Understanding of the fate of oestrogen and oestrogenic compounds is important in improving the removal efficiency for oestrogens in wastewater treatment plants (WWTPs). In this study an attempt was made to clarify the fate of oestrogen, oestrogen sulphates, and oestrogenic compounds (synthetic oestrogen, nonylphenol and its relatives) by an instrumental analysis, and the fate of oestrogenicity by an in vitro assay. The investigation was conducted in an activated sludge WWTP in winter and summer, focusing on identification of the primary substances that induce oestrogenicity. Wastewater samples were analysed by employing the silica-gel fractionation technique in conjunction with two-step column chromatography. The results revealed that, in winter, the WWTP efficiencies for the removal of nitrogen and oestrogens decreased and the oestrone level increased with the progress of the treatment. Oestrone and oestrogenic substances are likely to circulate between the aeration tank and the final sedimentation tank. In summer, however, these compounds were effectively removed in the WWTP. The results of the column chromatography coupled with the bioassay suggested that E1 and E2 are the predominant contributors to the oestrogenicity in the influent, return sludge and effluent of the WWTP. The measurement by the instrumental analysis supported these findings.

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