3-methylbutanone

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well conducted guideline study conducted under GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

3-methylbutanone

EC Number:

209-264-3

EC Name:

3-methylbutanone

Cas Number:

563-80-4

Molecular formula:

C5H10O

IUPAC Name:

3-methylbutan-2-one

Details on test material:

- Name of test material (as cited in study report): methyl isopropyl ketone
- Substance type: production sample
- Physical state: liquid
- Analytical purity: 99.6%
- Lot/batch No.: TXTXOL
- Storage condition of test material: stored in the original container at room temperature in a dark ventilated cabinet

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Approximately 4 L of activated sludge was collected from the Wareham, Massachusetts Wastewater Treatment Plant which treats primary domestic sewage. Upon arrival at Springborn, the activated sludge was centrifuged at 1000 rpm for 10 minutes. The supernatant (or secondary effluent) was kept and the solids discarded. The resultant secondary effluent was fiitered through coarse filter papei. Following filtration, the first 200 mL of secondary effluent was discarded. The next 500 mL of secondary effluent was retained and aerated. The inoculum was used on the same day as it was prepared.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

2.5 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

6.5 mg/L

Based on:

ThOD/L

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Oxygen-rich water was prepared by bubbling compressed air through water for 20 minutes and the DO measured. The water was aerated for an additional 5 minutes and was allowed to stand overnight at 20 ± 1C prior to test initiation. Nutrient solutions were prepared using the oxygen rich water. The nutrient solutions were aerated in the same manner as the water and stored in a refrigerator until used. Fifty-four industrial 300-mL BOD bottles were prepared for the reference and test substances and the inoculum control blanks; eighteen bottles per treatment, two each for day 0, three per
sampling interval (i.e., days 7, 14, 21 and 28) and an additional four bottles for each treatment. The filled BOD bottles were maintained in a dark environmental chamber, set to maintain a temperature of 22 ± 2 °C. A 2.5 mg/L test substance solution was prepared by adding 15 mg (19 uL) of the test
substance directly into 6 L of mineral media. A 10 mg/mL sodium benzoate stock solution was prepared by adding 1.0111 g (1.001 g as a.i.) of sodium benzoate to a volumetric flask and diluting to a volume of 100 mL with sterile reagent grade water. The theoretical oxygen demand (ThOD) for the test substance was calculated to be 2.60 mg O2/mg test substance. A nominal test substance concentration of 2.5 mg/L was selected as the test concentration. The ThOD for the sodium benzoate was calculated to be 1.67 mg O2/mg sodium benzoate. The nominal sodium benzoate concentration was selected to be 4.0 mg/L. The test solutions were prepared by first adding approximately 3 L of the aerated water by siphon to each of three 9-L bottles, one for the test substance, one for the sodium benzoate and one for the inoculum control blank. Each 9-L bottle then received 6 mL of each of
the four nutrient solutions. The test substance bottle next received 900 uL of the secondary effluent and 19 uL of the test substance, the sodium benzoate bottle received 900 uL of the secondary effluent and 2.4 mL of the 10 mg/mL sodium benzoate stock solution and the inoculum blank bottle received 900 uL of the secondary effluent. Each of the three bottles was then brought to a final volume of 6 L with the aerated water. Immediately after preparation, each solution was siphoned (bubble-free) from the 9-L bottles into the respective series of 18 BOD bottles (for a total of 54 bottles for the three solution types). The bottles were slightly overfilled to eliminate all air bubbles. With the exception of the BOD bottles to be used for day 0 analysis, all bottles were then placed in the environmental chamber and the test was intiated.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (O2 consumption)

Value:

77.2

Sampling time:

7 d

% Degradation 2

Parameter:

% degradation (O2 consumption)

Value:

85.1

Sampling time:

28 d

Details on results:

77.2% degradation of the test substance was observed on day 7 and 85% degradation was observed by test day 28. Degradation in the sodium benzoate test solutions was 76.1 % on day 7 and 84% on day 28 which indicated that the inoculum contained a viable microbial population and that the test procedures used during the study were adequate.

BOD5 / COD results

Results with reference substance:

Degradation in the sodium benzoate test solutions was 76.1 % on day 7 and 84% on day 28.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Executive summary:

Determination of the ready biodegradability of Methyl Isopropyl Ketone following OECD Guideline 301 D (Closed Bottle Test) was conducted under GLP conditions. 77.2% degradation of the test substance was observed on day 7 and 85% degradation was observed by test day 28 therby meeting the defined criteria for being readily biodegradable. The degradation of the reference substance indicated that the inoculum contained a viable microbial population and that the test procedures used during the study were adequate.