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Browsing by Author "Monteiro, Vanda Liliane Tavares"

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  • Optimising landfill leachate treatment: integrated coagulation/flocculation and fenton approaches
    Publication . Monteiro, Vanda Liliane Tavares; Martins , Ramiro
    The continuous accumulation of municipal solid waste in landfills has resulted in the generation of significant volumes of leachate, a complex and highly contaminated liquid effluent. This leachate is typically enriched with high concentrations of organic matter, ammonia nitrogen, heavy metals, and recalcitrant compounds such as humic and fulvic acids, which collectively confer low biodegradability and considerable variability in composition. These characteristics pose substantial limitations to conventional treatment technologies, often resulting in inefficient pollutant removal. Due to its potential to cause severe environmental contamination of soil and water bodies, the implementation of advanced and economically feasible treatment solutions is imperative. This study proposed and evaluated an integrated two-stage treatment strategy designed to enhance the efficiency of landfill leachate remediation processes. The proposed treatment procedure was initiated with a coagulation–flocculation (C – F) pre-treatment designed to promote the aggregation and subsequent removal of suspended solids and colloidal organic matter, thereby reducing turbidity and the initial organic load. This step was succeeded by an advanced oxidation process (AOP) based on the Fenton reaction, which relies on the in-situ generation of hydroxyl radicals (•OH) to oxidise refractory organic constituents. Following the C – F stage, a marked reduction in chemical oxygen demand (COD) and a concomitant increase in five-day biochemical oxygen demand (BOD₅) were observed, resulting in a significant improvement in the COD/BOD₅ ratio, a critical parameter for assessing effluent biodegradability. Process optimisation was conducted using Minitab® software, identifying the optimal Fenton conditions at pH 3.4, Fe²⁺ dosage of 8.96 g L-1, and H₂O₂ (30% w/w) volume of 30 mL L-1 of leachate. Under these conditions, the COD removal efficiency reached approximately 92%, and the COD/BOD₅ ratio increased from 0.053 to 0.87, indicating a substantial enhancement in biodegradability. The integration of physicochemical and oxidative processes has demonstrated high efficacy in mitigating the complex pollutant matrix of landfill leachate, offering a technically robust and environmentally sustainable strategy for effluent management. The goal was to propose a comprehensive and efficient solution for managing this effluent, supporting environmental sustainability and public health protection.
    2025Master thesis Open access Show more