An electrodialysis operation have been performed to remove nitrate from a ground water containing 800 ppm of total dissolved solids (TDS) and 90 ppm of nitrate. The influence of electrodialysis parameters of nitrate removal was studied in order to determine the optimum conditions to prevent the possible precipitation of bivalent salt and to minimize the use of acid and antiscalant in the concentrate compartment. The optimal conditions to remove nitrate with a blockade of the bivalent anions especially sulfate in the dilute compartment have been proposed. (C) 2002 Elsevier Science B.V. All rights reserved.