Comparative studies to remove cobalt ions from hazardous waste solutions by immobilized microbial species using several techniques: beads and thin film.

The study was conducted to use different microbial species isolated from low-level radioactive wastewaters (up to 2 mSv) for removing non-radioactive (Co(II)) and radioactive cobalt (Cobalt-60) from waste solutions using different immobilization techniques; beads and thin film. Simple and innovate technique was used to prepare calcium alginate thin film. The isolated bacterial species investigated were Bacillus haynesii and Bacillus aerius while fungal species were; Aspergillus foetidus, Aspergillus parasiticus, and Penicillium oxalicum. The bacterial species were immobilized in wet form, while the fungal species were immobilized in wet and dry forms using sodium alginate gel. Screening of bacterial and fungal species in free and immobilized shapes for Co(II) and Cobalt-60 removal percent and capacity was studied. Moreover, the efficient immobilized weight could be used in the different immobilization shapes was investigated. Batch experiments were used to determine the optimum environmental conditions for cobalt removal by the immobilized beads or thin film. Scanning electron microscopy was done to observe the surface changes. However, the energy-dispersive X-ray analysis results indicated the accumulation of cobalt ions on the surface. The immobilized dry P. oxalicum beads showed higher Cobalt-60 removal percent about 79.3% as compared to all other immobilized bacteria and fungi biomasses. The statistical analysis using Statistical Package of Social Science (SPSS) indicated that the studied bacterial species had significant high means with (p-value < 0.05) for the removal efficiency either free or immobilized than studied fungal species. Also, there was a significant high means for immobilization in thin film shape than immobilization in beads for removal of Co(II) in both bacteria and fungi. In contrast, the immobilized beads had a significant high mean for Cobalt-60 removal in both bacteria and fungi. [ABSTRACT FROM AUTHOR]