Removal of 17α-ethinylestradiol and total phosphorus in a sequencing batch reactor under two different sludge retention-time conditions

Remoção de 17α-etinilestradiol e fósforo total por um reator em batelada sequencial sobre dois diferentes tempos de retenção de sólidos

Abstract

Sewage treatment systems can prevent the direct discharge of endocrine disruptors, such as 17α-ethinylestradiol (EE2), into the environment. Treatment systems capable of promoting total phosphorus (TP) removal, such as sequencing batch reactors (SBRs), are promising in this regard. Two lab-scale SBRs with different sludge retention times (SRTs) were assessed for their EE2 and TP removal rates. Anaerobic/aerobic/anoxic phases with cycles of 6 h were used to treat sewage containing EE2 at a concentration of 5 μg L^-1. The removal rates of chemical oxygen demand and TP were approximately 80% for both the SBRs. Partial nitrification was observed in the SBRs. Initially, concentrations of EE2 above 1.0 μg L^-1 in the treated sewage were measured. These concentrations were smaller in SBR 1, which used lower SRTs; EE2 was removed by sludge sorption. After the 56^th cycle, the concentrations of EE2 in the treated sewage were below 0.1 μg L^-1 in both the SBRs, indicating that its removal may have occurred by biodegradation due to acclimation to the process. Therefore, both TP removal and nitrification seem to play an important role in EE2 removal by SBRs.

Keywords:
A2O SBR; EE2 and TP removal; sewage treatments