Removal efficiencies of top-used pharmaceuticals at sewage treatment plants with various technologies

The presence of pharmaceuticals in wastewater and the environment has attracted growing public concern. Although studies have been performed to detect pharmaceuticals in wastewater effluents, little research has been conducted to assess the efficiency of pharmaceutical removal using different treatment technologies. To assess the removal efficiencies of pharmaceuticals in wastewater, samples from 22 municipal treatment plants in Nova Scotia and New Brunswick were analyzed for 12 commonly used pharmaceuticals and 2 primary metabolites. The medians of removal efficiencies for 9 technologies: aerated lagoon, extended aeration, facultative lagoon, membrane bioreactor, modified secondary, oxidation ditch, primary treatment, rotating biological contactor, and sequencing batch reactor technologies, were determined to be 98.0%, 96.4%, 98.2%, 99.8%, 68.4%, 99.0%, 3.0%, 81.3%, and 98.3%, respectively. The medians of removal efficiencies of individual pharmaceuticals were found from -14.4% to 100%. Primary treatment showed significant differences comparing to other treatment technologies. Very strong correlations of removal efficiencies were found between acetaminophen and warfarin, between cotinine and warfarin, between cotinine and paraxanthine, and between ramipril and atorvastatin. In general, there was no strong correlation of removal between pharmaceuticals and total organic waste load or total suspended solids.