METHOD OF WASTE TREATMENT

PROBLEM TO BE SOLVED: To prevent a harmful heavy metal in a waste from being re-eluted to stabilize the harmful heavy metal by adding water glass and water to the waste containing harmful metal to mix the water glass and water into the waste. SOLUTION: A waste containing harmful heavy metals such as lead, cadmium, particularly harmful heavy metals contained in highly alkaline fly ash discharged from a refuse incineration plant, is treated. There are a method in which water glass is directly put into fly ash and water is fed to knead the ash and a method in which water is added to fly ash and the ash is kneaded to provide an emulsion and water glass is added to the emulsion to knead it. In this case, 10-30 pts.wt. of water or water glass is added to 100 pts.wt. of waste, preferably 10-20 pts.wt. of water or water glass is added. Lead ion is in dissolved state as plumbate under highly alkaline conditions. However, if the lead ion comes into contact with water glass, it is precipitated as insoluble lead silicate. Thus, harmful metals, particularly lead in fly ash can be stabilized at low cost, without consuming large amounts of materials.