Studies on mercury bioremediation by alginate immobilized mercury tolerant Bacillus cereus cells

The current study was aimed at using immobilized mercury bioaccumulating Bacillus cereus cells for the remediation of mercury from synthetic effluent. The remediation process was attempted under different experimental conditions. The different adsorption kinetics, equilibria, and thermodynamics were also investigated in an attempt to develop an effective and better biosorbent for mercury remediation. The maximum biosorption capacity of the immobilized cells was found to be 104.1 mg g−1. The mean free energy value, as evaluated using the Dubinin–Radushkevich (D–R) model, was 15.8 kJ mol−1. This indicates that the mercury remediation process under investigation was chemically more favorable than the physical adsorption process. The remediation process was seen to follow pseudo-second-order kinetics. The apparent free energy change showed that the biosorption process of mercury was thermodynamically feasible and spontaneous in nature. The feasibility of using immobilized cells in a continuous column for effective mercury remediation was also attempted. The breakthrough point was obtained after 11 h of continuous flow. Thus, according to the study, the alginate immobilized B. cereus cells constitute a prospective mercury remediation system, which can effectively be used in mercury contaminated aqueous environment.

► An efficient mercury remediation by alginate immobilized Bacillus sp. system.
► Mercury removal capacity of immobilized Bacillus sp. cells 104.1 mg g−1.
► Thermodynamically favorable and feasible remediation process.