AAA reaction product

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:

2003-11-10 to 2004-02-17

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study performed in acordance to guideline with no deviations

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Principles of method if other than guideline:

NA

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Test material form:

liquid: viscous

Details on test material:

- Name of test material (as cited in study report): DEA/ACID anhydride reaction product

- Physical state: highly viscous amber liquid

- Composition of test material, percentage of components:
Monomers: <17-35% (9-16% diethanolamine; 2-8% tetrahydrophthalic acid; 5-11% trimellitic acid; <0.1% tetrahydrophthalic anhydride; <0.8% trimellitic anhydride)
Dimers/trimers: <24-45%
Polymers: <10-25%
Not removable water: 5-15%

- Lot/batch No.: 200501.UN2810

- Expiration date of the lot/batch: september 2003

- Stability under test conditions: stable under storage condition

- Storage condition of test material: in the refrigerator in the original container away from direct sunlight

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
NA

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

The study was performed with aerobic activated sludge from a wastewater treatment plant (ARA Ergolz II, Füllinsdorf, Switzerland) treating predominantly domestic wastewater. The sludge was washed twice with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized aliquot of the final sludge suspension 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 (±10%) dry material per liter. 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 per liter (dry weight basis). The diluted activated sludge was used as inoculum to give a final concentration of 30 mg dry material per liter.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

ca. 100 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 testing guidelines.
- Additional substrate: NA
- Solubilising agent (type and concentration if used): NA
- Test temperature: 22 °C, maintained with a built-in thermostat and checked once per week
- pH: Prior to test start, the pH was measured in each test flask before the addition of the activated sludge inoculum. At the end of incubation, the pH was measured again in each test flask. The pH measured in all flasks at the start of the test was in the range of 7.3 to 7.4. At the end of exposure (Day 28), the pH values were between 7.2 and 7.9.
- pH adjusted: no
- CEC (meq/100 g): No information
- Aeration of dilution water: Yes
- Suspended solids concentration: The sludge was washed twice with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized aliquot of the final sludge suspension 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 (±10%) dry material per liter. 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 per liter (dry weight basis). The diluted activated sludge was used as inoculum to give a final concentration of 30 mg dry material per liter.
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: The test flasks (500-mL Erlenmeyer flasks, labeled with all necessary information to ensure unmistakable identification) were incubated under continuous stirring in a SAPROMAT D12 (Voith GmbH, Heidenheim, Germany).
- Number of culture flasks/concentration: two/concentration
- Method used to create aerobic conditions: See below
- Method used to create anaerobic conditions: NA
- Measuring equipment: Oxygen consumption was recorded manually by taking a daily reading at least each working day.
- Test performed in closed vessels due to significant volatility of test substance: Yes
- Test performed in open system: No
- Details of trap for CO2 and volatile organics if used: The biodegradation process consumes the dissolved oxygen in the liquid and generates CO2. The CO2 is adsorbed by soda lime and the total pressure decreases in the airtight test flasks. The pressure drop is detected and converted into an electrical signal by means of an electrode type manometer. The consumed oxygen is replaced by electrolytically generated oxygen from a copper sulfate solution.

SAMPLING
- Sampling frequency: one per day for 28 days
- Sampling method: measurement of COD
- Sterility check if applicable: NA
- Sample storage before analysis: No

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, two
- Abiotic sterile control: yes, one
- Toxicity control: yes, one
- Procedure control: yes, two

TEST CONCENTRATIONS
- The amounts of AAA reaction product were directly weighed into the test flasks. No emulsifiers or solvents were used but ultrasound dispersion was employed for ten minutes to obtain a suspension of the test item as homogeneous as possible. For the dosage of the reference item, a stock solution containing 251 mg sodium benzoate per 100 mL of test water was prepared. From this, aliquots of 10 mL were added to the corresponding test flasks. To each flask (with the exception of the abiotic control) activated sludge was added. Finally, the flasks were made up to a volume of 250 mL with test water. The reference item sodium benzoate was tested simultaneously under the same conditions as AAA reaction pproduct, and functioned as a procedure control.

STATISTICAL METHODS: NA

Reference substance

Reference substance:

other: Sodium benzoate

Results and discussion

Preliminary study:

NA

Test performance:

Test performed in accordance to guideline where reference substance and controls (toxicity, abiotic, inoculum, procedure) responded appropriately.

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

53

Sampling time:

28 d

Details on results:

The percent biodegradation was calculated based on its chemical oxygen demand (COD) of 1.39 mg O2/mg test AAA reaction product. The biochemical oxygen demand (BOD) of AAA reaction product in the test media significantly increased from Day 4 until test termination after 28 days. At the end of the 28-day incubation period, the mean biodegradation of AAA reaction product amounted to 53%. Consequently, AAA reaction product was found to be partly biodegradable under the conditions of the test within 28 days. However, the pass level for ready biodegradability (biodegradation of at least 60% of the COD in a 10-day window within the 28-day period of the test) was not reached. The manometric measurement gives no possibilities of identifying which components (monomers, dimers, trimers, polymers) of the AAA reaction product were degraded during the 28-day incubation period.

BOD5 / COD results

Results with reference substance:

The percent biodegradationof the reference item sodium benzoatewas calculated based on the theoretical oxygen demand of 1.67mg O2/mg (ThOD). In the procedure controls, the reference item degraded by an average of 86% by exposure Day 14, thus confirming suitability of the activated sludge. At the end of the test (Day 28), the reference item degraded by an average of 92%.

Any other information on results incl. tables

AAA reaction product:

The percent biodegradation was calculated based on its chemical oxygen demand (COD) of 1.39 mg O₂/mg test AAA reaction product. The biochemical oxygen demand (BOD) of AAA reaction product in the test media significantly increased from Day 4 until test termination after 28 days. At the end of the 28-day incubation period, the mean biodegradation of AAA reaction product amounted to 53%. Consequently, AAA reaction product was found to be partly biodegradable under the conditions of the test within 28 days. However, the pass level for ready biodegradability (biodegradation of at least 60% of the COD in a 10-day window within the 28-day period of the test) was not reached. The manometric measurement gives no possibilities of identifying which components (monomers, dimers, trimers, polymers) of the AAA reaction product were degraded during the 28-day incubation period.

Reference substance (positive control):

The percent biodegradationof the reference item sodium benzoatewas calculated based on the theoretical oxygen demand of 1.67mg O₂/mg (ThOD). In the procedure controls, the reference item degraded by an average of 86% by exposure Day 14, thus confirming suitability of the activated sludge. At the end of the test (Day 28), the reference item degraded by an average of 92%.

Toxicity control:

The percent biodegradation in the toxicity control containing both AAA reaction product and the reference item, was calculated based on the COD of AAA reaction product and the ThOD of the reference item. In the toxicity control, the biochemical oxygen demand over the 28‑day exposure period was similar to the sum of the cumulative BOD of AAA reaction product and of the reference item. Within 14 days of exposure, a biodegradation of 65% was observed. Thus, according to the test guidelines, AAA reaction product had no inhibitory effect on activated sludge microorganisms because biodegradation in the toxicity control was >25% within 14 days.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

AAA reaction product was investigated for its ready biodegradability in a manometric respirometry test over 28 days based on OECD301 F. At the end of the 28-day incubation period, the mean biodegradation of AAA reaction product amounted to 53%, hence AAA reaction product was found to be partly biodegradable under the conditions of the test within 28 days. Further, the pass level for ready biodegradability (biodegradation of at least 60% of the COD in a 10-day window within the 28-day period of the test) was not reached.

Executive summary:

AAA reaction product was investigated for its ready biodegradability in a manometric respirometry test over 28 days based on OECD301 F. The percent biodegradation of AAA reaction product was calculated based on the chemical oxygen demand (COD) of 1.39 mg O₂/mg AAA reaction product.

The biochemical oxygen demand (BOD) of AAA reaction product in the test media significantly increased from Day 4 until test termination after 28 days. At the end of the 28-day incubation period, the mean biodegradation of AAA reaction product amounted to 53%. Consequently, AAA reaction product was found to be partly biodegradable under the conditions of the test within 28 days.

Overall, the pass level for ready biodegradability (biodegradation of at least 60% of the COD in a 10-day window within the 28-day period of the test) was not reached.

In the toxicity control, containing both AAA reaction product and the reference item (sodium benzoate), no inhibition of the biodegradation was determined. Thus, AAA reaction product had obviously no inhibitory effect on the activity of activated sludge microorganisms. In the procedure controls, the reference item (sodium benzoate) degraded by a naverage of 86%until exposure Day 14 and reached an average biodegradation of 92%by the end of the test (Day 28), thus confirming suitability of the activated sludge.