The work consists on the study of a sulphur–oxidizing bacteria (At. thiooxidans) immobilisation over polyurethane foam and the integration of two continuous processes: the solubilization of heavy metals by acidic medium generated by sulphur-oxidizing bacteria and the subsequent precipitation of metals as sulphides with H2S biologically generated by sulphate-reducing bacteria (Desulfovibrio sp). At. thiooxidans was satisfactory immobilised over polyurethane foam and added to a column reactor. Acidic medium generated was added to a column with 50 g of an artificial contaminated sand (85 mg Cr(III), 20 mg Ni(II), 200 mg Zn(II)). The effluent of this step was collected in a reservoir tank, in which H2S from sulphate-reducing reactor was included to carry out the precipitation of metals. After 2.4 l of acid medium was passed through the column, it was observed that 14.6% of Cr(III), 26.7% of Ni(II) and 90.5% of Zn(II) were solubilized. The leachate was treated with 2.2 l of reducing medium, and 2.2% Cr(III),54% Ni(II) and 28% Zn(II) were precipitated.