Tratamento de lixiviado de um aterro sanitário por adsorção em cerâmica e processo Fenton

Abstract

The landfill leachate, popularly known as leachate, has a high concentration of organic matter, humic substances, ammoniac nitrogen and toxic compounds, generally requiring a combination of physical, chemical and biological treatment techniques to meet current release standards. The objective was to evaluate the treatment of leachate from a landfill by adsorption in clay pottery and by Fenton process. Initially evaluated in an isolated way, to obtain the best operational conditions, and later in a combined manner, in order to prove the high efficiency of these techniques when optimized. The clay pottery was use as adsorbent and the results were compare with those obtained by activated carbon, since it is a material already consolidated for this purpose. Both adsorption and Fenton were run in a shaker table with constant agitation of 150 rpm, temperature of 25 ° C and maximum reaction time of 140 min. The rotational central composite (CCR) delineation technique was use to optimize the response factors. In the clay ceramics, the granulometry was varied between diameters from 9.52 mm to 0.149 mm and masses from 5 g to 25 g. For the activated carbon the particle size was constant of 0.5 mm and the masses used ranged from 7 g to 23.5 g. The Fenton process had the optimum hydrogen peroxide concentration (H2O2) and the reaction time, and the starting point was relate to the stoichiometric amount of O2 required for the total COD stabilization. In the raw slurry the organic matter concentration in terms of COD was 2495 mg L-1, 1588 mg L-1 of ammoniac nitrogen, pH 7.84, phosphorus 59.20 mg L-1 among others. The clay adsorption gave a color removal efficiency greater than 55%, favored by particles with diameters of less than 2.53 mm and mean reaction time in 90 minutes. Activated carbon reached an efficiency of 80% of COD removal, with a mass of 20 g of adsorbent and an ideal time of 90 minutes. In the Fenton process, an efficiency of 82% of COD removal was obtained in a time of 45 min, with the ideal concentration of hydrogen peroxide being 22.5 mg L-1. Through the kinetic studies, it was possible to obtain the best condition for the use of the adsorbent and the Fenton process. In the combination of Fenton processes and adsorption with both adsorbents, the treatment achieved an overall efficiency of 90% COD removal. Therefore, concluded that the established treatment is promising for this effluent, but there is a need for complementation with other treatment techniques.