Bioremediation of toxic metals mercury and cesium using three types of biosorbent: bacterial exopolymer, gall nut and oak fruit particles.

Cesium and mercury are two mono-valent elements which can be found in toxic industrial, medical and nuclear wastes. Their presence in the environment has deleterious effects on the ecosystem, living organisms among which humans. Due to the chemical nature of these metals, bioremediation by conventional methods is more difficult to achieve in comparison to other metals. In this study, we used three biosorbents (Oak powder, Gall nut and Bacterial exopolymer) for bioremediation of Hg and Cs. Bio-polymer was produced in the GMS mineral broth. Synthetic wastes of Hg (NO3) 2 and isotope Cs-133 as the single metal solutions were used. Biorefining process was carried out in glass columns, made of Pyrex, with dimensions 20 × 7/2 cm with V-shaped bottom. The samples were analyzed using atomic absorption. The experimental results showed that eliminated metal percent by Oak powder, Gall nut and Bacterial exopolymer were respectively of 94.8, 96 and 13.8% for Hg and 7.8, 4.4 and 69.4% for Cs. The tests revealed that Ca++, when used as flocculant, played a key role in both biosorption and bio-precipitation rates. Consequently, it was concluded that the biosorbents investigated could be use as integrated biosorption system for refinement of mixed wastes.