Pollution of the Aquatic Environment with Steroid Estrogens
Henrik Rasmus Andersen
Pollution of the aquatic environment with steroid estrogens and xeno-estrogens
from sewage outlets causes development of imposex and stimulates non physiological
synthesis of vitellogenin in feral fish.
The first topic for this Ph.D. thesis was to investigate if concentrations
of these estrogenic substances in sewage outlets were higher than the
published effect concentrations in Denmark and therefore if it could be
expected that feral fish are affected. It was concluded that estrogen
concentrations are higher than published effect concentrations in a minority
of the investigated cases which means that effects can occur. Based on
comparisons of concentrations in sewage effluents and effect concentrations
for each estrogenic chemical suspected of causing environmental effects
it is concluded that the active ingredient in the contraceptive pill,
17a-ethinylestradiol, poses the highest risk of causing estrogenic effects.
The natural steroid estrogens, 17ß-estradiol and estrone are also
significant contributors to the estrogen load.
In order to improve the knowledge about the environmental chemistry of
steroid estrogens and hence the possibility to improve the removal of
steroid estrogens, the fate of steroid estrogens was investigated in a
sewage treatment plant with a remarkably good removal rate for steroid
Analytical methods for quantifying steroid estrogens concentrations in
sewage and sludge were developed. With these methods concentration profiles
were created for steroid estrogens through the treatment process of the
sewage treatment plant.
A mass balance for the steroid estrogens concluded that all three steroid
estrogens were primarily degraded by biodegradation in the active sludge
treatment step of the plant. Sorption to sludge removed 4 % or less of
the steroid estrogens from the plant. Sorption and desorption were, however,
important for the dynamic of the steroid estrogen fate inside the treatment
process, which is illustrated by the steroid estrogens being mainly sorbed
to sludge during some stages of the treatment process.
Comparison of the total mass balance of the sewage treatment plant with
a less detailed mass balance performed on the plant before major reconstruction
leads to the conclusion that the important factors for a excellent removal
of steroid estrogens were a high sludge retention time and a long retention
time for water in the active sludge treatment.