Removal of Chromium (VI) by Bacillus subtilis Isolated from East Calcutta Wetlands, West Bengal, India

Abstract

Chromium (VI), one of the major pollutants released from tanneries, dye and textile industries, is highly toxic and carcinogenic in nature. Chemical methods for bulk treatment of industrial effluents often fail to reduce the level to meet the environmental regulations. For end of the pipe treatment, bioremediation is considered a better alternative. East Calcutta Wetlands, the major sewage treatment site of Kolkata (previously known as Calcutta), has been reported to be contaminated with several heavy metals including chromium (VI). Therefore, there is a possibility that bacterial population of this region can tolerate chromium (VI) and would be useful for bioremediation of chromium (VI). A strain of Bacillus subtilis isolated from this region was grown in presence of chromium (VI) (2.5 g/L–7.5 5 g/L). There were 97% and 90% reduction of residual chromium concentration in growth media after 24 hours with initial concentrations of 2.5 g/L and 5 g/L respectively. Best removal was observed at 30C. Growth of the Bacillus strain in presence of chromium (VI) was found to be best fit for Tessier model by non-linear regression analysis using MATLAB® 7.4. The Bacillus strain has the potential for the end of the pipe treatment removal of chromium (VI).