Lithium acetate

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:

from 2015-07-29 to 2015-08-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot No.: 09406DE

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Species: Activated sludge, microorganisms from a domestic waste water treatment plant
- Source of activated sludge: The (controlled) activated sludge was supplied by the sewage plant for domestic sewage in Balatonfüred, Hungary, on 22 July 2015 (7 days before the test).
- Preparation of inoculum for exposure: The activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in isotonic saline solution and again centrifuged. This procedure was repeated twice. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 5 g dry material per litre was mixed with test water (see below) and then aerated under test conditions (for 7 days) until use. The pH of the activated sludge inoculum after preparation was 7.32, just before use: 7.44. A pH adjustment of activated sludge inoculum was not performed.
- Pretreatment: Pre-conditioning consisted of aerating (2 L/minute) activated sludge (in mineral medium, reconstituted water) for 7 days at the test temperature. During the aeration the cell count of inoculum was checked as follows: the viability of the cultured sludge was determined by plating 0.1 mL of the different, usually 10-3, 10-4 and 10-5 dilutions of cultures on nutrient agar plates. The viable cell number of the cultures was determined by these plating experiments by manual colony counting. The approximately cell count of aerated inoculum fell in the range of 10^8/L; therefore on the day of the test this inoculum was diluted adequately with reconstituted water to reach the necessary cell concentration (guideline proposal of 10^4-10^6 approx. cells/L). After preparation, the sludge was filtered through cotton wool. Pre-conditioning improved the precision of the test methods by reducing blank values.
The inoculum was not pre-adapted to the test chemical.
- Concentration of sludge: 5 g dry material per litre
- Initial cell/biomass concentration: 10^4 - 10^6 cells/L

Duration of test (contact time):

28 d

Initial conc.:

3 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Accroding to guideline
- Test temperature: During test: 20 ± 2 °C
- pH: 7.51
- pH adjusted: no
- Continuous darkness: yes
- Aeration of dilution water: Aeration until use
- Oxygen Concentration of the test Water: About 8-9 mg/L (was measured at the start of the test and found to be 8.43 mg/L)

TEST SYSTEM
- Culturing apparatus: Winkler bottles (300 mL, coded) with special neck and glass stoppers.
- Number of culture flasks/concentration:
20 (+2 reserve) bottles containing the test item and inoculum
20 (+2 reserve) bottles containing the reference item and inoculum (procedure control)
20 (+2 reserve) bottles containing only inoculum (inoculum control)
20 (+2 reserve) bottles containing the test item, reference item and inoculum (toxicity control)
- Method used to create aerobic conditions: Aeration system
- Measuring equipment: Oxygen and pH meter with appropriate O2 and pH electrode, Thermometer, Moisture analyser

CONTROL AND BLANK SYSTEM
- Inoculum blank: Only filtered inoculum was added to the aqueous test medium.
- Toxicity control: Test and reference item stock solutions (80-80 mL) were mixed into the aqueous test medium (ad. 8000 mL) corresponding to the test item concentration of 3.0 mg/L [chosen based on the calculated ThODNH4 of the test item and the preliminary experiment] and to 3.0 mg/L concentration of the reference item.
- Procedure Control: Based on the theoretical oxygen demand (ThODNH4) of Sodium benzoate (1.67 mg O2 per mg) (details on calculation are given in the guidelines), at the start of the test a stock solution of Sodium benzoate (80 mL) was mixed into (ad. 8000 mL) the aqueous test medium (corresponding to 3.0 mg/L reference item, respectively a ThODNH4 of about 3.0 x 1.67= 5.01 mg O2/L).

Reference substance:

benzoic acid, sodium salt

Test performance:

The purpose of this study was to determine the ready biodegradability of the test item lithium acetate anhydrous. The test item was exposed to activated sludge from the aeration tank of a domestic waste water treatment plant for 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

Key result

Parameter:

% degradation (O2 consumption)

Value:

80.9

Sampling time:

28 d

Key result

Parameter:

BOD5

Value:

> 0.51 - < 0.61 other: mg O2/mg test.mat.

Results with reference substance:

The reference item sodium benzoate was sufficiently (nearly entirely) degraded to a mean of 96.3 % after 14 days, and to a mean of 97.7 % after 28 days of incubation, based on ThODNH4. The percentage biodegradation of the reference item confirms the suitability of the used activated sludge inoculum.

Percentage Biodegradation at Different Time Intervals during the Exposure Period of 28 Days

Treatment	Concentration [mg/L]	Flask No.	Percent of biodegradation after n days of exposure
			1	2	3	5	7	11	14	21	28
Test item	3.0	1a	-0.2	33.5	31.9	52.2	71.8	76.2	77.6	82.8	80.0
		1b	0.5	39.7	36.1	62.5	78.6	78.0	77.3	80.0	81.7
		Mean	0.2	36.6	34.0	57.4	75.2	77.1	77.4	81.4	80.9
Reference item	3.0	2a	-0.7	47.1	50.4	66.8	96.6	91.0	93.8	96.0	96.4
		2b	0.1	49.9	49.0	74.8	95.8	95.8	98.8	96.0	99.0
		Mean	-0.3	48.5	49.7	70.8	96.2	93.4	96.3	96.0	97.7
Toxicity control	Test item: 3.0 Reference item: 3.0	4a	-0.3	42.5	44.7	44.9	70.4	74.4	75.7	76.3	81.3
		4b	0.4	46.1	46.1	58.1	74.1	76.5	76.1	76.0	83.3
		Mean	0.1	44.3	45.4	51.5	72.2	75.5	75.9	76.2	82.3

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under the conditions of the present study, the test item is considered to be ready biodegradable, since the pass level for ready biodegradability is removal of 60 % ThODNH4 in a 10-day window.

Executive summary:

Lithium acetate was tested in a closed bottle test according to OECD guideline 301 D and EU method C.4 E.The purpose of this study was to determine the ready biodegradability of the test item lithium acetate anhydrous. The test item was exposed to activated sludge from the aeration tank of a domestic waste water treatment plant for 28 days. The biodegradation was followed by the oxygen uptake of the microoganisms during exposure. The test item lithium acetate was investigated at the concentration of 3.0 mg/L.

Under the test conditions ready biodegradation of this test item was noticed. The percentage biodegradation of lithium acetate reached a mean of 80.9 % after 28 days based on its ThODNH4. The 10-day window criterion for ready biodegradation was unequivocally fulfilled, 60 % biodegradation of the test item (based on its ThODNH4) was observed before the 7th day of the test. The test item is considered to be ready biodegradable, since the pass level for ready biodegradability is removal of 60 % ThODNH4 in a 10-day window.
The percentage biodegradation of the reference item confirms the suitability of the used activated sludge inoculum.
According to the test guidelines the test item can be assumed as not inhibitory at the applied concentration level on the activated sludge microorganisms because the degradation in the toxicity control group was higher than 25 % within 14 days.

Description of key information

Under the conditions of the present study, the test item is considered to be ready biodegradable, since the pass level for ready biodegradability is removal of 60 % ThODNH4 in a 10-day window.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Lithium acetate was tested in a closed bottle test according to OECD guideline 301 D and EU method C.4 E.The purpose of this study was to determine the ready biodegradability of the test item lithium acetate. The test item was exposed to activated sludge from the aeration tank of a domestic waste water treatment plant for 28 days. The biodegradation was followed by the oxygen uptake of the microoganisms during exposure. The test item lithium acetate, anhydrous was investigated at the concentration of 3.0 mg/L.

Under the test conditions, ready biodegradation of this test item was noticed. The percentage biodegradation of Lithium acetate reached a mean of 80.9 % after 28 days based on its ThODNH4. The 10-day window criterion for ready biodegradation was unequivocally fulfilled, 60 % biodegradation of the test item (based on its ThODNH4) was observed before the 7th day of the test. The test item is considered to be ready biodegradable, since the pass level for ready biodegradability is removal of 60 % ThODNH4 in a 10-day window.
The percentage biodegradation of the reference item confirms the suitability of the used activated sludge inoculum.
According to the test guidelines the test item can be assumed as not inhibitory at the applied concentration level on the activated sludge microorganisms because the degradation in the toxicity control group was higher than 25 % within 14 days.