Background: Estrogens and their synthetic analogues are widely used as pharmaceuticals. Upon oral
administration these drugs are eventually excreted via urine. The persistence of these pharmaceuticals and inefficient
removal by water treatment lead to accumulation in surface water and effluents with negative effects for
aquatic life and human health.
Methods: In this study, the uptake of estradiol by a combined magnetic ion exchange resin - ultrafiltration process
(MIEX-UF) was investigated. This is a relatively common process used in drinking water treatment for the removal
of natural organic matter. However, uptake of micropollutants, such as steroidal pharmaceuticals, may
occur as a side effect of water treatment due to the high affinity for polymeric materials. To elucidate the mechanism
governing estradiol partitioning between water, resin and membrane, the influence of different parameters,
such as pH, humic acid concentration and membrane molecular-weight-cut-off (MWCO) was studied.
Results: Humic acid concentration and pH affected estradiol uptake most. At pH 11 the most significant increase
of estradiol uptake was observed for MIEX-UF process (30 ng/g corresponding to 80%) compared with individual
UF (17 ng/g corresponding to 12%). The presence of humic acid slightly reduced estradiol uptake at pH 11
(about 55%) due to competition for the ion exchange binding sites.
Conclusion: Results demonstrated that the uptake of estradiol, which is amongst the most potent EDCs detected
in surface water, in the MIEX-UF process can reach significant quantities (30 ng/g of resin) leading to uncontrolled
accumulation of this micropollutant during drinking water treatment. This study gives a novel contribution
in the understanding the mechanism of the unanticipated accumulation of pharmaceuticals, such as estradiol, in
the drinking water treatment process.