Centrifugal fan and sewage treatment system

The invention relates to the technical field of sewage treatment and provides a centrifugal fan and a sewage treatment system. The centrifugal fan comprises a volute type machine body and an impeller.The volute type machine body is provided with a water inlet, a water outlet and an exhausting opening. The impeller is arranged in the volute type machine body. A water stop assembly is arranged in the volute type machine body. The impeller is located in the water stop assembly which comprises multiple water stop plates. Multiple through holes are formed in each water stop plate. The multiple water stop plates are uniformly distributed in the peripheral direction of the impeller. According to the centrifugal fan, under the high-speed rotating effect of the impeller, by means of collision between blades of the impeller and the water stop plates of the water stop assembly, sewage is drained through the through holes of the water stop plates, the multiple water stop plates enable the gas-liquid separation effect to