Statistical optimization of electrocoagulation for restaurant wastewater treatment using Box–Behnken design

Abstract

The discharge of untreated restaurant wastewater into the environment poses significant risks to receiving water bodies due to its high load of organic matter, fats, oils, grease (FOG), and detergent-based chemicals. In this study, electrocoagulation (EC) with aluminium electrodes in batch mode was investigated for the treatment of raw restaurant wastewater under varying operational conditions, namely applied voltage, initial pH, inter-electrode distance, and electrolysis time. A Box–Behnken response surface design (BBD) of RSM with four factors at five levels has been employed to optimize the process variables with the dual objective of maximizing COD removal while minimizing power consumption. ANOVA results and Pareto chart analysis highlighted the relative significance of each factor and their interactions, with voltage and electrolysis time emerging as the dominant contributors. The optimized conditions—15.1 V, pH 7.51, inter-electrode distance 0.83 cm, and 55.32 min—achieved a maximum COD removal of 84.8% and a minimum power consumption of 30.1 kWh/m³. Furthermore, a comparative evaluation with literature on different wastewater streams demonstrated the applicability and competitiveness of EC for restaurant wastewater treatment.