A fluid separation apparatus for separating a fluid mixture including at least two fluids having different densities comprising a vessel having a vortex generation zone located within a fluid reservoir which includes a vortex generation wall which increases the rotational velocity of a fluid mixture flowing through the vortex generation zone and directs the fluid mixture from the fluid inlet toward the upper surface of the fluid reservoir. The vessel also includes a fluid inlet which extends into the vortex generation zone; a first fluid outlet through which the less dense fluid exits the vessel; and a second fluid outlet through which the denser fluid exits the vessel. The apparatus further comprises a gas bubble generator which introduces gas bubbles into at least a portion of the fluid mixture before the fluid mixture enters the vessel through the fluid inlet.