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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Administrative data

Endpoint:
biodegradation in water: sewage treatment simulation testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study, GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1993
Report date:
1993

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 303 A (Simulation Test - Aerobic Sewage Treatment. A: Activated Sludge Units)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: 20% of the pure active substance in water
Details on test material:
- Name of test material: DOPA-Glycinate
Radiolabelling:
no

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on source and properties of surface water:
- Details on collection (e.g. location, sampling depth, contamination history, procedure): Oxidation ditch for domestic sewage treatment, Berkel, The Netherlands
- Laboratory culture: No
- Preparation of inoculum for exposure: Sieving (2 mm) and homogenising

Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Oxidation ditch for domestic sewage treatment, Berkel, The Netherlands
- Laboratory culture: No
- Preparation of inoculum for exposure: Sieving (2 mm) and homogenising

Duration of test (contact time):
25 d
Initial test substance concentration
Initial conc.:
120 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
TEST CONDITIONS
- Composition of medium:
Peptone 6400 mg/L, Meat extract 4400 mg/L, Urea 1200 mg/L, NaCl 280 mg/L, CaCl2 • 2 H2O 160 mg/L, MgSO4 • 7 H2O 80 mg/L,
K2HPO4 • 3 H2O 1120 mg/L
- Additional substrate: None; however, the dilution water (Milli-Q) contained 15–21 mg/l DOC between Dec 09 and Dec 18, 1991; this was corrected for in the calculations
- Test temperature: 18 ± 2°C
- pH: 6.9–7.4 (test unit), 6.6–7.3 (blank unit)
- pH adjusted: no
- Aeration of dilution water: Continuous aeration of the test solutions
- Suspended solids concentration: 2.0–2.5 g/L
- Continuous darkness: yes
- Other: Working-in time: 8 days

TEST SYSTEM
- Culturing apparatus: OECD confirmatory test units, continuous flow activated sludge system
- Number of culture flasks/concentration: 1
- Aeration device: Not specified
- Measuring equipment: OI Model 700 TOC analyser
- Test performed in closed vessels due to significant volatility of test substance: Not relevant


SAMPLING
- Sampling frequency: daily


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes


STATISTICAL METHODS:
Degradation rate according to test guideline.

Results and discussion

% Degradation
% Degr.:
81
St. dev.:
5
Parameter:
DOC removal
Sampling time:
25 d
Transformation products:
not measured

Any other information on results incl. tables

The results indicate a nearly complete removal of the test substance in the coupled unit test. The plateau level was reached in 8 days and the mean degradation percentage was calculated from 10 plateau values to be 81 ± 5%.

Applicant's summary and conclusion

Validity criteria
Validity criteria fulfilled:
yes
Conclusions:
By means of the coupled units test (OECD 303A), DOPA-Glycinate was established to be ultimately biodegradable in sewage treatment plants.
Executive summary:

The degradation of DOPA-Glycinate was simulated in a coupled units test (OECD 303A). The performance of the test deviated from the guideline in several aspects. However, the fact that the inoculum originated from only a single source is considered to be without negative consequences since the microbial activity proved to be adequate. Deviations in the concentration of the synthetic sewage were compensated during dosing. Centrifugation may be considered a sufficiently effective method for removal of particulate matter from the effluent.In conclusion, the deviations from the guideline are considered to be insignificant for the validity of the study.

The DOC fed to the test system by means of the test substance was effectively removed from the test solution. The degradation rate was 81 ± 5% (mean ± SD).

The test substance is known to exhibit microbicidal properties. However, this had apparently no negative effects on the test system, presumably due to the high activity and concentration of the activated sludge.

Since the deviations from the test guideline as discussed above had no significant impact on the outcome of the study, the test is considered to be valid.

By means of the coupled units test (OECD 303A), DOPA-Glycinate was established to be ultimately biodegradable in sewage treatment plants.