Potencialidade da coagulação/floculação/decantação como alternativa de pós-tratamento de lixiviado de aterro sanitário

Abstract

The treatment of leachate is one of the biggest challenges in the operation of sanitary landfills, in view of its complex composition and seasonal variability. The generation and characterization of leachate can be influenced by climatological and hydrogeological factors, in addition to factors related to the cover layer, deposited waste and the type of landfill operation. In sanitary landfills, a set of biological and/or physical-chemical treatment techniques is often used in the treatment of leachate, aiming to fit it into the standards for releasing effluents into water bodies according to current legislation. The sanitary landfill in the city of Maceió-AL has an ETP composed of biological treatment processes (1 anaerobic lagoon, 2 pre-aerated lagoons and 1 optionally aerated lagoon) and physical-chemical processes (coagulation-flocculation-decantation, filtration and reverse osmosis). In view of this, the objective of this work was to study, on a bench scale, the treatment by coag-floc-dec of the biologically pre-treated leachate from the Maceió-AL landfill, using the same coagulant, with and without the anionic polymer as an auxiliary of flocculation, used in real scale. Monthly samples were analyzed, collected from Oct/22 to Feb/23 (totaling 4 collections), performing bench tests with different pH ranges x PAC dosages, at sedimentation velocities of 1 cm/min and 0.5 cm/min. In two collections, only the PAC was applied in the bench tests, and in the other two, the anionic polymer was tested together with the PAC. The physical-chemical parameters evaluated were pH, apparent color, turbidity, COD and N-ammoniacal. In general, the bench tests showed better performance with a sedimentation velocity of 0.5 cm/min and greater removal of physicochemical parameters using only the PAC. Throughout the analyzes using only the PAC, removal efficiency of up to 77% of apparent color and 94% of turbidity was verified. In the analyzes using the PAC in conjunction with the anionic polymer, there was apparent color removal efficiency of up to 41% and 85% of turbidity. As for COD and N-ammoniacal removal, the remaining samples evaluated, resulting from tests using only the PAC, demonstrated performance of up to 35% of COD removal and up to 48% of N-ammoniacal removal. In the remaining samples of the tests using the PAC in conjunction with the anionic polymer, there was a reduction of up to 35% of COD and 39% of N-ammoniacal.