In palm oil extraction process, a large amount of lipids are emulsified in waste stream and the hot, brownish palm oil mill effluent (POME) is generated. In this study, the membrane technology was proposed to test the feasibility of direct ultrafiltration (UF) of POME by using a-Al2O3 and PVDF membranes, and to figure out the recovery rates of water and oi. POME synthesis methodology was successfully generated in the lab with the oil droplet size distribution and oil concentration conforming to the characteristics of real POME. The optimal operating conditions for POME filtration was determined by executing ultrafiltration experiments at different permeate fluxes and pHs. Both membrane shown good performance at original POME pH (pH 5). Compared with PVDF membrane, Al2O3 shown great strengths in higher optimal flux (57LMH), lower required trans-membrane pressure (TMP), higher oil and water recovery. The formation of oil layer on Al2O3 membrane reversed the charge type of membrane surface, which transformed oil droplet-membrane attraction to oil droplet-oil layer repulsion that allowed for the higher rejection and steady filtration process. The effect of SDS surfactant was also studied to clarify whether it could significantly improve membrane performance. The addition of SDS brought in extra pollutant with the SDS micelle size smaller than membrane pores, which reduced permeate quality and increased fouling in UF process. In the aspect of process stability, SDS benefited a-Al2O3 membrane performance more than PVDF membrane. The bi-layers SDS formed on a-Al2O3 membrane resulted in charge inversion and increased hydrophilicity of membrane surface that respectively enhanced anti-fouling property and membrane permeability. In the long run, SDS addition stabilized TMP variation process and prevented the sharp TMP increase. However, to guarantee the permeate quality of membrane technology, SDS was not recommended to be added. To operate POME process with more stable TMP and less fouling, a-Al2O3 membrane was highly recommended for POME treatment with great potential of industrial application in the future. The discussion of pH effect on membrane performance reveals other important affecting factors other than pH. Severe fouling of PVDF membrane happened below IEP_PVDF (pH 2). The increased hydrophobicity caused by oil layer formation could explain the lower membrane permeability and the adsorption of more hydrolyzed LCFA in acidic condition led to larger proportion of irreversible fouling. While the less excellent a-Al2O3 membrane performance at pH 10 was mainly due to the adsorption of more LCFA and glycerol onto membrane, despite the membrane-molecules/oil droplets repulsion existed in ultrafiltration. Although the general filtration mechanisms involves in almost all cases, the most important interactions that mainly function vary with different membrane and feed type.