Electrochemical degradation of distillery spent wash using catalytic anode: Factorial design of experiments

In the present study, electrochemical degradation experiments were conducted to degrade distillery spent wash. It was performed with ruthenium oxide coated titanium mesh acting as anode and stainless steel as cathode. The effects of current density, dilution, electrolysis time and pH on the degradation rate were investigated. Increasing the initial pH and dilution decreases the decolorization efficiency. At the same time, increasing the chloride concentration and increasing the current density increased the color removal. The combined effects of these factors were optimized using factorial design of experiments for color removal and chemical oxygen demand (COD) removal. Regression models were developed to study the interaction among the variables for both the color removal and COD reduction. The optimal removal of color of 83.31% and COD degradation of 39.66% was obtained for current density (14.285 mA/cm2), electrolysis time of 3 h and at dilution of 10% distillery spent wash at slightly acidic pH 5.5. The actual color removal and COD degradation at optimal conditions are 81% and 37%, respectively, which confirms close to factorial design results.