Removal of bisphenol A (BPA) in a nitrifying system with immobilized biomass

• Bisphenol A (BPA) in the influent limited ammonium oxidation.
• The efficiency of BPA removal rose with increased BPA concentration in the influent.
• BPA was mainly removed by heterotrophic bacteria.
• Ammonia-oxidizing bacteria (AOB) made a limited contribution to BPA removal.
• BPA affected the quantity and diversity of AOB in the immobilized biomass.

The potential for bisphenol A (BPA) removal by mixed consortia of immobilized microorganisms with high nitrification activity was investigated with BPA concentrations in the influent from 2.5 to 10.0 mg/L. The presence of BPA limited ammonium oxidation; nitrification efficiency decreased from 91.2 ± 1.3% in the control series to 47.4 ± 9.4% when BPA concentration in wastewater was the highest. The efficiency of BPA removal rose from 87.1 ± 5.5% to 92.9 ± 2.9% with increased BPA concentration in the influent. Measurement of oxygen uptake rates by biomass exposed to BPA showed that BPA was mainly removed by heterotrophic bacteria. A strong negative correlation between the BPA removal efficiency and nitrification efficiency indicated the limited contribution of ammonia-oxidizing bacteria (AOB) to BPA biodegradation. Exposure of biomass to BPA changed the quantity and diversity of AOB in the biomass as shown by real-time PCR and denaturing gradient gel electrophoresis.