This study aims to investigate the effects of sludge components and agitation rate on contaminant removal, membrane filtration, and fouling in a membrane bioreactor (MBR) by using a dead-end stirrer cell. The real mixed liquor used for this study was pretreated to segregate three sludge components, namely activated sludge (AS), suspended solids (SS), and supernatant (SUP) including colloids and solutes. In reducing the contaminants, MBR filtration of AS and SS at agitation rates of 0 - 1000 rpm achieved higher efficiencies (20-30%) than those of achieved SUP filtration. In particular, the removal efficiencies of COD and T-P by the MBR were about three times higher than that of T-N. In reducing total organic carbon (TOC) and dissolved organic carbon (DOC), the MBR filtration of AS and SS achieved 1.7 times higher efficiency than that of SUP, whereas the MBR filtration of SUP in reducing ultraviolet at 254nm (UV₂₅₄) achieved 1.4 and 4.7 times higher efficiencies, respectively than those of AS and SS. On the other hand, the profiles of TMP build-up within 30 min of filtration time were larger, corresponding to AS > SS > SUP. This reveals that the solid level in developing TMP has a greater effects than dissolved level in mixed liquor. This result also indicates that both membrane filtration to lower TMP and an appropriate agitation rate (< 400rpm) are required to minimize membrane fouling by creating a shear force near the membrane surface, in order to prevent both micro-flocs generation and cake layer formation.