Biosorption of heavy metals in automobile panel workshop effluent using Bacillus safensis LAU13

Abstract

Heavy metals are natural constituents of the environment, but improper application for human activities has altered their geochemical compositions and biochemical balance. There is a need to remediate heavy metals released into natural resources through anthropogenic activities. This paper centers on remediation by biosorption as an effective technique for reduction in the concentration of Mn, Co, Cu, Fe, Zn, Hg, Se, Cr, Pb and Cd using Bacillus safensis LAU13.Wastewater samples were obtained from Gbade automobile panel workshop, Grammar School area, Ogbomoso, Nigeria. Initial concentrations of heavy metals in the effluent samples after digestion were determined through Atomic Absorption Spectrometery (AAS). The glucose enriched wastewater samples were autoclaved, the inoculums cultured and subjected to bio-treatment using 250, 500, 750 and1000 µL dosages of Bacillus safensis LAU 13 (Gen Bank accession number KJ461434), a Gram-positive, mesophilic, spore-forming, aerobic and chemo- heterotrophic bacterium. Optical density of inoculated samples was determined through spectrophotometer and the growth monitored for 48hrs. Residual pellets were subjected to Scanning Electron Microscopy (SEM). Results showed that 100% removal was achieved for Mn2+ and Co3+. Chromium was reduced to a very minimal concentration, Zn2+, Cu3+, Pb4+and Se4+ were above average in the irremediation. Fe2+and Cd2+were remediated below average but very low remediation of Hg2+ with less than one percent removal. Optical density increased significantly showing rapid growth of micro-organism irrespective of glucose supplement, and 250 µL inoculum dosage has the optimum performance. SEM micrographs indicate certain accumulated aggregates taken as remediated heavy metals. The study confirmed efficiency of biosorption technique as an alternative to the conventional treatment methods of huge cost, and high precipitates and slurry. B. safensis LAU13 is therefore recommended as a bio-remediating agent in treating automobile workshop effluents with high amount of manganese, cobalt, chromium, zinc, copper, lead and selenium.