Fate of polybrominated diphenyl ethers, nonylphenol, and estrogenic activity during managed infiltration of wastewater effluent

About a billion cubic meters of wastewater effluent are artificially recharged annually in the United States for maintenance of groundwater levels and prevention of seawater intrusion. There is concern that trace contaminants, including various endocrine disrupting compounds (EDCs), are not completely removed during infiltration, leading to deterioration of groundwater quality. In this work, we investigate the mechanisms and efficiency of EDC removal at the Sweetwater Recharge Facility, which is used to recharge secondary effluent from the Roger Road Wastewater Treatment Plant in Tucson, Ariz. Material was collected from the top meter of sediments in two infiltration basins and analyzed for extractable nonylphenol (NP), polybrominated diphenyl ethers (PBDE) and total estrogenic activity. The basins differed significantly in length of service (7 versus 15 years). Nevertheless, profiles of extractable contaminants and estrogenic activity were similar in the two basins. Results suggest that hydrophobic determinants of estrogenic activity are efficiently retained in surface sediments during soil-aquifer treatment. However, measurable levels of PBDEs, NP, and estrogenic activity are present in infiltrate that reaches the local unconfined aquifer at ∼40 m below land surface.