MECHANISMS FOR REMOVAL OF 17α-ETHINYLESTRADIOL IN BIOREACTORS

Laboratory scale bioreactors were used to investigate sorption and biodegradation of 17α-ethinylestradiol (EE2). EE2 is among many emerging micropollutants that may cause impairment of developing organisms in the environment. Results showed that the mixed culture taken from the membrane bioreactor (MBR) had a sorption partitioning coefficient that was more than twice that of biomass taken from sequencing batch reactors (SBRs). We also showed that the MBR biomass was more hydrophobic than the SBR biomass. The ammonium monooxygenase (AMO) enzyme was extracted from a nitrifying mixed culture and it removed EE2 in batch experiments. These findings suggest that nitrifying MBRs may provide environmental protection from steroids via two distinct mechanisms related to particle hydrophobicity and AMO.