Statistical optimization of chemical oxygen demand removal from wastewater by electrochemical oxidation

The independent and combined effects of four variables (current density, electrolyte concentration, air flow rate and pH) on COD removal from wastewater by electrochemical oxidation were optimized using 2(4) full factorial experimental design. ANOVA was conducted to test the combined effects of the independent variables (the four control factors and time) on COD removal. To determine the reaction order of COD removal, 1st, 2nd or 3rd reaction orders were considered; 1st order kinetics showed the highest average r(2) value. The backward elimination regression method was used to determine the 1st order k(COD) equation, and main effects and 2-way interaction effects on the 1st order equation were investigated. Using this equation, k(COD) values for the 16 experimental conditions were predicted and COD values were calculated with respect to time. Finally, we tried to determine optimal operating conditions using color and COD removal as endpoints using the multiple response surface method.