Investigation of the leaching behavior of lead in stabilized/solidified waste using a two-year semi-dynamic leaching...

Long-term leaching behavior of contaminant from stabilization/solidification (S/S) treated waste stays unclear. For the purpose of studying long-term leaching behavior and leaching mechanism of lead from cement stabilized soil under different pH environment, semi-dynamic leaching test was extended to two years to investigate leaching behaviors of S/S treated lead contaminated soil. Effectiveness of S/S treatment in different scenarios was evaluated by leachability index (LX) and effective diffusion coefficient (D_e). In addition, the long-term leaching mechanism was investigated at different leaching periods. Results showed that no significant difference was observed among the values of the cumulative release of Pb, D_e and LX in weakly alkaline and weakly acidic environment (pH value varied from 5.00 to 10.00), and all the controlling leaching mechanisms of the samples immersed in weakly alkaline and weakly acidic environments turned out to be diffusion. Strong acid environment would significantly affect the leaching behavior and leaching mechanism of lead from S/S monolith. The two-year variation of D_e appeared to be time dependent, and D_e values increased after the 210^th day in weakly alkaline and weakly acidic environment.