<p>Methods for treatment of sludge with microwave irradiation for improving its dewatering are provided. In one embodiment, the method includes exposing the sludge to microwave irradiation at a power density of between about 3 W/ml and about 17 W/ml. Turbidity, total solids content and overall dewaterability are improved when the microwave irradiation treatment is combined with another method for dewatering sludge, such as enzyme treatment, conditioning with a flocculating agent and mechanical dewatering.</p>