Process optimization of tannery wastewater treatment by electrocoagulation and electro-fenton techniques using response surface methodology

In this study, response surface methodology (RSM) approach using Central Composite Design (CCD) is applied to develop mathematical model and optimize process parameters for COD and TSS removal from tannery wastewater by electrocoagulation and electro-Fenton processes using iron electrodes. ANOVA was used to analyse the data and to obtain the interaction between the process variables and the responses. Analysis of variance (ANOVA) showed the relative significance of process parameters in removal process. The second-order regression model was developed to predict the removal efficiency using Statgraphics Centurion XVI.I software programme. The optimal conditions were found to be reaction time 5.0 min, pH 3.31, current density 53.72 mA/cm2, and H2O2 dose 0.14 M for electro- Fenton and reaction time 40.4 min, pH 7.0 and current density 50.9 mA/cm2 for electrocoagulation for COD removal whereas reaction time 45.0 min, pH 2.0, current density 65.0 mA/cm2, and H2O2 dose 0.06 M for electro- Fenton and reaction time 45.0 min, pH 5.48 and current density 65.0 mA/cm2 for electrocoagulation for TSS removal. At optimum conditions 54.8% and 87.3% COD removal efficiencies was achieved in electrocoagulation and electro-Fenton processes, respectively. At optimum conditions 86% and 88% TSS removal efficiencies was achieved in electrocoagulation and electro-Fenton processes, respectively.The operating costs for elecrocoagulation and electro-Fenton processes at optimized conditions were calculated to be 0.64 €/m3 and 0.68 €/m3. Electro-Fenton pocess is found to be more effective in tannery wastewater treatment.