Abstract

The present study had as purpose the investigation of the impact of four highly used pharmaceutical active compounds (PhACs) on the nitrification, a crucial process in wastewater treatment plants (WWTPs). Nitrosomonas europaea is known to be sensitive to toxic compounds and was used to examine the effects of four different PhACs (trimethoprim, ibuprofen, acetaminophen and 17-α-ethinylestradiol) on microbial activity, specifically by measuring nitrite production. Significant inhibition was measured for some PhACs at 10 µM concentration when compared to controls that did not contain PhACs. The highest inhibitory PhAC was determined to be trimethoprim (19±2%) followed by ibuprofen (17±7%) and the least inhibitory compound was 17-α-ethinylestradiol (7±0.2%). No effect was observed in the presence of acetaminophen even at 100 µM. Additional experiments were performed to determine whether the inhibition was reversible. The results suggest that inhibition for trimethoprim, ibuprofen and 17-α-ethinylestradiol was reversible upon removal of these PhACs. The data suggest that PhACs may affect important microorganisms found in wastewater treatment.

Key words: Environmental contaminants, pharmaceutical active compounds (PhACs), Nitrosomonas europaea, nitrification, wastewater treatment processes, inhibition.