Degradation of bisphenol A and nonylphenol by nitrifying activated sludge

Nitrifier-enriched activated sludge was used in batch degradation of bisphenol A (BPA) and nonylphenol (NP) to verify if ammonium-oxidizing activity within nitrifiers is responsible for the biodegradation of those compounds. Decreases in both BPA and NP concentrations occurred simultaneously with ammonium (NH4+) oxidation into nitrate (NO3−) by nitrifying sludge. However, when ammonium was replaced by nitrite (NO2−) in the medium, an acclimation period was required prior onset of significant degradation of BPA and NP. In the presence of inhibitors such as allylthiourea or Hg2SO4, BPA and/or NP reduction decreased significantly, implying that removal of BPA and NP was mostly mediated by biological activity rather than by physicochemical adsorption onto sludge flocs.