Fixating lead in coal gangue with phosphate using phosphate-dissolving bacteria: Phosphorus dissolving characteristics of bacteria and adsorption mechanism of extracellular polymer

Controlling and preventing lead pollution is currently the focus of environmental remediation. Coal gangue contains large quantities of lead, and its environmental impact cannot be ignored. This study investigated the tolerance of Stenotrophomonas maltophilia (YZ-1 train) to lead ion and its fixation effect on lead in coal gangue. The fixation mechanism of lead ions by using the YZ-1 train was studied with CaHPO4 and Ca3(PO4)2. The tolerance mechanism and fixation characteristics of the three bacterial extracellular polymers and cell components to lead were analyzed. The results show that the YZ-1 train had a strong resistance to lead ions. The amount of lead released from coal gangue can be reduced by up to 91.1% upon treatment with the YZ-1 train, which can dissolve phosphate minerals to form stable hydroxyapatite (Pb5(PO4)3(OH)) and pyromorphite (Pb5(PO4)3Cl) with lead ions. Tryptophan and tyrosine from cellular components and extracellular polymers with loosely and tightly bound proteins are the main participants in the fixation of lead ions. The by-products of soluble microbes affect the fixation of lead ions in soluble extracellular polymers. The carboxylic acids and carboxylates secreted by bacteria are involved in the adsorption and fixation of lead ions. [Display omitted] •Solubilization of P and fixation of Pb2+ by YZ-1 strain in coal gangue was studied.•YZ-1 Strain could fix Pb2+ by dissolving phosphate minerals to form Pb-phosphate.•Barrier for YZ-1 strain to tolerate Pb2+ was the adsorption and inhibition of S-EPS.•The realization of soil utilization of coal gangue can be obtained with YZ-1 strain.