In this study, the absorption of oxygen from air flowing through polypropylene hollow fiber membrane contactor was investigated using slaughterhouse wastewater, including about 90% (v/v) blood, as an absorbent. The effect of operating parameters on process performance was examined in two modes of absorbent flowing through both the lumen and shell of the membrane contactor. In addition, some experiments were carried out to examine the long term performance of the system. Removal efficiency and absorption flux were determined for investigation of the process performance. Results showed decrease in gas flow rate and increase in liquid flow rate resulted in higher removal efficiency, respectively. Moreover, absorption flux was increased by augmenting both gas and liquid flow rate. Furthermore, the removal efficiency of near 78% was obtained for mode of wastewater flowing through the lumen side. No considerable variations in removal efficiency were observable for long term operation.