Coupling electrooxidation-coagulation with membrane distillation using recycled Al can cathodes for sustainable...

Landfill leachate (LFL) is a complex wastewater with high concentrations of organic and inorganic pollutants, posing significant environmental challenges. While membrane distillation (MD) is an effective method for LFL treatment, membrane fouling remains a major issue, leading to reduced permeate flux and performance. This study introduces an integrated in-situ hybrid electrochemical pretreatment system, combining anodic electrooxidation (EO) and cathodic Al coagulation (EOC), where the generation of OH⁻ ions at the cathode drives the dissolution of aluminum, forming Al(OH)₃ coagulants that facilitate coagulation, to enhance LFL treatment in MD. Notably, the cathode is made from recycled beverage cans, contributing to the system's sustainability and cost-effectiveness. The EOC system demonstrates superior removal efficiencies compared to stand-alone EO and electrocoagulation (EC), achieving 72.9 % COD, 91.6 % DOC, 61.7 % UV₂₅₄, 44.4 % ammonia nitrogen, and 89.5 % hardness removal. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis showed that EOC preferentially degrades high-molecular-weight, aromatic, and unsaturated dissolved organic matter (DOM). When integrated with direct contact membrane distillation (DCMD), the EOC-MD system achieved 99.4 % organic removal efficiency and a 56 % improvement in permeate flux. Membrane surface characterization confirmed that EOC pretreatment effectively mitigated membrane surface fouling and preserved membrane hydrophobicity even after multiple MD cycles. In addition, energy consumption analysis revealed that the EOC-MD system achieved a 33 % reduction in energy consumption compared to the raw LFL-MD system. This integrated approach offers a promising, scalable, and eco-friendly solution for LFL treatment.