TECHNOLOGY FOCUS - BIOLOGY - Preferred Method: The method (M1) involves performing a pre-treatment of the FAU zeolite, by their calcination at 500degreesC during 6 hours under a dry air stream; growing the Arthrobacter viscosus bacterium in the presence of the pre-treated zeolite and in an adjusted and sterilized growth medium at 120degreesC during 20 minutes; and contacting the biosorbents with hexavalent chromium solutions (at concentrations of 50 - 250 mg chromium/l), prepared from potassium dichromate. The contact between the biosorbents is performed at 28degreesC in medium stirring. The recovery of the solid matrix is performed by, centrifugation at 5000 revolutions per minute. The recovery of the solid matrix, for later catalytical application, is performed by the removal of organic material of the Arthrobacter viscosus bacterium, by its calcination at 500degreesC during 6 hours under a dry air stream. EXAMPLE - A faujasite (FAU) zeolite was calcined at 500degreesC during 8 hours under a dry air stream. The preparation of biosorbent was carried out through the growing of the Arthrobacter viscosus bacteria in presence of pre-treated zeolite. For the microorganism growth, a medium with peptone (5 g/l), malt extract (3 g/l), yeast extract (3 g/l) and glucose (10 g/l) was prepared, previously sterilized at 120degreesC for 20 minutes. The Erlenmeyer flasks were kept at 28degreesC in moderate stirring. Adsorption tests were carried out using 1 g of the NaY or NaX zeolite with 150 ml of the different dichromate solutions having a concentration of 50 - 250 mg chromium (Cr)/l and 15 ml of Arthrobacter viscosus culture medium in 250 ml Erlenmeyer flasks at 28degreesC, in moderate stirring. Aqueous chromium solutions were prepared by, dilution of K2Cr2O7 in distilled water. The matrix obtained through centrifugation at 5000 revolutions per minute was subsequently calcined at 500degreesC during 6 hours under a dry air stream in order to remove the organic matter of the Arthrobacter viscosus bacterium, for a later catalytical utilization. The biosorption system was tested under conditions of low Cr concentration. 1 ml Samples were taken and were after centrifugation, analyzed by atomic absorption spectrophotometry for metal determination. It was observed that, a maximum efficiency of chromium removal was about 20%. The biofilm of Arthrobacter viscosus supported in X or Y zeolite presented removal capacity of chromium ions contained in weak solutions and were suitable for usage in bio-remediation. The reduction of Cr(VI) to Cr (III) was promoted by the biofilm, where Cr (III) retained in the zeolite by ion exchange.