Design and test of a bench scale drinking water treatment plant for the evaluation of pharmaceutical fate

The detection of pharmaceuticals in many surface and groundwaters has raised concerns because they are bioactive and often slowly biodegradable and they create potential for inadvertent exposure to humans via drinking water. However, prior to human consumption, most waters are treated and little is known about the removal of such compounds in drinking water treatment plants. To date, only a handful of studies have attempted to determine the fate of pharmaceuticals in drinking water treatment. To examine such fate, a modular, bench-scale drinking water treatment plant using alum coagulation/flocculation, sedimentation, dual-media filtration, granular-activated carbon (GAC), and chlorine disinfection was constructed. Four test compounds were selected for initial tests. These compounds were selected to represent a wide variety of properties associated with pharmaceuticals and include caffeine, salicylic acid, trovafloxacin mesylate, and 17-β estradiol. Radiolabel compounds were used to facilitate detection and enable a complete mass balance analysis. Results showed sorption to floc and filter media and biodegradation as the most viable removal mechanisms. While sorption to floc, sand, and anthracite was responsible for only small removals (<25 percent for all compounds), GAC provided >80 percent removals for three of the compounds.