Removal of 17β-estradiol (E2) and 17α-ethynylestradiol (EE2) by a sequencing batch reactor following UV/H2O2 process

The presence of nutrients and endocrine-disrupting chemical (EDC) hormones in the aquatic environment can affect wildlife and humans. Sewage treatment using biological processes followed by advanced oxidation processes can be a promising system for EDC removal, however, these have been little investigated in detail in the literature. This study evaluated the removal of nutrients, 17 beta-estradiol (E2), and 17 alpha-ethynylestradiol (EE2) from sewage using an anaerobic/aerobic/anoxic sequential batch reactor (SBR). Furthermore, the treated sewage generated was subjected to post-treatment using a UV/H2O2 system. Hormones were added to the synthetic sewage only once, and it was submitted to treatment by SBR. The residues of E2 and EE2 were measured in the treated sewage generated by SBR for 13 consecutive cycles. The total removal rate of phosphorus and nitrogen by SBR was in average greater than 75% showing the simultaneous occurrence of nitrification, denitrification, and phosphorus biological removal. Seventeen percentage of the added E2 was detected in treated sewage, but 85% of EE2 was discharged into the same treated after 13 cycles of SBR. Although the literature has indicated the removal of EE2 by sorption and/or biodegradation in biological sewage treatment systems with nitrification, including full-scale ones, this study suggested that this removal has been apparent. The remaining residues of E2 and EE2 were completely degraded by the UV/H2O2 process. The removal of organic matter and nutrients by SBR facilitated the oxidative action of the UV/H2O2 system with lower consumption of peroxide. The integration of these two processes is very promising for EDC removal.