RESUMEN
The immobilization of Saccharomyces cerevisiae NRRL 567 biomass has been used to demonstrate its potential for removal and recovery of chromium ions from waste water streams. The immobilization process was carried out using three different immobilizing agents namely; Ca alginate, polyacrylamide and silica gel. Tris-HCI [pH 7.2] was the most suitable buffer for chromium removal on using the tested immobilizing agents. Ca alginate 3%, at residence time 30 min offered high removal of chromium ions [81.1%]. However, silica gel was found to be the best immobilizing agent, since 91.6% of chromium ions were removed. Furthermore, on increasing the dry weight of the used S. cerevisiae up to 50 mg/ml of the buffered chromium solution, the amount of the removed chromium ions reached about 97%. Elution of loaded chromium ions from the yeast cells immobilized on silica gel was successively achieved using 1% EDTA solution. Similarly, HCI and H[2]SO[4] solutions were found to be efficient in releasing chromium ions