HEXAVALENT CHROMIUM DETOXIFICATION BY ALKALIPHILIC BACTERIA ISOLATED FROM TANNERY WASTE WATER IN LEBANONNARMIN ZMORROD, HALA S. MOUDALLAL, HODA YUSEF AND NAWAL AL HAKAWATIAbstract The present study deals with the application of Cr (VI)-resistant bacterial species in the bioaccumulation of Cr(VI) in alkaline growth conditions (pH 10). These bacterial species were isolated from wastewater samples collected from the outlet point of two leather tanneries in Saida, South Lebanon. The alkaliphilic isolates were investigated for Cr (VI) tolerance ability. Two bacterial isolates (A1 and A2) showed a maximum tolerance concentration (MTC) of 250 ± 0.0 and 50 ±0.0 mg L-1 of Cr(VI), respectively. The bacterial isolate (A1) with highest MTC to Cr (VI) was identified phylogenetically as Bacillus cohnii A1 (MK 478809). Mechanism of Cr (VI) accumulation by the living cells of B. cohnii A1 was investigated using Fourier Transform Infrared spectroscopy and Transmission Electron Microscopy. The optimization study revealed that the highest Cr(VI) removal from an aqueous solution of 10 mL volume was attained with a bacterial biomass of 0.1 g at pH 9. The bioaccumulation capacity and the kinetics of the process were determined. The effectiveness of the investigated Alkaliphilic B. cohnii A1 suggests its application in the in situ treatment of alkaline Cr (VI) polluted wastewater. |