Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
February 2013
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP study following the current guideline, but quoted with reliability 2 due to the read across.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
Description: orange colored powder
Purity: 99.7%
Expiry date: 24 December 2013
Storage conditions: room temperature in the dark

Sampling and analysis

Analytical monitoring:
not required

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
Method: the test item was dispersed in approximately 200 mL of deionized reverse osmosis water and subjected to ultrasonication for approximately 15 minutes followed by magnetic stirring for 24 hours in order to maximize the dissolved test item concentration.

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
A mixed population of activated sewage sludge micro-organisms was obtained from the aeration stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK which treats predominantly domestic sewage.

Study design

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

Test conditions

Hardness:
no data
Test temperature:
20°C +/- 2°C
pH:
7.3 to 7.7 at the beginning of the test
7.4 to 8.2 after 3 hours
Dissolved oxygen:
2.9 to 5.7 mg O2/ L
Nominal and measured concentrations:
10, 40, 160, 640 and 2500 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 500 mL conical flask
- Aeration: The mixture was aerated with clean, oil-free compressed air via narrow bore glass tubes at a rate of approximately 0.5 – 1 liter per minute.
- No. of vessels per concentration (replicates): 3 replicates
- Biomass loading rate: suspended solids concentration: 3 g/L

TEST MEDIUM / WATER PARAMETERS: deionized reverse osmosis water containing less than 1 mg/L dissolved organic carbon

EFFECT PARAMETERS MEASURED : oxygen concentration rate

TEST CONCENTRATIONS
- Range finding study: 10, 100 and 1000 mg/L, gave toxicity from 10 mg/L
- Test concentrations: chosen to obtain EC10 and EC50: 10, 40, 160, 640 and 2500 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.:
14 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
vanadium
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
2 719 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
vanadium
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Results with reference substance (positive control):
EC10, 3 hours: 0.24 mg/L
EC50, 3h : 6.3 mg/L

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
The coefficient of variation of oxygen uptake in the control vessels was 7.0% and the specific respiration rate of the controls was 27.67 mg oxygen per gram dry weight of sludge per hour.
Executive summary:

Following a preliminary range-finding test, activated sewage sludge was exposed to aqueous dispersions of V2O5 at concentrations 10, 40, 160, 640 and 2500 mg/L (three replicates of each) for a period of 3 hours at a temperature of 20 ± 2 °C with the addition of a synthetic sewage as a respiratory substrate.

When expressed as vanadium, the test item concentrations were 5.6, 22.4, 89.6, 358.4 and 1400 mg V/L.

The effect of the test item on the respiration of activated sewage sludge gave an EC 10 value of 25 mg/L and an EC 50 value of 4865 mg/L after 3 hours exposure expressed as test item content.

When expressed as vanadium, the effect of the test item on the respiration of activated sewage sludge gave an EC 10 value of 14 mg V/L and an EC 50 value of 2719 mg V/L after 3 hours exposure.