Bioremediation of Soil Contaminated with Tannery Effluent by Combined Treatment with Cow Dung and Microorganisms Isolated from Tannery Effluent

Bioremediation potential of a combination of cow dung and a microbial consortium (Pseudomonas aeruginosa, Penicillium chrysogenum and Aspergillus niger) in soil contaminated with tannery effluent, was investigated in the laboratory. Concentrations of phenol, sulphide and ammonium nitrogen in contaminated soil, were significantly reduced (P=0.000) to permissible levels after treatment with microbial consortium, cow dung or combination of microbial consortium and cow dung. Reduction of these compounds was best with combination of microbial consortium and cow dung. Cr (VI) level (139.2 mg/kg) was significantly reduced (P=0.000-0.050) by 33.2, 96.9 and 99.9% after treatment with microbial consortium, cow dung, and combination of consortium and cow dung, respectively. The treatments elevated soil pH from 5.8 to 6.9-7.2. Growth of maize in soil treated with the combination of microbial consortium and cow dung was not significantly different from growth in uncontaminated soil. Cr (VI) concentrations in the maize tissues were very low (0.002-0.006 mg/g). Thus combination of microbial consortium and cow dung may have potential application in bioremediation of soil polluted by tannery wastes.