Bioremediation of Cr(VI) polluted wastewaters by sorption on heat inactivated Saccharomyces cerevisiae biomass

The potential of heat inactivated Saccharomyces cerevisiae in the bioremoval and reduction of Cr (VI) ions from wastewaters was evaluated in terms of metal uptake in time and at equilibrium, and biosorption efficiency, by varying pH, biosorbent doses, contact time and temperature, in batch mode. During the sorption process, the heat inactivated biomass of the yeast Saccharomyces cerevisiae is capable of reducing Cr(VI) to Cr(III). Different kinetic models based on adsorption and reduction are used to represent the kinetic data of Cr(VI) bioremoval by S. cerevisiae, in explaining the biosorption mechanism of heavy metals and potential rate-controlling steps, in the perspective of full-scale process design. The results indicated some potential differences in the Cr(VI) removal mechanism at different experimental conditions. FTIR and SEM analysis were performed as well as to elucidate the mechanism of metal bioremoval by S. cerevisiae. FTIR spectra indicate that heavy metal bioremoval process doesn’t imply in this case the formation of stable covalent bonds, but it is predominantly based on chemical interactions, ion-exchange type. The SEM micrographs of Cr-loaded yeast, indicates that the surface morphology doesn’t change much after chromium ions were uptaken. This leads to the conclusion that Cr(VI) reduction occurs at the interface of the adsorbent.This paper was elaborated with the support of BRAIN project Doctoral scholarships as an investment in intelligence - ID 6681, financed by the European Social Found and Romanian Government and with the support of a grant of the Romanian National Authority for Scientific Research, CNCS - UEFISCDI, project number PN-II-ID-PCE-2011-3-0559", Contract 265/2011

Drépanocytose à l’âge adulte, mycoplasme et agglutinines froides, à propos de 2 observations

Le syndrome thoracique aigu (STA) est une cause de mortalité chez les patients drépanocytaires. Le diagnostic requiert une fièvre ou des symptômes respiratoires et une nouvelle condensation pulmonaire. Les causes, souvent intriquées, sont les infections, l’infarctus pulmonaire, l’hypoventilation et l’embolie graisseuse. Dans la population drépanocytaire pédiatrique, l’infection à Mycoplasma pneumoniae (MP) est souvent en cause [1], [2]. Cette bactérie est moins fréquemment évoquée chez les adultes que les germes encapsulés, redoutés chez ces patients hypospléniques. Nous rapportons 2 cas de pneumonie à MP chez des adultes drépanocytaires, associée à la présence d’agglutinines froides (AggF)