Adsorção de amônia e matéria orgânica de lixiviado de aterro sanitário em diferentes materiais adsorventes

Abstract

Landfills, although a low-cost alternative for the disposal of solid waste, generate leachate rich in ammonia and organic matter. If not properly treated, this effluent can cause serious environmental and public health impacts, mainly due to the high oxygen demand required for the degradation of its contaminants. Studies indicate that the complexity of leachate, containing dissolved organic matter, inorganic salts, and heavy metals, reduces the efficiency of conventional treatments. In this context, this study aimed to investigate the adsorptive capacity of residual sludge from Water Treatment Plants (WTP) for the removal of N-NH4+ and COD from landfill leachate, in comparison with activated carbon and clay. For this purpose, adsorption tests were conducted under controlled conditions, comparing the efficiency of the adsorbents in removing N-NH4+ and COD. The results showed that activated carbon exhibited significantly higher efficiency in removing NH4+ in a simple solution compared to the removal of N-NH4+ from landfill leachate. However, in the leachate, the WTP sludge demonstrated a 20% removal of NH4+ in 3 hours, surpassing the result of activated carbon (18.2%). COD removal followed a similar trend, although it was less efficient than N-NH4+ removal among the three adsorbents under the different conditions analyzed, possibly due to the molecular complexity of the organic substances present in the leachate. The analyzed data suggest that residual WTP sludge is a promising alternative for the treatment of landfill leachate, requiring further studies to investigate all the characteristics that may influence the adsorption process, as well as offering a sustainable solution for the reuse of this residue, which is usually discharged into water bodies or landfills.