Process optimization of dairy wastewater treatment by electrocoagulation using response surface methodology

In this study, response surface methodology (RSM) approach using Central Composite Design (CCD) was applied to develop mathematical model and optimize process parameters for COD, color, orthophosphate, TSS and turbidity removal from dairy wastewater by electrocoagulation process using iron and aluminium electrodes. Evaluation of the effects and interactions of process variables; pH, current density and reaction time were studied. 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 efficiencies using Statgraphics Centurion XVI.I software programme. Under optimal values of process parameters 98.91 % COD and 98.24 % orthophosphate removal efficiencies with Fe electrodes, 98.84 % COD and 99.78 % orthophosphate removal efficiencies with Al electrodes were obtained. The operational cost including both electricity and the electrode consumption at optimum conditions were determined to be 0.54 and 0.42 €/m3 for Fe and Al electrodes, respectively. The sludge formed under optimized conditions in EC process was characterized by FT-IR analysis. Results of the study show that RSM is a powerful tool for optimizing the operational conditions of electrocoagulation for COD, color, orthophosphate, TSS and turbidity removals from dairy wastewater.