In this study, a self-designed simultaneous crossflow electrocoagulation/electrofiltration (EC/EF) treatment module was evaluated for its overall treatment performance by treating chemical mechanical polishing (CMP) wastewaters including Cu-CMP wastewater and oxide-CMP wastewater. The critical electric field strengths for Cu-CMP and oxide-CMP wastewaters were, determined to be 35 and 30 V/cm, respectively. Crossflow EC/EF performance tests were carried out based on the 2(3-1) fractional factorial design using the electric field strength, crossflow velocity, and transmembrane pressure as the operating parameters. Experimental results have shown that the permeate turbidities were all below 0.5 NTU for Cu-CMP and oxide-CMP wastewater treated under the optimal operating conditions. Besides, the removal efficiencies of total solids content, total organic carbon, and silicon for Cu-CMP wastewater were 88%, 64%, and 79%, respectively; whereas 86%, 71%, and 82%, respectively for oxide-CMP wastewater. In this study, the unit Sludge yields resulted from the EC/EF process for both Cu-CMP and oxide-CMP wastewaters were found to be less than that of the traditional chemical coagulation process. (c) 2006 Elsevier B.V. All rights reserved.