An apparatus and method for separating joined components, purifying liquid, promoting interaction between two or more components and improving combustion. The apparatus has a housing, a rotor inside of the housing, a plurality of protrusions extending from the rotor, a shaft coupled with the rotor and a prime mover for rotating the shaft. Fluid within the housing cavitates as the rotor rotates and the protrusions move through the fluid. Cavitation causes joined components within the fluid to separate, kills undesirable organisms within the fluid, promotes interaction of components within the fluid and improves combustion of a liquid fuel. The fluid and components may also be subjected to abrasion and centrifugal and impact forces for separating the components, purifying the fluid, promoting interaction of the components and improving combustion.