Simultaneous removal of phenol and nitrate in an anoxic fluidized bed reactor

Abstract

The general purpose of this study was to characterize a biological treatment system for phenol removal in an anoxic fluidized bed reactor (AFBR) that employed nitrate as the final electron acceptor. The average influent phenol concentrations in the study were 52, 107, 201, 335, and 518 mg/L so that phenol was not detected in the effluent for influent concentrations up to 335 mg/L. The removal efficiency dropped to 70% when the AFBR was operated with influent phenol concentrations above 500 mg/L. The ratio of carbon (derived solely from phenol) to nitrate (N-NO₃) was approximately 1. Hence, the average influent N-NO₃ concentrations in the study were 45, 79, 157, 260, and 362 mg/L, with corresponding nitrogen removal efficiencies of 94%, 89%, 86%, 79%, and 51%. Nitrite accumulation was not observed because the average effluent N-NO₃ concentration during the entire reactor operation period was 1.5 mg/L.

Keywords:

• Anoxic process
• phenol
• nitrate
• denitrification
• C/N ratio
• anoxic fluidized bed reactor

Acknowledgments

The authors gratefully acknowledge the financial support of CNPq, CAPES and FAPESP.