Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study according to OECD 209

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Physical state: Solid/ red
- Storage condition of test material: Ambient at room temperature

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
The test substance was added in the required amounts according to the test concentrations directly to the test vessels with about 234 mL deionized water. 16 mL synthetic medium were dosed to each test vessel with test substance afterwards. The pH-values in all test vessels were checked. An adjustment was not necessary.

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- Laboratory culture: Activated sludge from the municipal wastewater treatment plant of Mannheim, Germany was collected from the aeration tank of the plant
- Preparation of inoculum for exposure: The activated sludge suspension was sieved with a fine woven mesh (mesh size about 1 mm). This suspension was pre-aerated over night at room temperature. At the next day the sludge suspension was washed once with drinking water and the suspension was adjusted to 3 g/L dry matter
- Pretreatment: None
- Initial biomass concentration: 1.5 g/L dry mass

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h

Test conditions

Test temperature:
20.7 – 21.1 °C
Dissolved oxygen:
Oxygen concentration during aeration: > 2 mg/L
Oxygen concentration immediately before measurement: > 7 mg/L
Nominal and measured concentrations:
1000, 500, 250, 125, 62.5 mg/L as nominal concentration based on test substance without correction of purity.
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer-flasks (nominal volume 250 mL)
- Type (delete if not applicable): closed
- Aeration: incubation was started by aeration of the test vessels with pressure air
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates):2
- No. of vessels per vehicle control (replicates):0

OTHER TEST CONDITIONS
- Adjustment of pH: no

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Justification for using less concentrations than requested by guideline:
- Test concentrations: 62.5, 125, 250, 500, 1000 mg/L
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol

Results and discussion

Effect concentrationsopen allclose all
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
other: EC20
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Results with reference substance (positive control):
The EC50 of 3,5-dichlorophenol is in the range of 5 - 30 mg/L

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The inhibition of the degradation activity of activated sludge is not anticipated when introduced in appropriate low concentrations.