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Environmental fate & pathways

Biodegradation in water: screening tests

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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:
1997
Report date:
1997

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
GLP compliance:
yes

Test material

Constituent 1
Reference substance name:
Yellow MGi 1301
IUPAC Name:
Yellow MGi 1301
Test material form:
solid

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Duration of test (contact time):
35 d
Initial test substance concentrationopen allclose all
Initial conc.:
140 mg/L
Based on:
DOC
Remarks:
nominal value
Initial conc.:
27.5 mg/L
Based on:
DOC
Remarks:
measured value
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
DOC removal
Reference substance
Reference substance:
aniline

Results and discussion

% Degradation
Parameter:
% degradation (DOC removal)
Value:
52
Sampling time:
35 d

Any other information on results incl. tables

Expressed as percentage DOC removal, average degradation was only 8 % after 27 days, 46 and 48 % after 28 and 29 days, respectively, and 52 % after 35 days of exposure to activated sludge from a domestic waste water treatment plant.

Likewise, in the abiotic control (flask no. 6) containing the test article and sterile medium (without inoculum) practically no DOC-removal was noted during the first 27 days of exposure. Starting on exposure day-27 the DOC concentration decreased from 27.2 mg/l to 17.3 mg/l on day-35. Expressed as percentage DOC-removal, values in the range from 0 to 9 % were noted during the first 27 days of exposure, and 44, 50 and 42 % were noted after 28, 29 and 35 days of exposure, respectively without activated sludge under abiotic conditions.

These results indicate that YELLOW MGi 1301 was biotically degraded by 52 % after 35 days of exposure, and that the sudden start of biodegradation after 28 days was additionally facilitated by the spontaneous abiotic degradation of the test article under the present test conditions.

ln the procedure controls (flasks no. 3 and 4) containing the reference compound Aniline and inoculum, Aniline was readily biodegraded by an average of 92 % within 14 days of exposure, and by 96 % by exposure day-28; thus confirming suitability of the activated sludge.

ln the toxicity control containing the test article (40.5 % as DOC), the reference compound (59.5 % as DOC) and inoculum, the initial DOC concentration of 32.6 mg/l measured on day-0 decreased by 64 % within 14 days of exposure; thus, according to the test guidelines the test article can be assumed to not be inhibitory to activated sludge because degradation was > 35 % within 14 days.

Applicant's summary and conclusion

Conclusions:
Ready Biodegradabilty (35 d) = 52 % DOC removal