Aplicação de tratamentos eletroquímicos integrados para remediação de solos contaminados com metais e avaliação da toxicidade

The diffuse pollution and particularly the effects of this pollution on water reservoirs is becoming an issue of the major significance. Consequently, soil remediation is very promising area of study within environmental engineering and the development of novel and efficient treatment technologies (such as the electrochemically assisted technologies) is becoming more important. EK is an efficient technology for the removal of Pb from soils [1]. This work aims to use electrokinetic Remediation (EK) for removal lead in soil and evaluation of soil toxicity using as flushing agent. In the first case, were evaluated, the effect of chemical properties (facilitating agents, pH control by reversal polarity) in order to yield high removal levels at the end of treatment. The second aim was evaluated the toxicity of soil at the end of each treatments by cultivating helianthus annuus species because is used for biodiesel production and third, the treatment of the effluent generated during EK by electrocoagulation. The bench setup used in this work was constructed from transparent methacrylate and divided into seven compartments [2] and during the electrocoagulation experiments were performed using a single compartment electrolytic batch cell equipped with parallel plate Al electrodes with a nominal surface area of 50 cm2, applied 15 mA cm-2 at 90 min. The soil was contaminated with Pb at 1000 mg kg-1. During the EK, graphite electrodes were used, applying 1 V cm-1 in 14 d, and in order to optimize EK, was used solutions of NaNO3, EDTA, citric acid and application of polarity reversal, were tested. The combination of EK-EDTA with polarity reversal showed better results in short period (14d), in this case the removal was 73% of Pb in soil, when used only NaNO3 and citric acid 65 and 48%, respectively. The phytotoxicity levels of the soil treated with the electrokinetic remediation process with polarity reversal exhibits low levels of phytotoxicity, attaining similar germination index 89%, demonstrating that the soil can be used for plantation of helianthus annuus for biodiesel production. The complete elimination of Pb in solution was achieved, at all effluents demonstrating the possible reuse.