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Hexavalent chromium has been commonly used in the steel, refractory, leather tanning, wood treatment, pigment and chemical industries 1. During the last few decades the uncontrolled release of industrial wastes has contaminated the soil and water with Cr(VI) throughout the world 2-5. Hexavalent chromium is a strong oxidizing species with toxic and carcinogenic influences on all living organisms, including human. Contact with Cr(VI) compounds over a prolonged period of time is a risk factor for developing lung cancer 6. Trivalent chromium Cr(III) is a common representative of chromium compounds and less harmful compared to Cr(VI) 7. Moreover, Cr(VI) penetrates into the cells via the sulfate transporters due to its structural and electrical similarity with sulfate ions, whereas, intracellular penetration of Cr(III) is rather not possible 8. Generally Cr(VI) is much more mobile in soil than Cr(III). The major Cr(VI) species include; chromate, bichromate and dichromate are thermodynamically stable over a large pH range in the environment and hardly absorbed onto soil colloids under alkaline to sub-neutral conditions. Therefore, Cr(VI) posing a threat to surface and groundwater quality 9,10. Batch sorption

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Abstract:The decolourization of Turquoise Blue HFG by immobilized cells of Lysinibacillus fusiformis B26 was investigated. Cells of L. fusiformis B26 were immobilized by entrapment in agar and calcium alginate matrices and attached in pumice particles. The effects of operational conditions (e.g., agar concentrations, cell concentrations, temperature, and inoculum amount) on microbial decolourization by immobilized cells were investigated. The results revealed that alginate was proven to be the best as exhibiting maximum decolourization (69.62%), followed by agar (55.55%) at 40°C. Pumice particles were the poorest. Optimum conditions for agar matrix were found: concentration was 3%, cell amount was 0.5 g and temperature was 40ºC (55.55%). Ca-alginate beads were loaded with 0.5, 1.0 and 2.0 g of wet cell pellets and the highest colour removal activity was observed with 2.0 g of cell pellet at 40ºC for alginate beads. Also, 0.5 and 1.0 g of pumice particles that were loaded with 0.25 and 0.5 g of cell pellets respectively were used and the results were found very similar to each other. Unauthenticated Download Date | 5/8/18 7:04 AM