A study by Aleksandra Wdowczyk and colleagues, published in Water Resources and Industry, evaluates the use of vegetation-activated sludge processes (V-ASP) to improve landfill leachate treatment using biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More and zeolite substrates. These low-cost materials were tested under varying conditions, focusing on their ability to reduce pollutants effectively.

Key findings include exceptional ammonium nitrogen removal rates of 99-99.8% across all systems, regardless of the hydraulic retention time (HRT). Total nitrogen removal ranged from 13.1% to 74%, with the highest reductions observed in zeolite-filled, vegetated systems. Chemical oxygen demand (COD) reductions were moderate, averaging 30-50%, while reductions in heavy metals like zinc and nickel reached up to 72.2%. Biochar and zeolite showed distinct pollutant adsorptionBiochar has a remarkable ability to attract and hold onto pollutants, like heavy metals and organic chemicals. This makes it a valuable tool for cleaning up contaminated soil and water.   More properties, with zeolite outperforming biochar for most parameters.

The study also highlighted the role of plants in enhancing treatment efficiency, particularly in removing organic nitrogen. Changes in substrate surface properties due to pollutant adsorption were confirmed using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM).

While the V-ASP systems tested were laboratory-scale, these findings support their potential for scalable landfill leachate treatment. Further optimization is needed to address remaining challenges, such as limited phosphorus removal and variability in COD reductions. The research provides valuable insights for designing efficient, sustainable leachate management strategies.

SOURCE: Wdowczyk, et al (2025) Assessment of changes occurring in biochar/zeolite substrates used in the vegetation-activated sludge process in the treatment of leachate from landfills. Water Resources and Industry. https://doi.org/10.1016/j.wri.2025.100280