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

Abstract

This research investigated removal, mineralization, and bioincorporation of 17α-ethinylestradiol (EE 2) in membrane bioreactors and conventional bioreactors. When the influent EE 2 concentration was >50 μg/L, the membrane bioreactor (MBR) biomass removed more EE 2 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 EE 2 within the aggregates retrieved from the bioreactors, and the results revealed concentration gradients present within the floc. Experiments using radiolabeled 14C-EE 2 experiments (done with 24.5 μg/L EE 2) showed that EE 2 removal rates and the amount of EE 2 mineralized were similar in MBRs and CBRs. Direct measurements and bioenergetic estimates suggest that EE 2-related carbon is probably incorporated into active biomass, despite the fact that EE 2 was added at a concentration that was much lower than that of the primary growth substrates. © 2010.