Lead bioremoval by Bacillus spp. Isolated from industrial wastewater

Abstract

Four samples were collected from the wastewater of State Battery Manufacturing Company (SBMC); Babylon 2 factory in AL-Waziriya district, as triplicates. Physical and chemical measurements were carried out such as temperature, pH, Lead concentrations and their ranges were: (19.5-34.5) °C, (6.1-6.4) and (4.5-6.5) mg/L, respectively. Six dominant Bacillus spp. isolates were isolated from these samples; namely, Bacillus subtilis N1, Bacillus subtilis N2, Bacillus subtilis N3, Bacillus cereus N4, Bacillus cereus N5 , Bacillus cereus N6. These isolates were capable of removing Lead from aqueous solutions in a capacity reached 27.6 ± 1.4, 10.1 ± 1.7, 74.5 ± 0.7, 8.93 ± 2.8, 8.1 ± 3.5, 1.6± 0.7 mg/L, respectively. Whereas cell walls, extracted from the same isolates, were able to remove Pb with high efficiency reached 77.7 ± 0.3, 18.6 ± 1.2, 9.5 ± 0.7, 42.4 ± 6.3, 9.9 ± 0.9, 6.7 ± 2.1 mg/L, respectively. This study showed that there is high variation (P<0.05) in the ability of the isolated bacteria for lead biosorption. However, Bacillus subtilis N3 were the most efficient (P<0.05) in uptaking the lead from its aqueous solutions in average of (74.5 ± 0.7) mg/L compared to other bacterial species. FTIR spectrum illustrated that hydroxyl groups, carboxyl, amide, and carbonyl are the major sites for Pb binding. Cell walls of B. subtilis were able to remove almost all Pb ions from the wastewater sample (4.5 mg/L) taken from the wastewater treatment unit in the State Battery Manufacturing Company.