Laboratory-scale batch and soil columns experiments were conducted to investigate the attenuation of estrogens (17β-estradiol and 17α-ethinylestradiol) during managed aquifer recharge. The role of microbial activity in the removal of selected estrogens was evaluated by comparing the results from biotic and abiotic batch experiments. Moreover, batch experiments were carried out using the sand media prepared over different acclimation periods to investigate the impact of acclimation periods on the removal of selected estrogens. Batch studies showed that adsorption was the dominant removal mechanism in the removal of 17β-estradiol and 17α-ethinylestradiol. 17β-estradiol and 17α-ethinylestradiol were attenuated by 99% and 96%, respectively, in batch experiments under oxic conditions. Redox conditions did not show any significant effect on the attenuation of 17β-estradiol. However, the net estrogenicity of 17β-estradiol remaining was lower under oxic conditions (130 ng estradiol-equivalents/L) than anoxic conditions (970 ng estradiol-equivalents/L). Column studies operated at 17 h of empty bed contact time also demonstrated that removal mechanism of 17α-ethinylestradiol was more dependent on adsorption than biodegradation.

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