Treatment of stabilized landfill leachate using powdered activated carbon: adsorption behavior and chemical regeneration.

Stabilized landfill leachates from long-operating landfills are characterized by their complex composition and high concentrations of recalcitrant organic compounds, posing significant challenges to conventional wastewater treatment. This study highlights the potential of powdered activated carbon (PAC) as an effective treatment method to address these challenges and offers insights into both its adsorption behavior and chemical regeneration capabilities. A commercial PAC based on eucalyptus wood was characterized and applied to a raw stabilized leachate sample, resulting in a substantial reduction in the concentration of dissolved organic carbon (DOC), especially the recalcitrant fractions such as the humic and fulvic compounds. The PAC exhibited high organic compound affinity, with an adsorption capacity of 753 mg.g^-1 for true color, which was well described by the Langmuir isotherm model. It was possible to reduce the true color by more than 97% using 50 mg.L^-1 of PAC. Additionally, it was possible to effectively regenerate the PAC using a solution of phosphoric acid, enabling the complete recovery of its adsorption capacity for all the analyzed parameters. The chemical regeneration process offers a sustainable and cost-effective approach for the long-term utilization of PAC to treat stabilized leachate.