Detection of selected pharmaceutical compounds and determination of their fate in modern lined landfills

Research was performed to characterize discarded household medication disposal in municipal solid waste (MSW) and the fate of selected pharmaceuticals in landfills. A community household pharmaceutical collection program was conducted to examine the quantity and characteristics of pharmaceutical compounds entering MSW and to determine factors affecting the efficiency of special programs for medication waste collection. Collection program data confirmed that the disposal methods for medications most commonly utilized by households were predominantly the sewage system and MSW. Information gathered from participants showed that program efficiency would be optimized by targeting older age groups, developing systems to reduce medication loss due to expiration, and providing a continuous, convenient collection point.;Three laboratory experiments were performed to determine the fate of pharmaceuticals in landfills. Six pharmaceutical compounds were examined: 17a-ethinylestradiol, acetaminophen, acetylsalicylic acid, ibuprofen, metoprolol tartrate, and progesterone. Adsorption to solid waste materials and other abiotic mechanisms played a strong role in retention of progesterone and 17alpha-ethinylestradiol in landfills and removal from landfill leachate. Adsorption and biodegradation were both factors in the fate of metoprolol tartrate and acetaminophen. Anaerobic biodegradation of acetylsalicylic acid was significant, while ibuprofen demonstrated a resistance to degradation and adsorption in all experiments.;Analysis of actual landfill leachate for the six pharmaceutical compounds from the laboratory experiments plus an additional four compounds (Caffeine, Cephalexin, Hydrochlorothiazide, and Prednisone) was conducted to characterize the discharge of pharmaceutical compounds from landfills. Ibuprofen was measured in 9 out of 10 landfill leachates and in the leachate of a solid waste transfer station and standing water on the face of a landfill. Other compounds detected included acetaminophen, acetylsalicylic acid (salicylic acid) and caffeine. Landfills which had the greatest number of compounds detected were those of the largest size, serving the largest population. Landfills which currently or previously practiced leachate recirculation, on average had higher concentrations of ibuprofen in their leachate than those which did not. Comparison of acetaminophen, acetylsalicylic acid, and ibuprofen inputs to wastewater treatment plants from landfill leachate treatment versus inputs from the sewage system showed landfills to be a significantly smaller source of active pharmaceutical ingredients.;The concentration of active pharmaceutical ingredients (APIs) in MSW was determined using a mathematical estimation and directly by performance of a waste composition study. In the mathematical estimation, the variable of greatest uncertainty was the quantity of medications which become unused once dispensed. An estimated range of APIs in MSW of 7.4 mg/kg to 45 mg/kg was calculated. In direct measurement, APIs comprised 8.1 mg/kg of MSW with 22 differing compounds present and another 33 identified as potentially present due to the presence of empty containers.