Intensification of Electrocoagulation in Compost-Derived Wastewater

Electrocoagulation (EC) is a sustainable strategy for wastewater treatment, but the role of hydrodynamics and impeller design remains underexplored. This study assessed the impacts of electrode type (Al, Fe), impeller type (SBT, PBT), treatment time, and the inclusion of zeolite (ECZ) on the efficacy of compost wastewater treatment. The results obtained were also compared with those obtained in the EC treatment of the same wastewater in a reactor equipped with a folding paddle impeller. Key performance indicators included a decrease in chemical oxygen demand (COD), residual turbidity, electrode mass loss, energy consumption, pH, temperature, and settling behaviour. Al electrodes achieved higher COD removal (80–92%) but consumed more energy, while Fe electrodes showed slightly higher electrode mass loss. Zeolite increased residual turbidity but improved the settling behaviour during longer treatments. Fe electrodes led to larger pH shifts, whereas Al electrodes caused higher temperature increases. Compared with the folding paddle impeller, SBT and PBT promoted more favourable pH evolution, slightly higher COD removal, and lower residual turbidity. These advantages could be attributed to enhanced turbulence, mass transfer, and solid–liquid interactions, which enhance coagulant formation and dispersion. L8 Taguchi optimisation identified the addition of zeolite as the main factor influencing COD reduction, while treatment time was key for minimising electrode consumption. The findings demonstrate that impeller selection, combined with process optimisation, contributes to the mechanical process intensification of EC, improving treatment efficiency, electrode durability, and cost-effectiveness.