Evaluation of Leachate Treatment from Piedras Blancas Landfill (Córdoba, Argentina) by coagulation–flocculation Coupled with a Photo-Fenton Reaction

This study evaluated the treatment of municipal solid waste (MSW) leachate from the Piedras Blancas landfill in Córdoba, Argentina, through a combined coagulation–flocculation and photo-Fenton process. Due to the high organic load and toxicity of landfill leachates, conventional biological treatments often show limited efficiency. Therefore, advanced oxidation processes were investigated as an alternative to improve pollutant degradation and enhance subsequent treatment stages.

Initially, four coagulants (PAC, FeCl₃, Al₂(SO₄)₃, and AlCl₃) were tested using Jar Test experiments to determine the most effective option for color and total organic carbon (TOC) removal. Among them, AlCl₃ showed the best overall performance, achieving 84% TOC reduction and 68% color reduction, and was selected as the optimal pre-treatment coagulant.

The pretreated leachate was then subjected to a photo-Fenton reaction under UV–Vis irradiation for 180 minutes. Different concentrations of Fe³⁺ and H₂O₂, as well as distinct H₂O₂ reinjection frequencies, were evaluated. The best results were obtained with H₂O₂ reinjections every 30 minutes, achieving an overall TOC reduction of 93% relative to the raw leachate.

Kinetic analysis revealed two different stages during the oxidation process. During the first 90 minutes, both treatments exhibited similar behavior, suggesting that H₂O₂ concentration was not initially limiting. After this period, TOC degradation rates increased significantly, indicating a greater influence of H₂O₂ availability and a more effective generation of hydroxyl radicals. Overall, the combined treatment demonstrated high efficiency for reducing the organic load of landfill leachates.