Experimental study of high concentration heavy metals co-contaminated soils stabilized with new product-based binders
Synthetic precipitation leaching procedure and pH testing of five types of industrial waste,waste biomass,and mineral material treated soils were carried out on artificially prepared high-concentration heavy metals co-contaminated soil.It was found that different binder raw materials have significant selectivity for the immobilization of heavy metals including Pb,Zn,Cd,and As.Besides,the production cost,environmental friendliness,and energy consumption of the binder raw materials were taken into account to screen the preferred raw materials that could offer better overall performance.Two new product-based binders,named B1 and B2,were then prepared by compounding the selected binder raw materials.The curing effect and long-term stability of the new binder,as well as the pH,unconfined compressive strength,and permeability coefficient of the cured soil were tested using a really high concentration of contaminated soil as the target.The results show that B1 and B2 have a satisfactory stabilization effect on four heavy metals,and the stabilization rates of heavy metals are higher than 80％at all dosage levels,which increases with increasing dosage levels.B1 was better than B2 for the stabilization of Pb,Zn,and Cd,while B2 was better than B1 for the stabilization of As.The stabilization of Pb,Zn,Cd,and As in the soil mainly occurred within 28 days,and the leached heavy metals concentrations from the treated soils reduced with curing time.In addition,both the two new binders treated soils have excellent long-term stability.Both B1 and B2 led to a significant increase in the pH of the contaminated soil.Compared with B1,B2 can significantly increase the strength of the co-contaminated soil and reduce the permeability of the solidified body,resulting in a better overall remediation performance.
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