Flowing-water remediation simulation experiments of lead-contaminated soil using UCB technology.

The flowing-water remediation of contaminated soil was investigated. Urease combined with biochar (UCB) technology was used to handle the Pb-contaminated sand column. The results showed that with the continuous increase of pore volume, the concentration of Pb in the leachate undergoes three stages: slow growth, rapid growth, and steady state. With increasing seepage velocity, the concentration of Pb in leachate increased slightly. The residual amount of each section of the sand column gradually decreased with increasing migration distance. The comparative results indicated that the UCB technology had a good solidification effect on Pb. This was due to urease-induced CaCO precipitation, cementation, and adsorption of Pb. Biochar provided more nucleation sites for urease, and some Pb was adsorbed on its surface or diffused into the pores of biochar, or ions exchanged with functional groups on the surface of biochar, which effectively stabilized the free Pb.