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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
Study period:
2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
Chlorinated tetradecanes with levels of chlorination of 41.3, 45.5, 50.0, 55.0 and 60.2%.

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Secondary activated sludge (02-07-2010) was obtained from the wastewater treatment plant Nieuwgraaf in Duiven, The Netherlands. This plant is an activated sludge plant treating predominantly domestic wastewater. The activated sludge was preconditioned to reduce the endogenous respiration rates. To this end, 400 mg dry weight (DW)/L of activated sludge was aerated for one week. The sludge was diluted in the BOD bottles (van Ginkel and Stroo, 1992).
Duration of test (contact time):
56 d
Initial test substance concentration
Initial conc.:
2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
The Closed Bottle tests were performed according to Test Guidelines (OECD 1992). The nutrient medium of the Closed Bottle test contained per liter of deionized water: 8.5 mg KH2PO4, 21.75 mg K2HPO4, 33.4 mg Na2HPO4·2H2O, 22.5 mg MgSO4·7H2O, 27.5 mg CaCl2, 0.25 mg FeCl3·6H2O. Ammonium chloride was omitted from the medium to prevent nitrification. The test substances were added to the bottles using stock emulsions of 1.0 g/L prepared with the help of polyalkoxylate alkylphenol. The tests were performed in 0.3 L BOD (biological oxygen demand) bottles with glass stoppers. Use was made of 3 bottles containing only inoculum, and series of 3 bottles containing the respective test substances, polyalkoxylate alkylphenol and inoculum. Controls with polyalkoxylate alkylphenol but without test substance were included. The concentration of the test substances and polyalkoxylate alkylphenol in the bottles was 2.0 mg/L. The activated sludge was diluted to 2 mg DW/L in the mineral salts medium and the river water spiked with nutrient medium salts was used undiluted. Each of the prepared solutions was dispensed into the respective group of BOD bottles so that all bottles were completely filled without air bubbles. Each of the prepared solutions was dispensed into the respective group of BOD bottles so that all bottles were completely filled without air bubbles. The bottles were closed and incubated in the dark. The biodegradation was measured by following the course of the oxygen decrease in the bottles with a special funnel. This funnel fitted exactly in the BOD bottle. Subsequently, the oxygen electrode was inserted in the BOD bottle to measure the oxygen concentration. The medium dissipated by the electrode was collected in the funnel. After withdrawal of the oxygen electrode the medium collected flo wed back into the BOD bottle, followed by removal of the funnel and closing of the BOD bottle (van Ginkel and Stroo 1992).
Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
>= 13 - <= 66
Sampling time:
28 d
Remarks on result:
other: range of results, difference vary based on chlorination
Parameter:
% degradation (O2 consumption)
Value:
>= 19 - <= 71
Sampling time:
42 d
Remarks on result:
other: results vary depending on level of chlorination
Parameter:
% degradation (O2 consumption)
Value:
>= 21 - <= 74
Sampling time:
56 d
Remarks on result:
other: results vary depending of level of chlorination
Details on results:
See full results in attached report.

Applicant's summary and conclusion

Conclusions:
Biodegradability is retarded by increasing degree of chlorination, though biodegradation continued for even the highest chlorinated test material in an extended study.
Executive summary:

Biodegradability is retarded by increasing degree of chlorination, though biodegradation continued for even the highest chlorinated test material in an extended study.