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Environmental fate & pathways

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:
2001-11-05 to 2002-01-25
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2002

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): T002113
- Physical state: pale yellow solid (powder)
- Analytical purity: 92.9%
- Lot/batch No.: RT002113G3A231
- Expiration date of the lot/batch: 2001-12-01
- Stability under test conditions: results from a hydrolysis pre-experiment (without GLP), indicated that, at a pH of 7, the test item concentration decreased rapidly within two hours by about 50% and thereafter stayed constant for at least five days (RCC Study No. 825265).
- Storage condition of test material: at room tempertature at about 20°C away from direct sunlight
- Other:
* Solubility in water: 120 g/L
* pH in aqueous solution: 3.8 at a concentration of 120 g/L
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: RT00211G3A231
- Expiration date of the lot/batch: 2001-12-01 (retest date)
- Purity test date: no data

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature at about 20°C
- Stability under test conditions: no data
- Solubility and stability of the test substance in the solvent/vehicle: no data

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source: predominantly domestic wastewater treatment plant, ARA Ergolz II, Füllinsdorf, Switzerland
- Storage conditions: During holding, the sludge was aerated at room temperature until use.
- Preparation of inoculum for exposure: The sludge was once washed with tap water by centrifugation, the supernatant liquid phase was decanted, homogenized aliquot of final sludge suspension weighed, dried, and ratio wet to dry weight calculated.
- Pretreatment: Prior to use sludge was diluted to 1 g dw/L for use as inoculum.
- Initial biomass concentration in test:30 mg dry material per liter.
- Water filtered: purified water
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
ca. 100 mg/L
Based on:
test mat.
Initial conc.:
ca. 156 mg/L
Based on:
ThOD
Remarks:
without nitrification
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: test water prepared according to test guidelines. Analytical grade salts were dissolved in purified water to obtain the following stock solutions:
a) KH2PO4 8.50 g/L
K2HPO4 21.75 g/L
Na2HPO4 x 2H20 33.40 g/L
NH4Cl 0.50 g/L
The pH of this solution was 7.4.
b) MgSO4 x 7H2O 22.50 g/L
c) CaCl2 x 2 H2O 36.40 g/L
d) FeCl3 x 6 H20 0.25 g/L
In order to avoid having to prepare solution d) immediately before use, one drop of concentrated HCl per liter was added. To obtain the final test water, 10 mL of stock solution a) and 1 mL each of stock solutions b) - d) were combined and made up to 1000 mL with purified water. The pH was adjusted from 7.7 to 7.4 with diluted hydrochloric acid solution.
- Additional substrate: no
- Test temperature: 22°C
- pH: 7.3-7.8, measured prior to testing in each test flask before addition of inoculum, and again in each test flask at the end of the incubation period
- pH adjusted: yes, from 7.7 to 7.4 with a diluted HCl solution
- Suspended solids concentration: intially 30 mg dw/L
- Continuous darkness: yes

TEST SYSTEM
- Test flasks: 500-mL glass Erlenmeyer flasks , fill-volume 250 mL
- Culturing apparatus: SAPROMAT D12 (Voith GmbH, Heidenheim, Germany)
- Number of culture flasks/concentration: 2
- Measuring equipment: Electro-chemical analysis process
- Oxygen consumption was recorded manually by taking a daily reading at least on each working day.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, two replicates with test substance without inoculum
- Abiotic sterile control: yes, one replicate with test substance and sterilized with mercury dichloride at a concentration of 10 mg/L
- Toxicity control: yes, one replicate with test substance, reference substance, and inoculum
- Procedure control: yes, 2 replicates with reference substance and inoculum
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Key result
Parameter:
% degradation (O2 consumption)
Value:
ca. 0
Sampling time:
28 d
Details on results:
No degradation of the test item occurred within 28 days of incubation. The BOD of the test item was below the range of the inoculum controls. The toxicity controls indicated that the test item did not have an inhibitory effect on the activated sludge microorganisms.

BOD5 / COD results

Results with reference substance:
Average % degradation was 81% by exposure day 14 and 91% by exposure day 28, confirming suitability of the activated sludge.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
A 28-d ready biodegradability test (OECD 301F, manometric respirometry test) using unadapted activated sludge from a predominantly domestic waste water treatment plant indicated no biodegradation of the test substance (initial concentration 100 mg T002113/L). The results of the test can be considered reliable without restriction.