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  • Treatment of Olive Oil Industry Effluents by Electrocoagulation
    Publication . Silva, Maria Fernanda Guapo da; Peres, António M.; Fajardo, Ana Sofia dos Santos; Sydney, Alessandra Cristine Novak
    The olive industry is one of the most economically significant agro-industrial sectors in the Mediterranean region, particularly in Portugal, one of the world’s leading producers and exporters of olive oil. The extraction process generates significant amounts of waste, namely olive mill wastewater and olive pomace (OP), which account for approximately 80% of the initial mass processed. OP is characterized by a high organic load, a recalcitrant lignocellulosic structure, and the presence of phytotoxic phenolic compounds, which pose a significant environmental challenge. This dissertation evaluated the feasibility of electrocoagulation (EC) in batch mode, using recycled aluminum electrodes produced from Computer Numerical Control machining metal shavings, for the treatment of diluted OP from a circular economy perspective. Despite the widespread application of EC in wastewater treatment, its direct application to OP extracts remains largely unexplored. Initial characterization revealed a moisture content of 64.2% and a total phenolic compounds (TPC) concentration of 4.9 mg gallic acid equivalents/g on a wet basis, compatible with two-phase extraction systems. The initial pH, current intensity, electrode spacing, and stirring speed were evaluated, while monitoring the removal of Chemical Oxygen Demand (COD), TPC, and UV-Vis absorbance (~225 nm), as well as energy consumption. The optimal conditions identified were pH 3, 0.25 A, a spacing of 1.0 cm, and 300 rpm. The most significant improvements occurred during the first 20 minutes of electrolysis, an operating point that allows for a ~33% reduction in energy consumption compared to 30 minutes, achieving COD and TPC removal rates of 38.7 ± 4.2% and 25.1 ± 2.8%, with a consumption of 3.5 ± 0.2 kWh/m³. The results demonstrate that EC using recycled aluminum electrodes constitutes a promising alternative for treating OP effluents, contributing to sustainable waste recovery strategies within the circular economy.
    2026Dissertação de mestrado Acesso embargado Ver mais