Abstract: An apparatus for separating at least one selected medium from a liquid influent stream includes an assembly for dividing the influent stream into a plurality of smaller streams at an interface and means for filtering the smaller streams as they each flow along a discrete flow path substantially distinct from the flow paths of the other smaller streams. The apparatus is particularly suited for removing oils, greases, and suspended solids from a water oil mixture and is of a compact overall shape to permit mobile on-site use of the separator, for example, to remove contaminants from an aqueous mixture drawn out from a contaminated water table. The assembly for dividing the influent stream into smaller streams may include a diffuser plate having a plurality of apertures and the filtering assembly may include a head of oil disposed adjacent the diffuser plate for acting on the smaller streams created by the flow of the influent through the apertures of the diffuser plate.