PARENT SESSION

1H a/b/c - Pesticides, pharmaceuticals, perfluoroalkylated substances, antibiotics
Poster Hall
8:30 AM - Wednesday, 30 April 2003
Chair: de Voogt, P.¹, ¹
Co-chair: Purdy, R.², Pluecken, U.³, Koerdel, W.⁴, Tolls, J.⁵, Kümmerer, K.⁶, ^{2 3 4 5 6}

(WEP/38) Biodegradation and Elimination of antibiotics in ready and inherent tests.

Gartiser, Stefan¹, Urich, Elke¹, Kümmerer, Klaus², ¹ Hydrotox GmbH, Freiburg, Baden-Württemberg, Germany² Institute of Environmental Medicine and Hospital Epidemiology, University Hospital, Freiburg, Baden-Württemberg, Germany

ABSTRACT- The biodegradation and elimination of antibiotics in municipal wastewater treatment plants is of particular concern because sewage is the main exposure route for antibiotics applied in human medical supply. Within a research project supported by the German Environmental Agency (F+E 298 63 722) the inherent biodegradability of 10 antibiotics has been determined in a combined test design based on the Zahn-Wellens test (OECD 302 B) and the CO₂-evolution test (OECD 301 B). Both ultimate biodegradation and DOC-elimination were observed at high inoculum concentration (200 mg/l d.s. activated sludge). Additionally the ready biodegradability of several antibiotics has been determined in the manometric respiratory test according to OECD 301 F. Only Penicillin G proved to be ultimately biodegradable in both test categories reaching ThCO₂ degradation degrees of 78-87% and ThOD degradation degrees of 29-100% without fulfilling the 10-day criterion. Among the others only Amoxicillin showed certain ultimate biodegradation in few of the parallel flasks. The DOC-elimination of Tetracyclin-HCl showed a typical degradation curve starting with 18% and reaching the plateau phase at 80% only after 21 days. Nevertheless the CO₂-evolution measured in parallel didn't support the data, thus indicating that the time needed for reaching the adsorption equilibrium is underestimated. Several other antibiotics showed considerable DOC-elimination in the inherent test while only minor incidences of ultimate biodegradation have been observed. The combination of CO₂-evolution and DOC-elimination is a suitable instrument for assessing the behaviour of chemicals within one test.

Key words: biodegradation, antibiotics, elimination, Test methods