Navegando por Palavras-chave "Electrokinetic"

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    Oxidação química e eletrocinese na remediação de LNAPL em latossolo vermelho
    (Universidade Federal de São Paulo, 2016-08-11) Silveira, Lilian Puerta Machado [UNIFESP]; Freitas, Juliana Gardenalli de [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Recently, the combination of technologies (termed ?treatment trains?) has been used for remediation of complex contaminated sites, such as when the aquifer is heterogeneous, has low hydraulic conductivity, excess of organic matter and/or presence of different contaminants. In this context, the technologies of chemical oxidation and electrokinetics are being tested in combination aiming to increase the remediation´s efficiency. To test these two tecniques for LNAPL remediation, individually and combined, 15 tests were conducted in a two-dimensional model. Persulfate injection was simulated with different concentrations within the saturated zone and the capillary fringe, with and without electrokinetics application. An inert media (glass beads) and a reactive media (typic hapludox) were used. The results indicated that the difference in solute transport between the saturated zone and the cappillary fringe is only at the plume velocity, which is lower in the capillary fringe because the pores are not 100% saturated, reducing the hydraulic conductivity. It was verified that persulfate concentration affects its vertical migration as a function of the density of the oxidant and, therefore, this can be manipulated according to the goal of the LNAPL or DNAPL remediation. The tests with electrockinetics indicated that due to electromigration, the combined techniques may potentially transport solute to the areas of interest, accelerate the migration and reduce dispersion, driving the solute transport. It was also verified that this tecnique can be applied in a variety of soils, not only clayey soils, as long as the electrolyte has sufficient electric conductivity. In LNAPL remediation concentrations decreased in the dissolved, the sorbed and the free phase, with both isolated and associated techniques. However, chemical oxidation promoted the greatest degradation. Electrokinetics was capable of desorbing toluene from the soil and promoting its transport towards the cathode by electroosmosis. The main pollutant degradation processes were identified, although the mass balance indicated that other unknown processes might have occurred. The tests demonstrated that the remediation tecniques can alter some physical properties such as hidraulic conductivity by chemical oxidation and clay dispersion and soil consolidation by the electrokinetics. When the tecniques were associated those effects were even more significant. With respect to the chemical properties of the media, it was noticed changes in the predominant charge on the soil surface, pH decrease, mineral dissolution, organic matter degradation and change in the cation composition in the soil surface. These changes were more significant in the saturated zone test when compared to the capillary fringe test, and in the electrokinetics compared to the chemical oxidation. These results show the need to perform more studies before the implementation of a remedition tecnique, so that it is applied in the best way and it is possible to predict the negative effects and, when possible minimize them.