Hybrid Sono-Electrocoagulation Process for the Treatment of Landfill Leachate Wastewater: Optimization through a Central Composite Design Approach

Abstract

The effectiveness of the process of ultrasonication (US), electrocoagulation (EC) and hybrid sono-electrocoagulation (US+EC) on landfill leachate wastewater treatment was evaluated based on the removal efficiency of % color and % Chemical Oxygen Demand (COD) along with power consumption. The experimental results showed that the hybrid US+EC had a high color (100%) and COD (94%) removal efficiency with a lower power consumption of 4.50 kWh/m3 compared to the individual EC and US processes. In this hybrid US+EC process, the effects of various operating parameters were investigated and optimized using Design-Expert (12) based on the central composite design approach. The optimization results indicated a maximum COD removal efficiency of 71.05% with a minimum power consumption of 2.33 kWh/m3 at the following optimal experimental conditions: electrolyte concentration (X1) = 0.76 g/L, current density (X2) = 2.75 A/dm2, COD concentration (X3) = 3919.50 mg/L, sonication power (X4) = 100 W and treatment time (X5) = 36.05 min. The synergistic effect was calculated using the US, EC and US+EC process based on the % COD removal efficiency and has a positive effect of 20.51%. The % COD and % color removal efficiency were analyzed using a closed reflux method and UV-VIS spectrophotometer. Thus, the hybrid US+EC process, significantly enhances the efficiency of pollutants removal from landfill leachate wastewater.