Removal of natural and xeno-estrogens during conventional wastewater treatment

The ecological impacts of natural estrogens and xenoestrogens in treated wastewater include altered sexual development and sex ratios among continuously exposed organisms. The primary sources of estrogenic activity in wastewater are natural estrogens such as estrone, 17β-estradiol and estriol and synthetic compounds like 17α-ethinylestradiol, alkylphenols and alklphenol ethoxylates. Precursors in raw wastewater can yield estrogenic intermediates during wastewater treatment. All these compounds can be destroyed by biochemical processes, albeit at significantly different rates or under different conditions. That is, estrogenic compounds can be, but are not always, destroyed by conventional wastewater treatment processes, suggesting that conventional processes can be optimized for removal of estrogenic activity from wastewater. Sorption to sludges derived from wastewater treatment affects the fates of hydrophobic xenoestrogens such as nonylphenol, in part because the biodegradability of sorbed contaminants is limited. It may also be possible to tailor sludge stabilization processes to remove trace contaminants, including estrogens. For example, there are significant differences in the efficiencies of aerobic and anaerobic digestion for destruction of alkylphenols and probably other estrogenic compounds with aromatic moieties. Because advanced wastewater treatment is not economically feasible for most communities, there is ample incentive to develop accurate relationships between operational parameters and removal of estrogenic compounds during secondary wastewater treatment.