Multistep Optimization and Residue Disposal Study for Electrochemical Treatment of Textile Wastewater Using Aluminum Electrode

This paper reports multistep optimization studies on electrochemical (EC) treatment of textile wastewater containing three dyes namely basic orange 30, basic violet 16 and basic green 4 using an aluminum electrode. Chemical oxygen demand (COD) and color removal efficiencies were maximized in a batch EC experimental reactor. In first step, Plackett-Burman (PB) design was used to sort most effective factors amongst the various factors namely current density (j), time (t), electrode gap (g), temperature (T), initial pH (pH(o)) and NaCl salt concentration (m) that affected the removal efficiency. In the next step, steepest accent/descent method and Box-Behnken (BB) design methods were utilized to evaluate the optimum electrochemical conditions. In BB design, three operational parameters, namely j: 117.64-196.07 A/m(2); t: 150-210 min and pH(o): 3.5-5.5 were taken as input parameter whereas COD removal (Y-1) and color removal (Y-2) were taken as responses of the system. At the optimum operating conditions of j - 185.30 A/m(2), t = 190 min and pH(o) 5, more than 70.5% COD and 98.2% color removal efficiencies were observed. Field emission scanning electron microscopy of aluminum electrodes, scum and sludge has been carried out to understand the EC mechanism.