Biotransformation of Pharmaceuticals and Personal Care Products (PPCPs) during Nitrification: The Role of Ammonia Oxidizing Bacteria versus Heterotrophic Bacteria

Preliminary experiments to investigate the fate of 17α-ethinylestradiol (EE2) during nitrification were conducted. Sorption experiments were performed by incubating inactivated ammonia oxidizing bacteria and various heterotrophic cultures in the presence of ¹⁴C-EE2 at 10 μg/L. Biotransformation experiments utilized LC-MS and LC-ITMS analysis of supernatant collected during batch cultivation of monoculture of Nitrosomonas europaea with EE2. Results confirmed that sorption of EE2 onto heterotrophic biomass is an important mechanism that must be considered when describing the fate of EE2. During batch incubation with N. europaea, 98% of EE2 was transformed, producing a unique metabolite corresponding to a mass/charge ratio of — 386 m/z. Short term inhibition study results also suggest that inhibition of respiration in N. europaea as measured through nitrite generation rates is not significant at concentrations at or below 1 mg EE2/L.