Tratamento de lixiviado de aterro sanitário por coagulação/floculação

Abstract

The physical, chemical and biological degradation of the organic matter present in solid wastes generates a highly polluting by-product called leachate. Due to the concentration of ammoniacal nitrogen, the organic matter is biodegradable and the compounds are recalcitrant, the chemical-physical processes are being studied as complementary alternatives for the biological treatment of effluent. Thus, this work had as objective to evaluate the efficiency of the coagulation / flocculation process regarding the removal of organic matter present in biologically pretreated leachate, using vegetable tannin and aluminum polychloride as coagulants. The leachate was collected at the landfill located in Sorriso - MT, at the exit of the facultative lagoon. The characterization of the leachate was performed by determination of the parameters, turbidity, chemical oxygen demand (COD), electrical conductivity, total suspended solids (SST), Kjedahl nitrogen, pH, UV254nm and total phosphorus. The effluent coagulation / flocculation / decantation tests were performed at three different pH values (5, 7 and 9); Two coagulants, one chemical, aluminum polychloride (PAC) and one natural, Tanfloc, and an anionic polymer were used as flocculation aid; Eight dosages of coagulant; And three decanting times. The values were obtained with turbidity, pH, volume of sludge, color and UV254nm. (> 92%) and pH 5 and 7 for the coagulant PAC (> 95% and> 97%, respectively). The coagulant PAC had the best color and UV254nm removals, and no color removal of 100% was removed at pH 5.0 at 750 mg.L-1 . Decantation time between 20 and 60 minutes did not significantly alter the results; The polymer as a coagulation aid does not contribute significantly to the removal of turbidity. The maximum volume of sludge produced was 680 mg.L-1 , indicating that the flakes had low density. The results show that coagulation / flocculation treatment can guarantee high removals of turbidity, color and UV254nm, which demonstrate a removal of dissolved and suspended matter in the effluent.