The rectangular airlift bubble column where anaerobic and aerobic regions coexisted was used, and the treatment of wastewater including nitrogen was performed. The effects of equipment and operation conditions on the gas holdup, liquid-phase volumetric mass transfer coefficient and liquid circulation flow rate were investigated in two different-size columns. On the basis of oxygen balance, the distribution of dissolved oxygen concentration in the column was calculated by using the experimental equations of flow characteristics. The results of wastewater treatment proved that the nitrogen removal was controlled by the volume fraction of anaerobic region.