Behavior of Endocrine Disrupting Nonylphenol in Sewage Treatment Plant

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The purpose of this study is to investigate the behavior of alkylphenol (AF) suspected of endocrine disrupting effects at a combined sewage treatment plant (STP) and at Tama river receiving effluents from several STPs in both dry and wet weather.In the influent of the STP, 4-t-butylphenol (BP) was detected in the range of 0.1-0.2 μg/L, 4-t-octylphenol (OP) of 0.2-0.4 μg/L and nonylphenol (NP) of 2.8-7.5 μg/L in dry weather. Most of OP and NP were adsorbed on the suspended solids (SS). Side stream from the sludge treatment process contained 0.8-1.7 μg/L of OP and 18.6-44.2 μg/L of NP. The effluent contained no BP, 0.0-0.1 μg/L of OP and 0.7-1.4 μg/L of NP resulting in removal rates of 100% in BP, 75% in OP and 85 % in NP toward the sum of the influent and the side stream. On the other hand, the concentration of NP in wet weather was 3.1 times higher in the influent and 1.6 times higher in the effluent than those in dry weather.Waste activated sludge (WAS) contained 0.07-0.26 μg/g DS of OP and 0.86-3.57 μg/g DS of NP and the mixed sludge (MS) of WAS and primary sludge (PS) did 0.02-0.06 μg/g DS of OP and 0.39-1.86 μg/g DS of NP. The WAS was 2-3 times higher than the MS in concentration of OP and NP.In Tama river, NP was detected in the range of 0.0-0.2 μg/L at Fuchu-Yotsuya bridge in dry weather. When it was rainy on the previous day, however, the concentration of NP was three times higher at maximum than that in dry weather.It was revealed that the level of NP at the combined STP seemed to be higher in both influent and effluent by precipitation, and that the level of NP at Tama river was also affected by precipitation.