB/BOD-Sensor-System, Aqualytic Dortmund, Germany) each day. Nitrogen determination was done using a AA3 Continuous Flow Analyzer and equipment.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 1 flask
- Abiotic sterile control: No
- Toxicity control: Yes, containing both, the test item and the reference item sodium benzoate

Reference substance:

benzoic acid, sodium salt

Preliminary study:

None

Test performance:

VALIDITY OF THE STUDY
Inoculum control: The oxygen demand of the inoculum control (medium and inoculum) was 33 mg O2/L and thus not greater than 60 mg O2/L within 28 days as required by the test guideline.
pH value: The pH-value of the test item flasks at the end of the test was 7.3 to 7.0 and therefore within the range of pH 6.0 to 8.5 as required by the test guideline.
Reference control: The reference item sodium benzoate was degraded to more than 60% after 4 days of incubation.
Difference of duplicate values: < 20% (for the degradation of the test item at the end of the test and at the end of the 10-day window)
Toxicity Control: If in a toxicity test, containing both the test item and a reference item less than 25% biodegradation (based on total ThOD) occurred within 14 days, the test item can be assumed to be inhibitory. The biodegradation was 60% (based on ThODNO3) at day 14; the test item was not inhibitory.

Key result

Parameter:

% degradation (O2 consumption)

Value:

73

Sampling time:

28 d

Remarks on result:

other: % ThODNH4

Details on results:

The mean biodegradation of 10% of the test item was reached at day 3 (ThODNO3). At the end of the 10-day window at day 13, the mean degradation of the test item was 67% (ThODNO3) and therefore the 10 day window criterion was passed. The mean biodegradation at test end after 28 days was 67% (ThODNO3) and 73% (ThODNH4). The nitrate concentration in the controls after 28 days of incubation was 1.982 mg/L (mean). The nitrate concentration in the test item treated vessels was 0.026 mg/L (LOQ mean). Hence, a nitrification occurred. In the case of a nitrification, or transformation of ammonium to nitrate the degradation of the test item was 73% after 28 days.

Results with reference substance:

The reference item sodium benzoate was sufficiently degraded to 85% after 14 days and to 83% (ThODNH4) after 28 days of incubation. The percentage biodegradation of the reference item confirms the suitability of the used aerobic activated sludge inoculum.

Table 1: Cumulative Biochemical Oxygen Demand (mg O₂/L) in Test Flasks during the Test Period of 28 Days

	Flask No.
Time (days)	1	2	3	4	5	6	7
1	0	0	0	0	60	0	15
2	5	5	0	0	85	0	105
3	15	75	5	5	105	0	135
4	130	135	5	5	120	0	165
5	165	140	5	5	130	0	230
6	170	145	5	10	135	0	245
7	190	160	10	10	140	0	265
8	190	175	10	10	145	0	270
9	190	180	10	10	150	0	270
10	190	180	10	10	150	0	270
11	195	185	10	15	150	0	275
12	195	185	15	15	155	0	275
13	195	185	15	15	155	0	275
14	200	185	15	15	160	0	275
15	200	190	15	15	160	0	275
16	200	190	15	15	160	0	275
17	205	195	20	20	165	0	275
18	205	195	20	20	165	0	275
19	205	200	20	25	165	0	275
20	205	200	25	25	170	0	275
21	210	200	25	25	170	0	275
22	210	200	25	30	170	0	275
23	210	200	25	30	170	0	280
24	210	200	30	35	170	0	280
25	210	200	30	35	170	0	280
26	210	205	30	35	175	0	280
27	210	205	30	35	175	0	280
28	210	205	30	35	175	0	280

Flasks 1 and 2: test item

Flasks 3 and 4: inoculum control

Flask 5: reference (procedure control)

Flask 6: abiotic control

Flask 7: toxicity control

Table 2:

Time (Days)	Percentage Biodegradation^1
	Test item		Sodium Benzoate^2	Toxicity control^1, 2
	Flask 1 [%]	Flask 2 [%]	Flask 5 [%]	Flask 7 [%]
1	0	0	35	3
2	2	2	50	24
3	4	27	59	30
4	47	50	67	37
5	60	52	73	52
6	61	53	75	54
7	68	58	76	58
8	68	64	79	60
9	68	66	82	60
10	68	66	82	60
11	69	67	81	60
12	68	66	82	60
13	68	66	82	60
14	70	66	85	60
15	70	68	85	60
16	70	68	85	60
17	70	68	85	58
18	70	68	85	58
19	69	69	83	58
20	68	68	85	57
21	70	68	85	57
22	69	67	83	57
23	69	67	83	58
24	67	65	81	57
25	67	65	81	57
26	67	67	83	57
27	67	67	83	57
28	67	67	83	57

¹ ThOD_NO3 of test item: 2.569 mg O₂/mg test item

² ThOD_NH4 of sodium benzoate: 1.666 mg O₂/mg reference item

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

In a Manometric Respirometry Test according to OECD TG 301 f and EU Method C.4-D the test item was determined to be readily biodegradable within the 10-day-window and after 28 days (73% based on ThODNH4 and 67% based on ThODNO3).

Executive summary:

The test item was investigated for its ready biodegradability in a Manometric Respirometry Test according to OECD TG 301 f and EU Method C.4-D over a period of 28 days. The biodegradation of the test item (101.8 mg/L) was followed by the oxygen uptake of the microorganisms (activated sludge rom the aeration tank of a domestic waste water treatment plant) during exposure. Simultaneously, a procedure control (containing the reference item sodium benzoate, 1 replicate), a blank control (containing test medium and inoculum, 2 replicates) and a toxicity control (containing both the test item and the reference item, 1 replicate) were performed. In result, the reference item sodium benzoate was sufficiently degraded to 85% after 14 days and to 83% after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used. In the toxicity control containing both, the test item and the reference item sodium benzoate, 63% (ThODnh4)biodegradation was noted within 14 days and 60% (ThODnh4) biodegradation after 28 days of incubation (60% and 57% based on ThODNO3). According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days. The mean biodegradation of 10% of the test item was reached at day 3 (ThODNO3). At the end of the 10-day window at day 13, the mean degradation of the test item was 67% (ThODNO3) and therefore the 10 day window criterion was passed. The mean biodegradation at test end after 28 days was 67% (ThODNO3) and 73% (ThODNH4). The nitrate concentration in the controls after 28 days of incubation was 1.982 mg/L (mean). The nitrate concentration in the test item treated vessels was 0.026 mg/L (LOQ mean). Hence, a nitrification occurred. In the case of a nitrification, or transformation of ammonium to nitrate the degradation of the test item was 73% after 28 days. In conclusion, the test item is regarded to be readily biodegradable according to OECD criteria. All validity criteria of the guidelines were fulfilled.

Description of key information

In a Manometric Respirometry Test according to OECD TG 301 f and EU Method C.4-D the test item was determined to be readily biodegradable within the 10-day-window and after 28 days (73% based on ThODNH4 and 67% based on ThODNO3) (reference 5.2.1 -1).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The test item was investigated for its ready biodegradability in a Manometric Respirometry Test according to OECD TG 301 f and EU Method C.4-D over a period of 28 days. The biodegradation of the test item (initial concentration: 101.8 mg/L) was followed by the oxygen uptake of the microorganisms (activated sludge from the aeration tank of a domestic waste water treatment plant) during exposure. Simultaneously, a procedure control (containing the reference item sodium benzoate, 1 replicate), a blank control (containing test medium and inoculum, 2 replicates) and a toxicity control (containing both the test item and the reference item, 1 repliate) were performed. In result, the reference item sodium benzoate was sufficiently degraded to 85% after 14 days and to 83% after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used. In the toxicity control containing both, the test item and the reference item sodium benzoate, 63% (ThODnh4)biodegradation was noted within 14 days and 60% (ThODnh4) biodegradation after 28 days of incubation (60% and 57% based on ThODNO3). According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days. The mean biodegradation of 10% of the test item was reached at day 3 (ThODNO3). At the end of the 10-day window at day 13, the mean degradation of the test item was 67% (ThODNO3) and therefore the 10 day window criterion was passed. The mean biodegradation at test end after 28 days was 67% (ThODNO3) and 73% (ThODNH4). The nitrate concentration in the controls after 28 days of incubation was 1.982 mg/L (mean). The nitrate concentration in the test item treated vessels was 0.026 mg/L (LOQ mean). Hence, a nitrification occurred. In the case of a nitrification, or transformation of ammonium to nitrate the degradation of the test item was 73% after 28 days. In conclusion, the test item is regarded to be readily biodegradable according to OECD criteria. All validity criteria of the guidelines were fulfilled (reference 5.2.1 -1).