Avaliação da eficiência do processo avançado de oxidação para remediação de solo contaminado por BTEX

Abstract

Over the past few years, cases of soil contamination by hydrocarbons derived from petroleum, such as BTEX (benzene, toluene, ethylbenzene and xylenes), have become increasingly recurrent. This fact arouses great concern among specialists in view of the complexity and specificity of action of this environmental compartment, as well as the polluting potential intrinsic to this group of organic pollutants that are part of the soluble fraction of fossil fuels. Physical, chemical and/or biological remediation measures are normally applied to contain or eliminate the contamination plume formed after the percolation of contaminants through the subsoil. In view of the above, the present work aims to evaluate the efficiency of an advanced oxidative process, from the English Advanced Oxidation Processes (AOP), using sodium persulfate isolated and combined with hydrogen peroxide as an oxidizing agent, with emphasis on the treatment of BTEX present in soil contaminated with gasoline. A sandy loam soil, in the metropolitan region of Curitiba, free of the target contaminants of the research was collected and then contaminated in the laboratory. After the contamination process, the soil was subjected to a remediation test in batches with sodium persulfate in different molar ratios, with isolated systems with persulfate/BTEX (PER 20/1 and PER 100/1) and combined systems with H2O2/persulfate/BTEX (COMB 0,2/20/1 and COMB 1/100/1). It was possible to observe that after the oxidation tests, there was a reduction in the mass of the contaminants in 98.38% for the tests in the PER 20/1 condition and 95.37% in the COMB 0.2/20/1 condition. For tests under PER 100/1 and COMB 1/100/1 conditions, there was a 100% reduction in BTEX mass. The contaminated soil samples before and after the AOP were submitted to ecotoxicological tests with Lactuca sativa seeds and evaluation of the oxidant content that composed the quality parameters for the treatments, the results of this, therefore, show that the best evaluated treatment corresponds to the PER 20/1 system (20 moles of persulfate for 1 mole of BTEX), since there was less oxidant consumption and the lowest phytotoxicological adverse effect evaluated. The combined systems did not show a significant improvement in the isolated action of persulfate under the evaluated conditions.