Bioleaching of spent Ni-Cd batteries and phylogenetic analysis of an acidophilic strain in acidified sludge |
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Authors: | Zhao Ling Wang Liang Yang Dong and Zhu Nanwen |
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Institution: | (1) School of Environmental Science and Engineering, Shanghai Jiaotong University, Shanghai, 200240, China |
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Abstract: | Biohydrometallurgy is a novel method to recycle discarded batteries, in which sewage sludge is used as microorganisms and
culture due to the presence of indigenous Thiobacilli. A two-step continuous flow leaching system consisting of an acidifying reactor and a leaching reactor was introduced to
achieve the bioleaching of spent nickel-cadmium (Ni-Cd) batteries. The acid supernatant produced in the acidifying reactor
by the microorganisms with ferrous ions as the substrate was conducted into the leaching reactor to dissolve electrode materials.
The efficiency of a batch treatment of batteries was examined. The results showed that the complete dissolution of two AA-sized
Ni-Cd batteries with 0.6 L/d acid supernatant took about 30, 20, and 35 days for Ni, Cd, and Co, respectively. But the dissolution
ability of the three metals was different. Cd and Co can be leached mostly for pH below 4.0 while the complete dissolution
of Ni can be achieved for pH below 2.5. Meanwhile, a strain (named Thiooxidans. WL) accounting for the reduction of pH in the acidified sludge was isolated and sequenced. It was identified to be 100% similar
to Acidithiobacillus ferrooxidans strain Tf-49 based on 16S rDNA sequence analysis. The relevant phylogenetic tree constructed indicates that the strain should
be classified into genus Acidithiobacillus ferrooxidans. |
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Keywords: | biohydrometallurgy spent Ni-Cd batteries 16S rDNA sequence analysis Acidithiobacillus ferrooxidans |
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