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

Abstract

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 including humans. Due to the chemical nature of these metals, bioremediation by conventional methods is more difficult to achieve compared to other metals. In this study, we used three biosorbents (oak powder, gall nut, and bacterial exopolymer) for the 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. The biorefining process was carried out in glass columns, made of Pyrex, with dimensions 20 × 7/2 cm² with a 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 investigated biosorbents could be use as an integrated biosorption system for the refinement of mixed wastes.

Keywords:

• bacterial exopolymer
• oak
• gall
• biosorbent