Soil Persistence and Fate of Carbamazepine, Limcomycin, Caffeine, and Ibuprofen From Wastewater.

The reuse of treated wastewater for groundwater recharge is an effective way to provide advanced treatment and water storage in the desert southwest. Contaminants such as human drugs, found in treated effluent, have been identified as a potential problem for use of this water.  The town of Gilbert, Arizona maintains a 28.3 ha facility designed to recharge 15,150 m³ day^-1 through recharge basins constructed on native soil previously used for agricultural production.  On an annual basis the facility maintains an infiltration rate of more than 5 cm day^-1 resulting in the potential for leaching of pharmaceutical compounds to groundwater.  One 4 ha basin was selected for spatial sampling to a depth of 1.5 m for four pharmaceutically active compounds.  The compounds chosen were the anti-epileptic drug carbamazepine, the anti-microbial lincomycin, the analgesic ibuprofen, and the stimulant caffeine.  Soils were extracted using pressurized liquid extraction followed by analysis using LC-MS-MS.  All four compounds were found in at least one sample at concentrations above detection limits.  Compound distribution was related to soil texture, organic carbon content, and water solubility of the compound.  Data obtained provides guidance for selecting sites for future groundwater recharge facilities as well as potential operating parameters to protect groundwater.