The examination of some pharmaceutical compounds removal in aerobic systems under different operating conditions

Various researches showed that active ingredients of many pharmaceutical chemicals receiving to biological wastewater treatment plant after used were not removed totally. Removal rates of these chemicals could exhibit various results depending on the operational conditions of the treatment plants. Aim of this work was to determine the effect of various sludge retention times (SRT) and hydraulic retention times (HRT) using lab-scale continuous-flow stirred tank activated sludge reactor for the removal of naproxen, diclofenac, paracetamol, ibuprofen and sulfamethaxazole. In order to find out for the removal rates, 3 different SRT (10,20,30 days) and 2 different HRT (12 and 24 hours) operating conditions were examined. Highest removal rates were obtained under 30 days SRT and 24 hours HRT operating condition except for diclofenac. It was found that removal rates are negligible for diclofenac for all operating conditions tested. Values of biological degradation constant (kbiol) were also calculated for each pharmaceutical. According to results obtained paracetamol has the highest (kbiol) value compare to others.Adsorption characteristics of pharmaceuticals by activated sludge were also examined. Data from equilibrium experiments were applied to Langmuir and Freundlich isotherm models and data fitted to Freundlich model. Additionally, data from equilibrium experiments were also used for the calculation adsorption coefficient (Kd) for each pharmaceutical and highest Kd value was obtained for paracetamol as 419 L/kg.