Exploring 17α-ethinylestradiol removal, mineralization, and bioincorporation in engineered bioreactors

This research investigated removal, mineralization, and bioincorporation of 17α-ethinylestradiol (EE2) in membrane bioreactors and conventional bioreactors. When the influent EE2 concentration was >50 μg/L, the membrane bioreactor (MBR) biomass removed more EE2 than conventional bioreactor (CBR) biomass in continuous tests, likely because the sorption partitioning coefficients are higher for MBR biomass. Microautoradiography was carried out to investigate the distribution of EE2 within the aggregates retrieved from the bioreactors, and the results revealed concentration gradients present within the floc. Experiments using radiolabeled 14C-EE2 experiments (done with 24.5 μg/L EE2) showed that EE2 removal rates and the amount of EE2 mineralized were similar in MBRs and CBRs. Direct measurements and bioenergetic estimates suggest that EE2-related carbon is probably incorporated into active biomass, despite the fact that EE2 was added at a concentration that was much lower than that of the primary growth substrates.