An activated sludge system with cross-flow membrane filtration has the great advantages of being able to remove bacteria and retain a high concentration of sludge biomass in the reactor because this system can avoid the problem of solid-liquid separation. In this paper, using the bench scale submerged membrane system, treatment properties and temeprature effects have been investigated. Consequently, a high BOD removal rate (about 98%) was achieved. Although NH4-N loading was high, a high NH4-N removal rate (about 95%) was also obtained above 13 degrees C. Because the nitrification rate became dow at such a low temperature, NH4-N and T-N removal decreased rapidly below 13 degrees C.