Desempenho de um sistema com leito fluidizado de vermiculita expandida, para remoção de íons metálicos tóxicos presentes em efluentes industriais.

Abstract

Aiming at studying water contamination and its following problems this paper has sought to develop an alternative methodology to remove toxic cations from solutions with reference to its industrial effluents. At first, a characterization of the argilomineral vermiculita’s grain size was developed by analyzing the X-rays and in which the argillaceous material was thermally expanded and its predecessor, in natura, both presented crystallographic data that corroborate the mineral’s file. Further bench testing were carried out with synthetic solutions percolation of Cr3+, Cu2+ e Pb2+ in the VM expanded bed under six treatments kept under stirring for six hours. The adsorption capacity and ionic exchange was proved in which the maximum removal was 97,11% of Cr3+; 93,06% for Cu2+ and 96,28% for Pb2+. A prototype was developed and named SATIFIC in order to carry out bigger scale experiments (200,0 L), in which the residence time distribution was studied on the fluid particles bringing into evidence that the average residence time grew as the mass was increased at the bed spurt, or even when the fluid’s flow was decreased. The SATIFIC monitoring was done within collecting periods during 24h under a batch processing in order to remove the chrome ions, copper and lead, all present in water solutions with 100,0 mg.L-1 concentrations. The Cr3+ cations had bigger removing indexes, followed by the Cu2+ ions and reached the launching limit for effluent (LLE), referred by the current law with beds m2 (2.800,0 g) and m3 (4.200,0 g); while the Pb2+ species only reached the admissible goal with bed m3. With the saline mixtures, just Cr3+ reached LLE with m2, and as for m3 bed the removal occurred in admissible levels for three cations in the following order: Cr3+ > Cu2+ ≥ Pb2. . At last, in order to avoid a secondary pollution, there was the encapsulation of the contaminated vermiculita with toxic residue. Specifically for the Cr3+, it was allotted a cement block production by solidification and stabilization process with four different traces, being approved according to their mechanical features, mainly according to the higher amount of cement and other additions. By leaching out extracts it was possible to identify the blocks that could be classified as non-hazardous residual products, validating them for a daily basis use whenever idle by solubilization process.