Resíduos do processamento de sisal (Agave sisalana) como alternativa na remediação de solos contaminados com metais

Abstract

The presence of heavy metals in the soil is a subject of high interest due to environmental damage and the possibility of entering to the trophic chain. There are several techniques to remediate soils contaminated by heavy metals, and when residues generated on a large scale and without apparent useful, it is even more promising, due to the costs and less impact on the environment. The objective was to evaluate the solubility of Cd+2 and Pb+2 in the soil after addition of organic residues [mucilage (MUC), fibrils (FIB) e fiber powder (PFIB)] obtained from sisal processing. The experiment was conducted in a greenhouse under completely randomized design (DIC), in 4 x 3 factorial, with 3 repetitions. Soil samples, previously prepared, were contaminated with 30 mg kg-1 of Cd and 72 mg kg-1 of Pb. Residues were added to soil samples at a dose of 2%. The samples were collected from the unit pots 4 times, with an interval of 30 days between each collection and, CaCl2 0,01M L-1 solution was used as extractor for further quantification of metals by atomic absorption spectrometry. The results followed the sequence MUC>FIB>PFIB, in which in most cases the MUC and FIB did not differ statistically from each other, expressing at all times an efficiency greater than 90% in the adsorption of heavy metals. After 30 days it was possible to observe the efficiency of MUC and FIB, which adsorbed 98,72% and 95,82% of the Cd from soil, respectively, which corresponds to 11,57 mg kg-1 and 11,23 mg kg-1. There was a reduction in Pb solubility by MUC and FIB in 3,26 mg kg-1 and 3,23 mg kg-1 or 96,45% e 95,56%, respectively. The residues were effective in reducing the solubility of Cd+2 and Pb+2 in soils, thus demonstrating their potential in the biosorption of the evaluated metals and, consequently, in the reduction of their availability.