Characteristics and Solidification/Stabilization Experiments of Fly Ashes from Municipal Solid Waste Incineration Plants in a Southern City

Municipal solid wastes in a southern city were disposed by incineration.Seven plants were constructed,which generate101.62 tons of fly ash per day.In this paper,the chemical compositions and leaching heavy metals of fly ashes from the incineration plants were analyzed.It showed that it mainly consisted of CaO,SiO2,MgO,Al2O3,Fe2O3,Na2O,SO3 and Cl.There was at least one of the heavy metals in the fly ashes from every plant over the discharge standard,belonging to hazardous wastes.Considering the urgent need for fly ash disposal,stabilization technology of fly ash was investigated.Addition of 10% cement into fly ashes can reduce the leaching concentrations of heavy metals(Cd,Pb,and Zn) under their regulatory limits for hazardous wastes identification and safe landfill.At the same time,feasibility of exemption of fly ash from hazardous wastes was analyzed on the basis of risk assessment of human health.Finally,the disposals of fly ash in this city at present and in the long term were discussed.