Contribution of effluents from hospitals and private households to the total loads of diclofenac and carbamazepine in municipal sewage effluents-modeling versus measurements

The anti-epileptic drug carbamazepine and the non-steroidal anti-inflammatory drug diclofenac are frequently found as residues in the aquatic environment and also in samples of ground and drinking water. For both compounds, their loads occurring in the effluents from a military hospital and in the combined (household and hospital) sewage of a sewage pumping station (SPS) and a large municipal sewage treatment plant (STP) were predicted and measured within a field trial by collecting and analyzing defined composite samples over a time period of 1 week. The use of pharmacokinetic data and precise information on the administration of the individual medicinal formulation was found to be essential for the validity of the predicted data. The measured data confirmed the validity of the predicted loads with recoveries between 63 and 102% for carbamazepine and around 35% for diclofenac in the hospital wastewater. A comparison of the weekly loads predicted and measured in the influents and effluents of a STP in Berlin (Germany) yielded a very low removal rate for diclofenac (less than 15%) and a removal rate of up to 40% for carbamazepine. In total, 2.0 kg of carbamazepine per week (105 kg/a) and 4.4 kg of diclofenac per week (226 kg/a) were discharged into Berlin's surface water by the municipal STP, which treats both household sewage from approximately one million inhabitants and large amounts of hospital effluents (approximately 12,060 hospital beds).