Pharmaceuticals at Penn State's living filter: From wastewater to groundwater

People use a large variety of chemicals in their everyday lives, including prescription drugs, over-the-counter medications, and personal care products. The chemicals in these products enter the wastewater stream and are not removed completely by wastewater treatment plants (WWTPs), causing these chemicals and their metabolites to persist in the treated effluent. The Pennsylvania State University has spray-irrigated all of its treated wastewater onto ∼240 ha of agricultural and forested land known as the "Living Filter" since the early 1980s. Once a week from October 2016 to March 2017, 24hr composite samples were collected after each treatment process through the WWTP. Water samples were collected monthly from 14 groundwater wells (20-100 m) at the Living Filter. Samples were analyzed for seven emerging contaminants: acetaminophen, ampicillin, caffeine, naproxen, ofloxacin, sulfamethoxazole, and trimethoprim. The goal was to track these compounds through the WWTP and ultimately to the wells at the Living Filter to assess: (i) the removal efficiency of the WWTP and (ii) the ability of the Living Filter's soil profile to provide further treatment of the compounds that persisted in the effluent. In general, the WWTP effectively removed acetaminophen and caffeine (>90%), and exhibited seasonal variability in the removal efficiency of the other compounds, with activated sludge as the most effective step for reducing contaminant concentrations. Concentrations in the groundwater were typically at least one order of magnitude lower than the concentrations in the WWTP effluent, suggesting that the soil generally acted as an effective biogeochemical filter, except during snowmelt events.