Degradação e avaliação do potencial de toxicidade de compostos químicos presentes em lixiviado de aterro sanitário

Abstract

The increasing production of municipal solid waste (MSW), projected to reach 2.59 billion metric tons by 2030, coupled with inadequate landfill management, results in serious environmental and public health issues due to the toxicity of chemical compounds present in leachate. The Fenton oxidation process is known for its effectiveness in removing organic matter from leachate, but it faces significant challenges in mitigating the toxicity of the chemical compounds present. This study aims to develop degradation pathways for the chemical compounds found in landfill leachate to evaluate whether there was an attenuation of toxicity after Fenton treatment, providing insights for optimizing the treatment process. The leachate used was collected from the Puxinanã landfill and subjected to the Fenton treatment process. The chemical compounds present in both raw and treated leachate were identified by gas chromatography-mass spectrometry. The toxicity of the compounds was assessed by computational molecular modeling, using specific software and literature data available on PubChem. The results indicated that many compounds in the treated leachate exhibited toxicity, with transformation products (TPs) being more toxic than their precursor compounds. Molecular modeling revealed that all compounds had high Log Kow values, indicating their lipophilicity, and low Log S values. Compared with literature data, the TPs showed greater toxicity than the precursors. Based on the data, the Fenton process was not sufficient to attenuate the toxicity of the leachate, failing to effectively degrade some persistent compounds that maintained or increased their harmful potential. The degradation pathways developed allow for a more critical evaluation of the reactions occurring during the Fenton process, considering both TPs and generated intermediates. This paves the way for optimizing the process and underscores the need for improvements in MSW management and the remediation of environmental and public health damages caused by landfill leachate.