Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1994
Report Date:
1994

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Version / remarks:
29/12/1992
Qualifier:
according to
Guideline:
other: Determination of the water biodegradability of organic chemicals by means of the two-phase air-water closed bottle test. NEN 6515
Version / remarks:
1992
Qualifier:
according to
Guideline:
other: Draft International Standard. Two phase closed bottle test. ISO/TC 147/SC5/WG4 N174
Version / remarks:
1993
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Mixed liquor is obtained from the aeration tank of the waste water treatment plant of Bocholt. This treatment plant is dealing predominantly with domestic sewage. The activated sludge is sampled on 18/10/93 and used on the same day. Before use, the mixed liquor is sieved through a 0.5mm sieve in order to remove large particles, the suspended solids content is determined (4.36 g/L) and the mixed liquor is washed with test medium. Afer settlement of the sludge, the liquid phase is discarded and the solids are resuspended in test medium to obtain a concentration of 3 g/L (= inoculum suspension).
A dilution of 10 ml of the inoculum suspension in 1 litre test medium is made to obtain a suspended solids concentration of 30 mg/l (= inoculated test medium).
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
15.4 mg/L
Based on:
ThOD
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Test temperature: 20-25°C
- pH: 7.5
- pH adjusted: no
- Suspended solids concentration: 30 mg/L

TEST SYSTEM
- Number of culture flasks/concentration: 3
- Measuring equipment:
Oxygen electrode - Range 0 to 10 mg/l with a precision of 1%. Steady-state is reached within 1.5-2 min.
- Method used to create aerobic conditions: air diffuser for 15min, using water-washed air.

SAMPLING
- Sampling frequency: weekly
- Sampling method: After each one-week's incubotion period, the concentration of dissolved oxygen in each bottle is determined. The pH is measured. The medium in each bottle is aerated with an air-diffuser for 15 min. at 20 + 0.5 °C. The bottles are re-stopped and incubated on the shaking device,

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (three replicates)
- Three bottles of the reference substance (aniline)
- Toxicity control: yes (one bottle, 15.5 mg/L test substance/reference substance stock solution)
Reference substance
Reference substance:
aniline

Results and discussion

Test performance:
The total oxygen uptake of the blank bottles after the first week of the test is lower than 3 mg O2 and during the following weeks < 1 mg O2 per week. The percentage degradation of the reference substance aniline is > 60% by day 14.
% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Remarks:
V190110
Value:
-7
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Remarks:
V190110 and aniline
Value:
-3
Sampling time:
28 d
Remarks on result:
other:
Remarks:
This means that the test substance has an inhibitory effect at the tested concentration
Parameter:
% degradation (O2 consumption)
Remarks:
aniline
Value:
80
Sampling time:
28 d

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
V190110 had an inhibitory effect on biodegradation at the tested concentration.