PARENT SESSION
1F Human and Veterinary drugs in the environment
9:00 AM to 7:00 PM, Monday, 07 May 2001

(M/EH046) Fate and effects of an antibiotic mixture in sewage treatment plants.

Wiethan, Jürgen ¹, Unger, Jörg¹, Henninger, Almut¹, Kümmerer, Klaus¹, ¹

ABSTRACT- After administration, antibiotic substances are excreted by the patients into waste water, because most substances are metabolised incompletely, often even only in low extent. Therefore, larger quantities of antibiotic substances enter municipal sewage treatment plants. If they are not eliminated there, they could reach surface water or even drinking water. Several investigations have been reported about representatives of different antibiotic substances in almost every aquatic system, but the detected concentrations were almost low. Only little is known about their fate and effects in the environment. In simple OECD tests some antibiotics were not readily biodegradable, but only single substances were investigated. In sewage treatment plants antibiotics may disturb the bacterial populations resulting in growing resistance and/or worse elimination of organic substances hereby affect the biological purification process. In laboratory scale sewage treatment plants some important antibiotics had shown little effects on bacterial populations, depending on the used concentrations. Synergetic, antagonistic or neutralization effects on bacterial populations caused by similar or different effect mechanisms or effect spectrums aren not available by the investigation of single substances. In order to consider those natural effects a mixture of important antibiotics was studied in laboratory scale sewage treatment plants regarding the elimination of the antibiotics, the influence to the biological purification process and the affection to bacterial populations. Therefore classical microbiological methods were used, in situ chemotaxonomy methods as well as chromatograpic analysis. First results showed little effects on polyamines. Unlike this, there was a big influence on threadlike bacteria. Further biomarkers like phospholipids and quinones are investigated at the moment.

Key words: sewage treatment, antibiotic resistance, chemotaxonomy, substance elimination