Effect of Climate on the Mobility of the Human Drug Carbamazepine.

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. Demand for reclaimed water for irrigation is highest when evaporative demand is high resulting in most recharge occurring from November through February. Sorption of the human drug carbamazepine was used as a model compound to determine the leaching potential of pharmaceuticals during recharge. The Freundlich distribution coefficient (K_f) was measured at different temperatures corresponding to typical native soil temperatures. K_f ranged from 0.4 at 40 C to 9.3 at 10 C. Based on these finding it is hypothesized that recharge using treated wastewater when soils are cooler has a lower likelihood of groundwater contamination with pharmaceuticals