Cultivo de bactérias redutoras de sulfato (BRS) e sua aplicação na biorremediação de efluentes ácidos contendo metais

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Sulfate Reducing Bacteria (SRB) can be used as a promise and attractive biotechnology based alternative to promote passive treatment of industrial effluents. Sulfate is reduced to sulfide while organic matter is oxidized producing carbonate and bicarbonate ions. Treatment efficiency however depends on pH and metals content of the selected effluent and also on the quantity of organic matter available in the system (measured by means of COD-Chemical Oxygen Demand). As the COD/sulfate ratio varies, there are also different sulfate consumption degrees. It is commonly assumed that the optimal COD/sulfate ratio is approximately 0.67. The aim of this work was to optimize the growing and sulfate reduction capacity of mixed bacterial cultures obtained from different natural environments. Samples were cultured in batch reactors using liquid Postgate C medium containing sodium sulfate, 3.0 gL-1, different pH values (5.5 and 7.0) and different electron donors (sodium lactate and ethanol) at 35oC. In some experiments it was also added copper (10 and 20 mgL-1), manganese (10 and 20 mgL-1) and nickel (20 and 50 mgL-1) in order to study bacterial resistance to these metals. Lactate growing samples promoved pH neutralization and shown the capacity of reducing 43% of the initial sulfate content. Maximum sulfate reducing performance (98%) was achieved by the sample cultured in lactate containing medium, pH 7.0. However, when growing with ethanol as organic carbon source a sulfate reduction of about 50% was achieved. Production of acetate was observed as a consequence of the oxidation of both, lactate and ethanol. The obtained results shown that, under the experimental conditions adopted, sodium lactate was more efficient in promoting biological reduction of sulfate and neutralizing the pH of the medium when compared to ethanol. In addition SRB could be potentially used for reducing sulfate from acid wastewaters even though metals are present.

ASSUNTO(S)

metais biohidrometalurgia saneamento ambiental bactérias - sulfato biorremediação

ACESSO AO ARTIGO

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