The aim of this study was to investigate the feasibility of a bioreactor system and its scale-up to remove Cr(VI) from solution. The bioreactor is based on an innovative process that combines bioreduction of Cr(VI) to Cr(III) by the bacterium Arthrobacter viscosus and Cr(III) sorption by a specific zeolite. Batch studies were conducted in a laboratory-scale bioreactor, taking into account different operating conditions. Several variables, such as biomass concentration, pH and zeolite pre-treatment, were evaluated to increase removal efficiency. The obtained results suggest that the Cr removal efficiency is improved when the initial biomass concentration is approximately 5 g L -1 and the pH in the system is maintained at an acidic level. Under the optimised conditions, approximately 100 % of the Cr(VI) was removed. The scale-up of the developed biofilm process operating under the optimised conditions was satisfactorily tested in a 150-L bioreactor.

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Neon (Ne) is an expensive noble gas with commercial interest, which is why systems for Ne storage and delivery are useful tools for its more efficient utilization. Although adsorption-based technologies are potential candidates for the development of such systems, there have been few research efforts on the study of Ne adsorption equilibria on porous solids. Metal−organic frameworks (MOFs) are a recent class of promising porous materials for adsorptive gas storage. In the present work, Ne adsorption in two of the most well-known MOF materialsHKUST-1 and UiO-66has been evaluated experimentally over unusually wide pressure and temperature ranges: 0−70 bar, 77−400 K for HKUST-1 and 0−100 bar, 77−500 K for UiO-66. HKUST-1 has higher Ne adsorption capacity per unit weight than UiO-66, whereas per unit volume the two materials perform similarly. Moreover, the isosteric heats for Ne adsorption on HKUST-1 and UiO-66 have roughly the same order of magnitude (3−6 kJ/mol).

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