The present invention relates to a device for separating an effluent comprising phases of different density and conductivity, the device comprising a pair of electrodes (12, 13), means (10) for introducing the effluent between said electrodes, means intended for separation (3) and discharge (4) of said separated phases. The separation means comprise at least one centrifugation element including a helical channel (19) in which the effluent is centrifuged after passing between the electrodes. An opening extends over the entire periphery of said centrifuged effluent so as to discharge part of the centrifuged effluent. The discharge means further comprise sealing means for limiting discharge of the less dense phase through said opening.