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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:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2011-11-01 - 2011-11-29
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: according OECD 303A Guideline and GLP. Read-across justification is given in the read-across document attached in IUCLID Section 13.

Data source

Reference
Reference Type:
other: Preliminary results
Title:
Unnamed
Year:
2011
Report Date:
2011

Materials and methods

Test guideline
Qualifier:
according to
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
Type:
Constituent
Details on test material:
Chemical Name : Glycine, N-coco acyl derivs., sodium salts
Radiolabelling:
no

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge from the sewage plant at Hildesheim is well suited as it comprises mostly municipal sewage and hardly industrial chemical waste (industrial chemical waste: 30 - 33 %, referring to BOD).

- Preparation of inoculum for exposure: The activated sludge was maintained in an aerobic condition by aeration at room temperature until it was used. Calculated starting concentration of dry matter was about 3 g/L.

Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
300 µg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
TEST CONDITIONS
- Volume of test solution/treatment: Cstock = 3 g/L in methanol, freshly prepared at least every 7 days. Dosed at a constant rate of 0.05 L/h
- Composition of medium: Organic medium: Mixture of domestic sewage and synthetic sewage with 100 mg C/L
- Additional substrate: Synthetic sewage was prepared according to OECD 303 A and used for DOC adjustment of domestic sewage if necessary.
- Test temperature: 20 - 25 °C
- pH: 7.5 +/- 0.5 (no adjustments were made)
- pH adjusted: no
- Suspended solids concentration: Initial dry weight content: 3.0 +/- 0.5 g/L
- Continuous darkness: Low light conditions


TEST SYSTEM
- Apparatus: Activated sludge units consisting of an aeration vessel (3L) and a separator (2.5 L)
- Number of culture flasks/concentration: 1
- Method used to create aerobic conditions: continuous aeration
- Measuring equipment:
Oxygen, pH-value, Multi 340 (WTW)
Temperature
Pumps Membrane piston pumps ProMinent® gamma/ 4-W
(PROMINENT DOSIERTECHNIK GMBH, Heidelberg)
Precision syringe pumps, KD SCIENTIFIC and HARVARDAPPARATUS
Aeration Membrane pump MP500 (BEHR LABOR-TECHNIK)
DOC Multi N/C 3000 ANALYTIK JENA AG

- Test performed in closed vessels due to significant volatility of test substance: No
- Test performed in open system: Yes


SAMPLING
- Sampling frequency:
Type and Frequency of Measurements
(exclusive test item analysis)

Parameter Frequency
Influent volumes 3x per week
Removed sludge volume Daily
DOC of the effluents Weekdays during acclimatisation, daily during steady state phase
DOC of the influent Every new batch
Oxygen concentration, temperature, pH value in the aeration vessel At least twice per week
Suspended solids Daily


- Sample storage before analysis: Samples were stored at -20 +/- 2 °C before preparation and at room temperature after sample preparation, if necessary.



CONTROL AND BLANK SYSTEM
- Inoculum blank: An activated sludge unit with methanol treatment (without test item) was used as control.
- Abiotic sterile control: No
- Toxicity control: No



Results and discussion

Test performance:
The system was started with the conditions described above.
• Set-up of the test units
• Inoculation with activated sludge
• Dosage of sewage (organic medium)
• Sludge adhering to the walls of the activated sludge units was resuspended
• After the system had stabilized and the removal of DOC of the sewage was efficient (> 80 %) the test item solution (control: methanol) was applied.
• Sampling and measurements as given above
• Calculation of ultimate biodegradation of the organic medium, elimination/adsorption and primary biodegradion of the test item
• Completion of the study after a sufficient degree of elimination and the plateau was reached (> 90 %).

% Degradation
% Degr.:
94.9
Parameter:
test mat. analysis
Sampling time:
28 d
Remarks on result:
other: median of all samples
Transformation products:
not measured
Evaporation of parent compound:
no
Volatile metabolites:
no
Residues:
no

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The elimination was 99 % for the test item Hostapon SG. The maximum primary biodegradation was 94.9 % (sewage and sewage sludge). Sorption to activated sludge was 4.1%.
Executive summary:

The elimination and biodegradation of the test item Hostapon SG in an activated sludge unit was determined over a test period (plateau phase) of 28 days according to OECD guideline 303 A. The study was conducted from 2011 -11 -01 to 2011 -11 -29 at the Dr.U.Noack-Laboratorien, 31157 Sarstedt, Germany .

During acclimatisation the activated sludge units were inoculated with activated sludge. The DOC elimination of the organic medium reached a degradation rate > 80 % already after 2 days. The dosage of the test item was started after an acclimatisation period of 3 days.

The nominal concentration of the test item stock solution was 3 g/L. The stock solution was dosed at a constant rate of 0.05 mL/h into the activated sludge unit, resulting in a nominal influent concentration of 300 µg/L.

Specific analysis Hostapon SG was carried out via LC-MS/MS. The concentrations in the influent (organic medium and stock solution), effluent and activated sludge were determined. The LOQ for the organic medium was 30 µg/L. For activated sludge the LOQ was 55.6 µg.

One day after starting the application of Hostapon SG the elimination was already 99 % Furthermore, primary biodegradation started directly after starting the application of Hostapon SG. During the plateau phase, a primary biodegradation of 94.9 % was reached (median of all samples).

The elimination was 99 % for the test item Hostapon SG. The maximum primary biodegradation was 94.9 % (sewage and sewage sludge).The elimination was 99 % for the test item Hostapon SG. The maximum primary biodegradation was 94.9 % (sewage and sewage sludge). Sorption to activated sludge was 4.1%.