Modeling and Multi-Objective Optimization of Electrocoagulation Operating Parameters for Urban Wastewater Treatment

Abstract

In this study, the electrocoagulation (EC) process that uses electric current to remove contaminants from water, was used to optimize the treatment of urban wastewater. This process is an alternative treatment method that has attracted increasing attention, which are often limited by high costs and significant sludge production. The study aimed to optimize the turbidity (cloudiness caused by suspended particles) and chemical oxygen demand (COD, which measures organic pollutant levels) using response surface methodology combined with a central composite design. The experiment was conducted using real effluent from a wastewater treatment plant. The initial COD was 386.70 mg/L and the turbidity was 202.29 NTU. Four key parameters were studied: current intensity (X1), electrode surface area (X2), electrolysis time (X3), and stirring speed (X4). This process relies on the dissolution of sacrificial iron anodes. This generates metal hydroxides that destabilize pollutants via charge neutralization and adsorption. Variance analysis showed an excellent fit of the mathematical models, with high coefficients of determination (R2 = 97.72 for turbidity and 99.25 for COD). The current intensity was the most influential factor for both responses. Turbidity removal followed a nearly linear behavior. However, COD removal exhibited significant quadratic effects (p = 0.004), suggesting a more complex response behavior that may involve mechanisms, such as adsorption and oxidation, although these mechanisms were not directly investigated in the present study. Multi-objective optimization enabled the identification of ideal operating conditions: a current intensity of 0.6 A, an electrode surface area of 300 cm2, a time of 60 min, and agitation at 300 rpm. Under these conditions, the study achieved experimental removal efficiencies of 96.85% for turbidity and 92.10% for COD, showing high agreement with predicted model values. This study confirms that RSM-optimized electrocoagulation constitutes a highly effective solution for the purification of domestic effluents, paving the way for more sustainable industrial applications. The efficacy of electrocoagulation as an environmentally sustainable method for minimizing wastewater contamination. Multi-objectives simultaneously optimize wastewater pollution treatment's effectiveness, expressed by the yield of turbidity and demand chemical in oxygen (COD). Quadratic models accurately predicted removal efficiencies with high R2. Current intensity was identified as the most influential factor for all responses. The process achieves near-total turbidity removal (~100%) and a remarkable 97.57% reduction in COD. The CCD- based optimization provides a robust framework for wastewater treatment .