Pilot scale study using an anaerobic-anoxic-aerobic activated sludge process for the treatment of nitrogen and phosphorus removal from municipal wastewater in Taiwan was carried out. The BOD, TN and TP removal efficiency of 97.8%, 67.4% and 77.4% were achieved, respectively. Furthermore, effluent TN and TP were decreased to the lever of 8.7 mg/L and 1.13 mg/L, respectively. This showed that the biological treatment process used in this study could remove not only organic matter, but also nitrogen and phosphorus from municipal wastewater. The studies evaluating the rate of nitrification, denitrification, phosphorus release and phosphorus uptake were also performed. During steady state, average results of K-N, K-DN, K-PR and K-PU were 0.736 mgNH(4)-N/gMLSS-hr, 0.524 mgNO(3)-N/gMLSS-hr, 0.174 mgPO(4)-P/gMLSS-hr and 0.243 L/gMLSS-hr, respectively.