RESUMO
Anaerobic sediments of urban watercourses are subjected to industrial pollution and frequently tend to accumulate heavy metals. The biocatalyzed oxidation and reduction of sulphur compounds that occur within the sediment are key reactions that determine mobility of metals such as that occurred in mine acidic drainage reactions. The aim of this work was to study the application of these processes using heap leaching technology for the remediation of anaerobic contaminated sediments from Reconquista River basin. The bioleaching potentiality for remediation was demonstrated through batch tests in shake flasks with different pulp densities of anaerobic sediment containing 338 mg kg-1 of Zn and 117 mg kg-1 of Cu. Subsequently, bioleaching heap systems were compiled into columns of 12-cm height and 6-cm diameter, fitted with perlite to improve drainage. In order to assess the effect of elementary sulphur over the mobility of metals from the bioheap to the aqueous solution, increasing concentrations of elementary sulphur (1, 2, 5 % w/w) were added. After 3 months of acidification generated by periodic watering, the extraction of 70 % of the initial Zn and 43 % of the initial Cu was achieved. Polluted sediments from waterways as Reconquista River should not be indiscriminately manipulated if acid drainage is possible. Remediation by a simple and economically viable strategy like heap leaching is feasible.
Assuntos
Recuperação e Remediação Ambiental/métodos , Sedimentos Geológicos/análise , Metais Pesados/metabolismo , Rios/química , Poluentes Químicos da Água/metabolismo , Anaerobiose , Argentina , Biodegradação Ambiental , Metais Pesados/análise , Poluentes Químicos da Água/análiseRESUMO
One of the problems in waste water treatment plants (WWTPs) is the increase in emissions of hydrogen sulphide (H2S), which can cause damage to the health of human populations and ecosystems. To control emissions of this gas, sulphur-oxidizing bacteria can be used to convert H2S to sulphate. In this work, sulphate detection was performed by spectrophotometry, ion chromatography and atomic absorption spectrometry, using Paracoccus pantotrophus ATCC 35512 as a reference strain growing in an inorganic broth supplemented with sodium thiosulphate (Na2S2O3·5H2O), sodium sulphide (Na2S) or sodium sulphite (Na2SO3), separately. The strain was metabolically competent in sulphate production. However, it was only possible to observe significant differences in sulphate production compared to abiotic control when the inorganic medium was supplemented with sodium thiosulphate. The three methods for sulphate detection showed similar patterns, although the chromatographic method was the most sensitive for this study. This strain can be used as a reference for sulphate production in studies with sulphur-oxidizing bacteria originating from environmental samples of WWTPs.