ELDEW PS-203

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:

22.02.1999 to 25.03.1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(1992)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

(1992)

GLP compliance:

yes (incl. QA statement)

Remarks:

RCC Ltd., Environmental Chemistry & Pharmanalytics Division, CH-4452 Itingen (Switzerland)

Test material

Test material information

Constituent 1

Details on test material:

- Name of test material (as cited in study report): Eldew PS-203
- Physical state: pale yellow, oily liquid
- Analytical purity: 100%
- Purity test date: not reported
- Lot/batch No.: 808010
- Expiration date of the lot/batch: 31.03.2000
- Storage condition of test material: test material was stored at room temperature (ca. 20°C), away from direct sunlight

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Ajinomoto Co., Inc., 15-1, Kyobashi 1-chome, Chuo-ku, Tokyo 104-8315 Japan//Batch No.: 808010
- Expiration date of the lot/batch: 31.03.2000
- Purity test date: not reported

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: stored at room temperature at about 20°C, away from direct sunlight

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge was collected from the wastewater treatment plant ARA Ergolz II (Füllinsdorf, Switzerland) treating domestic waste.
- Preparation of inoculum for exposure: The sludge was washed by centrifugation, the supernatant liquid phase was decanted and the solid material resuspended in tap water. This procedure was repeated twice. A homogenized aliquot of the final sludge was weighed, thereafter dried and the ratio of wet to dry weight was calculated. Based on this ratio, calculated amounts of wet sludge were suspended in test water to obtain a concentration equivalent to 4 g/L dw. During holding the sludge was aerated at room temperature until use. Prior to use the sludge was diluted with test water to a concentration of 1 g/L dw. A defined volume of this diluted activated sludge was added to the test flasks to obtain a final concentration of 30 mg/L suspended solids.
- Pretreatment: no
- Concentration of sludge: 30 mg/L suspended solids

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

104 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: according to guideline
- Additional substrate: no
- Solubilising agent (type and concentration if used): not used
- Test temperature: 22°C
- pH: 7.5-7.6
- pH adjusted: no
- Aeration of dilution water: not reported
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Sapromat
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: The sludge was aerated at room temperature until use.
- Measuring equipment: Sapromat
- Test performed in closed vessels: yes
- Details of trap for CO2: The CO2 generated by the biodegradation process was adsorbed by soda lime

SAMPLING
- Sampling frequency: Oxygen consumption was recorded manually by taking a daily reading at least each working day
- Sample storage before analysis: no

CONTROL AND BLANK SYSTEM
- Inoculum blank: performed
- Abiotic sterile control: performed
- Toxicity control: performed
- Other: procedural control performed

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

77

Sampling time:

28 d

BOD5 / COD results

BOD5 / COD

Key result

Parameter:

COD

Value:

1.15 mg O2/g test mat.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

The test item proved to be readily biodegradable but failing the 10-d-window criterion (77% biodegradation after 28 d of incubation at test substance concentrations of twice 104 mg/L). No degradation of the test item occurred in the abiotic control. The functional control reached the pass level > 60% after 14 d. In the toxicity control containing both test and reference item 57% biodegradation based on oxygen consumption occurred within 14 d thus indicating that the test item was not inhibitory at the concentration tested.

Executive summary:

The ready biodegradation of the the test item was investigated in a study conducted according to OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test) and EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test) over a period of 28 days and using activated sludge as inoculum collected from a sewage treatment treating domestic wastewater. The biodegradation rate was determined by measurement of oxygen consumption. Inoculum blank, procedural/functional control with the reference substance sodium benzoate, and toxicity control using 104 mg/L test item and 100 mg/L reference compound were performed.

 

This study is regarded as reliable without restriction and satisfies the guideline requirements for ready biodegradation.

 

The test item proved to be readily biodegradable but failing the 10-d-window criterion (77% biodegradation after 28 d of incubation at test substance concentrations of twice 104 mg/L). No degradation of the test item occurred in the abiotic control. The functional control reached the pass level > 60% after 14 d. In the toxicity control containing both test and reference item 57% biodegradation based on oxygen consumption occurred within 14 d thus indicating that the test item was not inhibitory at the concentration tested.