Removal performance of leonardite toward volatile organic compounds and toxic metals from landfill leachates

Leachate from municipal waste contains volatile organic compounds and potentially toxic metals. The leaching of which into water sources also jeopardizes access to clean water. Therefore, reducing the concentration of pollutants in leachate is important to reduce health risks and environmental pollution. In this study, the efficacy of granulated organic leonardite added to leachate from municipal waste in reducing the toxic concentrations of the leachate for different time points (30, 60, 90, and 120 min) at a shaking speed of 200 rpm was investigated. Results demonstrated that leonardite significantly removed various contaminants, including organic acids (71.16%), alcohols (74.31%), aldehydes (68.01%), esters (78.28%), ethers (81.03%), ketones (68.52%), hydrocarbons (84.25%), N compounds (78.56%), S compounds (80.67%), organic N (86.01%), total Kjeldahl nitrogen (93.26%), NH₄-N (84.83%), NO₃-N (89.30%), SO₄ (76.62%), PO₄ (73.85%), organic C (50.07%), Hg (96.80%), Pb (95.99%), Cu (82.68%), Al (65.56%), total Cr (98.11%), Cd (99.28%), Li (96.31%), Ni (97.27%), and As (67.79%). The leonardite granules used in this study showed high adsorption and removal performance for organic/inorganic and volatile compounds in landfill leachate. These results indicate that leonardite can be a suitable adsorption material for leachate pretreatment. However, it is necessary to perform a durability test to use the material in the long term as a covering on landfills.