In the present work, the influence of the competitive effect of inorganic ligands (carbonates, chlorides, fluorides, phosphates, nitrates and sulphates), which can be present in real multi-metal electroplating effluents, on the biosorption of chromium, copper, nickel and zinc ions by yeast cells of Saccharomyces cerevisiae was rationally examined. Additionally, chemical speciation studies allowed optimizing the amount of yeast biomass to be used in the treatment of effluents contaminated with nickel. The applicability of chemical simulation studies was tested using two simulated effluents and validated using one real electroplating effluent, all containing high concentrations of nickel (about 303 mu mol l(-1)). For nickel removal, heat-killed biomass of a brewing flocculent strain of S. cerevisiae was used, in a batch mode. After the implementation of the bioremediation process (12 g dry weight l(-1) of yeast cells), the concentration of nickel in the real effluent (34 mu mol l(-1)) reached the quality criteria for industrial effluents discharge, after the second or third batch according to the U.S.-Environmental Protection Agency and Portuguese law, respectively. This corresponded to a removal of nickel of 89%. (C) 2010 Elsevier B.V. All rights reserved.