The present embodiments provide methods and apparatuses for use in enhancing and/or treating fluids, such as fuels. Some embodiments provide apparatuses for use in treating fuel that comprise a first conduit having an input end, an output end, and a metallic interior surface; a second conduit positioned within and axially aligned with the first conduit, the second conduit having input and output ends, and a plurality of apertures distributed along a length of the second conduit; and an impeller assembly comprising an impeller positioned between an adaptor sleeve and shaft support where at least the impeller and shaft support are fixed within the second conduit, and the adaptor sleeve is positioned at the input end of the second conduit.