Occurrence and Degradation of Estrogenic Nonylphenol and its Precursors in Northeast Kansas Wastewater Treatment Plants

Abstract

Estrogenic nonylphenol polyethoxylates (NPnEOs) constitute an important class of nonionic surfactants that find wide use in industrial and domestic cleaning products. These chemicals can undergo partial biotransformation to yield the estrogen mimicking nonylphenol (NP). Our investigations at three Northeast Kansas wastewater treatment plants (WWTPs) found NPnEOs and NP in influent wastewater at levels from nondetectable to more than 200 μg/L. Conventional unit processes at these WWTPs were not completely effective in removal of these organic wastewater contaminants. Low levels (up to 23 μg/L) of NPnEOs and NP were detected in the WWTP effluents that are discharged into the Kansas River. A large portion of NPnEOs and NP appeared to adsorb to the biosolids, a phenomenon that likely prevented their degradation in the bioreactors. As much as 898 mg/kg NP was measured in biosolids from one WWTP. Onsite composting appeared to reduce NP, nonylphenol mono-ethoxylate (NP1EO), and nonylphenol di-ethoxylates (NP2EOs) in the biosolids.