Characteristics of Bottom Ash from Municipal Solid Waste Incineration

Waste-to-energy technologies are widely used for municipal solid waste management. Municipal solid waste incineration has reduced waste volume by 90%. The combustion process results in two types of waste: fly ash (FA) and bottom ash (BA). This study focuses on the chemical and environmental properties of municipal solid waste incineration (MSWI) bottom ash. The chemical composition and leaching properties of BA from Lithuania's waste-to-energy plant, located in Klaipeda, was determined. Results show that chemical BA composition is almost stable in time and that major elements are silicon dioxide (57 +/- 2%), calcium oxide 16 +/- 2.5% and iron oxide 8 +/- 3.2%. The concentration of various heavy metals in BA is < 1%. Leaching tests showed that from BA leached large quantities of soluble salts (sulphates 2,816-10,012 mg kg(-1) and chlorides 1,869-3,046 mg kg(-1)) and certain heavy metals (Mo 0.5-1.8 mg kg(-1), Pb 0.1-2.5 mg kg(-1)). MSWI bottom ash does not meet the requirements for inert waste (2003/33/EC) but meets those for waste removal in non-hazardous waste landfills. The changing concentration of environmentally hazardous heavy metals indicates that the need for continuous BA eluate test is important.