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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
4 July - 7 Aug, 1994
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: done under OECD method and GLP

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guidelineopen allclose all
according to
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
according to
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
GLP compliance:

Test material


Study design

Oxygen conditions:
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
a) Inoculated Nutrient Medium
b) 4mg/l test substance
c) 3mg/l sodium benzoate (C6H5.COONa)
d) 4mg/l test substance + 3mg/l sodium benzoate

Inoculation of stock nutrient medium with activated sludge filtrate at the rate of 1ml inoculum/l performed immediately prior to preparation of the above series.
Duration of test (contact time):
28 d
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
dissolved oxygen concentration
Details on study design:
280ml darkened glass BOD bottles incubated in a water bath at 21±1°C and analysed for dissolved oxygen at 0, 4, 7, 11, 14, 18, 21, 25 and 28 days.
The test substance is considered to have an inhibitory effect on the bacteria if the oxygen demand in series 'd' (above) is 25% less than the sum of oxygen demand in series'b' and 'c' at 14 days.
Reference substance
Reference substance:
other: Sodium benzoate

Results and discussion

Preliminary study:
A-87440.0 may not be termed as readily biodegadeable.
There was no evidence of inhibitory effects.
% Degradation
% degradation (O2 consumption)
Sampling time:
28 d
Details on results:
Cultures containing both test and standard substances combined showed an oxygen depletion value 47% higher than that anticipated on the basis of results from separate cultures at day 14. Therefore, the test substance is not considered to have had an inhibitory effect on sewage bacteria under the test conditions.Points of degradation plot (test substance):
6 % degradation after 4 d
8 % degradation after 7 d
7 % degradation after 11 d
6 % degradation after 14 d
3 % degradation after 18 d
12 % degradation after 21 d
12 % degradation after 25 d
20 % degradation after 28 d

BOD5 / COD results

Results with reference substance:
Sodium benzoate attained 72% biodegradation within 28 days.

Points of degradation plot (reference substance):
70 % degradation after 4 d
70 % degradation after 7 d
72 % degradation after 11 d
65 % degradation after 14 d
67 % degradation after 18 d
71 % degradation after 21 d
64 % degradation after 25 d
72 % degradation after 28 d

Any other information on results incl. tables

As nitrogen was present to a significant extent, at day 28, nitrite and nitrate analyses were performed on the test solutions in order to determine the extent of nitrification. The amount of oxygen uptake due to nitrification processes was not considered to be significant at 0.082 mgO2/l cf. total O2 depletion of 1.225 mgO2/l. Therefore, the Theoretical Oxygen Demand (NH4) of A-87440.0 was used to determine the extent of carbonaceous biodegredation

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
other: not readily biodegradable
The test material attained 20% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the test conditions.