Feasibility of using Fe⁰ to remediate groundwater lead pollution in an abandoned tailings dam

In order to provide technical support for the remediation of heavy metal of Dajiaoling tailings dam, experiments concerning the Pb(II) removal efficiency and its influencing factors in groundwater by iron (Fe⁰) were conducted on the basis of analysis of the heavy metal content and distribution. The results show that the lead pollution in groundwater can be efficiently removed by Fe⁰ by redox reaction and floc adsorption. The optimal parameters were obtained by experimentation: the particle size of iron powder is 400 mesh, the original concentration of Pb(II) is 10 mg/L and the reaction time is 90 min. With increases in the iron powder dosage, the removal rate of Pb(II) increases. When the iron powder dosage increases by some degree, the removal rate of Pb(II) will not increase obviously. The removal rate of Pb(II) is significantly increased by an acid pretreatment and a binary metal addition. Simultaneous use of Fe⁰ and sawdust achieves better and more stable removal efficiency because of the combination effects with chemical reactions and microorganisms. The best reaction rate and removal efficiency are shown after activated carbon is added, arising from a combined effect by chemical, biological and physical actions.