Occurrence and Elimination of Nonylphenol Ethoxylates and Metabolites in Municipal Wastewater and Effluents

Abstract

Abstract A survey of the concentrations of nonylphenol ethoxylates (NPnEO) and their metabolites in wastewater samples collected from a Canadian sewage treatment plant using primary and secondary treatment is presented. Twenty-four-hour composite raw sewage, primary effluent and final effluent samples were collected monthly over a one-year period. Levels of NPnEO (n = 1 to 17) and their metabolites, nonylphenol (NP) and nonylphenoxy carboxylic acids (NPnEC), in these samples were determined by HPLC and GC/MS methods. While ca. 85% of the total alkylphenolics in raw sewage are ethoxylates, the major component (nearly 80%) in the final effluent was in the form of carboxylic acids. During this study period, the median total alkylphenolic concentrations in raw sewage and final effluent were 526 and 248 nmol/L, respectively, representing an overall elimination rate of 53%. The estimated daily discharge of the nonylpheno-lics to the aquatic environment varied from 15 to 44 moles, with a median value of 20 moles. These data suggested that conventional sewage treatments are ineffective in the removal of the surfactant-derived metabolites.