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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
Study period:
1988 - 1989
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: well performed OECD study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report Date:
1989

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
not specified
Principles of method if other than guideline:
In the Closed Bottle Test the biodegradation is determined by measuring the O2 consumption of the bacteria and calculation of the ratio of it to the theoretical maximum of O2 demand during total combustion of the test substance. This method is used to test for ready biodegradability. It specifies that the amount of O2 consumed within 14 days after adaptation (when the 10% threshold is exceeded) and at the most 28 days overall must attain 60% of the measured COD (chemical oxygen demand) or of the calculated thOD (theoretical oxygen demand) of the test material in the test batches.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
purity: 99.0 %

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Origin: Sewage treatment plant at Frankfurt am Main-Sindlingen
Type of inoculum: Supernatant from settled domestic sewage sludge
Content of suspended solids: Not determined
Amount used: One drop per one litre of the final volume of the batch
Pre-treatment: No pre-treatment
State of adaption: Not pre-adapted to the test substance or the reference substance.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
50 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
4
Sampling time:
7 d
Parameter:
% degradation (O2 consumption)
Value:
6
Sampling time:
14 d
Parameter:
% degradation (O2 consumption)
Value:
91
Sampling time:
21 d
Parameter:
% degradation (O2 consumption)
Value:
99
Sampling time:
28 d

BOD5 / COD results

Results with reference substance:
O2 consumtion
in % of the COD Time (d)
0 0
78 7
75 14
76 21
69 28

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The substance is readily biodegradable
Executive summary:

The substance was tested for ready biodegradability according to OECD guideline 301 D (Closed Bottle Test) with activated, not adapted sludge from a domestic waste water treatment plant.

During a test period of 21 days the oxygen consumption achieved on average 91 % of the calculated oxygen demand for complete combustion of the added test substance in the batches. The adaptation phase took 14 days. It is defined as the time period until attainment of the 10 % threshold. The "14-days-window" for the biodegradation phase in the closed bottle test was kept. The total degradation period, defined as the time window from the 10 % threshold until 60 % were passed and the slope of the degradation curve was significantly lowered, took < 7 days.

Therefore, the substance has to be considered as readily biodegradable according to the OECD guideline 301 D.