Pretreatments Behavior of Municipal Solid Waste Incineration Fly Ash Using Different Alkaline Reagents

Municipal Solid Waste Incineration Fly Ash (MSWIFA) contains and organic toxic pollutants, which cause secondary pollution to the environment such as water and soil, and pose a threat to human health. Its suitable treatment of the MSWIFA as a secondary use of the solid waste resources is a hot spot of the current research. This paper aims to investigate the behavior of alkaline reagent pretreatment of MSWIFA, different kinds of alkaline reagents were used to pre-treat MSWIFA. The particle size, microstructure change, element composition, phase change and leaching toxicity of heavy metal ions were studied the MSWIFA, respectively. The following conclusions were mainly obtained: after pre-treatment of MSWIFA with alkaline reagents, the average particle size tends to decrease (down to 13.98 μm). The increasing of intergranular repulsion leads to a uniformly dispersed and dense microscopic morphology of MSWIFA. The increasing of SiO₂ and Al₂O₃ content resulted in a decreasing in MSWIFA alkalinity (minimum value of 9.24) and an increasing in both its volcanic ash activity. The leaching concentration of the four heavy metal ions, namely Pb, Zn, Cu and Sr were decreased. Overall, alkaline solution pretreatment of MSWIFA was more effective, while 0.35 mol/L Na₂CO₃ had the best effect. The lowest leaching concentrations of Pb, Zn, Cu, and Sr were 3.97 mg/L, 1.58 mg/L, 4.13 mg/L, and 4.6 mg/L respectively. Alkaline reagent pretreatment of MSWIFA mainly includes: alkaline environment effect, chemical reaction effect and particle size effect. This study can provide theoretical basis for MSWIFA pretreatment and effective secondary application.