Alkylphenol Polyethoxylate Metabolites in Canadian Sewage Treatment Plant Waste Streams

Abstract

Abstract Nonylphenol polyethoxylates and their refractory metabolites, including nonylphenol, are on the second Priority Substances List (PSL2) to determine if they are "toxic" as defined under the Canadian Environmental Protection Act. This study addresses the need for data on their occurrence in raw sewage, final effluents and sludge in Canada. Samples of raw sewage, final effluent and sludge were collected from 16 wastewater treatment plants across Canada in 1995 and 1996. These samples were analyzed for 4-nonylphenol (4-NP), nonylphenol ethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO) and 4-4-tert-octylphenol (4-t-OP). Measurable quantities of these chemicals were found in almost all raw sewage and sludge samples. In the raw sewage, concentrations ranged from <0.005 to 21 μg/L for 4-t-OP, from 0.69 to 155 μg/L for 4-NP, from 2.9 to 43 μg/L for NP1EO and from 0.26 to 24 μg/L for NP2EO. Sludge concentrations (based on dry weight) ranged from <0.010 to 20 μg/g, from 8.4 to 850 μg/g, from 3.9 to 437 μg/g and from 1.5 to 297 μg/g for 4-t-OP, 4-NP, NP1EO and NP2EO, respectively. Of the final effluent samples, 60% contained detectable amounts of 4-t-OP and concentrations ranged from <0.005 to 0.37 μg/L. Almost all of the final effluent samples had detectable levels of 4-NP, NP1EO and NP2EO. The 4-NP concentrations varied from <0.020 to 13 μg/L, NP1EO was found in the range of 0.072 to 26 μg/L and NP2EO was found in the range of 0.099 to 21 μg/L.