E. PARAMESWARI, A. LAKSHMANAN AND T. THILAGAVATHI
Abstract
A study was carried out to assess the heavy metal (Cr (VI) and Ni) removal efficiency of Azotobacter chroococcum, Bacillus sp. and Pseudomonas fluorescens isolated from sewage and sewage irrigated soils. The optimum time for maximum metal removal (82.58 %, 89.50 % and 95.54 % of Cr, 86.16 %, 84.32 % and 90.98 % of Ni by A. chroococcum, Bacillus sp. and P. fluorescens respectively) was found to be 72 hours at an initial metal concentration of 25 ppm. While comparing the percentage uptake, more amount of Cr (VI) was absorbed than Ni by Bacillus sp. and P. fluorescens. The percentage of Cr (VI) and Ni removal decreased with increasing initial metal concentration. The uptake of Cr (VI) and Ni increased as the incubation period advanced. The bioacccmulation of heavy metals by these bacterial isolates was observed to be in the order of P. fluorescens > Bacillus sp.> A. chroococcum.