Occurrence and removal of pharmaceutical and hormone contaminants in rural wastewater treatment lagoons

Rural communities in the United States usually use a series of aerated lagoons to treat domestic wastewater. Effluents from these systems are typically discharged to receiving watersheds, which leads to a potential transfer of pharmaceuticals and personal care products (PPCPs) and steroid hormones from sanitary sewage to the environment. The primary objectives of this study are to identify and quantify PPCPs and steroid hormones in rural sewage treatment lagoons, to investigate the removal efficiency of these emerging contaminants in the treatment processes, and to monitor their occurrence in the surrounding watershed. In this study, a method has been developed to analyze thirteen PPCPs and eight steroid hormones in various water samples. Among all of the PPCPs considered, ten chemicals were detected in sewage influents, lagoon waters of different treatment stages, or effluents at concentrations in the ng/L to low μg/L range. Three hormones were observed in the influents at total concentrations as high as 164. ng/L, but no hormone residues were detected in the effluents. This indicates that the aerated lagoons may effectively remove hormone contaminants. With the exception of carbamazepine, removal rates for the other detected PPCPs were relatively high in the range of 88 to 100% in September with average air temperature equal to 20°C. However, the removal efficiency of nine PPCPs in the rural wastewater treatment plant exhibited large temporal variability. The concentrations of PPCPs in the lagoon waters and effluents collected in November, with average air temperature equal to 4.4°C, were 1-2 orders of magnitude higher than those samples collected in September. Occurrence of these PPCP contaminants in the surrounding watershed was also monitored. The discharge of effluents significantly elevated the PPCP concentrations in the receiving creek and increased their occurrence in the adjacent river.