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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Reference
Endpoint:
biodegradation in water: sewage treatment simulation testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
September 2015
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
OECD Guideline 303 A (Simulation Test - Aerobic Sewage Treatment. A: Activated Sludge Units)
Version / remarks:
Only Preliminary test was done
GLP compliance:
no
Remarks:
only Preliminary test
Radiolabelling:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Reasons for the selection of the study system
Activated sludge from the sewage plant at Hildesheim is well suited as it comprises mostly municipal sewage and hardly industrial chemical waste.

Source
Municipal sewage treatment plant, D-31137 Hildesheim

Pretreatment
The activated sludge was washed with chlorine free tap water, concentrated and afterwards maintained in an aerobic condition by aeration at room temperature until it was used. Based on the dry matter, the starting concentration was adjusted to 2.5 ± 0.5 g/L DW (nominal value).
Duration of test (contact time):
25 d
Parameter followed for biodegradation estimation:
DOC removal
% Degr.:
97.8
Parameter:
DOC removal
Sampling time:
23 d
Transformation products:
no
Volatile metabolites:
no

Biodegradation of Organic Medium (DOC)

During acclimatization the activated sludge units had stabilized and biodegradation of the DOC of the organic medium became efficient (> 80 % after 2 days).

Due to variations in the quality and composition of the organic medium, the biodegradation decreased below 80 % periodically for 7 days. The decrease had no influence on the biodegradation efficiency, the unit worked efficiently throughout the test.

 

Elimination of Antimussol ZJ based on Specific LC-MS/MS Analysis

After the activated sludge units had stabilized, the dosage of the test item was started (September 2, 2015). Influent (stock solution) and effluent samples were analysed by LC- MS/MS.

The elimination of the test item was calculated based on influent and effluent concentrations. The plateau was considered to have been reached on day 19 after application of the test item.

 

The mean elimination was 98.6 % (calculated day 19 to day 23 after test item application).

 

Biodegradation of Antimussol ZJ based on Specific LC-MS/MS Analysis

The primary degradation was calculated based on the total influent load, the total effluent load and the test item load adsorbed onto the activated sludge.

Primary biodegradation started as well directly after starting the application of Antimussol ZJ. The mean primary degradation during the plateau phase was 97.8 % (Table 4).

 

Important note:Due to the preliminary character of this study, missing values had to be estimated. This was done for the effluent load by using the last measured value for dateswithout measurements. For the total surplus sludge load, the mean value of the measurements was used. Therefore, when evaluating the biodegradation value of this study, these assumptions have to be kept in mind.

Validity criteria fulfilled:
yes
Conclusions:
The primary degradation was calculated based on the total influent load, the total effluent load and the test item load adsorbed onto the activated sludge.
Primary biodegradation started as well directly after starting the application of Antimussol ZJ. The mean primary degradation during the plateau phase was 97.8 %
Executive summary:

The elimination and primary biodegradation of the test item Antimussol ZJ in an activated sludge unit was determined over a test period of 25 days according to OECD guideline 303 A. The study was conducted from 2015-08-31 to 2015-09-25 at the Dr.U.Noack-Laboratorien, 31157 Sarstedt, Germany.

The primary biodegradation was monitored by the decline of Antimussol ZJ in the effluent and activated sludge.

During acclimatization the activated sludge units had stabilized and biodegradation of the DOC of the organic medium became efficient (> 80 % after 2 days).

Due to variations in the quality and composition of the organic medium, the biodegradation decreased below 80 % periodically for 7 days. The decrease had no influence on the biodegradation efficiency, the unit worked efficiently throughout the test.

The nominal concentration of the test item stock solution was 500 mg/L. The stock solution was dosed at a constant rate of 0.25 pL/h into the activated sludge unit, resulting in a nominal influent concentration of 200 pg/L.

The elimination was calculated based on the influent and effluent concentrations. The primary degradation was calculated based on the total influent load, the total effluent load and the test item load adsorbed onto the activated sludge.

The amounts of Antimussol ZJ eliminated from the aqueous phase are summarized in Table 3. The mean elimination was 98.6 % (calculated day 19 to day 23 after test item application).

Primary biodegradation started as well directly after starting the application of Antimussol ZJ. The mean primary degradation during the plateau phase was 97.8 % .

Important note: Due to the preliminary character of this study, missing values had to be estimated (Effluent load, surplus sludge load). Therefore, when evaluating the biodegradation value of this study, these assumptions have to be kept in mind.

Description of key information

The primary degradation was calculated based on the total influent load, the total effluent load and the test item load adsorbed onto the activated sludge.

Primary biodegradation started as well directly after starting the application of Antimussol ZJ. The mean primary degradation during the plateau phase was 97.8 %

Key value for chemical safety assessment

Additional information