Influence of manganese and ammonium oxidation on the removal of 17α-ethinylestradiol (EE2)

Flow-through reactors with manganese oxides were examined for their capacity to remove 17α-ethinylestradiol (EE2) at μg L−1 and ng L−1 range from synthetic wastewater treatment plant (WWTP) effluent. The mineral MnO2 reactors removed 93% at a volumetric loading rate (BV) of 5 μg EE2 L−1 d−1 and from a BV of 40 μg EE2 L−1 d−1 on, these reactors showed 75% EE2 removal. With the biologically produced manganese oxides, only 57% EE2 was removed at 40 μg EE2 L−1 d−1. EE2 removal in the ng L−1 range was 84%. The ammonium present in the influent (10 mg N L−1) was nitrified and ammonia-oxidizing bacteria (AOB) were found to be of prime importance for the degradation of EE2. Remarkably, EE2 removal by AOB continued for a period of 4 months after depleting NH4+ in the influent. EE2 removal by manganese-oxidizing bacteria was inhibited by NH4+. These results indicate that the metabolic properties of nitrifiers can be employed to polish water containing EE2 based estrogenic activity.