The performance of two bacteria, Arthrobacter viscosus and Streptococcus equisimilis, and the effect of the interaction of these bacteria with four different clays on the retention of diethylketone were investigated in batch experiments. The uptake, the removal percentages and the kinetics of the processes were determined. S. equisimilis,by itself, had the best performance in terms of removal percentage, for all the initial diethylketone concentrations tested: 200, 350 and 700 mg/L. The uptake values are similar for both bacteria. A possible mechanism to explain the removal of diethylketone includes its degradation by bacteria, followed by the adsorption of the intermediates/sub-products by the functional groups present on the cells surfaces. The assays performed with bacteria and clays indicated that the uptake values are similar despite of the clay used, for the same microorganism and mass of clay, but in general higher values are reached when S. equisimilis is used, compared to A. viscosus. Kinetic data were described by pseudo-first and pseudo-second order models.The authors would like to gratefully acknowledge the financial support of this project by the Fundacao para a Ciencia e Tecnologia, Ministerio da Ciencia e Tecnologia, Portugal and co-funding by FSE (programme QREN-POPH). Cristina Quintelas thanks FCT for a post-doc grant. The authors would like also to thank Minas de Barqueiros, S. A., Prof. Rui Boaventura (FEUP-Portugal) and Prof. Isabel Correia Neves (Dep Quimica, UM, Portugal) who gently offered the clays
