Soil persistence and fate of carbamazepine, lincomycin, caffeine, and ibuprofen from wastewater reuse

The reuse of treated wastewater for groundwater recharge is an eff ective way to provide advanced treatment and water storage. Contaminants such as human drugs have been identifi ed as a potential problem for use of this water. Gilbert, Arizona maintains a 28.3-ha facility designed to recharge 15,150 m³ d^-1 through recharge basins constructed on native soil. Th e facility averages an infi ltration rate of >5 cm d^-1, resulting in the potential of pharmaceutical compounds leaching to groundwater. One 4-ha basin was selected for spatial sampling of four pharmaceutically active compounds (PhACs). Th e compounds were carbamazepine, lincomycin, ibuprofen, and caff eine. Soils were extracted and analyzed using pressurized liquid extraction and liquid chromatography-mass spectrometry-mass spectrometry. Th e concentration of ibuprofen was below detection limits in all samples. Lincomycin exhibited no net accumulation from year to year but had signifi cantly higher concentrations from depths of 0 to 5 cm than from depths >10 cm. Carbamazepine had the lowest concentration at 0 to 5 cm (0.18 ng g soil^-1), providing evidence that there is potential degradation of carbamazepine in surface soils. Carbamazepine also exhibited signifi cant accumulation from year to year. Caff eine exhibited net accumulation and had higher concentrations in surface samples. Th e accumulation of PhACs in the soil beneath recharge basins indicates that PhACs are being removed from the infi ltrating water and that, regarding ibuprofen and lincomycin, the treatment is sustainable due to the lack of accumulation. Regarding carbamazepine and caff eine, further investigations are needed to determine possible management and environmental conditions that could prevent accumulation.