The influence of selected pharmaceuticals on biogas production from laboratory and real anaerobic sludge.

The presented study summarizes laboratory tests results to define the inhibition effect of selected pharmaceuticals on biogas production under anaerobic digestion conditions. Two sets of inhibition tests were realized: (i) with real anaerobic sludge (from municipal wastewater treatment plant (WWTP) where sludge is present and includes a wide spectrum of pharmaceuticals over a long period) and (ii) with laboratory sludge (sludge without pharmaceuticals). Methanogenic tests lasting 20 days were performed with three analgesics (diclofenac, ibuprofen, and tramadol), two antibiotics (amoxicillin and ciprofloxacin), ß-blocker (atenolol), three psychoactive compounds (carbamazepine, caffeine, and cotinine), and a mixture of these compounds. All tests were performed with two concentrations of pharmaceuticals (10 µg/L and 500 µg/L). Results of the methanogenic tests showed the different behaviors of the investigated sludges in the presence of individual pharmaceuticals. Stimulation of anaerobic digestion was mostly detected for laboratory (unadapted) sludge (e.g., the addition of ibuprofen at a concentration of 500 µg/L increased biogas production by 61%). On the other hand, pharmaceuticals inhibited biogas production for real sludge (e.g., the addition of ciprofloxacin 500 µg/L decreased biogas production by 52%).

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

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).