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Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Mar 14 2019 to June 20, 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report date:
2019

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
3-sec-[C15-18-(branched and linear)-alk-2-enyl]pyrrolidine-2,5-dione
EC Number:
701-350-3
Molecular formula:
Not possible to assign, UVCB
IUPAC Name:
3-sec-[C15-18-(branched and linear)-alk-2-enyl]pyrrolidine-2,5-dione
Test material form:
liquid
Details on test material:
- Appearance: brown liquid
- Storage: room temperature, in the dark
Specific details on test material used for the study:
Test material is a UVCB

Test solutions

Vehicle:
no
Details on test solutions:
The test solution for the study was made up of 4 test groups listed below:

The test mixtures was made up of 2 sets of solutions; the first solution contained the test substance, inoculum, synthetic sewage feed and deionized water while the second solution contained the test substance, synthetic sewage feed and deionized water.

The blank control was made up of 2 sets of solutions; the first solution contained inoculum, synthetic sewage feed, and deionized water while the second solution contained inoculum, synthetic sewage feed, ATU and deionized water.

The reference mixtures was made up of 2 sets of solutions; The first solution contained reference substance, inoculum, synthetic sewage feed, and deionized water, while the second solution reference substance, inoculum, synthetic sewage feed, ATU and deionized water.

Abiotic control ontained Test substance, synthetic sewage feed and deionized water.

Test organisms

Test organisms (species):
activated sludge
Details on inoculum:
Activated sludge obtained from Aeration tank of Datansha Sewage Treatment Plant of Guangzhou with batch number: IAs20190513-1 was used for the study.

Treatment: Coarse particles and impurities were removed from the sludge, then re-suspended in chlorine-free tap water. The activated sludge suspension concentration was determined. Before the study, the sludge suspension concentration was adjusted to 3.0 g/L, and was cultivated, 50 mL of synthetic sewage feed per litre of activated sludge was fed and aerated under the test temperature of 20°C±2°C. The pH value was determined as 7.12 before used.

Study design

Water media type:
other: Deionized water
Limit test:
yes
Total exposure duration:
3 h

Test conditions

Test temperature:
20.6°C - 2 l .9°C
pH:
pH values of each group at the start and the end of the test were in the range of 7.4 5 - 7. 60 and 7. 66 - 7.99.
Details on test conditions:
The test was perfonned at a temperature within the range 20°C±2°C.

The test solutions were aerated with 1 L test vessels inserted into the outlet pipe. The reference substance, test substance, synthetic sewage feed, ATU and deionized water were added into the corresponding test vessels, respectively. The blank controls were prepared in the meantime. After starting the test, 250 mL of activated sludge suspensions were respectively added into each test vessel in tum, with a final volume of 500 mL, aerating and agitating to stay suspending. After the exposure times of three hours, the above test solutions were transferred to 500 mL bottles, then the dissolved oxygen concentrations of each test group and the test temperatures were detennined and recorded. The pH values of each test solution at the start and end of the test were determined.
Reference substance (positive control):
yes

Results and discussion

Effect concentrations
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L

Any other information on results incl. tables

Results of the range-finding test (Total oxygen uptake)

 Test Substance

(mg/L)

 Replicate

Initial DO

(mg/L)

Initial DO caculation

(mg/L)

 Terminal DO

for calculation  

(mg/L)

 Timer Intervals (S)

Specific oxygen

Uptake rate [mg/(g.h)]

 Inhibition (%)  Average (%)
 10  1  8.18  4.44  2.04  150  38.40  -6.5  -
 100  1  8.42  5.20  2.05  210  36  0.2  -
 1000  1  8.43  4.33  1.91  180  32.27  10.5  
 1000  2  8.50  4.81  1.94  210  32.80  9.1  7.3
 1000  3  8.42  4.56  1.92  180  35.20  2.4  
                        3h-EC50(mg/L) >1000

Results of the range-finding test (Abiotic control)

  

Test Substance

(mg/L

   Replicate   

Initial DO

(mg/L)

  

Initial DO caculation

(mg/L)

  

Terminal DO

for calculation  

(mg/L)

  Timer Intervals (S)   

Specific oxygen

Uptake rate [mg/(g.h)]

  Average [mg/(L.h)]
     1000    1  8.68  8.68  8.69  420  -0.1   0     
 2  8.68  8.69  8.69  420  0
 3  8.67  8.69  8.69  420  0

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Under the present test conditions, the 3h-EC50 of the test substance for the total oxygen uptake was higher than 1000 mg/L.
Executive summary:

The study was conducted to determine the EC50 value of the respiration Inhibition of the test substance on activated sludge. The study was conducted in accordance with OECD 209 guidelines and GLP. The test mixture contained the test substance, inoculum, synthetic sewage feed and deionized water. A blank control, reference mixtures and abiotic control were used in the study. Test substance had exposure concentrations of 10 mg/L, 100 mg/L and 1000 mg/L (three replicates) and the abiotic control had a concentration of 1000 mg/L in three replicates. After an exposure time of three hours, the test results showed that the 3h-EC50 of the test substance for the total oxygen uptake was higher than 1000 mg/L. The average of oxygen uptake rates of the abiotic control was 0 mg/(L·h), which revealed that there was no obvious abiotic oxygen consumption during the study period. The test temperature were in the range of 20.8°C - 21.5°C during the test, and the pH values of test mixtures at the start and the end of the test were in the range of 7.41 - 7.48 and 7.49 - 7.61, the pH values of a biotic control at the start were in the range of 7.40 - 7.41, and the end of the test were in the range of 4.98 - 5.1.

The absence of inhibition of oxygen consumption by the test substance in the range-finding test demonstrated that a definitive test was unnecessary.

Therefore, under the present test conditions, the 3h-EC50 of the test substance for the total oxygen uptake was > 1000 mg/L.

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