Landfill leachate treatment by waste-derived activated carbon

This research evaluated the use of spent coffee grounds (SCG) and oat hulls as precursors for activated carbon applied for organic matter removal from leachate, a pollutant wastewater produced by landfills. These precursors were selected based on their global commercial significance. The high demand for the beverage coffee is directly proportional to the generation of SCG as organic waste. Similarly, oat is a popular cereal consumed worldwide, and its industrial processing generates hulls as organic waste. The activated carbon samples were produced by chemical activation with phosphoric acid (H3PO4), using distinct impregnation ratios: 50 and 100 % for SCG, and 60 and 100 % for oat hulls; followed by pyrolysis in an inert atmosphere, at 350 and 500 °C. The feasibility of the tested precursors as adsorbents was initially assessed in experiments with synthetic leachate. Afterwards, the results from the initial tests were compared with those obtained in real leachate treatment. The studies described in this thesis showed that the impregnation ratios and pyrolysis temperatures interfered with the surface areas of the formed adsorbents, consequently affecting the organic matter removal from leachate. Both oat hulls and SCG were successfully recovered as activated carbon, and efficiently treated synthetic and real leachate, removing more than 90 % of the organic matter. Therefore, this study highly encourages the use of SCG and oat hulls as precursors for activated carbon production and their application to treat leachate.