Abstract: An apparatus for enhancing phase contact and chemical reactions is provided. The apparatus comprises at least one high-turbulence mixing stage and at least one high-shear-stress and high-cavitation stage. The stages are adapted to cause an increase in relative sliding speeds of phases involved in a multiphase flow passing through the stages. The high-shear-stress and high-cavitation stage comprises a rotor having radial teeth housed in a cavitation chamber surrounded by a stator having radial teeth. The facing surfaces of the radial teeth have a parabolic profile in circumferential direction. For each tooth, the parabolic profile lies along a curve of a parabola of which a vertex is arranged at a rear edge of the tooth, with respect to a direction of rotation of the rotor, and along a radius extending from the rear edge to a center of the rotor. The focus of the parabola is also located on the radius.