Sodium methyl sulphate

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:

2016-10-20 - 2016-11-18

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 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Sodium methyl sulphate

EC Number:

208-142-7

EC Name:

Sodium methyl sulphate

Cas Number:

512-42-5

Molecular formula:

CH4O4S.Na

IUPAC Name:

sodium methyl sulphate

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: KIRSCHAZ2-00182
- Expiration date of the lot/batch: 07 July 2018
- Purity: 99.1 %
STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Storage at room temperature
- Stability under test conditions: stable

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Municipal activated sludge from the wastewater treatment plant of Mannheim, Germany.
The inoculum was collected on 19 October 2016 from the aeration tank of the plant. A suitable aliquot of the activated sludge suspension was sieved by a finely woven mesh with a mesh size about 1 mm. To reduce the content of inorganic carbon in the blank controls the activated sludge was aerated with carbon dioxide free air for about 24 hours at 22 ± 2° C.

- Preparation of inoculum for exposure: At the day of exposure the suspension was washed one time with drinking water.
Therefore the aeration was stopped and the sludge was allowed to settle. After settling the supernatant was discarded and the remaining sludge suspension was filled up with drinking water and the concentration oft the sludge was adjusted to 6.0 g/L dry weight. Aliquots of 7.5 mL were added to the test vessels to obtain an activated sludge concentration of 30 mg/L dry weight

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

20 mg/L

Based on:

TOC

Initial test substance concentration 2

Initial conc.:

ca. 220 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: acccording to the guideline
- Test temperature: 22 ± 2° C (The test temperature was temporary just below 20 °C. An impact to the test result can be excluded)
- pH: 7.3 - 6.6
- Aeration of dilution water: the aeration was performed with carbon dioxide free air at a flow of approximately 800 mL per hour.

TEST SYSTEM
- Culturing apparatus: 2 L incubation bottles
- Number of culture flasks/concentration: 2

- Details of trap for CO2: The bottles were connected to two serial scrubbing bottles (total volume 250 mL) filled with 100 mL 0.05 mol sodium hydroxide solution for the adsorption of
carbon dioxide from biodegradation processes. Usually twice a week the Total Inorganic Carbon (TIC) values of the adsorption solutions of the first trap were determined and used
for the calculation of the produced carbon dioxide. After each sampling the second trap was moved forward and the new trap with fresh sodium hydroxide solution was placed
into the second position. Each trap was analyzed separately.


SAMPLING
- Sampling frequency: Usually twice a week

CONTROL AND BLANK SYSTEM
- Inoculum blank (BC): 2
- test substance assays (TS): 2
- nhibition control test assay (IH): 1
- reference substance assay (RS) 1

Reference substance

Reference substance:

aniline

Results and discussion

% Degradation

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 90 - <= 100

Sampling time:

28 d

Remarks on result:

other: readily, but failing 10d-window

BOD5 / COD results

Results with reference substance:

Degree of biodegradation of the reference substance after 14 days: 85 % CO2/ThCO2

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

The conclusion that Sodium methyl sulfate was not readily biodegradable in this
carbon dioxide evolution test based on the quantitative determination of the formed
carbon dioxide in the test substance assays by comparison with the calculated maximal
theoretical carbon dioxide production.
The required pass level for ready biodegradability within a ten day window was not
reached.
The degree of biodegradation at the end of the ten day window was approx. 53 %
CO2/ThCO2.
The degree of biodegradation after an exposure period of 28 days was 90-100 %
CO2/ThCO2 in this test.
The degree of biodegradation was calculated as mean of the values from two test assays
at the end of exposure.
Based on the rate of biodegradation of 90-100 % CO2/ThCO2 at the end of exposure the
test substance can be evaluated as biodegradable in this test.
The results in this study are consistent with all relevant validity criteria and the test is valid
according to the test guideline of this study. No deviations from the test guidelines or other
incidents occurred during the course of the reported test, which may have influenced the
results