Pharmaceuticals and illicit drugs – A new threat to the application of sewage sludge in agriculture

Abstract

The occurrence of 93 pharmaceuticals, illicit drugs and their metabolites has been investigated in stabilized sewage sludge from five municipal wastewater treatment plants (WWTPs) in the Slovak Republic. The total population connected to the tested WWTPs was approximately 600,000 p.e. which represents >20% of the Slovak population connected to public sewer systems. The sludge production from the five tested plants was >8100tons in 2016, which is approximately 15% of the total Slovak sewage sludge production in 2016.The highest total concentration of all pharmaceuticals was found in WWTP Bratislava Devínska Nová Ves (DNV) and Senec - 11,800 and 11,300ng/g dry matter (DM), respectively. Among individual pharmaceuticals, the highest concentrations were recorded for fexofenadine (mean 2340ng/g DM, maximum 5600ng/g DM in Bratislava DNV) and telmisartan (mean 1170ng/g DM, with a maximum of 3370ng/g DM in Senec). A principal component analysis revealed differences between pharmaceutical patterns in aerobically and anaerobically stabilized sludge.The worst-case scenario based on no further degradation of pharmaceuticals between sludge production and field application was used to predict pharmaceutical mass loads in agriculture. For the result, we estimated an annual load to soil in the Slovak Republic of up to several hundred kilograms of pharmaceuticals and drugs, with the maximum for fexofenadine (120kg/year) and verapamil (29kg/year).