Efficient lead immobilization by bio-beads containing Pseudomonas rhodesiae and bone char

Mineralization of lead ions (Pb2+) to pyromorphite using phosphorus-containing materials is an effective way to remediate lead (Pb) contamination. Bone char is rich in phosphorus, but its immobilization of Pb2+ is limited by poor phosphate release. To utilize the phosphorus in bone char and provide a suitable growth environment for phosphate-solubilizing bacteria, bone char and Pseudomonas rhodesiae HP-7 were encapsulated into bio-beads, and the immobilization performance and mechanism of Pb in solution and soil by bio-beads were investigated. The results showed that 137 mg/g of phosphorus was released from bone char in the presence of the HP-7 strain. Pb2+ removal efficiency reached 100 % with an initial Pb2+ concentration of 1 mM, bone char content of 6 g/L, and bio-bead dosage of 1 %. Most Pb2+ was immobilized on the surface of the bio-beads as Pb5(PO4)3Cl. The soil remediation experiments showed a 34 % reduction in the acid-soluble fraction of Pb. The bio-beads showed good stability in long-term (30 d) soil remediation. The present study shows that bone char can be turned into an efficient Pb immobilization material in the presence of phosphate-solubilizing bacteria. Thus, bio-beads are expected to be used in the remediation of Pb-contaminated environments.

Automated summary

Mineralization of lead ions (Pb2+) to pyromorphite using phosphorus-containing materials is an effective way to remediate lead (Pb) contamination. In this study, bone char and Pseudomonas rhodesiae HP-7 were encapsulated into bio-beads to investigate their immobilization performance and mechanism of Pb in solution and soil. The results showed that bone char could be turned into an efficient Pb immobilization material in the presence of phosphate-solubilizing bacteria, and the bio-beads exhibited good stability in long-term soil remediation.