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A biological method for the reduction Cr(VI), using sulphate-reducing bacteria (SRB), was tested in 2-L then 20-L fixed-bed reactors, with H2 as a low-cost and clean substrate. The systems were inoculated with Desulfomicrobium norvegicum, that proved to be particularly efficient for direct Cr(VI) enzymatic reduction. The bacterial reduction was efficient when some SO2−4 was provided in the feeding, in order to allow their growth and to combine the direct enzymatic reduction to the indirect chemical reduction by dissolved H2S. The Cr(VI)/SO2−4, ratio in the influent was adjusted in order to avoid excess sulphide production. A real polluted groundwater and an industrial electroplating effluent were treated in the 20-L pilot plant.