Alkanoic acid and polyoxomolybdate borate alkanoate clusters

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 31, 2017 - March 10, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

July 17, 1992; §14 corrected July 26, 1993

Deviations:

yes

Remarks:

Some unexpected values were recorded for one of the reference item replicates : an air leak occured, the data observed were unusable. According to OECD 301F, tthe data corresponding to the other reference item flask was only used.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Test material form:

liquid: viscous

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Laboratory preparation:
A filtration through a fine sieve (about 1 mm) was performed in order to remove coarse particles. After removal of any coarse particles, the sludge was washed by decantation in a mineral medium until sludge was considered free from excess substrate or inhibitor.

Inoculum pre-conditioning:
Pre-conditioning consisted in aerating sludge (in mineral medium) for 5-7 days before the test and at the test temperature.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST ITEM PREPARATION
According to the sponsor, the test item is poorly soluble in water; it was introduced directly in the test Flasks. The test item was tested at 100 mg/L in mineral medium.
The test medium will be the mineral medium, a weakly saline aqueous medium.

PROTOCOL
Principle:
A measured volume of inoculated medium containing a known concentration of the test item (100 mg/L) as the nominal sole source of Carbon, was stirred in a closed vessel at a constant temperature up to 28 days.
Microbial respiration consumes O2 and releases CO2 which was absorbed by soda lime pellets present in the headspace of flasks. This produces a decrease in pressure in the flask proportional to the amount of oxygen taken up by the microbial population during biodegradation, which was expressed as a percentage of ThOD (Theoretical Oxygen Demand).
Allowance was made for the endogenous activity of the inoculum by running parallel blanks with inoculum but without the test item.
Furthermore, in order to check the procedure, a reference item control (sodium benzoate 60.2 mg/L + inoculum) and a toxicity control (sodium benzoate + inoculum + test item) were run in parallel.
The pH of the contents was measured at the start and the end of the experiment.

Test design:
The medium was prepared from concentrated stock solutions in ultrapure water as described in the guideline.

Incubation:
The test was performed in darkness between 20 to 24°C (constant temperature ±1°C).

MATERIAL AND METHOD
Inoculum preparation:
Sample site = Water treatment plant 'STEP de Lille', 33290 Blanquefort (France) - Tank 2
Date of sampling = January 26, 2017
Inoculum physico-chemical characteristic at the beginning of the test:
Suspended solid = 2.76g/L
pH = 6.4
Dissolved oxygen = 86 mg/L
Activated sludge preparation:
1. Filtration through a 1 mm sieve
2. 3 successive decantations into mineral medium
3. Activated sludge aeration during 5 days

Preparation of the test solutions:
The test item was weighed and introduced directly in each flasks to obtain a nominal concentration of 100 mg/L.
A solution of sodium benzoate was produced: weighing of 200.15 mg in 200 mL (final volume) mineral medium.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Preliminary study:

The theorical Oxygen Demand is 2.444 mg O2 per mg of test item.

Test performance:

All validity criteria were successful.

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

0.59

St. dev.:

0.6

Sampling time:

28 d

Remarks on result:

other: See 'Remarks'

Remarks:

The test item contains no nitrogen according to the elemantary analysis, the evaluation of biodegradation has to be based as ThOD(NH4).

Details on results:

The degradation for the 10-day window failed.
The degradation rate of the test item reached 0.00% to 1.19%, following the ThODNH4, after 28 days of incubation.
According to the OECD guideline 301F, the test item cannot be considered readily biodegradable.

Biodegradation of the reference item: “Sodium benzoate”:
The reference item “Sodium benzoate” was degraded up to 88.69% after 28 days.
Therefore, it confirms the suitability of the used aerobic sludge inoculum.

Biiodegradation of the Toxicity Control:
A biodegradation of 25.87% and 32.84% after 14 days of incubation was noted in the Toxicity control (containing both of the test item and the reference item).
At the end on the test, 28 days of incubation, the results were respectively 32.76% and 40.88%.
Therefore, the test item was not inhibitory at the tested concentration on the aerobic activated sludge micro organism because degradation was >25% within 14 days (validity criterion).

BOD5 / COD results

Results with reference substance:

The reference item “Sodium benzoate” was degraded up to 88.69% after 28 days.
Therefore, it confirms the suitability of the used aerobic sludge inoculum.

Any other information on results incl. tables

Percentage (%) Biodegradation during 28 days:

Time (days)	Reference item - Sodium benzoate	Toxicity control		Test item
Measuring system	7	8	11	23	14	15	Average
0	0.00	0.00	0.00	0.00	0.00	0.00	0.00
1	45.00	13.49	13.90	0.00	0.00	0.00	0.00
2	56.27	16.37	16.37	0.00	0.00	0.00	0.00
3	62.79	18.26	18.26	0.00	0.00	0.95	0.32
4	67.08	19.07	19.51	0.00	0.00	0.00	0.00
5	72.66	21.95	21.95	0.00	0.00	0.95	0.32
6	78.25	23.60	23.60	0.38	0.00	0.38	0.25
7	80.68	24.28	24.28	0.19	0.00	0.76	0.32
8	82.54	24.41	24.82	0.00	0.00	0.38	0.13
9	84.37	24.94	25.35	0.00	0.00	0.00	0.00
10	86.63	25.20	25.60	0.00	0.00	0.00	0.00
11	86.17	25.47	26.57	0.19	0.00	0.19	0.13
12	86.63	25.60	28.74	0.00	0.00	0.38	0.13
13	87.56	25.87	31.21	0.19	0.00	0.76	0.32
14	88.96	25.87	32.84	0.19	0.00	0.19	0.13
15	88.56	26.34	33.59	0.19	0.00	0.00	0.06
16	88.09	26.20	34.62	0.57	0.00	0.00	0.19
17	88.69	26.09	35.95	0.00	0.00	0.00	0.00
18	88.69	26.67	37.11	0.57	0.00	0.00	0.19
19	88.69	26.67	37.98	0.57	0.00	0.57	0.38
20	88.76	26.69	38.29	0.76	0.00	0.19	0.32
21	88.29	26.84	38.74	1.15	0.00	0.00	0.38
22	88.89	27.30	39.20	1.15	0.57	0.00	0.57
23	89.42	27.75	39.65	1.53	0.38	0.38	0.76
24	88.96	28.48	39.80	1.34	0.76	0.19	0.76
25	88.96	28.77	40.09	1.34	0.19	0.76	0.76
26	88.96	29.94	40.67	1.34	0.76	0.76	0.95
27	88.49	30.96	40.83	1.72	0.57	1.15	1.15
28	88.69	32.76	40.88	1.19	0.57	0.00	0.59

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Under conditions of OECD guideline 301F, the test item cannot be considered readily biodegradable.

Executive summary:

The aim of this study was to determine the ready biodegradability of the test item, according to the OECD 301F guideline, within an experimental period of 28 days by respirometric method.

The amount of oxygen taken up by the microbial population during the biodegradation of the test item (corrected by blank inoculum, run in parallel) was determined from the change in pressure in apparatus and will be expressed as percentage of theoretical Oxygen Demand (ThOD).

All the validity criteria were successful

The degradation for the 10-day window failed. The degradation rate of the test item reached 0.00% to 1.19%, following the ThODNH4, after 28 days of incubation. According to the OECD guideline 301F, the test item cannot be considered readily biodegradable.

The reference item “Sodium benzoate” was degraded up to 88.69% after 28 days. Therefore, it confirms the suitability of the used aerobic sludge inoculum.

A biodegradation of 25.87% and 32.84% after 14 days of incubation was noted in the Toxicity control (containing both of the test item and the reference item). At the end on the test, 28 days of incubation, the results were respectively 32.76% and 40.88%. Therefore, the test item was not inhibitory at the tested concentration on the aerobic activated sludge micro organism because degradation was >25% within 14 days (validity criterion).