Fate of Estrogenic Compounds During Municipal Sludge Stabilization and Dewatering

This project convened a team of experts in the fields of environmental engineering (AECOM), analytical chemistry and hydrogeology (USGS), and biological assay analysis (UA) to evaluate the occurrence and fate of estrogenic compound, and the estrogenicity of biosolids derived from wastewater treatment. Sludge and biosolids samples were collected through the solids treatment train of four wastewater treatment plants (WWTPs) operating a range of solids processing, treatment and disposal options that are typical to facilities across the United States. Targeted solids processing methods included thickening via gravity, gravity belt, and dissolved air flotation; stabilization via lime addition, aerobic digestion and anaerobic digestion; chemical conditioning; dewatering via centrifuge; and other processes including composting and pelletization. Targeted disposal options included beneficial reuse or disposal including land application, dedicated land disposal and landfilling. Samples were collected from the study plants between two and five times over two years, allowing for an assessment of seasonal variation. In some cases, sampling density was not sufficient to assess seasonal variations, but for certain compounds interesting seasonal trends were observed. The solids samples were supplemented by liquid samples at key locations in the study plants during several sample collection events.