Autotrophic nitrification and denitrification characteristics of an upflow biological aerated filter

摘要

Wastewater nitrification was carried out using a laboratory-scale upflow biological aerated filter (BAF) packed with a polyurethane-based porous medium. The filtration medium has macropores which provide a greater area for the development of biofilms. The macro-pores have both aerobic and anaerobic zones, depending on the depth of oxygen penetration in the medium. Wastewater ammonium was oxidized at a maximum rate of 1.8 kg NH_4~+m~(-3)d~(-1) and showed more than 90% nitrification efficiency in the BAF. During the biological nitrification of wastewater, condiserable nitrogen loss was observed in the BAF under oxygen-limited conditions when organic carbons were not provided for denitrification. Most probably, the lost nitrogen was converted to gaseous nitrogen compounds including dinitrogen by autotrophic dentrification and anaerobic ammonium oxidation.