The comportment of selected Pharmaceuticals in sewage treatment plants

摘要

The effluent of sewage treatment plants have been shown to be a significant source of pharmaceutical residuals in surface water. In order to determine and optimise the efficiency of wastewater treatment plants and derive basic knowledge on the behaviour of Pharmaceuticals, different treatment steps of a municipal sewage treatment plant were investigated. This article deals with common pharmaceutical active compounds (PhAC) for different applications which are known to occur in the effluent of wastewater treatment plants. In particular, two antibiotics (Roxithromycin, Sulfamethoxazole), two analgesics/antiphlogistics (Diclofenac, Ibuprofen), the antiepileptic Carbamazepine, the contrast media lopromide, the tranquilizer Diazepam and the lipid regulator Bezafibrate were selected. The investigations have been performed on a low loaded full-scale activated sludge plant for nutrient-removal and phosphorus precipitation with a high sludge retention time (SRT) of more than 100 days. Since April 2001 grab samples of the influent and effluent were taken once every two months. Furthermore three sampling periods over 10 days were performed in October 2001 and in May and July 2002. Daily composite samples of influent and effluent were taken during these sampling periods. A typical distribution over the year was observed for the antibiotic Roxithromycin in the influent of the treatment plant. Certain substances which showed no or only part elimination in parallel performed lab scale experiments which were implemented with much lower SRT, seemed to be degraded in the full scale plant. These results confirm the assumption that the elimination of Pharmaceuticals from waste-water correlates with the sludge retention time.