Tratamento e toxicidade de lixiviado de aterro sanitário

Abstract

Urban solid waste must be disposed of in sanitary landfills, which is an appropriate form of final disposal of waste, as it provides for the capture of gases and leachate generated by the decomposition of waste. The slurry plus rainwater that infiltrates and percolates through the mass of waste generates the effluent called leachate. Due to the characteristics of the waste disposed of in the landfill, the leachate has a high polluting potential, and to be disposed of in the environment it needs treatment. This research aimed to evaluate the treatment of biologically treated landfill leachate effluent by coagulation/flocculation. In the treatment, coagulants PLC 115, PLC 120, PLC 2000, PLC 8030, PLC 8034 and Tanfloc were used, in dosages of 0, 800, 1600, 2400, 3200 and 4000 mg L-1. The treatment was evaluated by measuring the parameters pH, color, turbidity, ultraviolet absorbance at 254 nm (abs UV), biochemical oxygen demand (COD) and sludge volume. Considering the results obtained, the optimal dosages were defined for each coagulant to carry out the toxicity test with Artemia fransiscana. The results showed that the coagulant polyaluminium chloride PLC 115 was the most efficient among those analyzed when used at a dosage of 4,000 mg L-1, with removals of 62% for the color parameter, 84% for turbidity, 40.5% for abs UV and 29% for COD. Toxicity results in Artemia fransiscana showed that the LC50 was 63% for PLC115, PLC 120 and Tanfloc; 68.4% for PLC8030 coagulant and 85% for PLC8034 coagulant. After treatment by coagulation and flocculation, it can be seen that the effluent with less toxicity was treated with PLC 8034, unlike the results obtained for the removal of the other evaluated parameters, which show treatment with PLC 115 as more efficient.