Packed Bed Reactor Model for De-mercurization of Simulated Mercury-Laden Wastewater

Microbial reduction of soluble bivalent mercury to its less toxic elemental metallic form was performed using mercury-resistant Bacillus cereus (JUBT1) isolated from the sludge of chloralkali industries. A lab-scale 1 m long and 0.05 m diameter packed bed biofilm reactor was designed to remove mercuric ions (Hg) using isolated bacterial consortium. The bioreactor was continuously fed with sterile simulated wastewater containing HgCl2 to reduce bivalent mercury to its elemental form by growing bacterial biofilm on porous packing material of the reactor. The performance efficiency of the reactor was studied varying different chemical and hydrodynamic parameters such as inlet concentration of mercury and inlet flow rate of simulated mercury-laden water, among others. The reactor was followed by an activated carbon-based adsorber to remove residual mercury in the reactor effluent. A maximum of 97-98% removal efficiency was obtained with respect to the concentration of Hg in the inlet water. A deterministic mathematical model was developed to explain the performance of the packed bed reactor. _____________________________________________________________________________________________________________