Apparatus for separating immiscible liquid mixtures, such as oil-water mixtures, includes a closed loop tubular enclosure having a liquid mixture inlet and independent liquid outlets spaced from each other and from the inlet. The inner cross section area of the enclosure has a first reduced portion adjacent the first outlet and a second further reduced portion adjacent the second outlet. Selectively absorbent elements are driven around within the enclosure, preferably by the pressurized liquid mixture, for selectively absorbing the liquid mixture and selectively discharging one of the liquids through the first outlet upon mild compression by the first reduced portion and the other of the liquids through the second outlet upon higher compression by the second further reduced portion. A third outlet with a still further reduced portion may be provided for discharging the remaining portion of the other liquid. The final reduced portion also provides a differential piston hydraulic driving force for the selectively absorbent elements and also prevents backflow from the inlet directly to the last outlet.