Fate of Nonyl Ethoxylate Surfactants in Wastewater Treatment Plants

An assessment was made of the ability of wastewater treatment plants to remove nonylphenol ethoxylate (NPE) surfactants that are used widely in domestic and industrial applications. This was in preparation for the publication of US EPA Water Quality Criteria for nonylphenol, a biodegradation intermediate of nonylphenol ethoxylates. The key findings of this work are summarized in this paper and compared to more recent published data. This paper also provides guidance on the factors that influence the removal of NPEs in wastewater treatment plants. As with the degradation of many anthropogenic compounds, it is important to operate biological treatment systems at high solids retention times (SRT) with minimum levels of approximately 10 days. This observation has been confirmed by the results from more recent investigations.