Biosorption of Aqueous Pb(II) by a Metabolically Inactive Battery Recycling Plant Consortium: the Role of Paraclostridium Bifermentans Microbial Strain

Abstract

A microbial consortium which was obtained from lead contaminated soil at a battery recycling plant in South Africa has been demonstrated to remove 90 % of Pb(II) from an 80 mg/L solution over a period of 7 days. The consortium was effective at precipitating Pb(II) from solution and was shown to remove approximately 50 % of Pb(II) at conditions of 80 and 500 ppm within the first 3 hours. Study shows that the identities of the precipitates vary for each microbial strain, as PbS and ???? 0 were the main species precipitated by P. bifermentans and PbO with either PbCl or ???? 3 ???? 4 2 precipitated by K. pneumoniae. FTIR spectroscopy supported the chemisorption of Pb(II) onto functional groups as being responsible for this removal confirming biosorption being responsible for the initial phase of Pb(II) removal which acts as a vehicle for concentrating Pb(II) on the surface of the bacteria before bioprecipitation takes place. Functional groups identified in both the consortia and P. bifermentans are alkyl halides, phenols, aromatic, and alkene. Metabolically inactive consortium and P. bifermentans removed 54.44 mg/g and 27.39 mg/g of Pb(II) in 3 h respectively. The adsorption kinetics shows that two-phase pseudo-first-order kinetics represents the data better than pseudo-first-order and pseudo-second-order kinetics. These results provide further insights into the Pb(II) removal mechanisms required for eventual scaling of these processes.