Recently, Nonylphenol (NP) as a raw material of non-ionic surfactant, has been classified as endocrine disruptors in Japan. In this study, NP and Nonylphenol Ethoxylates (NPEO_n) in water and sludge from an inflow setting tank, activated sludge process, and dischargat one sewage treatment plant were measured using GC/MS and LC/MS to investigate the conversion of NP metabolites in each sewage process and the emission of NP metabolites into a water environment. In this result, we have discovered that the reduction of NP was 96% from inflow to discharge in this sewage treatment plant. The reduction of NPEO_2-9 was 85%. And, NPEO_2-3 accounted for 80% of NPEO_2-9 in sewage treatment plant discharge. The emission of NP and NPEO_n into a water environment was low value. However, it is possible that NP and NPEO₁ are generated in a sewage treatment plant using an activated sludge process only from the increases of NP and NPEO₁ in activated sludge process.

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