Process for purifying glycerin derived from biodiesel production

A process for purifying glycerin derived from biodiesel production is described, the process comprises acidifying the glycerin; neutralizing the acidified glycerin; feeding the glycerin into an electrodialysis unit comprising at least one cation exchange membrane and at least one anion exchange membrane separated between an anode and a cathode, such that they define at least one diluted compartment and at least one concentrated compartment located between the anode and the cathode, wherein the glycerin is fed into the diluted compartment and an NaCl solution is fed into the concentrated compartment; applying a potential difference so that the ions present in the glycerin migrate through the anion and cation exchange membranes from the diluted compartments to the concentrated compartments, where they are trapped, purifying the glycerin; and extracting the purified glycerin.