Desenvolvimento de processos eletroquímicos e combinados para a remediação de efluentes e solos contaminados com compostos organo-halogenados

Abstract

The growing concern of society with environmental risks and public health has required a more rigorous control of our waters and soils, promoting the development and implementation of new treatment technologies. Therefore, the present aimed to evaluate the decontamination of Persistent Organic Pollutants (POPs), specifically organohalogenated dyes and pesticides, in effluents and soils by the application of electrochemical processes using Boron Doped Diamond (BDD) anodes. The results of electrolysis with BDD anodes of a synthetic effluent contaminated with the Bromophenol blue textile dye clearly demonstrated that the application of different current values (1A, 2A, and 3A) was shown to be quite efficient because it not only reduces the color of the effluent, as well as lead to its complete mineralization. The significant concentration of Brreleased during the attack of the ●OH radical on the dye and the formation of the BrOspecies generated from the Anodic Oxidation of these anions explain the optimal performance of this technology in the treatment of synthetic solutions. The studies involving the decontamination of soil contaminated with the herbicide Clopiralida showed that it is possible to combine the dechlorination process with Zero Valent Iron (ZVI), soil washing and electrochemical oxidation in a single treatment sequentially or integrated in the same reactor. Therefore, Clopyralide was efficiently removed from the soil, and complete degradation of the pollutants in the wash fluids was possible using anodic oxidation with BDD electrodes in all studies. The dechlorination with ZVI integrated into the washing process had an important impact on the efficiency of the process, leading to less hazardous wastes (from the point of view of toxicity), but at the same time the intermediates formed are less oxidizable than the initial chlorinated compounds, which results in a less efficient process from the point of view of mineralization. This negative impact on the efficiency of the electrochemical process is not completely undesirable, because as the toxicity of the residues decreases significantly in the initial stages with the use of iron, it becomes promising the combination of this technology with biological treatments.