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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

The test substance underwent essentially complete primary biodegradation by day 2 of the study.

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A Porous Pot Test according OPPTS method 835.3220 and GLP has been conducted (Springborn Smithers Laboratories 2006). The purpose of this study was to determine the biodegradation of the non-radiolabeled test substance in activated sludge contained in a porous pot bioreactor under conditions simulating an actual wastewater treatment plant. The test substance (i.e., 5.00 mg a.i./L) was exposed to a concentration of microorganisms typical for conventional domestic activated sludge wastewater treatment plants and monitored for biodegradation via dissolved organic carbon (DOC) disappearance and chemical specific analysis. At each sampling interval, the concentration of the test substance in solution and adsorbed to activated sludge was determined by high performance liquid chromatography with ultraviolet detection (HPLC/UV) to evaluate potential biodegradation and adsorption of the test substance.

The results of the study indicate that the test substance, when added to the sewage influent at 5 mg/L (3.71 mg C/L), underwent essentially complete primary biodegradation by day 2 of the study. DOC effluent levels from the test substance unit were consistently 2 to 3 mg/L higher than the control unit receiving sodium benzoate. This observation suggests that the test substance was transformed to several water-soluble organic compounds that were possibly detected by the HPLC/UV analytical method at retention times ranging from 5.1 to 5.7 minutes.