Enhanced elution of chloride ions from incinerator bottom ash

Abstract

Recycling of the incinerator bottom ash, which is discharged from solid waste treatment plants, is important since the landfilling capacity is limited, and if it is left untreated, it would generate a great environmental burden. Besides, the incinerator bottom ash has a similar chemical composition to that of cement and therefore it can be used as a substitute raw material in cement manufacturing. This recycling method would, in turn, reduce the consumption of natural resources, such as limestone and clay. Generally speaking, a high concentration of chloride leads to severe corrosion of steel, which can damage the reinforced concrete structure. The removal of chloride ions from the ash should, therefore, be carried out in advance to use it as a raw material for cement production. Thus, this study aims to find an effective method for eluting chloride ion from the incinerator bottom ash for recycling. One of the main findings of this work was that the residual chloride concentration in the incinerator bottom ash was reduced to 1.70 g/kg, eluting 87.78% of initial Cl concentration, when the ash was washed with an acetic acid solution (concentration: 1.5 mol/L) saturated with CO₂ micro-bubbles.

Keywords:

• Acetic acid
• chloride ions
• elution
• incinerator bottom ash
• CO₂ micro-bubbles
• particle size distribution