The present work deals with the electromigration dispersion in microchannels by considering the Debye layer effect. For the present model we have considered a rectangular microchannel with a fixed surface charged density on the walls and fluid flows through the channel due to the influence of an external applied electric field. Due to local variation of the conductivity as well as the non validity of the local electroneutrality condition for non zero Debye layer thickness, the local eletric field is non constant and varies as a function of the solute concentration, wall surface charge density and ionic valencies. This electric field drives a fluid transport across the channel. The shear velocity then gives rise to a Taylor Aris dispersion. The non linear Taylor Aris dispersion coupled with the non linear electromigration of the ions gives rise to a non linear transport phenomena that is dependent on the Debye layer thickness. An expression is established that relates the evolution of ionic concentration with the variation of the local electric field. This equation helps elucidate the role of various parameters and how they affect solute dispersion.