Sewage which nitrogen and phosphorus are much contained relatively in comparison with others was treated by the anaerobic/anoxic/oxic process of pilot-scale. The sewage characteristics and treatability were studied and the results obtained at a given experimental condition can be summarized as follows. Pollutant concentrations of sewage were shown in the ranges of TBOD 180∼470㎎/L (average 281㎎/L), TCOD 72∼157㎎/L(average 94㎎/L), SS 119∼570㎎/L(average 274㎎/L), TN 19∼107㎎/L(average 51㎎/L) and TP 2.2∼14.6㎎/L(average 5.3㎎/L). Influent concentration of pollutants was highest at 7 AM. In steady state, average removal efficiencies by this process were shown to be 92.5% in TBOD, 83.7% in TCOD, 93.9% in SS, 55.7% in TN and 75.3% in TP, respectively. TBOD removal in anaerobic basin was about 75% of total removed TBOD. It was possible to operate in volumetric loading rate of 1.5kg TBOD/㎥·day. Removal efficienices in this loading rate were shown to be above 80% in TBOD and SS, above 50% in TN and above 60% in TP. Observed microbial yield was 0.21g MLSS/g TBOD. Therefore, generation of excess sludge was about 50∼60% smaller than ones of activated sludge process.