Considering that heavy metal pollution problem is widespread in the soil of South China, bioleaching process and bioleaching combined with Fenton-like reaction were used to study the removal performance of Cu, Zn, Cd and Pb in the contaminated soil around the lead-zinc mine in ShaoGuan City, Guangdong Province, China. Sequential chemical extraction was applied to analyze the effects of different treatments on the fracion distributions of Cu, Zn, Cd and Pb. The results showed that 66.5% of copper,55.1% of zinc, 72.8% of cadmium and 35.6% of lead could be removed after 12-day bioleaching process, among which, the inorganic bound-fracion had the best dissolution efficiency. The rest of the heavy metals in solid phase mainly existed in the form of stabilized residual fraction. With an optimal H2O2 concentration of 5 g·L-1, the removal efficiencies of Cu, Zn, Cd and Pb were 55.6%, 50.6%, 60.7% and 30.5% respectively after 2-day bioleaching combined with Fenton-like reaction, which indicated that this treatment was less effective than 12-day bioleaching, but significantly more effective than the H2SO4 leaching, 2-day bioleaching, and Fenton reaction. The bioleaching combined with Fenton-like reaction could realize the effective dissolution of stable-state heavy metals such as residual fraction, organic bound fraction and inorganic bound fraction in the soil, the contents of Cu, Zn, Cd and Pb were below the limit value of standand of 50, 200, 0.3 and 250 mg·kg-1 after the treatment, respectively. It possesses the advantage of high removal efficiency in bioleaching and rapid reaction rate in Fenton reaction, thus, it is a promising remediation treatment for heavy metal contaminated soil.
Keywords: Fenton-like reaction; bioleaching; contaminated soil; heavy metals; removal efficiency.