Verbleib ausgewählter Xenoestrogene in der Kläranlage

The xenoestrogenic substances 4-nonylphenoxy acetic acid, 4-nonylphenol, bisphenol A and benzyl-n-butyl phthalate are present in effluents of wastewater treatment plants. In order to obtain information about the behaviour of these pollutants in the wastewater treatment plant activated sludge was incubated with these compounds under batch conditions. The xenoestrogens had already been sorbed by the fresh activated sludge from wastewater. Depending on the incubation time (4 h and 7 d, respectively) 2 to 4 μg/l 4-nonylphenoxy acetic acid and 4 to 6 μg/l benzyl-n-butylphthalate but only traces of bisphenol A (0.1 μg/l) had been desorbed in pure mineral medium from the activated sludge (protein content 3 mg/l). In mineral medium with additions of 4-nonylphenoxy acetic acid, bisphenol A, and benzyl-n-butyl phthalate the concentration of benzyl-n-butylphthalate increased immediately after the addition of the activated sludge from 8 μg/l to 110 μg/l and then was resorbed to 11 μg/l within 4 h. No biological elimination of benzyl-n-butyl phthalate could be measured after an incubation time of 7 d at 30°C.4-Nonylphenol was also strongly sorbed.Within 1.5 h 23% of the added 295 μg/l 4-nonylphenol had been adsorbed to the glass surface of the culture vessel and 84% by the activated sludge. Bisphenol A and 4- nonylphenoxy acetic acid on the other hand had not been sorbed significantly. However, within 7 d nearly all of the bisphenol A (5 μg/l,residual 0.2 μg/l) and 24 μg/l of the 4-nonylphenoxy acetic acid (38 μg/l, residual 14 μg/l) were biotransformed by activated sludge (3 mg/l protein). At the same time the concentration of 4-nonylphenol increased by 4 μg/l in the culture medium, presumably as a biotransformation product of 4-nonylphenoxy acetic acid. No further biotransformation of 4-nonylphenol was observed.