Device comprising a compartment for separating the solids and liquids, said compartment comprising a base (7) that is concavely curved according to a cylindrical portion having a transverse axis and is formed of a sieve (143)； an idler roller (1) mounted transversely on an arm (13)； driving means which actuate said arm (13), and resilient means for adjusting the pressure exerted by the rollers (1)； wherein both the contact interface between the sieve (143) and the roller (1) and the rotational interface between the roller (1) and the arm (13) are made of a non-metal material on at least one of the two contacting surfaces that form each of said interfaces, such that, at said interfaces, there is no metal-on-metal contact between surfaces moving relative to one another.
