Aims:The aim was to investigate the biosorption of chromium, nickel and iron from metallurgical ef¯uents, produced by a steel foundry, using a strain of Aspergillus terreus immobilized in polyurethane foam. Methods and Results: A. terreus UFMG-F01 was immobilized in polyurethane foam and subjected to biosorption tests with metallurgical ef¯uents. Maximal metal uptake values of 164á5 mg g)1 iron, 96á5 mg g )1 chromium and 19á6 mg g )1 nickel were attained in a culture medium containing 100% of ef¯uent stream supplemented with 1% of glucose, after 6 d of incubation. Conclusions: Microbial populations in metal-polluted environments include fungi that have adapted to otherwise toxic concentrations of heavy metals and have become metal resistant. In this work, a strain of A. terreus was successfully used as a metal biosorbent for the treatment of metallurgical ef¯uents. Signi®cance and Impact of the Study: A. terreus UFMG-F01 was shown to have good biosorption properties with respect to heavy metals. The low cost and simplicity of this technique make its use ideal for the treatment of ef¯uents from steel foundries.

A full factorial design leading to 20 sets of sorption runs was conducted to study the influence of four variables (bleaching earth and biomass concentrations, pH, and sorption time) on the iron, nickel, and chromium removal from stainless steel effluent using waste biomass from a beverage industry. Similar factor effects and interactions were found for each metal involved in this biosorption study, and the main factors were pH (positive effect) and biomass concentration (negative effect). Response surface methodology was adopted and an empirical linear polynomial model constructed on the basis of the specific uptake (mg of metal/g of biomass as dryweight) for each metal species. Under optimized process conditions (pH 4.0, biomass concentration of 2.0 g/L, absence of Celite), uptake values of 155 mg of Fe/g, 38 mg of Cr/g, and 0.4 mg of Ni/g were achieved after 3 h. This corresponded to a reduction in heavy metals concentration of approx 94% for Cr, 57% for Fe, and 25% for Ni.

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