2-butoxyethyl benzoate

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:

2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to OECD TG 301F and in accordance with the Principles of Good Laboratory Practices (GLP

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Principles of method if other than guideline:

not applicable

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

2-butoxyethyl benzoate

EC Number:

226-685-8

EC Name:

2-butoxyethyl benzoate

Cas Number:

5451-76-3

Molecular formula:

C13H18O3

IUPAC Name:

2-butoxyethyl benzoate

Test material form:

other: variable coloured liquid

Details on test material:

- Name of test material (as cited in study report): 2-butoxyethyl benzoate (Butyl Cellosolve™ Benzoate)
- Physical state: clear liquid
- Analytical purity: 99.2%
- Lot/batch No.: 20130443-19
- Expiration date of the lot/batch: 02 April 2016
- Storage condition of test material: Ambient

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
not applicable

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

A fresh sample of activated sludge was collected from the aeration tank of the Longhua Wastewater Treatment Plant in Shanghai which treats predominantly domestic sewage by an anaerobic-aerobic process(A/O). The activated sludge was kept aerobic by aeration until used (non-aeration during transport from the wastewater treatment plant to the laboratory was kept to a minimum).
Sludge treatment: Before use, the activated sludge was passed through a 0.5 mm sieve to remove coarse particles. The sludge was washed with mineral medium by settling the sludge in a graduated cylinder, decanting the supernatant liquid, replacing with fresh mineral medium, aerating, and settling. The above washing process was repeated 3 times, then the sludge was centrifuged one time(1500rpm, 4 °C, 10 minutes), and the supernatant liquid was decanted. A small amount (about 0.4 g) of the concentrated sludge was weighed, and then dried at 105 °C for 1h to calculate the moisture. The dry weight of sludge was 13.24%. Sludge suspension: Based on the dry weight, the amount of wet sludge was calculated and suspended in mineral medium to attain a mixed liquor suspended solids level of 3g/L. The final concentration of the activated sludge in the test medium was 30mg/L.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

22 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

50.6 mg/L

Based on:

ThOD/L

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Reference substance

Reference substance:

benzoic acid, sodium salt

Remarks:

Alfa Aesar (Purity: 99%; Lot: BCBH8216V)

Results and discussion

Preliminary study:

not applicable

Test performance:

The mean BOD of the inoculum blanks was 13.85mg O2/L in 28 days, which was less than 60mg/L, meeting the guideline requirement. The pH values of the solution in test substance flasks were in the range of 6.92-7.14, which met the requirement of pH 6.0-8.5 of the test substance solution. The difference between replicate values of the removal of the test substance during 28d test period was less than 20%.
The mean biodegradation of the reference substance(Sodium benzoate) was 97% by Day 14, reaching the pass level of the ready biodegradation test(>60% within 14 days).
The biodegradation percent of the toxicity control was 94% by day 14, ~25% ThOD, which met the guideline requirement.
Thus, the test was considered valid.

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

91

Sampling time:

12 d

Details on results:

The mean BOD of the inoculum blanks was 13.85mg O2/L in 28 days, which was less than 60mg/L, meeting the guideline requirement. The pH values of the solution in test substance flasks were in the range of 6.92-7.14, which met the requirement of pH 6.0-8.5 of the test substance solution. The difference between replicate values of the removal of the test substance during 28d test period was less than 20%.
The mean biodegradation of the reference substance(Sodium benzoate) was 97% by Day 14, reaching the pass level of the ready biodegradation test(>60% within 14 days).
The biodegradation percent of the toxicity control was 94% by day 14, ~25% ThOD, which met the guideline requirement.
Thus, the test was considered valid.

BOD5 / COD results

BOD5 / COD

Parameter:

BOD5

Value:

13.85 other: mg/l

Results with reference substance:

The mean biodegradation of the reference substance(Sodium benzoate) was 97% by Day 14, reaching the pass level of the ready biodegradation test(>60% within 14 days). The biodegradation percent of the toxicity control was 94% by day 14, ~25% ThOD, which met the guideline requirement.

Any other information on results incl. tables

None

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The mean BOD of the inoculum blanks was 13.85mg O2/L in 28 days, which was less than 60mg/L, meeting the guideline requirement. The pH values of the solution in test substance flasks were in the range of 6.92-7.14, which met the requirement of pH 6.0-8.5 of the test substance solution. The difference between replicate values of the removal of the test substance during 28d test period was less than 20%.
The mean biodegradation of the reference substance(Sodium benzoate) was 97% by Day 14, reaching the pass level of the ready biodegradation test(>60% within 14 days).
The biodegradation percent of the toxicity control was 94% by day 14, ~25% ThOD, which met the guideline requirement.
The test substance 2-Butoxyethyl benzoate was readily biodegradable under the present test conditions.

Executive summary:

The study was conducted according to the guidelines of "OECD, Guidelines for the Testing of Chemicals. Ready Biodegradability 301 F: Manometric Respirometry Test, 1992."

Under specific experimental conditions, the ready biodegradability of 2-Butoxyethyl benzoate (DOWM20140410-0882) was determined in a 28-day dissolved oxygen depletion test using activated sludge from a domestic waste water treatment plant.

The tested concentration of test substance was 22.00 mg/L (i.e. 50.60mg ThOD/L). The concentration of sludge inoculum in the test system was 30mg/L, and the tested concentration of sodium benzoate used as reference substance was 100mg/L (i.e.167.00mg ThOD/L). A toxicity control was also included.

During the test, the temperature was maintained at 21.7-22.3 °C. The mean total O2 uptake in the inoculum blanks at the end of the test was less than 60mg O2/L in 28 days meeting the guideline requirement. Biodegradation of the reference substance (sodium benzoate) reached the pass level of the ready biodegradation test(>60% within 14 days), achieving 97% biodegradation by Day 14. The difference of extremes between replicate values of the removal of the test substance during the 28 -d test period was less than 20%. The results of the toxicity control showed that the test substance met the criteria for not being inhibitory to the microbial inoculum. Thus, the test is valid.

Results showed that under the experimental conditions, biodegradation of the test substance attained an average of 91% at Day 12 (10 -d window) and 101% at Day 28, exceeding the readily biodegradable criterion of >60% in 10 day window.

Therefore, the test substance can be considered to be readily biodegradable under the experimental conditions according to this test method.