Microbacterium oxydans and Microbacterium liquefaciens: A biological alternative for the treatment of Ni-V-containing wastes

The present study evaluated 15 isolates obtained of environmental samples capable of tolerating high Ni and V concentrations. Those coded as MNSH2-PHGII-1, MNSH2-PHGII-2 and MV-PHGII-2 showed a minimum inhibitory concentration higher than 200 ppm for Ni and V and showed removal percentages corresponding to 84, 75 and 26% for Ni and 60, 55 and 20.3% for V, respectively, in liquid medium. When spent catalyst was added at 16% (w/v) pulp density, the highest Ni and V removal corresponded to MNSH2-PHGII-1 and MNSH2-PHGII-2, which were identified as Microbacterium oxydans and Microbacterium liquefaciens respectively, Microbacterium oxydans was able to remove Ni at the extent of 45.4% and V at 30.4% while Microbacterium liquefaciens removed Ni at 51% and V at 41.4% from the spent catalyst. The isolate MV-PHGII-2 identified also as Microbacterium oxydans showed the lowest removal for Ni and V corresponding to 16% and 9.5%, respectively. This is the first report where strains of Microbacterium were tested for their abilities to remove Ni and V from spent catalyst, suggesting its potential use in the treatment of this solid industrial waste.