Central composite modeling for electrochemical degradation of paint manufacturing plant wastewater: One-step/two-response optimization

Abstract

Paint manufacturing wastewaters contain highly toxic and organic biorefractory substances and have adverse effects on human health. In this study, the removal of color and chemical oxygen demand (COD) from a paint manufacturing plant (PMW) wastewater by electrochemical degradation using Ti/Pt anodes were investigated with a five-factor central composite model. pH (4–11), temperature (10–40°C), NaCl concentration (10–100 mM), current (5–15 A) and feed rate (10–40 mL/min.) were selected as independent operating parameters. The results obtained were analyzed with analysis of variance and a quadratic model was developed to examine the effects of parameters affecting degradation conditions. Optimum conditions for maximizing color and COD removal while minimizing energy consumption were determined by numerical optimization and found to be pH of 4, temperature of 39.99 °C, NaCl concentration of 100 mM, feed rate of 40 mL/min and current of 5.21 A. Under optimum conditions, the estimated color removal was 79.68% and the COD removal was 80.54%. The compatibility of the predicted optimum conditions was confirmed by experimental data. In experiments performed under optimum conditions, the energy consumed by the system was calculated as 8.51 kWh/m 3 and the operating cost to treat 1 m 3 PMW was determined as $1.02. • Numerical optimization was applied using central composite modeling to treat PMW. • The established model was found suitable for estimating the responses. • The linear effect of all parameters significantly influenced the responses. • NaCl greatly reduced energy consumption and enhanced the degradation of pollutants. • COD and color were met Turkish water pollution discharge standards.