Remoção de chumbo, bário e zinco de um efluente aquoso via flotação por ar disperso

Abstract

Environmental pollution caused by heavy metals from different economic activities, including the oil wells drilling has been one source of soil contamination by lead, barium and zinc. These metals compose substances such as barita and galena, which are used to density control of drilling fluid. The soil remediation frequently uses EDTA (1.0 M) as extractor agent, which generates a large amount of concentrated liquid metals. The metals present in this aqueous solution are present at low concentrations (between 10-7 and 10-4 mols.dm-3), which can’t be removed by traditional methods. Alternatively, flotation treatment is a technique that has a viable capacity to handle large volumes of effluent in relatively small areas and accepts combinations with other techniques such as coagulation. This study aimed to verify the removal efficiency of Pb, Zn and Ba present in a synthesized solution, which simulates the effluent generated by contaminated soil washing, by dispersed air flotation. The experiments were conducted at bench scale and have been investigated the influence of the parameters involved in the process, such as pH, flotation time, column height and bubble size. All the study was done by colloid flotation using ferric chloride as coagulant and sodium dodecyl sulfate as the collector of a stoichiometric ratio of three sodium dodecyl sulfate to one of metal. The results showed that the technique has produced satisfactory results in the removal of lead, barium and zinc reached up to 100% removal of the metal, making it possible to meet criteria and standards for effluent discharge described in the RESOLUTION Nº. 357, THE NATIONAL COUNCIL ON THE ENVIRONMENT (CONAMA).