Remediação de áreas contaminadas com metais pesados utilizando Acidithiobacillus sp. / Soil remediation with heavy metals using Acidithiobacillus sp.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The "Lake Region" of Santa Gertrudes is one of several contaminated sites with heavy metals in São Paulo State, Brazil. As in other regions of this country, in the 1970s the ceramic industries of Santa Gertrudes disposed their solid wastes and wastewaters directly in soil and contaminated an area of 1.5 km2. Biological solubilization of lead (Pb) and zinc (Zn) from soil of the Lake Region was tested in batch reactors. The biological process used the leaching capacity of Acidithiobacillus ferroxidans and Acidithiobacillus thiooxidans. Tests were performed to determine the influence of initial pH, the percentage of inoculum and the addition of nutrients on the efficiency of removal of these metals. The soil contained high concentration of iron oxides (8.3 %) and aluminum (16.8 %), clay (57 %), lead (717 mg/kg) and zinc (181 mg/kg). It was not necessary to reduce the initial pH of soil. Solubilization of lead (up to 3.6 mg/L) and zinc (up to 50 mg/L) was obtained, but the solubilization of Pb was low, probably because the element was precipitated as PbSO4. The solubilization of zinc was strongly correlated with the release of H+ ions produced from nutrient dissociation, particularly FeSO4, which promoted the acidification of solution. Although chemical solubilization was the main mechanism of Zn removal, biological solubilization by indigenous Acidithiobacillus ferroxidans was detected, reaching up to 17 % of the total element leached after 10 days of testing.

ASSUNTO(S)

zinc tropical soil lead chumbo leaching solo tropical zinco contaminação lixiviação contamination

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