Use of aerated magnetic biofilm reactor to treat wastewater

A novel aerated magnetic biofilm reactor is introduced in this study. The biofilm has a high biomass concentration and can be formed instantaneously. A 1 L laboratory-scale bioreactor packed with 160 flat ring magnets as biofilm carriers was used. Each piece of magnet has 1.6cm outer diameter, 0.7cm inner diameter, and 0.3cm thickness. Magnetic field intensity at the surface of the magnet was 700 gauss. The bioreactor was seeded with flocculated activated sludge supplemented with Fe3O4 powder. Calculated organic loading rate per unit volume of the reactor and unit area of the packing material was 1.5g COD/L d and 17.44g COD/m(2 )d, respectively. The effluent TSS was relatively very low and can be easily separated from water by a small gravity clarifier. The efficiency of nitrogen removal was much better for the thick magnetic biofilm reactor than of a control suspended growth bioreactor. Simultaneous nitrification and denitrification during aerobic phase was observed. These features make this technology an attractive and promising one to be used for intensive nitrogen removal along with organic load removal.