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Description of key information

In anaerobic, static sediment/water microcosms, TAME does not biodegrade.
In WWTP with adapted sludge, such as industrial installations, TAME can be characterised as "readily biodegradable".

Key value for chemical safety assessment

Additional information

In an anaerobic, static sediment/water microcosm study TAME was not degraded in 180 days (6 months) under all conditions tested; sulfate and/or nitrate reducing conditions and/or methanogenic conditions (Mormile et al. 1994). Sediments were collected from sites chronically contaminated with petroleum hydrocarbons. Inoculum was indigenous sedimentary micro-organisms occurring under anoxic/anaerobic subsurface conditions.

After 182 days of incubation TAME did not biodegrade under the test conditions in anaerobic sediment/water test system (Suflita and Mormile, 1993). Samples were collected from sites of contaminated chronically with municipal landfill leachate.

The anaerobic biotransformation of TAME in sediments was evaluated under different anoxic electron-accepting conditions over 3 years by Somsamak et. al. (2001). Enrichments were established with a polluted estuarine sediment inoculum under conditions promoting denitrification, sulfate reduction, Fe(III) reduction, or methanogenesis. Complete primary degradation of TAME was observed under sulfate-reducing conditions, concomitant with the reduction of sulfate. The primary degradation product of TAME was tert-amyl alcohol (TAA) indicating that O-demethylation was the initial step in TAME biodegradation under sulfate-reducing conditions. Further degradation of TAA did not occur. No transformation of TAME was observed under the other electron-accepting conditions over 3 years (Somsamak et al. 2001).

In a study to simulate a waste water treatment plant containing adapted micro-organisms, TAME was 94 -99% degraded provided the hydraulic retention time was at least 15 hours and the inlet concentration less than ~80mg/L. In the same study, it was clearly demonstrated that the rate determining step in degradation is the parent compound; breakdown products are metabolised more quickly than the parent compound.