Abstract
Concentrations of natural estrogens such as 17β-estradiol(E2)and estrone(E1)in the water collected from sewage treatment plant(STP)were determined by ELISA. The concentration of natural estrogen in treated water decreased gradually through the treatment processes, but the concentration in the effluent water of final sedimentation tank (after activated sludge treatment)was still high. The residual ratio of the concentration of estrogens in the water of final sedimentation tank to those in the water of primary sedimentation tank(100%)ranged 25.9 - 50 %(E1)and 65.8 - 90.9 %(E2).However, the levels of estrogens in the water after stone contact oxidization(treatment process using biofilm on the surface of sgravels)decreased markedly, and the residual ratio ranged 3.5 -5.1 %(E1)and 10.7 - 12.1 %(E2). Degradability of estrogens by the microorganism in biofilm on surface of gravels was investigated using gravels collected from stones contact oxidization of sewage treatment plant, and in Muko River, Hyogo Prefecture. E2 and E1 were degraded within 2 - 3 days, and ethynylestradiol(EE2)being synthetic estrogen was degraded after about 10 days by the gravels of STP, whereas E2 and E1 were degraded within 5 - 6 days and 8 -9 days, respectively, by the gravels collected from Muko River, and it took 10 days more for the degradation of EE2. The biodegradation capability of E1 by biofilm on the surface of gravels in STP was superior to those in Muko River.
