Characterization of sludge generated from the treatment of sanitary landfill leachate with tannin-based coagulant

The aim of this study was to characterise the sludge resulting from the leachate treatment generated at sanitary landfill with tannin-based coagulant, denominated Tanfloc SG supplied by TANAC SA Company. The effluent treatment was performed at pH 7.4 and [Tanfloc SG] = 2700 mg/L, considered as optimum condition in COD and turbidity removal, however. Metal fractionation chemical analyses were done through simple and sequential extractions, with results indicating the solid residue is constituted by 29% of amorphous oxide, 28% of final residue, 22% of crystalline oxide and 21% of exchangeable fraction. The leaching tests have shown the sludge originated by Tanfloc SG treatment is classified as Class I residue - considered dangerous, according to Brazilian legislation (NBR 10.004/2004 - ABNT), indicating that such residues need to be treated and must be disposed in industrial landfills, for being a hazardous material due to its toxicity.