A separator and method for separating a heterogeneous supply into a liquid and a solid material. The separator includes a casing in which the supply can collect, and which has an inlet for receiving the supply and an outlet for conveying the supply. The separator also includes a screen which rotates relative to the casing. The screen has perforated sections having a plurality of perforations which permit passage of the liquid. The screen allows for the accumulation of the supply within it, which rises to a level corresponding to a supply height. As this supply height, a screening pressure acts against the perforated sections so as to compact the solid material against the perforations while the liquid passes therethrough. A suction unit sucks the compacted solid material from the perforations, and is disposed higher than the supply height. A supply level regulator regulates the level of the supply within the screen.