Taguchi Modeling for Techno-Economical Evaluation of Cr+6 Removal by Electrocoagulation Process With the Aid of Two Coagulants

The research aimed to apply the Taguchi method for techno-economical evaluation of Cr+6 removal using the electro-coagulation process with the aid of two different coagulants (FeCl3 and PAC). Taguchi orthogonal array L27 (313) was applied for analyzing the effect of four variables including initial pH, reaction time, current density and coagulant types in an attempt to improve the chromium removal efficiency. Based on the signal-to-noise ratio (S/N) and the analysis of variance (ANOVA), the results indicated that the reaction time was the most important variable on the hexavalent chromium removal efficiency. However, the current density, reaction time and coagulant types significantly influenced the operating costs. The optimum conditions for the mentioned variables were found to be an initial pH of 7, a reaction time of 60 min, a current density of 12.5 mA/cm2 and FeCl3 as a coagulant. Due to the interaction between the initial pH and coagulant type at pH 7, PAC also considered as a coagulant in this experiment. Under the mentioned conditions, the removal efficiencies of 92% and 95% were achieved using the chromium removal process by FeCl3 and PAC, respectively.