The effect of biomass characteristics on the partitioning and sorption hysteresis of 17α17α-ethinylestradiol

A membrane bioreactor (MBR) and a conventional bioreactor (CBR) were operated under various conditions to manipulate the biomass characteristics and evaluate the ensuing effects on the partitioning and sorption hysteresis of 17α17α-ethinylestradiol (EE2). When the biomass was grown without nitrogen limitation, the biomass mean particle size had a dramatic effect on the observed partitioning coefficient (Kd)Kd) and on sorption hysteresis index (HI). MBR KdKd (0.33–0.57 L/g) values were equal to or larger than those of the CBR (0.25–0.33 L/g). Under nitrogen-deficient conditions, the correlations between the biomass particle size and KdKd and HI were poor, likely because of extracellular polymeric substances. The KdKd and HI were determined for initial EE2 concentrations between 100 and 1000μg/L. Changing the SRT did not manipulate particle size, and the effects on KdKd and HI were not dramatic. This study also numerically explored the impacts of sorption hysteresis on the removal of pharmaceutical compounds.