| An examination of the sorption mechanisms of the two most common cholesterol-lowering drugs, atorvastatin and simvastatin to the primary clarifier biosolids found in a municipal wastewater treatment plant was conducted. Both of these drugs are highly prescribed and have a large fraction of the consumed drug excreted. Research findings show that only about 10% of these two drug compounds will sorb to the solids entering a wastewater treatment plant, with the remainder passing to the aerobic basins for biodegradation by activated sludge bacteria.;The rate and extent of biodegradation by wastewater treatment plant bacteria was also examined as part of this investigation using both a batch and a continuous-flow configuration. These experiments show an apparent cometabolic rate of biodegradation, indicating that the rate is primarily dependent on the amount of bacterial food sources present. Data also allow for an estimate on the percent removed by biodegradation based on the average time spent in an aerobic biodegradation basin at a wastewater treatment plant.;Along with fundamental investigations into the fate and transport of two statin drug compounds, this research included the development and application of a model to estimate prescription pharmaceutical loadings to and releases from wastewater treatment plants. A mass-balance, population-centric approach was taken, and national databases on drug prescription rates, average daily doses, and metabolic excretion rates were used to develop the model. The model was also coupled with two models developed by the U.S. EPA to estimate percent removal by wastewater treatment plants and the impact on aquatic organisms for the top 150 prescription drugs and the potential impacts on a range of wastewater treatment plants in Virginia.;The final component of this investigation involved obtaining sampling data throughout the past year at two wastewater treatment plants in the state of Virginia, one in Charlottesville and one in Blacksburg. Ten different drug compounds were tested, and found present in wastewater entering the treatment plants. A demographic analysis was also conducted by sampling at both plants in the middle of January, first when undergraduate students were on break, and again two weeks later, after all the students had returned. |
