PHARMACEUTICALS IN ALLUVIAL GROUNDWATER: DETECTION AND REMOVAL

Since the first reports of pharmaceuticals in groundwater (circa 1996 Berlin), there has been thousands of articles written on these compounds in environmental waters. Groundwater has received much less attention than river waters because of the direct influence of sewage and its disposal to surface waters. Furthermore, there is considerable interest these days in water reuse, especially in the arid western United States where water is at a premium. One such example is the Prairie Waters Project in Aurora, Colorado, USA (Denver). The South Platte River, which originates in the mountains west of Denver, has much of its water removed before arriving into Denver, where as much as 85% of its flow may be derived from the Denver Metro sewage plant, which gives 130 x 10⁶ gallons per day (200 cfs to the South Platte River). One of the purification methods to apply to wastewater is bank filtration, where river water is pumped through sand deposits to alluvial groundwater wells. This is an area of concern for pharmaceuticals in groundwater, in our estimation. We have completed a one-year sampling program of the South Platte River and two alluvial wells used for bank filtration. A set of 20 compounds which included medications for high blood pressure, seizures, allergies, antidepressants, antibiotics, antibacterials, and anti-tussives, reveal that there is considerable transport of these compounds in alluvial groundwater. Removal rates varied from no removal to nearly 97% removal. Both biological degradation and sorption are involved. In at least one case there was an increase in concentration due to the degradation of pharmaceutical metabolites back to parent compounds. This presentation will discuss the major compounds being found and their removal processes from groundwater. Finally, the future issues of pharmaceuticals in alluvial groundwater and water reuse will be discussed in detail.