Associação de tratamentos físico-químicos para remoção de matéria orgânica e cor de chorume estabilizado produzido no lixão da cidade de Maceió/AL

Abstract

The sanitary landfill is the most used method for the final disposal of municipal solid wastes (MSW) in the world. As this waste is buried, it undergoes physicochemical and biological processes, causing degradation of the organic fraction, which combinated with percolating rainwater, results in a highly liquid called leachate. The treatment of this effluent is one of the challenges of managing MSW, since it presents characteristics of a potential polluter and besides of the difficult of treatment. In attempt to reduce the environmental problems caused by this leachate, researchers have been studying different treatment techniques. The choice of the appropriate technique depends on several factors, often requiring the association of more than one treatment in order to the final effluent quality to reach the required standards. In this study three physicochemical treatments were evaluated, separately and combined, in the removal of true colour and chemical oxygen demand (COD) of the leachate. The leachate samples were collected at the landfill of Maceió, whose characterization showed that it is a potential polluter, for this reason cannot be released into surface water receivers without previous treatment, with the possibility to generate large environmental impacts. These data also showed that this residue is recalcitrant due to the low BOD/COD ratio and high ammonium nitrogen concentration and, possibly, resistant to biological treatment. The physicochemical treatments studied (acidification, coagulation and activated carbon adsorption) showed to be able to remove a large portion of COD and colour of the leachate. The results from the combination of the three cases showed that for the levels used, all variables were significant on the measured responses. The combination of the processes that resulted in higher removal of organic matter and colour of the leachate occurred at pH 5, concentration of PAC of 500 mg/L and activated carbon concentration of 5.0 g/L. In this case, experimental removals of colour and COD were 99.9% and 88.1%, respectively, suggesting that the combination of treatments evaluated here is a promising alternative treatment for leachate from the waste in an advanced state of degradation.