Fate of Selected Estrogens in two Laboratory Scale Sequencing Batch Reactors Fed with Different Organic Carbon Sources

Estrogens are potent endocrine disrupting compounds commonly found in municipal wastewater effluent, although their removals from various wastewater treatment plants vary considerably. This study compared the ability of two laboratory-scale sequencing batch reactors, each of which performed organic carbon oxidation and nitrification but with different bacterial communities, to remove 17β-estradiol and 17α-ethinyl estradiol. The more diverse bacterial community had superior estrogen removal than the less diverse community, particularly for 17α-ethinyl estradiol. Under an SRT of 40 days, the 17β-estradiol mass was 30% of the amount under the solids retention time of 20 days, and the 17α-ethinyl estradiol mass was likewise 40%. In addition, the amount of estrogens sorbed onto the biomass dominated the concentration profile when compared with the amount in the liquid phase. These results suggest that differences in the bacterial ecology and SRT could be reasons for variations among wastewater treatment plants to remove estrogens.