Bioremediation by phosphate-solubilizing bacteria (PSB) has attracted extensive attentions
due to its economical and eco-friendly properties for lead (Pb) passivation in soil.
Herein, bone char (BC) supported biochemical composite (CFB1-P) carrying advantages
of BC, PSB, iron sulfide (FeS) and carboxymethyl cellulose (CMC) was designed and
applied to Pb passivation. The composite at a mass ratio of BC:CMC:FeS = 1:1:1 possessed
high passivation efficiency (65.47%), and has been demonstrated to offer appropriate
habitat environment for PSB to defend against Pb(II) toxicity, thus enhancing the
phosphate-solubilizing amount of PSB to 140.72 mg/L for passivating Pb(II). Batch
experiments showed that the CFB1-P possessed excellent adsorption properties with
maximal monolayer Pb(II) uptake of 452.99 mg/g during an extensive pH range of 2.0-6.0.
Furthermore, by applying CFB1-P dosage of 3% into Pb-contaminated soil, the labile
Pb fractions were reduced from 29.05% to 6.47% after simulated remediation of 10 days,
and converted into steady fractions. The CFB1-P was demonstrated to achieve high Pb(II)
passivation through combined functions of chemical precipitation, complexation, electrostatic
attraction and biomineralization, accompanied by the formation of more stable crystal
structures, for instance, Pb5(PO4)3OH, Pb3(PO4)2 and PbS. These results suggested
CFB1-P as a potential alternative for efficient remediation of Pb-contaminated soil.