[No public or meaningful name is available]

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:

June 5, 2020 to September 17, 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Sulfonic acids, C16-alkane hydroxy and C16-alkene, potassium salts

Cas Number:

2210238-42-7

IUPAC Name:

Sulfonic acids, C16-alkane hydroxy and C16-alkene, potassium salts

Test material form:

cream / paste

Remarks:

This sample was obtained from the original liquid form by removing water.

Details on test material:

Identification: Internal Olefin Sulfonate
Description: pale yellow paste

Specific details on test material used for the study:

Expiry date: January 24, 2023
Storage conditions: room temperature in the dark, kept in airtight container
Storage place: desiccator

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic, non-adapted

Details on inoculum:

Inoculum: Activated sludge from domestic sewage treatment plant
Source: Sewage treatment plant mainly handling domestic wastewater in Kanagawa
Date of collection: June 4, 2020
Culture condition: The inoculum was maintained in an aerobic state until used in the test.
Mixed liquor suspended solids (MLSS): 1600 mg/L

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

30 mg/L

Based on:

act. ingr.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

Degradability study conditions
Apparatus
　Thermostatic water bath: Water bath shaker MM-10, Taitec Corp.
Conditions
　Temperature: 22 土 2°c
　Exposure period: 28 days
　Test vessel: 1 L Erlenmeyer flask, glass (covered with aluminum foil)
　Test volume: 500 mL
Concentration:
Test substance: 30.0 mg/L
Reference substance: 60.0 mg/L
Inoculum: 30 mg/L
Light: Fluorescent light

Test bottle contents and preparation of test solutions
　Outline of the test solution was shown below. The test substance solution*1 or reference substance solution*2 were added to the mineral medium in test vessels. Then inoculum was added after the pH was measured.
pH meter: F-52, HORIBA, Ltd.
*1 Preparation of test substance solution:
In ultra-pure water, 82.0 mg of the test sample (50.0 mg as the test substance after purity correction) was dissolved by ultrasonication for approximately 1 minute, and filled up to 50 mL to make a test substance solution of 1000 mg/L.
*2 Preparation of reference substance solution:
In ultra-pure water, 100 mg of the reference substance was dissolved, and filled up to 100 mL to make a reference substance solution of 1000 mg/L.

Bottle No.1 and 2 (Test suspension-1 and 2)
test substance solution 15 mL, mineral medium 500 mL*3, Inoculum 9.4 mL*4
Bottle No.3 (Procedure control)
reference substance solution 30 mL, mineral medium 500 mL*3, Inoculum 9.4 mL*4
Bottle No.4 and 5 (Inoculum blank-1 and 2)
mineral medium 500 mL*3, Inoculum 9.4 mL*4

*3 The total volume of the test substance solution or reference substance solution and the inoculum was held fixed at 500 mL.
*4 The inoculum addition= 30 (mg/L) + MLSS (mg/L) x 500 (mL)

Management during exposure period
　At the start and end of exposure, the water temperature in the thermostatic water bath was measured with the following apparatus. During the exposure period, the test solution volume, the set temperature of the thermostatic bath, and that the test vessel was being shaken under fluorescent light were checked once a day except on holidays when no sampling was performed. At the end of exposure, the dissolved oxygen concentration (DO) of the test solution was measured with the following apparatus to confirm that the test solution was aerobic.
Apparatus
　Thermo recorder: Wireless RTR-71(No.4), T&D
　DO meter: 5100(No.1), YSI/Nanotech Inc.

Evaluation of test results
Equations for calculation of degradability
　Degradability based on DOC was calculated for each bottle by the following equation.
　Degradability (%) = [1 - (DOCs-DOCb) / (DOCs0-DOCb0)] x 100
　Where DOCs: DOC (mgC/L) in the [Inoculum + test substance] or the [Inoculum +
reference substance] at day x
DOCb: Average of DOC (mgC/L) in the [Control blank] at day x
DOCsO: DOC (mgC/L) in the [Inoculum + test substance] or the [Inoculum +
reference substance] at day 0
DOCbO: Average of DOC (mgC/L) in the [Control blank] at day 0

Judgment of degradability
　The pass levels for readily degradability were shown below.
　　·　Degradability based on DOC is 70% or more.
　　·　The pass value (the attainment of 70% biodegradation) has to be reached in a 10-d 　　　　
window*1 within the 28-d period of the test. The 10-d window begins when the degree of
biodegradation has reached 10% DOC and must end before day 28 of the test.
*1 The 10 days immediately following the attainment of 10% biodegradation.

Validity of the test
　The test was considered valid if the following criteria were met.
　1) The degradability of reference substance based on the DOC exceeds 70% after 14 days.
　2) The difference between the maximum and minimum values of the degradability in the
[Inoculum + test substance] is less than 20%.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Test performance:

All of the validity criteria given in the guideline were fulfilled and hence the test was judged valid.

% Degradation

Key result

Parameter:

% degradation (DOC removal)

Value:

97

Sampling time:

28 d

Details on results:

Factors which might have affected the reliability of the test results
　There was no specific factor which might have affected the reliability of the test results.

DO measurement
　At the end of exposure, the DO values were 8.83 and 8.90 mgO2/L for the [Inoculum + test substance]-1 and 2 (bottle 1 and 2), 8.84 and 8.86 mgO2/L for the [Control blank]-1 and 2 (bottle 4 and 5), 8.81 mgO2/L for the [Inoculum + reference substance] (bottle3), respectively.

Degradability based on the DOC
　The DOC in the [Inoculum + test substance]-! and 2 at day 28 were 1.7 and 2.0 mgC/L, and the DOC in the [Control blank]-1 and 2 were 1.2 and 1.3 mgC/L. The degradabilities based on the DOC at day 28 were calculated to be 97% and 96% for the [Inoculum + test substance] -1 and 2, respectively.
　The degradabilities based on the DOC at day 14 was calculated to be 97% for the [Inoculum + reference substance].

Any other information on results incl. tables

Result of DOC measurement (mgC/L)

Bottle No.	Sample description		Day
			0	5	7	14	21	28
1	Test suspension-1 [Inoculum＋test substance]-1	a1	17.16	8.92	4.59	2.95	2.62	1.66
		a2	17.16	8.72	4.65	3.01	2.63	1.79
		Ave., A	17.2	8.8	4.6	3.0	2.6	1.7
2	Test suspension-2 [Inoculum＋test substance]-2	b1	17.21	9.67	4.76	2.95	2.14	1.82
		b2	17.39	9.90	4.69	3.01	2.23	2.09
		Ave., B	17.3	9.8	4.7	3.0	2.2	2.0
3	Procedure control [Inoculum＋reference substance]	p1	36.88	3.30	3.78	2.22	2.03	1.97
		p2	36.91	3.55	3.65	2.20	2.10	2.18
		Ave., P	36.9	3.4	3.7	2.2	2.1	2.1
4	Inoculum blank-1 [Control blank]-1	c1	1.25	1.04	1.31	0.89	0.94	1.14
		c2	1.27	1.44	1.54	1.18	1.24	1.29
		Ave., C	1.3	1.2	1.4	1.0	1.1	1.2
5	Inoculum blank-2 [Control blank]-2	d1	1.26	1.41	1.33	0.99	1.07	1.18
		d2	1.31	1.75	1.44	1.22	1.06	1.34
		Ave., D	1.3	1.6	1.4	1.1	1.1	1.3
		Ave. (C, D), I	1.3	1.4	1.4	1.1	1.1	1.3

 

Degradability (%)

Bottle No.	Sample description		Day
			0	5	7	14	21	28
1	Test suspension-1 [Inoculum＋test substance]-1	D1	0	53	80	88	91	97
2	Test suspension-2 [Inoculum＋test substance]-2	D2	0	48	79	88	93	96
		Ave., (D1, D2)	0	51	80	88	92	97
3	Procedure control [Inoculum＋reference substance]	D3	0	94	94	97	97	98

Equations:

D1 = [1 - (A_x - I_x) / (A₀ - I₀)] × 100

D2 = [1 - (B_x - l_x) / (B₀ - I₀ )] × 100

D3 = [1 - (P_x - I_x) / (P₀ - I₀ )] × 100

A_x, B_x, P_x: DOC (mgC/L) in the [Inoculum + test substance] or the [Inoculum + reference substance] at day x

I_x: Average of DOC (mgC/L) in the [Control blank] at day x

A₀, B₀, P₀: DOC (mgC/L) in the [Inoculum + test substance] or the [Inoculum + reference substance] at day 0

I₀: Average of DOC (mgC/L) in the [Control blank] at day 0

 

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The pass value of 70% biodegradation was considered to be reached at the end of the 10-d window because the biodegradation rate based on the DOC had exceeded 70% at day 7 (Average value: 80%). As the biodegradation rate was over 70% at the end of the 10-d window and the end of the exposure (day 28), these results indicate that the test substance was readily biodegradable under the test conditions.

Executive summary:

METHOD

OECD Guideline for Testing of Chemicals 301A "Ready Biodegradability: DOC Die-Away Test" (1992)

(Study period)

June 5, 2020 to September 17, 2020

(Test bottle contents)

Bottle 1, 2     Test suspension:                   [Inoculum ＋ test substance]-1, 2

Bottle 3         Procedure control:                [Inoculum ＋ reference substance]

Bottle 4, 5     Inoculum blank:                   [Control blank]-1, 2

(test substance: 30.0 mg/L, reference substance: 60.0 mg/L, inoculum: 30 mg/L)

(Measurements)

Dissolved organic carbon (DOC) [measured with a TOC analyzer]

 

RESULTS

Measured values after 28 days

Measurement	[Inoculum ＋test substance]		[Control blank]
	1	2	1	2
DOC, mgC/L	1.7	2.0	1.2	1.3
Degradability, %	97	96	-	-

CONCLUSION

It is concluded that the test substance is readily biodegradable under the conditions of this test.