Organic matter removal from landfill leachate by adsorption using spent coffee grounds activated carbon

This study aimed to treat landfill leachate using spent coffee grounds (SCG) activated carbon, determining its efficiency for organic matter and color removal, as well as its maximum adsorptive capacity. Synthetic leachate containing only hunk acid and ammonium chloride was used in adsorption batch tests to determine the experimental conditions (adsorbent dose, pH, temperature, and contact time) favoring chemical oxygen demand (COD) and color removals. SCG activated carbon was also tested for real leachate treatment. The samples were prepared by impregnating SCG with phosphoric acid (H3PO4) at the ratios of 50 and 100%. Afterwards, the samples were submitted to pyrolysis (350 and 500 degrees C) at an inert atmosphere (N-2 at a flow rate of 0.1 L/min), for an 1-h period. The results indicated that samples impregnated at 50% presented higher surface areas (300-2118 m(2)/g) compared to those impregnated at 100% (188-1209 m(2)/g). The most efficient sample was produced at an impregnation ratio of 50% and at a pyrolysis temperature of 500 degrees C. Its maximum adsorptive capacity was 40 mg of COD per gram of activated carbon. In addition, outstanding performances were observed for real landfill leachate treatment, as >90% of color and COD were removed, proving the efficiency of SCG activated carbon not only for synthetic wastewater, but also real leachate. (C) 2019 Elsevier B.V. All rights reserved.